IADR Abstract Archives
Detecting of the Hybrid Layer Biodegradation Initiation Factor with Scanning Electron Microscope
Objectives: The aim of this study was to evaluate the effect of different monomers on hybrid layer formation and biodegradation, comparison of the current and the possible future methodologies for detection of nanoleakage within the hybrid layer and to elucidate the origin of initiation of hybrid layer biodegradation
Methods: Ninety (N=90) caries-free human third molars were used. Teeth were divided into 3 groups. In the Enamel surface group, lingual or buccal enamel surfaceses were flattened using a high-speed diamond bur under water-cooling. In dentin surface treatment groups the occlusal third of the molars was removed. In the second dentin surface treatment group, teeth were exposed to 10% NaOCl solution for complete removal of exposed collagen matrices. Each group was divided into three subgroups of luting resin materials with etch-and-rinse; self-etch and self-adhesive systems. Resin composite blocks were fabricated and adhered onto the exposed flat dentin and enamel surfaces. The specimens were evaluated with micro shear test at in a universal testing machine. The bond strength values were recorded and statistical analysis were done. After adhesive cementation, teeth were sectioned with a slow-speed saw into multiple beams.
Results: After thermocycle all samples were kept in 50% silver nitrate solution. Samples were analyzed with BSEM for detecting of the hybrid layer biodegradation initiation factor. According to the micro-shear bond tests, higher bond strength values were observed in etch&rinse system. Bond strength values in self-adhesive and etch&rinse groups were significantly higher than self-etch groups in dentin surface treatment and dentin surface treatment groups with NaOCl. Back-scattered scanning electron microscope results showed that, different degradation mechanism was observed.
Conclusions: The present study indicates that, due to the acid etching in dentin, collagen biodegradation was observed due to MMP activity within the hybrid layer. On the enamel surfaces, resin degradation was related with resin monomers in adhesive systems.
Methods: Ninety (N=90) caries-free human third molars were used. Teeth were divided into 3 groups. In the Enamel surface group, lingual or buccal enamel surfaceses were flattened using a high-speed diamond bur under water-cooling. In dentin surface treatment groups the occlusal third of the molars was removed. In the second dentin surface treatment group, teeth were exposed to 10% NaOCl solution for complete removal of exposed collagen matrices. Each group was divided into three subgroups of luting resin materials with etch-and-rinse; self-etch and self-adhesive systems. Resin composite blocks were fabricated and adhered onto the exposed flat dentin and enamel surfaces. The specimens were evaluated with micro shear test at in a universal testing machine. The bond strength values were recorded and statistical analysis were done. After adhesive cementation, teeth were sectioned with a slow-speed saw into multiple beams.
Results: After thermocycle all samples were kept in 50% silver nitrate solution. Samples were analyzed with BSEM for detecting of the hybrid layer biodegradation initiation factor. According to the micro-shear bond tests, higher bond strength values were observed in etch&rinse system. Bond strength values in self-adhesive and etch&rinse groups were significantly higher than self-etch groups in dentin surface treatment and dentin surface treatment groups with NaOCl. Back-scattered scanning electron microscope results showed that, different degradation mechanism was observed.
Conclusions: The present study indicates that, due to the acid etching in dentin, collagen biodegradation was observed due to MMP activity within the hybrid layer. On the enamel surfaces, resin degradation was related with resin monomers in adhesive systems.