EVALUATION OF THE MARGINAL ACCURACY IN PORCELAIN FUSED TO METAL COPINGS FABRICATED IN TWO DIFFERENT FINISH LINES USING THREE DIFFERENT DIE MATERIALS -A STEREOMICROSCOPIC ANALYSIS AS A COMPARATIVE STUDY

Abstract

Introduction: In the 20th century itself innovative techniques and materials were introduced for the fabrication of restorations that accurately fit over the prepared surface of the tooth. To fabricate these restorations, various materials like metals, alloys, resins, and ceramics were used. Regarding the different materials, metals and alloys have the advantage of superior strength, but for color, it is esthetically not acceptable. Due to a lack of esthetic value metals are replaced by ceramics.
 Objective: To compare the effect of two different marginal geometries shoulder and deep chamfer on metal-ceramic copings fabricated with the use of three different die materials Conventional Type IV Gypsum, epoxy resin, resin-modified Gypsum (Synthetic Gypsum).
 Methods: Two ivorine mandibular first molars were prepared using diamond points for receiving Full veneer porcelain fused to metal restorations. The two designs of circumferential finish evaluated in this study were shoulder and deep chamfer.
 Results: Tests specimen fabricated on 3 groups of die material each having shoulder and deep chamfer finish line were analyzed under a stereomicroscope at four points, following results of vertical marginal gaps in μm were recorded.
 Conclusion: It is thus concluded from the above study that dies fabricated using three different materials in two different finish lines i.e shoulder and deep chamfer did not exhibit a statistically significant difference in terms of marginal accuracy and either of these finish lines can opt for fabrication of metal-ceramic restorations.