Evaluation of the Marginal Adaptability of Indirect Composite and Monolithic Zirconia Crowns - A Stereomicroscopic Analysis

Marginal adaptation plays an important role in the clinical success of any prostheses. Ideal marginal adaptation can produce less gingival irritation and cement dissolution. The presence of marginal discrepancies increases plaque accumulation, secondary caries, pulpal lesions, postoperative sensitivity, periodontal disease and marginal discoloration leading to abutment failure and in turn failure of the prosthesis. A maxillary first molar typhodont tooth was prepared with an aerator handpiece. To make the monolithic zirconia crowns, the prepared tooth was scanned and the STL file was used to design a crown using CAD/CAM software. To fabricate the indirect composite crowns, a clear acrylic mould was created, in which the indirect composite was filled and the tooth was placed. The samples were then placed in a curing unit. The samples were then examined under a stereomicroscope. With the aid of imaging software, marked calibrations were calculated at four marked regions-buccal, distal, lingual and mesial margins. Monolithic zirconia adaptation showed statistically significant results when compared to that of indirect composite crowns (p<0.05). According to the site, results varied with zirconia crowns adapting better in buccal and mesial sites whereas indirect composite crowns adapted better in the distal and lingual sites. Overall, monolithic zirconia adapted statistically significantly better to the prepared typhodont tooth than the indirect composite crowns and should be used as a material of choice for crowns.