Atorvastatin-induced osteoclast inhibition reduces orthodontic relapse

Exploring the osteogenic potential of semisynthetic triterpenes from Combretum leprosum: An in vitro and in silico study

Combretum leprosum Mart. is a plant of the Combretaceae family, widely distributed in the Northeast region of Brazil, popularly used as an anti-inflammatory agent, and rich in triterpenes. This study evaluated in vitro and in silico potential osteogenic of two semisynthetic triterpenes (CL-P2 and CL-P2A) obtained from the pentacyclic triterpene 3β,6β,16β-trihydroxylup-20(29)-ene (CL-1) isolated from C. leprosum. Assays were carried out in cultured murine osteoblasts (OFCOL II), first investigating the possible toxicity of the compounds on these cells through viability assays (MTT). Cell proliferation and activation were investigated by immunohistochemical evaluation of Ki-67, bone alkaline phosphatase (ALP) activity, and mineralization test by Von Kossa. Molecular docking analysis was performed to predict the binding affinity of CL-P2 and CL-P2A to target proteins involved in the regulation of osteogenesis, including: bone morphogenetic protein 2 (BMP-2), proteins related to Wingless-related integration (WNT) pathway (Low-density lipoprotein receptor-related protein 6-LRP6 and sclerostin-SOST), and receptor activator of nuclear factor (NF)-kB-ligand (RANK-L). Next, Western Blot and immunofluorescence investigated BMP-2, WNT, RANK-L, and OPG protein expressions in cultured murine osteoblasts (OFCOL II). None of the CL-P2 and CL-P2A concentrations were toxic to osteoblasts. Increased cell proliferation, ALP activity, and bone mineralization were observed. Molecular docking assays demonstrated interactions with BMP-2, LRP6, SOST, and RANK-L/OPG. There was observed increased expression of BMP-2, WNT, and RANK-L/OPG proteins. These results suggest, for the first time, the osteogenic potential of CL-P2 and CL-P2A.

Impact of occlusal contact pattern on dental stability and oromandibular system after orthodontic tooth movement in rats

How to ensure dental stability in new positions and reduce the likelihood of relapse is a major clinical concern in the orthodontic field. Occlusal contacts between arches may affect the transmission of masticatory forces, thereby influencing the biological response of the periodontal and the oromandibular system. Occlusion factors that may influence the stability after orthodontic tooth movement (OTM) remain largely unknown. Hence, this research was conducted in order to investigate the influence of different occlusal contact patterns on tooth stability and oromandibular system including the masseter muscle and the temporomandibular joint following OTM. By modifying the occlusal surfaces, in vivo animal study models with distinct occlusal patterns corresponding to clinical circumstances were established. The relapse distance of teeth and the level of inflammatory factors in the gingival cervical fluid were analyzed. We also closely observed the histological remodeling of periodontal tissue, masseter tissue, and joint tissue after one week of relapse. Moreover, genes expression in the alveolar bone was analyzed to illustrate the potential biological mechanisms of relapse under the influence of different occlusal contact patterns following OTM. Different occlusal contact patterns after OTM in rats were established. The intercuspation contact between cusp and fossa group exhibited the lowest level of relapse movement, inflammatory factors and osteoclast activity (P < 0.05). On the other hand, groups with interferences or inadequate contacts exhibited more relapse movement, and tend to promote inflammation of periodontal tissue and activate bone resorption (P < 0.05). Adequate occlusal contacts without interference may enhance tooth stability and reduce the likelihood of relapse. After active orthodontic treatment, necessary occlusal adjustment should be made to achieve the desired intercuspation contact relationship and ensure adequate contact between the arches. The elimination of occlusal interferences is crucial to achieving optimal stability and promoting overall healthy condition of the oromandibular system.

Effects of low level laser on periodontal tissue remodeling in hPDLCs under tensile stress

This study aimed to investigate the effect of Low-Level Laser Therapy (LLLT) on human Periodontal Ligament Cells (hPDLCs) under tension stress. Primary hPDLCs were obtained using the tissue culture method, and P3 cells were utilized for the subsequent experiments. The study comprised four groups: a blank control group (Group B), a laser irradiation group (Group L), a tension stress group (Group T), and a laser + tension stress group (Group LT). Mechanical loading was applied using an in-vitro cell stress loading device at a frequency of 0.5 Hz and deformation of 2% for two hours per day for two days. Laser irradiation at 808 nm GaAlAs laser was administered 1 h after force loading. Cell samples were collected after the experiment. Bone and fiber remodeling factors were analyzed using PCR and Western blot. Flow cytometry was employed to assess the cell cycle, while ROS and Ca2+ levels were measured using a multifunctional enzyme labeling instrument. The results revealed that laser intervention under tension stress inhibited the expression of osteogenic differentiation factors, promoted the expression of osteoclast differentiation factors, and significantly increased the production of collagen factors, MMPs, and TIMPs. The LT group exhibited the most active cell cycle (P < 0.05). LLLT not only enhanced Ca2+ expression in hPDLCs under tension stress, but also stimulated the production of ROS. Overall, our findings demonstrate that LLLT effectively accelerated the proliferation of hPDLCs and the remodeling of periodontal tissue, possibly through the regulation of ROS and Ca2+ levels in hPDLCs.

A Comprehensive Review on Drug Therapies and Nanomaterials used in Orthodontic Treatment

Orthodontic treatment typically requires an extended duration of 1-2 years to complete the treatment. Accelerating the rate of tooth movement during orthodontic treatment is essential for shortening the overall treatment duration. After the completion of orthodontic treatment, a prominent concern arises in the form of orthodontic relapse, where the teeth tend to revert to their original positions. This issue affects approximately 60% of the global population, underscoring the importance of implementing effective measures to address orthodontic relapse. An approach in this regard involves the targeted administration of herbal and synthetic drugs applied directly to the specific area of interest to facilitate tooth movement and prevent orthodontic relapse. Apart from this, researchers are investigating the feasibility of utilizing different types of nanoparticles to improve the process of orthodontic tooth movement. In recent years, there has been a noticeable increase in the number of studies examining the effects of various drugs on orthodontics. However, the currently available literature does not provide significant evidence relating to orthodontic tooth movement. In this review, the authors provide valuable information about the drugs and nanomaterials that are capable of further enhancing the rate of orthodontic tooth movement and reducing the risk of orthodontic relapse. However, a notable hurdle remains, i.e., there is no marketed formulation available that can enhance orthodontic tooth movement and reduce treatment time. Therefore, researchers should try herbal-synthetic approaches to achieve a synergistic effect that can enhance orthodontic tooth movement. In this nutshell, there is an urgent need to develop a non-invasive, patient-compliant, and cost-effective formulation that will provide quality treatment and ultimately reduce the treatment time. Another critical issue is orthodontic relapse, which can be addressed by employing drugs that slow down osteoclastogenesis, thereby preventing tooth movement after treatment. Nevertheless, extensive research is still required to overcome this challenge in the future.

The Use of Polymers to Enhance Post-Orthodontic Tooth Stability

Relapse after orthodontic treatment occurs at a rate of about 70 to 90%, and this phenomenon is an orthodontic issue that has not yet been resolved. Retention devices are one attempt at prevention, but they require a considerable amount of time. Most orthodontists continue to find it challenging to manage orthodontic relapse; therefore, additional research is required. In line with existing knowledge regarding the biological basis of relapse, biomedical engineering approaches to relapse regulation show promise. With so many possible uses in biomedical engineering, polymeric materials have long been at the forefront of the materials world. Orthodontics is an emerging field, and scientists are paying a great deal of attention to polymers because of their potential applications in this area. In recent years, the controlled release of bisphosphonate risedronate using a topically applied gelatin hydrogel has been demonstrated to be effective in reducing relapse. Simvastatin encapsulation in exosomes generated from periodontal ligament stem cells can promote simvastatin solubility and increase the inhibitory action of orthodontic relapse. Moreover, the local injection of epigallocatechin gallate-modified gelatin suppresses osteoclastogenesis and could be developed as a novel treatment method to modify tooth movement and inhibit orthodontic relapse. Furthermore, the intrasulcular administration of hydrogel carbonated hydroxyapatite-incorporated advanced platelet-rich fibrin has been shown to minimize orthodontic relapse. The objective of this review was to provide an overview of the use of polymer materials to reduce post-orthodontic relapse. We assume that bone remodeling is a crucial factor even though the exact process by which orthodontic correction is lost after retention is not fully known. Delivery of a polymer containing elements that altered osteoclast activity inhibited osteoclastogenesis and blocking orthodontic relapse. The most promising polymeric materials and their potential orthodontic uses for the prevention of orthodontic relapse are also discussed.

Simvastatin encapsulated in exosomes can enhance its inhibition of relapse after orthodontic tooth movement

INTRODUCTION

Relapse after orthodontic treatment is a major clinical issue in the dental field. Studies indicate that simvastatin may, to some extent, decrease the rate and magnitude of relapse status. Recent evidence demonstrated that exosome-based drug delivery has a broad prospect of clinical application. Hence, this study investigates whether simvastatin encapsulated in exosomes can inhibit relapse after orthodontic tooth movement (OTM).

METHODS

Periodontal ligament stem cells (PDLSCs) and their exosomes (PDLSCs-Exo) were isolated and identified. Exosomal simvastatin was obtained by co-incubation of simvastatin and PDLSCs-Exo. An OTM rat model was established. During the relapse period, rats' local alveolar bone was injected with simvastatin, PDLSCs-Exo, and exosomal simvastatin to examine the effect on relapse. Finally, we analyzed the influence of exosomal simvastatin on osteogenesis at the molecular and histologic levels.

RESULTS

PDLSCs and PDLSCs-Exo were successfully extracted and characterized by multiple means. Simvastatin encapsulated in exosomes can increase the solubility of the drug. Exosomal simvastatin can enhance its inhibition of relapse after OTM in the rat model. The expression level of osteogenic-related genes and proteins in the exosomal simvastatin group is higher than in other groups. Histologic analysis showed a reduction of bone-resorptive lacunae in the exosomal simvastatin group.

CONCLUSIONS

Encapsulating simvastatin into the exosomes derived from PDLSCs can improve simvastatin solubility and enhance the inhibition effect of relapse in the rat model of OTM. Notably, local injection of PDLSCs-Exo alone can also block the relapse after OTM.

The Impact of Atorvastatin on RANKL Expression in Rats during the Retention Stage after Orthodontic Tooth Movement

Objective

To probe into the impact of atorvastatin on RANKL expression in rats during the retention stage after orthodontic tooth movement and its associated molecular mechanisms.

Methods

After establishing an orthodontic tooth movement model, the left teeth of the retention-stage rats were the maintained side, and the right teeth were the nonmaintained side, which were given physiological saline or atorvastatin dosing at 7d, 14d, and 21d, respectively, by tube feeding, in order to keep the rats as a control group at the beginning of the retention stage. A model of the rat's upper jaw gypsum in each group was made at various time points to measure the distance at which the teeth relapsed. The pathological slices of the upper jaw arch were taken separately for TRAP staining observation.

Results

Compared to the physiological saline group, the recurrence distance of rats in the atorvastatin group was visually lower (p < 0.05), and the number of bone-breaking cells was signally lower (p < 0.05); P-5b, PTH, VitD3, GC, IL-1, and IL-17 expressions (p < 0.05) were visually decreased, while IL-11 expression was elevated (p < 0.05).

Conclusion

The atorvastatin given to rats during the retention stage after orthodontic tooth movement inhibits RANKL expression and may function through OPG/RANKL/RANK system.

Three-dimensional imaging and molecular analysis of the effects of photobiomodulation and mechanical vibration on orthodontic retention treatment in rats : Effects of photobiomodulation and mechanical vibration on orthodontic retention treatment

PURPOSE

We aimed to evaluate and compare effects of photobiomodulation (PBM) and low-magnitude high-frequency mechanical vibration (HFMV) on orthodontic retention.

METHODS

Sixty-four female Wistar albino rats were divided into 9 groups (2 negative and positive controls each, 3 PBM and 2 HFMV groups) and studied for 25 days. In the experimental groups, closed nickel-titanium closed coil springs with a 50 cN force were placed for 10 days between the maxillary incisor and molar. PBM and HFMV were applied daily over long- (15 days) and short-term (7 days) retention periods. The PBM groups received PBM with a single wavelength (650 nm) or higher wavelengths (532, 650, 940 nm) for 9 min per day. HFMV groups received HFMV of 10, 20, and 30 Hz for 10 min per day. Right and left maxilla were assessed using micro-computed tomography imaging and real-time polymerase chain reaction. The amount of tooth movement during the retention period, expression levels of cyclooxygenase‑2 (COX-2), osteoprotegerin (OPG), and receptor activator of nuclear factor-kappa B ligand (RANKL) mRNA gene expression levels, OPG/RANKL ratios, alveolar bone trabecular thickness (Tb.Th), trabecular number (Tb.N), and structure model index were analyzed. Kruskal-Wallis and Mann-Whitney U tests were used for multiple comparisons of the nonparametric distributed data and binary comparisons, respectively.

RESULTS

When using the long-term retention protocol, PBM and HFMV treatment increased Tb.N (p < 0.05) and decreased COX‑2 mRNA gene expression levels (p < 0.05) and Tb.Th (p < 0.05) compared to controls. For short-term retention, PBM and HFMV decreased the amount of relapse tooth movement compared to controls. In addition, Tb.Th (p < 0.05) and the mRNA gene expression levels of COX‑2 and RANKL (p < 0.05) were decreased.

CONCLUSION

PBM and HFMV might be able to support retention after orthodontic tooth movement by reducing bone resorption and increasing bone quality.

Raloxifene administration enhances retention in an orthodontic relapse model

BACKGROUND AND OBJECTIVES

Orthodontic relapse is a physiologic process that involves remodelling of the alveolar bone and principle periodontal ligament fibres. Raloxifene is an Food and Drug Administration (FDA)-approved selective oestrogen receptor modulator that inhibits systemic bone loss. In our study, we examined the effects of Raloxifene on alveolar bone modelling and orthodontic relapse in a rodent model.

MATERIALS AND METHODS

The efficacy of raloxifene was evaluated in 15-week-old male Wistar rats, 8 in each group (Control, Raloxifene, Raloxifene + 7-day relapse, Raloxifene + 14-day relapse) for a total of 42 days. All animals had 14 days of orthodontic tooth movement with a closed nickel-titanium coil spring tied from incisors to right first molar applying 5-8 gm of force. On the day of appliance removal, impression was taken with silicon material and the distance between first molar and second molar was filled with light-cured adhesive resin cement for retention phase. Raloxifene Retention, Raloxifene Retention + 7D, Raloxifene Retention + 14D groups received 14 daily doses of raloxifene (2.0 mg/kg/day) subcutaneously after orthodontic tooth movement during retention. After 14 days of retention, the retainer was removed and right first molar was allowed to relapse for a period of 14 days. Raloxifene injection continued for the Raloxifene + 14-day relapse group during relapse phase too. Control group received saline injections during retention. Animals were euthanized by CO2 inhalation. The outcome measure included percentage of relapse, bone volume fraction, tissue density, and histology analysis using tartrate-resistant acid phosphatase staining and determining receptor activator of nuclear factor-кB-ligand (RANKL) and osteoprotegerin expression.

RESULTS

Raloxifene Retention + 14D group had significantly less (P < 0.05) orthodontic relapse when compared with other groups. There was a significant increase (P < 0.05) in bone volume fraction and tissue density in the Raloxifene Retention + 14D group when compared with other groups. Similarly, there was significant decrease in number of osteoclasts and RANKL expression in Raloxifene Retention + 14D group when compared with Raloxifene Retention + 7D group (P < 0.05).

CONCLUSION

Raloxifene could decrease post-orthodontic treatment relapse by decreasing bone resorption and indirectly enhancing bone formation.

Could medications and biologic factors affect post-orthodontic tooth movement changes? A systematic review of animal studies

Immediately after the removal of orthodontic appliances, the teeth might start to drift away from their corrected position in an attempt to reach a new equilibrium. Medications and biologic factors could potentially modulate these processes. The objective of the present systematic review is to systematically investigate and appraise the quality of the evidence regarding the effect of various medications and biologic factors on the rate of relapse following active tooth movement. Search without restrictions in eight databases and hand searching until April 2020 were conducted. Studies performed on animal models investigating the effects of medication and biologic factors on the rate of relapse following orthodontic tooth movement were considered. Following study retrieval and selection, relevant data were extracted and the risk of bias was assessed. Seventeen studies were finally identified, mostly at either high or unclear risk of bias. Ketorolac did not show any significant effects on relapse, while the administration of tetracycline, atorvastatin, psoralen and raloxifene decreased it. Overall, the same result was observed with bisphosphonates with the exception of low dosage of risedronate, which did not have an effect. Osteoprotegerin and strontium resulted in reduced relapse, but not in the immediate post-administration period. Inconsistent or conflicting effects were noted after the use of simvastatin and relaxin. The quality of the available evidence was considered at best as low. It can be concluded that specific medications and biologic factors may have an effect on the rate of relapse following tooth movement. The orthodontist should be knowledgeable about the substances potentially affecting retention.

Effect of pharmacological agents on relapse following orthodontic tooth movement

OBJECTIVES

To investigate and synthesize systematically the evidence from animal studies pertaining to the effect of pharmacological agents on tooth movement relapse following cessation of orthodontic force application.

MATERIALS AND METHODS

An electronic search was conducted in seven online databases (including gray sources) without restrictions until the third week of April 2019, followed by a hand search in the reference lists of eligible articles. Controlled animal studies investigating the effect of pharmacological agents on tooth movement relapse following orthodontic treatment were selected. Relevant data were extracted from eligible studies and the risk of bias assessment was done using SYRCLE's risk of bias tool. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation tool.

RESULTS

The search identified 2354 records, of which 7 studies were deemed eligible for inclusion in the qualitative synthesis, with the majority presenting an unclear risk of bias. Orthodontic relapse was shown to decrease with the administration of pamidronate disodium, atorvastatin, aspirin, and chemically modified tetracycline-3. Inconsistent effects on relapse were observed after the use of simvastatin. The overall quality of retrieved evidence was assessed as low at best.

CONCLUSIONS

The available evidence shows that the investigated pharmacological agents may demonstrate variable effects on tooth movement relapse following cessation of orthodontic force. Additional evidence of higher quality is required to draw definitive conclusions on their effects and to make potential recommendations for clinical application.

The expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in the compression area during orthodontic relapse

OBJECTIVE

This study investigated the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in the compression area during orthodontic relapse in rat molars.

MATERIALS AND METHODS

Thirty Wistar rats (6 weeks old) underwent orthodontic tooth movement (OTM) of the left first maxillary molar for 21 days, followed by removal of the force device. The contralateral maxillary molar served as a control with no mechanical force stimuli. Animals were sacrificed at 0, 1, 3, 7, and 14 days of relapse after force withdrawal. Tooth relapse and alveolar bone parameters were measured using microcomputed tomography (micro-CT). Maxilla sections were obtained for haematoxylin and eosin (HE), immunohistochemical staining [EMMPRIN, nuclear factor kappa B ligand (RANKL) and vascular endothelial growth factor (VEGF)] and tartrate-resistant acid phosphatase (TRAP). Correlation analyses were then performed.

RESULTS

After force removal, nearly 79.88% of the total relapse occurred within the initial 3 days. The number of osteoclasts clearly increased while the alveolar bone density decreased on the pressure side on Day 3 of relapse. Moreover, the EMMPRIN expression level significantly increased on Day 1, peaked up on Day 3 and decreased on Days 7 and 14. Statistically, a strong positive correlation was found between EMMRPIN expression and the osteoclast number and RANKL and VEGF expression.

CONCLUSION

EMMPRIN was highly expressed on the pressure side during the orthodontic tooth relapse, which could be involved in osteoclastogenesis and alveolar bone resorption in association with RANKL and VEGF expression.

The effects of statins on dental and oral health: a review of preclinical and clinical studies

The statin family of drugs are safe and effective therapeutic agents for the treatment of arteriosclerotic cardiovascular disease (CVD). Due to a wide range of health benefits in addition to their cholesterol lowering properties, statins have recently attracted significant attention as a new treatment strategy for several conditions, which are not directly related to normalizing a lipid profile and preventing CVD. Statins exert a variety of beneficial effects on different aspects of oral health, which includes their positive effects on bone metabolism, their anti-inflammatory and antioxidant properties, and their potential effects on epithelization and wound healing. Additionally, they possess antimicrobial, antiviral, and fungicidal properties, which makes this class of drugs attractive to the field of periodontal diseases and oral and dental health. However, to the best of our knowledge, there has been no comprehensive study to date, which has investigated the effects of statin drugs on different aspects of dental and oral health. Therefore, the primary objective of this paper was to review the effect of statins on dental and oral health. Results of our extensive review have indicated that statins possess remarkable and promising effects on several aspects of dental and oral health including chronic periodontitis, alveolar bone loss due to either extraction or chronic periodontitis, osseointegration of implants, dental pulp cells, orthodontic tooth movement, and orthodontic relapse, tissue healing (wound/bone healing), salivary gland function, and finally, anti-cancer effects. Hence, statins can be considered as novel, safe, inexpensive, and widely-accessible therapeutic agents to improve different aspects of dental and oral health.

Effect of statins on orthodontic tooth movement: A systematic review of animal and clinical studies

OBJECTIVE

The objective was to systematically-review the effect of statin drugs on orthodontic-tooth-movement (OTM).

DESIGN

The focused-question was "Does statin therapy affect OTM?" PubMed, Ovid Medline, Cochrane Library, Scopus, EMBASE and Web of Science databases were searched without time and language restrictions using different key words. Studies assessing the effect of adjunctive statin administration on OTM compared with orthodontic treatment alone were included. The search was performed up to and including December 2018. Data regarding the study design/grouping, subjects, age/gender, duration of follow-up, outcome variables and parameters related to OTM and statins administration were evaluated.

RESULTS

Nine studies (1 clinical and 8 studies performed in animal-models) were included. Six studies used Simvastatin, whereas three studies used Atorvastatin. Six experimental studies and one clinical study reported reduction in OTM upon statin administration. Two experimental studies reported no effect of statin administration on OTM. In 90 % of the studies, the risk-of-bias was high.

CONCLUSION

Based upon the high risk-of-bias and methodological inconsistencies among the included studies, the influence of statin delivery on OTM remains debatable.

Sodium-chloride-induced effects on the expression profile of human periodontal ligament fibroblasts with focus on simulated orthodontic tooth movement

Increased salt (NaCl) consumption triggers chronic diseases such as hypertension or osteopenia. Its impact on orthodontic tooth movement and periodontitis, however, has not been investigated, although both processes are related to the immune system, with periodontal ligament fibroblasts (PDLFs) playing a key mediating role. Here, we investigated the impact of NaCl on the expression pattern of PDLFs in a model of simulated compressive orthodontic strain. Periodontal ligament fibroblasts were preincubated for 24 h with additional 0 or 40 mM NaCl and concurrently treated for another 48 h with or without compressive strain of 2 g cm^-2 . We analyzed the expression of genes and proteins involved in orthodontic tooth movement by reverse transcription quantitative polymerase chain reaction (RT-qPCR), ELISA, and immunoblot. Co-culture experiments were performed to observe PDLF-mediated osteoclastogenesis. A higher (40 mM) concentration of NaCl in the culture medium resulted in increased secretion of prostaglandin, expression of alkaline phosphatase, and expression of genes involved in extracellular matrix remodeling, but decreased compression-induced expression of the interleukin-6 (IL6) gene. The 40 mM concentration of NaCl also enhanced receptor activator of nuclear factor kappa-B ligand (RANKL) but reduced that of osteoprotegerin (OPG), resulting in upregulated PDLF-mediated osteoclastogenesis. A high NaCl concentration in the periodontal ligament, corresponding to a high-salt diet in vivo, may influence orthodontic tooth movement and periodontitis through increased secretion of prostaglandins by PDLFs and upregulated PDLF-mediated osteoclastogenesis, possibly accelerating orthodontic tooth movement and propagating periodontitis and periodontal bone loss.

Atorvastatin inhibits osteoclastogenesis and arrests tooth movement

INTRODUCTION

In addition to their cholesterol-lowering effects, the statin class of drugs appears to enhance osteogenesis and suppress bone resorption, which could be a clinical concern during orthodontic treatment. In this animal study, we aimed to determine whether atorvastatin (ATV) affects orthodontic tooth movement (OTM) through osteoclast inhibition. Furthermore, we analyzed the potential adverse effects of ATV on long-bone turnover and endochondral ossification.

METHODS

Rats were administered ATV (15 mg/kg) or saline solution via gavage (n = 12 animals/group), starting 2 weeks before initial OTM. Tooth displacement was measured after 7, 14, and 21 days. Histologic sections of the maxilla and femur were obtained after 14 and 21 days of OTM and stained (hematoxylin and eosin; TRAP assay) for histomorphometric analysis.

RESULTS

ATV was associated with significant (P <0.05) reductions in OTM and osteoclast counts. Independently of drug administration, OTM increased the number of osteoclasts and reduced the bone-volume ratio compared with the control maxillae without OTM. Long-term statin administration did not appear to affect femoral endochondral ossification.

CONCLUSIONS

This experimental study showed that the long-term use of ATV can significantly promote osteoclast inhibition and slow the OTM in the first week in rats. Under physiologic conditions, the drug did not affect bone turnover and endochondral ossification.