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Denture repair

causes of denture fracture

Construction causesCauses out of the mouth causes in the mouthMaxillary posterior teeth set buccal to the crest of the ridge

2. Unusually thin wax-up

3. Porosity of the denture base

4. Incomplete polymerization of acrylic resin

5. The presence of previous repair1-Excessive pressure exerted by the patient during denture cleaning.

2. Accidental dropping of the Denture

3. Accidental fracture duringdeflaskirg process1-single denture

2-open face denture

3-Lack of adequate relief

4-Poor fit5-Strees concentration

causes in the mouth

a. Single Denture

causes in the mouth

B. Open-face DentureThe open-face denture is a maxillary complete denture with no labial flange but only two labial finger projections extending over the canine eminences. An open-face denture is not as stiff as the conventional flange denture If tins appears to be the primary cause of fracture of the denture base and the anatomy of the pre maxillary denture bearing area prevents the addition of a labial flange, a new denture with a metallic denture base is recommended causes in the mouth

B. Open-face DentureThe open-face denture is a maxillary complete denture with no labial flange but only two labial finger projections extending over the canine eminences. An open-face denture is not as stiff as the conventional flange denture If tins appears to be the primary cause of fracture of the denture base and the anatomy of the pre maxillary denture bearing area prevents the addition of a labial flange, a new denture with a metallic denture base is recommended causes in the mouth

C. Strees Concentration

causes in the mouth

D-lack Of Adequate ReliefInadequate relief of the maxillary denture in the midline of the palate in patients with a small torus palatinus or if the mucosa overlying the crest of the ridge is more compressible than that covering the median raphe of the hard palate, flexing of the denture will occur every time the teeth occlude together resulting in fatigue fracture. causes in the mouth

E. Poor FitResorption of the residual alveolar ridge beneath a maxillary denture following a reasonable period of denture wearing will cause the support to be provided only by the hard palate.

As a result, flexing of the denture will occur when the teeth occlude. If this appears to be the primary cause of fracture, the denture should be rebased after it has been repaired. By this process, the old highly stressed resin is replaced by new and stronger heat- curing resin. causes in the mouth

Causes out of the mouth

Excessive pressure exerted by the patient during denture cleaning

b. Accidental dropping of the denture

c. Accidental fracture during the deflasking processCauses out of the mouth

Constructional Cause

A.Maxillary Posterior Teeth Set Buccal to the Crest of the Ridge:This will cause undue strain upon the midline of the denture. Fatigue of the acrylic resin produced by repealed flexing of the denture will occur by forces too small to fracture it directly.

B-Unusually thin wax-upInadvertently waxing the anterior palatal area of the maxillary denture base too thin.

C-porosity of the denture baseImproper processing procedures resulting in a porous denture base of reduced strength

D- incomplete polymerization of the acrylic resinThis will result if the curing cycle does not include a terminal healing period at 100C.Thus, the strength of the processed denture base will be reduced.

E- The Presence Of A Previous RepairWhen the denture has been repaired previously with autopolymerizing acrylic resin, a further fracture may occur because the auto polymerizing acrylic resin material is more susceptible to fatigue than the heat-cured resin. Furthermore, the original denture base material on either side of the fracture line will already be fatigued.

Fracture Or LossOf Artificial Teeth

TYPES OF DENTURE REPAIRS

1 . Repair of fractured DenturesA. Midline Fracture of the mandibular denture

A. Midline Fracture of the mandibular denture

The most common mandibular denture fracture occurs at or near the midline of the mandibular denture.Repair Procedures1. Assemble the parts of the broken denture accurately in proper relationship and then lute them along the fracture line on the polished, surfaces with sticky wax.2. It is advisable to strengthen the temporarily assembled denture further by the addition of some support across the arch by using orange wood sticks or cotton applicator sticks. If there is doubt regarding the accuracy with which the broken parts can be reassembled, then Ihe repair should not be undertaken.A. Midline Fracture of the mandibular denture

A. Midline Fracture of the mandibular denture

3. Undercut areas on the fitting surface of the denture are identified and blocked out, so that the denture can be removed from the cast except in an area 2 mm on each side of the fracture line. If the entire has an undercut in the region of the repair, place a mix of silicone mold release or alginate irreversible hydrocolloid into the undercut area. This will result in a flexible cast, thus facilitating removal and replacement of the denture after the cast has set, yet maintaining tissue detail or contours necessary for repair.4. The fitting surface of the denture is lightly lubricated with Vaseline and a plaster or stone cast is poured and properly trimmed, When set, carefully remove the cotton applicator sticks and sticky wax5. Remove the broken denture parts from the cast and clean them thoroughlyA. Midline Fracture of the mandibular denture

6. Use a large acrylic bur to cut away from the denture base about 1 mm from either side of the fracture line. Bevel the cut surface outward to increase the bonding surface.7. Prepare dovetails on either side of the fracture line using a suitable fissure bur to strengthen the repair joint. Also, it is advisable to roughen the surface of the old acrylic base to give some form of mechanical interlocking between the new and old acrylic resin material and also to increase to some extent the surface area of the old denture base material available for union with the new acrylic resin.8. Paint the stone cast with a I gin ale separating medium and allow it to dry; otherwise, it will contaminate the resin and severely reduce the repair strength.9. Replace the assembled parts of the denture carefully on the cast.A. Midline Fracture of the mandibular denture

10. Moisten the surface of the old acrylic denture base on either side of the fracture line with acrylic resin monomer to ensure a chemical union between the old and new acrylic resins.

11. Add autopolymerizing acrylic resin monomer and polymer alternately to the repair area until it is slightly overcontoured to allow for possible shrinkage and to pennit some bulk for finishing after polymerization is complete.

12. When the repair area has been built-up sufficiently, adapt tin-foil over the moist acrylic resin, because unless the new acrylic resin is covered during the initial stage of polymerization, an excessive amount of monomer will be lost through vaporization, and as a result the cured acrylic resin may be porous,A. Midline Fracture of the mandibular denture

13. Secure the denture to the cast with a rubber band, and cure it in the pressure chamber at 20 p.s.i, for 30 minutes Processing the denture repair with autopolymerizing acrylic resin in a pressure container will improve the physical properties of the repair.

14. Remove the cured denture from the cast, finish and polish in the usual mannerA. Midline Fracture of the mandibular denture

1 . Repair of fractured DenturesB. Midline fracture of the maxillary denturea. None separated fracture (crack)b. Denture fractured into two or more

a. None separated fracture (crack)

Occasionally, during deflasking procedures the maxillary denture cracks. This usually occurs during the removal of the denture from the master cast by injudicious prying, with the fracture originating at the depth of the labial notch. When this occurs, it can usually be repaired without the necessity of making a new cast as follows:

Gently flex the denture to open the fine crack.However, be careful to avoid complete breakage of the denture.

b. Add a few drops of monomer into the opening, then, apply a small amount of polymer into the crack and allow the denture to return to its normal shape. Excess monomer and polymer are, thus, forced out onto the labial and palatal surfaces from which they are wiped awaya. None separated fracture (crack)

C. Set the denture aside for 30-45 minutes so that polymerization can lake place

d. Finish and polish the denture.

e. Because the crack was almost indiscernible in the first place, the repair will be completely adequate. If loss of a denture substance has occurred or if the crack extended completely through the denture, the previous procedure will not be sufficiently adequate. In this case, a new cast must be made and the repair procedure will then proceed as usuala. None separated fracture (crack)

b. Denture fractured into two or more

The maxillary denture may be repaired with :-A. autopolymerizing acrylic resin:similar to that of the mandibular dentureB. heat-cure acrylic resin:Here, flasking is a must In order to ensure a stronger repair,it is advisable to remove the entire palatal resin:1. to avoid reheating of the old resin with the possibility of warpage or distortion.2. to allow a greater area of old resin to be brought into contact with the new resin material.b. Denture fractured into two or more

I . Assemble the fractured segments and prepare a plaster or stone cast as described previously.

2. Remove the palatal section of the fractured denture; and wax-up a new palatal section and seal it completely to the fractured acrylic segments and to the cast.

3. Flask the denture in the usual manner. However, be certain to embed the acrylic denture completely in the plaster of the first layer, keeping only the waxed-up palatal section exposed.

4. After wax elimination, apply separating medium to the cast and allow it to dry.b. Denture fractured into two or more

5. Paint acrylic resin monomer on the old acrylic and then, pack the heat-cured acrylic resin dough in the mold cavity.

6. Close the flask, and proceed with the processing procedures as for a new denture.

7. Deflask, finish and polish the denture in the usual manner. b. Denture fractured into two or more

Acrylic dentures must be kept in water during the time they are in the laboratory both before and after repair to avoid dimensional changes due to loss of water,When a complete midline fracture occurs after the patient has worm the dentures success fully for a period of time and the patient offers no account of accidental breakage, the denture has probably fractured because it no longer fits the alveolar ridges with the hard midline of the palate serving as a fulcrum. As a result, flexing of the denture will occur when the teeth occlude. Repair is useless in such case because the denture will probably fracture again. Therefore, it is advisable under such circumstances to follow the repair procedure by rebasing the dentureb. Denture fractured into two or more

1 . Repair of fractured DenturesC. Fracture of a denture flangea. Existing flange pieceb. Missing flange piece

Fractured denture flange may occur because of dropping the denture on a hard surface.When these pieces can be accurately oriented they are luted together with sticky wax, then a partial cast is poured and repair is earned out as usual with autopolymerixing acrylic resin.a. Existing flange piece

A fractured denture with a section of the denture base missing will usually require making an impression with the fractured denture in the patients mouth.

1. The fractured denture is inserted into the patients mouth.2. The impression to replace the missing flange is made using either plaster impression or modeling compound refined with zinc oxide-eugenol paste or light body rubber base wash. The impression is made with the mouth closed and the teeth in centric occlusion in order to guard against the flow of the impression material into the fitting surface of the denture.3. A partial cast is poured. When set, the denture is thoroughly cleaned of the impression material.4. Alginate separating medium is painted on the cast and is allowed to dry. The repair is carried out very similar to constructing an acrylic resin baseplate with the sprinkle-on technique.b. Missing flange piece

Denture Repairs Using TRIAD VICMaterial

TRIAD* VLC material is an advanced,visible light cured resin. Normally more than adequate working time is available in ambient room lighting.However, avoid exposure to bright sunlight or bright room lighting to maximize working time. The material contains no methyl methacrylate monomer. It is soft,pliable, and ready to use right from the package. If uncured TRIAD VLC material becomes crusty, forms a skin on its surface and become difficult to blend with the denture resin, it Has been exposed to light for loo long and should be discarded because irreversible partial curing has occurred. Refrigerated storage of the TRIAD VLC material is recommended for maximum shelf life. The material should be allowed to return to room temperature before curingDenture Repairs Using TRIAD VICMaterial

1 . Assemble the broken parts of the denture , and prepare a cast as described previously (coat it with TRIAD Model Release Agent).2. Prepare the fracture area by cutting away from the denture base about either side of the fracture line. Bevel the cut surface outward to increase the bonding surface. Prime roughened surfaces of repair areas with TRIAD VLC Bonding Agent or LUCITONE liquid. If Bonding Agent is used, bench set for two minutes, then processin the TRIAD unit for two minutes.

3. If teeth are being replaced, dean wax from surfaces. Lightly grind areas that were in contact with wax. Paint bonding surfaces of teeth and denture base with TRIAD VLC Bonding Agent. Bench set two minutes, then process in the TRIAD Curing Unit for two minutes.Denture Repairs Using TRIAD VICMaterial

4. Apply TRIAD VLC Denture Base Material to appropriate areas. Coat with TRIAD Air Barrier Coating and process for four minutes. Carefully remove denture from cast. Paint tissue surface with TRIAD Air Barrier Coating and process for eight minutes with tissue side up.

5. Clean with water and brush.

6. Finish and polishDenture Repairs Using TRIAD VICMaterial

2. Replacing a tooth or teetha. Replacement of Loosened Teeth

a. Replacement of Loosened Teeth

When tooth or teeth are loosened and are capable of being replaced . they should be waxed into correct position and a plaster index poured to register their position.

When the plaster index has set, it is separated carefully ,alginate separating medium is applied to it and is left to dry. Then The teeth are removed

dovetails are prepared for the new resin on the lingual or palatal aspect of the teeth to be replaced .This gives adequate access and provides mechanical as well as chemical retention for the new acrylic resin. Usually, the acrylic resin on the labial surface of the denture need not be disturbed. When the preparation is completed, the teeth are repositioned with the aid of the plaster index a. Replacement of Loosened Teeth

The area of the repair is carefully moistened with cold-cure monomer carried to place with a small glass dropper. The polymer is then dusted to place from a small plastic bottle applied from the lingual or palatal side. Alternate applications of monomer and polymer are added until the area is built-up to the desired contour. A slight overcontouring is desirable to compensate for acrylic shrinkage and to give some bulk for finishing.

Place the repaired denture in a pressure pot and cure at 20 p.s.i. for 30 minutes.

Remove the denture, finish and polish in the usual manner

a. Replacement of Loosened Teeth

Fracturing a denture tooth is not an uncommon problem. Porcelain teeth are more prone to breakage, particularly when dropped onto a hard surfaceB. Replacing a Fractured Tooth or Teeth

I . Grind away the fractured tooth carefully with No. 8 round bur without damaging the adjoining teeth.

2. When grinding, make sure to:preserve the labial gingival margin for better esthetic results.create dove-tails lingual to the tooth or teeth to be replaced without perforating the denture base.

3. A tooth of -proper shade and mould is selected. The chosen tooth is tried in position usually some modifications are necessity.B. Replacing a Fractured Tooth or Teeth

4. When the necessary alterations are completed, the selected tooth is set in proper position and is maintained in place by stickcy wax at the mesial and distal incisal angles to hold it to the adjoining teeth.

5. It is advantageous to have both upper and lower dentures when making these repairs because occlusion can be checked during and after the repair. Further refinements are performed in the mouth when the repair is completed.

6. If several teeth are fractured, steps 1 to 3 are carried out. When the teeth position is acceptable, lubricate the surface of the denture base in the concerned area as well as the adjoining teeth on each side with vaseline.

B. Replacing a Fractured Tooth or Teeth

7. Pour a plaster index onto the labial surface of the teeth to be replaced as well as on one or two of the adjoining teeth on each side.

8. When set, separate carefully the plaster index. Apply alginate separating medium to the plaster index and leave it aside to it

9. Remove the teeth to be repaired, thoroughly clean them and the denture base from all traces of wax and vaseline. Reseat the plaster index in position on the denture, then,reposition the teeth to be repaired into it.B. Replacing a Fractured Tooth or Teeth

10. The prepared area of the denture base is moistened with acrylic resin monomer, and autopoiymerizing acrylic resin mix is painted carefully on the lingual prepared area . The resin mix is built-up with slight excess which will be finished to original contour after polymerization.

1 1 . Repair is finished and polished in the usual mannerB. Replacing a Fractured Tooth or Teeth

3. Adding a posterior palatal seal(post-damming)

A denture with an inadequate posterior palatal seal will exhibit generalized lack of retention. The purpose is two-fold; 1 - it accommodates shrinkage of the denture base during processing;2 - it maintains the seal across the posterior border of the denture during function. The time taken before the denture is completed to properly determine the location, extent, and depth of the posterior palatal seal is most important. The dentisl, rather than a dental laboratory technician who has never seen the patient, should scribe the posterior palatal seal into the cast This will prevent the loss of chair side time later on to correct an insufficient posterior palatal seal3. Adding A Posterior Palatal Seal

Laboratory Procedures:Modeling compound or mouth-temperature wax is added to the posterior border of the denture and tested in the mouth until sufficient peripheral seal is apparent.

2. The denture is removed and thoroughly chilled.

3. All undercuts in the tissue surface are blocked out with baseplate wax and a cast is poured. The cast must include all of the posterior palatal seal addition and extend 4 to 6 mm beyond it posteriorly.

4. When the cast has set, it is separated from the denture and the mouth temperature wax or modeling compound is removed.

3. Adding A Posterior Palatal Seal

5. The cast is properly trimmed, and then, provided with escape ways that will lead-off excess acrylic resin material.

6. The cast is painted with alginate separating medium and is allowed to dry,

7. The denture JS cleaned and roughened for application of autopolymerizing acrylic resin.

8. Acrylic resin monomer is applied to moisten the denture surface to receive the new resin.3. Adding A Posterior Palatal Seal

9. A thin soupy mix of autopolymerizing acrylic resin is applied on the denture on the cast , and the denture is seated firmly on the cast. Excess resin will be forced out through the escape ways.

10. The denture and cast are secured with a rubber bands and cured in a pressure pot with warm water at 30 psi. for 1 5 minutes.

11 . The denture is removed, finished and polished in the usual manner3. Adding A Posterior Palatal Seal