Root resorption and ensuing cementum repair by Wnt/β-catenin dependent mechanism.

Abstract

INTRODUCTION:

Physiological root resorption is a common occurrence in mammalian teeth, which suggests that there must be a corollary consisting of physiological cementum repair. The mechanism(s) responsible for this physiological repair process is unknown and was the focus of this study.

METHODS:

Using a rat model, we explored first the prevalence of physiological root resorption and then asked whether this prevalence changed as a result of an osteoporotic phenotype. The cellular mechanisms of resorption were characterized using a combination of finite element modeling coupled with in-vivo histologic, molecular, and cellular analyses in rats. A potential molecular mechanism for cementum repair was uncovered using a strain of transgenic mice in which Wnt-responsive cells could be labeled and followed over time.

RESULTS:

In rats, most resorption lacunae were concentrated on the distal surfaces of the roots. Rat molars undergo a physiological tooth drift distally, and using finite element modeling, we calculated the magnitude of the compressive strains that accumulated on these surfaces in response to mastication. Although the overall strain magnitudes were low, they were constant and coincided with the presence of resorption lacunae. Where resorption lacunae were present, progeny from a Wnt-responsive population of stem cells, embedded in the periodontal ligament, directly contributed to the repair of the lacunae.

CONCLUSIONS:

Despite the fact that both are clastic conditions, an osteoporotic phenotype in rats was not associated with an increase in the prevalence of physiological root resorption. The location of the resorption lacunae corresponded to sites of low but constant compressive strains produced by physiological distal drift. At least 1 mechanism responsible for physiological cementum repair involved the contribution of Wnt-responsive stem or progenitor cells originating in the periodontal ligament. These data point toward a potential Wnt-based strategy to regenerate cementum in subjects with disease or damage.

• Authors: Hakan Turkkahraman, Xue Yuan, Benjamin Salmon, Chih-Hao Chen, John B Brunski, Jill A Helms
• Journal: American journal of orthodontics and dentofacial orthopedics : official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics (Am J Orthod Dentofacial Orthop) Vol. 158 Issue 1 Pg. 16-27 (Jul 2020) ISSN: 1097-6752 [Electronic] United States
• PMID: 32381434 (Publication Type: Journal Article)
• Copyright: Copyright © 2020 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Chemical References

• beta Catenin

Topics

• Animals
• Dental Cementum
• Mice
• Periodontal Ligament
• Rats
• Root Resorption
• Tooth Migration
• Tooth Root
• beta Catenin