Dentine Bond Strength and Remineralization Ability of Sealing Coat Material Containing a New Developed Adhesive Monomer, CMET

Abstract

 Purpose: Dental adhesive materials are widely used for dentinal hypersensitivity treatment. However, there is a problem in the long-term durability of dentin bond strength. Incomplete resin impregnation into the collagen network leaves an exposed zone of demineralized dentin at the base of the hybrid layer. It has been speculated that the exposed collagen fibrils in this region are susceptible to hydrolytic degradation over time, leading to a reduction in bond strength.
 Materials and methods: In this study,“Hybrid coat (HC) ” was used to create an experimental sealing coat material resin composite containing 1.5% calcium salts of 4-methacryloxyethyl trimellitate (CMET). We examined in vitro the mineral induction ability of CMET, compared with that of a model decalcified dentin matrix. We also examined the adhesion ability of HC and CMET to a dentin specimen by means of a micro-tensile bond test.
 Results: In order to analyze the structure of CMET, as a result of performing neutralization titration analysis, CMET presumed that the case where calcium causes the ionic bond to 4-MET within the molecule, and the case where two or more 4-MET (s) cause intermolecular association by the ionic bond by calcium, were intermingled. In the micro-tensile bond test and the fracture modes after bond testing, the sealing coat material containing CMET showed a high adhesive ability when stored in water for 2 years. Moreover, complex viscosity increased with CMET content, and indicated thixotropy. Calcium ions were released from the CMET-HC specimens. More mineralization occurred in the CMET-HC group incubated for 24 hours.
 Discussion: The CMET concentration increased the complex viscosity. As the residual volume of the bonding material to the tooth surface was increased after air blowing, the dentin bond strength was increased. Furthermore, it was suggested by melting CMET in HC that polymerization and a network structure are formed. Moreover, the structure of the bonding layer itself improved. It was considered that short-term bonding strength improved as a result. Dentin mineralization was induced by using the eluate from the hardening object of CMET-HC, and a good result was obtained for the micro-tensile bonding strength two years later. The nanospace formed underneath the bottom hybrid layer by using CMET-HC was blocked by the remineralization substance, inducing long-term durability.
 Conclusion: The CMET combination coat material showed excellent durability of dentin bond strength, and is considered to be effective for dental treatment for dentinal hypersensitivity.