Influence of amelogenesis and dentinogenesis imperfecta on dentin bond strength

Teeth with Amelogenesis imperfecta (AI) and Dentinogenesis imperfecta (DGI) normally demand restorative treatment for functional and aesthetic reasons, however scarce information is available concerning the influence of enamel and dentin defects on the adhesive restorative materials bond strength. Objectives: This study evaluated the dentin bond strength and the fracture type characterization of the specimens obtained from teeth affected by AI and DGI type II. Methods: Three groups of third molars (6 DGI type II, 5 AI and 6 sound teeth) were sectioned at the occlusal level until exhibiting a flat superficial dentin, over which, composite resin (Z250, 3M) buildups of 4 mm of thickness were constructed incrementally. After 24 hours storage in distilled water (37°C), the crown was serially sectioned to obtain sticks (1,2mm² cross section) for microtensile bond strength testing. A total of 32 (DGI group), 36 (AI group) and 36 (sound teeth group) sticks were tested. The specimens were attached to a universal testing machine (MTS), using a Bencor Multi-T device. The test was performed at a speed of 0.5 mm/min until the fracture of the specimens. The fracture surface was analyzed by a stereomicroscope at 40x of magnification. One-way ANOVA and c² test were performed to compare, respectively, bond strength and fracture types. Results: DGI type II teeth had lower bond strength mean values (25.366 ± 7.217 MPa), when compared with those observed in AI teeth (42.761 ± 6.375 MPa) and sound teeth (38.376 ± 10.451 MPa). Most of the specimens fractures were of adhesive type (86.54%) for all evaluated dentin tissues. Conclusions: The adhesion to the DGI type II dentin tissue is less resistant, while AI affected and sound teeth present very similar dentin bond strength values.