Marginal Adaptation in vitro and Clinical Outcome of Class-V Restorations

Objective: To evaluate the correlation between the microscopic quantitative margin analysis of two different laboratory test methods (Berlin, Zurich) and the clinical outcome of Class-V restorations. Materials and Methods: Prospective clinical studies of Class-V restorations were searched in the literature with an observation period of at least 18 months and for which also laboratory data were available. The clinical outcome variables were retention loss, marginal discoloration, detectable margins and secondary caries. Forty-four clinical studies matched the inclusion criteria involving 34 adhesive systems (AS). For both laboratory methods and the clinical studies an index has been formulated to better compare the in vitro and in vivo results. Linear mixed models which included a random study-effect have been calculated. As most clinical data were available for 24 months the main analysis had been restricted to this recall interval. Results: The analysis revealed only a weak correlation between clinical and both in vitro indices. The correlation was significant only with the Berlin method but not with the Zurich method and only present if studies were compared, which used the same composite in the in vitro and in vivo study (t-statistics/p-value: Berlin 4.72/p<0.0001; Zurich 2.11/p=0.06). Considering only studies for which the dentin was prepared and/or the enamel was beveled did not improve the correlation. No correlation was found between both in vitro methods.

Conclusion: The microscopic evaluation of the margins of restorations placed in extracted teeth can only partly predict the clinical performance of an adhesive system. An important factor for the prediction of the performance of an adhesive system is that the composite material is identical for both the in vitro and the in vivo study.