Objective

The present study evaluated the influence of time, mass and surface area of demineralized dentin collagen matrices on telopeptides release. The hypotheses tested were that the rates of ICTP and CTX release by matrix bound endogenous proteases are 1) not time-dependent, 2) unrelated to specimen mass, 3) unrelated to specimen surface area.

Methods

Non-carious human molars (N = 24) were collected and randomly assigned to three groups. Dentin slabs with three different thicknesses: 0.37 mm, 0.75 mm, and 1.50 mm were completely demineralized and stored in artificial saliva for one week. Collagen degradation was evaluated by sampling storage media for ICTP and CTX telopeptidases. Activity of MMPs in the aging medium was evaluated using fluorometric activity assay kit.

Results

A statistically significant (p < 0.05) decrease in the release of both ICTP and CTX fragments over time was observed irrespective of the specimen thickness. When data were normalized by the specimen mass, no significant differences were observed. Releases of ICTP and CTX were significantly related to the aging time as a function of surface area for the first 12 h. Total MMP activity, mainly related to MMP-2 and -9, decreased with time (p < 0.05).

Significance

Because the release of collagen fragments was influenced by specimen storage time and surface area, it is likely that cleaved collagen fragments closer to the specimen surface diffuse into the incubation medium; those further away from the exposed surface are still entrapped within the demineralized dentin matrix. Bound MMPs can only degrade the substrate within the limited zone of their molecular mobility.

中文翻译：

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从脱矿质牙本质基质释放ICTP和CTX端肽：时间，质量和表面积的影响

客观的

本研究评估了脱矿的牙本质胶原蛋白基质的时间，质量和表面积对端肽释放的影响。测试的假设是基质结合的内源性蛋白酶释放的ICTP和CTX的速率是1）与时间无关，2）与样品质量无关，3）与样品表面积无关。

方法

收集非龋齿的人类臼齿（N = 24）并将其随机分为三组。将三种厚度分别为0.37毫米，0.75毫米和1.50毫米的牙本质板完全脱矿质，并在人造唾液中保存一周。通过采样存储介质的ICTP和CTX端肽酶评估胶原蛋白的降解。使用荧光活性测定试剂盒评估了老化培养基中MMP的活性。

结果

无论样品厚度如何，均观察到ICTP和CTX片段释放随时间的统计学显着降低（p <0.05）。当数据通过样品质量归一化时，没有观察到显着差异。ICTP和CTX的释放与前12小时老化时间随表面积的变化显着相关。总MMP活性（主要与MMP-2和-9有关）随时间降低（p <0.05）。

意义

由于胶原蛋白片段的释放受样品储存时间和表面积的影响，因此更靠近样品表面的裂解胶原蛋白片段可能扩散到培养液中。那些距离裸露表面较远的材料仍被困在脱矿质的牙本质基质中。结合的MMP只能降解其分子迁移率有限区域内的底物。