AbstractThe roots of our teeth are important for anchoring the teeth in the jaw. Although much is known about crown formation much less if known about how roots develop and how they respond to force during their lifetime. In this thesis the development of roots has been assessed, with particular focus on how occlusion and force impact the roots after eruption. After eruption, teeth are exposed to different degrees of force throughout their history. For example, high force can be generated by mastication, particularly involving a hard diet, while very low force can be generated in the case of hypofunctional occlusion, where the upper and lower teeth fail to come into physical contact. Such hypofunctional occlusion is often induced during orthodontic treatment. The effect of force on roots, particularly in the adult, is not well understood.
To address these gaps in our knowledge we have used mouse models to investigate the effect on roots of changing the forces acting on teeth by altering occlusion or diet. Our results highlight that changes to the forces acting on teeth influence the shape, dimension, and composition of roots through deposition of cellular cementum. To discover more about the effect of tooth surface loss on roots we also used Eda pathway mutants, which are characterised by early loss of their tooth surface due to enamel hypoplasia. We then investigated the effect of enamel hypoplasia on the roots and showed, in keeping with our earlier results, that the roots displayed hypercementosis and changes in dimension.
In conclusion we have identified that after the cessation of root development external forces that are applied to the crowns play an important role in the future morphology and composition of roots. We show that such changes in the roots are generated by alterations in cementum production, which should be taken into account especially during orthodontic treatment, as teeth with hypercementosis are difficult to move or be removed.
|Date of Award
|Abigail Tucker (Supervisor), Fraser McDonald (Supervisor) & Isabelle Miletich (Supervisor)