Comparison of two methods for evaluating the occlusal marginal adaptation of posterior restorations.

Two methods of evaluating the occlusal marginal adaptation of posterior restorations are compared: a direct and an indirect method. The direct method uses modified Ryge criteria and assessments are performed with mirror, probe and operating lamp. With the indirect method assessments are conducted using photographs of impressions of the restorations. For the purpose of the comparison a selected group of newly placed amalgam and composite restorations is used and attention is paid to a 'section method' of observation. This routine of localization the parts of the outline to be measured, permits independent comparison of the assessments. The two methods were applied by pairs of observers and the indirect photographic method appears to be more reliable (percentual agreement between observers 97 percent versus 80-91 percent for the direct method). The agreement between the indirect and direct methods is rather low. The indirect photographic method is more valid when compared to a yardstick, especially if few deficiencies of the margin are expected. It is not clear which method is preferable if more deficiencies occur with restorations of higher age.