Does wisdom tooth provide tooth germs for tooth regeneration?

Introduction Regenerating a tooth completely in human oral cavity is not achieved by current studies yet. Here, we have conceived a man-induced method to construct a teeth germ which might be used to regenerate a tooth in vivo. This idea was generated by traits of the development of the compound odontoma, a benign tumour of tooth malformation. This is a kind of developmental tooth malformation, characterised by several small teeth inside the entity. Those scattered denticles/daughter teeth germs, formed in the early stage of odontoma morphogenesis, show similar layers as in a normal tooth, and could grow into tooth-like shapes. In consideration with recent report that mouse tooth germ constructed in vitro could develop into a fully functioned tooth in adult mouse jaws. We hope this hypothesis helps generate tooth germs for in vivo implantation. Hypothesis Tooth germ of wisdom tooth might be separated into small daughter germs by bone trabecular using tissue-engineering method, to provide more than one tooth germ for tooth regeneration. Evaluation of hypothesis By reconstruction existing dental tissues during tooth organgenesis in the jaw, this hypothesis shows advantage than generating tooth from single stem cell or artificial tooth graft. Conclusion Proving this hypothesis not only facilitates the acquirement of numerous homologous and immunological rejection-free teeth germs to treat tooth loss and deficit, but also helps afford an alternative lesson that merits attention in other human organ regeneration fields. Introduction Tooth regeneration is a promising and challenging project of important part of human organ tissue engineering. It serves to find the best and most potential materials and methods to engineer an artificial whole tooth, and to biologically repair dental caries or cure the inherited or acquired tooth loss and deficiency. During the 20th century, three methods—xenotransplantation, allotransplantation and autotransplantation—have been used not only under investigation but also in the clinics to study the tooth organogenesis and to attempt a better tooth replacement1. Till now, various strategies on engineering teeth have been developed, and they can be sorted into two main streams: one is to recombine and coculture the dislocated epithelium (odontogenic or not) and kinds of mesenchyme cells to form tooth-like tissue. To attempt this, a variety of enriched or purified stem cells, such as dental pulp stem cells, periodontal ligament stem cells, dental follicle stem cells, dental epithelial stem cell, embryonic stem cells, pre-adipose cells and bone marrow stromal cells or even newly established dental cell lines, have been applied2–4. Certain combinations have been proved to successfully generate well-calcified hard tooth tissues, such as enamel-dentin structures, tooth crown, root, periodontium and cementum5,6. Those regenerated hard tissues show similar characteristics to that of a natural tooth. The other approach is to reproduce the developmental process of organogenesis to engineer a tooth germ, in which most cell types that have been used are dental epithelium and mesenchyme. Seeding them into in vitro biodegradable three-dimentions scaffold results in teeth germs and could be transplanted in vivo afterwards. This was achieved eventually in an adult mouse by Takashi Tsuji et al. in 2009, with a fully functional bioengineering tooth model7. Hence, for the time being, the autogenic reconstructed tooth germ seems to be the most potential in the near future. Wisdom tooth is common in most many, but most of them get it extracted due to abnormalities in eruption or difficulty in mastication. By traits of daughter tooth germs development in the compound odontoma, we have hypothesised a method to obtain more tooth germs from one wisdom tooth. The compound odontoma is a subtype of the odontoma, formed in jaw bones, appears as a pile of several small tooth-like masses, and most of it contains normal enamel–dentin arrays and develops as packaged with loosely textured connective tissue with cords and islands of odontogenic epithelium8. In series histopathological sections of immature compound odontomas, pint-sized tooth germs could be usually detected with a low-magnification microscope8. * Corresponding author Email: [email protected] †These authors contributed equally to this work. 1 Department of Oral Maxillofacial-Head Neck Oncology, School and Hospital of Stomatology, Wuhan University, Wuhan 430079, PR China 2 Department of Oral Maxillofacial Traumatic and Plastic Surgery, School and Hospital of Stomatology, Wuhan University, Wuhan 430079, PR China