LEVELING AND LEVELING AND ALIGNINGALIGNING

DR JASMINE ARNEJA PRECEPTORDR SHALAJ BHATNAGARDR DIVYA

CONTENTS:CONTENTS:

GOALS OF THE FIRST STAGECHOICE OF ARCHESALIGNMENT IN SYMMETRIC CROWDINGALIGNMENT IN ASYMMETRIC ARCHESCROSSBITE CORRECTIONUNERUPED TEETHDIASTEMA CLOSURELEVELING BY EXTRUSIONLEVELING BY INTRUSION

According to Raymond Begg, the major

stages of comprehensive orthodontic treatment are ;

alignment and leveling, correction of molar relationship and space

closure, finishing. Tooth leveling and aligning is normally

the first orthodontic objective during the initial stage of treatment.

GOALS OF THE FIRST STAGE OF GOALS OF THE FIRST STAGE OF TREATMENTTREATMENT

In almost all patients with malocclusion, at least some teeth are initially malaligned.

The great majority also have either excessive overbite, resulting from some combination of an excessive curve of Spee in the lower arch and an absent or reverse curve of Spee in the upper arch,

or (less frequently) anterior open bite with excessive curve of Spee in the upper arch and little or none in the lower arch.

The goals of the first phase of treatment are to bring the teeth into alignment and correct vertical discrepancies by leveling out the arches.

For proper alignment, it is necessary not only to bring malposed teeth into the arch, but also to specify and control the anteroposterior position of incisors, the width of the arches posteriorly, and the form of the dental arches.

Similarly, in leveling, it is important to determine and control whether leveling occurs by elongation of posteriors, intrusion of anteriors or a combination of these two

Current Trend :Current Trend :In the past the usual method of

regulating the magnitude of force from an orthodontic appliance was primarily variation in the cross sectional dimensions of the wires used. Although configurations such as loops have been used to lower forces, small wires were used for light forces and large wires for heavier ones. Hence traditional orthodontics may be described as "variable cross section orthodontics".

Further development of materials in orthodontics was influenced by the orthodontist's demands to have appliance systems that were relatively resistant to permanent deformation, thus providing a large range of activation. This blend of characteristics required the use of materials that had high yield strength to elastic modulus ratio, as demonstrated by NiTi and TMA. With the introduction of these materials to orthodontics, a new clinical strategy evolved, namely the "variable modulus orthodontics".

The generation of superelastic and thermodynamic nickel-titanium wires like neo-sentalloy, Cu-NiTi, etc, represents another major advance from the previous concepts.

By taking advantage of the body temperature, and by setting the alloy's transformation temperature for the martensitic transformation, precise control of the memory phenomenon can be effected. This is called "variable transformation temperature orthodontics".

WIRE SEQUENCE WIRE SEQUENCE ACCORDING TO ACCORDING TO DIFFERENT DIFFERENT ORTHODONTIC ORTHODONTIC CONCEPTS :CONCEPTS :

ALIGNMENT ALIGNMENT

In nearly every patient with malaligned teeth, the root apices are closer to the normal position than the crowns, because malalignment almost always develops as the eruption paths of teeth are deflected.

To bring teeth into alignment, a combination of labiolingual and mesiodistal tipping guided by an arch wire is needed, but root movement usually is not.

Several important consequences for orthodontic mechanotherapy follow from this :

Initial arch wires for alignment should provide light, continuous force of approximately 50 grams, to produce the most efficient tipping tooth movement. Heavy force, in contrast, is to be avoided.

The arch wires should be able to move freely within the brackets. For mesiodistal sliding along the archwire, atleast 2 mil clearance is needed, 4 mil is desirable and beyond that provides no advantage.

This means that the largest initial arch wire that should be used with an 18-slot edgewise bracket is 16 mil, whereas 14 mil would be more satisfactory. With the 22 slot bracket, an 18 mil arch wire would be close to ideal from a bracket clearance point view.

Rectangular arch wires, particularly those with a tight fit within the bracket slot so that the position of the root apex could be affected, normally should be avoided.

 A, Diagrammatic representation of the alignment of a malposed lateral incisor with a round wire and clearance in the bracket slot. With minimal moments created within the bracket slot, there is little displacement of the root apex. B, With a rectangular archwire that has enough torsional stiffness to create root movement, back-and-forth movement of the apex occurs before the tooth ends up in essentially the same place as with a round wire. This has two disadvantages: it increases the possibility of root resorption, and it slows the alignment process.

The springier the alignment arch wire, the more important it is that the crowding be at least reasonably symmetric. If only one tooth is crowded out of line a rigid wire is needed that maintains arch form except where springiness is required, and an auxiliary wire should be used to reach the malaligned tooth.

PROPERTIES OF ALIGNMENT PROPERTIES OF ALIGNMENT ARCHWIRESARCHWIRES

The flat load deflection curve of superelastic NiTi makes ideal for initial alignment. Under most circumstances initial alignment can be accomplished simply by tying 14 or 16 mil A-NiTi that delivers about 50 gm into the brackets of all the teeth.

NITI has the property of delivering light forces over a long range

Other options are ◦multistranded niti---lower force values

with and higher fracture resistance◦Copper niti- 15, 27, 35, 40◦Bioforce- graded thermodynamic niti

Alignment in Premolar Alignment in Premolar Extraction SituationsExtraction Situations In patients with severe crowding of

anterior teeth, it is necessary to retract the canines into premolar extraction sites to gain enough space to align the incisors. In extremely severe crowding, it is better to retract the canines independently before placing attachments on the incisors. Sliding the canines produces more stress on the posterior anchorage, so critical anchorage is an indication for the retraction loops.

In more typical and less extreme crowding, it is possible to simultaneously tip the canines distally and align the incisors. The same independent distal movement of the canines now can be obtained with an A-NiTi arch wire, and A-NiTi coil springs from the first molars or active tiebacks to tip the canines distally. When this is done, the spring should be chosen to deliver only 50 gm, and an arch wire preformed by the manufacturer to have an exaggerated reverse curve of spee should be chosen, to limit forward tipping of the molars.

Alignment in Non-extraction Alignment in Non-extraction SituationsSituations ::

Alignment in non extraction cases requires increasing arch length, moving the incisors further from the molars. In this circumstance, just tying a superelastic wire into the bracket slots is ineffective.

Crimp a stop ahead of the molars

Don’t cinch back

Alignment of Asymmetric CrowdingAlignment of Asymmetric Crowding

If a niti archwire is tied into an asymmetrically maligned arch, teeth distant to the site of malalignment will be moved

Tie superelastic wire as an auxilliary to a heavier wire

ANCHORAGE CONTROL ANCHORAGE CONTROL DURING LEVELING AND DURING LEVELING AND

ALIGNINGALIGNING

LACEBACKS FOR A/P CANINE LACEBACKS FOR A/P CANINE CONTROLCONTROL

Lace backs are 0.010 or 0.009 ligature wires which extend from the most distally banded molar to the canine bracket. They restrict canine crowns from tipping forward during leveling and aligning.

The initial purpose of lace backs was to prevent canines from tipping forward, but it was observed that, where necessary, these ligature wires were an effective method of distalizing the canines without causing unwanted tipping

Lace backs are normally continued throughout the leveling and aligning arch wires sequence. .

BENDBACKS FOR A/P INCISOR BENDBACKS FOR A/P INCISOR CONTROL :CONTROL :

If the arch wire is bent back immediately behind the tube on the most distally banded molar, this serves to minimize forward tipping of incisors.

In cases where it is necessary to increase arch length during leveling and aligning and where A/P incisor control is not required, bend backs should be placed 1 or 2 mm distal to molar tubes.

A/P ANCHORAGE SUPPORT AND A/P ANCHORAGE SUPPORT AND CONTROL FOR MOLARSCONTROL FOR MOLARS

HeadgearsTPA- only for transverse and

rotation controlNance palatal archLingual arch

Vertical Control of the IncisorsVertical Control of the Incisors The effect of bracket tip is more extreme in the upper

arch, and care is needed if the canines are distally tipped in the starting malocclusion.

In such cases, as the arch wire passes through the canine bracket slot it will lay incisally to the incisor bracket slots. If the wire is fully engaged into the incisors, it will tend to cause extrusion of these teeth, which is undesirable in most cases.

This effect can be avoided either by not bracketing the incisors at the start of treatment, or by not tying the arch wire into the incisor bracket slots, but allowing it to lay incisally to the brackets until the canine roots have been uprighted and moved distally, under the control of the lace backs. The incisors can then be engaged without causing unwanted extrusion.

SPECIAL PROBLEMS IN SPECIAL PROBLEMS IN ALIGNMENTALIGNMENT

Individual Teeth Displaced into Individual Teeth Displaced into Anterior CrossbiteAnterior Crossbite

Correction of the crossbite requires first opening enough space for the displaced teeth, then bringing them into proper position in the arch

It may be necessary to use a bite plate temporarily to separate the posterior teeth and create the vertical space needed to allow the teeth to move.

Correction of Dental Posterior Correction of Dental Posterior Crossbite :Crossbite :

Three approaches to correction of less severe dental crossbite are feasible :

a heavy labial expansion arch, an expansion lingual arch, or cross elastics. Removable appliances, although

theoretically possible, are not compatible with comprehensive treatment and should be reserved for the mixed dentition or adjunctive treatment.

Minimal molar crossbite can usually be corrected in the final stage of leveling and aligning using rectangular wires which are slightly expanded from the normal form.

The inner bow (36 or 40 mil) is simply adjusted at each appointment to be sure that it is slightly wider than the headgear tubes and must be compressed by the patient when inserting the facebow. The effect of the round wire in the headgear tubes, however is to tip the crowns outward, and so this method should be reserved for patients whose molars are tipped lingually.

If anchorage is of no concern, a highly flexible lingual arch, like the quad helix design, is an excellent choice for correction of a dental crossbite. When the lingual arch is needed for both expansion and anchorage, however, the choices are 36 mil steel wire with an adjustment loop.

The third possibility for dental expansion is the use of cross-elastics, typically running from the lingual of the upper molar to the buccal of the lower molar. These elastics are effective, but their strong extrusive component must be kept in mind.

Care is needed to avoid arbitrary

correction of molar crossbite by tipping movements. This allows extrusion of palatal cusps and unwanted opening of the mandibular plane angle in treatment of high angle, and even routine, Class II/I problems. Whenever possible, molar crossbite should be corrected by bodily movement.

Cases with Unerupted Teeth, Cases with Unerupted Teeth, or Teeth Significantly Out of or Teeth Significantly Out of

the Arch Formthe Arch Form

Such teeth can be left unbracketed until adequate space is provided for their movement and positioning. Once space is created, these teeth can be bracketed and lightly tied with elastic thread to the main arch wire. The creation of adequate space allows bodily movement of these teeth into the arch form and more correct root positioning, reducing the treatment needs in the finishing phase.

Surgical Exposure of Surgical Exposure of unerupted/impacted unerupted/impacted teeth:teeth:

It is important for a tooth to erupt through the attached gingiva, not through alveolar mucosa, and this must be considered when flaps to expose an unerupted tooth are planned.

Surgical Procedures: 2 basic types 1. Closed eruption – full thickness muco-periosteal

flap is raised and crown exposed, attachment is fixed & flap sutured back over crown leaving only a twisted wire passing through the mucosa to apply orthodontic traction

2. Open eruption:a) Punch incision is made on crown to make window &

cemented pack is placed on itAccording to Johnston, Gaulis & Joho:For Palatally impacted tooth: Closed eruption

indicatedFor Labially impacted tooth : Open eruption is

indicated with repositioned mucoperiosteal flap to avoid any future mucogingival problem (Vanarsdall &Corn)

Vanarsdall and Corn suggested that flap containing the keratinized tissue be placed to cover the CEJ & 2-3mm of crown

METHODS OF ATTACHMENT:1. Lasso technique2. Threaded posts3. Bonded brackets/ button4. Magnets

Mode of Traction:1. Ligature wire 2. Elastomeric chain3. Coil springs4. K9 spring 5. Elastic thread6. Killroy spring7. Cantilever spring8. Niti arch wire

Occasionally, an unerupted tooth will start to move and then will become ankylosed, apparently held by only a small area of fusion. It can sometimes be freed to continue movement by anesthetizing the area and lightly luxating the tooth, breaking the area of ankylosis. If this procedure is done, it is critically important to apply orthodontic force immediately after the luxation, since it is only a matter of time until the tooth re-ankylosis.

Midline diastema:Midline diastema:Diagnosis-Early fibrotomyLate fibrotomyRecommended

procedure by Edwards

LEVELING LEVELING

The correction of deep overbite involves :

Eruption / extrusion of posterior teeth. Distal tipping of posterior teethProclination of incisorsIntrusion of incisorsA combination of two or more of the

above tooth movements

INTRUSION OF ANTERIORSBurstone23 defined intrusion as, “Apical

movement of the geometric center of root (centroid) in respect to the occlusal plane or a plane based on long axis of the tooth.”

Intrusion of incisors is commonly indicated in pseudo deep bite cases or the cases with increased anterior face height.

It is also indicated in cases where there is an excessive gingival display during speaking or smiling.

2. EXTRUSION OF POSTERIOR TEETH20

Extrusion of posterior teeth is commonly indicated in patients with decreased lower anterior face height.

It is also indicated in true deep bite cases. If the incisal edges of the maxillary anterior

teeth are positioned above the inferior margin of upper lip, in these cases extrusion of posterior teeth is indicated.

Extrusion of molars of an average of 1mm results in 2 to 2.5 mm of bite opening.

PROCLINATION OF INCISORSNumerous deep bite cases present

with retroclinated incisors. Proclination of incisors is indicated

when there is an increased nasolabial angle and retruded lip.

So soft tissue should be evaluated before proclinating the incisors.

NON-EXTRACTION TREATMENT :NON-EXTRACTION TREATMENT :

Non-extraction treatment generally favors bite opening. This is because distal tipping of posterior teeth and proclination of incisors normally occurs in these cases. There are a number of mechanical factors that lead to arch leveling and control of the deep overbite.

Initial Arch wire PlacementInitial Arch wire Placement When flat arch wires are placed into

dental arches with curves of Spee, the arch wires attempt to return to their original shape and this starts the bite-opening process. Also, expression of the tip in the brackets begins the bite opening process.

The Bite Plate Effect :The Bite Plate Effect : Introducing the bite plate effect in

deep bite cases is helpful in the bite opening process in three ways :

It allows for early placement of brackets on lower incisors, which begins their movement.

Anterior bite plates can produce an intrusive force on lower incisors which limits any future extrusion of these teeth.

Anterior bite plates allow for the eruption, extrusion, and/or uprighting of posterior teeth.

METHODS: Anterior bite

plane Direct bonding

material on upper incisors

Occlusal blocks

Bite-Opening Curves :Bite-Opening Curves :In the great majority of cases after

rectangular stainless steel wires have been in place for 6 weeks, the arches are normally level and adequate bite opening has been achieved. If this is not so, then bite opening curves can be placed into the rectangular steel wires.

Auxilliary leveling arch- 0.017x Auxilliary leveling arch- 0.017x 0.025 ss0.025 ss

LEVELING BY LEVELING BY INTRUSIONINTRUSION

Burstone in 1977, suggested 50 gram of intrusive force for upper central incisors, 100 gram force for centrals and laterals and 200 gram for six upper anteriors. He advocated use of 40 gram for four lower incisors and 60 gram for all six lower anterior intrusion.

Ricketts in 1980 advocated the use of 125 gram to 160 gram of force for upper incisor intrusion and 60 to 75 gram for lower incisors.

Karanth and Shetty in 2001 advocated 60 gram of force for four upper incisors and 100 gram of force for six anteriors; where as 40 gram of force for lower four incisors and 80 gram for six lower incisors.

Thus the force ranges on an average from 15 - 20 gm for each upper incisor and 10 - 15 gm for each lower incisor.

Bypass ArchesBypass Arches : : This approach to intrusion is most

useful in patients who will have some growth (i.e. who are in either the mixed or early permanent dentitions). This is based on the same mechanical principle : uprighting and distal tipping of the molars, pitted against intrusion of the incisors.

Intrusion arches:

Antero-Posterior Issues and Antero-Posterior Issues and Elastics :Elastics :

Inter-maxillary elastics can contribute to the bite-opening effect by assisting in the extrusion of molars as the A/P problem is corrected. They are beneficial in the treatment of most growing patients. If possible they should be avoided in most non-growing and adult high angle cases.

SKELETAL ANCHORAGESKELETAL ANCHORAGEMiniscrews Absolute anchorageIncisors to be tied back to prevent

tipping

Quick facts:Quick facts:

Photobiomodulation  (The surface of the cheek irradiated with near-infrared light with a continuous 850-nm wavelength and a power density of 60 mW/cm2 for 20 or 30 min/day or 60 min/week) has shown to hasten leveling and alignment

(Kau et al. Progress in Orthodontics 2013, 14:30 ) 

Quick facts:Quick facts:

Nagar et al proposed a modification in the K9 spring to prevent lingual tipping of molars (Contemporary Clinical Dentistry, Vol. 5, No. 2, April-June, 2014, pp. 272-274)

No stastical difference was seen in the leveling and aligning phase with self ligating and conventional brackets. (Comparison of self- and conventional-ligating brackets in the alignment stage. Wahab, EJO, 2011)

Pain exprienced in the first phase was rather more during archwire removal and insertion in the SLB group than in the CB group. (Pain Experience during Initial Alignment with a Self-Ligating and a Conventional Fixed Orthodontic Appliance SystemA Randomized Controlled Clinical Trial. P. S. Fleminga. The Angle Orthodontist: January 2009, Vol. 79, No. 1, pp. 46-50.)

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