Abstract
Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL). Our recent study indicated that occlusion regulated tooth root elongation occurs during root development in rat molars. Using a non-occlusal model established to directly examine the effects of the absence of occlusion in developing first molars of upper jaw, histological analysis was performed to count the number of HERS cells, with Microarray used to analyse gene expression profiles. HERS cell numbers in normal molars decreased significantly more than those in experimental molars. In microarray data, a total of 59 genes showed significant differences (fold change > 2.0). Expressions of 55 genes in the experimental molars, which included PLAP-1/asporin and periostin, were significantly decreased than those in normal molars. These data indicate that occlusion during root development leads to a decrease in the number of HERS cells, and that the aforementioned genes may play an essential role in normal root formation.
Highlights
Occlusion is commenced through contact between a tooth and its counterpart tooth and works as the mechanical force against the periodontal ligament (PDL)
Occlusion is commenced by contact of a tooth with an opposing tooth and is the mechanical force working against the periodontal ligament (PDL)
Hertwig’s Epithelial Root Sheath (HERS) of normal molars at 15 and 21 days old At P15, tooth cusps have not emerged into the oral cavity, but tooth root formation has commenced (Figure 1(a))
Summary
Occlusion is commenced through contact between a tooth and its counterpart tooth and works as the mechanical force against the periodontal ligament (PDL). Our recent study, which employed a non-occlusal model during root development, demonstrated that occlusion is directly related to tooth-root elongation by regulating cell proliferation of the apical region [1]. This means that as an environmental factor, occlusion is important to root formation. Studies focused on root length are very few, but Nakatomi et al has reported that mesenchymal dysplasia mice carrying an abnormal C-terminus of Patched 1 protein have shorter roots [2]. The molar roots of sulf1/sulf double knockout mice were short [3]. Factors regulating root length have remained unknown
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
