Effect of alendronate sodium on tooth movement in ovariectomized rats

The crucial role of beta-catenin in the osteoprotective effect of semaglutide in an ovariectomized rat model of osteoporosis

Postmenopausal osteoporosis is a common chronic medical illness resulting from an imbalance between bone resorption and bone formation along with microarchitecture degeneration attributed to estrogen deficiency and often accompanied by other medical conditions such as weight gain, depression, and insomnia. Semaglutide (SEM) is a recently introduced GLP-1 receptor agonist (GLP-1RA) for the treatment of obesity and type 2 diabetes mellitus by mitigating insulin resistance. It has been discovered that the beneficial effects of GLP-1 are associated with alterations in lipolysis, adipogenesis, and anti-inflammatory processes. GLP-1 analogs transmit signals directly to adipose tissue. Mesenchymal stem cells (MSCs) are multidisciplinary cells that originate from bone marrow, migrate to injury sites, and promote bone regeneration. MSCs can differentiate into osteoblasts, adipose cells, and cartilage cells. Our aim is to investigate the role of semaglutide on bone formation and the Wnt signaling pathway. Osteoporosis was induced in female rats by ovariectomy, and the ovariectomized rats were treated with alendronate as standard treatment with a dose of 3 mg/kg orally and semaglutide with two doses (150 mcg/kg and 300 mcg/kg) S.C. for 10 successive weeks. Semaglutide ameliorates bone detrimental changes induced by ovariectomy. It improves bone microarchitecture and preserves bone mineral content. Semaglutide ameliorates ovariectomy-induced osteoporosis and increases the expression of β-catenin, leading to increased bone formation and halted receptor activator of nuclear factor kappa-Β ligand (RANKL's) activation. Semaglutide can be used as a potential prophylactic and therapeutic drug against osteoporosis, possibly by activating Wnt signaling and decreasing bone resorption.

Effect of anti-sclerostin antibody on orthodontic tooth movement in ovariectomized rats

BACKGROUND

This study aimed to evaluate the effect of systemically administered anti-sclerostin antibodies (Anti-Scl Ab) on orthodontic tooth movements (OTM) in an ovariectomized rat.

METHODS

Twenty-four 12-week-old female Sprague-Dawley rats were randomly divided into two groups: (1) ovariectomy (OVX) group, (2) ovariectomy + romosozumab (ROMO) group. OTM was performed 8 weeks after OVX. The ROMO group received subcutaneous injections of romosozumab twice a week, starting two weeks after OVX. Eight weeks after the OVX, an orthodontic force of 50 g was measured and applied by connecting orthodontic elastic bands between the maxillary first molar and a mini-screw to facilitate tooth movement (orthodontic treatment). Subsequently, the three rats were sacrificed on days 5, 7, 10, and 14. The plaster models were scanned to measure the amount of tooth movement. The effects on alveolar bone and periodontal tissues were evaluated through micro-computed tomography (micro-CT) analysis, tartrate-resistant acid phosphatase (TRAP) staining, and immunohistochemistry (IHC) analysis.

RESULTS

The ROMO group showed more tooth movement on day 7 of orthodontic treatment. Conversely, on days 10 and 14, relatively less movement was observed. Analysis of the root furcation area of the maxillary first molars revealed that from the 7th day, BV/TV, Tb.N., Tb.Th. increased, while Tb.Sp. decreased in the ROMO group. More TRAP-positive cells were observed in the compression side of the OVX group, the ROMO group exhibited a marked decrease in the positive expression of the RANKL, OPG, and sclerostin. The OPG/RANKL ratio showed significant differences in expression between the two groups. The ROMO group exhibited a higher OPG/RANKL ratio than the OVX group, and the tension side exhibited a higher OPG/RANKL ratio demonstrating significant differences.

CONCLUSION

Romosozumab initially accelerated tooth movements, but later decreased tooth movement. As new alveolar bone is formed, the micro-CT parameters are also improved. Osteoclasts, RANKL, OPG, and sclerostin decreased, while the OPG/RANKL ratio became higher.

Jaw osteoporosis: Challenges to oral health and emerging perspectives of treatment

Osteoporosis is a prevalent bone metabolic disease that poses a significant challenge to global human health. Jaw osteoporosis, characterized by microstructural damage of the jaw resulting from various factors, is one of the common manifestations of this condition. Recent studies have demonstrated that jaw osteoporosis has multifaceted effects on oral health and can negatively impact conditions such as periodontitis, oral implantation, orthodontic treatment, and wound healing. However, there are still some limitations in the conventional treatment of osteoporosis. For instance, while bisphosphonates can enhance bone quality, they may also lead to osteonecrosis of the jaw, which poses a potential safety hazard in oral diagnosis and treatment. In recent years, considerable attention has been focused on improving the pathological condition of jaw osteoporosis. Treatment strategies such as gut microbial regulation, extracellular vesicles, molecular targeted therapy, herbal medicine, mechanical stimulation are expected to enhance efficacy and minimize adverse reactions. Therefore, understanding these effects and exploring novel treatments for jaw osteoporosis may provide new insights for oral health maintenance and disease treatment. This article reviews the impact of jaw osteoporosis on oral health and describes the limitations associated with current methods. It also discusses emerging perspectives on treatment, offering a comprehensive overview of the challenges and future directions in managing jaw osteoporosis.

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.

How does alendronate affect orthodontic tooth movement in osteogenesis imperfecta: an in vivo study on a mice model

OBJECTIVES

The purpose of this study was to evaluate the effects of alendronate on orthodontic tooth movement (OTM) and bone modelling/remodelling in an osteogenesis imperfecta (OI) mice model.

MATERIALS AND METHODS

Ten-week-old male and female OI mice (Col1a2oim, n = 32) were divided into four groups: 1. Alendronate male (AM, n = 8), 2. Alendronate female (AF, n = 8), 3. saline male (SM, n = 8), and 4. saline female (SF, n = 8). The mice in all four groups received either Alendronate (0.05 mg/kg) or vehicle (saline 0.05 mg/kg) subcutaneously for 2 weeks prior to the placement of orthodontic spring. A nickel-titanium spring applying 3-5 cN of force was used to perform the OTM for 1 week. After 7 days of OTM, the OI mice were euthanized with CO2 inhalation and microfocus computed tomography and histological analyses were performed.

RESULTS

AM and AF mice showed a significant decrease (P < 0.05) in the rate of OTM compared with SM and SF mice, respectively. In addition, AM and AF mice showed a significant increase (P < 0.05) in the bone volume fraction (BVF) and tissue density (TD) compared with SM and SF mice. Histological analysis of haematoxylin-eosin staining revealed a hyalinization zone in AM and AF mice compared with SM and SF mice. Furthermore, tartrate-resistant acid phosphatase staining indicated decreased number of osteoclasts in AM and AF mice compared with SM and SF mice. Picrosirius red staining showed, Alendronate treatment led to thick uniform and smooth morphology of collagen fibres as compared with saline group. Similarly, second harmony generation images also revealed thicker collagen fibres at the periodontal ligament (PDL)-cementum entheses and PDL-alveolar bone entheses in AM and AF mice compared with SM and SF mice.

CONCLUSIONS

Alendronate led to a decrease in the rate of OTM, increase in BVF and TD, decrease in the number of osteoclasts, and smooth and thick collagen fibres compared with saline in both male and female OI mice.

The potential anti-osteoporotic effect of exercise-induced increased preptin level in ovariectomized rats

Osteoporosis increases bone fragility and fractures. Preptin hormone is regulated by moderate exercise training and increases bone formation. Therefore, this study was conducted to see how estradiol administration and moderate exercise training affected osteoporotic changes in ovariectomized (OVX) rats. To achieve this aim, 36 healthy adult female Wistar albino rats were randomized into Sham, OVX, ovariectomized estradiol-treated (OVX + E) (OVX + E rats were treated using subcutaneous estradiol benzoate 2.5 μg/kg body weight/day), ovariectomized practicing moderate exercise training, ovariectomized estradiol-treated and practiced a moderate exercise training, and ovariectomized alendronate-treated (OVX + Alen) (OVX + Alen rats were treated orally with alendronate 3 mg/kg body weight/week) groups. Alendronate was used as a standard anti-osteoporotic drug. Moderate exercise training, including therapy with estradiol and alendronate for OVX rats began on the fourth week and lasted for six weeks. Results showed that OVX rats had estrogen and preptin deficiency in serum. These deficiencies were associated with a significant increase in bone resorption biomarkers (urinary deoxypyridinoline and hydroxyproline), and bone formation biomarkers (serum osteocalcin and bone-specific alkaline phosphatase). Also, serum pro-inflammatory cytokines (tumor necrosis factor alpha and interleukin-6) were increased, while bone osteopontin (OPN) expression was decreased. Subsequently, the osteoporotic alterations were verified based on histopathological changes. From the results, estradiol therapy and moderate exercise training significantly improved these findings to the same extent as that of the standard alendronate treatment. Therefore, through their anti-inflammatory properties, increasing bone OPN expression, and regulating serum preptin; estradiol therapy and moderate exercise training can reduce osteoporotic alterations in OVX rats. Thus, combined estradiol therapy and moderate exercise training could be a promising potential therapeutic protocol to reduce postmenopausal osteoporosis. Also, targeting serum preptin and bone osteopontin regulation could have a critical role in the treatment of postmenopausal osteoporosis.

Efficacy of the systemic co-administration of vitamin D3 in reversing the inhibitory effects of sodium alendronate on orthodontic tooth movement: A preliminary experimental animal study

INTRODUCTION

Bisphosphonates can severely slow down orthodontic tooth movement (OTM) by reducing bone turnover. This calls for materials and methods to reverse or neutralize their effects on OTM. We propose systemic vitamin D3 (D3) for this purpose.

METHODS

Thirty-two male Wistar rats were randomized into 4 groups of 8 each. Three groups were administered D3 (3 systemic doses of 24,000 IU/kg each), alendronate (ALN) (5 doses of 7 mg/kg each), and ALN+D3 (same doses as mentioned above). One group served as the negative control. The incisors were distalized at 30 g of force for 2 weeks. OTMs were measured blindly. Radicular pressure areas were searched histologically (blindly) for capillaries, Howship's lacunae, osteoclasts, and osteoblasts. Data were analyzed statistically (α = 0.05, α = 0.0083, β <0.1).

RESULTS

OTMs in the groups D3, ALN+D3, ALN, and control were 1.900 ± 0.237, 1.629 ± 0.219, 0.975 ± 0.145, and 1.565 ± 0.324 mm (analysis of variance, P <0.001), respectively. OTM in the ALN group was smaller than all other groups (Tukey, P <0.001). OTM in the D3 group was greater than in the control group (P = 0.054). The ALN+D3 group had greater OTM than the ALN group (P <0.001) but was not significantly different from the D3 (P = 0.153) or control (P = 0.951) groups. All histologic variables were significantly different across groups (Kruskal-Wallis, P <0.001). All the markers in the D3 group were more frequent than those of the other groups (Mann-Whitney U, P <0.001). There were fewer markers in the ALN group than in the control group (P ≤0.001). The ALN+D3 group had more markers than the ALN group in terms of capillaries, osteoclasts, and osteoblasts (P ≤0.007). The ALN+D3 group was similar to the control group regarding capillaries, osteoclasts, and osteoblasts (P ≥0.382).

CONCLUSIONS

Systemic vitamin D3 may accelerate OTM and increase histologic biomarkers of bone turnover. ALN reduces OTM and its histologic biomarkers. Systemic vitamin D3 can reverse this inhibitory effect of ALN on OTM back to normal.

Effect of local administration of bisphosphonate on orthodontic anchorage – A systematic review of animal studies

BACKGROUND:

Pharmacological means of anchorage control can improve patient compliance. Bisphosphonates could be helpful in orthodontic anchorage control if their actions could be localized to limit (or control) unwanted tooth movement while not interfering with the desired tooth movement.

OBJECTIVE:

This systematic review aimed to examine and evaluate the quality of all animal studies that reported the effect of locally administered bisphosphonate on limiting orthodontic tooth movement.

DATA SOURCES:

An electronic search was conducted in the PubMed-Medline, Scopus, Google Scholar, and Cochrane databases till May 2022, using the keywords anchorage, anchorage loss, molar movement, posterior tooth movement, incisor movement, incisor retraction, anterior retraction, unwanted tooth movement, tooth displacement, tooth movement forward, bisphosphonate, local bisphosphonate administration, bisphosphonate injection, and bbisphosphonate vestibular induction. Only studies involving localized bisphosphonate administration for anchorage purposes were taken into account.

DATA SELECTION:

Animal studies that simulated orthodontic tooth movement after localized injection of bisphosphonate and evaluated the rate of tooth movement were included in the review.

DATA EXTRACTION AND ANALYSIS:

The quality of the studies was assessed by using ARRIVE guidelines (Animal Research: Reporting of In Vivo Experiments). Bias in the studies was analyzed by SYRCLE's tool (Systematic Review Centre for Laboratory Animal Experimentation) for risk of bias.

RESULTS:

The search strategy yielded 925 titles. After screening, 908 articles were discarded because they did not fulfill the inclusion/exclusion criteria based on the title and abstract. The remaining 16 articles were read entirely, of which nine were excluded as they involved systemic administration of bisphosphonates. Finally, after careful consideration, seven papers that met our inclusion criteria were included in the qualitative analysis. The majority of studies were assessed to have an uncertain risk of bias, with just one deemed low risk of bias.

CONCLUSION:

This systematic review found that bisphosphonates limit orthodontic tooth movement around the application site without affecting adjacent sites. More potent bisphosphonates in smaller doses or less potent bisphosphonates in higher frequencies have been proposed to improve outcomes. However, the data quality is insufficient to recommend a protocol for bisphosphonate administration for anchoring control. Long-term studies evaluating various types, frequencies, and dosages of bisphosphonates are required to clarify the effects on orthodontic tooth movement.

REGISTRATION NUMBER FOR PROSPERO:

CRD42021224033

Enhancement of orthodontic tooth movement and root resorption in ovariectomized mice

Background/purpose

As the number of patients with osteoporosis requiring orthodontic treatment is increasing with the aging of society, it is necessary to evaluate the relations between bone metabolism in old age and orthodontic tooth movement (OTM). However, the effects of changes in bone metabolism due to osteoporosis on OTM and root resorption are still unclear. Therefore, we investigated the effects of OTM and root resorption in a mouse ovariectomy (OVX)-induced osteoporosis model.

Materials and methods

Eight-week-old female wild-type mice underwent OVX or sham surgery (Sham) as controls. One month after treatment, a nickel titanium coil spring was used to apply a mesial force to the maxillary left first molars of OVX or Sham mice for 12 days. The distance between the maxillary first molar and the second molar changed due to OTM and osteoclast formation was evaluated. The odontoclast formation and root resorption along the root surface of the distobuccal root of the first molar was also evaluated by histological analysis and scanning electron microscopy.

Results

Distance of tooth movement and osteoclast formation were significantly increased in OVX mice compared to Sham controls. Furthermore, root resorption in the mesial surface of the distal molars induced by orthodontic force was significantly increased in OVX mice.

Conclusion

The amount of OTM was significantly increased, and the accompanying root resorption was also increased in OVX mice. Therefore, attention should be paid to the risk of root resorption associated with orthodontic treatment in patients with osteoporosis.

Effect of ovariectomy-induced osteoporosis on the amount of orthodontic tooth movement: a systematic review of animal studies

BACKGROUND

Understanding the impact of osteopenia and osteoporosis on orthodontic tooth movement could be of benefit to the orthodontist, but research in humans presents practical and ethical problems. The ovariectomized animal model could provide useful information on osteoporosis.

OBJECTIVE

To compare the amount of tooth movement during or after the application of orthodontic forces between ovariectomized animals and control or sham-operated subjects.

SEARCH METHODS

Unrestricted searches in seven databases and manual searching of the reference lists in relevant studies were performed up to February 2021 (PubMed, Central, Cochrane Database of Systematic Reviews, Scopus, Web of Science, Arab World Research Source, ProQuest Dissertations, and Theses Global).

SELECTION CRITERIA

We searched for studies quantitatively comparing the amount of tooth movement during or after the application of orthodontic forces between ovariectomized animals and control or sham-operated subjects.

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. Exploratory synthesis and meta-regression were carried out using the random effects model.

RESULTS

Thirteen studies were finally selected and no specific concerns regarding bias were identified. During the active period, ovariectomy was associated with a statistically significant acceleratory effect on the rate of orthodontic tooth movement compared to non-treated rats (3 weeks; 4 studies, 0.15 mm more movement in the ovariectomized rats; 95 per cent confidence interval: 0.10-0.19; P = 0.000). Exploratory meta-regression showed that this difference could increase over time. Following force discontinuation, no statistically significant differences were observed [3 weeks; 1 study (median ± SE), Ovariectomy group: 0.30 ± 0.04 mm; Sham operation group: 0.18 ± 0.03; P = 0.1558].

CONCLUSIONS

Ovariectomy-induced osteoporosis may affect the rate of orthodontic tooth movement. Although animal studies should be approached with caution regarding their translational potential, the safe practice would suggest that one should consider potential implications.

REGISTRATION

PROSPERO (CRD42018118003).

Lithium chloride promotes osteogenesis and suppresses apoptosis during orthodontic tooth movement in osteoporotic model via regulating autophagy

Osteoporosis is a widely distributed disease that may cause complications such as accelerated tooth movement, bone resorption, and tooth loss during orthodontic treatment. Promoting bone formation and reducing bone resorption are strategies for controlling these complications. For several decades, the autophagy inducer lithium chloride (LiCl) has been explored for bipolar . In this study, we investigated the autophagy-promoting effect of LiCl on bone remodeling under osteoporotic conditions during tooth movement. Ovariectomy was used to induce osteoporosis status in vivo. The results showed that LiCl rejuvenated autophagy, decreased apoptosis, and promoted bone formation, thus protecting tooth movement in osteoporotic mice. Furthermore, in vitro experiments showed that LiCl reversed the effects of ovariectomy on bone marrow-derived mesenchymal stem cells (BMSCs) extracted from ovariectomized mice, promoting osteogenesis and suppressing apoptosis by positively regulating autophagy. These findings suggest that LiCl can significantly decrease adverse effects of osteoporosis on bone remodeling, and that it has great potential significance in the field of bone formation during tooth movement in osteoporosis patients.

The effects of calcitonin on post-orthodontic relapse in rats

Objectives

To determine the effects of systematic calcitonin administration on post‐orthodontic relapse in rat model.

Material and methods

This experimental animal model involved 36 male Wister rats. The maxillary right first molars were moved mesially, using a modified orthodontic appliance delivered 50 gm, for 14 days, retained for 4 days and left to relapse for 10 days. The study group was divided into three subgroups in which a single injection of calcitonin (20 IU/Kg), three injections of calcitonin (20 IU/Kg), each every other day, and normal saline were administered subcutaneously after orthodontic tooth movement has finished. The relapse ratio, histomorphometric analysis including osteoblasts, osteoclasts numbers and bone area and immunohistochemical analysis including the expression of receptor activator of nuclear factor kappa Β (RANK), receptor activator of nuclear factor kappa Β ligand (RANKL) and osteoprotegerin (OPG) were measured and assessed.

Results

The relapse ratio was significantly reduced in the three‐dose calcitonin group (28%) compared to the single dose calcitonin group (34%) and the control group (46%). This was accompanied by a nonsignificant increase in osteoblasts number and bone area in three‐dose calcitonin group and a nonsignificant reduction in osteoclast number. However, the immune histochemical expression of RANK, RANKL and OPG did not show statistically significant difference at the end of relapse period.

Conclusions

Systemic administration of three doses of calcitonin may minimize the relapse ratio in experimentally moved rat molars.

Microtomographic analysis of the effect of sodium alendronate on orthodontic movement in rats

OBJECTIVE

To evaluate the effect of sodium alendronate on orthodontic tooth movement in rats using microtomographic analysis.

SETTINGS AND SAMPLE POPULATION

Thirty male Wistar rats (Rattus norvegicus) were divided into three groups of 10 rats and administered saline (control), 1 mg/kg sodium alendronate or 6 mg/kg sodium alendronate, respectively.

MATERIALS AND METHODS

The drug was administered once per week for 5 weeks by gavage. Orthodontic movement was induced during the last 2 weeks of medication administration by inserting a closed nickel-titanium spring between the left upper first molar and central incisors. The opposite side served as the control. Tooth movement and bone trabeculation in the furcation region were evaluated by microtomographic analysis in the first (moved) and third (static) molars. The data were subjected to one-way or two-way ANOVA and Bonferroni test (P < .05).

RESULTS

The microtomographic images of the group that received 6 mg/kg sodium alendronate demonstrated significantly less tooth movement (P = .048), less space between the trabeculae (P = .031) and greater number of bone trabeculae (P = .033) compared to the other groups. There were no statistically significant differences in bone volume and mean trabecular thickness between the three groups. The static teeth did not show the same alterations (P > .05).

CONCLUSION

Sodium alendronate treatment reduced tooth movement in rats.

Effects of systematic bisphosphonate use in patients under orthodontic treatment: a systematic review

BACKGROUND

Bisphosphonates are a class of drugs prescribed for several osseous related disorders owing to their ability to regulate bone turnover, which could in turn affect orthodontic treatment outcomes.

OBJECTIVE

To examine the effect of bisphosphonate (BP) use on orthodontic patients through clinical and radiographic measurements.

SEARCH METHODS

Systematic and unrestricted search of 17 databases complemented with additional hand-searches were performed up to March 2019.

SELECTION CRITERIA

Articles reporting on human patients with a history of BPs administration that received orthodontic treatment were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

Data regarding the medical profile of the patients, the specific type of malocclusion and the performed treatment plan, as well as the clinical and radiographic outcomes were extracted. Quality assessment was performed by the ROBINS-I tool for the cohort studies and by a slightly modified checklist from the original one proposed by Agbabiaka et al. for the case reports.

RESULTS

7 articles (1 retrospective cohort study and 6 case reports) were eventually included in the present review including 122 subjects (29 patients and 93 controls) reporting on the clinical and radiographic changes following orthodontic treatment of patients during or after BPs use. BPs seem to have a controversial effect on the clinical and patient-reported variables, even though the majority of the included patients presented with compromised treatment results and a rather slow rate of tooth movement. Most radiographic findings revealed mild root resorption, widened periodontal ligament spaces and sclerotic changes on the surrounding alveolar bone. However, these results should be interpreted with caution, due to the limited number of the eligible articles and their limitations.

LIMITATIONS

The included studies were of rather low quality due to study design and incomplete reporting.

CONCLUSIONS AND IMPLICATIONS

BP administration seems to be associated with compromised clinical outcomes, prolonged treatment time, and moderate changes on the roots and surrounding tissues of orthodontic patients.

REGISTRATION

Non-registered.

FUNDING

None.

Bis‑enoxacin blocks alveolar bone resorption in rats with ovariectomy‑induced osteoporosis

Postmenopausal osteoporosis is a common systemic skeletal disease that is associated with estrogen‑deficiency. Bone loss associated with bisphosphonates therapy can increase the risk of developing oral osteonecrosis. Recent studies have indicated that enoxacin may inhibit osteoclast formation and bone resorption via a different mechanism from that of bisphosphonates. Therefore, the authors hypothesized that the use of an enoxacin such as bis‑enoxacin (BE) in association with bisphosphonates may be effective in the treatment of postmenopausal osteoporosis‑associated alveolar bone resorption and reduce the risk of oral osteonecrosis by allowing the dose of bisphosphonates to be reduced. A total of 30 6‑month‑old female Sprague‑Dawley rats were randomly assigned to five groups: The Sham, Vehicle, zoledronic acid (ZOL), low concentrations of BE (BE‑L) and high concentrations of BE (BE‑H) groups. The results demonstrated that the ZOL, BE‑L and BE‑H groups had an increased bone volume/tissue volume, trabecular thickness, mineral apposition rate, mineralizing surface/bone surface and a decreased trabecular separation when compared with the Vehicle group. The microscopic evaluation of histological sections clearly supported the results of the micro‑computed tomography. The number of tartrate‑resistant acid phosphatase‑positive osteoclasts was markedly decreased in the ZOL, BE‑L and BE‑H groups, indicating that BE may inhibit osteoclast formation. The anti‑resorptive effect in the BE‑H group was close to or better than that exhibited by the ZOL group; however, this effect was poorer in the BE‑L group. In conclusion, BE has the potential to block alveolar bone resorption resulting from ovariectomy‑induced osteoporosis in rats in a dose‑dependent manner.

Force-induced increased osteogenesis enables accelerated orthodontic tooth movement in ovariectomized rats

As the number of elderly orthodontic patients increases, the impact of postmenopausal osteoporosis on orthodontic tooth movement (OTM) has attracted a great deal of attention because OTM relies on alveolar bone remodeling. The question of whether OTM causes subsequent alveolar bone loss and is harmful to alveolar bone health under osteoporotic conditions remains to be answered. The present study aimed to clarify the influences of OTM on alveolar bone in osteoporotic rats. OTM was accelerated in ovariectomized (OVX) rats as a result of increased bone resorption in the pressure area. At the same time, anabolic bone formation was promoted in the tension area during OTM in OVX rats. Micro-CT analysis of alveolar bone revealed a decrease in BMD, BV/TV and Tb.Th. in the OTM group compared with that in non-OTM rats on day 21 of OTM, suggesting that OTM caused alveolar bone loss in OVX rats during OTM. However, the OTM-induced bone loss could be recovered 3 months after OTM in OVX rats. Thus, our findings suggest that increased osteogenesis may compensate for the increased bone resorption during and after OTM and enable effective accelerated OTM in OVX rats.

Phosphorylated Peptides from Antarctic Krill (Euphausia superba) Prevent Estrogen Deficiency Induced Osteoporosis by Inhibiting Bone Resorption in Ovariectomized Rats

In the current study, we investigated the improvement of phosphorylated peptides from Antarctic krill Euphausia superba (PP-AKP) on osteoporosis in ovariectomized rats. PP-AKP was supplemented to ovariectomized Sprague-Dawley rats for 90 days. The results showed that PP-AKP treatment remarkably prevented the reduction of bone mass and improved cancellous bone structure and biochemical properties. PP-AKP also significantly decreased serum contents of tartrate-resistant acid phosphatase (TRACP), cathepsin K (Cath-k), matrix metalloproteinases-9 (MMP-9), deoxypyridinoline (DPD), C-terminal telopeptide of collagen I (CTX-1), Ca, and P. Mechanism investigation revealed that PP-AKP significantly increased the osteoprotegerin (OPG)/receptor activator of nuclear factor κB ligand (RANKL) ratio in mRNA expression, protein expression, and serum content. Further research suggested that NF-κB signaling pathways were inhibited by suppressing the mRNA and protein expressions of nuclear factor of activated T-cells (NFATc1) and tumor necrosis factor receptor-associated factor 6 (TRAF6), diminishing the mRNA expression and phosphorylation of nuclear factor κB p65 (NF-κB p65), three key transcription factors in NF-κB pathways. These results suggest that PP-AKP can improve osteoporosis by inhibiting bone resorption via suppressing the activation of osteoclastogenesis related NF-κB pathways.