Combining bisphosphonates with allograft bone for implant fixation

Clinical values of serum Semaphorin 4D (Sema4D) in medication‑related osteonecrosis of the jaw

BACKGROUND

Bisphosphonates (BPs) are widely used in clinical practice to prevent and treat bone metabolism-related diseases. Medication-related osteonecrosis of the jaw (MRONJ) is one of the major sequelae of BPs use. Early prediction and intervention of MRONJ are of great significance.

METHODS

Ninety-seven patients currently on treatment with BPs or with a history of BPs usage and 45 healthy volunteers undergoing dentoalveolar surgery were included in this study. Participants' serum Semaphorin 4D (Sema4D) levels were measured and analyzed before participants underwent surgery (T0) and after a 12-month follow-up (T1). Kruskal-Wallis test and ROC analysis were used to examine the predictive effect of Sema4D on MRONJ.

RESULTS

Sema4D levels in serum of patients corresponding to confirmed MRONJ were significantly lower at both T0 and T1 time points compared to non-MRONJ and healthy controls. Sema4D has a statistically predictive effect on the occurrence and diagnosis of MRONJ. Serum Sema4D levels were significantly reduced in MRONJ class 3 patients. MRONJ patients who received intravenous BPs had significantly lower Sema4D levels than those who received oral BPs.

CONCLUSION

Serum Sema4D level has predictive value for the onset of MRONJ in BPs users within 12 weeks after dentoalveolar surgery.

Effects of local application of alendronate on early healing of extraction socket in dogs

OBJECTIVE

The aim of the present study was to assess the effects of alendronate (ALN) on bone remodeling following tooth extraction in a dog model.

MATERIAL AND METHODS

For the study, fifteen male Beagles dogs of approximately 12 months of age were used. Mesial roots of four mandibular premolars were endodontically treated, and the distal roots were removed. ALN concentrations of 0.5, 1, and 2 mg/mL were topically applied for 15 min, while a sterile saline was used as a negative control. After the healing period of 1, 2, and 8 weeks, the samples were analyzed by micro-CT and histology.

RESULTS

Treatment with ALN increased vertical distance between the lingual and the buccal crestal bones. While the ALN-treated sockets had preserved more lingual bone areas, control sockets showed better preservation of the buccal bone areas. ALN treatment resulted in more osteoid formation within the extraction sockets compared with the control. Higher bone volume was found in ALN groups than in the control at 2-week and 8-week healing periods, reaching the significant difference only for the extraction sockets pooled for the ALN treatment.

CONCLUSIONS

Although ALN treatment could not prevent buccal bone resorption following tooth extraction in dogs, it proved beneficial for the preservation of the lingual bone and formation of new bone within the socket. There was no clear relation between the ALN dosages and the alterations within the extraction sockets.

CLINICAL RELEVANCE

ALN affects bone remodeling of the extraction socket. The optimal concentration remains to be determined in future studies.

Immediate implant placement following 1-year treatment with oral versus intravenous bisphosphonates: a histomorphometric canine study on peri-implant bone

OBJECTIVES

Bisphosphonates (BPs) are anti-resorptive medications with inhibitory effects on osteoclasts which decrease bone turnover. The present study aimed to assess the early effects of BPs on peri-implant bone.

MATERIALS AND METHODS

Twelve female mongrel dogs were assigned to one control and two experimental groups as follows: 12 months of oral alendronate (ALN, 3.5 mg/kg/week) or intravenous (IV) pamidronate (PAM, 1 mg/kg/week) for experimental groups. Following 8 weeks after implant insertion, the specimens were sacrificed, histological evaluation was performed, and C-terminal telopeptide of collagen I (CTx) analysis was performed on serums.

RESULTS

PAM demonstrated the greatest marginal bone level (MBL), 2.64 ± 0.48, followed by ALN and control, 2.5 ± 0.4 and 0.66 ± 0.5 respectively. The least bone-implant contact was observed in PAM group (%39 ± 0.03) while it was significantly greater in the control group (p < 0.05). PAM and ALN demonstrated < 10 CTx levels versus > 300 in controls.

CONCLUSION

It is assumed that long-term oral or IV BP therapy decreases marginal bone resorption and osseointegration. These changes were more accentuated in IV BP administration. CTx does not seem to be a precise predictor for bisphosphonate-related osteonecrosis of the jaw.

CLINICAL RELEVANCE

BPs impair peri-implant bone remodeling and this phenomena may be effective for reducing resorption at esthetic zone implants; however, decrease in osseointegration may be a concern for implant treatment in patients receiving BPs.

Pretreatment with Bisphosphonate Enhances Osteogenesis of Bone Marrow Mesenchymal Stem Cells

Mesenchymal stem cell (MSC)-mediated bone regeneration is used to replace lost bone. However, methods to accelerate the process and stabilize regenerated bone remain limited. Therefore, we investigated the effect of bisphosphonates (BPs) on the function of bone marrow mesenchymal stem cells (BMMSCs) to determine if they might enhance MSC-mediated bone regeneration. We isolated and cultured BMMSCs from BALB/c mice and treated the cells with 0.1, 0.5, 1, 5, or 10 μM zoledronic acid (ZA; Zometa, a commercially available BP). ZA had a dose-dependent effect on BMMSCs proliferation and osteogenesis. ZA at concentrations of 5 and 10 μM inhibited the proliferation and osteogenic differentiation of BMMSCs. By contrast, in addition to inducing the proliferation and osteogenesis of BMMSCs, 0.5 μM ZA upregulated expressions of the osteogenesis-related genes Alp, osterix (Osx), and bone sialoprotein (Bsp) and enhanced osteogenesis in vivo when ZA-treated BMMSCs were implanted subcutaneously in nude mice. In addition, 0.5 μM ZA increased expression of Opg in BMMSCs, decreased the Rankl/Opg ratio, and decreased the number of osteoclasts. However, it was not associated with adverse effects on numbers of regulatory T cells or levels of Th17, transforming growth factor-β1 (TGF-β1), and interleukin-17a (IL-17a) when cocultured with T cells. In conclusion, 0.5 μM ZA pretreatment enhanced the proliferation and osteogenesis of BMMSCs in vitro and in vivo and decreased the number of osteoclasts without impairment of BMMSCs immunomodulatory properties. In vitro pretreatment of BMMSCs with BP and subsequent implantation may be a safe and effective way of enhancing MSC-mediated bone regeneration.