Yang Dong-mei, Li Yu-jing, Su Ying, Sun Yi-lin
Department of Pediatric Dentistry, Faculty of Stomatology, Capital University of Medical Sciences, Beijing 100050, China.
Zhonghua Kou Qiang Yi Xue Za Zhi. 2006 May;41(5):275-8.
To evaluate the effect of dentin matrix metalloproteinase (MMP) on the degradation of root dentin collagen.
Root dentin powder was demineralized with acetic acid (pH 4.0) at 4 degrees C for 14 d, then dialysed and centrifuged. Precipitation was divided into 7 groups, with 6 samples in each group, and each sample was 50.0 mg. One milliliter artificial saliva with a different reagent was added in each sample respectively. The reagents were 2 mmol/L APMA (MMP activator), 2 mmol/L EDTA, 100 mmol/L EDTA, 200 mmol/L EDTA, 0.2% and 0.02% chlorhexidine (MMP inhibitor), and the blank artificial saliva was taken as control. The amount of degraded collagen of each sample was determined with hydroxyproline assay kit. Scanning electron microscope was employed to observe the morphological and structural changes of root dentin which was demineralized or put into artificial saliva after being demineralized.
The mean amount of degraded collagen in APMA group was significantly higher than that in the blank group (P < 0.05). The mean amount of degraded collagen in 2 mmol/L, 100 mmol/L, 200 mmol/L EDTA, 0.02% and 0.2% chlorhexidine groups was dramatically lower than that of the APMA group and the blank (P < 0.01). SEM observation indicated that the structural integrity of the collagen network on root surface dentin still existed in root dentin surface after being demineralized alone, while collagenous fibril was destructed and the structural integrity on root dentin surface disappeared after being demineralized and treated by artificial saliva.
MMP in root dentin can degrade root dentin collagen after being activated at low pH followed by neutralization. The results suggest that host MMP may play an important role in the process of dentin caries formation.
评估牙本质基质金属蛋白酶（MMP）对牙根牙本质胶原降解的影响。
牙根牙本质粉末在4℃下用乙酸（pH 4.0）脱矿14天，然后进行透析和离心。沉淀分为7组，每组6个样本，每个样本50.0mg。分别向每个样本中加入1ml含不同试剂的人工唾液。试剂分别为2mmol/L APMA（MMP激活剂）、2mmol/L EDTA、100mmol/L EDTA、200mmol/L EDTA、0.2%和0.02%氯己定（MMP抑制剂），以空白人工唾液作为对照。用羟脯氨酸检测试剂盒测定每个样本中胶原的降解量。采用扫描电子显微镜观察脱矿或脱矿后放入人工唾液中的牙根牙本质的形态和结构变化。
APMA组胶原降解量的平均值显著高于空白组（P<0.05）。2mmol/L、100mmol/L、200mmol/L EDTA、0.02%和0.2%氯己定组胶原降解量的平均值显著低于APMA组和空白组（P<0.01）。扫描电子显微镜观察表明，单独脱矿后的牙根表面牙本质胶原网络结构完整，而脱矿后经人工唾液处理的牙根牙本质表面胶原纤维被破坏，结构完整性消失。
牙根牙本质中的MMP在低pH值激活后经中和可降解牙根牙本质胶原。结果表明，宿主MMP可能在牙本质龋形成过程中起重要作用。
