Receptor activator of nuclear factor-kappa B is enriched in CD9-positive extracellular vesicles released by osteoclasts

Aim

Receptor activator of nuclear factor-kappa B (RANK)-containing extracellular vesicles (EVs) bind RANK-Ligand (RANKL) on osteoblasts, and thereby simultaneously inhibit bone resorption and promote bone formation. Because of this, they are attractive candidates for therapeutic bone anabolic agents. Previously, RANK was detected in 1 in every 36 EVs from osteoclasts by immunogold electron microscopy. Here, we have sought to characterize the subpopulation of EVs from osteoclasts that contains RANK in more detail.

Methods

The tetraspanins CD9 and CD81 were localized in osteoclasts by immunofluorescence. EVs were visualized by transmission electron microscopy. A Single Particle Interferometric Reflectance Imaging Sensor (SP-IRIS) and immunoaffinity isolations examined whether RANK is enriched in specific types of EVs.

Results

Immunofluorescence showed CD9 was mostly on or near the plasma membrane of osteoclasts. In contrast, CD81 was localized deeper in the osteoclast's cytosolic vesicular network. By interferometry, both CD9 and CD81 positive EVs from osteoclasts were small (56-83 nm in diameter), consistent with electron microscopy. The CD9 and CD81 EV populations were mostly distinct, and only 22% of the EVs contained both markers. RANK was detected by SP-IRIS in 2%-4% of the CD9-containing EVs, but not in CD81-positive EVs, from mature osteoclasts. Immunomagnetic isolation of CD9-containing EVs from conditioned media of osteoclasts removed most of the RANK. A trace amount of RANK was isolated with CD81.

Conclusion

RANK was enriched in a subset of the CD9-positive EVs. The current study provides the first report of selective localization of RANK in subsets of EVs.

Correlation between pain and hyalinization during tooth movement induced by different types of force

OBJECTIVES

To evaluate the correlation between pain and tissue reactions during induced tooth movement (ITM).

MATERIALS AND METHODS

Forty-two male Wistar rats (Rattus norvegicus; ∼90 days of age, 300 g) were used. The animals were divided into seven groups of six rats each: one control group and six experimental groups subjected to ITM by continuous force (CF) or interrupted continuous force (ICF) for 1, 3, and 5 days. Hyalinization of the periodontal ligament (PL) and occurrence of pain were observed. Animal behavior (walking, climbing, immobile posture, resting/sleeping, and directed face grooming) and the presence of chemical mediators associated with nociception, cyclooxygenase-2 (COX-2), and interleukin-1 beta (IL-1β) in the PL were analyzed.

RESULTS

There was a moderate positive correlation between hyalinization and the presence of COX-2 (r_s = 0.404; P < .05) and IL-1β (r_s = 0.429; P < .05). There was a moderate negative correlation between hyalinization and exploratory behaviors (walking, r = -0.586, P < .01; climbing, r = -0.573, P < .01), and a moderate positive correlation between hyalinization and resting/sleeping (r = 0.467; P < .01).

CONCLUSIONS

The results suggest a correlation between pain and undesirable tissue reactions in ITM.

Treatment of Extrusive Luxation in Permanent Teeth: Literature Review with Systematic Criteria

INTRODUCTION

Extrusive luxation is a traumatic dental injury caused by the action of oblique forces, characterized by partial displacement of the tooth out of its socket. The ideal treatment for this type of trauma involves repositioning the tooth in its socket. However, in cases where the tooth cannot be repositioned, different options may be considered, such as intentional reattachment and orthodontic intrusion. The aim is to review the literature on the extrusive luxation of permanent teeth while assessing the risks of complications for two methods of delayed treatment for extrusive luxation.

MATERIALS AND METHODS

An electronic search from August 2005 to August 2014 was performed by two reviewers independently, and conflicts were resolved by a third reviewer. The databases used were PubMed and Scopus; the reviewers performed a manual search of the following journals: Dental Traumatology, American Journal of Orthodontics, and Clinical Oral Investigation.

RESULTS

After removing the duplicate studies, 328 articles were found. Out of these, 321 were rejected as not addressing the proposed research topic. In addition, five articles were excluded because apical repositioning was used for treatment. Therefore, four articles formed the basis of the study.

CONCLUSION

Factors, such as root formation, the degree of tooth mobility, and the presence of tooth vitality were decisive for the choice of treatment. However, both treatments were effective and showed favorable results, i.e., without periodontal and root damage.

CLINICAL SIGNIFICANCE

Knowledge of the risks of complications among two methods of delayed treatment for extrusive luxation, as well as other important factors to take into consideration when choosing a treatment assists dentists in improving the prognostic.

Pain and Tissue Damage in Response to Orthodontic Tooth Movement: Are They Correlated?

AIM

To evaluate the correlation between pain and tissue damage in response to orthodontic tooth movement (OTM), such as hyalinization and external apical root resorption (EARR).

MATERIALS AND METHODS

The literature review was used as a methodological strategy, following the knowledge development process - constructivist (ProKnow-C). Study axes were defined and keywords that best represented each axis were selected. The terms were submitted to an adherence test and validation, resulting in 12 keyword combinations. Searches were carried out in the most representative databases for the selected terms, without restriction as for language or publication dates. Retrieved studies were filtered using the EndNote X6 program and classified according to analysis of title, abstract, and keywords. The final portfolio of articles was submitted to bibliometric and systematic analysis.

RESULTS

A total of 1,091 studies were retrieved, out of which 719 were repeated and 335 were removed in the classification stage. A total of 37 articles remained in the final portfolio. Only one article was in line with the purpose of this study, indicating absence of correlation between pain and EARR in response to OTM.

CONCLUSION

Further studies are necessary to confirm whether orthodontic pain might serve as a criterion for the use of appropriate mechanical forces, contributing to minimize tissue damage following OTM.

CLINICAL SIGNIFICANCE

This article presents a systematic literature review, in which scientific evidence of the correlation between pain and tissue damage during orthodontic movement was studied, providing a scientific answer for the following question: Is pain reported by patients associated with application of inappropriate orthodontic force? Thus, it aims at aiding the orthodontist in the definition of clinical parameters for the use of optimal orthodontic force.