Regeneration of resorbed tooth roots by cementogenesis

病理性牙根吸收常与感染、创伤、肿瘤等并发症有关，也可由某些牙科治疗引起。预防恒牙的病理性吸收是避免牙齿脱落和维持正常口腔功能的关键，但目前尚无有效的治疗方法。Emdogain gelR是一种能促进牙周组织再生的猪釉基质衍生物。由于釉原蛋白被认为是Emdogain中的生物活性物质之一，因此询问釉原蛋白和Emdogain是否对破牙性牙根吸收具有抑制作用是非常有趣的。为了阐明这一点，我们研究了釉原蛋白对体外破牙细胞形成的影响。在此基础上，再植大鼠磨牙，诱导牙根吸收。从人乳牙中分离出破牙本质细胞，在1α25（OH）2维生素D3（Vit. D3）。拔除6周龄雄性大鼠的上第一磨牙，去除牙周韧带后将牙齿放在工作台上1小时。将每颗牙齿再植到牙槽中。在再植之前，用Emdogain凝胶R或与丙二醇藻酸酯混合的Emdogain粉末处理一些牙齿的牙根表面。结果：（1）P172处理组大鼠离体牙培养液中的破牙细胞数量明显减少;（2）再植牙牙根面出现大量的破牙细胞和吸收陷窝。在实验组中，将Emdogain凝胶R或Emdogain粉末涂于牙根上，破牙本质细胞表面、破牙本质细胞数量、牙本质和牙骨质吸收均显著低于未涂的牙根，这些结果表明，釉原蛋白和Emdogain在体外和体内均能抑制牙根吸收。

Pathological tooth root resorption is frequently seen with infection, trauma and tumor, and also induced by some dental treatments. Prevention of pathological resorption in Permanent teeth is a crucial issue to avoid tooth loss and maintain normal oral function, however, there is no effective approach or management for it, so far.Emdogain gelR is a porcine enamel matrix derivative which can promote periodontal tissue regeneration. Since amelogenin is known as one of the bioactive substances in Emdogain, it is quite interesting to ask whether amelogenin and Emdogain have an inhibitory action on odontoclastic root resorption. To clarify this point; we examined the effect of amelogenin on odontoclast formation, in vitro. Furthermore, rat molars were replanted and the root resorption was induced. Emdogain was treated and the effect, on root resorption was examined, in vivo.Odontoclastic cells were isolated from human deciduous teeth and cultured in the presence of 1α25(OH)2vitaminD3 (Vit. D3). The upper first molars off 6 week-old male rats were extracted, and teeth were left on the bench for 1 hr after periodontal ligaments were removed Each tooth was replanted into the socket Root surfaces of some teeth were treated with Emdogain gelR or emdogain powder mixed with the propylene glycol alginate before the replantation. Rats were sacrificed 7 days after replantation and serial saggital sections were prepared.1) P172 treatment significantly decreased odontoclastic Dell number in the culture.2) Numerous root resorption lacunae and odontoclasts were seen on the root surface of replanted teeth. In the experimental group, in which Emdogain gelR or Emdogain powder was applied on roots, values of the odontoclast surface, odontoclast number, and the resorbed dentin and cementum were all significantly lower than those of untreated roots.As conclusion, all these findings suggest that amelogenin and Emdogain inhibit the root resorption, in vitro and in vivo.