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Disturbed tooth eruption in osteopetrotic (op/op) mice: histopathogenesis of tooth malformation and odontomas
Hiroko Ida-Yonemochi1, Tadashi Noda, Hitoyata Shimokawa
1Division of Oral Pathology, Department of Tissue Regeneration and Reconstruction, Niģata University Graduate School of Medical and Dental Sciences, Niģata, Japan.
Background:
Odontoma-like structures are formed in the jaw bone of osteopetrotic (op/op) mice, which have a congenital deficiency in osteoclastic differentiation due to the absence of functional macrophage colony-stimulating factor (M-CSF).
Methods:
To clarify the histopathogenesis of tooth malformation and odontoma-like structures, a 2-year postnatal process of development of the op/op mandibular incisor was examined radiologically and histologically. At the same time, extracellular matrix (ECM) remodeling around tooth germs was analyzed immunohistochemically.
Results:
Abnormal forms of op/op tooth germ were noticeable even at 3 days after birth on a radiogram. Histologically, op/op mice were clearly distinguished by the disappearance of dental follicular space at 3 days. With aging, bone trabeculae, which were not remodeled, penetrated into op/op tooth germs and divided them into several daughter germs, which were recognized as odontomas. In mandibular incisor bodies, the immature ECM components, such as heparan sulfate proteoglycan and tenascin, were preserved diffusely in the dental papilla/pulp, which indicates that maturation of the stroma does not take place in op/op mandibular incisors.
Conclusion:
The observation suggests that the disturbed morphogenesis of op/op tooth germs is functionally explained by the disordered immunolocalization of ECM molecules, and that the dental follicular space is essential for normal tooth development because it prevents bone penetration into the tooth germs.
Insights
Osteopetrotic (op/op) mice develop odontoma-like structures due to impaired tooth germ development. The absence of dental follicular space allows bone to penetrate tooth germs, disrupting normal tooth formation.
Area of Science:
- Developmental biology
- Oral pathology
- Immunohistochemistry
Background:
- Osteopetrotic (op/op) mice exhibit congenital deficiency in osteoclast differentiation due to absent macrophage colony-stimulating factor (M-CSF).
- These mice develop odontoma-like structures in the jaw bone.
Purpose of the Study:
- To elucidate the histopathogenesis of tooth malformation and odontoma-like structures in op/op mice.
- To analyze extracellular matrix (ECM) remodeling during tooth germ development.
Main Methods:
- Longitudinal radiological and histological examination of op/op mouse mandibular incisors over 2 years.
- Immunohistochemical analysis of ECM remodeling around tooth germs.
Main Results:
- Abnormal tooth germ morphology was evident radiologically by 3 days postnatally.
- Disappearance of dental follicular space and bone trabeculae penetration into tooth germs observed.
- Immature ECM components persisted in the dental papilla/pulp, indicating failed stromal maturation.
Conclusions:
- Disordered ECM molecule immunolocalization contributes to disturbed tooth germ morphogenesis in op/op mice.
- The dental follicular space is crucial for normal tooth development by preventing bone invasion.
