Sauro Salvatore, Watson Timothy F, Tay Franklin R, Chersoni Stefano, Breschi Lorenzo, Bernardi Federico, Prati Carlo
Department of Oral Sciences, Alma Mater Studiorum-University of Bologna, Bologna, Italy.
Dent Mater. 2006 Jul;22(7):671-80. doi: 10.1016/j.dental.2005.08.006. Epub 2005 Nov 21.
Dentin adhesives have been proposed as desensitizing agents to seal exposed root dentin surfaces. Simplified 'one-step' dentin adhesives are highly permeable to water. The authors hypothesized that a lactic acid challenge may increase permeability of simplified adhesives and may induce fast degradation of bonding. This phenomenon adversely affects their durability as long term desensitizing agents. The aim of this in vitro study was to evaluate the ability of four dentin adhesives to seal root dentin surfaces that were exposed to water and lactic acid challenges.
Four commercially-available dentin adhesives were applied with a small sponge to the root dentin of extracted human molars as de-sensitizing agents. Impression replicas of the adhesive-covered root dentin were fabricated after water immersion, as a control, and after lactic acid challenge. The replicas were examined with SEM for quantitative comparison of fluid droplet formation on the surfaces. The bonded specimens were also examined using reflected light confocal microscopy.
Replicas of water droplets were observed on the adhesive surfaces, by SEM which corresponded with direct confocal observation of blisters and voids from the surface of the bonded specimens. There were significantly more water droplets from samples that were subjected to lactic acid challenge than water only immersion.
Although the dentin adhesives examined were able to cover exposed root dentin, they all exhibited fluid transudation through the polymerized adhesives. Dentin adhesives were also susceptible to surface degradation after lactic acid challenge. As simplified self-etch adhesives were highly water permeable and exhibited the most extensive surface damage, they may not be the best adhesives to be used for long-term dentin desensitization. These preliminary in vitro findings warrant validation in vivo.
牙本质黏结剂已被提议作为脱敏剂来封闭暴露的牙根牙本质表面。简化的“一步法”牙本质黏结剂对水具有高度渗透性。作者推测乳酸刺激可能会增加简化黏结剂的渗透性，并可能导致黏结快速降解。这种现象会对其作为长期脱敏剂的耐久性产生不利影响。本体外研究的目的是评估四种牙本质黏结剂封闭暴露于水和乳酸刺激下的牙根牙本质表面的能力。
将四种市售牙本质黏结剂用小海绵涂抹于拔除的人磨牙的牙根牙本质上作为脱敏剂。在水浸泡后作为对照，以及在乳酸刺激后，制作覆盖有黏结剂的牙根牙本质的印模复制品。用扫描电子显微镜检查复制品，以定量比较表面上液滴的形成。还使用反射光共聚焦显微镜检查黏结标本。
通过扫描电子显微镜在黏结剂表面观察到水滴复制品，这与从黏结标本表面直接进行共聚焦观察到的水泡和空隙相对应。与仅水浸泡的样品相比，经乳酸刺激的样品产生的水滴明显更多。
尽管所检测的牙本质黏结剂能够覆盖暴露的牙根牙本质，但它们都表现出通过聚合黏结剂的液体渗出。牙本质黏结剂在乳酸刺激后也易受表面降解的影响。由于简化的自酸蚀黏结剂具有高度的水渗透性并表现出最广泛的表面损伤，它们可能不是用于长期牙本质脱敏的最佳黏结剂。这些初步的体外研究结果需要在体内进行验证。
