Factors affecting the color stability and staining of esthetic restorations.

This study aimed to assess the color stability of two composite resins, unprotected or protected with a hydrosoluble gel (oxygen inhibitor) during final polymerization, when subjected to different staining solutions and daily tooth brushing simulation. Nanohybrid composite (IPS Empress Direct) or nanofilled composite (Filtek Z350) were used to produce round samples that were either unprotected or protected with a hydrosoluble gel before the final cycle of polymerization. For 5 days, the samples were immersed for 1 h/day in four different staining solutions: distilled water (control), coffee, soft drink, and red wine. Once a day, the samples were also subjected to mechanical brushing with soft-bristled brushes for 30 min. The combination of experimental conditions produced 16 groups (n = 10). Color changes (ΔE) were evaluated at baseline and after mechanical brushing cycles for 1, 3, and 5 days. Data were analyzed by linear regression models. Protection with hydrosoluble gel was able to significantly reduce the color change only on the first day (p = 0.001). The type of composite resin did not significantly affect the color change over the days. Wine affected composite resin color change only on the first day (p = 0.002). Over time, color stability of composite resins did not improve with the protection of a hydrosoluble gel before the final polymerization.

Effectiveness of pre-treatment with chlorhexidine in restoration retention: A 36-month follow-up randomized clinical trial.

OBJECTIVES: This study evaluated the effect of the pre-treatment with 2% chlorhexidine digluconate (CHX) as coadjutant in restoration retention of noncarious cervical lesions (NCCL), after 36 months of follow-up. METHODS: A randomized controlled split-mouth and triple-blind (operators, patients and evaluator) trial was carried out. Patients (n=42) with at least two non-carious cervical lesions were included. The teeth with NCCL were randomly assigned to two treatment groups: application of 2% CHX (experimental group) or a placebo solution (control group) for 60s after acid etching and before the adhesive application. A trained and calibrated examiner evaluated the restorations at baseline (1 week) and at each recall (6, 12, 24 and 36 months) using the FDI criteria. A total of 225 restorations were evaluated after 36-month follow-up. Data were subjected to survival analysis using the Kaplan-Meier method, and the log-rank test was used to evaluate the existence of differences between the survival curves (α=0.05). RESULTS: The restorations survival rate after 36 months of follow-up was 76.1%. There was no difference in the retention and failure rates between the experimental and the control group (p=0.968). There was an increased failure trend when restorations were located subgingival compared to those at the gingival level or supragingival. CONCLUSION: The pre-treatment with 2% chlorhexidine digluconate did not promote further restoration retention of noncarious cervical lesions. CLINICAL SIGNIFICANCE: The cavity pre-treatment with chlorhexidine for inhibition of hybrid layer degradation does not add any beneficial effect to the clinical performance of restorations.