Evaluation of permanent and primary enamel and dentin mineral density using micro-computed tomography
The present study was performed to investigate the mineral density distribution in enamel and dentin for both permanent and primary teeth and to establish the standard density per tooth type using micro-computed tomography (CT).
Fifty-seven extracted human teeth (37 permanent, 20 primary) were evaluated in the present study. The enamel and dentin mineral densities in the extracted teeth were measured using micro-CT. Cubic regression curves were used to determine the mineral density distribution in the enamel and dentin for each tooth type.
The mean values, distributions, and regression equations of the mineral densities were obtained. The mean mineral density values for permanent enamel and dentin were significantly higher than those for their primary counterparts for each tooth type.
In the present study, we demonstrated the distribution of mineral density in sound enamel and dentin and attempted to determine the standard mineral density for each tooth type using micro-CT. The mineral density distributions found in this study contribute to our understanding of the mechanical properties of enamel and dentin. A positive correlation suggests that the systemic bone mineral density could be predicted based on the analysis of exfoliated teeth, such as in patients with hypophosphatasia. The present results may be useful in establishing a numerical standard for the mechanism involved in root fracture and for early detection of root fracture risk.
KeywordsMineral density Micro-computed tomography Enamel Dentin Primary teeth
This study was supported in part by a Grant-in-Aid for Scientific Research (C) (no. 17K11665) from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
Compliance with ethical standards
Conflict of interest
Sachiko Hayashi-Sakai, Makoto Sakamoto, Takafumi Hayashi, Kaito Sugita, Jun Sakai, Junko Shimomura-Kuroki, Makiko Ike, Yutaka Nikkuni and Hideyoshi Nishiyama declare that they have no conflict of interest.
Human rights statement and informed consent
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions. Informed consent was obtained from all patients for being included in the study.
- 1.Hayashi-Sakai S, Sakai J, Sakamoto M, Kouda F, Noda T. The gradient of microhardness in cross-sectioned sound primary molars. J JSEM. 2006;6:13–8.Google Scholar
- 14.Montgomery J, Beaumont J, Mackenzie K. Timelines in teeth: using micro-CT scanning to investigate mineralization in developing human enamel. In: Bruker microCT Academy Newsletter; 2011. p. 219–21.Google Scholar