Application of photoreactive riboflavin in dentin bonding to inhibit matrix metalloproteinase

Abstract

A good bonding between composite resin and dentin is important in restorative dentistry It has been reported that riboflavin (RF) a cross-linker reactive to ultraviolet A (UVA) or blue light (BL) could increase collagen crosslinking and inhibit matrix metalloproteinases (MMP) The purpose of this study was to use RF under BL irradiation to enhance the degree of dentinal collagen crosslinking and inhibit MMP and thus to promote dentin bonding Four experimental groups were 0 1% 1% RF combined with BL 1- and 2- mins irradiation 2% chlorhexidine (CHX) was a control as MMP inhibition First degrees of collagen crosslinking were examined by gel electrophoresis Four collagenases were examined to choose a dentinal MMP mimetic Effect of RF treatment in inhibiting MMP was examined by gelatin zymography The resistance of crosslinked collagen to MMP degradation was tested by gel electrophoresis Additionally dentin was prepared for resin adhesion Bond strengths and stability were checked by a microtensile bond strength (μTBS) test Nanoleakage was observed by scanning electron microscopy (SEM) In situ zymography assay in the dentin specimens was analyzed by confocal microscopy In the gel electrophoresis the pattern of type I collagen showed at γ chain β chain ?1 and ?2 chain The density of γ chain increased in all RF treatment groups while 0 1% RF groups were more effective than 1% RF groups The recombinant human MMP 2 was chosen as a dentinal MMP mimetic due to their similar MMP compositions After RF treatment MMP activity decreased Collagen treated by 0 1% RF showed less enzymatic degradation than 1% RF did In initial stage 0 1% RF groups had the highest bond strength 1% RF CHX and control groups were not significantly different After enzymatic degradation bond strength of all groups decreased 0 1% RF maintained the highest bond strength among groups CHX maintained bond strength Nanoleakage expression of dentin-resin interface was observed near dentin site 0 1% RF groups showed less nanoleakage Under in situ zymography the MMP activity presented at dentin-resin interface According to these findings photoreactive RF increased collagen crosslinking improved adhesion strength and decreased enzymatic degradation 0 1% RF showed better crosslinking and resistance MMP degradation than 1% RF did Application of RF-BL in bonding procedure might be practical and effective to improve collagen crosslinking and enzyme inhibition and thus to enhance bond strength and long-term success rate

Date of Award	2016 Jul 26
Original language	English
Supervisor	Shu-Fen Chuang (Supervisor)