repair of complete dentures/ labial orthodontics

REPAIR OF COMPLETE

DENTURE PROSTHESISINDIAN DENTAL ACADEMY

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WHEN YOU NEED REPAIR?

We need repair of the denture prosthesis, when either of the following conditions are found:

A. Fracture or loss of the denture teeth

B. Fracture of the denture base

C. In adequate posterior seal


A. FRACTURE OR LOSS OF THE DENTURE TEETH

fracturing and chipping of denture tooth is common problem which need repair

Possible causes for fracture of denture tooth

fall of the prosthesis on a hard surface

careless retrieval after processing of the prosthesis

manufacture defect of the denture teeth

porcelain teeth are more prone to fracture than that of acrylic teeth, mainly due to its lower flexural strength. www.indiandentalacademy.comwww.indiandentalacademy.com


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cuspal interference

fracture of porcelain tooth due to uneven contraction of resin base

excessive grinding of a tooth

Lack of bonding between the denture base resin and acrylic tooth causes dislodgement of acrylic tooth from the denture base. This can occur if he wax elimination is not thorough or if tinfoil substitute inadvertently placed on the ridge laps of the teeth is not removed prior to packing


PROCEDURE FOR REPLACEMENT OF ACRYLIC ANTERIOR TEETH:

Remove the fracture tooth by grinding it with a no 8 round bur.

Do not grind the labial gingival margin.

Remove denture base resin from the denture lingual surface adjacent to the tooth to be replaced.

Select a plastic tooth of appropriate size and shape, and custom grind its ridge lap to facilitate correct positioning on the prosthesis.


Check the replacement tooth position from front and above view. Sticky wax may be used to secure its position.

Made an plaster index of labial surfaces of the tooth to be replace and of the adjoining teeth.

Separate the index and remove all traces of sticky wax

With No.6 round bur shallow indentations are placed in the denture tooth ridge lap to provide an additional bonding area

The plaster index and the tooth be replaced are repositioned and autopolymerizing is painted from the lingual or palatal side.


More resin is added and build it up to desired contour.

Polymerization of the repair denture is carried out in a pressure pot of worm water, and cure it at 20psi pressure for 30 minutes.

The prosthesis is removed and polishing of the autopolymerizing resin with flour of pumice using either a rag wheel or a rubber prophy cup.


PORCELAIN ANTERIOR TOOTH REPLACEMENT

The procedure of replacing porcelain denture teeth differ from that of acrylic teeth in the manner of removing the tooth from the denture base.

Procedure:

Heat the end of roach carver or wax spatula in a flame and press it against the fractured porcelain tooth. Several applications may be needed.

Gently pry the porcelain tooth from the denture base and tooth should be separated cleanly.


Replacement tooth of correct mould should be selected with adequate ridge lap. Space is created by removing the denture base from lingual or pin area.Tooth is adjusted in position by trimming and secured in position with sticky wax. A plaster index is made as described for acrylic tooth.


After removing the wax and preparing the tooth, auto polymerizing resin is painted between the ridge lap and denture base taking care not to entrapped air.

Curing of the repair denture is done at 20 psi pressure for 30 minutes.

Polishing of the repaired denture is done with flour of pumice and a rag wheel or a rubber prophy cup.


Replacement of fractured acrylic posterior tooth:

The method of replacing fractured acrylic or porcelain posterior teeth is similar to that for anterior teeth, but the difference is consideration of occlusion when replacing posterior teeth. The denture will need to be remounted for repositioning the replaced tooth in correct occlusion.

Procedure:

Denture prosthesis is mounted on an articulator to facilitate correction of occlusion.


Tooth is removed using No. 8 round bur taking care not to perforate the denture base and preserving the facial gingival margin.

An acrylic resin tooth of correct mould is selected and adjusted by grinding the ridge lap if required.

Proper occlusion is established to the opposing denture tooth and secured in position with sticky wax.

Auto polymerizing resin is painted, curing and polishing is done as previously described for anterior tooth replacement.


Replacement of fractured porcelain posterior tooth :

Denture prosthesis is mounted on an articulator and the fractured tooth is removed as described earlier.

Most of the time the mould No. of denture tooth can be read out through the indentation on the denture base. An impression made in inlay wax of the indentation is helpful.

After selection of the tooth of correct mould, the rest of the procedure is same with that for acrylic tooth.

If the occlusal surface of the fractured tooth is intact, a plaster occlusal index can be made and the mounting of the prosthesis on the articulator can be avoided.


B. FRACTURE OF THE DENTURE BASE

Causes of fracture denture base:

dropped on the hard surface

fracture of ill fitting denture due to:

alveolar ridge resorption

warpage of the denture base

inadequate relief or excessive relief

inaccurate impression

maxillary teeth set outside the ridge

inadequate thickness of the denture base


Type of fracture denture base:

I. Nonseparated fracture

II. Denture fractured into one or more parts

III. Fractured denture with section(s) missing


Repairing of Nonseparated fracture denture base

Procedure:

1.Denture is carefully examined to determine the extent of the fracture by gently flexing, but taking care to prevent breakage.

2. If the fracture denture is self-approximating, a plaster cast is poured extending approximately 10mm to either side of the fracture line

3.If undercut is present in the fracture region, it is block with mix of polyvinyl siloxane to facilitate removing and replacing of the denture on the set cast


The denture is removed from the set cast , and using No. 558 bur the fracture line is ground out from beginning to end creating a bevel outward.

Dovetails are placed in the palate of the maxillary denture to strengthened the repaired joint.

Cast is painted with separating media and once it is thoroughly dried the denture is replaced on the cast.

Auto polymerizing resin is painted on the groove, taking care to avoid air entrapment. Resin is slightly over build up.

Curing, finishing and polishing is done as described earlier.


II. Repair of Denture fractured into one or more parts

Procedure:

All fracture parts of the denture are carefully examined and lute them together with sticky wax and orange wood sticks, taking help of the assistant. Modeling clay can often be used to hold the pieces in contact while the denture being luted together.

A stone cast is poured into the reassembled denture. Undercut is relieved whenever required using mix polyvinyl siloxane.


After the cast has set the denture is removed. Groove and dovetails are made on the pieces as previously described. Wire reinforcement to strengthened the repair can be done if desired.

Separating media is applied on the cast and allowed it to dry thoroughly. The rest of the procedure is carried out as described previously


III. Fractured denture with section(s) missing

fracture denture with a section missing will usually require to make an impression with the denture in place to make a cast, particularly when a broken flange section has been lost.

In addition if the denture is broken into several sections, the denture may require a preliminary repair as previously described prior to making impression of the lost flange.

Auto polymerizing resin is then painted on to the cast to replace the missing portion.


C. INADEQUATE POSTERIOR SEAL

Occasionally it may be necessary to add a posterior palatal seal to a maxillary complete denture prosthesis after it has been processed. Clinically the posterior palatal seal is revaluated for its extension and proper seal. The posterior border of the denture is extended if required and the posterior palatal seal is recorded using modeling compound or fluid wax. The laboratory converts this to auto polymerizing resin as follows:

1. A stone cast is poured that must include all posterior palatal seal addition, extending 4-6 mm beyond it posteriorly.


After the cast has set the denture is removed. The denture may placed in warm water for a few minutes to soften the wax or compound addition prior to removal.

Cast is trimmed off. An anterior finish line is prepared using No.2 round bur. The denture is steam cleaned to remove all traces of wax and compound.

Fitting of the denture is rechecked on the cast.

Separating medium is applied on the cast and allowed it to dry thoroughly.


Auto polymerizing resin is painted on the cast and additional resin is added on the denture surface.

The denture and cast is assembled applying firm finger pressure to remove the excess resin.

Cast and the denture is secure with a rubber band and curing is carried out in a pressure container under 20 psi pressure for 30 minutes.

Finishing and polishing is done as described previously.


Repair of the fractured prosthesis and addition of the posterior palatal seal can also be done using heat cure polymerizing resin. For that additional steps of waxing, fluxing and processing with heat cure polymerizing resin should be carried out.



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repair of complete dentures/ labial orthodontics

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