Effect of resin coating and occlusal loading on microleakage of Class II computer-aided design/computer-aided manufacturing fabricated ceramic restorations: a confocal microscopic study.

ABSTRACT

OBJECTIVE: To evaluate the effect of resin coating and occlusal loading on microleakage of class II computer-aided design/computer-aided manufacturing (CAD/CAM) ceramic restorations. MATERIAL AND METHODS: Molars were prepared for an mesio-occlusal-distal (MOD) inlay and were divided into two groups non-coated (controls); and resin-coated, in which the cavity was coated with a combination of a dentin bonding system (Clearfil Protect Bond) and a flowable resin composite (Clearfil Majesty Flow). Ceramic inlays were fabricated using the CAD/CAM technique (CEREC 3) and cemented with resin cement (Clearfil Esthetic Cement). After 24 h of water storage, the restored teeth in each group were divided into two subgroups unloaded or loaded with an axial force of 80 N at a rate of 2.5 cycles/s for 250,000 cycles while stored in water. After immersion in 0.25% Rhodamine B solution, the teeth were sectioned bucco-lingually at the mesial and distal boxes. Tandem scanning confocal microscopy (TSM) was used for evaluation of microleakage. The locations of the measurements were assigned to the cavity walls and floor. RESULTS: Loading did not have a significant effect on microleakage in either the resin-coated or non-coated group. Resin coating significantly reduced microleakage regardless of loading. The cavity floor exhibited greater microleakage compared to the cavity wall. TSM observation also revealed that microleakage at the enamel surface was minimal regardless of resin coating. In contrast, non-coated dentin showed extensive leakage, whereas resin-coated dentin showed decreased leakage. CONCLUSIONS: Resin coating with a combination of a dentin-bonding system and a flowable resin composite may be indicated prior to impression-taking when restoring teeth with CAD/CAM ceramic inlays in order to reduce microleakage at the tooth-resin interface.