Clinical Comparison of Stela Chemically-cured Bulk-fill Composite and Conventional Light-Cured Composite in Posterior Restorations: A 6-Month Clinical Study

Abstract

Background: Composite resins are widely used for posterior restorations, but conventional light-cured composites are associated with polymerization shrinkage and postoperative sensitivity. Stela is a newly developed chemically-cured bulk-fill composite designed to simplify placement and reduce shrinkage stress.

Aim: The purpose of this study was to compare the postoperative sensitivity and short-term clinical performance of new chemically-cured bulk-fill composite with a conventional light-cured composite in posterior restorations.

Materials and methods: A total of 40 Class I restorations in permanent molars were placed in 20 patients (11 females and 9 males, ranging from 18-40 years of age) each patient requiring at least two posterior restorations participated in this split-mouth clinical study. Each patient received one restoration with chemically-cured bulk-fill composite (Stela Automix, SDI, Australia) after the application of Stela primer and another one with a conventional light-cured composite (Filtek P60, 3M ESPE, USA). All restorations were placed by one operator and directly evaluated by two independent examiners. Postoperative sensitivity was recorded on a 10-point visual analogue scale (VAS) after 48 hours, 1 week, 1 month, and 6 months. Clinical performance was assessed by using modified USPHS criteria, which included marginal adaptation, anatomic form, surface texture, and secondary caries. Data were analyzed statistically using paired t-tests and Chi-square tests, with statistical significance set at p < 0.05.

Results: The results at 48 hours and 1 week indicated that Stela Automix restorations showed significantly lower mean VAS scores compared with traditional resin composites restorations (p<0.05). Statistical analysis at 1 and 6 months showed that there was no statistically significant difference between the 2 groups. The results showed that the both groups achieved high clinical ratings for marginal adaptation, anatomic form, and surface texture. Regarding secondary caries, the results showed that the secondary caries were not detected in both groups.

Conclusion: The stela chemically-cured bulk-fill composite demonstrated comparable short-term performance to conventional composites, with reduced early postoperative sensitivity. It may offer practical advantages in everyday restorative dentistry, although longer-term clinical studies are recommended.