Enhancement of peri-implant bone formation via parathyroid hormone administration in a rat model at risk for medication-related osteonecrosis of the jaw

Purpose@#Dental implant-associated medication-related osteonecrosis of the jaw has been frequently reported in patients administered bisphosphonates (BPs) to prevent osteoporosis. The aim of this study was to investigate the effect of intermittent administration of parathyroid hormone (PTH) on peri-implant bone in the maxillae of ovariectomized rats systemically administered BPs. @*Methods@#Thirty 8-week-old female Sprague-Dawley rats were randomly divided into 3 groups. The OVX-ZP group included ovariectomized rats administered 60 μg/kg of zoledronate once a week for 6 weeks and 30 μg/kg PTH after implant installation. The OVX-Z group included ovariectomized rats administered 60 μg/kg of zoledronate once a week for 6 weeks and saline after implant installation, and the control group included rats that underwent a sham operation and were then administered saline. Rats were sacrificed 4 weeks after implant placement for histomorphometric and micro-computed tomography (CT) analyses. @*Results@#The average bone area percentage was greater in the OVX-ZP group than in the OVX-Z group (53.4%±4.0% vs. 28.9%±9.5%, P=0.01). The bone-to-implant contact ratio was 50.8%±1.4% in the OVX-ZP group and 16.9%±2.4% in the OVX-Z group (P=0.012). The average bone volume ratio as shown on micro-CT was 31.3%±19.8% in the OVX-ZP group and 19.4%±9.3% in the OVX-Z group (P=0.045). The OVX-ZP and OVX-Z groups displayed similar trabecular thickness (0.06±0.004 mm vs. 0.06±0.002 mm) (P>0.05) and trabecular separation (0.21±0.02 mm vs. 0.29±0.13 mm) (P>0.05). However, the number of trabeculae in the OVX-ZP group was significantly higher than that in the OVX-Z group (4.3±1.33/mm3 vs. 2.2±0.19/mm3) (P=0.024). @*Conclusions@#The present findings indicate that intermittently-administered PTH can promote peri-implant bone formation and suggest that PTH administration may aid in effective treatment for medication-related osteonecrosis of the jaw after dental implantation.

Effect of Intermittent Parathyroid Hormone Administration on the Microstructure of Jaw Bone in the Ovariectomized Rats

PURPOSE: Parathyroid hormone (PTH) therapy has drawn attention, as an alternative to anti-resorptive drugs since PTH accelerates bone density by anabolic action. The purpose of this study was to identify the effect of intermittent PTH administration on jaw bones of rat undergone bilateral ovariectomy. MATERIALS AND METHODS: Nine female Sprague-Dawley rats were divided into three groups. PTH group was ovariectomized (OVX) to induce osteoporosis and PTH 30 microg/kg was administered 1 week after the surgery. In OVX group, ovariectomy was performed and only vehicle was administered by subcutaneous injection 3 times per week. Control group was subjected to sham surgery. The animals were sacrificed 8 weeks after the surgery and specimens were obtained from ilium and upper and lower jaw bones. Histological investigation was carried out by using an optical microscope and micro-computed tomography was taken to examine structural property changes in each bone sample. RESULT: In the ilium, the bone volume ratio (bone volume/total volume, BV/TV) of PTH, OVX and control groups was 53.75%+/-7.57%, 50.61%+/-12.89%, 76.20%+/-5.92% (P=0.061) and bone mineral density (BMD) was 1.12+/-0.09, 0.88+/-0.48, 1.38+/-0.07 g/cm3 (P=0.061). In the mandible, BV/TV of PTH, OVX and control groups was 64.60%+/-12.17%, 58.26%+/-9.63%, 67.54%+/-14.74% (P=0.670) and BMD was 1.21+/-0.17, 1.19+/-0.13, 1.27+/-0.18 g/cm3 (P=0.587). In the maxilla, BV/TV of PTH, OVX and control groups was 61.19%+/-8.92%, 52.50%+/-11.22%, 64.60%+/-12.17% (P=0.430) and BMD was 1.20+/-0.11, 1.11+/-0.16, 1.21+/-0.17 g/cm3 (P=0.561). No statistically significant difference was found in any variables in all groups. Histological observation revealed that the ilium in OVX group demonstrated sparsely formed trabecular bones compared with other groups. However, upper and lower trabecular bones did not present significant differences. CONCLUSION: Intermittent administration of PTH appears to affect the microstructure of rat jaw bones, but statistical significance was not found. However, the measurements in this study partly implicated the possible anabolic effect of PTH in vivo.

Biological markers around immediately placed titanium implant in the extraction socket of diabetic and insulin-treated rat maxilla

OBJECTIVES: Dental implants installation in patients with diabetes remains controversial as altered bone healing around implants has been reported. And little is known about the biological factors involved in bone healing around implants. The present study aimed to investigate the biological markers around immediately placed implants in rats with controlled and uncontrolled diabetes. MATERIALS AND METHODS: Twenty rats (40 sites) were divided into the control, insulin-treated and diabetic groups. The rats received streptozotocin (60 mg/kg) to induce diabetes; animals in the insulin-treated group also received three units of subcutaneous slow-release insulin. Two threaded titanium alloy implant (1.2x3 mm) were placed in the extraction socket of the both maxillary first molars and allowed for healing. Bone blocks including implant were harvested at 3 days, 1, 2 and 4 weeks. The levels of bone morphogenetic protein (BMP)-4, transforming growth factor (TGF)-beta1, osteocalcin (OC) and osteonectin (ON) were measured in the peri-implant osseous samples by RT-PCR. RESULTS: The BMP-4 level increased immediately in all groups by day 3, then decreased abruptly in the control and the insulin-treated groups. However, by week 4, all groups showed mostly the same amount of BMP-4 expression. The level of TGF-beta1 also instantly increased by day 3 in the insulin-treated group. This level elevated again reaching the same values as the control group by week 4, but was not as high as the diabetic group. In addition, the expression of OC and ON in the control and insulin-treated groups was higher than that of the diabetic group at 2 weeks and 4 weeks, indicating active bone formation in these groups. CONCLUSION: The immediate placement of titanium implants in the maxilla of diabetic rat led to an unwanted bone healing response. Conclusively, the results of this study suggest that immediate implant insertion in patients with poorly controlled diabetes might be contraindicated.

Bone response around immediately placed titanium implant in the extraction socket of diabetic and insulin-treated rat maxilla

INTRODUCTION: Dental implants are used routinely with high success rates in generally healthy individuals. By contrast, their use in patients with diabetes mellitus is controversial because altered bone healing around implants has been reported. This study examined the bone healing response around titanium implants placed immediately in rats with controlled and uncontrolled diabetes. MATERIALS AND METHODS: Twenty rats were divided into the control, insulin-treated and diabetic groups. The rats received streptozotocin (60 mg/kg) to induce diabetes; animals in the insulin-treated group also received three units of subcutaneous slow-release insulin. A titanium implant (1.2x3 mm) was placed in the extraction socket of the maxillary first molar and bone block was harvested at 1, 2 and 4 weeks. RESULTS: Bone formation around the implants was consistently (from 1 to 4 week post-implantation) slower for the diabetic group than the control and insulin-treated group. Bone morphogenesis in the diabetic rats was characterized by fragmented bone tissues and extensive soft tissue intervention. CONCLUSION: The immediate placement of titanium implants in the maxilla of diabetic rats led to an unwanted bone healing response. These results suggest that immediate implant insertion in patients with poorly controlled diabetes might be contraindicated.

Expression of BMP4, BMP6 following sinus elevation with DBBP in rabbit

0.05). 2. The expression of BMP6 increased at postoperative 1 and 3 days in both DBBP group and AGS group. In AGS group, it decreased at postoperative 5 days, increased again at postoperative 7 days, and decreased at postoperative 9 days. In DBBP group, it increased until postoperative 7 days and decreased at postoperative 9 days. Although the expression of BMP6 was higher in AGS group compared with DBBP group, it was not statistically significant (p>0.05). 3. There was no statistically significant difference in BMP expression in both groups during same period of time. It's probably because DBBP and AGS both functioned as a space retainer so that the BMP expression in blood clot seemed to be similar. 4. Thus, DBBP would not offer many benefits for early bone regeneration compared with AGS. The expression of BMP in early bone formation seems to be more influenced by physical carrier rather than the graft type.

Two part mini-implant as an efficient tool for intermaxillary fixation

Recurrent chondroblastoma on the right temporal area : a case report