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Impact of hypofunctional occlusion on upper and lower molars after cessation of root development in adult mice.
- Source :
-
European journal of orthodontics [Eur J Orthod] 2017 Jun 01; Vol. 39 (3), pp. 243-250. - Publication Year :
- 2017
-
Abstract
- Background: Hypofunctional occlusion is known to lead to changes in the length of roots over time. The mechanisms that drive such changes, however, are poorly understood, with most studies concentrating on juvenile rats prior to the arrest of root development. In this article, we investigated the response of the upper and lower first molar roots to lack of occlusion concentrating on time-points after the development of the roots has ceased using the mouse as a model. Mouse molar roots finish development at weaning, much earlier than rat molars, and display a similar pattern of roots in the lower and upper jaw to humans.<br />Methods: Hypofunctional occlusion was achieved in adult mice at 5 and 9 weeks of age by flattening the cusps of the upper first molar. Mice were then sacrificed after 6 and 2 weeks, respectively, along with control littermates. microCT was used to measure root length, alveolar bone height, and the amount of tooth eruption, followed by sectioning to understand the mechanisms behind the changes at the histological level.<br />Results: In the lower first molar, the response to hypofunctional occlusion was characterized by elongation of both the mesial root and its surrounding alveolar bone, while the distal root was unaffected. In contrast, the response of the upper first molar was characterized by over-eruption of the mesial side of the tooth without any significant change in the alveolar bone or root length. From histologic sections, it was clear that increased deposition of cellular cementum played an important role in the changes that occurred in the lower mesial root.<br />Conclusions: In a mouse model, upper and lower molars responded differently to hypofunctional occlusion, with adult mice showing a different response to that previously reported for juvenile rats, highlighting the importance of considering age and tooth position in cases of hypofunction.<br /> (© The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com)
- Subjects :
- Animals
Dental Cementum physiology
Dental Occlusion
Malocclusion pathology
Maxilla growth & development
Maxilla pathology
Mice
Molar pathology
Tooth Eruption physiology
Tooth Root pathology
X-Ray Microtomography
Malocclusion physiopathology
Molar growth & development
Tooth Root growth & development
Subjects
Details
- Language :
- English
- ISSN :
- 1460-2210
- Volume :
- 39
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- European journal of orthodontics
- Publication Type :
- Academic Journal
- Accession number :
- 27567636
- Full Text :
- https://doi.org/10.1093/ejo/cjw051