Histochemical examination of blood vessels in murine femora with intermittent PTH administration

ObjectiveTo verify the biological effects of parathyroid hormone (PTH) on the blood vessels in the bone, this study aimed to investigate histological alterations in endomucin-positive blood vessels and perivascular cells in murine femora after intermittent PTH administration. For comparison with blood vessels in the bone, we examined the distribution of endomucin-positive blood vessels and surrounding αSMA-immunoreactive perivascular cells in the liver, kidney, and aorta with or without PTH administration.MethodsSix-week-old male C57BL/6J mice received hPTH [1–34] or vehicle for two weeks. All mice were fixed with a paraformaldehyde solution after euthanasia, and the right femora, kidney, liver, and aorta were extracted for immunohistochemical analysis of endomucin, αSMA, ephrinB2, EphB4, and HIF1α. Light microscopic observations of semi-thin sections and transmission electron microscopic (TEM) observations of ultra-thin sections were performed on the left femora.ResultsAfter intermittent PTH administration, αSMA-reactive/ephrinB2-positive stromal cells appeared around endomucin-positive/EphB4-immunoreactive blood vessels in the bone. In addition, intense immunoreactivities of EphB4 and HIF1α were seen in vascular endothelial cells after the PTH treatment. Several stromal cells surrounding PTH-treated blood vessels exhibited well-developed rough endoplasmic reticulum under TEM observations. In contrast to bone tissues, αSMA-positive stromal cells did not increase around the endomucin-positive blood vessels in the kidney, liver, or aorta, even after PTH administration.ConclusionThese findings show that intermittent PTH administration increases αSMA-reactive/ephrinB2-positive perivascular stromal cells in bone tissue but not in the kidney, liver, or aorta, suggesting that PTH preferentially affects blood vessels in the bone.     

Effect of simvastatin administration on periodontitis-associated bone loss in ovariectomized rats

BACKGROUND: Hydroxyl methylglutaryl-coenzyme A reductase inhibitors, so-called statins, have been widely used for hyperlipidemic patients. Recently, it has been reported that they promote bone formation. The purpose of this study was to evaluate the effect of simvastatin on ligature-induced bone resorption in the mandible of the ovariectomized rat. METHODS: Forty-nine rats were divided into seven groups; ligature was placed in all groups except group 7, which was considered the sham group: group 1 (N = 7), ovariectomy (OVX) plus simvastatin (10(-6) M); group 2 (N = 7), OVX plus simvastatin (3 x 10(-7) M); group 3 (N = 7), OVX plus simvastatin (10(-7) M); group 4 (N = 7), OVX plus normal saline; group 5 (N = 7), OVX group; group 6 (N = 7), ligature without OVX; and group 7 (N = 7), sham surgery without OVX and ligature. Simvastatin was administered subperiosteally in the buccal fold of the bottom right first molar twice a week during the study. Four weeks after insertion of the ligatures, the animals were sacrificed. Mandibles were removed for radiologic and histologic analysis. Bone density, bone loss (BL), and attachment loss were measured. Analysis of variance (ANOVA) was used to compare groups. RESULTS: Histologic analysis showed that the simvastatin groups developed significantly less periodontal breakdown (P <0.05). BL was less in the simvastatin experimental group, but there was not a significant statistical difference between the simvastatin groups (groups 1 through 3) and the experimental control groups (groups 5 and 6; P >0.05). CONCLUSION: Within the limits of this study, it can be concluded that simvastatin shows protective features against the impact of periodontitis on attachment apparatus and alveolar bone.     

PTH_(1-34)与种植体骨结合相关性的研究进展

骨结合是影响种植体质量的主要因素。它包括初期种植体与牙槽骨之间的机械嵌合和后期种植体周期骨组织的新生与改建。种植材料的生物相容性,种植体的表面结构与性能,种植体植入手术的创伤,种植床的愈合能力,种植体的负荷状况等都会对种植体骨结合的质量产生影响。PTH_(1-34)作为一种针对骨的蛋白合成剂,短期成骨效果明显,促进骨结合形成,在口腔种植领域具有广阔的应用前景。本文从PTH_(1-34)在骨结合方面的基础实验及临床应用进行综述。     

雷洛昔芬防治骨质疏松大鼠牙周炎牙槽骨吸收的实验研究

目的:探讨雷诺昔芬对骨质疏松大鼠实验性牙周炎牙槽骨吸收的防治作用.方法:选用3~4 月龄雌性SD大鼠,随机分为假手术组(SHAM)、卵巢切除组(OVX)、雷诺昔芬治疗组(RAL)及雌激素治疗组(EST),每组8 只.采用卵巢切除术及钢丝结扎法建立骨质疏松大鼠实验性牙周炎动物模型,灌胃给药7 周后处死,通过体重、骨密度测量、血清生化检测及组织学观察对药效进行评价.结果: RAL 组大鼠骨密度值明显高于OVX 组,血清碱性磷酸酶及骨钙素水平下降,而血清雌二醇水平显著增加.股骨骨小梁排列整齐,皮质骨致密,与EST 组及SHAM 组比较无明显差别.OVX 组牙周炎牙槽骨吸收(0.33±0.02) mm2,明显大于RAL、EST 组及SHAM 组[(0.18±0.02) mm2、(0.19±0.02) mm2、(0.20±0.01) mm2](P<0.01).结论: 雷诺昔芬可在一定程度上抑制骨质疏松大鼠实验性牙周炎所致病理性牙槽骨吸收.     

Intermittent administration of parathyroid hormone ameliorated alveolar bone loss in experimental periodontitis in streptozotocin-induced diabetic rats

ObjectiveIntermittent administration of parathyroid hormone (PTH) has been demonstrated to have anabolic effects on bone metabolism and is approved for use in the treatment of osteoporosis. This study evaluates the role of intermittent PTH administration on alveolar bone loss in streptozotocin (STZ)-induced diabetic rats.DesignFifty male Sprague Dawley rats were randomly divided into the following five groups: (1) a control group (saline placebo without ligature and STZ injection), (2) a PTH group (PTH administration without ligature and STZ injection), (3) an L group (saline placebo with ligature), (4) an L + STZ group (saline placebo with ligature and STZ injection), and (5) an L + STZ + PTH group (PTH administration with ligature and STZ injection). PTH was administered at 75 μg/kg per dose four times a week for 28 days. Subsequently, all rats were sacrificed, and their mandibles were extracted for micro-computed tomography (micro-CT) scanning, as well as histological and immunochemical evaluation.ResultsMicro-CT scanning demonstrated the anabolic effect of PTH on alveolar bone metabolism in STZ-induced diabetic rats (P < 0.05), and histomorphometry indicated that PTH inhibited inflammation of the periodontium and increased the level of osteoblastic activity (P < 0.05). Immunochemical evaluation showed that rats subjected to both ligature placement and STZ injection had the highest receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio and that PTH administration decreased this ratio.ConclusionIntermittent systemic PTH administration effectively reduced alveolar bone loss and ameliorated the manifestation of experimental periodontitis in STZ-induced diabetic rats.     

Effect of obesity on alveolar bone loss in experimental periodontitis in Wistar rats

Obesity has been linked to higher inflammatory status and periodontal breakdown.

Objective

The purpose of this study was to investigate the effect of obesity on alveolar bone loss in experimental periodontitis in rats.

Material and Methods

Twenty-four female Wistar rats were randomly divided into two groups: obese (n=13), which were fed with "cafeteria diet" (CAF diet - high amounts of sucrose and fat) for 90 days in order to gain weight, and non-obese (n=11) regularly fed rats. Ligature-induced experimental periodontitis was created in all animals. Body weight differed statistically between obese and non-obese groups (277.59 and 223.35 g, respectively) at the moment of the ligature placement. Morphometric registration of alveolar bone loss was carried out after 30 days of ligature placement to determine the effect of obesity on the progression of experimental periodontitis.

Results

Intra-group comparisons showed significantly higher alveolar bone loss mean values in maxillary teeth with ligature (P<0.05). Alveolar bone loss [mean (SD), mm] was not statistically different between obese and non-obese groups [0.71 (0.09) and 0.65 (0.07) mm, respectively]. However, when palatal sides are analyzed separately, obese group presented significantly higher alveolar bone loss (P<0.05) as compared to non-obese [0.68 (0.12) and 0.53 (0.13) mm, respectively].

Conclusions

In spite of the weak differences, it is possible to conclude that the progression of alveolar bone loss in ligature-induced periodontitis can be potentially influenced by body weight in rats.     

人甲状旁腺激素1-34对大鼠牙本质形成和矿化的影响

目的:观察人甲状旁腺激素1-34(human parathyroid hormone1-34,hPTH1-34)对牙本质的形成和矿化的影响,探讨PTH影响牙本质形成和矿化的机制。方法:切除大鼠甲状旁腺,建立牙本质发育不全的动物模型后,再人工给予不同剂量的hPTH1-34,检测血钙水平的变化,42d后处死大鼠,取下颌切牙制作切片,HE染色,光镜观察并进行图像分析。结果:切除甲状旁腺的大鼠血钙水平下降,牙本质矿化缺陷。在给予hPTH1-34皮下注射后可以检测到血钙水平上调,光镜观察和图像分析结果发现牙本质的形成和矿化发生逆转,10nmol/kg组和20nmol/kg组作用效果优于5nmol/kg组(P<0.05)。结论:PTH可能通过调节血钙或其自身直接作用影响牙本质的形成和矿化。     

Effect of bone loss simulation and periodontal splinting on bone strain: Periodontal splints and bone strain

Objectives

The influence of bone loss and periodontal splinting on strains in supporting bone is still not well understood. The aim of this study was to analyse the effect of bone loss and periodontal splints on strains in an anterior mandible structure.

Methods

Ten anterior mandible models were fabricated using polystyrene resin. Eighty human teeth were divided in 10 groups (right first premolar to left premolar) and embedded in simulated periodontal ligament. Strain gauges were attached to the buccal and lingual mandible surfaces. The models were sequentially tested for 7 conditions: no bone alterations and no splinting; 5 mm of bone loss between canine teeth; bone loss associated with resin splint between canine teeth; bone loss with wire splint; bone loss with wire/resin splint; bone loss with extracoronal fibre–glass/resin splint; and bone loss with intracoronal fibre–glass/resin splint. Oblique loads (50, 100, and 150 N) were applied on the teeth. Data were analysed using 3-way ANOVA and Scheffe's test (α = .05).

Results

Strains on buccal surface were higher than on lingual surface. Bone loss resulted in strain increase at 100 and 150 N loading. Dental splinting with resin resulted in strain values similar to the control levels.

Conclusions

Bone loss increased strain mainly in the buccal region. Dental splints with adhesive system and composite resin produced lower bone strains irrespective of occlusal load.     

类风湿性关节炎患者牙周骨丧失程度的临床研究

目的:揭示类风湿性关节炎患者关节炎严重程度与牙周骨丧失程度的相关性。方法: 70例类风湿关节炎患者根据牙周附着丧失与牙槽骨吸收程度分为2组:无、轻度骨丧失组和中、重度骨丧失组。分别检查患者晨僵持续时间、红细胞沉降率以及血清C反应蛋白,并进行分析。结果:经统计学分析, 2组在晨僵时间、红细胞沉降率及C反应蛋白水平均有显著性差异,中、重度组均高于无、轻度组。结论:类风湿关节炎患者牙周骨丧失的程度与其类风湿临床症状严重程度密切相关。     

实验性咬合紊乱对大鼠髁突软骨中PTHrP及其受体PTH1R表达的影响

目的：探讨实验性咬合紊乱致大鼠髁突软骨异常改建过程中PTHrP及其受体PTH1R的表达变化情况。方法：在8周龄SD大鼠第二、三磨牙之间填塞正畸用橡皮筋推第三磨牙向远中移动,8周后取双侧颞下颌关节,苏木精-伊红染色观察组织形态变化,免疫组化及RT-PCR方法检测PTHrP及其受体PTH1R表达情况。结果：实验组髁突软骨后部明显增厚（P=0.032）,且出现典型退行性变,软骨中PTHrP（P=0.034）及PTH1R（P=0.031）的mRNA表达明显低于空白对照组。结论：PTHrP及其受体PTH1R参与实验性咬合紊乱所致髁突软骨异常改建。     

阿仑膦酸钠与雌激素对实验性骨质疏松大鼠种植体骨结合作用的比较研究

目的研究抗骨质疏松药物对骨质疏松状态下种植体骨结合的作用。方法40只12周龄雌性SD大鼠，随机分为四组，每组10只：伪手术组（S组）、卵巢切除组（O组）、OVX＋雌激素组（E组）、OVX＋阿仑膦酸钠组（A组）。S组伪手术12周后，O组、E组、A组卵巢切除12周后双侧股骨进行种植手术。种植术后E组腹腔注射苯甲酸雌二醇；A组阿仑膦酸钠灌胃。各组分别在种植术后6周、12周处死。取右侧胫骨QCT行骨密度测量；左侧带种植体股骨行硬组织切片及骨组织形态计量学测量；右侧带种植体股骨摄X线片和进行力学测试。结果①体重、血清雌二醇、碱性磷酸酶检测S组均与其余三组有统计学差异，且胫骨骨密度检测亦表明大鼠骨质疏松成功建立。②组织学观察：种植术后6周和12周，S组皮质骨区新生骨组织主要为编织骨和成熟的层板骨，并与种植体紧密结合；松质骨区骨小梁密集，粗细不均；种植体表面有一层较厚的新生骨板包绕，仅有少数区域与骨髓腔直接接触。E组和A组组织学改变与S组相似，而O组松质骨区骨小梁稀疏，结合骨板较薄，种植体表面与骨髓腔相通较多。③骨组织形态计量学：O组比S组、E组和A组骨结合率、松质骨区骨量明显下降，结果有统计学意义。E组、A组与S组未有统计学差异。④力学测试结果：A组拔出力虽低于S组，但明显高于O组和E组，与E组相比有统计学意义。结论抗骨质疏松药物均能提高种植体骨结合。雌激素和阿仑膦酸钠治疗在组织学改变相似的情况下，阿仑膦酸钠由于抑制了破骨细胞的活性，其力学性能较雌激素替代治疗组有统计学意义上的提高。     

重组人生长激素对老年大鼠有无牙颌骨吸收的影响

目的:探讨重组人生长激素(recombinanthumangrowthhormone,rh-GH)对老年性有牙及无牙颌骨吸收的影响。方法:建立去势大鼠老年骨质疏松模型,拔除大鼠一侧下颌磨牙,次日给予rh-GH1mg·kg-1·d-1皮下注射,连续用药10d;术后8周、12周测量大鼠体重变化,并测定大鼠下颌骨的骨密度、骨矿含量、肌组织量、脂肪组织量;测量指标的组间比较,采用方差分析进行统计学处理。结果:rh-GH治疗组去势大鼠的体重增加,有牙及无牙颌骨密度与治疗前比较,差异有显著性(P<0.05)。结论:重组人生长激素能够增加老年大鼠体重,减缓老年大鼠有牙及无牙颌骨的吸收。     

Prevention of trabecular bone loss in the mandible of ovariectomized rats

The effect of therapeutic agents on trabecular bone loss in the mandible was investigated in ovariectomized rats. Eighty-seven Wistar SPF female rats were ovariectomized (OVX) or given a sham operation (Sham), and maintained on a diet containing 0.1% calcium. Four weeks later, groups of OVX rats were treated with estriol (E3), calcitonin (CT), etidronate, or 2-carboxyethylgermanium sesquioxide (Ge-132). The Basal group was maintained on a diet containing 1.0% calcium, and the OVX and sham groups on a diet containing 0.1% calcium. The trabecular bone mineral density (BMD) and trabecular bone mineral content (BMC) in 11 mandibular slices from 0.5 mm at the mesial margin of the first molar to 0.5 mm at the distal margin of the third molar, were measured using peripheral Quantitative Computed Tomography (pQCT). The BMD in the OVX group was lower than that in the Sham group, and decreased BMC was observed only in the molar region. BMD and BMC were increased in the etidronate-treated group, but only BMC was increased in the CT group. E3 treatment increased BMD and BMC; significant increases were also observed beneath the molar. Ge-132 treatment increased both BMD and BMC, especially the latter.     

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.     

重组人生长激素对去势大鼠正畸牙牙周组织改建的影响

目的:探讨重组人生长激素(recombinanthumangrowthhormone,rh-GH)对去势(ovariectomy,OVX)大鼠正畸牙移动后牙周组织细胞变化的影响。方法:30只7周龄SPF级雌性Wistar大鼠随机分为3组:对照组、去势盐水组(OVX-NS组)和去势生长激素组(OVX-GH组)。将去势摘除双侧卵巢和腹部皮下注射rh-GH作为不同处理因素,观察第15天和第30天时3组大鼠正畸牙移动引起牙槽骨受压侧破骨细胞数的变化,并进行组织学观察。用SPSS12.0软件包对数据进行完全随机设计资料的方差分析。结果:对3组大鼠不同时间正畸牙牙槽骨受压侧破骨细胞计数进行比较,发现同一时间3组数据的差异有统计学意义(P<0.05);OVX-NS组比OVX-GH组显著增多(P<0.05),对照组最少;同组相比,第15天处死的大鼠与第30天处死的大鼠其破骨细胞数无显著差异(P>0.05);牙周组织学观察见,OVX-GH组牙周膜的损伤和创伤性炎症较OVX-NS组明显减轻。结论:去势(成年)大鼠腹部皮下注射rh-GH,能够减少其正畸牙移动引起的受压侧破骨细胞数目,同时可促进牙周组织因正畸力所致的病理性变化的恢复,对成年正畸治疗有良好的协同作用。     

Accuracy of radiographic pixel linear analysis in detecting bone loss in periodontal disease: Study in diabetic rats

IntroductionPeriodontitis, a complex infectious disease that may lead to irreversible loss of periodontium, is considered a predisposing agent for developing insulin resistance due to the release of inflammatory mediators, showing a bilateral relationship with diabetes mellitus. The investigation of periodontal disease requires a clinical approach and complete intraoral radiographs, even with increasing concerns about radiation exposure. Thus, this study assesses pixel linear analysis accuracy using digital radiography via Digora® in detecting alveolar bone destruction in diabetic rats with periodontal disease.Methodology40 rats were divided into groups (n = 10): control (C), rats with periodontal disease (PD), experimental diabetic rats (ED), experimental diabetic rats with periodontal disease (ED-PD). Diabetes was induced by streptozotocin and periodontal disease by periodontal ligature. After 30 days, maxillae bone destruction was obtained by linear analysis of vertical bone loss using digital radiography and then assessed by micro-CT and histology. Data were analyzed by ANOVA and Tukey’s test (p < 0.05).ResultsRadiographic, micro-CT and histological analysis presented accurate and similar results. PD and ED-PD groups showed higher bone destruction than C and ED groups (p < 0.05). Moreover, the ED-PD group had higher bone loss than the PD group (p < 0.05).ConclusionThe pixel linear analysis via digital radiography was an accurate, low-cost alternative in detecting alveolar bone loss in this rat model. Micro-CT and histological analysis may also be used to obtain linear measures to assess and compare periodontal bone destruction in diabetic rats.     

Comparison between panoramic and posterior bitewing radiography in the diagnosis of periodontal bone loss

A study is reported comparing the diagnostic yield of panoramic and posterior bitewing radiographs when used to image periodontal bone disease. It is concluded that there is a high concordance between the findings from the two types of radiographs but that the concordance varies with the degree of bone loss and tooth type. Consequently when panoramic radiography is used in clinical practice, the examination should be supplemented by intraoral radiographs in regions when image quality is poor in the panoramic image and where there are structures of special interest.     

雌激素缺乏对大鼠牙槽骨吸收影响的实验研究

目的观察雌激素缺乏对大鼠牙槽骨吸收的影响。方法34只雌性SD大鼠随机分为4组。第1组假手术(n=8),第2组卵巢切除(n=9),第3组卵巢切除加牙周结扎(n=9),第4组卵巢切除、牙周结扎加雌激素治疗(n=8)。适应性喂养7天后行假手术或双侧卵巢切除术。第4组于术后第二天起皮下注射苯甲酸雌二醇．20μg／kg体重／次,三天一次。第3、4两组于卵巢切除术后28天,结扎丝结扎上颌第一磨牙诱导牙周炎。第63天处死全部大鼠。常规取材。观察牙用组织组织学改变。测量牙用骨丧失值(PBL)。比较牙用骨支持率(PBS)。检测血清碱性磷酸酶(ALP)。结果采用成组f检验,第1、2两组的PBL分别为0．398±O．147mm,0．663±0．132哪。PBS分别为O．588±O．058。0．440±0．197,组间差异均有统计学意义(P<0．05);第2、3两组的PBL、PBS组间差异均有统计学意义(P<0．05)。第3组的PBL为0．875±0．197mm,PBS为0．336±O．087;第3、4两组的PBL、PBS组间差别没有统计学意义(P>0．05),第4组的PBL为O．823±0．119mm,PBS为0．360±0．950。结论雌激素缺乏促进牙槽骨吸收,茵斑刺激加剧骨质疏松大鼠牙槽骨的吸收,雌激素替代治疗不能预防骨质疏松大鼠因茵斑刺激引发的牙槽骨吸收。     

The local administration of parathyroid hormone encourages the healing of bone defects in the rat calvaria: Micro-computed tomography,histological and histomorphometric evaluation

ObjectiveTo evaluate the effect of a single-dose local administration of PTH on bone healing in rat calvarial bone defects by means of micro-computed tomography, histological and histomorphometric analysis.DesignCritical-size cranial osteotomy defects were created in 42 male rats. The animals were randomly divided into 3 groups. In the C Group, the bone defect was only filled with a blood clot. In the S Group, it was filled with a collagen sponge and covered with bovine cortical membrane. In the PTH Group, the defect was filled with a collagen sponge soaked with PTH and covered with bovine cortical membrane. The groups were further split in two for euthanasia 15 and 60 days post-surgery. Data was statistically analyzed with t-tests for independent samples or the nonparametric Mann-Whitney test when applicable. Intragroup comparisons were analyzed with paired t-tests (p < 0.05).ResultsMicro-CT analysis results did not demonstrate statistically significant intergroup differences. At 15 days post-surgery, the histomorphometric analysis showed that the PTH Group exhibited a significantly higher percentage of bone formation compared with the S Group. At 60 days post-surgery, a higher percentage of new bone was observed in the PTH group.ConclusionThe results suggest that the local administration of PTH encouraged the bone healing in critical-size calvarial defects in rats.