Ingram G S, Horay C P, Stead W J
Unilever Dental Research, Port Sunlight Laboratory, Bebington, UK.
Caries Res. 1992;26(4):248-53. doi: 10.1159/000261447.
As some currently available toothpastes contain zinc compounds, the reaction of zinc with dental mineral and its effect on crystal growth rates were studied using three synthetic calcium-deficient hydroxyapatites (HAP) as being representative of dental mineral. Zinc was readily acquired by all HAP samples in the absence of added calcium, the amount adsorbed being proportional to the HAP surface area; about 9 mumol Zn/m2 was adsorbed at high zinc concentrations. As zinc was acquired, calcium was released, consistent with 1:1 Ca:Zn exchange. Soluble calcium reduced zinc uptake and similarly, calcium post-treatment released zinc. Pretreatment of HAP with 0.5 mM zinc reduced its subsequent ability to undergo seeded crystal growth, as did extracts of a toothpaste containing 0.5% zinc citrate, even in the presence of saliva. The reverse reaction, i.e. displacement of adsorbed zinc by salivary levels of calcium, however, indicates the mechanism by which zinc can reduce calculus formation in vivo by inhibiting plaque mineralisation without adversely affecting the anti-caries effects of fluoride.
由于目前一些市售牙膏含有锌化合物，因此使用三种合成缺钙羟基磷灰石（HAP）作为牙齿矿物质的代表，研究了锌与牙齿矿物质的反应及其对晶体生长速率的影响。在不添加钙的情况下，所有HAP样品都很容易获取锌，吸附量与HAP表面积成正比；在高锌浓度下，每平方米吸附约9微摩尔锌。随着锌的获取，钙被释放，这与1:1的钙:锌交换一致。可溶性钙减少了锌的吸收，同样，钙后处理释放了锌。用0.5 mM锌预处理HAP会降低其随后进行晶种晶体生长的能力，含0.5%柠檬酸锌的牙膏提取物也是如此，即使在有唾液存在的情况下也是如此。然而，相反的反应，即唾液中的钙取代吸附的锌，表明了锌在体内可以通过抑制牙菌斑矿化来减少牙结石形成而又不会对氟化物的防龋效果产生不利影响的机制。
