Shear bond strength of dentin and deproteinized enamel of amelogenesis imperfecta mouse incisors.

Purpose: The purposes of this study were to: (1) investigate adhesion through shear bond strength (SBS) testing of a resin composite bonded with a self-etching bonding system (SEB) to amelogenesis imperfecta (AI)-affected deproteinized mouse enamel or dentin; and (2) compare wild-type (WT), amelogenin null (AmelxKO), and matrix metalloproteinase-20 null (Mmp20KO) enamel and dentin phenotypes using micro-CT and nanoindentation.
Methods: Enamel incisor surfaces of WT, AmelxKO, and Mmp20KO mice were treated with SEB with and without sodium hypochlorite and tested for SBS. Incisor dentin was also treated with SEB and tested for SBS. These surfaces were further examined by scanning electron miscroscopy. Micro-CT and nanoindentation analyses were performed on mouse dentin and enamel. Data were analyzed for significance by analysis of variance.
Results: Deproteinization did not improve SBS of SEB to these AI-affected enamel surfaces. SBS of AmelxKO teeth was similar in dentin and enamel; however, it was higher in Mmp20KO dentin. The nanohardness of knockout enamel was significantly lower than WT, while knockout dentin nanohardness was not different from WT.
Conclusions: Using animal amelogenesis imperfecta models, enamel sodium hypochlorite deproteinization of hypoplastic and hypoplastic-hypomaturation enamel did not increase shear bond strength, while removal of the defective enamel allowed optimal dentin bonding.