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

二胺银氟化物（Saforide）是临床上用于预防龋齿的进展和脱敏过敏牙。不幸的是，由于银沉淀，二胺银氟化物将牙齿染黑。因此，氟化二胺银主要应用于乳牙。为了克服这个缺点，制备了六氟硅酸铵。本研究的目的是评价牛牙经六氟硅酸铵处理后，牙本质小管的封闭能力和抗酸能力。用扫描电子显微镜（SEM）观察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。扫描电镜观察显示，经六氟硅酸铵处理后即刻和7天，开放的牙本质小管完全闭塞。已知一些二氧化硅化合物诱导磷灰石形成，因此，用六氟硅酸铵处理形成的二氧化硅-磷酸钙沉淀物可能通过诱导唾液中的磷灰石沉淀物而对牙本质小管的持久封闭起重要作用。此外，我们还评估了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。氟化二胺银和六氟硅酸铵处理显示出比NaF或酸化磷酸氟化物处理更大的耐酸性。经六氟硅酸铵和氟化二胺银处理后，脱矿深度分别降低了24.1%和23.9%。结果表明，氟硅酸铵能使牙本质小管完全封闭，使牙本质小管中的硅钙磷酸盐沉淀物完全封闭，并能提高牛牙的抗酸能力，对牙本质过敏症的治疗和龋病的预防有一定的作用。

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.