Histological analysis of orthodontic root resorption in rats treated with the cyclooxygenase-2 (COX-2) inhibitor celecoxib

Caffeine induces alveolar bone loss in rats submitted to orthodontic movement via activation of receptor activator of nuclear factor ҡB, receptor activator of nuclear factor ҡB ligand, and osteoprotegerin pathway

INTRODUCTION

Caffeine is a widely consumed substance with several effects on bone metabolism. This study aimed to investigate the effect of caffeine on the bone tissue of rats submitted to orthodontic movement.

METHODS

Twenty-five male Wistar rats underwent orthodontic movement (21 days) of the first permanent maxillary molars on the left side. The experimental group (caffeine; n = 13) and control group (n = 12) received caffeine and water, respectively, by gavage. Microcomputed tomography was performed to analyze orthodontic movement. Histologic analysis of the inflammatory infiltrate and osteoclast count by tartrate-resistant acid phosphatase were conducted. Maxilla tissue was evaluated for receptor activator of nuclear factor ҡB (RANK), RANK ligand (RANKL), and osteoprotegerin by immunohistochemistry.

RESULTS

Caffeine exhibited a lower bone volume/tissue volume ratio (78.09% ± 5.83%) than the control (86.84% ± 4.89%; P <0.05). Inflammatory infiltrate was increased in the caffeine group compared with the control group (P <0.05). A higher number of tartrate-resistant acid phosphatase-positive cells was observed in the caffeine (9.67 ± 1.73) than in the control group (2.66 ± 0.76; P <0.01). Immunoexpression of RANK and RANKL in the caffeine group was greater than the control (P <0.05).

CONCLUSIONS

The use of caffeine thermogenic induces alveolar bone loss in rats submitted to orthodontic movement via activation of RANK, RANKL, and osteoprotegerin signaling pathways.

Effect of Serum Level of Vitamin D on External Apical Root Resorption in Maxillary Anterior Teeth in Patients under Fixed Orthodontic Treatment

Introduction

This study aimed to assess the effect of serum level of vitamin D on external apical root resorption (EARR) in maxillary anterior teeth in patients under fixed orthodontic treatment.

Materials and Methods

This retrospective cohort was conducted on patients under fixed orthodontic treatment who were between 12 to 30 years of age. All patients underwent the same treatment technique by the same orthodontist using a 0.022 MBT system. EARR in maxillary anterior teeth was evaluated on pre- and postoperative panoramic radiographs. Blood samples were also collected from patients, and their serum level of vitamin D was measured after the completion of treatment. Data were analyzed by independent t-test and Chi-square test (alpha = 0.05).

Results

A reduction in root length was noted in all patients, which was significant (P < 0.0001); 75% of patients showed EARR in at least one maxillary incisor. EARR had no significant correlation with the serum level of vitamin D (P=0.423).

Conclusions

Serum level of vitamin D had no significant correlation with the occurrence of EARR. However, the high prevalence of EARR calls for measures to minimize it.

Effects of systemic medication on root resorption associated with orthodontic tooth movement: a systematic review of animal studies

BACKGROUND

Theoretically, root resorption could be modulated by any medication taken that exhibits possible effects on the implicated molecular pathways.

OBJECTIVES

To systematically investigate and appraise the quality of the available evidence from animal studies, regarding the effect of commonly prescribed systemic medication on root resorption associated with orthodontic tooth movement.

SEARCH METHODS

Search without restrictions in eight databases (PubMed, Central, Cochrane Database of Systematic Reviews, SCOPUS, Web of Science, Arab World Research Source, ClinicalTrials.gov, ProQuest Dissertations and Theses Global) and hand searching until April 2018 took place. One author developed detailed search strategies for each database that were based on the PubMed strategy and adapted accordingly.

SELECTION CRITERIA

Controlled studies investigating the effect of systemic medications on root resorption associated with orthodontic tooth movement.

DATA COLLECTION AND ANALYSIS

Following study retrieval and selection, relevant data were extracted and the risk of bias was assessed using the SYRCLE's Risk of Bias Tool.

RESULTS

Twenty-one studies were finally identified, most of which at unclear risk of bias. Root resorption was shown to increase in Vitamin C treated animals in comparison with the control group, whereas a comparative decrease was noted after the administration of the alendronate, ibuprofen, growth hormone, low doses of meloxicam, simvastatin, lithium chloride and strontium ranelate. No difference was noted for acetaminophen, aspirin, fluoxetine, atorvastatin, misoprostol, zoledronic acid and zinc. Finally, inconsistent effects were observed after the administration of celecoxib, prednisolone and L-thyroxine. The quality of the available evidence was considered at best as low.

CONCLUSIONS

The pharmaceutical substances investigated were shown to exhibit variable effects on root resorption. Although the overall quality of evidence provides the clinician with a cautious perspective on the strength of the relevant recommendations, good practice would suggest that it is important to identify patients consuming medications and consider the possible implications.

REGISTRATION

PROSPERO (CRD42017078208).

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.

Comparisons of orthodontic root resorption under heavy and jiggling reciprocating forces during experimental tooth movement in a rat model

OBJECTIVE

Root mobility due to reciprocating movement of the tooth (jiggling) may exacerbate orthodontic root resorption (ORR). "Jiggling" describes mesiodistal or buccolingual movement of the roots of the teeth during orthodontic treatment. In the present study, buccolingual movement is described as "jiggling." We aimed to investigate the relationship between ORR and jiggling and to test for positive cell expression in odontoclasts in resorbed roots during experimental tooth movement (jiggling) in vivo.

METHODS

Male Wistar rats were divided into control, heavy force (HF), optimal force (OF), and jiggling force (JF) groups. The expression levels of cathepsin K, matrix metalloproteinase (MMP)-9 protein, interleukin (IL)-6, cytokine-induced neutrophil chemoattractant 1 (CINC-1; an IL-8-related protein in rodents), receptor activator of nuclear factor κB ligand (RANKL), and osteoprotegerin protein in the dental root were determined using immunohistochemistry.

RESULTS

On day 21, a greater number of root resorption lacunae, which contained multinucleated odontoclasts, were observed in the palatal roots of rats in the JF group than in rats from other groups. Furthermore, there was a significant increase in the numbers of cathepsin K-positive and MMP-9-positive odontoclasts in the JF group on day 21. Immunoreactivities for IL-6, CINC-1, and RANKL were stronger in resorbed roots exposed to jiggling than in the other groups on day 21. Negative reactivity was observed in the controls.

CONCLUSIONS

These results suggest that jiggling may induce ORR via inflammatory cytokine production during orthodontic tooth movement, and that jiggling may be a risk factor for ORR.

Celecoxib treatment does not alter recruitment and activation of osteoclasts in the initial phase of experimental tooth movement

In a previous study, we reported that the short-term treatment with celecoxib, a non-steroidal anti-inflammatory drug (NSAID) attenuates the activation of brain structures related to nociception and does not interfere with orthodontic incisor separation in rats. The conclusion was that celecoxib could possibly be prescribed for pain in orthodontic patients. However, we did not analyze the effects of this drug in periodontium. The aim of this follow-up study was to analyze effects of celecoxib treatment on recruitment and activation of osteoclasts and alveolar bone resorption after inserting an activated orthodontic appliance between the incisors in our rat model. Twenty rats (400–420 g) were pretreated through oral gavage with celecoxib (50 mg/kg) or vehicle (carboxymethyl-cellulose 0.4%). After 30 min, they received an activated (30 g) orthodontic appliance, set not to cause any palate disjunction. In sham animals, the appliance was immediately removed after introduction. All animals received ground food and, every 12 h, celecoxib or vehicle. After 48 h, they were anesthetized and transcardiacally perfused through the aorta with 4% formaldehyde. Subsequently, maxillae were removed, post-fixed and processed for histomorphometry or immunohistochemical analyses. As expected, incisor distalization induced an inflammatory response with certain histological changes, including an increase in the number of active osteoclasts at the compression side in group treated with vehicle (appliance:32.2±2.49 vs sham: 4.8±1.79, P<0.05) and celecoxib (appliance: 31.0±1.45 vs sham: 4.6±1.82, P<0.05). The treatment with celecoxib did not modify substantially the histological alterations and the number of active osteoclasts after activation of orthodontic appliance. Moreover, we did not see any difference between the groups with respect to percentage of bone resorption area. Taken together with our previous results we conclude that short-term treatment with celecoxib can indeed be a therapeutic alternative for pain relieve during orthodontic procedures.