Correlation between microleakage and cement thickness in three Class II inlay ceramic systems

Current dental research has focused on the performance of ceramic inlays in Class II restorations. It was already known that cement thickness and microleakage are critical in determining the long-term success of dental restorations. However, no prior work had resolved the relationship between these two factors across different ceramic systems. Standardized inlay preparation and cementation methods are essential for accurate comparisons. The behavior of inlays under mechanical and thermal stress is a key concern in clinical settings. Variability in cement thickness may affect marginal integrity and thus clinical outcomes. Differences in ceramic fabrication methods may influence the final restoration quality. This gap motivated a study to evaluate three ceramic systems for their cement thickness and microleakage. The findings could help clinicians select optimal materials for Class II inlays.

This study aimed to compare cement thickness and microleakage in three ceramic inlay systems. The specific problem addressed was the lack of correlation data between cement thickness and microleakage. The motivation came from the need to understand how different ceramic systems perform in clinical conditions. Mechanical and thermal cycling were used to simulate real-world usage. The goal was to determine if cement thickness affects microleakage in enamel and dentin. The study focused on Class II inlays, which are commonly used in posterior teeth. The researchers wanted to assess the performance of heat-pressed, CAD-CAM, and sintered ceramics. The findings could guide material selection and cementation techniques in dental practice.

The study involved 30 extracted human molars prepared with standardized MOD Class II inlay cavities. Each tooth was randomly assigned to one of three ceramic groups: heat-pressed, CAD-CAM, or sintered. Inlays were fabricated following manufacturer guidelines and cemented with dual-cure resin. Teeth underwent mechanical cycling at 100,000 cycles and 78N force. They also experienced thermocycling with 700 cycles between 5°C and 55°C. After silver nitrate immersion, the inlays were sectioned mesial-distally. Optical microscopy at 40x magnification was used to assess cement thickness and dye penetration. The data were analyzed to compare the three ceramic systems. The study focused on both enamel and dentin margins for microleakage evaluation.

The sintered ceramic system (Colorlogic) had the highest cement thickness in both enamel and dentin. The CAD-CAM (CEREC 2) and heat-pressed (Empress) systems showed lower cement thickness values. In enamel, there was no significant difference in microleakage between the three systems. At the dentin margins, the Colorlogic system had significantly higher dye penetration than the other two. CEREC and Empress showed similar microleakage levels in dentin. Cement thickness values for Colorlogic were 113 ± 25 microm in enamel and 118 ± 23 microm in dentin. CEREC had 78 ± 14 microm in enamel and 87 ± 13 microm in dentin. Empress showed 65 ± 15 microm in enamel and 89 ± 14 microm in dentin. No correlation was found between cement thickness and microleakage in either enamel or dentin.

The study found that the sintered ceramic system (Colorlogic) resulted in the highest cement thickness in both enamel and dentin. Dye penetration at the dentin margin was significantly higher for Colorlogic compared to the other systems. The CAD-CAM and heat-pressed systems showed similar microleakage levels in dentin. No correlation was observed between cement thickness and microleakage in either enamel or dentin. The authors suggest that cement thickness does not directly influence microleakage in this study. The findings indicate that ceramic system type may affect microleakage at the dentin margin. The lack of correlation implies other factors may influence marginal integrity. The results support further investigation into the role of cementation techniques and material properties.