Development of treatment method for prevention of dental caries and dentin hypersensitivity with silica-fluoride compound

二胺氟化银在临床上用于预防龋齿的发展和对过敏牙齿的脱敏。不幸的是，由于银沉淀，二胺氟化银会使牙齿变黑。因此，二胺氟化银主要应用于乳牙。为了克服这一缺点，制备了六氟硅酸铵。本研究的目的是评价六氟硅酸铵处理后牛牙本质小管的咬合能力和耐酸能力。用扫描电镜观察了六氟硅酸铵处理后即刻和人工唾液浸泡后7天牙本质盘表面的变化。扫描电镜观察发现，六氟硅酸铵处理后和处理后第7天，开放的牙本质小管被完全堵塞。已知某些二氧化硅化合物可诱导磷灰石形成，因此，经六氟硅酸铵处理形成的硅-磷酸钙沉淀物可能通过诱导唾液中的磷灰石沉淀物对牙本质小管的持久闭塞起重要作用。此外，我们还评价了六氟硅酸铵是否能提高牛牙釉质和牙本质的耐酸能力。用表面粗糙度仪测量脱矿牙深度。二胺氟化银和六氟硅酸铵处理的耐酸性能优于NaF或酸化氟化磷酸盐处理。六氟硅酸铵和二胺氟化银处理的脱矿深度分别降低了24.1%和23.9%。综上所述，六氟硅酸铵处理在不改变牙齿颜色的情况下，使开放的牙本质小管与硅-磷酸钙沉淀完全封闭，提高了牛牙的耐酸能力，可用于治疗牙本质过敏和预防龋病的发展。

Diamine silver fluoride (Saforide) is clinical use for prevent of progress of dental caries and desensitizing for hypersensitive tooth. Unfortunately, diamine silver fluoride stained tooth black due to silver precipitation. Therefore, diamine silver fluoride is mainly applied deciduous tooth. To overcome this drawback, ammonium hexafluorosilicate was prepared. The purpose of this study was to evaluate the occluding ability of dentin tubules and acid resistance of bovine tooth after ammonium hexafluorosilicate treatment. The surface of dentin disks was observed with scanning electron microscopy (SEM) at immediately after ammonium hexafluorosilicate treatment and 7 days after immersion in synthetic saliva. SEM observation showed that open dentin tubules were occluded completely immediately after and 7 days after ammonium hexafluorosilicate treatment. Some silica compounds are known to induce apatite formation, therefore, silica-calcium phosphate precipitate formed with ammonium hexafluorosilicate treatment may play important roles for durable occlusion of dentin tubules by inducing apatite precipitate from saliva. In addition, we evaluate whether or not ammonium hexafluorosilicate increase acid resistance of bovine enamel and dentin. The depth of demineralized tooth was measured with surface roughness analyzer. Diamine silver fluoride and ammonium hexafluorosilicate treatment showed greater acid resistance that of NaF or acidulated phosphate fluoride treatment. The deminaralized depth was reduced 24.1% and 23.9%, ammonium hexafluorosilicate and diamine silver fluoride treatment, respectively. It was concluded that ammonium hexafluorosilicate is useful for the treatment of dentin hypersensitivity and prevent of progress of dental caries since ammonium hexafluorosilicate treatment occluded open dentin tubules completely with silica-calcium phosphate precipitate and increased acid resistance of bovine tooth without changing the color of tooth.