增龄对人牙本质失水收缩的重要性

Importance of Aging to the Dehydration Shrinkage of Human Dentin

牙本质内的矿物质随着年龄的增长呈现增长的趋势.由于矿物质与蛋白胶原比例的改变,可能导致牙本质脱水时氢键强度和收缩程度的变化.因此,该研究的目的是确定牙本质收缩随年龄增长的量变.将磨牙牙本质的冠部制成试件,青年组:23≤age≤34,老年组:52≤age≤62,贮存在水或Hanks平衡盐溶液(HBSS)中.利用数字图像相关法(DIC)观察牙本质试件在自由空气状态下的尺寸变化过程.结果表明青年人的牙本质不管在哪个方向或存储时间上,其收缩都明显大于老年人(p<0.01).平行于牙本质小管方向上的应变从牙髓腔侧到釉牙本质界(DEJ)侧依次递增,而垂直于牙本质小管方向的应变则依次递减.即从牙髓腔侧到DEJ牙本质收缩的各向异性增强,该现象在青年人牙本质中尤其明显.

There was an increase in the mineral content of human dentin with aging.Due to the consequent changes in mineral to collagen ratio,this process may influence the degree of hydrogen bonding that occurs with loss of water and the extent of shrinkage as a result of dehydration.Thus,the objective of this investigation was to quantify the differences in dehydration shrinkage of human dentin with patient age.Specimens of coronal dentin were prepared from the molars of young（23≤age≤34） and old（52≤age≤62） patients and then maintained in storage solutions of water or Hanks balanced salt solution（HBSS）.Dimensional changes of the dentin specimens occurring over periods of free convection were evaluated using microscopic digital image correlation（DIC）.Results distinguished that the shrinkage of young dentin is significantly larger than that for old dentin,regardless of orientation and period of storage（p0.01）.Strains parallel to the tubules increased with proximity to the dentin enamel junction（DEJ） whereas the shrinkage strains in the transverse direction were largest in deep dentin（i.e.near the pulp）.The degree of anisotropy in shrinkage increased from the pulp to the DEJ and was largest in young dentin.