Histomorphometric analysis and immunolocalization of RANKL and OPG during the alveolar healing process in female ovariectomized rats treated with oestrogen or raloxifene

Objective

To investigate the effects of bone-resorption inhibitors (oestrogen and raloxifene) on the RANKL/OPG balance during the chronology of the alveolar healing process in ovariectomized (OVX) rats by means of immunocolocalization and histomorphometric analysis.

Materials and methods

One hundred sixty female Wistar rats at 70 days of age were either OVX or sham-operated and divided into four groups: sham, OVX/Oil, OVX with E₂ replacement (17β-estradiol, 400 μg/month), OVX with RLX treatment (1 mg/kg bw/day). The 60-day treatment started 8 days after ovariectomy. The incisors were extracted to allow analysis of 7, 14, 21, 28 and 42 days of wound healing. After obtaining the histological samples, slides were stained with hematoxylin and eosin or subjected to immunocolocalization reaction for RANKL and OPG. Results were quantitatively evaluated.

Results

Histomorphometric analysis showed that the sham group presented the highest and OVX/Oil group the lowest mean bone formation value in the post-extraction period. The immunocolocalization analysis showed a larger increase in bone turnover at 7 postoperative days in OVX/Oil and sham groups and decreasing bone turnover in the other periods. The OVX/Oil group showed a large decrease in bone turnover at 14 postoperative days, a period demonstrated by mild cellular activity. OVX/E₂ and sham groups showed a decreased bone turnover at 28 postoperative days while OVX/RLX group showed a decreased bone turnover at 21 postoperative days. On the 42nd postoperative day, sham and OVX/RLX groups showed an established alveolar bone healing process.

Conclusions

Ovariectomy delays the alveolar healing process and interferes with bone turnover through the balance between RANKL and OPG. Oestrogen replacement or raloxifene treatment did not totally recover the oestrogen-deficient state. However raloxifene treatment showed more satisfactory results than oestrogen replacement.     

Dysregulated healing response participates in the pathophysiology of temporomandibular joint ankylosis

This study aimed to characterize samples from patients diagnosed with TMJ ankylosis, using both clinical and histological data.Both clinical and histological analyses of retrieved tissue samples from patients with primary TMJ ankyloses were performed retrospectively (1980–2012). All patients had been subjected to primary arthroplasty. Our study analyzed connective tissue differentiation, ossification patterns, and bone resorption, using histology and immunohistochemistry.Fifteen case records, with a sex ratio of 4:1 (men:woman) and a median age of 8 years, were collected. Six patient samples reported a previous inflammatory event. Histologically, 15 samples exhibited fibrous tissue. Among these, 13 displayed bone at different stages of maturity (fibrous/bony ankylosis). Eleven samples showed aberrant cartilage, characterized by hypertrophic chondrocyte-like cells at the bone/cartilage interface. Four samples revealed inflammatory infiltrate; in one case, this was organized as a lymphoid follicle. Eleven samples showed bone resorption by attached osteoclasts. Interestingly, non-attached osteoclasts were detected, suggesting locally impaired bone remodeling. An association between the presence of mature/lamellar bone and the presence of osteoclasts was observed (p = 0.03). No association was found between previous history of either trauma or infection and the histological type of ankylosis (p = 0.74). There was no association between the histological presence of inflammation or infection and the type of ankylosis (p = 0.63 and p = 0.87, respectively).Retrieved TMJ ankylosis tissues displayed both aberrant ossification and reduced focal bone resorption, suggesting a dysregulated healing response.     

Bone healing in osteoporotic female rats following intra-alveolar grafting of bioactive glass

We have investigated the effect of ovariectomy combined with a low Ca diet on bone healing following the implantation of bioactive glass into extraction sockets, in rats. Ovariectomized rats received a low Ca diet from the day of surgery until sacrifice while sham-operated animals were fed a standard laboratory chow. Two weeks after surgery the upper incisors were extracted and the alveolar sockets in both groups were partially filled with a particulate bioglass (PerioGlas^®). The animals were killed 1, 2, 3 and 9 weeks after tooth extraction and the relative volume fraction of the healing components (bone trabeculae, connective tissue and coagulum remnants) was estimated in histological paraffin sections by a histometric differential point-counting method. The bioglass particles persisted inside the socket for all the experimental periods and, as bone repair proceeded, they were progressively enclosed in newly formed bone trabeculae which in some cases established a close contact with their surface. The volume fraction of neoformed bone trabeculae relative to the volume fraction of connective tissue and coagulum remnants was greater in the sockets of ovariectomized animals implanted with bioglass than in those of the overiectomized non-implanted groups.     

大鼠正畸压力侧牙槽骨改建中RANKL和OPG mRNA的表达

目的研究破骨细胞核因子kB受体活化因子配基（receptor activator nuclear factor kappa B ligand,RANKL）及其伪受体骨保护因子（osteoprotegerin,OPG）的mRNA在大鼠正畸牙移动压力侧牙槽骨改建中的表达变化及时问分布特点。方法选用80只6周龄SD雄性大鼠建立正畸牙移动模型,分别在加力后2d、5d、7d、10d和14d各处死16只大鼠。HE染色观察大鼠牙周组织的形态学变化;TRAP染色计数压力侧牙槽骨组织中的破骨细胞数量;实时定量PCR方法检测RANKL和OPGmRNA的表达变化及时问分布特点。结果骨改建的最活跃期为正畸加力后的第7d,压力侧牙槽骨组织中的TRAP染色阳性破骨细胞计数随加力时间的增加而增加,第7d达到高峰,而后逐渐降低。压力侧牙槽骨组织中的RANKL和OPGmRNA表达水平均随加力时间的增加而增加,第7d达到高峰,而后均逐渐降低。结论RANKL和OPG mRNA表达的变化规律不仅与骨改建过程一致,而且也与TRAP染色阳性破骨细胞数量的变化规律一致。RANKL和OPG与正畸牙移动骨改建过程中破骨细胞的分化、形成和功能密切相关。     

不同去势时间大鼠牙槽骨微结构变化的Micro-CT研究

目的： 观察不同去势时间大鼠牙槽骨微结构的改变,探讨去势时间对牙槽骨骨质疏松程度的影响。方法： 健康未孕雌性SD大鼠24只,随机分为去势组(OVX)与假手术组（sham）,每组各12只,分别在全麻下行双侧卵巢去势术与假手术。于术后3个月及6个月2个不同时间点分别处死每组大鼠各6只,取右侧上颌骨标本行Micro-CT扫描;观察去势3个月及6个月后大鼠上颌第一磨牙根分叉区牙槽骨微结构的改变。采用SPSS16.0软件包对数据进行统计学分析。结果： Micro-CT水平面、矢状面二维图像及三维重建均显示,去势3个月及6个月大鼠牙槽骨骨髓腔面积增加、骨小梁变细、部分发生断裂。骨结构参数分析显示,去势3个月及6个月后,大鼠牙槽骨骨密度（BMD）及骨体积分数（BV/TV）、骨小梁宽度（Tb.Th）均显著低于相应时间假手术大鼠（P<0.05）;去势6个月组较3个月组大鼠牙槽骨骨密度(BMD)、骨体积分数(BV/TV)、骨小梁宽度(Tb.Th)显著降低（P<0.05）。去势3个月及6个月大鼠骨小梁数目（Tb.N）及骨小梁分离度（Tb.Sp）显著高于相应假手术组（P<0.05）,且去势6个月组骨小梁数目(Tb.N)显著高于去势3个月组（P<0.05）。结论： 随着去势时间延长,大鼠牙槽骨骨量降低、骨小梁微结构破坏加剧,骨质疏松程度加重。     

大鼠正畸牙移动压力侧牙槽骨中cathK、RANKL和OPG的表达

目的检测大鼠正畸牙移动压力侧cathK、RANKL和OPG蛋白表达变化及时间分布特点。方法选用80只6周龄SD雄性大鼠建立正畸牙移动模型,分别在加力后2d、5d、7d、10d和14d各处死16只大鼠。HE染色观察大鼠牙周组织的形态学变化;TRAP染色计数压力侧牙槽骨组织中的破骨细胞数量;免疫组化方法定位及相对定量检测压力侧牙槽骨中cathK、RANKL和OPG蛋白表达变化及时间分布特点。结果压力侧牙槽骨组织中的TRAP染色阳性破骨细胞计数随加力时间的增加而增加,第7d达到高峰,此后逐渐降低;压力侧牙槽骨组织中的cathK、RANKL和OPG蛋白的表达水平均随加力时间的增加而增加,第7d达到高峰,以后均逐渐降低。结论cathK、RANKL和OPG蛋白表达的变化规律与骨改建过程一致,与正畸牙移动骨改建过程中破骨细胞的分化、形成和功能密切相关。     

骨折愈合中牙本质基质蛋白1与破骨细胞表达时间效应的观察

目的探讨骨折愈合过程中牙本质基质蛋白1（dentin matrix protein 1，DMP1）与破骨细胞的时间效应。为研究DMP1在体内矿化重建中的作用提供参考。方法将40只成年Wistar雄性大鼠左侧下颌支骨折，建立下颌骨骨折模型。骨折后5、7、14、21d处死大鼠，取骨痂和对侧正常骨组织（对照组），分别采用HE染色、TRAP染色和免疫组织化学链霉抗生物素．蛋白过氧化物酶（streptavidin perosidase，sp）法染色切片检测。结果在对照组正常下颌支组织中没有DMP1的表达，偶见破骨细胞；实验组在骨折后14～21d是破骨细胞活动高峰。结论DMP1与破骨细胞在骨折愈合过程中具有一定的时间效应。     

Influence of low-level laser therapy on the healing process of autogenous bone block grafts in the jaws of systemically nicotine-modified rats: A histomorphometric study

ObjectiveTo analyze the influence of low-level laser therapy (LLLT) on the bone healing process of autogenous bone block grafts installed in nicotine systemically modified rats.MethodsSeventy-two rats (Wistar) were randomly assigned into 4 groups (n = 18). SS-BG: saline application + bone graft. SS-BG/LLLT: saline application + bone graft + LLLT. NIC-BG: nicotine application + bone graft. NIC-BG/LLLT: nicotine application + bone graft + LLLT. After 30 days of application of solutions, all animals received autogenous bone block graft in the jaw, with the donation from the parietal bone’s calvarial area. Treatment with LLLT was in bed-graft interface, after accommodation of the graft. The animals in each group were sacrificed at 7, 14, and 28 days after graft surgery.ResultsThe histologic analyses of NIC-BG group depicted a delay of osteogenic activity in the recipient bed-graft interface and the irradiation of tissue with LLLT provided better bone healing. The histometric analysis revealed that SS-BG/LLLT and NIC-BG/LLLT groups showed increased bone formation compared to BG-SS and NIC-BG groups, after 14 days (SS-BG 24.94% ± 13.06% versus SS-BG/LLLT 27.53% ± 19.07% and NIC-BG 14.27% ± 2.22% versus NIC-BG/LLLT 24.37% ± 11.93%) and 28 days (SS-BG 50.31% ± 2.69% versus SS-BG/LLLT 58 19% ± 12.32% and NIC-BG 36.89% ± 8.40% versus NIC-BG/LLLT 45.81% ± 6.03%).ConclusionNicotine harms bone formation in the bed-graft interface and LLLT action can mitigate this.     

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     

壳寡糖对牙周炎大鼠牙槽骨吸收及Th17/Treg平衡和OPG/RANKL/RANK通路的影响

目的: 探讨壳寡糖对牙周炎大鼠牙槽骨吸收及Th17/Treg平衡和OPG/RANKL/RANK通路的影响。方法: 建立牙周炎大鼠模型,随机分为模型组、壳寡糖低剂量组、壳寡糖中剂量组、壳寡糖高剂量组和甲硝唑组,每组12只,另取12只作为对照组。分组处理后,评估牙龈指数、牙槽骨吸收值;H-E染色观察牙周组织病理形态学变化;流式细胞术检测外周血中Th17/Treg细胞比值;酶联免疫吸附试验（ELISA）检测各组大鼠血清中IL-17、TGF-β、RANKL、OPG水平,实时荧光定量PCR（qRT-PCR）检测各组大鼠牙周组织OPG、RANKL mRNA表达水平。采用SPSS 24.0软件包对数据进行统计学分析。结果: 与对照组相比,模型组大鼠牙周组织呈现牙周膜纤维束断裂、排列紊乱,毛细血管扩张、增生,炎症细胞浸润等病理损伤;牙龈指数、牙槽骨吸收值、Th17/Treg比值、血清RANKL及IL-17水平、牙周组织RANKL mRNA水平显著升高（P<0.05）,血清OPG及TGF-β水平、牙周组织OPG mRNA水平显著降低（P<0.05）。与模型组相比,壳寡糖低、中、高剂量组和甲硝唑组大鼠牙周组织病理损伤减轻;牙龈指数、牙槽骨吸收值、Th17/Treg比值、血清RANKL及IL-17水平、牙周组织RANKL mRNA水平显著降低（P<0.05）,血清OPG及TGF-β水平、牙周组织OPG mRNA水平显著升高（P<0.05）,且壳寡糖各组呈剂量依赖性,壳寡糖高剂量组与甲硝唑组相比,差异无统计学意义（P>0.05）。结论: 壳寡糖可促使Th17/Treg平衡恢复正常,上调OPG表达,下调RANKL表达,抑制牙周炎大鼠牙槽骨吸收,改善其临床症状。     

不同去势时间对大鼠牙槽骨微结构影响的比较研究

目的 比较不同去势时间对大鼠牙槽骨微结构的影响,探讨牙槽骨骨质疏松大鼠模型建立成功的参数。方法 24只6月龄雌性SD大鼠,随机分为4组：（1）对照组1（Sham1）;（2）去势组1（OVX1）;（3）对照组2（Sham2）;（4）去势组2（OVX2）。分别在全麻下行假手术和双侧卵巢去势术。于术后3个月和4个月处死各组大鼠,取双侧上颌骨标本,通过Micro-CT扫描、HE染色、抗酒石酸酸性磷酸酶（TRAP）染色、Van Gieson染色、荧光双标观察并分析牙槽骨微结构的变化。结果 去势3个月后OVX1组与Sham1组大鼠相比,体重增加25.09%（P<0.01）;牙槽骨骨体积分数（BV/TV）、骨小梁数目（Tb.N）、骨小梁分离度（Tb.Sp）,牙骨质界-牙槽嵴顶（CEJ-ABC）距离无改变（P>0.05）,骨小梁宽度（Tb.Th）降低了12.44%（P<0.05）,破骨细胞数量增加了40.12%（P<0.01）;骨形成沉积率（MAR）无明显改变（P>0.05）;去势4个月后OVX1组与Sham1组大鼠相比,体重进一步增加了26.25%（P<0.01）,BV/TV、Tb.Th、MAR分别降低了11.15%、17.22%和38.45%（P<0.01）,Tb.Sp和破骨细胞数量分别增加了81.89%和35.67%（P<0.01）,Tb.N和CEJ-ABC距离无变化（P>0.05）,HE和Van Gieson染色均表明OVX2组大鼠牙槽骨骨量降低,骨髓腔面积增加,骨小梁微结构破坏、变细,部分区域发生断裂。结论 6月龄雌性SD大鼠去势4个月后,牙槽骨发生明显骨质疏松,可作为合适的牙槽骨骨质疏松大鼠模型参数的理论依据。     

Receptor activator of nuclear factor-kappa ligand,OPG, and IGF-I expression during orthodontically induced inflammatory root resorption in the recombinant human growth hormone–treated rats

Objective:To investigate the effects of growth hormone (GH) on local receptor activator of nuclear factor-kappa ligand (RANKL), OPG, and IGF-I expression during orthodontically induced inflammatory root resorption in rats.Materials and Methods:Forty Wistar rats (gender: male; age: 7 weeks) were randomly divided into control and experimental groups. A force of 50 g was applied to move the right upper first molars mesially. The experimental and control groups received daily subcutaneous injections of recombinant human growth hormone (GH; 2 mg/kg) and equivalent volumes of saline, respectively. The rats were sacrificed on days 1, 3, 7, and 14. Micro–computed tomography–reconstructed images of the upper right first molars were used to survey root resorption and tooth movement. Horizontal sections of the maxillae were prepared for hematoxylin and eosin, tartrate-resistant acid phosphatase, and immunohistochemical staining.Results:Resorption lacunae appeared on the compressed side of the distal buccal root of the right first molar on days 7 and 14. Compared with the control groups, GH-treated groups showed more RANKL-positive cells and osteoclasts on day 3 and more OPG- and IGF-I–positive cells and fewer odontoclasts on days 7 and 14. Indexes of root resorption were lower and tooth movement was faster in the GH-treated groups than in the control groups on days 7 and 14.Conclusions:The inhibitory effect of GH on root resorption by heavy force might be mediated by RANKL/OPG and IGF-I. Short-term GH administration may be a method with which to reduce root resorption and shorten treatment time, especially in patients who are susceptible to root resorption.     

Influence of chronic alcoholism and estrogen deficiency on the immunohistochemical expression of regulatory proteins of the bone resorption process in the periodontium of Wistar rats

ObjectiveThe aim of this study was to investigate possible changes in immunohistochemical expression of proteins regulating the bone resorption process in the periodontium of rats subjected to alcoholism and/or estrogen deficiency. The investigated proteins were receptor activator of nuclear factor-kappa β ligand (RANKL), a protein that stimulates bone resorption, and osteoprotegerin (OPG), a protein that inhibits bone resorption. At the molecular level, decreased OPG expression and/or increased RANKL expression are consistent with a greater predisposition to bone resorption.DesignWistar female rats were divided into ovariectomized (ovx) and non-ovariectomized (sham) groups, and subdivided into ad libitum diet (free diet), alcoholic diet (20% solution), and isocaloric diet (diet with a similar amount of calories as compared with groups ingesting an alcoholic diet). The alveolar bone crest and adjacent tissues were evaluated by immunohistochemical analyses for detection of OPG and RANKL.ResultsA significant decrease in OPG expression and a significant increase in RANKL expression were observed in ovariectomized animals which received alcohol as compared with non-ovariectomized animals which received isocaloric diet (experimental control). When estrogen deficiency was evaluated independently of the diet type, a significant decrease in OPG expression and a significant increase in RANKL expression were observed in ovariectomized animals as compared with non-ovariectomized animals.ConclusionsEstrogen deficiency associated with alcoholic diet, as well as estrogen deficiency (analyzed independently of diet type), decreased the immunostaining for OPG and increased the immunostaining for RANKL in the periodontium of rats.     

Oxytocin promotes bone formation during the alveolar healing process in old acyclic female rats

ObjectiveOT was reported to be a direct regulator of bone mass in young rodents, and this anabolic effect on bone is a peripheral action of OT. The goal of this study was to investigate the peripheral action of oxytocin (OT) in the alveolar healing process in old female rats.Materials and methodsFemales Wistar rats (24-month-old) in permanent diestrus phase, received two ip (12 h apart) injections of saline (NaCl 0.15 M – control group) or OT (45 μg/rat – treated group). Seven days later, the right maxillary incisor was extracted and analyses were performed up to 28 days of the alveolar healing process (35 days after saline or OT administration).ResultsCalcium and phosphorus plasma concentrations did not differ between the groups. The plasma biochemical bone formations markers, alkaline phosphatase (ALP) and osteocalcin were significantly higher in the treated group. Histomorphometric analyses confirmed bone formation as the treated group presented the highest mean value of post-extraction bone formation. Tartrate-resistant acid phosphatase (TRAP) was significantly reduced in the treated group indicating an anti-resorptive effect of OT. Immunohistochemistry reactions performed in order to identify the presence of osteocalcin and TRAP in the bone cells of the dental socket confirmed these outcomes.ConclusionsOT was found to promote bone formation and to inhibit bone resorption in old acyclic female rats during the alveolar healing process.     

The association between the masseter muscle, the mandibular alveolar bone mass and thickness in dentate women

Objective: Since muscle strength has been demonstrated to affect the bone in the long bones and spine, the possibility exists that the bone mass and dimension of the alveolar processes could be influenced by the function of the masticatory muscles. Therefore, the purpose of this study was to investigate whether two local factors (ultrasonographic masseter thickness, and occluding teeth) plus the skeletal bone mineral density (BMD) affect the mandibular alveolar bone mass (MABM) and the bucco-lingual alveolar thickness of the alveolar process.

Design: The thickness of the masseter muscle was evaluated by ultrasound imaging in 62 dentate women (40–75 years) with no periodontal disease and no dental infection in the premolar region consecutively selected from the patients in a public dental clinic. MABM was evaluated using periapical radiographs. The bucco-lingual thickness of the alveolar process was measured on dental casts with a dial calliper. BMD of the forearm was determined with dual energy X-ray absorptiometry.

Results: Multiple regression analyses demonstrated that masseter thickness and the number of occluding mandibular teeth in the lateral segment were significant determinants of MABM and of the interdental thickness, but BMD was not. The number of years after menopause and struma/gastro-intestinal disease influenced MABM but not the alveolar thickness.

Conclusion: The local factors played an important role in the posterior mandibular segment and their effect might partly explain the low correlation between MABM and skeletal BMD.     

Histological and immunohistochemical analyses of the chronology of healing process after immediate tooth replantation in incisor rat teeth

Abstract – Dental tissues have special characteristics, and its regenerative capacity is noteworthy. However, understanding the circumstances that lead to regeneration is challenging. In this study, the chronology of the healing process after immediate replantation of rat incisor teeth was examined by histological and immunohistochemical analyses within a 60‐day period. Thirty‐six male Wistar rats had their maxillary right incisors extracted and replanted after 15 min in saline storage. The rats were sacrificed immediately 3, 7, 15, 28, and 60 days after replantation. The histological analysis showed rupture of the periodontal ligament and formation of a blood clot, which started being replaced by a connective tissue after 3 days. At 7 days, the gingival mucosa epithelium was reinserted and areas of root resorption could be seen. At 15 days, the periodontal ligament was repaired. At 3 days, the pulp presented an absence of the odontoblast layer, which started being replaced by a connective tissue. This tissue suffered gradual calcification, filling the root canal at 28 and 60 days. The root ends were closed. The immunohistochemical analysis revealed greater expression of OP, OPG, and RANK proteins in the initial periods (0 and 3 days), while TRAP expression predominated at 28 and 60 days (P < 0.05). In conclusion, in delayed tooth replantation, there is great new bone formation activity in the earlier periods of the repair process, while a predominance of bone resorption and remodeling is observed in the more advanced periods.     

正畸牙移动压力侧牙槽骨中cathepsin K、RANKL和OPG mRNA及蛋白的表达

目的检测大鼠正畸牙移动压力侧cathepsinK、RANKL和OPGmRNA及蛋白表达变化及时间分布特点。方法选用80只6周龄SD雄性大鼠建立正畸牙移动模型,分别在加力后2d、5d、7d、10d和14d各处死16只大鼠。HE染色观察牙周组织的形态学变化。TRAP染色计数压力侧牙槽骨中的破骨细胞数量。免疫组化方法定位及相对定量检测cathepsinK、RANKL和OPG蛋白表达变化及时间分布特点。Real—timePCR检测cathepsinK、RANKL和OPGmRNA表达变化及时间分布特点。结果骨改建的最活跃期为正畸加力后的第7d。压力侧牙槽骨中的TRAP染色阳性破骨细胞计数随加力时间的增加而增加,第7d达到高峰,而后逐渐降低。压力侧牙槽骨中的cathepsinK、RANKL和OPGmRNA及蛋白的表达水平均随加力时间的增加而增加,第7d达到高峰,而后均逐渐降低。结论cathepsinK、RANKL和OPGmRNA及蛋白表达的变化规律不仅与骨改建过程一致,而且也与TRAP染色阳性破骨细胞数量的变化规律一致。cathepsinK、RANKL和OPG与正畸牙移动骨改建过程中破骨细胞的分化、形成和功能密切相关。     

细胞凋亡及其相关基因Bcl-2和 Bax在大鼠正畸牙槽骨改建中的作用

目的：观察大鼠正畸牙齿移动中牙槽骨的细胞凋亡现象以及凋亡相关基因Ｂｃｌ－２和Ｂａｘ的表达,初步探讨细胞凋亡在牙槽骨改建中的作用。方法：选用２５只健康雄性ＳＤ大鼠,用单簧圈别针簧矫治器推上颌切牙侧向移动,于加力后１、３、５、７ｄ系列观察牙槽骨中细胞凋亡及其相关基因Ｂｃｌ－２和Ｂａｘ的表达,以正常组为对照,用免疫组织化学方法和ＴＵＮＥＬ法进行检测。结果：正常牙槽骨组织中存在凋亡细胞,主要见于骨细胞,呈散在性分布,数量较少。牙齿移动时,压力侧牙槽骨改建活跃,凋亡细胞有增多趋势,而张力侧牙槽骨凋亡细胞呈减少趋势。在成骨细胞、破骨细胞、透明性变区未检测到凋亡细胞。Ｂｃｌ－２和Ｂａｘ在正常牙槽骨细胞均有表达,在压力侧Ｂａｘ的表达强于Ｂｃｌ－２,在成骨细胞和破骨细胞Ｂｃｌ－２的表达强于Ｂａｘ。结论：细胞凋亡及其相关基因Ｂｃｌ－２和Ｂａｘ参与了正畸牙齿移动过程中牙槽骨的改建过程。     

Quantitative assessment of post-extraction healing and alveolar ridge remodelling of the mandible in female rats

OBJECTIVE: To quantitatively evaluate the healing and bone changes in the mandible of adult female rats following unilateral extraction of the mandibular molars and the incisor. METHODS: Six-month old female rats had their mandibular molars and the incisor on one side of the mandible extracted. Nine rats were sacrificed at 0, 14, 28, 56 and 112 days post-extraction. Bone mineral density (BMD) as observed by dual energy X-ray absorptiometry (DEXA) and histomorphometric measurements of total bone volume (TBV/TV%) as well as changes in size; height and width on backscattered electron microscopy images of cross-sections of the mandible were evaluated. RESULTS: There was a total increase of 28% in BMD of the body of the mandible and 35.1% increase in TBV/TV% at 112 days post-extraction. A maximal increase of 25% in BMD was observed at 14 days post-extraction. TBV/TV% increased by 9.5% at 14 days post-extraction and further increased by 15.9% (P < 0.001) from 14 to 28 days and by 9.2% (P < 0.001) from 28 to 56 days. A further slight but non-significant increase of 6% (P = 0.108) occurred from 56 to 112 days post-extraction. Regression equations demonstrated that the maximal increase in TBV/TV% and BMD occurred between 0 and 28 days, which subsequently slowed down between 28 and 56 days and further declined between 56 and 112 days post-extraction. Healing was associated with a reduction in cross-sectional area (32.89%), height (21%) and width of the mandible (12.84%). CONCLUSIONS: BMD of the edentulous mandible following extraction of mandibular molars and the incisor on one side of the mandible increases up to 56 days, but that total bone volume increases up to 112 days post-extraction. This indicates that bone volume measurement is more sensitive than BMD measurements in detecting small increase in bone formation at later stages of healing, possibly because of changes in geometry of the edentulous mandible following teeth extraction. The edentulous mandible undergoes a significant reduction in size as a result of reduction in both height and width up to 112 days post-extraction.