Physiological Root Resorption of Deciduous Teeth

乳牙牙根生理性的吸收

林惠美(Hui-Mei Lin)

《臺灣兒童牙醫學雜誌》 4卷3期 (2004/09) Pp. 109-123

https://doi.org/10.6319/TJPD.2004.4(3).2

摘要

乳牙在嬰兒期和年輕孩兒期特別重要。在胎兒時它們就很早開始產生鈣化的現象，而到整顆乳牙完全發育形成時已大約三歲了；但是由乳牙的牙根開始發生吸收到整個乳齒的脫落卻需要長達一個由童年中期到成年早期的時間。然而在完成乳齒齒列的發育後，有四年的時間幾乎沒有其他牙齒更進一步的萌牙出來，雖然在上、下頷骨的骨頭內有正在發育的恆牙以及正在進行牙根吸收的乳牙。而在乳牙繼續地進行牙根的吸收後，其下正在萌牙的永久齒才會位於此乳牙的正下面，所以當它整顆牙齒脫落後，往往只剩乳牙的牙冠和牙根最上面的部分。一般而言，乳牙的脫落乃是它們的根部不斷地進行吸收所產生的結果，但整個過程並非一直持續不停的，在換牙之間會交替地進行修復與休眠。事實上，乳牙的換牙牽涉到硬組織的吸收，牙周組織內膠原纖維的去除，以及相當特殊化的多核破齒細胞來作為媒介。總而官之，乳牙之所以會脫落主要在於它們的根部會發生吸收，而其下正在萌出的永久齒則增進了它在根部進行吸收的工作。

關鍵字

乳齒脫落 ； 繼生恆齒 ； 牙根吸收過程 ； 牙本質噬母細胞

並列摘要

The deciduous teeth are in particular important in the period of infants and young children. They begin to calcify early in the fetal period and complete formation at about three years of age, but the resorption of their roots and exfoliation encompass a time span from middle childhood to early adolescence. Following completion of the eruption of deciduous dentition, there is no further clinical tooth eruption for almost four years, although eruptive and resorptive changes to developing teeth and deciduous tooth roots continue within the bone of the maxilla and mandible. With continuing resorption, the succeeding permanent tooth comes to lie immediately beneath the shedding (resorbing) deciduous tooth. Consequently, when the deciduous tooth is shed, it consists only the crown and the uppermost portion of the root. In general, shedding of the deciduous teeth is due to the progressive resorption of their roots. The resorption process is not continuous; it alternates with periods of rest and repair. In fact, it concerns with hard tissues resorption, the removal of collagen from the periodontal ligament and mediated by highly specialized multinucleated cells referred to as odontoclasts. The exfoliation of the deciduous teeth is mainly brought about by resorption of their roots and enhances by growth and eruption of the succeeding permanent teeth.

並列關鍵字

Shedding of Deciduous Tooth ； Succeeding Permanent Tooth ； Root Resorption Process ； Odontoclasts