The Effect of including clinical performance on the survival estimates of direct restorations

Abstract

1. objectives In most retrospective studies, the clinical performance of restorations had not been considered in survival analysis. This study investigated the effect of including the clinically unacceptable cases according to modified USPHS criteria into the failed data on the survival analysis of direct restorations as to the longevity and prognostic variables. 2. methods Nine hundred and sixty-seven direct restorations were evaluated. The data of 204 retreated restorations were collected from the records, clinical performance of 763 restorations in function were evaluated according to modified USPHS criteria by two observers. The longevity and prognostic variables of the restorations were compared with or without including clinically unacceptable cases into the failures using Kaplan-Meier survival analysis and Cox proportional hazard model. 3. results The median survival times of amalgam, composite resin and glass ionomer were 11.8 years, 11.0 years and 6.8 years, respectively. Glass ionomer showed significantly low longevity compared to composite resin and amalgam. When clinically unacceptable restorations were included into the failure, the median survival times of them decreased to 8.9 years, 9.7 years and 6.4 years, respectively. After considering the clinical performance, composite resin was the only material that showed a difference. Although the longevity and prognostic variables looked similar in both the survival analyses with and without considering the clinical performance, the longevity of composite resin showed statistical differences and the relative risks in operator groups showed opposite result. In the design of retrospective study, clinical evaluation need to be included.