Evaluation of the mechanism of cervical defect formation and development of the effective dentin adhesive system

通过测量树脂复合体的收缩缝隙宽度来评价实验牙本质粘接系统对颈部缺损和完好牙本质洞的粘接效果。20颗有颈部和无颈部缺损的拔除的人牙和20颗完整的拔除的人的牙齿。对10颗颈部缺损牙，用0.5mol/L乙二胺四乙酸二钠(pH 7.4)中和液处理60s，然后冲洗干燥。然后用35vol%的甲基丙烯酸甘油酯溶液填充空洞60秒，然后进行空气喷射。用市售双固化牙本质粘结剂充填树脂复合体，聚合后10min切开标本，在光镜下测量最大收缩间隙宽度。对10例颈部缺损标本，除不做牙本质预备外，其余步骤均采用相同方法。在20颗完整的人牙齿上制备颈腔，并用牙本质粘接系统介导的树脂复合体进行修复，其中牙本质粘结系统有牙本质预充剂和无牙本质预充剂。无论牙本质类型如何，充填后的窝洞都能完全防止缝隙的形成。7例颈部缺损牙标本在不作预充时，均有空洞形成，但均有空洞形成。因此，颈部缺损区的牙本质比完好的牙本质更有利于牙本质粘结，这可能是由于牙本质小管中的碎屑限制了单体的扩散和水的透过。

The efficacy of the experimental dentin bonding system to the cervical defect and the sound dentin cavity was evaluated by measuring the contraction gap width of the resin composite. Twenty extracted human teeth with and without cervical defect and twenty intact extracted human teeth were used. For ten teeth with cervical defect, the defect surface was conditioned with neutralized 0.5 mol/L EDTA (pH 7.4) for 60 sec followed by rinse and dry. Then the cavity was primed with 35 vol % of gtyceryl mono-methacrytate solution for 60 sec followed by air blasting. The resin composite was filled in the cavity after application of the commercial dual-cured dentin bonding agent Ten minutes after the polymerization of the composite, the specimen was sectioned through the canter of the cavity and the maximum contraction gap width was measured on the section of the cavity using the light microscope. For ten specimens with cervical defect, the dentin priming was omitted though other steps were performed in the same methods. The cervical cavity was prepared in the twenty intact human teeth and restored with the resin composite mediated with the experimental dentin bonding system with and without dentin priming. The gap formation was prevented completely in the primed cavity regardless of the kind of the dentin. When the priming was omitted, the complete cavity was observed in the seven specimen of the cervical defect though gap was observed in all of the specimens in the cavity prepared in the intact teeth. Thus it was concluded that the dentin in the cervical defect was more beneficial for dentin bonding than the sound dentin probably because the monomer diffusion and the water through was limited by the debris in the dentin tubules.