A technique for restoring abutments for removable partial dentures

Kenneth

W. Teppo, D.D.S., M.S.,* and Franklin

W. Smith, D.D.S., M.S.**

University of Michigan, kchool of Dentistry, Ann Arbor, Mich.

F

requently it is necessary to restore one or more of the abutment teeth. supporting. a removable partiaf denture when the denture is still giving satisfactory service. The problem may originate from caries, cuspal fracture, or unsatisfactory retentive form of the original abutment. Quite often the partial denture is remade, since its precise relationship to the abutment may be altered by a new crown having significantIy different contours. This article describes a method of making a crown which retains the exact contours of the original abutment. It permits continued use of the removable partial denture without the difhculty and expense of remaking it.

Fig. 1. The defective abutment. Recurrent caries was removed and the cervical defect restored in wax.

TECHNIQUE The defective part of the existing abutment should be restored with soft wax following caries removal and extension of margins onto sound tooth structure. In situations involving fractures the missing cusp should be restored with wax to produce the proper shape and occlusion. The result should represent the exact contours that are desired in the new restoration (Figs. 1 and 2). A rubber base inipression of the dental arch is made in a customized acrylic resin tray. The impression incorporates the contours of the original abutment (Fig. 3). The impression tray should have solid multiple occiusal stops, and all usual impression procedures should be followed. The defective crown is then removed, and the tooth is further altered if necessary to improve the abutment preparation, All undercuts should be filled *A&&ant tics. **Professor dontics.

398

Pmfessor,

Repovable

and Chairman,

OCTOBER1976

Partial

Removable

VOLUME40

Denture Partial

Pmstbodon-

Denture

NUMBER4

Pmstho-

Fig. 2. The removable partial denture is seated en the abutment. The fit is acceptable. with wax and the prepared tooth and adjacent soft tissues lubricated (Fig. 4). All interproximal extensions of the rubber base material except the one adjacent to the abutment tooth should be removed to facilitate the reseating of

~2~-3913/7%/1~39%

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0 197% The C. V. ,&&by

Co.

TECHNIQUE

FOR RESTORING

ABUTMENTS

Fig. 3. The rubber base impression prior to removing the original crown.

Fig. 4. The original crown tooth preparation completed.

of the dental arch

has been removed

and the

the impression. The rubber base impression of the original crown is then carefully filled with a creamy mix of cold-curing resin,* with care being taken to confine the resin to the imprint of this single tooth only. The tray is then reseated firmly in the mouth (Fig. 5). While the tray must seat solidly onto the occlusal stops to assure the proper vertical dimension of occlusion, overseating is prevented by the multiple occlusal contacts. The acrylic resin will fill up the space in the impression left by the shape of the original crown, and the excess will be forced out around the border of the impression. The impression is held firmly until final set of the resin, which takes approximately 3 minutes (Fig. 6). A small amount of the resin can be placed in the buccal vestibule to serve as an indicator. *Duralay Ill.

inlay

THE JOURNAL

pattern

resin, Reliance

OF PROSTHETIC

Dental

DENTISTRY

Mfg.

Co., Worth,

Fig. 5. Rubber base impression containing resin is seated firmly in the mouth.

Fig. 6. excess.

The acrylic

resin pattern

cold-curing

before removing

the

Fig. 7. The acrylic resin pattern is trimmed and reseated in the mouth. The removable partial denture is seated on the pattern to check accuracy of the fit. Upon removal of the impression the acrylic resin pattern is inspected and the excess is trimmed to the margins. Finish lines and margins can be readily identified if sharply prepared. The margins should

399

TEFFO

Fig. 11.

AND

SMITH

The finished gold crown is seated in the

mouth.

Fig. 9. The cast gold crown and sprue. Fig. ~2. The removablepartial denture is seatedon the new gold crown in the mouth and showsacceptablefit.

Fig. 10. The castgold crown is seatedon the die if the indirect techniqueis used. be smoothed with sandpaper disks to the proper extension. Multiple -options for checking or correcting marginal integrity are available, and different methods might be chosen, depending on accessibility of the specific areas. The pattern should be reseated

400

in the mouth and again checked for accuracy. Small increments of resin can be added, or soft wax* may be painted 1 mm inside the margin before reseating to assurethat an intimate fit exists. It is also possible to obtain another.impression for die construction if an indirect model is desired to recheck marginal accuracy or allow for convenient laboratory finishing. An indirect die technique is helpful if gingival margins are deep. The final pattern should be checked in the mouth. with the partial denture seated upon it to assurethat everything is accurate (Fig. 7). The pattern is removed, invested, and cast to produce the new gold crown (Figs. 8 to 10). Only minimal finishing should be necessary, since contours and occlusion are exactly reproduced and the resin leaves a fairly smooth surface. Only the exterior marginal areas *Green

Casting

Wax,

Kerr

Mfg.

oc'KIBER1978

Co., Romulus,

VOLUME

Mich.

4t~

NUMBEB

4

TECHNIQUE

FOR RESTORING

ABUTMENTS

that were modified will need smoothing. Polishing in this region will not affect the fit of the partial denture (Figs. 11 and 12). A temporary restoration to be used with the removable partial denture can be made using the above technique. SUM~RY A technique was presented to restore a removable partial denture abutment so that the removable

IADR I’ROSTHODONTIC

denture can continue to be used. The technique uses cold-curing acrylic resin in a rubber base impression form. The technique can be adapted to both direct and indirect procedures. Reprint requests to: DR. KENNETH W. TEPPO UNIVERSITY OF MICHEAN SCHOOL OF DENTISTRY ANN ARBOR, MICH. 48104

ABSTRACT

K~~~~~~i~i~ of border movements, Part 1: Computer methuds for standwdized measurements 5. M. Lupkiewin, College of Dentistry,

M. Ariet, J. Fujimato, C. H. Gibbs, H. C. Lundeen and R. E, M&an University

of Florida, Gainesville,

Fla.

Electronic equipment and computer processing of jaw movement signals provide a more precise, reproducible and objective level of measurement over manual techniques. This paper discusses automated techniques to process border jaw movement which have typically been traced with pantographic face bows. Pathways of movements are calculated and plotted for the right and left condyles in protrusive and lateral movements. The Fisner angles are calculated. The Bennett moment is represented graphicafly as weii as numerically in the immediate and Supported by NIDR Grant No. DEO4157. Reptintcd from the Jowwl of Dental Resmrch 57(Special Issue A), 1978 (Abst No. 367) with pmnission of the author and the editor.

THE IOIJRNAL

OF PROSTHETIC

DENTISTRY

progressive sideshifts for the non-working condyles. Movements at the working side condyles are also

measuredand plotted. The re~r~~bi~~~jes of both centric relation and centric occIusion are represented graphically and numerically. Anterior tooth disclusion slopes am calculated and displayed far protrusive right and left excursions. The centric relation to centric occlusion occlusal slide is measured at the condyles and incisors. These techniques are suitable dinical evaluations including: If the se~s~ti~ty to the location of recording points, 2) the importance of intercondylar width, 3) changes in border jaw muvements with time and treatment, and 4) reproducibility of border jaw movements with different jaw manipulation techniques.