Over dentures/ orthodontic straight wire technique

OVER DENTURES

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com

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INTRODUCTIOININTRODUCTIOIN

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• It is recognized that, this technique helps reduce impact of some of complete denture wearing consequences like :-

• Residual ridge resorption;

• Loss of occlusal stability;

• Undermined esthetic appearance

• Compromised masticatory appearance


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04/13/235

REGARDED AS A FORM OF PREVENTIVE THERAPY.

PREVENTIVE

PROTHODONTICS


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DEFINITION:

A removable partial denture or complete denture that covers and rests on one or more remaining natural teeth,the roots of the natural teeth,and/or dental implants.

A prosthesis that covers and is partially supported by natural teeth ,natural tooth roots and/or dental implants.


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THIS IS ALSO CALLED AS

• OVERLAY DENTURE.

• OVERLAY PROSTHESIS

• SUPERIMPOSED

PROSTHESIS


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• IMPORTANCE OF THE OVER DENTURE.

.

• NEUROMUSCULAR CONTROL &TACTILE DISCRIMINATION.

• ROOT PREPARATION.

• DIFFERENT TYPES OF ATTACHMENTS.


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ROOT PREPARATION :

• PLANING OVER DENTURES.

• SELECTION OF THE ABUTMENTS.

• SPACE REQIREMENTS.

• BARE ROOT FACE.

• PRECIOUS METAL COPINGS

• METHODS OF RETENTION.


04/13/2310

IMPORTANCE OF THE OVER DENTURES:

• PSYCHOLOGICAL BENEFITS TO THE PATIENTS.

• THE EFFECT UPON THE EDENTULOUS RIDGE.

• TACTILE DISCRIPTION.

• IMPROVED STABILITY AND RETENTION OF THE PATIENT.


04/13/2311

PSYCHOLOGICAL BENEFIT TO THE PATIENT.



04/13/2313

EFFECT UPON EDENTULOUS RIDGES

REVIEW LITERATURE:

In 1967&1969 TALLGREN showed that reduction of anterior height of mandibular ridge was 6 times greater than maxillary residual ridge.

2.Mean loss of mandibular ridge was 6.6mm &maxillary ridge is 1.6mm.


04/13/2314

• Where as bone loss in partially edentulous ridges in lower jaw is 0.8 and he showed that wide & unpredictable range of resorption pattern found in patients 3-6months after complete denture insertion


04/13/2315

• CRUM & ROONEY (1978) :retaining of mandibular canines for over dentures helped to preserve the remaining edentulous ridge.

• An interesting finding was that patients with remaining canines lost less ridge height in region between the canines than those without any natural teeth.


04/13/2316

• CRUM(1978):

• In a 5 years study patients wearing over denture lose about 8 times less bone than those with complete denture in the anterior region.


04/13/2317

• LORD &TEEL (1974)

They stressed that “teeth that are too weak for normal partial dentures abutments may be suitable for over denture.”

This type of approach was particularly recommended when denture was opposed by natural teeth.


04/13/2318

• WICAL & BRUSSEE(1979):

• He claimed that alveolar ridge resorption can be reduced for patient with immediate replacement denture by means of supplemental calcium & vit.D


04/13/2319

NEURO MASCULAR CONTROL & TACTILE DISCRIMINATION

• There differences between subjects with complete denture and over dentures in neuro physiology.

• Over dentures may impart a mechanical stability which itself enables an improved neuromuscular performance by the subjects.

• Enhanced perception of occlusal forces improves the subject ability to grade them because of the proprioreception.www.indiandentalacademy.com

04/13/2320

• The stability offered by an over denture might be expected to provide a more resistant platform for the generation of the force by masticatory musculature.

• There is difference between interocclusal force that is given by over denture patients &complete denture patients. Stable occlusal foundation gives more inter occlusal force than the unstable one


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• Preservation of the periodontal input providesneuro physiological bonus to the over denture patients.

• This proproception is due to mechanoreceptors that are present in the gingiva alveolar bone & periosteum


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PERIODONTAL TREATMENT FOR THE OVER DENTURE PATIENTS:

• Plaque score has to be taken.

• This provides the base line for the evaluation of the oral hygiene on ongoing treatment plan &patient motivation.

• A color coded periodontal probe should be used to plot the pockets depths on mesial distal ,buccal& lingual sides.


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DIAGNOSIS

• Clinical &radiographic examination has to be established to examine the gingiva & alveolar bone


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PROGNOSIS• The roots that are remain beneath the

over denture should be spaced out around the dental arch.

• Where the adjacent roots retained prognosis is less satisfactory.

• Canine teeth provide the most frequent abutment beneath the over dentures

• Canines are usually amongst the last teeth lost due to periodontal disease


04/13/2325

IDEAL REQUIREMENTS OF THEABUTMENTS FOR OVER DENTURES

• The gingival tissue should be firm,pink &tightly attached to the neck of the tooth &underlying bone

• A sufficient level of alveolar &supporting bone should remain free from angular bony defects.

• The abutments should be definitely root filled and free from caries.

• The abutments should exhibit a minimal degree of mobility once they have been sectioned 2-3mm above gingival marginwww.indiandentalacademy.com

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SEQUENCE OF TREATMENT:• Emergency care

• Disease control

• Extraction of badly decayed teeth

• Transitional partial dentures

• Endodontics

• Periodontal surgery

• Waiting period for the maturation of the tissues

• Construction of the over dentures.www.indiandentalacademy.com

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PRELIMINARY PERIODONTAL TREATMENT

• SCALING

• ROOT PLANNING

• PLAQUE CONTROLwww.indiandentalacademy.com

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CORRECTIVE PERIODONTAL THERAPY• The depths remain following preliminary

periodontal treatment corrective procedure are required.

• The periodontal tissues beneath over denture may be at greater risk than those around normal teeth' due to build up of the plaque &irritation that may occur from movement of the denture base under these conditions,pocket correction procedure may break down the reformation of the pocket depth.


04/13/2329

POCKET ELIMINATION PROCEDURES

• An internal bevel incision carried out around the abutment teeth using no.15 blade just apical to the gingival margin.

• “tramline”incisions are used along the crest of the ridge.once the incision has been completed the full thickness flap is then detached from the underlying bone


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• In order to position the flap apically the dissection must be carried a sufficient distance to allow the flap to drape it self without blanching ,when it its positioned with its gingival margin just coronal to the alveolar crest

• Buccal side often possible to use the split thickness flap


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PLANNING FOR OVER DEUTURES:

1.PERIODONTAL CONSIDERATIONS OF THE OVER DENTURE.

2. TOOTH LOCATION.

3. ENDODONTIC COSIDERATIONS

4. NO.OF OVERDENTURE ABUTMENT TEETH.

5. THE AMOUNT OF SPACE BETWEEN THE ABUTMENTS

6.SPACE REQUREMENTS.

7.BARE ROOT FACE.www.indiandentalacademy.com

04/13/2332

Periodontal considerations• Reducing the tooth to the gingival level

drastically reduces the leverage forces.

• As a rule of thumb, where 1/3rd of the root remain in the bone will not withstand the significant loads.

• Where the bone support is greater some lateral loads may be applied to provide essential stability to the prosthesis.



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TOOTH LOCATION:

• The canine regions are strategic positions for the over denture abutments.

• With regard to lower denture it is wise to select the teeth that can be joined by an imaginary line at right angles to the sagittal plane rather than provide a diagonal fulcrum line.



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ENDODONTIC COSIDERATIONS:

• Sound teeth with satisfactory root fillings must obviously be strong candidates for the abutments.

• Single rooted canal easier to root fill than multi rooted teeth.

• Multi rooted teeth with hemi section procedure are normally valuable in these areas.


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NO.OF ABUTMENTS:

• Two abutments on opposing side of the arch say, in canine regions will give excellent results.

• If more abutments are retained, it will complicate construction of the over denture.


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THE AMOUNT OF THE SPACE BETWEEN THE ABUTMENTS:

• Adjacent roots can complicate the plaque control &denture construction.

• If adjacent roots to be preserved,it is better to restore the individually .

• Connecting the root surfaces has several mechanical advantages like inclined loads resolved in more axial direction and there will be a marked resistance to loads with lateral and rotational components.



04/13/2340

SPACE REQUIREMENTSOver dentures tend to occupy more vertical space than the tooth substance that they replace.The reason is more bulk material is required for the strength of the denture base material

When additional components are added the space available is further reduced.

Buccolingual space &labiolingual space requirements also needs considerations.


04/13/2341

BARE ROOT FACES:

• Occlusal section of the root canal can be obturated with glass ionomer &silver amalgam.

• If the roots are curved highly polished surface can be produced to have following advantages: -

• It is the simplest cheapest &least space consuming solution.

• It is ideal solution during maturation of the edentulous ridges.

• This approach can also be used to evaluate the questionable abutments.


04/13/2342

COTRAINDICATIONS:

• It should not be used on along term basis .where natural teeth are indirect opposition.The incidence of longitudinal root fracture has been significantly raised

• It should not be used on long term basis unless a highly polished surface can be produced


04/13/2343

OCCLUSAL SURFACES

• In many respects porcelain is the ideal artificial occlusal surfaces both from point of view of appearance and function.

• porcelain require mechanical retention within the acrylic resin with denture base.

• This mechanical retention requires vertical space, a precious commodity where remaining roots are covered by a denture.

• The differing coefficient of expansion between porcelain acrylic resin increases likelihood of stress concentration around the artificial

• weakens the prosthesis.www.indiandentalacademy.com

04/13/2344

• The are certain advantages and disadvantages if porcelain over acrylic resin teeth.

• -porcelain is brittle material that chips cannot be used n cross section.

• Porcelain teeth are some what heavier than acrylic resin counterparts so that despite the complete denture use ,once over denture planned there are remarkably few situations in which porcelain occlusal surfaces can be employed.

• Acrylic resin teeth directly bonds to the denture base &the required Buccolingual is less than porcelain teeth.


04/13/2345

• The wear resistance of acrylic teeth is less compared to porcelain teeth.

• Wearing acrylic resin teeth with gold occlusal surfaces is in many respects the ideal arrangement it is particularly useful where acrylic teeth opposed by natural teeth surfaces.acrylic resin teeth have high rate of wear.


04/13/2346

Methods of retention• Borders seal always plays an important role in

retention

• Incase of over dentures simple copings are involved in the primary form of retention.

• The location and number of retainers also plays an important role .

• Excessive retainers complicate the construction of the prosthesis, they make plaque control more difficult and weakens the denture.

• Grip forces 300- 500gms/retainer gives adequate retention.


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• After the root preparation there different methods for obtaining retention &stability.

• 1.precious metal copings.

• Dome shaped copings.

• Attachments.


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PRECIOUS METAL COPINGS

• The wide variety of shapes &contours are available for to give the operator enormous scope with the design of the restoration.

• Gold copings can be used to impart the stability &retention.

• Crown &sleeve coping retainer similar to gold coping also gives the better retention &stability, but because of the rounded form denture will move when horizontal forces are applied.


04/13/2349

• C.This problem can be overcome by using inner&outer copings.

• The inner coping cemented on the tooth &the outer copings forms the part of the denture base.

• There are certain advantages &disadvantages of using acrylic outer copings.

• The degree of stabilization &retention can be controlled by the operator.

• it is comparatively easier to do the adjustments.

• if the copings has to be placed on the adjacent teeth it is difficult to place the metal copings because the proximal surfaces may interfere.

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• Another approach of making copings are simple thimble shaped copings.

• Thimble shaped copings needs considerable vertical &Buccolingual space further more this coping must be covered by adequate thickness of the denture base material.

• The retention obtained for the over denture will vary inversely with tape of the coping.

• The recommended height of the preparation is 4mm.

• This thimble shaped copings are particularly useful in the awkward distribution of the teeth.


04/13/2351

DOME SHAPED COPINGS.

• The height of the preparation for using dome shaped copings is 2mm above the ridge crest.

• Because of the mall size, lateral loads are reduced &spaced occupied is minimum.

• Their contribution to the retention of the prosthesis is negligible.

• This can be recommended where the thimble copings cannot be be used.

• Easier for the impression procedures&location procedures.

• This can be used for the immediate replacement of the over denture. www.indiandentalacademy.com

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• The design of the preparation is simple ,chamfer finish line is given.

• The design of the coping must be taken into account,the space available,and the forces that will withstand ,and must be contoured to facilitate the plaque control.

• The coping should be at least 1mm thick to with stand the forces.



04/13/2354

ATTACHMENTS

The third option available for the retention &stability of the over denture is using attachments.

• USES:prefabricated attachments provides considerable retention&stability.

• These attachments are normally midway between simple dome shaped copings &tall thimble shaped copings.

• A wide range of the attachments are available that range from traditional mechanical units to those which retention &stability is obtained by magnetic forces.


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• Employing attachments adds to the expense of the restoration.

• Attachments not only requires precise location between the various components,but may place additional forces on their dowels.

• Nevertheless in selected patients they give satisfactory results.


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ATTACHMENT SYSTEMS

• Stud attachments are simplest among the all attachments.

• The male part consists of stud shaped projection soldered to the diaphragm of dowel retained.

• The female part fits over the male unit & embedded within the denture base of the prosthesis.

• They are relatively small they can provide additional retention,stability &support.

• In inadequate vertical space,less bone support of the root these dome shaped copings are recommended.


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• They are of two types :

• 1.Extra radicular:-in which male elements projects from the root surface of the preparation.

• 2.Intra radicular:-in which the male element form the part of the denture base & engages a specially produced depression with in the root contour.


04/13/2358

USE OF ATTACHMENTS

• Prefabricated attachments are versatile and may provide considerable retention and stability.In some instances the additional retention may have dramatic effect on restoration.

• A variety of attachments are available that range from the traditional mechanical units to those in which retention and stabilization is provided by magnetic forces.


04/13/2359

• Stud attachments are particularly useful may have be divided into those extra radicular and projects from a diaphragm on root preparation and those that are intraradicular applies loads with in the root contour.

• The advantage of intraradicular attachments are –less vertical space is occupied by the attachment.

• Employing attachments adds to the expense of the restoration and felt that the load distribution to the abutments might not be so favorable through the attachments.


04/13/2360

• Attempting to seat oversized casting will result in vertical fracture of the root where as undersized castings result in less retention.

• Laboratory produced dowels are indicated for the unusual shape or angled roots .but the problems and difficulties cannot be underestimated.


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ATTACHMENT SYSTEMS

• Stud attachments are simplest among the all attachments.

• The male part consists of stud shaped projection soldered to the diaphragm of dowel retained.

• The female part fits over the male unit & embedded within the denture base of the prosthesis.

• They are relatively small they can provide additional retention,stability &support.

• In inadequate vertical space,less bone support of the root these dome shaped copings are recommended.


04/13/2362

• They are of two types :

• 1.Extra radicular:-in which male elements projects from the root surface of the preparation.

• 2.Intra radicular:-in which the male element form the part of the denture base & engages a specially produced depression with in the root contour.


04/13/2363

SELECTION OF THE ATTACHMENTS:• The rigid units,due to their small size are not

entirely immovable ,other units frequently allow more movement than should be ever required.

• Extra radicular stud attachments are relatively strong and can also provide retention than intra radicular attachments.

• Larger the attachments are relatively stronger than smaller ones and less prone to wear.

• The space availability will govern by the attachment selection.


04/13/2364

• The rigid units allow a neat good looking and retentive restoration to be made where four or more widely spaced and abutment remain.

• Cylindrical stud attachments produce tipping action on the abutments.

• Ball and socket attachments are started to produce four times more tipping action than the cylindrical attachments.

• Extra bracing of the roots may obtained by connecting them.

• The leverage effect of the root must be an important factor.


04/13/2365

NUMBER OF THE ATACHMENTS.One stud attachment on each side of the arch will

usually suffice ,other remaining roots can be covered with simple copings.

Increasing the no.of the attachments in a denture does not produce the corresponding improvement in the retention,it may contribute to improved stability,but this leads to weaken the prosthesis.


04/13/2366

CONNECTING ADJACENT COPINGS• Two stud attachments on adjacent roots are

seldom necessary.

• They would serve only weaken the prosthesis,complicate the plaque control.

• By this method rotational loads will be well resisted and the inclined forces resolves in the axial direction.


04/13/2367

--• The connection between the two copings will

need to be planned with some care.

• The contours of the connection should be self cleansable.

• It should not impinge on the tissues.

• This type of the attachment system particularly useful hen the level of the adjacent margins are about equal and there is at least 2-3mm between the roots.



04/13/2369

DIFFERENT ATTACHMENT SYSTEMS• DOLBO SUTD UNITS.

• The Dalbo ball &socket device is extremely popular it combines neatness &strength.

• They are of different types:

• Ball &socket

• The rigid Dalbo attachment.

• The Dalbo ball &socket is the simplest of all series

• It is 4mm height.

• It allows limited vertical &rotational movements.


04/13/2370

• It has spherical shaped male section that is easy to clean.

• The fingers of the socket is surrounded by nylon ring that simplifies the adjustments.

• In this series female units need simply be buried in the acrylic resin.

• Adjustments are easy to carry out and wear of the male unit seen if it is incorrectly aligned.

• The retention of the unit can be increased by altering the position of the lamellae.

• Adjustments can be done with the special adjusting tool. www.indiandentalacademy.com

04/13/2371

• The adjustment tool has retractable spring loaded plunger that fits the internal aspect of the attachment.

• As the instrument is pressed down onto the attachment lamellae squeezed inwards

• This procedure carried out carefully to avoid the subsequent fracture of the prosthesis.






04/13/2376

THE COMPACT UNIT

• The Compact unit is another mall unit.

• The over all height is 2.85mm but the diameter of retention knob is 2.8mm.

• Divergence upto10 degrees has been permitted between two attachments.

• The female section incorporates 8 lamellae that provides adjustable retention.

• The lamellae are protected by plastic sleeves.



04/13/2378

BATTESTI UNIT:• The male unit is splits and incorporates the adjustment

for the retention.

• The male unit can be removed from the base &can be replaced.

• This allows a comparatively neat female unit and reduce the overall diameter[2.3mm] if the attachment.

• Three types of the designs are made.

• Two allows vertical translation & one is ball &socket attachment.



04/13/2380

THE CONOD UNIT:

• The Conod rigid unit available in three heights,also incorporates split male section.

• This allows the diameter of the attachment to 2.4mm.

• Split male unit require special instrument for the adjustment.m



04/13/2382

BARR &FAH UNITS.They are rigid and require little vertical space.

However it is the unit with rounded male section 2.2mm tall that requires the least space.

They require alignment and positioning procedures similar to other stud attachments.



04/13/2384

CEKA SYSTEM• This system available as rigid and resilient

attachments.

• Both share the common base but different female section.

• The space required for the CEKA system is 1.4mm

PLACEMENT OF THE ATTACHMENT STP BY STEP PROCEDURE:

-the spring pin is removed from the unit special mandrel is attached.

-insert the mandrel into the attachment base.

-align the base on the coping connect with the sticky wax www.indiandentalacademy.com

04/13/2385

• CEKA SYSTEM.

• This system available as rigid and resilient attachments.

• Both share the common base but different female section.

• The space required for the CEKA system is 1.4mm





04/13/2389

• Locating instruments are available to place the base of the attachment onto the coping.

• Insert the locating pin into the screw base .

• Investment is placed around the dowel and coping.

• Solder the attachment base &the co[ping.

• After the soldering attachment screw into the base forms the part of the coping.

• Align the attachment base in the coping wax.www.indiandentalacademy.com

04/13/2390

ROTHERMANN UNIT:• The Rothemann unit requires little vertical space.

• It is available as rigid & resilient units.

• The overall height of the unit is 1.1mm &1.7mm for the resilient unit.

• The Rothermann unit is button shaped unit the male has the groove .

• The female section slides over the tapered edge of the male, with free ends of the female engages the deepest retaining groove.

• The female section is designed to retain by the

• acrylic resin.www.indiandentalacademy.com


04/13/2392

• Apart from the little vertical space requirement this is particularly useful in tilted teeth.

• Like most other stud attachment, adequate bulk of the acrylic is essential around the attachment.


04/13/2393

GERBER UNITS

• Available as 2 types of units –rigid &resilient.

• Each of these available in two sizes.

• The larger of the resilient unit is 5.2mm &shorter one is 4.4mm.

• The retention of the both types of the Geber is obtained by retaining spring.


04/13/2394

O-SO SYSTEM

• The system comprises of Vitallium male stud incorporating its own dowel.

• No conventional female is required in the denture,instead a rubber ring is incorporated .

• This arrangement results in saving of space &cost.the total space required is 3.2mm.

• There will be excessive wear of the attachment with excessive divergence.

• The hemispherical head of the male unit permits ball &socket rotation &includes a pressure relating groove to simplify the seating of the denture


04/13/2395

CLINICAL STEPS:• The Endodontically treated roots are reduced to gingival

level.

• Use carbide burs(no.700) to prepare pilot hole to depth of about 6mm following center of the root.

• Then the hole is enlarged with round carbide bur.

• After the preparation has made,the zero degree male units are tried ,ensuring that they seat correctly.

• Depend upon the contour of the edentulous ridges the units are selected whether to use parallel attachments angulated attachment.

• During processing a void should be left over each root to allow the male &eventual ring component of the attachment that will be placed later on.www.indiandentalacademy.com

04/13/2396

HOWMEDICA AND INOUE UNITS

• Howmedia has the plastic dowel form with around head known as micro ring system.

• The plastic pattern is incorporated in the wax up of the root face restoration.retention is provided by small ring that engages the depression under the stud.

• Another attachment system employing an ‘o’shaped rubber retaining element is produced by Inoue attachment.

• Four sizes of the plastic patterns are produced &can be incorporated in wax up of the root restoration.


04/13/2397

• A small measuring device to help with planning vertical &Buccolingual space comes with the kit and the unit can be cast in the material of choice.

• Intra-oral location procedure of the rubber ring are normally recommended.


04/13/2398

• The other two new comers to the field has been produced by WHALEDENT &DR.KURER stud attachments.


04/13/2399

INTRA RADICULAR STUD ATTACHMENT:

• ZEST ANCHOR ATTACHMENT:

• The nylon male is incorporated in the denture base & projects downwards,engaging the recess in the root preparation.

• The design reduces the vertical space requirement &imparts the strength of the denture.

• The loads that are applied at a point that is well apical to the gingival margin of the root ,a feature that is impossible to achieve with conventional projecting attachment.www.indiandentalacademy.com




04/13/23103

• Available in two sizes:

• depend upon the root length

• depend upon the diameter .


04/13/23104

• Vertical space requirement are similar to those of Rothermann unit.

• This particular attachment system can be employed for the root preparation without laboratory work.

• STEPS INVOLVING:

• The abutment on the master cast are cut down to 1mm above the gingival margin.

• No.42 drill used to prepare the hole in area corresponding with the center 0.of the root .

• Red spacer plugs inserted into the prepared abutment &denture waxed up round them.


04/13/23105

• This spacer acts as a guide to attachment that will be replaced later on.

• With the spacer the denture is processed and remount on the articulator & check the occlusion.









04/13/23113

The mutual repulsion system has paired bar magnets with like poles adjacent &cured into maxillary &mandibular complete dentures.When magnets were at or near tooth contact the repelling forces exerted a seating effect on both dentures.The disadvantage of this system is the repelling forces rapidly decreases when jaws are widly separated.The constant forces increases the ridge resorption.


04/13/23114

•Mutual attraction of unlike forces:-this system used mainly in sectional dentures, obturators&multi component maxillofacial prosthesis.

•In this system the magnets are placed in denture &underlying soft tissue.

•Continuous attracting forces could cause the embedded bar magnets move through the bone erode the soft tissue &become exfoliated. www.indiandentalacademy.com

04/13/23115

•Magnets used:-the most commonly used magnets are rare earth cobalt(REC); cobalt samarium(Co-Sm).

•They are short magnets,2mm long or even less.

•The magnetic forces they exert is more than 100grms.

•In case of over dentures,the magnets are placed in the roots &impression surface of the over denturewww.indiandentalacademy.com

04/13/23116

•Dislodging forces which exceeds the retention forces unseat the denture.

•The clinical & technical procedures used to insert the magnets are simple.

•There are no path of insertion restriction and thus specialized instruments that are required for precision attachments are not necessary.

•Disadvantages:-the small root face of the supporting roots limit the size of the magnet that can be used,there by limits the retention provided.


04/13/23117

•The magnetic alloy can erode &fracture in the mouth.to eliminate this problem they are coated with silver amalgam or they will be electroplated.

•The thickness of the protective layer also reduces the magnetic effect and there by retention.

•Finally unavoidable magnetic field surrounds both intra radicular &denture magnets. www.indiandentalacademy.com

04/13/23118

•BIOLOGICAL EFFECT OF THE MAGNETS:

•There could be physical effect because of the presence of magnetic field gradient.

•There might be chemical effect because of the alloy it self.

•COPARISION OF THE MAGNGETS & PRECISION ATTACHMENTS :

•Magnets are simple low cost,self adjustable,inherent stress breaking,automatic reseating after denture displacement.

•No special tools are required for the adjustments.www.indiandentalacademy.com

04/13/23119

MAGNETIC RETENTION SYSTEMS:

• 1.CEMENTED IN KEEPER SYSTEM.

• 2.SCREWED IN KEEPER SYSTEM.

• 1.cemented in keeper system:a shallow oval shaped cavity is prepared on the root face of the & a preformed magnetisable disc 5mm long, 3.2mm wide 1.2mm thick cemented into the cavity.

• The root face magnet surface attaches with retentive element.


04/13/23120

• The other face slightly rounded edges which inserted in the root face cavity.

• Two magnetic retention units per denture will provide the adequate retention ,but three or four evenly distributed around the mouth gives better retention &stabilityif more than that patients feel difficult to remove the denture.

• PROCEDURE: Prepare the root face flat &level with gingival margin.

• The root faces are trimmed so,that more or less right angles to the long axis of the root.


04/13/23121

• Enlarge the canal with round bur penetrates the root canal to the depth of about 3mm.

• Select the size of the attachment.

• The root face cavity should be cut to the largest size with out lateral root perforation.

• Check the fit of the system.

• Any cement which is relatively insoluble and abrasion resistant can be used to hold the keeper in the root cavity.

• The keeper is then inserted using handle with light finger pressure is applied until the cement reaches the initial set.


04/13/23122

• SCREWED ON KEEPER SYSTAEM:

• Specially used on root where further root canal treatment may be required (or) reduction in root height may become necessary because of anticipated gingival recession or mucogingival surgery is required.

• The screwed on system is cone shaped counter sunk holes which pass the two self threading pins used to hold it against the root face.

• The system covers 50% more of the root face than does cemented in keeper system.

• This does not require large root face


04/13/23123

• The screwed on system adds 1.2mm to height of the root face.

• The clinical root preparation is same as cemented in keeper system.

• The prefabricated keeper is trail fitted to the root face to verify that close contact between the matting faces has been achieved.

• The keeper is held in the position with the help of the probe .

• The holes are prepared of self threaded pins.

• After the holes has been prepared,self threading pins have been screwed against the root face.




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BAR ATTACHMENTS.

• Bar attachments are those attachments allows the movement between the components.

• Their application in the over dentures construction where 2 or 3 teeth are remain.

• The bar is usually attached to the root filled teeth locking the roots together &improving the crown root ratio.

• The bar joints are subdivide into two groups:

• 1.single sleeve bar joints.

• 2.multiple sleeve bar joints.www.indiandentalacademy.com

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SINGLE SLEEVE BAR JOINTS:

The bar has been produced from wrought wire pear shaped in cross section running between the abutments &just contact with the oral mucosa.

Two sizes of the Dolder bar joints are produced

With heights of 3.5mm &4.5mm.

Sufficient bulk of the acrylic resin must cover the sleeve to prevent the fracture.

The original aim of the DOLDER joint was to allow considerable amount of the vertical & rotational movements & rotation around the long axis.


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• As a single sleeve bar it has to run straight ,it cannot follow the anteroposterior curvature of the ridge.

• Where ever possible the bar should be aligned perpendicularly to the line bisecting the angle between the two lines drawn along the crest of the posterior edentulous ridges.

• Where the arch is markedly curved ,that may occupy tongue space so that, it is better to select another attachment system.

• In marked irregularities of the soft tissue mucosa &mucogingival areas preliminary minor surgery give batter results.


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• Where a large depression is involved the bar can be connected into it with two connecting elements& there by reduces the space occupation.

• Where there are just two teeth & roots on the same side ,such as canine & molar the bar joins two roots& thus run parallel to the edentulous ridges.

• The thickness of the bar is cannot be less than 2mm.




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MULTIPLE SLEEVE SYSTEM:Several short sleeves are substituted .

There is no need to the bar to run straight, it can be bent to follow the vertical contours as well as antero posterior curvature of the ridge.

This simplifies the plaque control.

The sleeves can be placed at convenient location of the denture.

The bars in the circular cross section is the most versatile as it can be bent into all planes.

The rigid bars are available in the oval cross sections.

The tags in the bars resist the rotational movements of the denture. www.indiandentalacademy.com




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IMPRESSION PROCEDURESLocating procedures before denture construction.

locating procedures after denture construction.

Locating procedures before denture construction:

1.all in one procedure.

2.Completing metal work of restoration before overall impression.

3.Transfer coping technique.

Locating procedures after denture construction:

Intra oral &extra oral processing technique.www.indiandentalacademy.com

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All in one impression:• This procedure is particularly useful root

surfaces to be left bare, rather than covering with precious metal coping.

• The recommended material for this technique is Zoë.

• The all in one procedure is not usually suitable for when copings or root preparation to be made as sectioning of cast that is required to produce individual dies


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Completing metal work

• Particularly useful when individual precious metal root copings are to be constructed.

• When attachments are concerned,the method is modified.it is even more important to ensure that pathof insertion of the denture to be clearly marked in the master cast before any metal work is completed.

• The unpolished restorations are placed on their respective roots checked for the accuracy,bbut not cemented.

• The metal restoration are now transferred to the impression


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• The dies are produced &placed on their respective castings and a master cast made on which the denture eventually constructed.


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Transfer coping technique:

• The procedure allows the operator to concentrate in each individual root preparation.

• Impression is placed in copper band is usually employed for the impression technoque with stainless steel dowel or resin pattern to give an accurate impression of the root canal.

• A copper plated die is produced & this die transfer copings are constructed.

• Transfer copings are placed on each of the preparation when operator has determined that they seat accurately.


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• Special tray is used for the impression procedure.

• The dies are placed in the respective places &impression is made.

• The dies are transferred to the impression from which master cast is produced.


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INTRA ORAL PROCESSING• In this procedure the removable section of the

attachment is connected to the over denture in the mouth with self polymerizing resin.

• A vent is placed on the lingual surface of the denture&attachment is placed in proper location.the self polymerizing resin is used to attach the female section in the denture.The excess material will be flown out through the vent.



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Education

Over dentures/ orthodontic straight wire technique