Pediatric Dentistry Department, Division of Oral Restitution, Track of Medical and Dental Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Biostructrual Science Section, Bio-Matrix Department, Track of Medical and Dental Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
Biomed Res Int. 2018 Apr 16;2018:5658393. doi: 10.1155/2018/5658393. eCollection 2018.
Enamel wear, which is inevitable due to the process of mastication, is a process in which the microcracking of enamel occurs due to the surface contacting very small hard particles. When these particles slide on enamel, a combined process of microcutting and microcracking in the surface and subsurface of the enamel takes place. The aim of this study was to detect microscopic differences in the microcrack behavior by subjecting enamel specimens derived from different age groups (immature open-apex premolars, mature closed-apex premolars, and deciduous molars) to cycles of simulated impact and sliding wear testing under controlled conditions. Our findings indicated that the characteristics of the microcracks, including the length, depth, count, orientation, and relation to microstructures differed among the study groups. The differences between the surface and subsurface microcrack characteristics were most notable in the enamel of deciduous molars followed by immature premolars and mature premolars whereby deciduous enamel suffered numerous, extensive, and branched microcracks. Within the limitations of this study, it was concluded that enamel surface and subsurface microcracks characteristics are dependent on the posteruptive age with deciduous enamel being the least resistant to wear based on the microcrack behavior as compared to permanent enamel.
由于咀嚼过程不可避免，牙釉质磨损是牙釉质表面微裂纹产生的过程，这是由于表面接触非常小的硬颗粒所致。当这些颗粒在牙釉质上滑动时，牙釉质表面和次表面会发生微切削和微裂纹的联合过程。本研究的目的是通过对不同年龄组（未成熟开髓前磨牙、成熟闭髓前磨牙和乳牙）的牙釉质标本进行模拟冲击和滑动磨损试验，在控制条件下检测微裂纹行为的微观差异。我们的研究结果表明，研究组之间的微裂纹特征，包括长度、深度、数量、方向和与微观结构的关系存在差异。乳牙的表面和次表面微裂纹特征之间的差异最为显著，其次是未成熟的前磨牙和成熟的前磨牙，乳牙的牙釉质承受着大量、广泛和分支的微裂纹。在本研究的限制范围内得出结论，牙釉质表面和次表面微裂纹特征取决于萌出后年龄，与恒牙相比，乳牙的抗磨损能力最差，这是基于微裂纹行为得出的。
