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3D analysis of mandibular deciduous tooth crypts using μCT imaging

University of British Columbia

Objectives: Interactions between the dental follicle and the alveolar bone are tightly coordinated such that the correct amount of support for each tooth is formed. Prior to root formation, bone-tooth interactions may also regulate the shape or size of the crown. Here we measure the increase in tooth and mandibular volume and then go onto to determine whether growth of each crypt is allometric or isometric. Finally we determine whether tooth shape is influenced by local factors. Methods: Fetal heads 12 to 19 weeks were obtained from BC Women’s hospital (N = 25; Protocol H08-02576). Heads were scanned at 50μm resolution, reconstructed and segmented using Amira v5.6 software. Statistical analysis included two-way ANOVA and post-hoc Tukey’s test. Landmark and Morpho J software was used for landmark-based geometric morphometrics. Results: Segmentation of the mandible and crypts revealed that the alveolar bone varied according to the tooth type, surface and age of specimen. The patterns of bone were symmetrical within each specimen. The typical pattern consisted of 1) absence of occlusal bone, 2) presence of gingival bone, 3) interproximal bone on the mesial and distal of the c, 4) varying degrees of buccal bone on the c and m1. Volumetric measurements revealed 3 periods of growth - 12-14 weeks, 15-16 weeks and 17-19 weeks. 3D morphometrics revealed that the buccal landmarks of m1 and c were displaced buccally, gingival landmarks for i1, i2 and c were displaced gingivally and distal landmarks on m2 were displaced mesially. Conclusions: The surprising regional differences in the presence of bone on different sides of the follicle suggests that there must be local signaling mechanisms at work. The high degree of symmetry between the right and left sides further suggests that these regional patterning mechanisms are controlled by genetic rather than environmental mechanisms.

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2016-08-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/58910

Craniofacial Science

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/