36-Month Randomized Clinical Trial Evaluation of Preheated and Room Temperature Resin Composite

Abstract

SUMMARY Objective: This study evaluated the effect of preheating resin composites (RCs) on the clinical performance of class I restorations during a 36-month period using a split-mouth, double-blinded randomized design. Methods and Materials: A total of 35 patients were selected. Every patient received one pair of class I nanofilled resin composite (RC, Filtek Z350 XT) posterior restorations (n=70). One side of the mouth received preheated composites; on the other side, the composite was placed in a nonheated state following the manufacturer’s instructions. These restorations were evaluated at 1-week (baseline), 12-months, 24-months, and 36-months using the FDI World Dental Federation criteria. The statistical analyses were also performed using the Wilcoxon and Friedman tests with the level of significance set at 0.05. Results: After 36 months, 33 patients attended the recall visits, and 66 restorations were evaluated. The Friedman and Wilcoxon signed-rank tests revealed insignificant differences between both groups (p>0.05) for all FDI parameters. However, a significant difference was detected for staining as a criterion at 36 months (p=0.01). Moreover, a significant difference in the staining was detected when the baseline and 36 months were compared in the nonheated RC group (p=0.001). For esthetic, functional, and biological properties, the nonheated composite exhibited 93.9%, 100%, and 100% of the clinically accepted scores, respectively, and the preheated group presented 100% for all properties. Four restorations had postoperative sensitivity at baseline for nonheated (11.4%) and five for preheated (14.2%), but the postoperative sensitivity scores were considered highly acceptable at 12-, 24-, and 36-months. Conclusions: After 36 months, preheated nanofilled RCs showed an acceptable clinical performance similar to that of the nonheated ones in class I restorations, but with better resistance to marginal staining.

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“…This seems to be an advantage when preheating was used, mainly because the increase of the flowability of composite when preheating improves the marginal adaptation of the cavity. These findings align with those by Elkaffas et al [27], who found that the difference between preheating and nonpreheating composite resin restorations performed in posterior restorations were non-significant, even after 36 months of clinical evaluation. However, in the mentioned study, only 3% of the restorations showed marginal defects [27].…”

“…These findings align with those by Elkaffas et al [27], who found that the difference between preheating and nonpreheating composite resin restorations performed in posterior restorations were non-significant, even after 36 months of clinical evaluation. However, in the mentioned study, only 3% of the restorations showed marginal defects [27]. Several methodological differences (including cavity type and composite resin used) between the present study and the previous one help explain these differences.…”

“…Although the preheating of composite resins is not a new technique [15,16] and a wide range of in vitro studies have shown improved properties when preheating composite resins were compared to non-heated composite resins [25], the authors found only a few clinical studies evaluating this technique [26,27].…”

“…Dentists could be reluctant to use preheated composites due to the impression that preheating could be responsible for some damage in the pulp tissue, leading to greater postoperative sensitivity [36]. However, previous clinical studies have not confirmed these expectations [26,27]. In these studies, the authors examined whether preheating a composite resin leads to a change in postoperative sensitivity, mainly in posterior restorations.…”

“…In fact, VisCalor bulk-fill combines a flowable composite's fluidity during application as the material is heated with the sculptability of an encapsulated bulk-fill composite, as it can be placed in increments of up to 4 mm [24]. Despite all these favorable in vitro results for preheated composite resins [25], a closer analysis of clinical studies to evaluate the effects of preheated and non-preheated composite resins produced controversial results [26,27]. However, to the extent of the authors' knowledge, no clinical study has been conducted to compare the clinical performance of this new thermoviscous composite resin to that of non-heated composite resins.…”