Assessment of gingival margin thickness before margin placement

Assessment placement

of gingival

margin

thickness

before

margin

David A. Kaiser, DDS, MSD,* and Thomas W. Hummert, DDSb University of Texas Health ScienceCenter, Dental School, San Antonio, Tex.

T

he cast metal margin has the advantage of better accuracy over the all-porcelain margin. However, there is often a compromise of gingival esthetics by a subgingival

aAssociateProfessorand Interim Chairman,Department of Prosthodontics. bPostgraduatestudent, Department of Prosthodontics. J PROSTHETDENT X994;71:325-6. Copyright @ 1994by The Editorial Council of THE JOURNALOF PROSTHETICDEIWISTRY.

0022-3913/94/$3.00 + 0. 10/4/51904

metal collar on the metal/ceramic crown, which may transmit a gray shade through thin gingival tissue (Fig. 1). There is often a necessity for placement of margins within the gingival sulcus. These indications include subgingival decay, previous restorations, subgingival fracture, root sensitivity, and esthetics. When these situations dictate extension into the intracrevicular space, the dentist needs to decide which type of margin to place. Before preparation and retraction of the gingival tissue, it should be ascertained whether the gingival tissue will allow the shade of the metal to show through the tissue. This

Fig. 1. Left central incisor with metal/ceramic crown. Facial gingival tissue with gray color caused by metal margin.

Fig. 2. Metal matrix bond material placed between facial free gingival margin and tooth. Translucency of gingival tissue can be noted. MARCH 1994

325

THE

JOURNAL

OF PROSTHETIC

RAISER

DENTISTRY

procedure permits the dentist to predetermine whether metal will be seen through the tissue. This procedure allows a diagnostic decision on the type of finish line to prepare and material to use on the facial margin before construction and placement of the final restoration.

PROCEDURE 1. Use a 0.002 inch amalgam matrix band (Teledyne Dental Products, Elkgrove, Ill.) and cut it to form a point. 2. Place the point of the cut matrix band gently under the facial gingival tissue of the tooth to be restored (Fig. 2). 3. Observe the free gingival margin adjacent to the matrix in the gingival sulcis. If the tissue over the metal appears

Bound volumes

available

AND

AUMMERT

gray, consider use of an all-porcelain margin instead of a metal collar.

SUMMARY Matrix material can be cut and placed beneath the gingival tissue to mimic a metal collar on a metal/ceramic crown restoration. If this metal matrix causes a discoloration of the gingival tissue, it would be wise to restore the tooth by using an all-porcelain margin. Reprint requests to: DR. DAVID A. KAISER DEPARTMENT OF PROSTHOD~NTICS UNIVERSITY OF TEXAS I&UTH SCIENCE CENTER SAN AN~NIO, TEXAS 78284

to subscribers

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