Department of Biological Sciences, Bauru School of Dentistry, University of São Paulo, Bauru, Brazil.
Caries Res. 2009;43(6):474-83. doi: 10.1159/000264685. Epub 2009 Dec 10.
The aims of this study were: (1) to correlate surface (SH) and cross-sectional hardness (CSH) with microradiographic parameters of artificial enamel lesions; (2) to compare lesions prepared by different protocols. Fifty bovine enamel specimens were allocated by stratified randomisation according to their initial SH values to five groups and lesions produced by different methods: MC gel (methylcellulose gel/lactic acid, pH 4.6, 14 days); PA gel (polyacrylic acid/lactic acid/hydroxyapatite, pH 4.8, 16 h); MHDP (undersaturated lactate buffer/methyl diphosphonate, pH 5.0, 6 days); buffer (undersaturated acetate buffer/fluoride, pH 5.0, 16 h), and pH cycling (7 days). SH of the lesions (SH(1)) was measured. The specimens were longitudinally sectioned and transverse microradiography (TMR) and CSH measured at 10- to 220-microm depth from the surface. Overall, there was a medium correlation but non-linear and variable relationship between mineral content and radicalCSH. radicalSH(1) was weakly to moderately correlated with surface layer properties, weakly correlated with lesion depth but uncorrelated with integrated mineral loss. MHDP lesions showed the highest subsurface mineral loss, followed by pH cycling, buffer, PA gel and MC gel lesions. The conclusions were: (1) CSH, as an alternative to TMR, does not estimate mineral content very accurately, but gives information about mechanical properties of lesions; (2) SH should not be used to analyse lesions; (3) artificial caries lesions produced by the protocols differ, especially considering the method of analysis.
(1) 分析表面硬度(SH)和横截面硬度(CSH)与人工釉质病损的放射照相参数之间的相关性;(2) 比较不同方案制备的病损。根据初始 SH 值,将 50 个牛牙釉质标本通过分层随机化分配到五个组中,并用不同的方法制备病损:MC 凝胶(甲基纤维素凝胶/乳酸,pH4.6,14 天);PA 凝胶(聚丙烯酸/乳酸/羟基磷灰石,pH4.8,16 小时);MHDP(不饱和乳酸缓冲液/亚甲基二膦酸盐,pH5.0,6 天);缓冲液(不饱和乙酸缓冲液/氟化物,pH5.0,16 小时)和 pH 循环(7 天)。测量病损的 SH(SH(1))。将标本纵向切片,在距表面 10 至 220μm 的深度处进行横向放射照相(TMR)和 CSH 测量。总体而言,矿物质含量与自由基 CSH 之间存在中等相关性,但呈非线性和可变关系。radicalSH(1)与表面层特性呈弱至中度相关,与病损深度呈弱相关,但与整体矿物质损失无关。MHDP 病损的亚表层矿物质损失最高,其次是 pH 循环、缓冲液、PA 凝胶和 MC 凝胶病损。结论是:(1) CSH 作为 TMR 的替代方法,不能非常准确地估计矿物质含量,但能提供关于病损力学性能的信息;(2) 不应该使用 SH 来分析病损;(3) 不同方案制备的人工龋病损不同,特别是考虑到分析方法。