1994 Volume 13 Issue 6 Pages 586-603
The function of 2-hydroxy-3-(2-naphthoxy)propyl methacrylate(HNPM)in bonding of HNPN/MMA-TBB resins to dentin conditioned with 10-3 was studied.HNPM does not have a reactive group with dentinal components but it has hydrophobic and hydrophilic groups similar to 4-META which facilitates the formation of a hybrid layer by promoting diffusion of monomers into the conditioned substrate.The highest bond strength, 13MPa, was attained with the 3% HNPA/MMA-TBB resin.Creation of the hybrid layer by HNPM/MMA-TBB resins was identified by SEM and TEM.The hybrid layer of 3% HNPM/MMA-TBB resin showed the strongest resistance against degradation with NaOCl.Thickness of the hybrid layer and the resin content were decreased by increasing the concentration above 3% as the rate of polymerization measured with the differential scanning calorimetry(DSC)was increased.TEM examination revealed that encapsulated crystals of hydroxyapatite existed at the bottom of the hybrid layer.It was concluded that a chemical reaction is not essential to create bonding but the hybrid layer formation is the bonding mechanism to dentin.
