Ogawara M, Aoki K, Okiji T, Suda H
Department of Endodontics, Faculty of Dentistry, Tokyo Medical and Dental University, Japan.
Arch Oral Biol. 1997 Oct-Nov;42(10-11):695-704. doi: 10.1016/s0003-9969(97)00068-x.
Ascorbic acid is essential to the biosynthesis of collagen, the major organic matrix component of dentine. The ODS rat is a mutant strain of Wistar rat characterized by hereditary lack of L-gulono-gamma-lactone oxidase and thus is unable to synthesize ascorbic acid. ODS rats were given an ascorbic acid-free diet to investigate how ascorbic acid deficiency affects dentine formation in vivo. Histomorphometric analysis on their growing molars and incisors showed a significant reduction in both size and mineral apposition rate of dentine, as revealed by contact microradiography and fluorescent time-marking, respectively. A similar reduction in bone formation was simultaneously demonstrated in the mandible, confirming the previously reported osteopathic effects of ascorbic acid deficiency. When pulp inflammation was induced in lower first molars by making unsealed pulp exposures, specimens from control animals showed continuous deposition of an osteodentine-like tissue in the radicular pulp chamber; this type of mineralized tissue formation was greatly reduced in ascorbic acid-deprived animals. These results indicate that ascorbic acid deficiency hampers dentine formation under both physiological and pathological conditions of the dentine/pulp complex. ODS rats could be useful in investigating in vivo effects of ascorbic acid deficiency on the formation of dentine and other dental mineralized tissues.
抗坏血酸对于胶原蛋白的生物合成至关重要，而胶原蛋白是牙本质的主要有机基质成分。ODS大鼠是Wistar大鼠的一种突变品系，其特征是遗传性缺乏L-古洛糖酸-γ-内酯氧化酶，因此无法合成抗坏血酸。给予ODS大鼠无抗坏血酸饮食，以研究抗坏血酸缺乏如何在体内影响牙本质形成。对其正在生长的磨牙和切牙进行组织形态计量学分析，结果显示，分别通过接触式显微放射照相术和荧光时间标记法发现，牙本质的大小和矿化沉积率均显著降低。同时在下颌骨中也证实了骨形成有类似的减少，这证实了先前报道的抗坏血酸缺乏的骨病效应。当通过开放牙髓暴露在下颌第一磨牙中诱导牙髓炎症时，对照动物的标本显示在根尖牙髓腔中持续沉积类骨牙本质样组织；在缺乏抗坏血酸的动物中，这种矿化组织的形成大大减少。这些结果表明，在牙本质/牙髓复合体的生理和病理条件下，抗坏血酸缺乏都会阻碍牙本质形成。ODS大鼠可能有助于研究抗坏血酸缺乏对牙本质和其他牙齿矿化组织形成的体内影响。
