Six-Year Clinical Evaluation of Bulkfill and Nanofill Resin Composite Restorations

Objectives: To compare the performance of a bulkfill and a nanohybrid resin composite restorations in Class II cavities over a period of 6-years.
Methods: Fifty patients having at least two class II carious lesions were recruited in the study. Using a split- mouth design, one lesion in each patient was allocated to be restored using either the Tetric EvoCeram Bulkfill(TBF) or Filtek Ultimate(FU) resin composite with their respective adhesive systems. A total of 104 class II restorations were placed by two operators. During the 6-year follow-up, evaluations were performed by two blinded and calibrated examiners using modified USPHS criteria. Comparison of the groups for each criteria was statistically analyzed using the Chi-square test (p<0.05). Cochran-Q test was used to compare baseline scores with each recall within each group.
Results: Sixty-six restorations (63.46% of the placed restorations) in 33 patients (recall rate: 66%) were evaluated after 6-year. Only one restoration was missing from FU group at 5 years. At the end of 6 years, marginal discoloration was observed in three (9.1%) TBF restorations and eight (36.4%) FU restorations. There was a significant difference between the groups (p<0.05). The FU group showed a significant increase in marginal discoloration at 6 years from the baseline(p<0.05).
Although marginal adaptation was rated as Bravo for 9.1% and 24.2% of TBF and FU restorations, respectively, no significant difference was found between the groups (p>0.05). Significant degradation was observed within each group in terms of marginal adaptation(p<0.05). There were no statistically significant differences between the groups for the other criteria tested(p>0.05). No secondary caries was detected.
Conclusions: With the exception of marginal discoloration, the overall clinical effectiveness of bulkfill and incrementally placed resin composite restorations after 6 years were similar.