Chameleon teeth develop as individual structures at a distance from the developing jaw bone during the pre-hatching period and also partially during the post-hatching period. However, in the adult, all teeth are fused together and tightly attached to the jaw bone by mineralized attachment tissue to form one functional unit. Tooth to bone as well as tooth to tooth attachments are so firm that if injury to the oral cavity occurs, several neighbouring teeth and pieces of jaw can be broken off. We analysed age-related changes in chameleon acrodont dentition, where ankylosis represents a physiological condition, whereas in mammals, ankylosis only occurs in a pathological context. The changes in hard-tissue morphology and mineral composition leading to this fusion were analysed. For this purpose, the lower jaws of chameleons were investigated using X-ray micro-computed tomography, laser-induced breakdown spectroscopy and microprobe analysis. For a long time, the dental pulp cavity remained connected with neighbouring teeth and also to the underlying bone marrow cavity. Then, a progressive filling of the dental pulp cavity by a mineralized matrix occurred, and a complex network of non-mineralized channels remained. The size of these unmineralized channels progressively decreased until they completely disappeared, and the dental pulp cavity was filled by a mineralized matrix over time. Moreover, the distribution of calcium, phosphorus and magnesium showed distinct patterns in the different regions of the tooth-bone interface, with a significant progression of mineralization in dentin as well as in the supporting bone. In conclusion, tooth-bone fusion in chameleons results from an enhanced production of mineralized tissue during post-hatching development. Uncovering the developmental processes underlying these outcomes and performing comparative studies is necessary to better understand physiological ankylosis; for that purpose, the chameleon can serve as a useful model species.
The mouse third molar (M3) develops postnatally and is thus a unique model for studying the integration of a non-mineralized tooth with mineralized bone. This study assessed the morphogenesis of the mouse M3, related to the alveolar bone, comparing M3 development with that of the first molar (M1), the most common model in odontogenesis. The mandibular M3 was evaluated from initiation to eruption by morphology and by assessing patterns of proliferation, apoptosis, osteoclast distribution, and gene expression. Three-dimensional reconstruction and explant cultures were also used. Initiation of M3 occurred perinatally, as an extension of the second molar (M2) which grew into a region of soft mesenchymal tissue above the M2, still far away from the alveolar bone. The bone-free M3 bud gradually became encapsulated by bone at the cap stage at postnatal day 3. Osteoclasts were first visible at postnatal day 4 when the M3 came into close contact with the bone. The number of osteoclasts increased from postnatal day 8 to postnatal day 12 to form a space for the growing tooth. The M3 had erupted by postnatal day 26. The M3, although smaller than the M1, passed through the same developmental stages over a similar time span but showed differences in initiation and in the timing of bone encapsulation.
- MeSH
- apoptóza fyziologie MeSH
- biologické markery analýza MeSH
- fibroblastový růstový faktor 4 analýza MeSH
- hybridizace in situ MeSH
- izoenzymy analýza MeSH
- kalcifikace zubů fyziologie MeSH
- kyselá fosfatasa analýza MeSH
- mandibula anatomie a histologie růst a vývoj MeSH
- molár třetí anatomie a histologie růst a vývoj MeSH
- moláry anatomie a histologie růst a vývoj MeSH
- morfogeneze fyziologie MeSH
- myši MeSH
- odontogeneze fyziologie MeSH
- orgán skloviny anatomie a histologie růst a vývoj MeSH
- osteoblasty fyziologie MeSH
- osteogeneze fyziologie MeSH
- osteoklasty fyziologie MeSH
- počítačové zpracování obrazu metody MeSH
- processus alveolaris anatomie a histologie růst a vývoj MeSH
- proliferace buněk MeSH
- proliferační antigen buněčného jádra analýza MeSH
- prořezávání zubů fyziologie MeSH
- proteiny hedgehog analýza MeSH
- resorpce kosti patologie patofyziologie MeSH
- techniky tkáňových kultur MeSH
- zobrazování trojrozměrné metody MeSH
- zubní kořen anatomie a histologie růst a vývoj MeSH
- zubní zárodek anatomie a histologie růst a vývoj MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- MeSH
- dentin metabolismus metabolismus MeSH
- kalcifikace zubů účinky léků MeSH
- krysa rodu rattus MeSH
- modely nemocí na zvířatech MeSH
- řezáky MeSH
- tetracyklin škodlivé účinky škodlivé účinky MeSH
- změna barvy zubů chemicky indukované chemicky indukované MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- MeSH
- kalcifikace zubů MeSH
- lidé MeSH
- mikroradiografie MeSH
- zubní kaz patologie MeSH
- zubní sklovina patologie MeSH
- Check Tag
- lidé MeSH
