Cellular and Molecular Pathways Leading to External Root Resorption

Abstract

External apical root resorption during orthodontic treatment implicates specific molecular pathways that orchestrate nonphysiologic cellular activation. To date, a substantial number of in vitro and in vivo molecular, genomic, and proteomic studies have supplied data that provide new insights into root resorption. Recent mechanisms and developments reviewed here include the role of the cellular component-specifically, the balance of CD68 + , iNOS + M1-and CD68 + , CD163 + M2-like macrophages associated with root resorption and root surface repair processes linked to the expression of the M1-associated proinflammatory cytokine tumor necrosis factor, inducible nitric oxide synthase, the M1 activator interferon γ, the M2 activator interleukin 4, and M2-associated anti-inflammatory interleukin 10 and arginase I. Insights into the role of mesenchymal dental pulp cells in attenuating dentin resorption in homeostasis are also reviewed. Data on recently deciphered molecular pathways are reviewed at the level of (1) clastic cell adhesion in the external apical root resorption process and the specific role of α/β integrins, osteopontin, and related extracellular matrix proteins; (2) clastic cell fusion and activation by the RANKL/RANK/OPG and ATP-P2RX7-IL1 pathways; and (3) regulatory mechanisms of root resorption repair by cementum at the proteomic and transcriptomic levels.

Long‐term retention of avulsed maxillary permanent incisors replanted after prolonged non‐physiological storage

“…2 In contrast to this pathological inflammatory process, ERR is considered a physiological process of bone remodeling, which is modulated by hormones, enzymes, and the RANKL/RANK/OPG system. 15 As expected, ankylosis and ERR occurred in both teeth in the present case. However, the resorption extended very slowly, and only minor radiographic changes were observed during the follow-up period.…”

“…Due to timely initiation of root canal treatment within the first two weeks after trauma, infection of the pulp space, which would have inevitably led to external inflammatory root resorption, was prevented . In contrast to this pathological inflammatory process, ERR is considered a physiological process of bone remodeling, which is modulated by hormones, enzymes, and the RANKL/RANK/OPG system . As expected, ankylosis and ERR occurred in both teeth in the present case.…”

sRANKL and its correlation with metabolic syndrome parameters in children

“…First, we did not test the complete signal pathway molecules of the RANKL/ RANK/OPG (osteoprotegerin) system involved in root resorption repair by cementum. 26 Second, the type of diet may have been a confounding variable despite avoiding biases in the quantification of sRANKL concentrations in saliva attributed to dental replacement and bone remodelling. Notwithstanding, this study adds some valuable information to possible associations between MS parameters and higher levels of RANK in serum.…”

Heredity, genetics and orthodontics: How much has this research really helped?

“…69 In addition, the relationships between bone density, the rate of tooth movement and root resorption have been studied in lactating calcium-deficient female Sprague-Dawley rats. These studies showed that decreased alveolar bone density facilitated rapid orthodontic tooth movement, and reduced cratering of the root outer cementum, implying that there was less strain on the dental root as the tooth moved faster, with differential resorption of alveolar bone versus root structure.…”