Clinical Evaluation of In-Ceram Crowns

抄録

Purpose: The purpose of this study was to evaluate In-Ceram crowns after 5 years'use in vivo.
Methods: A total of 70 In-Ceram crowns were placed at the Tsurumi University Dental Hospital, Department of Prosthetic Dentistry, during the period from May 1995 to April 1996. A follow-up study was conducted 5 years later, from December 2000 to January 2001. We first examined whether the In-Ceram crowns were still functioning. In cases where the abutment tooth was missing, we asked the patients when and how it was lost. In addition, each crown was evaluated by two examiners according to the modified USPHS (US Public Health Service) criteria, which include marginal integrity, shade compatibility, secondary caries, and wear of the occlusal surface. Then, the examiners calculated the period of functioning of each crown from the date of placement to the present (or the date of failure). The survival curve of the In-Ceram crowns was analyzed using the nonparametric Kaplan-Meier method.
Results: A total of 57 of 70 In-Ceram crowns were examined after a mean of 60 months following their placement, and the remaining 13 were lost to followup. Fifty-two of the 57 In-Ceram crowns were found to be still functional, while the remaining five crowns were missing. Two of the five missing crowns had been removed due to fracture after 33 and 53 months, respectively. Another of the missing crowns had been removed because of periodontal disease after 29 months. The remaining two of the five missing crowns had been removed because of dislodgement of the dowel and core after 39 months in one case, and because a fixed partial denture including this tooth was fabricated after 55 months in the other case. According to the five categories of the modified USPHS (US Public Health Service) criteria, most crowns were assessed as Alpha, while both shade match and wear were rated as Charlie in 3.8% of the crowns. The cumulative survival rate was 91.2% (standard error: 0.038).
Conclusion: Out of the 70 crowns placed in 1995/1996, 57 In-Ceram crowns were available for followup at the end of an average of 5 years after their placement, and the survival rate of the In-Ceram crowns was 91.2%. Within the framework of the limitations of this clinical evaluation, the In-Ceram crowns were found to be clinically acceptable, not only for the anterior teeth, but also the posterior teeth.