PTH(1-34)对兔骨质疏松种植体骨结合影响的研究

目的:研究甲状旁腺素1-34[PTH(1-34)]对骨质疏松动物模型中种植体周围皮质骨初期固位的影响,为今后相关实验研究及临床应用提供依据。方法:24只日本大耳白兔,随机均分为3组,2组去卵巢法制骨质疏松模型,3个月后,于胫骨近心端植入2.5 mm直径直型种植体。随机选出骨质疏松的一组作为实验组,术后每周3 d,背部皮下注射PTH(1-34),60 g/kg,其余2组背部皮下注射等量生理盐水,分别作为空白对照组和假去势组。分别于术后4周和8周处死各组一半动物,进行力学及组织形态学观察。结果:在力学实验中,无论4周或8周,实验组的最大拔出力显著高于其他2组,空白对照组稍高于假去势组,但无显著差异。组织学观察发现:4周时实验组种植体周围新生骨疏松多孔,骨小梁沿种植体壁向根端延伸,靠近种植体的骨小梁平行于种植体表面,排列紧密,小梁间连接较多;8周时实验组种植体周围骨组织量较4周时明显增加,骨小梁增粗,间隙减小。其他2组没有观察到这种现象。结论:皮下间断注射PTH(1-34)可以显著提高骨质疏松状态下种植体在皮质骨中的骨结合效果。     

Effects of bisphosphonate on bone reaction after placement of titanium implants in tibiae of ovariectomized rats

PURPOSE: This study was undertaken to investigate the action of bisphosphonate on bone reactions after the placement of titanium screw implants into the tibiae of ovariectomized rats. MATERIALS AND METHODS: Twelve-week-old female Wistar rats were divided into 4 groups of 18 animals each. The first group (Sham) was sham-operated, the second group (OVX) was ovariectomized only, the third group (Estrogen) was ovariectomized and received continuous estrogen with a 17beta-estradiol pellet, and the fourth group (YM-175) was ovariectomized and received bisphosphonate at a dose of 10 microg/kg of body weight. Titanium screw implants were placed in the proximal metaphyses of the tibiae 168 days after surgery. The animals were sacrificed 7, 14, and 56 days after implant placement. Undecalcified sections were prepared and evaluated by light microscopy. Histomorphometric measurements were obtained with a computer-based image analyzer to quantify the unit bone mass around the implant and the rate of implant-bone contact. RESULTS: Ovariectomies significantly reduced implant-bone contact and the bone volume around the implants. However, in the YM-175 group, only slight differences in both bone contact and bone volume were noted compared with the Sham and Estrogen group. The woven structure of new bone in the YM-175 group was also replaced by mature lamellar bone, as in the other groups. DISCUSSION AND CONCLUSION: These results suggested that bisphosphonate preserved the implant-bone contact and bone volume around the implants.     

Effect of intermittent PTH administration in the periodontitis-associated bone loss in ovariectomized rats

OBJECTIVE: Parathyroid hormone intermittent administration has been considered to treat bone mass decrease in osteoporotic individuals. The present study evaluates whether PTH can affect alveolar bone loss in ovariectomized rats, since estrogen deficiency has been proposed as a risk factor for periodontal disease. DESIGN AND METHODS: Thirty female rats were set in groups: ovariectomized (Ovx) and Sham operated. Ovx were divided in two groups: Ovx-PTH (1-34) treated and Ovx, which received vehicle. After 1 week, cotton ligature was placed around one lower first molar of all animals to induce periodontal disease. Ovx treated received PTH doses of 40 microg/kg, three times a week for 30 days. After that, the animals were sacrificed, the mandibles extracted, X-rayed and samples prepared for histological evaluation. Histomorphometry was performed using image analyzer software. Scanning electron microscopy (SEM) of the tibias was also performed in all animals to evaluate possible changes in bone structure caused by the estrogen deficiency. Optical densities of the radiographs were measured by aluminum step-wedge equivalent thickness. RESULTS: Histomorphomery indicated the anabolic PTH effect in ovariectomized rats with significant inhibition of periodontitis manifestation (p<0.05) thus neutralizing the periodontitis inductor effects. The photo densitometry showed a lower mandibular optical density in the ovariectomized group that did not receive PTH (p<0.05). SEM image confirmed the early effect of estrogen deficiency in osseous tissue and PTH anabolic effect. CONCLUSION: PTH systemic intermittent administration was able to reduce alveolar bone loss in ovariectomized rats, despite the presence of a periodontal disease inductor and estrogen deficiency.     

雌激素对骨质疏松时种植体骨愈合的影响:Ⅱ骨计量学和电镜观察

目的 :研究雌激素替代治疗对骨质疏松时种植体骨愈合的影响。方法 :选用32周龄雌性SD大鼠36只 ,并随机分为假手术组、卵巢切除组及雌激素组。卵巢切除12周后于大鼠胫骨近中干骺端植入纯钛螺纹状种植体 ,雌激素组同时肌注苯甲酸雌二醇。种植术后4周及12周分两批处死大鼠 ,摘取胫骨 ;标本分别进行扫描电镜观察和骨计量学测量。结果 :在种植后4周及12周时 ,雌激素组除12周时皮质骨结合率与卵巢切除组无显著差异外 ,其它各项骨计量学参数均显著高于卵巢切除组 (P<0.05或P<0.01) ;而与假手术组比较 ,除骨矿化速度及4周时单位骨量外 ,其他各项指标均无显著差异 (P>0.05)。电镜观察种植体—骨界面愈合雌激素组和假手术组均优于卵巢切除组。结论 :雌激素替代治疗可促进实验性骨质疏松大鼠种植体骨愈合 ;该方法有助于增加临床绝经性骨质疏松患者牙种植体骨整合率     

Effect of ovariectomy on bone remodeling adjacent to hydroxyapatite-coated implants in the tibia of mature rats.

PURPOSE: The purpose of this study was to examine the effects of estrogen deficiency on bone remodeling adjacent to implants in the tibia of mature rats. MATERIALS AND METHODS: Hydroxyapatite-coated implants were placed bilaterally in the proximal metaphysis of the tibia of 18 female Wistar rats (48 weeks old), and ovariectomy was performed 168 days later. As a control, sham ovariectomy was performed in a similar group of 18 rats. Six animals from each group were killed at 28, 84, and 168 days after ovariectomy. Undecalcified sections were prepared, and changes in the bone tissue around the implants were evaluated histologically. Histomorphometric measurements were made with a computer-based image analyzer to quantify the unit bone mass around each implant and the amount of implant-bone contact. RESULTS: In the cortical bone area, ovariectomy induced only a slight decrease in bone contact with the implant, compared with that in the sham-operated rats. However, both the bone volume around the implant and implant-bone contact were significantly decreased in the cancellous bone area in ovariectomized rats compared with the sham-operated rats. CONCLUSION: Thinning of the bone trabeculae holding dental implants may occur with estrogen deficiency.     

Bone reactions to titanium screw implants in ovariectomized animals

OBJECTIVE: The purpose of this study was to investigate the reactions of bone tissue after the placement of implants into the tibiae of osteopenic model rats. STUDY DESIGN: Commercially pure titanium screw implants were placed in the bilateral proximal tibial metaphyses 168 days after ovariectomy had been performed on 12-week-old female Wistar rats. For control purposes, implants were similarly placed in sham-ovariectomy rats. The healing process was examined histologically by means of undecalcified sections at various intervals from 7 to 168 days after implantation. Through use of an automated imaging analytic system, changes in relative bone mass and implant-bone contact were histomorphometrically evaluated. RESULTS: In the cortical bone area, only a slight difference in bone contact was noted with the implant until 28 days after implantation. However, ovariectomy significantly affected bone contact at 56 days after implantation. The rate of bone contact in the cancellous bone area and the relative bone mass around the implant were significantly lower in the test group than in the control group. CONCLUSIONS: It is considered that a decrease in bone mass causes a reduction in the contact area between implant and bone and may also cause a reduction in the supporting ability of the implant because of thinning of the surrounding bone tissue.     

Alendronate therapy may be effective in the prevention of bone loss around titanium implants inserted in estrogen-deficient rats

BACKGROUND: This study evaluated whether alendronate (ALD) influences bone healing around titanium implants inserted in ovariectomized rats and whether it provides a residual effect after its withdrawal. METHODS: Bilateral ovariectomies were performed in 87 Wistar rats and one screw-shaped titanium implant was placed in the tibiae. The animals were divided into the following groups: group SHAM (N = 15): sham surgeries; group OVX (N = 15): ovariectomy; group AT (N = 15): OVX plus alendronate administration for 80 days; group AW (N = 14): OVX plus alendronate administration for 40 days; group ET (N = 14): OVX plus 17beta estradiol administration for 80 days; or group EW (N = 14): OVX plus 17beta estradiol administration for 40 days. Bone-to-implant contact (BIC), bone area (BA) within the limits of implant threads, and bone density in a 500 microm-wide zone lateral to the implant (BD) were obtained and measured for the cortical (zone A) and cancellous (zone B) regions. RESULTS: In zone A, data analysis showed no significant differences among the groups regarding BIC and BD (P >0.05), and a slight beneficial effect of estradiol on BA when compared with the OVX, EW, and AW groups (P <0.05). In zone B, OVX negatively impacted bone healing around the implants, resulting in reduced BA and BD (P<0.05). ALD (continuous/interrupted) and estradiol (only continuous) positively affected BIC, BA, and BD, resulting in values at the same level as the control group (SHAM). CONCLUSIONS: ALD may prevent the negative influence of estrogen deficiency on bone healing around titanium implants inserted in OVX rats. This positive effect, in contrast to estradiol, is sustained following its withdrawal.     

Effects of Simvastatin on bone healing around titanium implants in osteoporotic rats

Objectives: Osteoporosis is known to impair the process of implant osseointegration. The recent discovery that statins (HMG‐CoA reductase inhibitors) act as bone anabolic agents suggests that statins can be used as potential agents in the treatment of osteoporosis. Therefore, we hypothesized that statins will promote osteogenesis around titanium implants in subjects with osteoporosis. Material and methods: Fifty‐four female Sprague Dawley rats, aged 3 months old, were randomly divided into three groups: Sham‐operated group (SHAM; n=18), ovariectomized group (OVX; n=18), and ovariectomized with Simvastatin treatment group (OVX+SIM; n=18). Fifty‐six days after being ovariectomized (OVX), screw‐shaped titanium implants were inserted into the tibiae. Simvastatin was administered orally at 5 mg/kg each day after the placement of the implant in the OVX+SIM group. The animals were sacrificed at either 28 or 84 days after implantation and the undecalcified tissue sections were obtained. Bone‐to‐implant contact (BIC) and bone area (BA) within the limits of implant threads were measured around the cortical (zone A) and cancellous (zone B) bone regions. Furthermore, bone density (BD) of zone B in a 500 μm wide zone lateral to the implants was also measured. Results: There were no significant differences in BIC and BA measurements in zone A in any of the three groups at either 28 or 84 days after implantation (P>0.05). By contrast, in zone B, significant differences in the measurement of BIC, BA, and BD were observed at 28 and 84 days between all three groups. Bone healing decreased with lower BIC, BA, and BD around implant in OVX group compared with other two groups, and Simvastatin reversed the negative effect of OVX on bone healing around implants with the improvement of BIC, BA, and BD in zone B. Conclusion: Osteoporosis can significantly influence bone healing in the cancellous bone around titanium implants and Simvastatin was shown to significantly improve the osseointegration of pure titanium implants in osteoporotic rats.     

Intermittent administration of parathyroid hormone improves bone quality and quantity around implants in rat tibiae

ObjectivesIntermittent injection of parathyroid hormone (PTH) is used to treat osteoporosis. The concept of bone quality was updated 20 years ago; however, these updates have not been adopted in implant dentistry. This study aimed to investigate the effects of intermittent administration of PTH on bone quality around implants in rat tibiae.MethodsGrade IV-titanium-threaded implants that were 3.5 mm long and 2.0 mm wide were placed in a randomly selected side of the proximal tibiae of 12-week-old female Wistar rats. Three weeks after implant placement, the rats were randomly divided into PTH-administration and saline-injection groups (PTH and VC, respectively; n = 7 per group). Micro-computed tomographical, histomorphometric, and immunohistochemical analyses were performed to evaluate bone quality and quantity surrounding the implants.ResultsPTH significantly increased bone volume and bone mineral density in bones not associated with the implants as compared to these values in the VC group. PTH significantly increased bone area and the amount of collagen within the total inside areas of all implant threads compared to that observed in VC. Moreover, PTH significantly increased the number of osteoblasts, osteocytes, and osteoclasts in the total inside and/or outside areas of all implant threads and altered the ratio of type I and III collagen to total collagen fibers.ConclusionsWithin the limitations of this study, intermittent administration of PTH improved both bone quantity and bone quality based on the types and numbers of bone cells and the types of collagen fibers surrounding implants placed into rat tibiae.     

实验性骨质疏松症对种植体周围骨量及骨结合的影响

目的 研究骨质疏松症对种植体周围骨量及骨结合的影响。方法 于３２周龄Ｗｉｓｔａｒ雌性大白鼠胫骨骨骺端植入羟基磷灰石（ＨＡ）种植体,术后５６ｄ实验组行卵巢摘除术,对照组行假手术。该术后２８、８４、１６８ｄ分别处死动物取胫骨、制作研磨切片标本,应用骨形态测量学技术探讨种植体周围单位骨量及与新生骨接触面积率的动态变化。结果 卵巢摘除术后２８ｄ,实验组单位骨量与对照组比较,差异有显著性;骨皮质部骨与种植体     

Effect of estrogen replacement and calcitonin therapies on bone around titanium implants placed in ovariectomized rats: a histometric study

PURPOSE: The aim of the present study was to evaluate whether hormone replacement therapy (HRT) and calcitonin (CT) administration could influence bone healing around implants placed in ovariectomized (OVX) rats. MATERIALS AND METHODS: One screw-type titanium implant was placed bilaterally in OVX rats. The animals were assigned to one of the following groups: group 1 (n = 15), sham surgeries; group 2 (n = 15), OVX rats; group 3 (n = 14), OVX rats administered CT 4 days/week (16 IU/kg); group 4 (n = 14), OVX rats administered 17beta estradiol daily (20 microg/kg). After 60 days, the animals were sacrificed and undecalcified sections obtained. Bone-to-implant contact (BIC) and bone area (BA) around the implants were determined separately for the cortical (zone A) and cancellous (zone B) bone areas. RESULTS: In zone A, intergroup analysis did not reveal a significant difference regarding BIC. In contrast, the HRT group (group 4) presented greater BA than groups 2 and 3 (P < .05). Data from zone B revealed that HRT eliminated the negative effect of the ovariectomy on BIC and BA (P < .05), while CT had no effect (P > .05). DISCUSSION: It was the first study to evaluate and demonstrate the impact of HRT and CT on bone around titanium implants in an estrogen-deficient model. CONCLUSION: Within the limits of the present study, it may be concluded that HRT may prevent the influence that estrogen deficiency exerts on bone healing around titanium implants.     

Bone reactions around hydroxyapatite-coated implants in ovariectomized rats

OBJECTIVE: The purpose of this study was to investigate bone reaction after implantation in an estrogen-deficient state by examining the changes in bone reactions within tissue surrounding implants in ovariectomized rats. STUDY DESIGN: Ninety-six 12-week-old female Wistar rats were used in the study; they were divided into 2 groups, an ovariectomized group and a sham-operated group. Hydroxyapatite-coated implants were placed in the proximal metaphyses of the tibiae 21 days after surgery. The tibiae were examined histologically by undecalcified sections at various intervals from 7 to 168 days after surgery. RESULTS: In the cortical bone area of the ovariectomized rats, the procedure did not induce any apparent changes in bone volume around the implant or in bone contact with the implant in comparison with the sham-operated rats. In contrast, both bone volume around the implant and contact of the implant with new bone were significantly decreased in the cancellous bone area in the ovariectomized rats in comparison with the sham-operated rats. CONCLUSIONS: Ovariectomy did not seriously affect bone healing after the placement of implants in cortical bone areas, but it reduced the bone contact ratio and the bone in the cancellous bone area.     

甲状旁腺素对共培养的髁突软骨细胞和BMSCs成骨分化的影响

目的:研究甲状旁腺素(PTH)在持续性或间歇性作用方式下对共培养的髁突软骨细胞和BMSCs分化和骨质形成的影响.方法:根据PTH应用方式不同分为3组:PTH持续应用组、PTH间歇应用组、空白对照组.用茜素红染色检测培养6 d和14 d后,各组细胞矿化结节的形成情况;用碱性磷酸酶检测试剂盒检测碱性磷酸酶活性,应用Western blot和Real-time PCR检测BMSCs成骨分化、骨形成相关蛋白和基因mRNA.结果:PTH间歇应用组在6 d和14 d时形成的矿化结节数量最多,而PTH持续性应用组形成的矿化结节在3组中数量最少.经过6 d和14 d的PTH作用,PTH间歇应用组的ALP活性,RUNX2、BSP和MMP13蛋白,成骨分化标志物RUNX2,ALP和骨形成相关基因OCN及OSX的表达,均明显高于PTH持续应用组和空白对照组(P<0.05).PTH持续应用组COL2a1的mRNA及成骨抑制基因SOST mRNA的表达量明显高于PTH间歇应用组(P<0.05).结论:间歇性应用PTH可明显促进共培养体系的成骨向分化及骨质形成,而持续性应用PTH则抑制该过程.     

Bone density around titanium implants may be influenced by intermittent cigarette smoke inhalation: a histometric study in rats

PURPOSE: This study investigated the influence of cigarette smoke on bone healing around titanium implants placed in rats. MATERIALS AND METHODS: After administration of anesthesia, the tibia surface was exposed and screw-shaped titanium implants (4.0 mm in length and 2.2 mm in diameter) were placed bilaterally (1 each side). The animals (n = 32) were randomly assigned to either group 1 (control, n = 18) or group 2 (intermittent cigarette smoke inhalation, n = 14). After 60 days, the animals were sacrificed and undecalcified sections obtained. Bone density (the proportion of mineralized bone in a 500-microm-wide zone lateral to the implant) was measured in the cortical (zone A) and cancellous bone (zone B) areas. RESULTS: In zone A, a slight difference in bone density was noted between the groups (96.18% +/- 1.08% and 95.38 +/- 1.17% in groups 1 and 2, respectively; P > .05) but was not statistically significant. In contrast, bone density was significantly decreased in zone B in the animals that were exposed to cigarette smoke (17.57 +/- 6.45% and 11.30 +/- 6.81% for groups 1 and 2, respectively; P < .05). DISCUSSION: Whether different results would be observed if animals were exposed to cigarette smoke for a longer period of time and/or before implant placement remains to be investigated. CONCLUSION: Although intermittent cigarette smoke exposure may not seriously affect cortical bone density, it may jeopardize bone quality around titanium implants in the cancellous bone area.     

Effect of a multiphasic anodic spark deposition coating on the improvement of implant osseointegration in the osteopenic trabecular bone of sheep

PURPOSE: Anodic spark deposition techniques have been effectively applied to achieve a microporous morphology on metals. To investigate the effect of a new anodic spark deposition-based treatment in the enhancement of titanium implant osseointegration in trabecular bone of aged and ovariectomized sheep, a histomorphometric and microhardness study was carried out. MATERIALS AND METHODS: Ten sheep were divided into 2 groups. Five were submitted to a bilateral ovariectomy to induce an estrogen-deficiency osteopenia (Ovariectomized), and 5 were left untreated (Aged). Twenty-four months later, they underwent a bilateral implantation of commercially pure titanium screw threads in the lateral surface of femoral condyles: electrochemically treated titanium (SP) and acid-etching treated titanium (BioRough). Twelve weeks after the second operation, the animals were sacrificed and femur segments and iliac crest biopsy specimens were examined for histomorphometric and microhardness evaluations. RESULTS: The histomorphometry of the trabecular bone of the iliac crest biopsy specimens and that around screws showed marked signs of bone rarefaction in the Ovariectomized group when compared to the Baseline and Aged groups. Significantly greater bone-implant contact was observed for SP implants in comparison with BioRough implants in both the Aged (P < .001) and Ovariectomized (P < .01) groups. No significant differences in terms of microhardness were found between SP and BioRough implants within the Aged group, while a significantly higher Bone Maturation Index was observed for SP in the Ovariectomized group (P < .05). CONCLUSIONS: The novel electrochemical treatment SP produced the most promising results and was able to introduce substantial improvements in achieving the fast and stable osseointegration of implants in osteopenic bone.     

Radiographic assessment of bone density around integrated titanium implants after ovariectomy in rats

OBJECTIVES: This study evaluated the influence of ovariectomy 8 weeks after implant placement on bone integrated to titanium implants. MATERIAL AND METHODS: Thirty-eight female rats were submitted to a titanium implant at the tibiae proximal methaphysis. After a healing period of 8 weeks the animals were randomly divided into three groups: control (CTL-10 animals), sham-operated (SHAM-14 animals) and ovariectomy (OVX-14 animals). The CTL group was then sacrificed in order to confirm integration of the implant. The SHAM group was submitted to fictitious surgery and the OVX group was submitted to bilateral ovariectomy. After 12 weeks post-implant placement, the SHAM and OVX groups were sacrificed. In order to confirm the systemic osteopenia in rats, a dual-energy X-ray absorptiometry (DXA) was performed. For the evaluation of bone density, digital radiographs were taken. The grey level of the bone adjacent to implant was measured using image software and the bone density was calculated at six points on both sides of the implant. RESULTS: Densitometry measurements of the femur confirmed systemic bone mass loss in the OVX group. Individualized bone analyses of different regions surrounding the implant showed a significantly lower radiographic bone density (P < 0.05) in the cancellous region of the OVX group (77.48 +/- 23.39 grey levels) when compared with the CTL and SHAM groups (91.61 +/- 32.10 and 102.57 +/- 32.50 grey levels, respectively). CONCLUSIONS: The present study showed a decrease of the radiographic bone density in the cancellous region of bone around titanium implants placed 8 weeks before ovariectomy in rats.     

转化生长因子-β1基因治疗对种植体周骨质疏松的影响

目的探讨转化生长因子- β1（TGF- β1）基因治疗对种植体周围骨质疏松和骨缺损的影响。方法构建pCDNA3.1（+）- TGF- β1真核表达载体，转染大鼠骨髓间充质干细胞（BMSCs），并与聚乳酸- 羟基乙酸（PLGA）体外黏附。制备骨质疏松大鼠股骨植入钛种植体模型，将24只Wister大鼠随机分为实验组、对照组和空白对照组，实验组为在种植体周骨缺损处植入TGF- β1基因修饰BMSCs复合PLGA；对照组为BMSCs复合PLGA。术后第4和8周取标本行免疫组化和组织学分析，观察种植体周骨组织中TGF- β1的表达和组织学变化。结果术后第4周，实验组骨缺损区的TGF- β1表达较对照组和空白对照组明显；第8周实验组骨缺损区被新生骨充填，骨质较对照组和空白对照组明显改善。结论TGF- β1基因修饰BMSCs体内回植后，可在种植体周围骨组织内表达TGF- β1，并可以影响种植体周骨缺损的修复和骨质疏松状况。     

Effect of estrogen and calcitonin therapies on bone density in a lateral area adjacent to implants placed in the tibiae of ovariectomized rats

BACKGROUND: This study evaluated the influence of estrogen and calcitonin administration on tibial bone density in a lateral area adjacent to implants placed in ovariectomized rats (OVX). METHODS: One screw-type titanium implant was placed bilaterally in the ovariectomized rats, and the animals assigned to one of the following groups: group 1 (n = 15): sham surgeries; group 2 (n = 15): OVX; group 3 (n = 14): OVX subcutaneously administered with calcitonin (CT) 4 days/week (16 IU/kg); group 4 (n = 14): OVX administered daily with 17beta estradiol (20 microg/kg). After 60 days, the animals were sacrificed and undecalcified sections obtained. Blood samples were collected to measure serum levels of alkaline phosphatase and calcium at the time of sacrifice. Bone density was measured in a 500 microm wide mineralized zone lateral to the implant. RESULTS: Alkaline phosphatase levels in groups 2 and 3 (P > 0.05) were statistically higher than groups 1 and 4 (P < 0.05), and calcium serum levels were higher in group 2 than the other groups (P < 0.05). Regarding bone density, the data were grouped separately for cortical (zone A) and cancellous (zone B) bone. In zone A, intergroup analysis revealed no significant difference among groups (P > 0.05). However, in zone B, the animals that received estrogen administration (group 4) presented a higher bone density than groups 2 and 3 (P < 0.05). CONCLUSION: It appears that estrogen therapy may prevent the negative influence of endogenous estrogen deficiency on bone density around titanium implants placed in ovariectomized rats.     

Estrogen deficiency affects bone healing around titanium implants: a histometric study in rats

The purpose of this study was to evaluate the influence of an estrogen-deficient state on bone around titanium implants placed in rats. Thirty female Wistar rats were divided into 2 groups: test (n = 15), ovariectomized rats (OVX); and control (n = 15), sham-operated rats. Screw-type titanium implants were placed bilaterally in rats 21 days after ovariectomy or sham surgery. After 60 days, the animals were killed and undecalcified sections obtained. Blood samples were collected to obtain serum levels of alkaline phosphatase at the time of killing. Bone-to-implant contact (BIC), bone area (BA) around the implants, and bone density (BD) in a 500 microns-wide zone lateral to the implant were obtained and arranged separately for the cortical (zone A) and cancellous (zone B) regions. In zone A, there was no significant difference between test and control groups regarding BIC and BD (P > 0.05). A lower BA was observed in the estrogen-deficient animals (P < 0.05). In zone B, data analysis showed that estrogen deficiency could result in a lower percentage of BIC, BA, and BD (P < 0.05). In addition, a higher concentration of alkaline phosphatase was observed for the test group. An estrogen-deficient state could affect bone healing and bone density around titanium implants placed in rats, especially in the cancellous bone area.     

Synthetic Parathyroid Hormone May Augment Bone Volume in Autogenous Grafts: A Study in Rats

Background: Synthetic parathyroid hormone [PTH(1–34)] has been investigated for its benefits on bone healing and osteoporosis treatment; however, there is little information regarding bone grafts. This study therefore investigates the effect of PTH(1–34) on autogenous bone graft healing. Methods: Bone grafts were harvested from the calvarium of rats with a trephine bur (3‐mm internal diameter) and placed on the cortex near the mandible angle with a titanium screw. Animals were randomly assigned to group 1 (control): subcutaneous injections of saline solution, three times a week (n = 15); group 2: 2 μg/kg PTH(1–34), three times a week (n = 15); and group 3: 40 μg/kg PTH(1–34), three times a week (n = 15). Thirty days postoperatively, the animals were killed, and specimens (implant + bed + graft) were removed and used for undecalcified sections. The following histometric parameters were evaluated: total bone thickness (TT) (bed + gap + graft), graft thickness (GT) (adjacent to the implant), bone‐to‐implant contact (BIC), and bone area (BA) (within the limits of the threads). Five additional animals were sacrificed immediately after surgery (zero hour) to register bed and graft sizes before healing. Results: Group 3 showed significantly greater bone gain compared with groups 1 and 2 (TT and GT, P <0.05). In relation to initial thickness (zero hour), groups 1 and 2 showed a total decrease in volume of 15.91% and 20.83%, respectively, whereas group 3 showed a slight bone gain (1.21%). Data analysis revealed a significant difference for group 3 compared with groups 1 and 2 (P <0.01). No differences were observed for BIC and BA (P >0.05). Conclusion: Systemic administration of PTH(1–34) augmented bone volume in autogenous grafts.