This poorly polymerized hydrophilic polymer domain is deteriorated rapidly by environmental water and thus is sensitive to interfacial attack by water. However, in vivo test results are required in further research. Although clinical performance depends on the respective adhesive systems, recent long-term clinical trials of resin composites in non-carious cervical lesions demonstrated good clinical performance DAPT clinical trial [87] and [88]. However, laboratory studies of bond degradation will open the way for the development of new adhesive resin systems that are more stable and have compatible components from the chemical polymer aspect [89], [90] and [91] and morphological nature in the future. Degradation of
the resin composite at the filler–matrix junction (hydrolysis of the silane coupling agent) was
easily observed in teeth that functioned in vivo in monkeys and in humans over 1 year [11] and [12], though the same morphological results are not available for in vitro aging tests such as long-term water storage selleck screening library or thermal cycling. Many studies have reported the enzyme-catalyzed hydrolysis of ester linkage in metharylate-based monomers of resin composite [43], [92], [93] and [94]. It is well known that esterases (i.e. cholesterol esterase, salivary esterases, or porcine liver esterases) induce ester hydrolysis. In contrast to resin or collage hydrolysis, careful comparison between in vivo and in vitro resin composite degradation is needed. In addition, analysis of the degradation of bonding resin by esterases in vitro will be an important research topic in the future. A variety of chemical and physiological factors affect the durability of
resin–dentin Thiamine-diphosphate kinase bonds. This review article concentrates on the morphological evidence of bond degradation. The long-term durability and degradation patterns of resin adhesives have changed with the types of adhesives during the last two decades. There are clear differences among total-etching systems (etch-and-rinse system), self-etching system, and one-bottle self-etching systems. Typical morphological evidence of degradations is provided by collagen hydrolysis of total-etch adhesive systems, resin elution from the hybrid layers of all systems, and hydrolytic degradation at the border between the adhesive/composite junction of one-bottle self-etching adhesives. In addition, the results in many previous studies give promise for the translation of in vitro into in vivo results for bond testing and morphological analysis of resin and collagen hydrolysis. This biodegradation research will provide an avenue of progress for newly developed resin adhesives. This work was supported, in part, by Grants-in-Aid for Scientific Research No. 20592384, and for High-Performance Biomedical Materials Research from the Ministry of Education, Science, Sports and Culture, Japan.