Study On The Biocompatibility Of Self-etching Adhesives System Towards Pulp Tissue

Objective The purpose of this study is to compare and evaluate the biocompatibility of three kinds of dentin bonding agents(XenoIII,Adper Prompt,Single bond2) through cell culture in vitro and animal experiment. It could help the practitioners selecting and applying suitable dentin bonding systems correctly in clinic.Methods Normal dental pulp of teenagers were collected and human pulp fibroblast was cultured using tissue explant method. Three kinds of dentin bonding agents(XenoIII,Adper Prompt,Single bond2) were applied on the surface of the dental slices which were 5mm in diameter and 0.5mm in depth. By immersing the slices into the DMEM culture medium, the maceration extracts were obtained. The fifth generation pulp cells were exposed to culture medium containing different concentrations of maceration extracts(100%,50%,25% and 12.5%) for 24h, 72h, and 120h. At last, MTT method was used to evaluate the cytotoxicity of the dentin bonding agents on human pulp fibroblast.Then three ripe,male Beagles were selected and class V cavities were prepared on the cervical part of the teeth's buccal labial surfaces. The cavities were 2mm in diameter and were applied with three different adhesives (XO, AP and SB) then restored with compomer F2000. Indirect pulp capping with Dycal was used as the negative control group and the cavities were restored with Glass ionomer cement. The experimental specimen were fixed and decalcificated at 7 days, 30 days and 90 days. Then the effect of three materials on pulp tissue was evaluated by the pathological section.Results The results showed that three kinds of dentin bonding systems all had cytotoxicity to human pulp fibroblast in different degree in vitro and the cytotoxicity was depended with time and concentration. There was no significant statistical difference between XenoIII and Adaper Prompt(P>0.05). And the cytotoxicity of XoneIII and Adper Prompt was less than Single bond2. The difference was statistically significant (P<0.05).Speaking of animal experiment, pulp reaction among the three dentin bonding agents showed no statistical difference at 7 days(P>0.05). In the 30 days' and 90 days'observation period, pulp tissues of most specimens exhibited normal structure. However, SB group showed more reactive dentin than XO and AP groups, and the difference is statistically significant(P<0.05), which means the irritation of SB to pulp tissue is stronger than others. There was no statistically significant difference between XO and AP groups(P>0.05).Conclusion The results of cell culture in vitro and animal experiment indicated that total-etching adhesives system(SB) has more irritation to pulp than self-etching adhesives system(XO and AP). It suggests that dentists should choose self-etching adhesives system no more than total-etching adhesives system in clinic dentine bonding when the cavity is closing to pulp. At the same time, dentists also should reduce working time, increase setting time, decrease monomer delivery and it's influence to pulp tissue as possible as we can.