Supernumerary teeth in patients with cleft lip and palate: the tooth germs do not separate

ABSTRACT Introduction: Supernumerary teeth in cases of cleft lip and palate do not result from the division of normal germs before the formation of hard tissue. Deciduous and permanent teeth odontogenesis begins after the face has formed, either with or without the cleft. Discussion: The most acceptable hypothesis to enable understanding of the presence of supernumerary teeth on one or both sides of the cleft palate is hyperactivity of the dental lamina in its walls. This hyperactivity, with the formation of more tooth germs, must be attributed to mediators and genes related to tooth formation, under strong influence of local epigenetic factors, whose developmental environment was affected by the presence of the cleft. Conclusion: The current concepts of embryology no longer support the fusion of embryonic processes for the formation of the face, but rather the leveling of the grooves between them. All human teeth have a dual embryonic origin, as they are composed of ectoderm and mesenchyme/ectomesenchyme, but this does not make it easy for them to be duplicated to form supernumerary teeth.

摘要：引言：在唇裂或腭裂病例中，额外牙齿并非由于在硬组织形成之前正常牙胚的分裂所致。乳牙和恒牙的牙胚发育始于面部形成之后，无论是否存在裂隙。讨论：为了理解裂隙腭两侧存在额外牙齿的现象，最可接受的假设是腭壁上成牙板的高度活跃。这种高度活跃，伴随着更多牙胚的形成，必须归因于与牙齿形成相关的介质和基因，在局部表观遗传因素的强烈影响下，其发育环境受到裂隙存在的影响。结论：目前胚胎学的概念不再支持胚胎过程中面部形成的融合，而是支持它们之间沟槽的平展。所有人类牙齿都具有双重的胚胎起源，因为它们由外胚层和中胚层/外中胚层组成，但这并不使它们轻易地被复制以形成额外牙齿。