关键词: 全冠, 基台, 边缘适合性, 绝对边缘间隙

Abstract: Objective    To study the marginal adaptation of full crowns made of four different materials and provide references for the selection of clinical prosthetic materials. Methods    The study was finished in the Inner Mongolia Key Laboratory of Oral Craniofacial Diseases from January 2022 to April 2022. Using the implant abutment as the preparation，40 cast full crowns made of cobalt chromium and gold alloy were fabricated directly on the abutment by lost-wax casting technique，which were divided into cast cobalt chromium alloy group and cast gold alloy group. Similarly，another 40 full crowns made of zirconia and pure titanium were fabricated by CAD/CAM technique，which were recorded as CAD/CAM zirconia group and CAD/CAM pure titanium group. All crowns were initially tried on the abutment，and the time of grinding the tissue surface of crown to achieve the complete seating was recorded. The absolute marginal discrepancy（AMD）values were measured using the stereomicroscope and macro-measurement software M2-cam. Results    There was a significant difference（F = 91.519，P < 0.001）in the grinding time to achieve the complete seating among groups. Among them，the time of grinding was the longest in the cast cobalt chromium alloy group ［（14.1 ± 2.6）min］ and the shortest in the CAD/CAM zirconia group ［（5.0 ± 1.6）min］，with statistically significant differences（P < 0.05）；the AMD values of each group from small to large were CAD/CAM zirconia group ［（12.19 ± 4.11）μm］，CAD/CAM pure titanium group［（18.46 ± 4.65）μm］，cast gold alloy group［（28.93 ± 4.24）μm］ and cast cobalt chromium alloy group［（42.71 ± 6.94）μm］. The differences were statistically significant（all P < 0.05）. Conclusion    The zirconia crown fabricated by CAD/CAM among the four materials has higher manufacturing accuracy，is easier to grind to achieve complete seating，and has better marginal adaptation.

Key words: full crown, abutment, marginal adaptation, absolute marginal discrepancy