Effect of Raloxifene Administration on Bone Response Around Implant in the Maxilla of Osteoporotic Rats.

OBJECTIVES: To determine the effect of raloxifene (RAL) on bone response around implants in the maxilla of osteoporotic rats. MATERIALS AND METHODS: Forty-five female rats at 8 weeks-old were divided into 3 groups: (1) control group, sham-operated rats, (2) ovariectomized group (OVX), and (3) ovariectomized and raloxifene-administered group (RAL). Eight weeks after the ovariectomy, upper right molar was extracted and an implant was placed at 4 weeks post-extraction. The RAL group was administered with 1 mg/kg/d of raloxifene via gavage while the OVX group and the control group received saline only. Three rats in each group were sacrificed at 1, 4, 7, 14, and 28 days and histologic sections were evaluated by hematoxylin and eosin staining and micro-computerized tomography was taken. RESULTS: The RAL group showed faster bone formation around the implant than the OVX group. At 4 weeks after implantation, newly formed bone close to implant threads was mature with considerable quantity of bone marrow in the RAL group. CONCLUSION: Raloxifene showed increased bone formation around implant. This might have clinical implications in prosthetic restoration by dental implants for patients with poor bone quality.

Improved Bone Regeneration With Multiporous PLGA Scaffold and BMP-2-Transduced Human Adipose-Derived Stem Cells by Cell-Permeable Peptide.

OBJECTIVE: Currently, much work has focused on the engineering of bone using adipose-derived stem cells (ADSCs), which differentiate into osteogenic cells. This study was conducted to assess the bone-regenerating capacity of ADSCs with genetic modification. MATERIALS AND METHODS: ADSCs were cultured and transduced with recombinant adenovirus-expressing bone morphogenetic protein-2 (rAd/BMP-2). Two 5-mm full-thickness bone defects were created on the parietal bones of 24 rats. The defects were left empty (n = 12), restored with a scaffold alone (n = 12), transplanted with ADSCs in osteogenic media (n = 12), or transplanted with rAd/BMP-2-transduced ADSCs (n = 12). Six defects from each group were assessed by histologic observation, histomorphometric analysis, and microcomputed tomography (micro-CT) imaging at 4 and 8 weeks after transplantation. RESULTS: Increased new bone formation was observed in the rAd/BMP-2-transduced ADSC groups, compared with the other groups. On micro-CT, significant differences were noted in bone volume-to-tissue volume ratios between rAd/BMP-2-transduced ADSCs group and the other groups at both time points (P < 0.05). CONCLUSION: The result demonstrates that transferring BMP-2 promotes the osteogenic differentiation of ADSCs and enhances bone regeneration. Under limitation of this study, genetic modification of ADSCs with BMP-2 could be adopted in clinical application.

Enhancing Effect of Intermittent Parathyroid Hormone Administration on Bone Formation After Titanium Implant Placement in an Ovariectomized Rat Maxilla.

OBJECTIVE: This study examined the effect of intermittent parathyroid hormone (PTH) administration on the bone response around implant on the maxilla of rats with ovariectomy-induced osteoporosis. MATERIAL AND METHODS: A total of 27 female Sprague-Dawley rats were divided into 3 groups (n = 9) and were ovariectomized (OVX). Eight weeks after, upper right molar was extracted and an implant was placed at 4 weeks after extraction. The PTH group received PTH, and the OVX group and the control group received vehicle only. Beginning after implant placement, 30 µg/kg of PTH was subcutaneously administered in the dorsum 3 times a week. Three rats in each group were killed at 1, 2, and 4 weeks and histologic sections were evaluated. RESULTS: After 4 weeks, the amount of newly formed bone around implants in the PTH group was comparable with the control group, with bone covering the implant surface in both groups. However, the OVX group displayed relatively small amount of new bone. CONCLUSION: Intermittent PTH has the potential to increase new bone formation around implant. These findings have clinical implications in prosthetic restoration by implants with poor bone quality.

Clinical outcomes of patients with unilateral internal derangement of the temporomandibular joint following arthrocentesis and stabilization splint therapy.

BACKGROUND: The management of internal derangement (ID) of the TMJ is challenging because of multiple etiologic factors and varying degrees of severity. The aim of this study was to evaluate the clinical outcomes of patients with unilateral ID treated with arthrocentesis and stabilization splint therapy during a 6-month period. METHODS: A total of 105 patients (87 females, 18 males) with unilateral ID were included in this study. Patients were divided into unilateral anterior disc displacement with reduction (ADDwR) and unilateral anterior disc displacement without reduction (ADDwoR). Patients with ADDwoR were subdivided according to the erosive bone changes. Objective parameters on mandibular movement and subjective parameters on pain were obtained and assessed. Their clinical outcomes before and after arthrocentesis and stabilization splint therapy were compared with the chi-square, Fisher's exact test, paired t-test, or Wilcoxon singed-rank test. RESULTS: All objective parameters of unilateral ID patients significantly increased at the 6-month follow-up. The differences in mean visual analog scale (VAS) pain scores were statistically significant in all subjective variables (p < 0.01). In joints with ADDwoR, preoperative maximal mouth opening, and maximal protrusive movement in both groups, with erosive and non-erosive changes were significantly increased after 6 months (p < 0.01). However, right and left maximal lateral movement increased after treatment in both groups but without significant differences. All VAS pain scores on jaw movement and palpation of associated muscles showed a significant decrease regardless of erosive changes. CONCLUSIONS: The combination of arthrocentesis and subsequent stabilization splint therapy was shown to be highly effective in pain reduction and improvement of mandibular movements in both unilateral ADDwR and ADDwoR, as well as in cases with both erosive and non-erosive bony changes associated with unilateral ADDwoR.

Effect of Raloxifene on Bone Formation Around Implants in the Osteoporotic Rat Maxilla: Histomorphometric and Microcomputed Tomographic Analysis.

PURPOSE: Raloxifene, an antiresorptive drug, prevents bone loss and promotes bone formation by secondary anabolic action. The purpose of this study was to investigate the effectiveness of raloxifene on the osseointegration of implants in the rat model of the osteoporotic maxilla. MATERIALS AND METHODS: Thirty Sprague-Dawley female rats aged 10 weeks were randomly assigned to the following groups: (1) raloxifene (RAL) group (n = 10), (2) ovariectomized (OVX) group (n = 10), and (3) control group (sham-operated, n = 10). Both ovaries were removed to induce osteoporosis, and the maxillary right molar was extracted. After 4 weeks, an implant was placed on the same edentulous area. Raloxifene 1 mg/kg/day was administered to the experimental animals in the RAL group, while those in the ovariectomized group and sham-operated group were given the same amount. All experimental animals were sacrificed at 4 weeks after implants were placed. Histomorphometric measurements of the bone area ratio (BA, %) and bone-to-implant contact ratio (BIC, %) around the implant were performed. Three-dimensional (3D) microcomputed tomographic (micro-CT) analysis of peri-implant bone microarchitecture was also performed and statistically analyzed. RESULTS: In the histomorphometric analysis, the BA ratio of the implant in the RAL group was higher than that in the OVX group (53.3% ± 7.2% vs 38.2% ± 11.7%, P = .024). BIC around the implant in the RAL group did not show a statistical difference compared with that in the OVX group (42.7% ± 15.0% vs 34.5% ± 16.2%, P > .05). In microstructural analysis, the RAL group showed a significant increase of trabecular thickness compared with the OVX group (0.09 ± 0.02 mm vs 0.06 ± 0.01 mm, P = .013). However, raloxifene did not show convincing differences between the groups in other micro-CT parameters (P > .05). CONCLUSION: The results show that raloxifene administration demonstrated enhanced new peri-implant bone formation in the osteoporotic rat maxilla. Further research is needed to reveal the effect of raloxifene on the clinical outcome of patients with poor bone quality who undergo dental implant treatment.

Intermittent Parathyroid Hormone Improves Bone Formation Around Titanium Implants in Osteoporotic Rat Maxillae.

PURPOSE: Parathyroid hormone (PTH) plays an important role in the treatment of osteoporosis due to its anabolic effect. In this study, PTH was administered intermittently to rats with ovariectomy-induced osteoporosis, titanium implants were placed into the rat maxillae, and the response of surrounding bone was evaluated. MATERIALS AND METHODS: A total of 30 female 8-week-old Sprague-Dawley rats were either ovariectomized to induce osteoporosis or sham operated. After 8 weeks, the upper right first molar was extracted and after a 4-week healing period an implant was placed. The animals were then divided into three groups: the PTH group (n = 10), which had been ovariectomized and received postimplant PTH; the OVX group (n = 10), which had been ovariectomized but did not receive postimplant PTH; and the control group (n = 10), which had been sham operated only (n = 10). Following implant placement, the rats in the PTH group received intermittent doses (three times a week) of PTH (30 µg/kg) subcutaneously in the dorsum. All the rats were sacrificed 4 weeks after implantation and specimens of the peri-implant maxillary bone were harvested, including the implant. Samples were evaluated by histomorphometric analysis and three-dimensional microcomputed tomography. RESULTS: Histomorphometric results showed that the mean bone area per tissue area (BA/TA) was 54.16% ± 2.2% in the PTH group and 45.24% ± 6.3% in the OVX group. The percentage of bone-to-implant contact (BIC) was 45.58% ± 9.4% in the PTH group and 32.00% ± 10.9% in the OVX group. Mean BA/TA and mean BIC values in the PTH group were higher than those in the OVX group; however, the differences were not statistically significant (P > .05). Microstructural data also showed differences between the groups. Bone volume was greater and trabecular bone was thicker in the PTH group than in the OVX group and more trabeculae were found in the PTH group. Bone mineral density was also higher in the PTH group. However, statistical analysis failed to show a significant difference between these two groups in any parameters other than trabecular thickness (P = .023). CONCLUSION: Despite the limitations of this study, intermittent PTH administration in humans may be helpful in accelerating new bone formation around implants. PTH treatment could improve clinical outcomes when dental implants are placed in jaws with low-quality bone.

Effects of alveolar bone displacement with segmental osteotomy: micro-CT and histomorphometric analysis in rats.

The purpose of this study was to evaluate the effects of segmental osteotomy on the blood vessels and osteoclasts in rats using micro-computed tomography (micro-CT) and histomorphometric analysis. After segmental osteotomy was performed around the maxillary first molars of 36 male Sprague-Dawley rats (n = 72), the samples were divided into a control group (no displacement), 0.5 D group (0.5 mm buccal displacement) and 1.0 D group (1.0 mm buccal displacement) (n = 24/group). At 1, 2, 4 and 8 weeks after surgery, changes in the blood vessel volume were investigated using micro-CT with perfusion of radiopaque silicone rubber. Tartrate-resistant acid phosphatase (TRAP) staining was used for histomorphometric analysis. Two-way repeated measures analysis of variance (rmANOVA) was performed to compare the volume of blood vessels and number of TRAP-positive osteoclasts among the groups. Regarding blood vessel volume, the displacement groups had no significant effects, while the time points had significant effects (p = 0.014). The blood vessel volume at 1 week was significantly smaller than that at 2, 4, and 8 weeks (p = 0.004, p = 0.026, and p = 0.005, respectively). Regarding TRAP cell count, the displacement groups had no significant effects, while the time points had significant effects (p < 0.001). The number of TRAP-positive osteoclasts at 8 weeks was significantly smaller than that at 1, 2, and 4 weeks (p < 0.001, p < 0.001, and p = 0.002, respectively), and the count at 4 weeks was smaller than that at 1 week (p = 0.011). Therefore, a regional osteoclast-related acceleratory phenomenon was maintained until 4 weeks after surgery.

Effects of alveolar bone displacement with segmental osteotomy: micro-CT and histomorphometric analysis in rats

Abstract The purpose of this study was to evaluate the effects of segmental osteotomy on the blood vessels and osteoclasts in rats using micro-computed tomography (micro-CT) and histomorphometric analysis. After segmental osteotomy was performed around the maxillary first molars of 36 male Sprague-Dawley rats (n = 72), the samples were divided into a control group (no displacement), 0.5 D group (0.5 mm buccal displacement) and 1.0 D group (1.0 mm buccal displacement) (n = 24/group). At 1, 2, 4 and 8 weeks after surgery, changes in the blood vessel volume were investigated using micro-CT with perfusion of radiopaque silicone rubber. Tartrate-resistant acid phosphatase (TRAP) staining was used for histomorphometric analysis. Two-way repeated measures analysis of variance (rmANOVA) was performed to compare the volume of blood vessels and number of TRAP-positive osteoclasts among the groups. Regarding blood vessel volume, the displacement groups had no significant effects, while the time points had significant effects (p = 0.014). The blood vessel volume at 1 week was significantly smaller than that at 2, 4, and 8 weeks (p = 0.004, p = 0.026, and p = 0.005, respectively). Regarding TRAP cell count, the displacement groups had no significant effects, while the time points had significant effects (p < 0.001). The number of TRAP-positive osteoclasts at 8 weeks was significantly smaller than that at 1, 2, and 4 weeks (p < 0.001, p < 0.001, and p = 0.002, respectively), and the count at 4 weeks was smaller than that at 1 week (p = 0.011). Therefore, a regional osteoclast-related acceleratory phenomenon was maintained until 4 weeks after surgery.