Department of Preventive Dentistry, Academic Centre for Dentistry Amsterdam (ACTA), University of Amsterdam and Free University, Gustav Mahlerlaan 3004, 1081LA Amsterdam, the Netherlands.
J Dent Res. 2012 Dec;91(12):1130-4. doi: 10.1177/0022034512461652. Epub 2012 Sep 24.
Alkali production by oral bacteria in the oral cavity has been linked to protection against dental caries. The current study assessed various parameters associated with ammonium produced during arginine catabolism in dental biofilms. Polymicrobial biofilms were formed with saliva as the inoculum. The NH(3) level and the pH of the spent medium were used to monitor and quantitate the bacterial reactions. The presence of sucrose, a low buffer capacity, and a low pH (≤ pH 4.5) were found to hamper alkali production from arginine. The rate of alkali production exhibited an optimum around pH 5.5. Biofilms were found to produce NH(3) also from polypeptides and proteins in the medium. The biofilm age affected these processes. The experimental model proved valuable for the assessment of the collective bacterial reactions determining the overall pH outcome. This experimental approach could bridge the gap in our knowledge between pH-rise phenomena and caries susceptibility from clinical observations and studies performed on alkali-producing bacteria in well- controlled, though simplified, in vitro models. Analysis of our data supports the hypothesis that the initiation and progression of dental caries may be influenced by the relative rates of acid and base formation, which critically depend on the aforementioned parameters.
口腔中的口腔细菌产生的碱与预防龋齿有关。本研究评估了与牙菌斑中精氨酸分解过程中产生的铵相关的各种参数。使用唾液作为接种物形成多微生物生物膜。使用 NH（3）水平和消耗培养基的 pH 值来监测和定量细菌反应。发现蔗糖的存在、缓冲能力低和 pH 值低（≤pH4.5）会阻碍精氨酸产生碱。碱的产生速率在 pH5.5 左右表现出最佳。生物膜还从培养基中的多肽和蛋白质中产生 NH（3）。生物膜的年龄会影响这些过程。实验模型对于评估确定整体 pH 值结果的集体细菌反应非常有价值。这种实验方法可以弥合我们在 pH 上升现象和从临床观察和在经过良好控制的简化体外模型中对产碱细菌进行的研究中得出的龋齿易感性之间的知识差距。对我们数据的分析支持这样一种假设，即龋齿的发生和发展可能受到酸和碱形成的相对速率的影响，这主要取决于上述参数。
