EFFECT OF THE FINISH LINE DESIGN UPON THE MARGINAL SEAL OF A COMPLETE CAST CROWN

Introduction: The successful clinical longevity of any indirect dental restoration is dependent upon the precision in its marginal fit. Many factors influence the marginal fit of a complete cast crown like type of cement, cementation pressure, venting, and internal relief of the crown. Aims and objectives: this study was conducted to evaluate the influence of a finish line design of a tooth preparation upon the sealing ability of a complete cast crown. Materials and methods: Thirty complete cast crowns were fabricated from three types of 8mm wide and 6mm high stainless steel dies with 50 angle of convergence differing only in finish line configuration i.e., one with 900 shoulder, other with 900 shoulder with bevel and another with chamfer. Ten crowns from each type of the die were made. A measured volume of autopolymerising resin (Duralay, Reliance, and Mfg.) was poured into castings to make direct Duralay dies. Crowns were cemented upon the Duralay dies and die sectioning was done with diamond discs. The cement space thickness was measured at the middle of the finish line with reflecting microscope. Results: There is statistically significant difference in the seal of the finish line 900shoulder versus 900 shoulder with bevel and 900 shoulder versus chamfer of 0.00001 that is statistically significant at p< 0.05 and 900 shoulder with bevel versus chamfer showed p value of 0.49 that is highly insignificant at p< 0.05. Conclusion: Within the limitations of the study, it can be concluded that finish line design of any preparation affects the sealing ability of the complete cast crown.