A PROSPECTIVE RANDOMIZED CONTROLLED STUDY TO ASSESS …

A PROSPECTIVE RANDOMIZED CONTROLLED

STUDY TO ASSESS THE EFFICIENCY OF ACTIVE

SELF LIGATING BRACKET SYSTEM Vs

CONVENTIONAL BRACKET SYSTEM.

Dissertation submitted to

THE TAMIL NADU Dr. M.G.R.MEDICAL UNIVERSITY

In partial fulfillment for the degree of

MASTER OF DENTAL SURGERY

BRANCH V

ORTHODONTICS AND DENTOFACIAL ORTHOPEDICS

APRIL-2016

ACKNOWLEDGEMENT

For days I had created a script in my head for this section. I really

could not wait to start writing this page, precisely because it marks the end of

my dissertation but, now I am at my wits end. None the less, I believe this is a

good time as any to show my deep sense of gratitude to the people who matter

the most to me.

I am forever indebted and owe my gratitude to my beloved mentor and

guide, Prof. Dr. N.R. Krishnaswamy, M.D.S, M.Ortho (RCS,Edin)

,D.N.B.(Ortho), Diplomate of Indian Board of Orthodontics, Professor and

Head of Department of Orthodontics, Ragas Dental College and Hospital,

Chennai for his immense patience, guidance and the support that he lent me

during this study. He has always been an epitome of perfection and has

encouraged me in many ways throughout the duration of the course to become

a better person and doctor. I am truly blessed to have spent time under his

tutelage.

I am highly grateful to Prof. Dr. M.K. Anand, M.D.S, for always

leading me to the correct direction and helping me to look for answers to my

never ending questions. I thank him for his unconditional support.

I would like to thank Dr. Kavitha, M.D.S (Sr. Lecturer) for her

profound interest, wise counsel and never ending willingness to render

generous help to me in giving this work a proper shape.

I would also like to sincerely acknowledge Dr. Shahul (Professor),

Dr. JayaKumar (Professor), Dr. Sriram (Professor), Dr. Shakeel (Reader),

Dr. Rekha (Reader), Dr. Shobana (Reader), Dr.Arathi (Sr.Lecturer),

Dr.Sraboni (Sr. Lecturer) and Dr. Rachel (Sr. Lecturer) for their support and

professional assistance throughout my post graduate course.

My sincere thanks to Prof. Mr. Kanakraj, Chairman &

Dr. S. Ramachandran, Principal, Ragas Dental College for providing me with

an opportunity to utilize the facilities available in this institution in order to

conduct this study.

My heartfelt thanks to my wonderful batchmates, Dr. Arpitha, Dr.Ravi

Teja, Dr. Diwakar, Dr. Mahalaxmi, Dr. Revathi, Dr. Sharanya,

Dr. Anushya, who were cheerfully available at all times to help me. Their

support and friendship helped me these past few years and I deeply appreciate

it.

I would also like to extend my gratitude to my juniors, Dr. Preethi R,

Dr. Preethi G, Dr. Evan, Dr. VeeraShankar, Dr. Rajesh, Dr. Vidhu, Dr.

Vineesha, Dr. Dhanalakshmi, Dr. Rishi, Dr. Swati, Dr. Aparna, Dr. Charles,

Dr. Harish, Dr. Sam, Dr. Gopi, Dr. Mathew for their support and cooperating

with me to conduct this study on their patients.

I would like to thank Mr. Ashok for helping me with the technical

work and Mr. Bhaskar, Sister Lakshmi, Sister Deviyani, Sister Kanaka,

Mrs. Ameena for their co-operation and help during my course of study.

I am blessed to have got this opportunity to thank my sister Ms Ahana

Ganguly for being my pillar of strength and always having my back and

protecting me from all the troubles I keep falling into. I am forever indebted to

her for being my comfort zone. Special thanks to my brother Mr. Sreyon

Chatterjee for his timely advise and help with all the technical support that I

needed.

Life is incomplete without the presence of true friends, they show you

the spark when the days turn gloomy and dull. I thank all my friends,

especially, Dr. Ashita Talwar, Dr. Megha Bhola, Dr. Anuj Kumar, Dr.

Deepak Singh, Ms. Shreyashi Das and Ms. Suparna Biswas for their

unwavering trust and whole hearted support in all my endeavors throughout

my life.

I dedicate this study to my father Dr. Syamal Ganguly, for his

unending trust and faith in my work and to my mother Prof. Dr. Urmi

Ganguly, for her constant encouragement and always standing by me. Words

cannot express my gratitude to my grandmother Mai, who always believed

that its never too late to fulfill our dreams. I am extremely blessed to have had

all these beautiful people in my life and I thank thee Almighty for it.

CONTENTS

S .No. TITLE PAGE NO.

1. INTRODUCTION 1

2. REVIEW OF LITERATURE 6

3. MATERIALS & METHODS 38

4. RESULTS 39

5. DISCUSSION 43

6. SUMMARY & CONCLUSION 60

7. BIBLIOGRAPHY 62

8. ANNEXURE -

Introduction

Introduction

1

INTRODUCTION

The systematic evolution of various dental materials has led to a

constant pursuit of technological advances in the field of orthodontics.

Appliance biocompatibility, treatment time and efficiency and patient

acceptance are the major confronting factors for the success of orthodontic

treatment.35

The first phase of fixed appliance orthodontic treatment is concerned

with tooth alignment, but the effectiveness of this process is dependent on

several variables. Clearly, the underlying tissue biology will play a major

significant role in the response of the periodontium to the applied orthodontic

force that provides the fundamental mechanism which allows tooth movement

through the alveolar bone.51

Although the biologic factors are largely beyond the control of the

orthodontist, more direct influence is possible achievable with the choice of

bracket system and arch wire.

When using pre adjusted edgewise brackets, important factors that

determine the rate of tooth alignment includes the bracket slot dimension, the

associated inter bracket span,51 and the choice of archwire.19,32,51

Frictional forces generated between bracket and arch wire also have a

significant effect on tooth movement.4 Friction is influenced by the physical

Introduction

2

characteristics of the archwire and bracket material, and the method of

attachment between arch wire and bracket slot.31,12

Conventionally ligated edgewise brackets incur increased levels of

frictional resistance via the elastomeric attachment between bracket and

archwire.6,7,26 To reduce unwanted friction, various types of self-ligating

bracket systems have been developed. Therefore, any appliance system that

can increase the rate of tooth alignment is a potential clinical advancement.

It has been more than 70 years since Dr. Jacob Stolzenberg described a

self-ligating edgewise bracket and the recent proliferation of various bracket

types represents a minority of the versions that have been patented since that

time.26

Proposed limitations of conventional ligating brackets include

higher frictional values, failure to maintain full arch wire engagement, force

decay of elastics, impeded oral hygiene and time consuming clinical

procedures.19

Self ligating brackets claim to overcome these drawbacks by providing

a more certain full arch wire engagement, reduced friction between bracket

and arch wire, with faster arch wire removal and ligation and lesser chair side

time.19 Reduced friction between arch wire and self ligating bracket

have been quoted by numerous authors compared with conventional

Introduction

3

brackets.51,19 Anchorage conservation with self ligating brackets is mainly due

to lower forces per unit area applied.32

Self ligating brackets have a mechanical built in device into the bracket

to close off the bracket slot. They offer better patient acceptance than steel

wire ligatures. The precision arm or the sliding fourth wall accurately locks

the archwire within the dimensions of the bracket slot ensuring complete

archwire engagement and controlled tooth movement.

Self ligating brackets (SLB) are broadly classified into Passive, Active

and Interactive and Self –ligating brackets. Active brackets, with the labial

fourth wall consists of a spring clip which is in contact with the arch wire.

These brackets express greater torque control. In the Active SLB system,

friction is produced as a result of the clip pressing against the archwire.19 In

passive SLB system, the slot is transformed into a tube by means of the labial

fourth wall that does not come into contact with the archwire. However, the

term “passive” is somewhat of a misnomer because it is passive only when

teeth are ideally aligned in 3 dimensions (torque, angulation, and in-out), and

an undersized wire would not touch the walls of the bracket slot.8

In Interactive bracket system, the clip is passive with the initial lower

dimensional wires and as the dimension of the arch wire increases the clip

actively engages the arch wire and express greater torque control, which is

required in the retraction and finishing stages of treatment.4

Introduction

4

Examples of active bracket is, SPEED (Strite Industries, Cambridge,

Ontario, Canada). Examples in the passive group are the Damon bracket

(Ormco.Glendora, Calif) and the SmartClip bracket (3M Unitek, Monrovia,

Calif).5 The In-Ovation “R” (GAC International, Bohemia, NY) and Time

(American Orthodontics, Sheboygan, Wis) are the SL systems which claim to

be interactive, but, as per Kusy31 all bracket systems—conventional, and SL

active and passive are interactive to some degree, meaning that the wire

probably touches some aspect of the bracket throughout treatment.

Bracket manufactures promote patient comfort as an advantage of self

ligating brackets in spite of the lack of concurrence in scientific literature;

more constant pain for conventional ligation.12

It has been also proposed that some self-ligating appliances might

increase the inter molar widths.6,7 The available evidence on the efficiency of

self-ligating brackets derives from a limited number of prospective and

randomized clinical trials; some have indicated differences in final molar

widths, and some have shown no differences between self-ligating and

conventional appliances.

Recently a concept termed as Dual activation system has been

introduced wherein, the anterior SLB are active in configuration and the

posterior brackets are passive in configuration.

Introduction

5

To the best of our knowledge, no previous in vivo studies have

compared the alignment efficiency and the arch dimensional changes with use

the of Dual activation self ligating bracket concept.

Thus, the purpose of this study was to compare the alignment

efficiency, the transverse arch dimensional changes and the torque expression

between Dual activation self ligating bracket system and Conventional bracket

system.

Review of Literature

Review of literature

6

REVIEW OF LITERATURE

Jacob Stolzenburg (1935),26 first introduced self ligating bracket

system and described the features of Russell Lock attachment which are

generally smoother for the patients as there are no steel ligatures present for

archwire engagement. The precision arm or the fourth sliding wall completely

secures the arch wire within the dimensions of the slot providing robust

ligation mechanism and controlled tooth movement.

Tweed (1943)65 in his philosophy of orthodontic treatment said that the

main goal is to preserve the anchorage, right from the start of the treatment

and to prevent the major reciprocal reaction that occurs during retraction stage.

Shivapuja (1994)52 in his comparative study on the effect of self

ligation bracket and conventional bracket ligation system found that the self

ligation system displayed a significantly lower level of frictional resistance,

less chairside time and improved infection control compared to ceramic or

metal brackets.

Tselepis M, West VC, Brockhurst P (1994)60 Compared the dynamic

frictional resistance between orthodontic bracket system and arch wires, arch

wire material, bracket material, bracket to arch wire angulation and

lubrication. The frictional force levels involved in sliding a ligated arch wire

through a bracket slot was measured with an universal testing machine. Of the

four factors investigated by him, all were found to have significant influence


7

on friction. The polycarbonate brackets showed the highest friction and the

stainless steel brackets showed the least. Friction is increased with the bracket

to arch wire angulation. Saliva lubrication reduced the friction significantly. A

range of 0.9-6.8 N frictional force levels were recorded. The actual force

values recorded were most useful for comparing the relative influence of the

factors tested for friction, rather than a quantitative assessment of friction in

vivo. The force levels observed suggest that friction maybe a significant

influence on the amount of applied force required to move a tooth in the

mouth.

Dwight H Damon (1998)10 compared the friction produced by three

types of conventional twin brackets with three self ligating brackets. When a

0.019 x 0.025 inch stainless steel wire were drawn through the bracket, a

conventional twin ligated bracket system with elastic modules produced 388 to

609 times the friction of passive self ligated brackets produced. Conventional

twins with metal ligatures had friction values more than 300 times compared

to the passive self ligating brackets. The active brackets produced 216 times

the friction of a passive self-ligating bracket.

Luca Pizzoni et al (1998)33 studied the frictional resistance

encountered in two self ligating bracket systems (Speed, Damon SL) and two

conventional brackets (Dentauram). These brackets were tested with four

wires (Stainless steel, Beta titanium-round and rectangular). The result showed

that round wires had a lower friction than rectangular wires. Beta titanium had


8

higher friction than stainless steel. The self ligating brackets had markedly

lower friction than conventional brackets at all angulations. It was concluded

that the selection of bracket design, wire material and wire cross section

significantly influences the forces acting in a continuous arch system.

Kapur et al (1998)29 conducted a study to compare the kinetic

frictional force of a new self ligating bracket (Damon SL) with that of a

conventional bracket. The results he revealed were that the self ligating

brackets had lower kinetic friction coefficient. They concluded that self

ligating brackets could offer a substantial clinical advantage to orthodontists

employing sliding mechanics.

Profit and Fields (2000)48 discussed the methods of anchorage

control. The extent to which anchorage should be reinforced depends on the

tooth movement that is desired. For significant differential tooth movement,

the ratio of periodontal ligament area in the anchorage unit to periodontal

ligament area in the tooth movement unit should be at least 2 to 1 without

friction, 4 to 1 with friction. Anything less produces something close to

reciprocal movement. A common way to improve the anchorage control is to

pit resistance of a group of teeth against the movement of a single tooth, rather

than dividing the arch into more or less equal segments. For all four extraction

cases with maximum anchorage consideration the three possible approaches

for space closure are:


9

1. One step closure with friction less appliance

2. A two step closure sliding the canine along the arch wire, then

retracting the incisors( like original Tweed technique)

3. Two step closure, tipping the anterior segment with some friction,

the uprighting the tipped teeth ( as in Begg technique)

Mc Laughin, Bennet and Trevisi (2001)36 discussed about the play of

the archwire placed in the bracket slot. When an undersized wire is placed in a

0.022” slot that is using a 0.019 x 0.025 inch wire as the final dimension wire

there will be slop or play of 10 degree between the slot and arch wire.

Harradine (2003)20 reported that currently available self ligating

brackets offer the valuable combination of low friction and secure full bracket

engagement. These developments offer the possibility of a significant

reduction in average treatment times and also in anchorage requirements,

particularly in cases requiring large tooth movements.

Srinivas (2003)53 has demonstrated that passive self-ligating

appliances use less anchorage than conventional appliances. This supports the

reduction in the use of anchorage devices experienced by users of passive self-

ligation. Use of intraoral expansion auxiliaries such as quad helixes or W-

springs because the force of the archwire is not transformed or absorbed by the

ligatures and the necessary expansion can be achieved by the force of the

archwires. Need for extractions to facilitate orthodontic mechanics because

alignment is not hindered by frictional resistance from ligatures and can


10

therefore be largely achieved with small diameter copper nickel titanium

archwires. Tooth alignment therefore places minimal stress on the

periodontium as it occurs and so the possibility of iatrogenic damage to the

periodontium is reduced. In addition, a passive edgewise self-ligation system

provides three key features:

Very low levels of static and dynamic friction

Rigid ligation due to the positive closure of the slot by the gate or slide

Control of tooth position because there is an edgewise slot of adequate

width and depth.

Miles P. G et al (2006)38 compared the effectiveness and comfort of

Damon 2 brackets and conventional twin brackets during initial alignment.

Comfort on the lips, more esthetic look, and bracket failure rates were also

recorded. The twin bracket was more uncomfortable with the initial arch wire.

However, at 10 weeks, substantially more patients reported discomfort with

the Damon 2 bracket when engaging the arch wire. Patients preferred the look

of twin bracket over the Damon 2 and more SLB debonded during the study.

He concluded that Damon 2 brackets was no better during initial alignment

than a conventional bracket.

Turnbull. N.R, David J Birne,(2007)62 in their prospective clinical

study, authors assessed the relative speed of arch wire changes in a patient,

comparing self ligating brackets with conventional elastomeric ligation

methods, and further assessed this in relation to the stage of orthodontic


11

treatment represented by different wire sizes and types. The time taken to

remove and ligate arch wires for 131 consecutive patients treated with either

self ligating or conventional brackets was prospectively assessed. The main

outcome measure was the time to remove or place elastomeric ligatures or

open/close self ligating for two matched groups of fixed appliance patients:

Damon 2 SLB and a conventional mini twin bracket. The relative effects of

various wire sizes and materials on ligation times were investigated. The study

was carried out by one operator. Authors found that ligation of an arch wire

was approximately twice as quick with self ligating brackets. Opening a

Damon slide was on average 1 second quicker per bracket than removing

elastic modules from the mini twin brackets, and closing a slide was 2 seconds

faster per bracket. This difference in ligation time became more marked for

larger wire sizes used in later treatment stages.

Pandis. N and Argy Polychronopoulou (2007)45 investigated the

duration of mandibular crowding alleviation with self ligating brackets

(Damon 2) compared with the conventional appliances (Microarch) and the

accompanying dental effects. Fifty four subjects were selected from a pool of

patients. Lateral cephalometric radiographs were used to assess the alteration

of mandibular incisor position before and after alignment. He concluded that

overall, no difference in the time required to correct mandibular crowding with

Damon 2 and conventional brackets was observed because in conventional

cases the stress exerted by the elastomeric modules and wire ligature adjacent


12

to the bracket sides, precluding free sliding of the wire into the slot walls and

adversely affecting movement rate. When the crowding and space in the arch

increases there is no difference found between the systems.

Daniel Rinchusea and Peter G Miles (2007)8 elucidated that the

ligation force is not transmitted to the tooth but is counteracted by the equal

and opposite force of the self ligating brackets against the arch wire. A module

exerting 50g force pulling the wire into the base of the slot is the load or

normal force, so it is pertinent in friction when sliding but does not place a

direct force on the tooth. The deflection of the arch wire exerts the force on the

tooth. Friction, which impedes the sliding movements is determined by

multiplying the coefficient of friction of the materials in contact by the normal

force, which is the force of ligation. Therefore, friction is directly proportional

to the force of ligation. The force applied to the tooth comes from the

deflection of the arch wire, so if the module does not deflect the arch wire,

then it is passive and no force is applied to the tooth. This normal force is

avoided by using a Damon or a Smart Clip bracket or passive ligation only

when the brackets and wire are ideally aligned. Any deflection of the arch wire

that engages the bracket due to rotation, tip or torque creates a normal force

and therefore classical friction. If this deflection is greater, eventually binding

and notching occur; these event cannot be avoided by any bracket design

whatsoever. So, a possible SLB in future could be a combination bracket with

both a spring clip and a passive slide. It could be also tied conventionally. If


13

low resistance to sliding is desired, the passive slide could be used, but, if high

resistance to sliding is appropriate, then the active spring clip could be used.

For example, the passive slide to reduce frictional resistance could be used in

the initial stages of treatment, and the spring clip can be utilized later in

treatment for three dimensional control. Therefore, this bracket system could

take advantage of an active spring clip or a passive slide at the orthodontist’s

discretion. Keeping in mind this idea, the clinician could determine the

particular needs and vary the type of control for each tooth. Another

possibility he stated was that of a hybrid system in various combinations of

conventional brackets and ligation, SL spring clip and SL passive slide

brackets that could be integrated into the patient’s treatment by using the same

slot size for all teeth. For instance, in the extraction space closure method of

Gianelly, with crimpable hooks and the anterior brackets could have been

conventional brackets and ligation or an active SL clip for 3D tooth control,

whereas, the posterior teeth could have passive SLB to reduce friction for

space closure by sliding. The conventional bracket, spring clip and

passive slide scheme could be modified for extraction and non-extraction

patients. Perhaps for certain non-extraction cases, all teeth could have brackets

with spring clip. Depending on the desired choice, SLB could be used

selectively with conventional brackets. For example, SLB could be used only

on teeth distal to extraction sites when closing the spaces by sliding or distal to

open coil springs when opening spaces.


14

Harradine (2008)19 stated that self ligating brackets do not require an

elastic or wire ligature systems, but have an in built mechanism that can be

opened and closed to secure the arch wire. Author explained the uses of self

ligating bracket and various designs of self ligating brackets. The advantages

are full arch wire engagement, reduced friction between bracket and the arch

wire, optimal oral hygiene, less chair side assistance and faster arch wire

removal and no meticulous ligation method. Most of the brackets have a metal

face to the bracket slot that is opened and closed with an instrument or using

finger tip. The difference between active and passive clips in terms of alloy of

which its made of, the friction and torque which alters the treatment

efficiency. In Ovation-R brackets the bracket width was reduced and this

narrower width was effective in terms of greater inter bracket span. The

disadvantages of the bracket system is that it is difficult to visualize the

gingival end of lower arch and make sit difficult to open. The lacebacks,

underties and elastomerics placed behind the arch wire also competes for

space with the bracket clips.

Paul Scott and Andrew T. Dibiase (2008)49 compared the efficiency

of mandibular tooth alignment and the clinical effectiveness of a self ligating

and a conventional pre adjusted edgewise orthodontic bracket system. It is a

multicenter randomized clinical trial. Sixty two subjects with mandibular

incisor irregularities of 5 to 12mm and a prescribed extraction pattern

including the mandibular first premolars were randomly allocated to treatment


15

with Damon 3 self ligating Vs Synthesis conventionally ligated brackets. Fully

ligated 0.014-inch Nickle Titanium arch wires were used first in both groups,

followed by a sequence of 0.014 x 0.025 inch and 0.018 x 0.025 inch Nickle

Titanium, and 0.019 x 0.025 inch stainless steel. Study casts were taken at the

start of treatment (T1), the first arch wire change (T2), and the placement of

the final 0.019 x 0.025 inch stainless steel arch wire (T3). Cephalometric

lateral skull and long cone periapical radiographs of the mandibular incisors

were taken at T1 and T3. Authors concluded that there is no significant

difference was noted in the initial rate of alignment for either bracket system.

Alignment was associated with an increase inter canine width, a reduction in

arch length, and proclination of the mandibular incisors for both appliances,

but the differences were not significant.

Hisham M. Badawi and Roger W. Toogood (2008)25 measured the

difference in third-order moments that can be delivered by engaging

0.019 x 0.025-in stainless steel archwires to active self-ligating brackets

(In-Ovation, GAC) and 2 passive self-ligating brackets (Damon2, Ormco and

Smart Clip, 3M Unitek). A bracket/wire assembly torsion device was

developed. This novel apparatus can apply torsion to the wire while

maintaining perfect vertical and horizontal alignment between the wire and the

bracket. A multi-axis force/torque transducer was used to measure the moment

of the couple (torque), and a digital inclinometer was used to measure the

torsion angle. Fifty maxillary right central incisor brackets from each of the


16

4 manufacturers were tested. Conclusions drawn were that the active

self-ligating brackets seemed to have better torque control, due to a direct

result of their active clip forcing the wire into the bracket slot. The amount of

arch wire bracket slop was considerably less for active self-ligating brackets

than passive self-ligating brackets. The active self-ligating brackets expressed

higher torque values than the passive self-ligating brackets at clinically usable

torsion angles (0°-35°). The passive self-ligating brackets produced lower

moments at low torsion angles and started producing higher moments at high

torsion that cannot be used clinically. The clinically applicable range of torque

activation was greater for the active self-ligating brackets than for the passive

self-ligating brackets. All the brackets showed significant variations in the

torque expressed; this seemed to be attributed to the variation in bracket slot

dimensions. Damon2 and Speed brackets were relatively more consistent than

Smart Clip and In-Ovation brackets.

Harradine (2008)19 stated that a combination of low friction and

secure full engagement is particularly useful in the alignment of very irregular

teeth and the resolution of severe rotations, where the capacity of the wire to

release from binding and slide through the brackets of the rotated and adjacent

teeth would be expected to significantly facilitate alignment. Low friction

therefore permits rapid alignment and more certain space closure, whereas the

secure bracket engagement permits full engagement with severely displaced

teeth and full control while sliding teeth along an archwire. It is this feature


17

that greatly facilitates the alignment of crowded teeth, which have to push

each other along the archwire to gain alignment.

Tae – kyung Kim, Ki-Dal Kim (2008)57 compared the frictional force

generated by various combinations of SLB types, arch wire sizes, and alloy

types and the amount of displacement during the initial leveling phase of

orthodontic treatment, by using a custom-designed typhodont system. Two

passive (Damon 2 and Damon 3), and 3 active SLBs (Speed, In-Ovation R,

Time 2), and Smart Clip were tested with 0.014-in and 0.016-in austenitic

nickel-titanium and copper-nickel-titanium arch wires. To simulate

malocclusion status, the maxillary canines were displaced vertically, and

mandibular lateral incisors horizontally from their ideal positions up to 3mm

with 1mm intervals. Two conventional brackets (Mini Diamond MD and

Clarity CL) were used as controls. Frictional forces were least in Damon and

IN-Ovation R brackets in the typodont, regardless of arch wire size and alloy

type. The A-Ni-Ti wire showed significantly lower frictional forces than Cu-

Ni-Ti wire of the same size. As the amounts of vertical displacement of the

maxillary canine and horizontal displacement of the mandibular incisors were

increased, frictional forces also increased.

David Birnie (2008)23 stated that The Damon philosophy is based on

the principle of using just enough force to initiate tooth movement-the

threshold force. The underlying principle behind the threshold force is that it

must be low enough to prevent occluding the blood vessels in the periodontal


18

membrane to allow the cells and the necessary biochemical messengers to be

transported to the site where bone resorption and apposition will occur and

thus permit tooth movement. A passive self-ligation mechanism has the lowest

frictional resistance of any ligation system. Thus the forces generated by the

archwire are transmitted directly to the teeth and supporting structures without

absorption or transformation by the ligature system.

Compared with conventional pre-adjusted edgewise appliances, it is

suggested that the use of passive self-ligation results in a significant reduction

in the use of anchorage devices because the frictional resistance generated by

ligatures is not present.

Jeffrey L. Berger (2008)2 showed the basis for the SPEED Design. In

1970, Dr. G. Herbert Hanson invented a miniaturized self-ligating bracket with

a super elastic nickel titanium spring clip to entrap the archwire. This flexible

spring clip can occupy either of two resting positions: “slot closed” to capture

the archwire, or “slot open” to release the arch-wire. The spring clip is also

capable of storing energy, which is gently released as corrective tooth

movement occurs. active spring clip. This fully pre-adjusted edgewise

appliance, was available in both 0.018” and 0.022” slot size. Benefits for the

clinician include:

Highly flexible nickel titanium spring clip provides precise 3-D

tooth control,

Minimal friction during sliding mechanics


19

Extended range of activation due to energy stored in spring

clip,

Large interbracket span,

Spring clip will not fatigue or plastically deform under normal

treatment conditions.

John R. Valant (2008)64 described a system which is interactive, that

is, they can exhibit either passive or active properties during any stage of

treatment at the discretion and direction of the clinician. There were principle

problems with a bracket system which is entirely active or passive, such as

difficulties in either achieving complete rotational corrections or maintaining

them once corrected, Inadequate torque control, Patient discomfort, Lessened

levels of hygiene due to bracket size and profile. This bracket system and its

mode of function, appeared to incorporate all of the desirable features that

were lacking in the systems previously used:

Minimal force and friction (passive) in the early stage of treatment

Torque and rotational control (active) in the middle and finishing

stages of treatment

Low profile (low in-out relationships)

An interactive mechanism has the inherent capacity to interact with

different arch wires in varying degrees and the amounts of force, friction, and

control that it can express. Furthermore, it is differentiated from an active

mechanism by virtue of the physical design and positional relationship of the


20

wire restraining and controlling element. Interactive clips are fabricated to

allow for varying degrees of contact with the archwires. As the wire

dimensions change, there is a gradual level of contact (variable amounts of

force and control) between the archwire and the clip. For example, in the Time

system, when 0.016 smaller round wires are used, the appliance is passive and

yields very low levels of friction and force. However, when larger rectangular

wires (eg, 0.017 x 0.025) are placed, the appliance becomes active in that it is

then able to control and finalize rotations and torque.

Padhraig S, Fleming, Andrew. T.DiBase (2009)41 compared the

efficiency of mandibular arch alignment in three dimensions with self ligating

bracket system (SmartClip) and a conventional pre-adjusted edgewise twin

bracket (Victory) in non-extraction patients. This was a prospective,

randomized, controlled clinical trial. Sixty-six consecutive patients satisfied

the inclusion criteria and were enrolled in the study. Pre treatment mandibular

arch irregularity were measured by using a co-ordinate measuring machine. A

0.016-in round martensitic active nickel-titanium aligning arch wire was

placed in all the subjects. Mandibular arch irregularity was re-measured after 8

weeks later and found that the bracket type had little influence on arch

efficiency. Authors concluded that efficiency of alignment in the mandibular

arch in non-extraction patients is independent of bracket type. Alignment

efficiency is largely influenced by initial irregularity.


21

Padhraig S, Fleming, Andrew. T.DiBase (2009)42 compared the

effects of two pre adjusted appliances on angular and linear changes of the

mandibular incisors, and transverse mandibular arch dimensional changes over

a minimum of 30 weeks. Sixty six consecutive patients allocated to treatment

with a SLB (Smartclip) and conventional pre adjusted edgewise brackets

(Victory). Initial study models and cephalograms were obtained within a

month of starting the study. All subjects received treatment with the following

arch wire sequence: 0.016-in round, 0.017 x 0.025-in rectangular,

0.019 x 0.025-in rectangular martensitic active nickel-titanium arch wires and

0.019 x 0.025-in stainless steel arch wires. Final records, including study

models and a lateral cephalograms, were collected after a minimum of

30 weeks after initial appliance placement. Lateral cephalograms were

assessed for treatment related changes in mandibular incisor inclination and

position. Transverse dimensional changes in intercanine, and intermolar

distances, and the amount of crowding alleviated during the study period were

assessed by comparison of pre treatment and post treatment models. There was

little difference overall in the pattern of arch alignment and leveling related to

the two PEA. However, there was a statistically greater increase in intermolar

width in the group treated with SLB, although the difference was only

0.91mm.

Padhraig S.Fleming,a Andrew T.DiBiase,b and RobertT.Lee43

tested the hypotheses that treatment with 2 fixed orthodontic appliances


22

(SmartClip andVictory;3MUnitek, Monrovia, Calif) would result in no

difference in (1)the duration of orthodontic treatment or (2) the number of

visits required. They randomly allocated Sixty-six patients into two groups

comprising of self ligating and conventional system. The duration of treatment

and the number of visits required in addition to the initial and final peer

assessment rating (PAR)scores were recorded. The number of teeth extracted

during treatment and the frequency of mechanical eruption of canines were

also noted. They found that in the Fifty-four participants who completed the

study. The duration of treatment was 3months greater in the group treated with

SmartClip. However, bracket type had no statistical influence on treatment

duration (P = 0.076), total visits required(P=0.184), or percentage PAR score

reduction(P= 0.255).they concluded the study saying that the self-ligating

bracket systems used in the trial neither improved the efficiency of fixed

appliance treatment nor resulted in fewer treatment visits.

Pandis. N and Argy Polychronopoulou (2010)46 compared the time

required to complete the alignment of crowded maxillary anterior teeth (canine

to canine) between Damon MX and In-Ovation R self ligating brackets, the

amount of crowding of the maxillary anterior dentition was assessed by using

the irregularity index. The number of days required to completely alleviate the

maxillary anterior crowding in the two groups were investigated. An analysis

of each protocol was performed. He concluded that there is no difference in

crowding alleviation was found between In-Ovation R and Damon MX.


23

Stephanie Shih-Hsuan Chen, a Geoffrey Michael Greenlee (2010)54

did a systematic review to identify and review the orthodontic literature with

regard to the efficiency, effectiveness, and stability of treatment with self

ligating brackets compared with conventional brackets. Self ligating appears to

have a significant advantage with regard to chair side time, based on several

cross- sectional studies. Analysis also showed a small, but statistically

significant difference in mandibular incisor proclination. No other differences

in treatment time and occlusal characteristics after treatment were found

between the two systems that are supported by the current evidence.

Retraction efficiency is not significantly efficient compared to conventional.

Long term studies are required with the greater sample size for better

understanding of the efficiency of self ligating brackets.

Padhraig S. Fleminga; Ama Johalb (2010)32 evaluated the clinical

differences in relation to the use of self ligating brackets in orthodontics. Six

RCTs and eleven CCT were identified from the electronic databases which

investigated the influence of bracket type on alignment efficiency, subjective

pain experience, bond failure rate, arch dimensional changes, rate of

orthodontic space closure, periodontal outcomes, and root resorption were

selected. Both authors were involved in validity assessment, and data

extraction. Meta analysis of the influence of bracket type on subjective pain

experience failed to demonstrate a significant advantage for either type of

appliance. Authors concluded that it was difficult to assess the efficiency at


24

this stage because there is insufficient high quality evidence to support the use

of self ligating brackets over conventional bracket system.

Emily Ong and Hugh McCallum (2010)11 compared the efficiency of

self ligating and conventionally ligated bracket system during the first

20weeks of extraction treatment. Fifty consecutive patients who had premolar

extractions in the maxillary and/or mandibular arch, 0.022 x 0.028-in slot

brackets, and similar arch wire sequences were studied. Forty four arches

received Damon 3MX brackets, and 40 arches received Victory Series or Mini

Diamond brackets. The models were evaluated for anterior arch alignment,

extraction spaces, and arch dimensions at pre treatment (T0), 10weeks (T1),

and 20weeks (T2). They concluded that there were no significant differences

between the self ligating and conventionally ligated groups at 20 weeks in

irregularity scores. There were no significant differences in passive extraction

space closures between the groups.

Nicholas Pandis, Argy Polychronopoulou (2010)46 conducted a study

to investigate the effect of treatment of mandibular crowding with self-ligating

and conventional brackets on dental arch variables and they selected fifty-six

patients who satisfied the inclusion criteria of non-extraction treatment in the

mandibular or maxillary arches, eruption of all mandibular teeth, no spaces

and an irregularity index greater than 2 mm in the mandibular arch, and no

adjunct treatment such as extra or intraoral appliances. The patients were


25

assigned to two groups: one group received treatment with the self-ligating

bracket and the other with a conventional edgewise appliance. Lateral

cephalometric radiographs were obtained at the beginning (T1) and end (T2)

of treatment were used to assess the alteration in mandibular incisor

inclination, and measurements of inter canine and inter molar widths were

made on dental casts to investigate changes associated with the correction.

Results showed an alignment-induced increase in the proclination of the

mandibular incisors was observed for both groups; no difference was

identified between self-ligating and conventional brackets with respect to this

parameter. Likewise, an increase in inter canine and inter molar widths was

noted for both bracket groups; the self-ligating group showed a higher

intermolar width increase than in the conventional group

PM Cattaneo, M Treccani, LHS Cevidanes, B Melsen (2011)40

evaluated the transversal tooth movements and buccal bone modeling of

maxillary lateral segments achieved with active or passive self-ligating bracket

systems in a randomized clinical trial. Sixty-four patients, with Class I, II, and

mild Class III malocclusions, were randomly assigned to treatment with

passive (Damon 3 MX) or active (In-Ovation R) SLBs. Impressions and cone-

beam CT-scans were taken before (T0) and after treatment (T1). Displacement

of maxillary canines, premolars and molars, and buccal alveolar bone

modeling were blindly assessed. Twenty-one patients in the Damon and 20 in

the In-Ovation group completed treatment according to the prescribed

protocol. Transversal expansion of the upper arch was achieved by buccal


26

tipping in all but one patient in each group. There were no statistical

significant difference in inter-premolar bucco-lingual inclination between the

two groups from T0 to T1. The bone area buccal to the 2nd premolar

decreased on average of 20% in the Damon and 14% in the In-Ovation group.

Only few patients exhibited widening of the alveolar process. They concluded

saying that the anticipated translation and buccal bone modeling using active

or passive SLBs could not be confirmed in the majority of the cases.

Individual pre-treatment factors, like initial teeth inclination and occlusion,

seemed to be important in determining the final outcome of the individual

treatment, and CBCT-technology combined with digital casts was important to

analyze 3D treatment outcomes both at dental and bone level in large study

groups.

Andrew T. DiBiase, Inas H. Nasr (2011)9 conducted a prospective

randomized clinical trial comparing the effect of bracket type on the duration

of orthodontic treatment and the occlusal outcome as measured by the peer

assessment rating (PAR) where sixty-two subjects with a mean pre treatment

PAR score of 39.40, along with mandibular irregularity from 5 to 12 mm, and

subjects who were prescribed extractions including mandibular first premolars

were randomly allocated to treatment with either the Damon3 self-ligated or

the Synthesis conventional ligated pre adjusted bracket systems (both, Ormco,

Glendora, Calif). An identical archwire sequence was used in both groups

excluding the finishing archwires: 0.014-in, 0.014 x 0.025-in, and


27

0.018 x 0.025 in copper-nickel-titanium aligning archwires, followed by 0.019

x 0.025-in stainless steel working archwires. Data collected at the start of

treatment and after appliance removal included dental study casts, total

duration of treatment, number of visits, number of emergency visits and

breakages during treatment, and number of failed appointments. Accounting

for pretreatment and in-treatment covariates, bracket type had no effect on the

overall treatment duration, number of visits, or overall percentage of reduction

in PAR scores. The time spent in space closure had an effect on treatment

duration, and the pretreatment PAR score influenced only the reduction in

PAR as a result of treatment. Thus, the use of Damon3 bracket does not reduce

overall treatment time or total number of visits, or result in a better occlusal

outcome when compared with conventional ligated brackets in the treatment

of extraction patients with crowding.

Johansson and Fredrik Lundström (2012)28 conducted a prospective

and randomized study of the efficiency of orthodontic treatment with self-

ligating edgewise brackets (SL; Time2 brand, American Orthodontics) and

conventional edgewise twin brackets (CE; Gemini brand, 3M). The

participants were treated by one of three specialists in orthodontics and with

continuous instructions alternately by five orthodontic assistants according to

our normal treatment routine (ie, modified 0.0220 MBT pre adjusted edgewise

technique). The treatments were evaluated in terms of overall treatment time,

number of visits, and treatment outcome using the Index of Complexity,

Outcome and Need (ICON). The number of emergency appointments, number


28

of archwires, overjet, relative space, and extractions at treatment start were

noted. After dropouts, the analyzed material consisted of 44 patients treated

with SL and 46 patients treated with conventional. It was found that were no

statistically significant differences between the SL and CE groups in terms of

mean treatment time in months (20.4 Vs 18.2), mean number of visits

(15.5 Vs 14.1), mean ICON scores after treatment (13.2 Vs 11.9), or mean

ICON improvement grade (7.9 Vs 9.1) thereby, they concluded saying that

orthodontic treatment with SL brackets does not reduce treatment time or

number of appointments and does not affect post treatment ICON scores or

ICON improvement grade compared with CE brackets.

Prettymana et al (2012)47 evaluated the significant clinical differences

between self-ligating brackets and conventional brackets during orthodontic

treatment, as perceived by orthodontists. They conducted a survey to assess

how SLB was compared to CB in terms of orthodontists’ perceptions

(n= 430).

Results showed that Self Ligating Brackets were preferred during the

initial stage of treatment based on the shorter adjustment appointments and

faster initial treatment progress they provided (P =0.001). On the other hand,

practitioners preferred CB during the finishing and detailing stages of

treatment (P =0.001). CB were also preferred over SLB because they were

cheaper.

Nigel Harradine (2013)22 summarized the advantages of self ligation

system thus, contribuiting to increased efficiency of the brackets. The


29

advantages included full secured ligation without the problems of force decay

in elastomeric modules, faster ligation and arch wire removal which saves

upto 9 minutes per visit compared to the conventional, rapidity of treatment

due to lower resistance to sliding inside the bracket slot.

Padhraig S. Fleminga and Kevin O’Brien (2013)14 contradicted the

advantages put forth by other authors saying that there was no significant time

difference for slide closure and replacement of ligatures and it is controversial

to say that self ligating brackets helps in faster alignment or in rapid space

closure.

Pandis and Padhraig S. Fleming (2014)15 did a network meta

analysis on the Initial orthodontic alignment effectiveness with self-ligating

and conventional appliances and the NMA results indicated that the

conventional appliances perform better in terms of alignment efficiency

compared with all other systems, with greater mean improvements of 0.03,

0.08, and 0.17 mm per month compared with In-Ovation-R, Damon, and

Smart-Clip, respectively.

Goldie Songra,a Matthew Clover(2014)17 compared the time to

initial alignment and extraction space closure using conventional brackets and

active and passive self-ligating brackets. They selected one hundred

adolescent patients 11 to 18 years of age undergoing maxillary and mandibular

fixed appliance therapy after the extraction of 4 premolars who were

randomized with stratification of 2 age ranges (11-14 and 15-18 years) and

3 maxillo mandibular plane angles (high, medium, and low) with an allocation


30

ratio of 1:2:2. Allocation was to 1 of 3 treatment groups: conventional

brackets, active self-ligating, or passive self ligating brackets. All subjects

were treated with the same arch wire sequence and space-closing mechanics.

Labial-segment alignment and space closure were measured on study models

taken every 12 weeks throughout treatment. Results demonstrated a significant

effect of bracket type on the time to initial alignment (P = 0.001), which was

shorter with the conventional brackets than either of the self-ligating brackets.

There was no statistically significant difference between any of the 3 bracket

types with respect to space closure. Space-closure times were shorter in the

mandible, except for the Damon 3MX bracket (Ormco, Orange, Calif), where

active and total space-closure times were shorter in the maxilla. The following

conclusions that were drawn from this study was

1. There was no statistically significant difference in the time to initial

alignment between active and passive self-ligating brackets. The time

to alignment was significantly shorter with conventional brackets.

2. There was no significant difference in the time to passive, active, or

total space closure among all bracket types.

3. There was a statistically significant difference in the time to initial

alignment between the mandible and the maxilla, with a shorter time to

alignment in the maxilla.

4. There was a statistically significant difference in space closure with

time between the mandible and the maxilla.


31

Megha Anand,a David L. Turpin (2015)63 did a retrospective cohort

study to assess the effects and efficiency of selfligating brackets compared

with conventional brackets along with a secondary purpose was to identify the

pretreatment factors associated with the choice of self-ligating or conventional

brackets. The subjects were treated by 2 private practitioners who used both

self-ligating and conventional brackets in their practices. The self ligating

subjects were consecutively identified (treatment completed between January

2011 and April 2012), and then an age- and sex-matched control group was

chosen from the same office. The outcome measures were changes in arch

dimensions, changes in mandibular incisor inclinations, final peer assessment

rating (PAR) scores, percentages of PAR reduction, overall treatment times,

total number of visits, and number of emergency visits. The final sample

comprised 74 patients. Results found were that the practitioners had

significant differences for several treatment parameters; therefore, the data

from the 2 clinicians were analyzed separately. For clinician 1, no significant

differences were observed between the self-ligating and conventional groups,

other than increased arch length in the self-ligating group. The self-ligation

patients treated by clinician 2 demonstrated significant increases in transverse

dimensions, lower percentages of reduction in PAR scores, shorter treatment

times, fewer visits, and more wire-sliding emergencies than the conventional

bracket group. Therefore, the study suggested that the bracket system, per se,

may not have a major effect on arch dimensions, mandibular incisor

inclinations, occlusal outcomes and treatment efficiency and it is possible that


32

the variations in these parameters may depend more on patient characteristics,

such as initial crowding or military population, or on treatment choices made

by the clinician, such as arch wire sequence and form, mechanic.

Materials and Methods


33

MATERIALS AND METHODS

Sixteen consecutive patients who met the selection criteria were

included in the study conducted in the Dept. of Orthodontics, Ragas Dental

College & Hospital, Chennai.

The inclusion criteria for all sixteen patients were as follows:

1. Age criteria: 14 to 25 years old having permanent dentition of either

gender.

2. Angles Class I, Class II Division 1 and Bi-dento alveolar

malocclusion requiring all first bicuspid extraction followed by fixed

orthodontic therapy.

3. Patients with Little’s irregularity index score of ≥ 2 for dental

crowding.

4. Group A anchorage.

5. First and second molars to be banded or bonded in maxillary and

mandibular arch.

Patients with previous history of orthodontic treatment, any missing

tooth other than third molars, with cleft lip and palate or any craniofacial

deformity or temporo-mandibular dysfunction were excluded from the study.

Four patients failed to keep up with the appointments and were excluded from

the study.


34

Twelve patients were randomly divided into two groups of six each:

Group A and Group B

Group A patients were bonded with Self Ligating pre-adjusted

edgewise, Roth 0.022 slot brackets (Dual activation Empower; American

Orthodontics, Sheboygan, WI,USA) and Group B patients was bonded with

Conventional pre-adjusted edgewise Roth 0.022 slot brackets (Mini Master

series; American Orthodontics, Sheboygan, WI,USA), which were positioned

using Boon’s gauge in the upper and lower arches. The first and second molars

were banded or bonded with Roth’s prescription with weldable or bondable

buccal tube and lingual sheath were used in the first molars for placement of

transpalatal arch if required.

Arch form used in the study was the Type III Arch form (American

Orthodontics, Sheboygan, WI,USA).

Leveling and aligning was done using a specific archwire sequence:

1. 0.016” round thermal NiTi

2. 0.018” round stainless steel with reverse curve

3. 0.019 x 0.025” NiTi

All the arch wires were to be changed only after it sits passively in the

bracket slots. All subjects were reviewed after an interval of 4 weeks. Once

the level slot alignment was achieved with 0.019x0.025” NiTi wire, the


35

0.019 x 0.025” stainless steel wire was inserted when it passively fitted into

the bracket slot.

Stainless steel ligatures or elastomeric modules were used to secure

archwire into the conventional brackets. Arch wires were disengaged by

cutting the ligatures or removing the modules. For the self ligating brackets,

the clip was opened and closed using the manufacturer-recommended

instrument (Hu Friedy clip appliance wire disengagement hand instrument;

American Orthodontics, Sheboygan, WI,USA)

A set of study models and lateral cephalograms were taken at the

beginning of the treatment (T0) and at the end of Leveling and aligning stage

(T2). To calculate the alignment efficiency a set of models were taken at the

time of placement of 0.018 inch stainless steel wire (T1).

All the lateral cephalograms were traced by the same investigator.

All the study models were evaluated by using Little’s irregularity index with a

digital Verneir caliper (Insize Digital Caliper, series 1112, resolution to

0.01mm) to quantify the alignment of the six anterior teeth of maxillary and

mandibular arches.

Inter canine width and Inter second premolar width were measured

from the cusp tips of the canines and second premolars respectively on the

study models using a digital Verneir caliper. Measurements were not taken


36

from the gingival margin because the quality of the gingival impression was

inconsistent.

Intermolar widths were measured from the mesial occlusal pits of the

mandibular and maxillary first molars.

The study models were measured with digital Vernier calipers with

sharpened tips that were accurate to 0.01 mm. All model measurements were

made by the principal researcher.

Landmarks and Reference planes used:

NASION (N)- The most anterior point of the fronto-nasal suture in the median

plane

SELLA (S)- the midpoint of the hypophyseal fossa. It is a constructed point in

the median plane.

S-N PLANE- it’s the cranial line between the center of sella tursica and the

anterior point of the anterior point of the fronto-nasal suture (nasion). It

represents the anterior cranial base. (Steiner’s analysis)

POINT B- It is the most posterior point in the concavity between the chin and

the mandibular process.

MANDIBULAR PLANE- A line drawn from anatomic gonion to gnathion.


37

STATISTICAL ANALYSIS

Descriptive and analytical statistical analyses were performed with

SPSS software package (SPSS for Windows XP,version 21.0, Chicago). For

each variable measured on the study models and on the lateral cephalograms,

the Mean and Standard deviation were calculated.

Wilcoxon Signed Rank Test which is a non parametric test, was done

to compare the irregularity index at T0 (before treatment), at T1 (at the time of

placement of 0.018 inch stainless steel) and at T2 (at the time of placement of

0.019 x 0.025 inch stainless steel wire) in each Self Ligating (Group A) and

Conventional (Group B) brackets.

Mann Whitney U Test (non parametric test), was done to evaluate the

alignment efficiency at T0 (before treatment), at T1 (at the time of placement

of 0.018 inch stainless steel) and at T2( at the time of placement of

0.019 x 0.025 inch stainless steel wire) between Self Ligating (Group A) and


Parametric Paired T-Test was done to evaluate the torque expression

in each Self Ligating (Group A) and Conventional (Group B) brackets at

initial and final alignment.

Paired t-Test was done to evaluate the amount of arch expansion at

Inter Canine, Inter Premolar and Inter Molar regions, for each Self Ligating

(Group A) and Conventional (Group B) brackets at T0 (before treatment), at


38

T1 (at the time of placement of 0.018 inch stainless steel) and at T2( at the

time of placement of 0.019 x 0.025 inch stainless steel wire).

Independent T Test was done to compare the amount of torque

expression at initial and final alignment between Self Ligating (Group A) and


Independent T Test was done to compare the amount of arch

expansion at Inter Canine, Inter Premolar and Inter Molar regions, for each of

the Self Ligating (Group A) and Conventional (Group B) brackets at T0

(before treatment), at T1 (at the time of placement of 0.018 inch stainless

steel) and at T2( at the time of placement of 0.019 x 0.025 inch stainless steel

wire).

CONSORT DIAGRAM-Showing the Flow Of Participants Through The Trial

Subjects fulfilling

inclusioncriteria(n=24)

Subjects who declined treatment

(n=8)

Subjects randomized (n=16)

Dual activation self ligation system (n=8) Conventional bracket system (n=8)

Incomplete follow up (n=4)

Dual activation self ligating system (n=6) Conventional bracket system (n=6)

Impressions of all subjects were taken at T0, T1&T2

Lateral Cephalograms were taken at T0 & T1

Intra oral photographs were taken at pre and post alignment

Figures

Figures

Figure1. Dual Activation Self Ligating Bracket System

Figure 2. Conventional Bracket System

Figures

CALCULATION FOR IRREGULARITY INDEX MEASURED AT T0,T1&T2

Figure 3a. Study Group Mandibular T0 Figure 3b.Control Group Mandibular

Irregularity Index Irregularity Index T0

Figure 4a. Study Group Mandibular Irregularity Figure 4b.Control Group Mandibular Irregularity

Index T1 Index T1

Figure 5a. Study Group Mandibular Figure 5b. Study Group Mandibular

Irregularity Index T2 Irregularity Index T2

SAMPLE CONTROL

Figures

MEASUREMENTS FOR TRANSVERSE DIMENSIONAL CHANGES

Figure 6. Study Group Mandibular Inter Canine Width T0

Figure 7. Study Group Mandibular Inter Second Premolar Width T1

Figure 8. Study Group Mandibular Inter Second Molar Width T2

Figures

Figure 9a.

CEPHALOMETRIC RADIOGRAPH TO MEASURE TORQUE EXPRESSION

AT T0 (STUDY GROUP)

Figures

Figure 9b.


AT T1 (STUDY GROUP)

Figures

Figure 10a.


AT T0 (CONTROL GROUP)

Figures

Figure 10b.


AT T1 (CONTROL GROUP)

Results

Results

39

RESULTS

This study comprised of 12 patients who were divided into two groups,

Group A and Group B, each having 6 patients respectively. The mean age of

the patients was 16.8 ± 4 years in both the groups.

The irregularity index of the sample between the three time frames

were evaluated. (Table Ib). Results showed that there was a statistically

significant difference in the alignment of maxillary arch from T0 to T1

(p<0.024) and T0 to T2 (p<0.020) and mandibular arch from T0 to T1

(p<0.027) and T0 to T2 (p<0.024). However, no statistically significant

difference was there for both maxillary and mandibular arches in the time

frame of T1 to T2. Therefore, the major alignment difference is seen from T0-

T1 (Table Ib).

The irregularity index of the control group were tabulated in (Table Ic)

which showed that there was a statistically significant difference in the

alignment of maxillary arch from T0 to T1 (p<0.026) and from T0 to T2

(p<0.026). In the mandibular arch, statistically significant difference is seen

between T0 to T1 (p<0.026) and from T0 to T2 (p<0.27). However, no

statistically significant difference was found in maxillary arch in the time

frame of T2 to T1. Therefore, the maximum amount of alignment was seen

from T0-T1 (Table Ic).

Results

40

The comparison of the irregularity scores between sample and control

was evaluated (Table Id). Results showed that there was a statistically

significant difference at the start of the study T0 (p<0.045) with the sample

group having a higher irregularity score than the control. However, no

statistically significant difference was found between the sample and the

control over the two time frames; it showed that the irregularity score was

higher for sample, in the time period T0-T2. Hence, the sample group showed

better alignment efficiency than the control group (Table Id).

Amount of time taken for Alignment between sample and control was

evaluated (Table IIb). Results showed that there was a statistically significant

difference in alignment time taken for maxillary and mandibular arch between

T1 to T2 (p<0.026). No satistically significant difference was found between

other time periods. In total time taken, a significant difference (p<0.016) was

found between the sample and the control with a mean difference of 3 weeks.

(Table IIb).

The amount of torque expression in the sample group between pre (T0)

and post alignment (T2) was tabulated in (Table IIIa.) There was no

statistically significant difference in lower incisor to nasion-point B in the

angular measurements (p>0.084) though there was a mean decrease of 5° in

the post alignment values (Table IIIa).

Results

41

Amount of torque expression for Control group between pre (T0) and

post alignment stage (T1) were tabulated (Table IIIb). Results showed that

there was no statistically significant difference in the torque expression for

lower incisor to point B in the angular measurements (p>0.310) though there

was a mean decrease of 2° in the post alignment values (Table IIIb).

Amount of Torque expression between the Sample and Control groups

were tabulated in table IIIc. Results showed no statistically significant

difference in the amount of torque expression for mandibular incisors in the

post alignment phase between sample and control with the p value of p>0.091

(Table IIIc).

The intercanine width of the sample and control group is evaluated

(Table IVa). Results showed no statistical significant difference in the sample

group.

The inter premolar width of the sample and control group is evaluated

(Table IVb). Results showed no statistical significant difference in the sample

group.

The inter molar width of the sample and control group were evaluated

(Table IVc). Results showed no statistically significant difference in the

sample and control group for maxillary and mandibular arches.

Results

42

The intercanine width between the sample and the control over the

three time frames was tabulated (Table IVd). Results showed that there was no

statistically significant difference in the inter canine width between TO, T1

and T2 in both maxillary and mandibular arches.

The inter Premolar width between the sample and the control over

the three time frames were tabulated in the (Table IVe). Results showed that

there was no statistically significant difference in the inter Premolar width

between TO, T1 and T2 in both maxillary and mandibular arches.

The inter Molar width between the sample and the control over the

three time frames were tabulated (Table IVf.) Results showed that there was

no statistically significant difference in the inter Molar width between TO, T1

and T2 in both maxillary and mandibular arches.

So, there was no statistically significant difference in the amount of

transverse dimensions measured in the regions of inter canine, inter premolar

and inter molar both in the maxillary and mandibular arches for both samples

and control.

Tables &Graphs

Tables and Graphs

TABLE Ia. DESCRIPTIVE STATISTICS FOR IRREGULARITY

INDEX:

Measure Statistic Group

Sample Control Total

Maxilla

(mm) - T0

N 6 6 12

Mean 4.37 3.17 3.77

Std. Dev 0.9 0.98 1.09

1st Quartile 4 2 3.5

Median 4 3.5 4

3rd

Quartile 4 4 4

Maxilla

(mm) - T1

N 6 6 12

Mean 0.5 0.58 0.54

Std. Dev 0.84 0.66 0.72

1st Quartile 0 0 0

Median 0 0.5 0

3rd

Quartile 1 1 1

Maxilla

(mm)-T2

N 6 6 12

Mean 0 0 0

Std. Dev 0 0 0

1st Quartile 0 0 0

Median 0 0 0

3rd

Quartile 0 0 0

Tables and Graphs



Mandible

(mm) - T0

N 6 6 12

Mean 4 4.75 4.37

Std. Dev 1.26 1.6 1.43

1st Quartile 4 4 4

Median 4 5 4

3rd

Quartile 4 6 5.5

Mandible

(mm) - T1

N 6 6 12

Mean 0.67 1.17 0.92

Std. Dev 0.52 0.98 0.79

1st Quartile 0 0 0

Median 1 1.5 1

3rd

Quartile 1 2 1.5

Mandible

(mm) - T2

N 6 6 12

Mean 0 0 0

Std. Dev 0 0 0

1st Quartile 0 0 0

Median 0 0 0

3rd

Quartile 0 0 0

Tables and Graphs

TABLE IB. WILCOXON SIGNED RANKS TEST TO COMPARE THE

IRREGULARITY INDEX IN EACH SAMPLE GROUP BETWEEN

T0,T1&T2.

Measures Z-Value P-Value

Maxilla (mm) - T1 - Maxilla (mm) - T0 2.264 0.024



Mandible (mm) - T1 - Mandible (mm) - T0 2.214 0.027



TABLE IC. WILCOXON SIGNED RANKS TEST TO COMPARE THE

IRREGULARITY INDEX IN EACH CONTROL GROUP BETWEEN

T0,T1 & T2








TABLE ID. COMPARISION OF IRREGULARITY INDEX BETWEEN

SAMPLE AND CONTROL USING MANN-WHITNEY TEST AT T0, T1

& T2


Maxilla (mm) - T0 2.006 0.045

Maxilla (mm) - T1 0.360 0.719

Maxilla (mm) - T2 0.000 1.000

Mandible (mm) - T0 1.169 0.242

Mandible (mm) - T1 1.024 0.306

Mandible (mm) - T2 0.000 1.000

Tables and Graphs

TABLE IIA. DESCRIPTIVE STATISTICS FOR TIME TAKEN

FOR ALIGNMENT



Time taken

T0-T1 Max

N 6 6 12

Mean 10.67 13.33 12

Std. Dev 2.07 3.27 2.95

1st Quartile 8 12 10

Median 12 14 12

3rd Quartile 12 16 14

Time taken

T1-T2 Max

N 6 6 12

Mean 8 11.33 9.67

Std. Dev 2.53 1.63 2.67

1st Quartile 8 12 8

Median 8 12 10




Time taken

T0-T1 Mand

N 6 6 12

Mean 10.67 13.33 12

Std. Dev 2.07 3.27 2.95


Median 12 14 12


Time Taken

T1-T2 Mand

N 6 6 12

Mean 8 11.33 9.67

Std. Dev 2.53 1.63 2.67

1st Quartile 8 12 8

Median 8 12 10


Total time

taken (weeks)

N 6 6 12

Mean 18.67 24.67 21.67

Std. Dev 3.27 3.01 4.33


Median 18 24 22


Tables and Graphs

TABLE IIB. TIME TAKEN FOR ALIGNMENT USING MANN-

WHITNEY TEST FOR SAMPLES AND CONTROLS


Time taken T0-T1 Max 1.563 0.118

Time taken T1-T2 Max 2.227 0.026

Time taken T0-T1 Mand 1.563 0.118

Time Taken T1-T2 Mand 2.227 0.026

Total time taken (weeks) 2.403 0.016

Tables and Graphs

RESULTS FOR TORQUE EXPRESSION

Paired samples T-Test to compare mean values of torque expression

between initial and final alignment in each Group

TABLE IIIA. GROUP: SAMPLE

Pair Measure N Mean Std. Dev t-Value P-

Value

Pair 1 IMPA-PRE 6 104.67 8.914 1.464 0.203

IMPA-POST 6 99.83 6.369

Pair 2 Lower Incisor to NB-PRE 6 36.00 6.066

2.150 0.084 Lower Incisor to NB-POST 6 32.50 4.722

Paired samples T-Test to compare mean values values of torque

expression between initial and final alginment in each Group

TABLE IIIB. GROUP: CONTROL

Pair Measure N Mean Std. Dev t-

Value

P-

Value

Pair 1 IMPA-PRE 6 111.67 3.830 1.536 0.185

IMPA-POST 6 108.33 8.641

Pair 2 Lower Incisor to NB-PRE 6 41.83 4.708

1.130 0.310 Lower Incisor to NB-

POST 6 39.83 8.353

Tables and Graphs

COMPARISON OF AMOUNT OF TORQUE EXPRESSION BETWEEN

GROUP A AND GROUP B:

TABLE IIIC. INDEPENDENT SAMPLES T-TEST TO COMPARE

MEAN VALUES OF TORQUE EXPRESSION BETWEEN SAMPLES

AND CONTROLS

Measure Group N Mean Std. Dev t-Value P-

Value

IMPA-PRE Sample 6 104.67 8.914 1.767 0.108

Control 6 111.67 3.830

IMPA-POST Sample 6 99.83 6.369 1.940 0.081

Control 6 108.33 8.641

Lower Incisor to NB-

PRE

Sample 6 36.00 6.066 1.861 0.092

Control 6 41.83 4.708

Lower Incisor to NB-

POST

Sample 6 32.50 4.722 1.872 0.091

Control 6 39.83 8.353

Tables and Graphs

RESULTS FOR TRANSVERSE DIMENSION.

TABLE IVA. PAIRED SAMPLES T-TEST TO COMPARE MEAN

VALUES OF INTER CANINE WIDTH BETWEEN T0,T1 & T2 IN

EACH GROUP: INTERCANINE WIDTH

Group Measurements N Mean Std. Dev t-Value P-Value

Sample

Pair 1 Maxilla (mm) - T0 6 36.3500 2.19049 0.908 0.405

Maxilla (mm) - T1 6 36.8833 1.02810

Pair 2 Maxilla (mm) - T0 6 36.3500 2.19049 0.776 0.473

Maxilla (mm) - T2 6 36.8233 .97336

Pair 3 Maxilla (mm) - T1 6 36.8833 1.02810 0.718 0.505

Maxilla (mm) - T2 6 36.8233 .97336

Pair 4 Mandible (mm) - T0 6 27.2683 1.46477 0.146 0.889

Mandible (mm) - T1 6 27.3600 1.13763


Mandible (mm) - T2 6 28.3283 1.41120


Mandible (mm) - T2 6 28.3283 1.41120

Control

Pair 1 Maxilla (mm) - T0 6 35.4333 2.48659 1.267 0.261

Maxilla (mm) - T1 6 36.0083 1.76436

Pair 2 Maxilla (mm) - T0 6 35.4333 2.48659 1.612 0.168

Maxilla (mm) - T2 6 36.2767 1.51191

Pair 3 Maxilla (mm) - T1 6 36.0083 1.76436 1.376 0.227

Maxilla (mm) - T2 6 36.2767 1.51191


Mandible (mm) - T1 6 27.7283 1.74809


Mandible (mm) - T2 6 28.2667 1.29915


Mandible (mm) - T2 6 28.2667 1.29915

Tables and Graphs

TABLE IVB. PAIRED SAMPLES T-TEST TO COMPARE MEAN

VALUES OF INTER PREMOLAR WIDTH BETWEEN T0,T1 & T2 IN

EACH GROUP :


Sample

Pair 1 Maxilla (mm) - T0 6 45.5967 2.84119 0.949 0.386

Maxilla (mm) - T1 6 46.2250 1.29536

Pair 2 Maxilla (mm) - T0 6 45.5967 2.84119 0.272 0.796

Maxilla (mm) - T2 6 45.7600 2.08179

Pair 3 Maxilla (mm) - T1 6 46.2250 1.29536 0.919 0.400

Maxilla (mm) - T2 6 45.7600 2.08179


Mandible (mm) - T1 6 38.7150 2.82849


Mandible (mm) - T2 6 38.8667 2.81435


Mandible (mm) - T2 6 38.8667 2.81435

Control

Pair 1 Maxilla (mm) - T0 6 45.4717 2.28963 6.534 0.001

Maxilla (mm) - T1 6 47.4617 1.98365

Pair 2 Maxilla (mm) - T0 6 45.4717 2.28963 5.838 0.002

Maxilla (mm) - T2 6 47.9550 2.02477

Pair 3 Maxilla (mm) - T1 6 47.4617 1.98365 2.419 0.060

Maxilla (mm) - T2 6 47.9550 2.02477


Mandible (mm) - T1 6 40.3650 1.43581


Mandible (mm) - T2 6 40.6567 1.51373


Mandible (mm) - T2 6 40.6567 1.51373

Tables and Graphs

TABLE IVC. PAIRED SAMPLES T-TEST TO COMPARE MEAN

VALUES OF INTER MOLAR WIDTH BETWEEN T0,T1,T2

IN EACH GROUP


Sample

Pair 1 Maxilla (mm) - T0 6 44.0900 2.51114 0.383 0.718

Maxilla (mm) - T1 6 44.3417 1.75065

Pair 2 Maxilla (mm) - T0 6 44.0900 2.51114 1.269 0.260

Maxilla (mm) - T2 6 45.6167 3.51761

Pair 3 Maxilla (mm) - T1 6 44.3417 1.75065 0.828 0.445

Maxilla (mm) - T2 6 45.6167 3.51761


Mandible (mm) - T1 6 39.0850 2.72118


Mandible (mm) - T2 6 39.2617 2.52716


Mandible (mm) - T2 6 39.2617 2.52716

Control

Pair 1 Maxilla (mm) - T0 6 45.3900 2.25904 0.859 0.430

Maxilla (mm) - T1 6 44.7900 3.06267

Pair 2 Maxilla (mm) - T0 6 45.3900 2.25904 0.083 0.937

Maxilla (mm) - T2 6 45.3533 2.58197

Pair 3 Maxilla (mm) - T1 6 44.7900 3.06267 2.103 0.089

Maxilla (mm) - T2 6 45.3533 2.58197


Mandible (mm) - T1 6 38.6117 2.11353


Mandible (mm) - T2 6 38.6517 2.20760


Mandible (mm) - T2 6 38.6517 2.20760

Tables and Graphs

TABLE IVD INDEPENDENT SAMPLES T-TEST TO COMPARE

MEAN VALUES OF INTER CANINE WIDTH BETWEEN SAMPLES

AND CONTROLS

Width Measure Group N Mean Std. Dev t-

Value

P-

Value

INTER

CANINE

WIDTH

Maxilla (mm) - T0 Sample 6 36.3500 2.19049 0.678 0.513

Control 6 35.4333 2.48659


Control 6 36.0083 1.76436

Maxilla (mm) - T2 Sample 6 36.8233 .97336 0.745 0.474

Control 6 36.2767 1.51191

Mandible (mm) - T0 Sample 6 27.2683 1.46477 0.998 0.342

Control 6 26.2167 2.12553


Control 6 27.7283 1.74809


Tables and Graphs

TABLE IVE INDEPENDENT SAMPLES T-TEST TO COMPARE

MEAN VALUES OF INTER PREMOLAR WIDTH BETWEEN

SAMPLES AND CONTROLS


Value

P-

Value

INTER

PREMOLAR

WIDTH


Control 6 45.4717 2.28963


Control 6 47.4617 1.98365


Control 6 47.9550 2.02477

Mandible (mm) -

T0

Sample 6 39.0417 4.58573 0.486 0.637

Control 6 38.0517 1.96486

Mandible (mm) -

T1

Sample 6 38.7150 2.82849 1.274 0.231

Control 6 40.3650 1.43581

Mandible (mm) -

T2

Sample 6 38.8667 2.81435 1.372 0.200

Tables and Graphs

TABLE IVF INDEPENDENT SAMPLES T-TEST TO COMPARE

MEAN VALUES OF INTER MOLAR WIDTH BETWEEN SAMPLES

AND CONTROLS


Value

P-

Value

INTER

MOLAR

WIDTH

Maxilla (mm) - T0 Sample 6

44.090

0 2.51114

0.943 0.368 Control

6 45.390

0 2.25904


44.341

7 1.75065

0.311 0.762 Control

6 44.790

0 3.06267


45.616

7 3.51761

0.148 0.885 Control

6 45.353

3 2.58197

Mandible (mm) - T0 Sample 6

39.058

3 3.86050

0.291 0.777 Control

6 38.541

7 2.00847


39.085

0 2.72118

0.336 0.743 Control

6 38.611

7 2.11353


39.261

7 2.52716 0.445 0.666

GRAPH 1

4.37

0.50

0.00

4.00

0.67

0.00 0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

Maxilla - T0 Maxilla - T1 Maxilla - T2 Mandible - T0 Mandible - T1 Mandible - T2

Me

an

va

lue

Mean Irregularity Index (mm) in Sample. Table No.Ib

GRAPH 2

3.17

0.58

0.00

4.75

1.17

0.00 0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00


Me

an

va

lue

Mean Irregularity Index (mm) in Control. Table No. Ic

GRAPH 3

4.37

0.50

0.00

4.00

0.67

0.00

3.17

0.58

0.00

4.75

1.17

0.00 0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00


Me

an

va

lue

Comparision of Mean Irregularity Index (mm). Table No.Id Sample

Control

GRAPH 4

10.67

8.00

10.67

8.00

18.67

13.33

11.33

13.33

11.33

24.67

0.00

5.00

10.00

15.00

20.00

25.00

30.00

Maxilla T0-T1 Maxilla T1-T2 Mandible T0-T1 Mandible T1-T2 Total time taken

Me

an

va

lue

Mean Time taken for Alignment Efficiency (Weeks). Table No. IIb Sample

Control

GRAPH 5

104.67 99.83

36.00 32.50

111.67 108.33

41.83 39.83

0.00

20.00

40.00

60.00

80.00

100.00

120.00

IMPA-PRE IMPA-POST Lower Incisor toNB-PRE

Lower Incisor toNB-POST

Me

an

va

lue

Comparision of Mean Torque Expression. Table No.IIIc Sample

Control

GRAPH 6

36.35 36.88 36.82

27.27 27.36 28.33

35.43 36.01 36.28

26.22 27.73 28.27

0.00

10.00

20.00

30.00

40.00

50.00

60.00


Me

an

va

lue

Comparision of Mean Inter Canine Width (mm). Table No. IVd Sample

Control

GRAPH 7

45.60 46.23 45.76

39.04 38.72 38.87

45.47 47.46 47.96

38.05 40.37 40.66

0.00

10.00

20.00

30.00

40.00

50.00

60.00


Me

an

va

lue

Comparision of Mean Inter Premolar Width (mm). Table No.IVe Sample

Control

GRAPH 8

44.09 44.34 45.62

39.06 39.09 39.26

45.39 44.79 45.35

38.54 38.61 38.65

0.00

10.00

20.00

30.00

40.00

50.00

60.00

Maxilla - T0 Maxilla - T1 Maxilla - T2 Mandible -T0

Mandible -T1

Mandible -T2

Me

an

va

lue

Comparision of Mean Inter Molar Width (mm). Table no. IVf Sample

Control

Discussion

Discussion

43

DISCUSSION

Self-ligating bracket system has gained immense popularity in the last

few years. The proponents of the system claim that the SLBs is more effective

and efficient than the Conventional bracket system. The low friction which is a

hallmark of the self ligating brackets is supposed to encourage faster

alignment, without taxing the anchorage, with less need for extraction and in

fewer appointments. Efficiency is said to be influenced by three key factors:-

efficiency of the mechanics used, decreased chair time per office visit, and

fewer appointments to complete treatment.61

The term “self-ligating bracket” (SL bracket) is used for those type of

fixed orthodontic brackets that incorporate a locking mechanism (such as a

ring, spring, or door mechanism) that holds the arch-wire in the bracket slot.34

Self-ligating orthodontic brackets have a relatively long history,

but their development can best be viewed against the background of an

almost universal use of metal and elastomeric ligatures. Elastomeric ligation

gives unreliable archwire control, there is force decays therefore, tooth control

is not optimal,19

both wire and elastomeric ligatures sometimes may become

displaced.19

The other drawbacks of elastomerics include high friction,

increased chair side time and an added oral hygiene challenge.58

Wire ligation

is better in every respect, but it is very time consuming, has inconsistent force

application and the wire ends can cause trauma to patient and operator.58

Discussion

44

In contrast to this, the self ligating brackets are supposed to offer a

number of advantages such as:-19

Secured Robust Ligation, Full Bracket

Engagement, Low Friction, Increased efficiency, Maintenance of Optimal Oral

Hygiene, Comfortable for the Patient and Longer appointment intervals10,21

Wire ligatures provide suitable robust ligation, whereas elastomeric ligatures

undergo force decay if left for too long without being renewed, which calls for

frequent patient recalls.21

A study by Harradine, did quantify the loss of

elastomeric ligatures, finding 15 lost ligatures in 25 consecutively seen

patients in a 12-month treatment period.42

Full Bracket Engagement is a great advantage if the arch wire can be

fully engaged in the bracket slot and maintained there with certainty.23

Most of

the self-ligating brackets have mechanisms to deliver this advantage and

would ensure full engagement of all archwires and eliminate the need to regain

control of the teeth when full engagement is lost.42

In a study by Mezomo,35

where canine retraction was done with 0.018-in stainless steel wires, self

ligating brackets were found to provide better rotational control of the canine

than conventionally ligated brackets.

Wire ligatures do not stretch to an extent that engagement once

achieved at ligation is subsequently lost, so they can meet this requirement.

Elastomerics are worse since they may frequently exert insufficient force to

fully engage even a flexible wire and on subsequent degradation of their

elastic property may cause a significant loss of engagement as the elastomeric

Discussion

45

stretches.23

Typically elastomeric chains and ligatures suffer more than 50%

degradation in force in the first 24 hours21

when tested under in vitro

experimental environments. Twin brackets with the ability to “figure 8” the

elastomerics are a significant help in this respect but at the cost of increased

friction.58

Wire ligatures produce substantially lower friction forces than

elastomerics.52

However, the forces generated by wire ligation still reach high

and very variable levels 42

relative to those force levels that are thought to be

optimal for tooth movement. Most tooth movements involve relative

movement between the arch wire and the bracket.

Friction produced between the bracket and the arch wire must be

overcome before the intended tooth-moving forces can have their effect.19

Frictional forces arising from the method of ligation offers additional

resistance to this relative movement. Correspondingly much higher forces

must be applied and this has two related potential effects that inhibit tooth

movement. First, the total effective force is much more difficult to assess and

is more likely to be undesirably higher than force levels best suited to create

the optimal biologic response. Second, the binding forces are higher both

between bracket and wire and also at the contacts between irregular adjacent

teeth. And such binding forces also inhibit the required relative movement.19

Friction is the only source of resistance to sliding, when drawing arch

wires through well-aligned brackets friction has consistently been measured as

Discussion

46

much lower in the self- ligating brackets than in the conventionally ligated

brackets.2,22,29,33,37,52,55,56,59

Studies typically report values of almost zero with self-ligating

brackets and values from 43 to 98 g per bracket for various elastomeric-arch

wire combinations.30

The original motive of developing self-ligating brackets was to speed

the process of arch wire ligation.22

Maijer R, Harradine et al have shown self-

ligating brackets to save up to 9 minutes per visit compared with wire ligation

and approximately 2 minutes compared with elastomeric ligation.21,52

Several consecutive case series studies have found that treatment with

self-ligating brackets was quicker, required fewer visits, and resulted in better

final alignment and occlusion than treatment with conventional appliances 6,62

Two recent systematic reviews have concluded that there is insufficient

evidence to support the view that treatment with self-ligating brackets results

in fewer visits or shorter treatment time. 43,54

Manufacturers claim that treatment with self-ligating brackets is less

painful and it has put forth two explanations: the forces on the teeth are lower

because lighter arch wires can be used with equal effectiveness, and the teeth

move more readily in response to the applied forces because of decreased

resistance to sliding.22

Discussion

47

Yamaguchi M et al, conducted a split-mouth study to examine the

measure of pain with the help of the level of the neuropeptidase substance P in

gingival crevicular fluid, which is a marker of inflammation and associated

pain resulting from orthodontic forces and, found that treatment with self-

ligating brackets significantly lowered the levels of Substance P and

inflammation when compared with conventional ligation at 24 hours after arch

wire placement.68

Repeated claims of more efficient treatment have been made; which

have been contradicted by the findings from few randomized trials.9,13,28

Similarly, there appears to be little basis for the claim that self-ligating

brackets induce distinctive arch dimensional changes.44

Padhraig S. Fleming

conducted a randomized controlled trial, and found no differences in

maxillary arch dimensional changes or molar and incisor inclination changes

after alignment with passive self-ligating brackets, active self-ligation, or

conventional brackets.44

Interest in self ligating brackets has grown in the recent years. There

are essentially two main types of self-ligating brackets, based on the designing

of the locking mechanism and the dimensions of the slot: active brackets and

passive brackets.

In passive systems (such as the Damon System. ORMCO, A Company,

Orange, CA), the slot is locked with a rigid locking mechanism. Once it is

engaged, the bracket is effectively turned into a tube, ideally allowing arch

Discussion

48

wires to slide freely within the tube.34

In active systems (such as Quick,

Forestadent Ltd., Germany; and SPEED, Cambridge), the locking mechanism

generally consists of a flexible but resilient clip that can actively engages the

wire into the bracket slot once the arch wire reaches a certain size of

deflection. 52?

Active self ligating brackets such as, SPEED (Strite Industries,

Cambridge, Ontario, Canada), and Quick brackets(Forestadent Ltd., Germany)

have a sliding spring clip, (type of clip search) which encroaches on the slot

from the labial aspect, potentially placing an active force on the arch wire.

These brackets are all correctly described as having potentially active clips. In

contrast, the passive self ligating brackets such as the Damon brackets

(ORMCO, A Company, Orange, CA) have a slide which opens and closes

vertically and creates a passive labial surface to the slot with no intention

or ability to encroach upon the slot and store force by deflection of a

metal clip.58

A third type of bracket system has been added called the Interactive

self ligating brackets such as the InOvation R bracket (GAC, International,

Bohemia, NY, USA) which can exhibit either passive or active properties

during any stage of treatment at the discretion and direction of the clinician.64

They exhibit minimal force and friction (passive) in the early stage of

treatment .Torque and rotational control (active) in the middle and finishing

stages of treatment.66

Discussion

49

In the search of a possible ideal Self Ligating bracket, a combination

bracket with both a spring clip and a passive slide was pondered upon. If low

resistance to sliding is desired, the passive slide could be used, and, if high

resistance to sliding is appropriate, then the active spring clip could be used.8

Gianelly reported that in the extraction space-closure method, with

crimp-on hooks and molars, the anterior brackets could have conventional

brackets or an Self Ligating active clip for 3D control, whereas the posterior

teeth could have passive Self Ligating brackets to reduce friction for space

closure by sliding.18

Based on this concept, the Dual Activation Self Ligating Bracket

system was introduced in the market by American Orthodontics. They have a

unique system wherein, the anterior brackets are of the Intractive while, the

posteriors are passive self ligating bracket system. It claims to passively hold

the smaller archwires and actively engage the larger dimensional wires for

lower ligation force in the early treatment stage with proper torque and

rotational control during working and finishing stages.

A number of factors in addition to bracket type might be expected to

influence the time for initial alignment of the labial-segment teeth, including

the degree of initial mal-alignment of arch, arch wire engagement, arch-wire

sequence, and the presence or absence of extraction spaces.17

Discussion

50

Very low classical friction with various designs of Self Ligating

brackets has been clearly demonstrated within the literature with passive

ligation being superior to active ligation in this regard.33

However, the

assumption has been made that along with low friction in vitro comes more

rapid alignment and a reduction in treatment time in vivo.33

P.G.Miles38

found

that during the initial alignment phase of treatment, the passive system had 0.2

mm greater irregularity index score, so clinically it did not perform any better

than the conventional twin bracket.

The aim and objective of our study, was to assess the alignment

efficiency with the Dual activation bracket system. To our knowledge, all the

current evidence as far as bracket types influencing the rapidity of alignment is

confined to either active, passive or interactive bracket systems. Hence, the

need to assess the efficiency of the Dual activation brackets was designed and

the results were compared with the efficiency of the Conventional Pre adjusted

edgewise system.

Our study used Dual activation self ligating bracket system with the

interactive brackets in the anterior and passive self ligating brackets in the

posterior teeth. This refers to the fact that round wires less than 0.020 inches in

diameter sit passively in the slots of the anterior brackets, with no force being

delivered from the clip or the fourth wall.19

Any arch wire with a bucco-

lingual dimension larger than 0.020 inches will receive a greater amount of

force from the actively displaced clip, thereby delivering exceptional torque

Discussion

51

and rotation control during working and finishing stages. Whereas , the

posterior passive brackets offers low ligation forces throughout all the stages

of treatment.

Studies done by Henao et al24

found that the bracket is passive for

0.014 inches and 0.016 inches wires and as the dimension of the wire

increased the clip actively engaged the wire into the slot. This is because the

horizontal gingival wall is reduced and therefore, the dimension is reduced to

0.019 inch width and not 0.028 inch. In this regard, the dual activation bracket

systems have a better three dimensional control compared to passive self-

ligation system. However, as noted, the passive self ligation brackets produce

less frictional force compared to active self ligating brackets.53

Some of the other claims made by the proponents of the passive self

ligation system is that a majority of cases can be treated without extraction.

The combination of low force and low friction along with altered

biomechanical response which supposedly widens the arches. Thereby,

eliminating or at the best reducing the need for extraction in borderline

extraction cases. The passive widening of the arches is also supposed to reduce

the possibility of incisors flaring thereby, offering excellent torque control.

Thus, this study was done to compare the alignment efficiency of Dual

activation self ligating brackets (Empower Dual Activation, American

Orthodontics, Sheboygan, WI,USA) and conventional bracket (MiniMaster

Series, American Orthodontics, Sheboygan, WI,USA); along with changes in

Discussion

52

transverse dimensions and the torque expression between both the bracket

systems.

The alignment efficiency was assessed by using the Little’s Irregularity

Index50

measured on the study models of both upper and lower arches. In

addition, changes in arch width by using dental casts was also studied;

mandibular incisor inclination was measured from cephalometric lateral skull

radiographs.

There is a relative lack of evidence comparing the efficiency of SL and

CL brackets in extraction patients because most studies have investigated

mixed samples. Only 2 clinical trials have compared SL and CL brackets

solely in extraction patients.39,49

The prospective study included Sixteen subjects, with total number of

ten female subjects and six male subjects with mean age of 16.8±4 years

having only permanent dentition with Angle's class I Malocclusion or Bi-dento

alveolar malocclusion. The subjects were randomly divided into Group A and

Group B. Patients were selected based on their irregularity index scores of

≥ 4mm requiring all first bicuspid extractions. At the start of treatment four

subjects were eliminated from the study due to failure to keep up with the

appointments.

Plaster study models and lateral cephalometric radiographs were taken

at three time points: before the start of the treatment (T0), at the time of

Discussion

53

placement of 0.018 inch stainless steel wire (T1) and at the time of placement

of a 0.019 x 0.025 inch stainless steel wire which sits passively in the

arches (T2).

The treatment began with an initial archwire of 0.016-in round thermal

nickel titanium (Type III arch form, American Orthodontics,

Sheboygan,WI,USA), followed by 0.018-in- stainless steel (Type III arch

form, American Orthodontics, Sheboygan,WI,USA) ; then 0.019 x 0.025 in

nickle titanium wire (Type III arch form, American Orthodontics,

Sheboygan,WI,USA) followed by 0.019 x 0.025 in-stainless steel wire (Type

III arch form, American Orthodontics, Sheboygan,WI,USA). The patients

were reviewed every 4 weeks; and the first archwire/ all the archwires was left

in place until the teeth were passively engaged in all bracket slots before

proceeding to the second archwire. The total time taken from the time of

bonding T0 and advancing to T2 were noted in weeks to check for the

efficiency of the brackets.

The treatment efficiency of the Dual activation self ligating brackets

are discussed under the following headings:-

Alignment efficiency

Amount of Arch Expansion

Torque expression.

Discussion

54

Non Parametric Mann Whitney test was done to assess the amount of

difference in the irregularity score between the sample and the control in the

mentioned time frames. A Wilcoxon signed ranked test was done to evaluate

the alignment efficiency between the sample and the control.

Alignment efficiency:

All study models were evaluated by using Little’s irregularity index50

to quantify the alignment of the six anterior teeth. The study models were

evaluated using a digital vernier caliper over three time frames. The

measurements were made in duplicate, and the average of the 2 readings was

taken to a resolution of 0.01 mm.44

The time frames were as: T0 was at the

beginning of the treatment; followed by T1 which was at the time of

placement of a 0.018 inch stainless steel wire and T2 was at the time of

placement of a 0.019 x 0.025 inch stainless steel wire.

The results showed that although the irregularity score was high for the

sample at the start of the study, there was no statistical significant difference

between the sample and the control at T1 and T2 indicating rapid treatment by

the self ligating bracket system. The alignment time taken for maxillary and

mandibular arches between T1 to T2 which shows that Self ligating brackets

has faster initial alignment than the conventinal group with a mean difference

of 3.3 weeks. A statistically significant difference of 6 week was seen in the

total time taken showing lesser time taken for alignment in the Self ligating

group.

Discussion

55

In a study by Pandis et al45

moderate crowding of < 5 was alleviated

about 2.7 times faster with Self ligating brackets than with conventional

appliances. This difference could be because of the substantially greater free

play of the self-ligating brackets, an effect that facilitates unhindered labial

movement of the crown. Whereas , an elastomeric module or steel ligatures act

as obstacles because of the stress they exert on the wire adjacent to the bracket

sides, precluding free sliding of the wire into the slot walls and adversely

affecting movement rate.45

For moderate crowding with an irregularity index of ≤ 5 mm, there is

some evidence that the self ligating brackets can produce faster alignment,

although this becomes marginally insignificant for more severe crowding.45

The combination of low friction and secure full engagement is particularly

useful, in the alignment of very irregular teeth and the resolution of severe

rotations, where the capacity of the wire to slide through the brackets of the

rotated and adjacent teeth significantly facilitates alignment. This relationship

between friction and derotation has been described and quantified by Koenig

and Burstone,4 and the potential adverse forces shown to be very large. Low

friction, therefore, permits rapid alignment and more certain space closure,

whilst the secure bracket engagement permits full engagement with severely

displaced teeth and full control, whilst sliding teeth along an archwire.

The treatment times in both groups in this study were comparable with

average orthodontic treatment time. Statistically significant difference is seen

Discussion

56

in the total time taken showing lesser time taken for alignment in the Self

ligating group. Therefore, accounting for confounding pretreatment and in-

treatment factors, in our sample the use of self-ligated brackets offered mild

advantage in reducing treatment time for initial alignment. The claims22

relating to treatment efficiency of the Self ligating bracket have been justified

by our investigation. Advocates of this appliance emphasized the importance

of the clinicians embracing this philosophy, allowing the light-force, low-

friction system to achieve physiologic adaption, aligning crowded arches and

avoiding the use of auxiliaries, such as headgear or palatal expansion devices.

In our study, all patients had first premolars extracted, and none of the samples

had anchorage reinforcement at any stage during treatment.

Transverse dimensional changes:

Inter canine widths and Inter second premolar widths were measured

from the cusp tips of the canines and second premolars. Measurements were

not taken from the gingival margin because the quality of the gingival

impression was inconsistent. Inter molar widths were measured from the

central and mesial occlusal pits of the mandibular and maxillary first molars

because this area of the impression was clearer than the cusps.11.

All

measurements were done using digital Vernier caliper with sharpened tips that

were accurate to 0.01 mm.

Discussion

57

In this study, no statistical significant difference was found between the

two groups for inter canine, inter second premolar and inter molar widths

which showed that no arch expansion has taken place.

Padhraig S. Fleming 44

observed that significant changes occurred in

the premolar region with up to 4.51 mm of expansion with Damon Q in the

first premolar region. The changes were slightly greater than those reported by

Franchi et al 16

in a prospective follow-up of 20 patients treated with fixed

appliances with low-friction ligatures over the initial six months of treatment.

Franchi et al reported that expansion ranging from 1.71 to 3.65 mm for

maxillary transverse dimensions with increases peaking in the premolar

region. The reasons for relatively large dimensional increases in Fleming’s44

study can be related to the use of Damon archwires, whereas Tru-arch medium

form wires were used by Franchi et al. Its a known fact, that Damon arch

wires have a broad arch form shape, particularly in the buccal segments, and

that could have contributed to the amount of expansion reported.44

Moreover,

a previous randomized study by Cattaneo et al40

had combined the use of

Damon wires and brackets, but the narrower wires with active self-ligating

brackets, reported similar levels of first premolar expansion with mean values

of 4.5 and 4.3 mm in the active and passive groups, respectively. Slightly

greater amounts of inter molar (0.9 mm) and inter second premolar expansion

(0.7 mm) were noted with the Damon system, however, suggesting that any

effect of the broadened archwire might be exerted farther posteriorly.

Discussion

58

Torque expression:

Angular changes in axial inclination of the long axis of the mandibular

incisor relative to the mandibular plane were measured by assessing the lateral

cephalograms. Radiographs were traced and measured as serial pairs.

Results showed no statistically significant difference in the amount of

torque expression of mandibular incisor in both linear and angular

measurements.

N. Pandis, S Strigou, T Eliades65

tested the hypothesis that the

engagement mode of wire to bracket affects the buccolingual inclination of

maxillary incisors in extraction and non extraction treatment with self ligating

and conventional brackets and they concluded that self ligating brackets seem

to be equally efficient in delivering torque to maxillary incisors relative to

conventional brackets in extraction and non extraction cases.

Studies have depicted mandibular incisor proclination in both self

ligation and conventional groups had no statistical significant difference [Jiang

and Fu,27

; Scott et al.,49

; Fleming et al.42

;Pandis et al46

], indicating that the

mechanism for relieving crowding involves incisor proclination and transverse

expansion through tipping of posterior teeth, which is similar for conventional

and self-ligating brackets. A study by Cattaneo et al.40

, using CBCT was done

to compare the labio lingual inclination of mandibular incisors relative to the

Discussion

59

occlusal plane between active and passive self-ligating brackets and confirmed

a significant proclination of mandibular anterior teeth, thereby rejecting the

claim of torque control by self-ligating systems The meta-analysis including

three of these studies showed that self-ligating brackets had 1.5 degrees less

proclination that was statistically significant, although it may not be a

clinically significant change.63

The present study evaluated the efficiency of self ligating brackets and

conventional brackets only in the transverse plane and sagittal plane. Vertical

changes have not been addressed. Other possible confounding factors could

include the lack of using a cone beam CT to evaluate the arch width changes

and the cortical bone thickness in terms of expansion. Moreover, it has been

postulated that light continuous forces with reduced friction produces 1.8

times greater tooth movement compared to light dissipating or heavy forces.67

Therefore, further studies with more sample size and CBCT scans are

needed to investigate the transverse dimensional changes of dual activation

self ligating brackets compared to conventional brackets and their overall

treatment efficiency.

Summary and Conclusion


60

SUMMARY AND CONCLUSION

The purpose of this study was to determine the alignment efficiency of

Self Ligating brackets compared to the conventional bracket system.

Twelve consecutive patients who met the selection criteria were

included in the study from a pool of patients satisfying the following inclusion

criteria: all first bicuspid extraction in the maxillary and mandibular arches;

permanent dentition; irregularity index of greater than 2 and no therapeutic

intervention planned with any other extra oral or intra oral appliance. The

patients were randomly divided into two groups of six each- SLB group

(Empower Dual Activation, American Orthodontics, Sheboygan, WI,USA)

and Conventional group (Mini Master Series, American Orthodontics,

Sheboygan, WI,USA), both with Roth 0.022 –in slots. The irregularity index

of both maxillary and mandibular arches were normalized between the groups,

and the time taken for alignment was estimated in weeks. The time points of

the protocol were set as T0-start of the treatment; T1- at the time of placement

of 0.018-in stainless steel arch wire; T2- at the time of placement of 0.019 x

0.025-in stainless steel arch wire passively in the arch. Study models were

taken at each of the time points. Treatment duration was assessed by data

modeling with the Mann Whitney U test. Lateral cephalometric radiographs

were used to assess the alteration of mandibular incisor position before and

after alignment. Measurements of inter canine, inter second premolar and inter

molar widths were also made on the dental study models to evaluate the


61

transverse dimensional changes associated with the bracket systems. Paired T-

Tests were used to assess the torque expression and the transverse changes

between the two groups. The tests suggested that there was statistical

significance in torque expression between pre and post alignment and no

changes was observed in inter canine, inter second premolar and inter molar

regions.

The following conclusions can be made from the present study:

1. There was a statistically significant difference in the initial alignment

between the dual activation system and the conventional bracket

system, where the dual activation system showed rapid alignment in

the maxillary and mandibular arches.

2. No difference in the quantum of transverse dimensions was observed

between the dual activation system and the conventional system in the

regions of inter canine, inter premolar and inter molar.

3. No difference was noted in the amount of anterior torque expression in

between the two bracket systems.

The limitations of the study are the fact that the sample size needs to be further

enhanced to assess the amount of arch expansion brought about by the self

ligation system and the lack of Cone Beam CT decreases the strength of the

study as a clearer picture of the amount of change seen in the buccal and

palatal cortical bone thickness would reveal us the amount of expansion

achieved by the bracket systems.

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