Risk factors for caries development on tooth surfaces adjacent to newly placed class II composites--a pragmatic, practice based study.

OBJECTIVES: To assess risk factors for caries development on approximal surfaces in contact with newly placed Class II composite restorations. METHODS: 750 surfaces, either sound or with caries confined to enamel, in contact with newly placed Class II composite restorations, placed by PDS dentists in Norway were evaluated by clinicians, using standardized clinical and radiographic criteria. RESULTS: After the observation period (mean 4.9 year, SD 0.67), 38.8% of the initially sound contact surfaces (n=417) remained sound, 34.0% developed caries confined to enamel and 27.2% developed caries into dentine. Of surfaces with caries confined to enamel present at baseline (n=333), 57.3% remained in enamel, while 42.7% progressed into dentine. Risk factors for dentine caries development were assessed by logistic regression analyses. The risk of developing caries on surfaces that were initially sound at baseline was higher in patients with poor or medium oral hygiene (OR 1.53; CI 1.10-3.68), higher DMFT at baseline (OR 1.12; Cl 1.04-1.20). Maxillary teeth (OR 2.01; Cl 1.14-3.56) and surfaces on the right side of the mouth (OR 1.65; Cl 1.01-2.72) were also risk factors. For surfaces with enamel caries present at baseline, the risk of dentine caries was higher in patients with higher DMFT (OR 1.06; CI 1.00-1.13). In both analyses the treating dentists had a significant impact on the caries development. CONCLUSIONS: Both patient- and dentist related variables are risk factors for caries development on approximal surfaces in contact with newly placed Class II composite restorations. CLINICAL SIGNIFICANCE: All clinicians should be aware of a notable risk of caries development on the adjacent tooth surface, especially when placing approximal restorations in high caries risk patients, and should consider greater use of preventive strategies or non-operative treatment that should be evaluated and repeated at every recall.