36-Months Clinical Evaluation of Preheated and Room Temperature Resin Composite

Summary The aim of this study was to evaluate the effect of preheating resin composite (RC) on clinical performance of class I restorations in a period of 3-years using a split-mouth double-blinded randomized design.

The description of the experimental design followed the Consolidated Standards of Reporting Trials (CONSORT) statement. The present study was a double-blinded (patients and examiner) randomized clinical trial anticipating the split mouth design. Thirty-five adult patients seeking dental treatment in Operative Department clinic at Faculty of Dentistry, University of Mansoura were enrolled in the current study with a total of 70 Class I restorations. No advertisement was made for participant recruitment, forming a sample of convenience. Each patient much sign a consent form before participating in the current study. The study was conducted from October 2017 to June 2020 as a part of Doctoral dissertation. Mansoura University institution's ethics committee approved the form and protocol before conducting the study. The sample size was calculated based on the clinical success rate (100% retention rate at 3 years) of posterior class I restorations restored with nanofilled composite observed in a previous study.28 According to several parameters including a significance level of 5%, the power of the test was calculated to be 80%, and equivalent limit of 15%. Upon these data, a sample size of 30 subjects was appropriate. Allowing for a 20% drop-out, sample size was set totalizing 35 subjects.

One side of the mouth received preheated composite however in the other side the composite was placed in non-heated state following the manufacturer instructions.

For preheating RC prior to placement, a device called Therma-flo TM RC warming kit (Vista, Wisconsin, USA) was used according to manufacturer's instructions to preheat resin composites

Percentage of marginal staining in patients was clinically assessed using World Dental Federation FDI parameters using a scale from 1 to 5 scores (clinically very good, clinically good, clinically satisfactory, clinically unsatisfactory and clinically poor)

Inclusion Criteria: Patients with primary caries involving occlusal surface only with ICDAS 2 and 3 Patients with cavities no more than one-third of the intercuspal distance Patients must have a good oral hygiene; Patients with tooth gives positive response to testing with an electric pulp tester Patients with normal and full occlusion, Patients with opposing teeth should be natural with no restorations. Exclusion Criteria: High caries risk patients with extremely poor oral hygiene, Patients involved in orthodontic treatment or periodontal surgery, Patients with periodontally involved teeth (chronic periodontitis) Patients with abutments should be excluded. Patients with heavy bruxism habits and clenching