Does Preheating Matter? A 36-Month Randomized Controlled Trial of Non-Carious Cervical Lesion Restorations Performed With Preheated and Non-Preheated Composite Resins.

OBJECTIVES

This split-mouth randomized equivalence-controlled trial compared the survival rate, based on material fracture and retention, of a preheated thermo-viscous composite resin (PH) and a non-heated composite resin (NH) for non-carious cervical lesions (NCCLs).

MATERIALS AND

METHODS

Sixty adult participants in good general and oral health, with at least two comparable NCCLs and 20 teeth under occlusion, were eligible for the study. A total of 120 NCCLs were restored, half with VisCalor Bulk, Voco (PH), preheated to 68°C using a bench heater, and half with Admira Fusion, Voco (NH), used at room temperature. A universal adhesive was applied with a selective enamel etching approach before placement of the composite resin. Restorations were evaluated for 36 months according to the FDI World Dental Federation criteria. Survival was analyzed using Kaplan-Meier and equivalence tests, with Hazard ratios (HRs) and 95% confidence intervals (CIs) estimated by Cox models. Secondary FDI outcomes were analyzed using the chi-square test or Fisher's exact test (α = 0.05).

RESULTS

After 36 months, the recall rate was 90%. Ten restorations failed, with five losses in the PH group and five in the NH group (p = 0.95). The material fracture and retention rates, with 95% CIs, were equivalent at 90.7% (83.3-98.8) for both the PH and NH groups (p < 0.001). Cox regression analysis showed no significant difference in failure risk between PH and NH (HR = 0.96; 95% CI: 0.28-3.33). No significant difference was observed in the other secondary outcomes, and all remained clinically acceptable.

CONCLUSION

Preheating makes no difference, since both composite resins showed high and equivalent survival rates above 90% after 36 months of clinical service.

CLINICAL SIGNIFICANCE: Preheating did not provide additional benefits regarding fracture, retention, or other clinical outcomes.