Comparative Evaluation of Coronal Microleakage in Class-I Cavities Restored with Five Different Direct Composite Resins: An In vitro Confocal Laser Scanning Microscope Study

Abstract Introduction: Microleakage is the passage of bacteria, fluids and ions between a dental filling and the tooth’s cavity walls. It is a key measure of a restorative material’s success and longevity. While composite resins offer better aesthetics and properties than older materials, they can still be limited by factors like polymerisation shrinkage, which contributes to microleakage. This in vitro study aimed to comparatively evaluate coronal microleakage in Class I cavities restored with five different direct composite resins using a Confocal Laser Scanning Microscope (CLSM). Materials and Methods: To compare microleakage among five different composite resins, 100 human premolars with Class I cavities were prepared. After restoration with a specific composite and bonding agent for each of the five groups, all samples underwent thermocycling. They were then submerged in Rhodamine-B dye, sectioned and examined with a CLSM. Statistical analysis using analysis of variance, Tukey and Student’s t -tests determined significant differences. Results: Amongst the five materials, the least microleakage was observed with Tetric N-Ceram, followed by Filtek Z350 XT and Fusion Universal. Brilliant NG exhibited slightly higher microleakage, while the maximum microleakage was recorded with Neo Spectra ST, which was statistically significant with other tested groups. Conclusion: None of the tested composite resins exhibited a complete absence of microleakage. The least microleakage was observed with Tetric N-Ceram, whereas maximum microleakage was recorded with Neo Spectra ST.