Longevity of Direct Restorations in Stress-Bearing Posterior Cavities: A Retrospective Study

Abstract

The aims of this retrospective clinical study were to compare the longevities of direct posterior amalgam restorations (AMs) and resin composite restorations (RCs) that were subjected to occlusal stresses and to investigate variables predictive of their outcome. A total of 269 AMs and RCs filled in Class I and II cavities of posterior teeth were evaluated with Kaplan-Meier survival estimator and multivariate Cox proportional hazard model. Seventy-one retreated restorations were reviewed from dental records. The other 198 restorations still in use were evaluated according to modified US Public Health Service (USPHS) criteria by two investigators. The longevity of RCs was significantly lower than that of AMs (AM = 8.7 years and RC = 5.0 years, p<0.05), especially in molars. The prognostic variables, such as age, restorative material, tooth type, operator group, diagnosis, cavity classification, and gender, affected the longevity of the restorations (multivariate Cox regression analysis, p<0.05). However, among the restorations working in oral cavities, their clinical performance evaluated with modified USPHS criteria showed no statistical difference between both restoratives. In contrast to the short longevity of RCs relative to AMs, the clinical performance of RCs working in oral cavities was observed to be not different from that of AMs. This suggests that once a RC starts to fail, it happens in a rapid progression. As posterior esthetic restorations, RCs must be observed carefully with periodic follow-ups for early detection and timely repair of failures.

The effect of clinical performance on the survival estimates of direct restorations

“…In the present study the longer survival time of CR might result from the fact that the material was used in Class V cavity at a higher proportion (Table 2). Like most previous studies, the median survival time of CR (10.9 years) in Class V restorations was not different from that of GI (10.3 years) in the present study 4,12,13,17. Meanwhile, AM restoration had only 8 Class V restorations that were less influenced from the occlusal force than occlusal restorations.…”

Correlation between the beam profile from a curing light and the microhardness of four resins

“…Premature failure of these restorations will have significant health and financial implications. Several recent reports indicate that the median longevity of posterior RBCs placed in dental offices worldwide is close to a mere 6 years [2][3][4]. A recent Cochrane review reported that posterior RBCs are almost twice as likely to fail as amalgam restorations [5].…”

Effect of High Irradiance on Depth of Cure of a Conventional and a Bulk Fill Resin-based Composite

“…2,3 Although some photopolymerizable resin-based composites (RBCs) have been reported to have excellent longterm results in clinical trials, 1,4,5 the results achieved in dental offices worldwide have been less promising. [6][7][8] If the RBC is undercured, the result will be suboptimal properties for the restorative material that could increase the probability of fracture of the restoration, encourage more secondary caries, increase the wear rate, and result in premature failure. 9 Undercuring is especially of concern for Class II restorations that commonly fail due to bulk fracture or secondary caries at the cervicogingival margin.…”