The Effects of Zoledronic Acid on Mandibular Fracture Healing in an Osteoporotic Model

Effects of a single intravaneous dose of zoledronic acid on bone healing following tooth extraction in ovariectomized rabbits

Objective

The present study is aimed to investigate the effects of administering a single intravenous dose of zoledronic acid (ZA) on bone healing following tooth extraction in ovariectomized rabbits.

Materials and methods

Female, New Zealand rabbits were randomly divided into three groups including Control, ovariectomy + saline (OVX) and ovariectomy + zoledronic acid group (ZOL). Bilateral ovariectomy was performed to the rabbits in OVX and ZOL groups under general anesthesia. Control group underwent sham surgery. Eight weeks later, mandibular right incisors of all animals were extracted under general anesthesia. Before the procedure, Control and OVX groups were given saline and 0.1 mg/kg ZA was administered to ZOL group intravenously. All animals were sacrificed after 12 weeks.

Results

The findings of histopathological and biochemical evaluations reflected insignificant differences among study groups in vascular endothelial growth factor (VEGF), increases in osteoclasts, ossification, vascularization and mononuclear cell infiltration measures (p > 0.05). In contrast, bone morphogenic protein 2 (BMP-2), tumor necrosis factor alpha (TNF-α) and organization of the extraction wound differed significantly between groups (p < 0.05)

Conclusion

The potential beneficial effects of ZA administration on the wound healing process following tooth extraction were demonstrated via serum TNF-α, BMP-2 and VEGF levels in an osteoporotic model in ovariectomized rabbits.

Effect of low-level laser therapy and zoledronic acid on bone repair process

This study aimed to evaluate, through histomorphometric analysis, the bone repair process in the tibia of rats treated with zoledronic acid and submitted to 808-nm low-level laser therapy (LLLT) by using arsenide aluminum gallium laser. For this purpose, 20 rats were used and distributed according to treatment: group 1-saline administration; group 2-treated with LLLT; group 3-treated with zoledronic acid; and group 4-treated with zoledronic acid and LLLT. The zoledronic acid was administered at a dose of 0.035 mg/kg every 2 weeks for 8 weeks. Subsequently, bone defects of 2 mm were prepared in the tibias of all groups. The bone defects in groups 2 and 4 were irradiated with LLLT in the immediate post-operative period. After 14 and 28 days of application, the animals were submitted and euthanized for histomorphometric analysis. The results were submitted to statistical analysis (α = 5%), and the intragroup comparison was performed using the t test. On the other hand, for intergroup comparison, the ANOVA test was performed, and to the groups presenting statistically significant difference, the Student-Newman-Keuls test was used. In intergroup comparison, group 1 (mean ± SD= 45.2 ± 18.56%) showed a lower bone formation compared with groups 2 (64.13 ± 3.51%) (p = 0.358) and 4 (15.2 ± 78.22%) (p = 0.049), at the 14-day period. Group 3 (20.99 ± 7.42%) also presented a lower amount of neoformed bone tissue, with statistically significant difference when compared with groups 1 (p = 0.002), 2, and 4 (p ≤ 0,001). After 28 days, group 1 presented a lower amount of neoformed bone tissue compared with the other groups, with p = 0.020. Thus, it was concluded that LLLT associated with zoledronic acid is effective for stimulating bone formation in surgically created defects in rats, at the periods studied.

Case report of maxillofacial fracture in a patient under bisphosphonates in the absence of ONJ disease: Guidelines?

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Case consisting of traumatic fracture in patient under bisphosphonates.

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No MRONJ, so no pathological fracture.

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No guidelines available for patients ‘at risk’.

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Best treatment avoids periosteal stripping.

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Fixation using external fixation or locking reconstruction plate.

Introduction

Inspired by the presented case, this paper investigates treatment options for patients under active bisphosphonate therapy, suffering from a traumatic fracture in the absence of MRONJ (patients classified as ‘at risk’). We review literature in search of standardized protocols and in combination.

Presentation of case

A 75-year-old woman, suffering from osteoporosis for over a decade and being treated with alendronate for about 10 years, stumbled and fell and ended up with a displaced fracture on the right side of her extremely atrophied mandible. Under general anesthesia, using a limited submandibular approach with minimal reflecting of the periosteum, an external fixation device was placed. The patient recovered well from surgery and was discharged after 2 days. Long term follow-up shows good healing with a mouth opening of 46 mm in the absence of any sensory of functional deficits.

Discussion

We conclude from our literature review that there are no clear guidelines regarding fixation of traumatic (non-pathologic) maxillofacial fractures in patients under active antiresorptive therapy. Literature suggests that damaging the periosteum needs to be avoided since this would endanger the already fragile blood supply in the area. This could make an intra-oral approach unfavourable.

Conclusion

We prefer an extra-oral approach whenever possible. The choice between the use of supraperiostally placed locking reconstruction plates or external fixation should be based on the overall medical condition of the patient, the regional osseous anatomy and the specific fracture morphology.

The effect of infliximab on bone healing in osteoporotic rats

Purpose:

The aim of this study was to evaluate the effect of the infliximab on autogenous-mediated bone regeneration and resorption of autogenous graft in the ovariectomised rat model.

Materials and methods:

Forty rats underwent ovariectomy and 6 weeks later the animals were randomly assigned to four groups. Critical size defects were created in each rat calvarium. In the control group (C), the flap was closed without any further action. In the only infliximab group (In), the flap was closed without any further action. After the operation, intravenous infliximab was injected. In the autogenous graft group (Ag), autogenous bone was applied in to the defect. In autogenous graft + infliximab group (Ag+In), autogenous graft was placed on the defect. After the operation, intravenous infliximab was injected. The animals were sacrificed at 4 weeks. Bone formation was assessed by micro-computed tomography (micro-CT) scans and stereological analysis.

Results:

The mean new bone volume was the greatest in Ag+In group (1.76 ± 0.20), followed by the Ag group (1.51 ± 0.05) (statistically significant difference at P <0.05). The lowest new bone was found in the control group (1.05 ± 0.09), however no difference was observed from the In group (1.14 ± 0.08) ( P >0.05). Besides there was a statistically significant difference between the Ag+In group (1.00 ± 0.05) and Ag group (0.74 ± 0.04) in terms of the graft volume ( P <0.05).

Conclusion:

This study, despite its limitations, showed that infliximab has a beneficial effect for prevent graft resorption and bone regeneration in osteoporotic rats.

Effects of low-level laser therapy on changes in inflammation and in the activity of osteoblasts in the expanded premaxillary suture in an ovariectomized rat model

BACKGROUND AND OBJECTIVE

Osteoporosis is a progressive systemic skeletal disease characterized by reduced bone mass/density and microarchitectural deterioration of bone tissue. Bone formation initially exceeds bone resorption, but by the third decade, such formation is reversed, resulting in a net loss of bone mass. This resorption, in turn, increases bone fragility and susceptibility to fracture. This study aimed to evaluate the effects of low-level laser therapy (LLLT) on bone regeneration in the expanded premaxillary suture in an ovariectomized rat model.

METHODS

Thirty-two 12-week-old female Wistar albino rats were used in the experiment. All of the animals underwent ovariectomy 3 months before the experiment. Expansion appliances were affixed to the maxillary incisors for the expansion of premaxillary sutures. The premaxillary sutures of the laser group were exposed to 5 J/cm(2) laser energy, and no treatment was performed for the controls. All the rats in both groups were euthanized on either the 7th day (n=8) [end of expansion period; Laser Group 1(LG1) and Control Group 1 (CG1)] or the 17th day (n=8) [end of retention period; Laser Group 2 (LG2) and Control Group 2 (CG2)], respectively, for histological assessment.

RESULTS

Histological findings indicated that the LG1 group showed a significantly higher number of osteoblasts than did the CG1 group (p=0.028). The CG1 and CG2 groups showed a significantly higher number of osteoclasts than did the LG1 and LG2 groups, respectively (p=0.005), (p=0.032). The LG2 group exhibited a capillary increase similar to that of the other groups, without statistically significant differences.

CONCLUSIONS

On the basis of our methodology and results, we conclude that low-level laser associated with rapid maxillary expansion influences bone regeneration in sutures, thereby accelerating healing, even in ovariectomized rats. We found that LLLT decreased osteoclastic activity in the ovariectomized rats. Therefore, preventing osteoporosis necessitates further investigations to clarify the effect of LLLT on postmenopausal patients.

Prophylactic Effects of Propranolol versus the Standard Therapy on a New Model of Disuse Osteoporosis in Rats

Disuse by bed rest, limb immobilization, or space flight causes rapid bone loss by arresting bone formation and accelerating bone resorption. Propranolol (a non-selective β-adrenergic antagonist) has been shown to improve bone properties by increasing bone formation and decreasing bone resorption in an ovariectomy-induced rat model. However, no studies have yet compared the osteoprotective properties of propranolol with well-accepted therapeutic interventions for the treatment and prevention of immobilization/disuse osteoporosis. To clarify this, we investigated the effects of propranolol compared with zoledronic acid and alfacalcidol in a new animal model of immobilization/disuse osteoporosis. Three-month-old male Wistar rats were divided into five groups with six animals in each group: (1) immobilized (IMM) control; (2) normal control; (3) IMM + zoledronic acid (50 μg/kg, intravenous single dose); (4) IMM + alfacalcidol (0.5 μg/kg, per oral daily); (5) IMM + propranolol (0.1 mg/kg, subcutaneously 5 days/week) for 10 weeks. In groups 1 and 3-5, the right hindlimb was immobilized. At the end of treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and cortical microarchitecture. Treatment with propranolol induced greater reductions in the bone porosity of the right femur and improved the mechanical properties of the femoral mid-shaft femur in comparison to the IMM control. Moreover, treatment with propranolol also improved the microarchitecture of cortical bones when compared with the IMM control, as indicated by scanning electron microscopy. The anti-osteoporotic property of propranolol was comparable with zoledronic acid and alfacalcidol. This study shows that the bone resorption induced by immobilization/disuse in rats can be suppressed by treatment with propranolol.