A five-year clinical evaluation of Class II composite resin restorations

Objectives: To study the clinical efficacy of posterior composite resin restorations placed in general practice after five years. Methods: Two commercial composite resin systems were used. Three general practitioners placed the restorations at a Public Dental Health Service Office. The patients were not selected specifically for this study. Class II cavities were restored with Superlux Molar and P-50 APC composite systems on an alternate basis. At baseline, 63 restorations were placed in molars and premolars in 45 patients. For primary caries, generally a conservative cavity design was used (n=23), while replacements of amalgams resulted in the larger conventional Class II design (n=40). The restorations were assessed using a modified USPHS criteria. Wear measurements were determined by the Leinfelder method. Photographs and bite-wing radiographs were taken to supplement the clinical evaluation of colour match, marginal adaptation and recurrent caries. Saliva sampling was performed to determine the rate of secretion and the level of mutans streptococci and lactobacilli. Results: At the five-year review 51 restorations were available for examination, of which nine restorations were rated clinically unacceptable. Including the failed restorations (n=7), at the three-year review, a total of 16 restorations had failed (27.6%) over a five-year period. The most common reasons for failure were recurrent caries (n=7) and marginal defects (n=4). The mean wear of Superlux Molar was 167 μm and of P-50 APC 158 μm. Eight of the 11 patients with failed restorations due to caries and marginal defects had high counts of mutans streptococci at baseline. Conclusions: The failures in the present group of patients did not specifically relate to material, tooth type or cavity design. However, it is suggested that patient factors such as caries activity should be monitored and managed.