Effects of long-term cyclosporin therapy on the periodontium of rats

BACKGROUND: The treatment of cyclosporin A triggers an early bone loss and gingival overgrowth. There is a lack of studies exploring the effects of long-term cyclosporin A therapy on alveolar bone homeostasis and gingival tissue. OBJECTIVE: The purpose of this study was to evaluate the effects of long-term therapy with cyclosporin A on the gingival tissue and on the alveolar bone metabolism in rats. MATERIALS AND METHODS: Rats were treated for 60, 120, 180 and 240 days with a daily subcutaneous injection of 10 mg/kg body weight of cyclosporin A. At the end of experimental periods, animals were killed and the serum calcium (Ca(2+)) and alkaline phosphatase levels were measured in all groups. After histological processing, the oral epithelium and the connective tissue, as well as volume densities of alveolar bone (V(b)) and multinucleated osteoclasts (V(o)), were assessed at the region of the lower first molars. RESULTS: Significant increases in the serum alkaline phosphatase were observed in those groups that received cyclosporin A therapy. After 60 and 120 days of the treatment with cyclosporin A, evident gingival overgrowth associated with a significant increase of epithelium and connective tissue was observed, as well as a decrease of the densities of bone and an increase of densities of osteoclasts. After 180 and 240 days of the treatment, there was a reduction of the gingival overgrowth associated with significant decreases of epithelium and connective tissue, as well as an increase of bone densities and a decrease of osteoclasts. CONCLUSION: Within the limits of this experimental study, it can be concluded that the deleterious periodontal effects of cyclosporin A administration may be time-related side-effects.     

The influence of short-term diabetes mellitus and insulin therapy on alveolar bone loss in rats

BACKGROUND: It is well known that the multiple direct and indirect consequences of hyperglycemia in diabetic individuals have been linked to a number of abnormal host effector mechanisms that could lead to an increased risk of developing periodontal disease. OBJECTIVE: The aim of this study was to investigate the effect of short-term experimental diabetes and insulin therapy on the severity of alveolar bone loss in rats, and the effect of experimental periodontitis on glycemic control. METHODS: Seventy-two male Wistar rats were divided into four groups: group I animals were submitted to dental ligature around lower right first molars (ligated); group II consisted of streptozotocin (STZ)-diabetic, ligated rats; group III represented STZ-diabetic, unligated rats; and group IV consisted of insulin-treated (6 U/day), STZ-diabetic, ligated rats. Blood glucose of all diabetic rats was monitored at regular intervals. Standardized digital radiographs were taken after killing at 7, 15 and 30 days to measure the amount of bone loss about the mesial root surface of the first molar tooth in each rat. Results: No significant (p < 0.05) changes in plasma glucose levels of insulin-treated diabetic rats were found among the different examinations after the beginning of insulin therapy. Rats from group II showed significantly greater increases in mean plasma glucose levels at 15 and 30 days after ligature placement compared with rats from group III (p < 0.05). Furthermore, in spite of the significant alveolar bone loss progression that was observed in groups I, II and IV (p < 0.00001; two-way anova), no significant differences among these groups regarding the severity of bone loss (p = 0.77) and no significant interaction between treatment group and time (p = 0.81) were found. CONCLUSIONS: Within the limits of this study, it can be suggested that the severity of periodontal disease was not affected by short-term diabetes, and that experimental periodontitis increased blood glucose levels in uncontrolled diabetic rats.     

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。     

N‐acetylcysteine decreases alveolar bone loss on experimental periodontitis in streptozotocin‐induced diabetic rats

Toker H, Ozdemir H, Balc? H, Ozer H. N‐acetylcysteine decreases alveolar bone loss on experimental periodontitis in streptozotocin‐induced diabetic rats. J Periodont Res 2012; 47: 793–799. © 2012 John Wiley & Sons A/S Background and Objective: The purpose of this study was to evaluate the morphometric and histopathological changes associated with experimental periodontitis in diabetic rats in response to systemic administration of N‐acetylcysteine (NAC), a sulfhydryl‐containing thiol antioxidant. Material and methods: Sixty Wistar rats were divided into six experimental groups: nonligated (NL) group; ligature‐only (L) group; streptozotocin‐only (STZ) group; STZ and ligature (STZ + L) group; and systemic administration of NAC and ligature (70 and 100 mg/kg body weight per day, respectively) (NAC70 and NAC100 groups). Diabetes mellitus was induced by 60 mg/kg of streptozotocin. Silk ligatures were placed at the gingival margin of the lower first molars of the mandibular quadrant. The study duration was 30 d and the animals were killed at the end of this period. Changes in alveolar bone levels were clinically measured and tissues were histopathologically examined to assess the differences among the study groups. Results: At the end of the 30‐d study period, alveolar bone loss was significantly higher in the STZ + L group compared with the other groups (p < 0.05). Also, alveolar bone loss in all the NAC groups was significantly lower than in the STZ + L and L groups (p < 0.05). The osteoblastic activity in the NAC100 group was significantly higher than in the other groups (p < 0.05). Conclusion: Within the limits of this study, it can be suggested that NAC, when administered systemically, prevents alveolar bone loss in the diabetic rat model.     

Effect of age on alveolar bone turnover adjacent to maxillary molar roots in male rats: A histomorphometric study

OBJECTIVE: The effect of age on alveolar bone turnover adjacent to maxillary molar roots of male rats was assessed histomorphometrically with special focus on bone formation and resorption. DESIGN: A total of 110 male Wistar rats ranging in age from 6 to 100 weeks were used for this study. Histomorphometric parameters were measured in fluorescence-labeled undecalcified ground and paraffin-embedded decalcified sections of the alveolar wall around the disto-lingual roots of the maxillary first molars. Bone formation was measured statically by determining the percentage of the bone surface that was double-labeled surface (dLS/BS), bone formation rate (BFR/BS), and mineral apposition rate (MAR). Bone resorption was quantified statically in terms of the number of osteoclasts (N.Oc/BS) and the percentage of the bone surface covered with osteoclasts (Oc.S/BS). RESULTS: For the total surface of the alveolar wall, the values obtained for all parameters of both bone formation and resorption decreased with advancing age. All these values rapidly decreased during the early part of the life span, from 6 to 30-40 weeks of age, of the rats. A site-specific difference between the distal and mesial sides of the alveolar wall was found for each age group. dLS/BS and BFR/BS were significantly greater (p < 0.0001) on the mesial side than on the distal one. On the other hand, the distal side showed significantly greater (p < 0.0001) value for N.Oc/BS and Oc.S/BS did the mesial one. However, there were no significant age-related changes in dLS/BS and BFR/BS on the distal side or in N.Oc/BS and Oc.S/BS on the mesial side throughout observation period. CONCLUSION: The results of the present study demonstrate that alveolar bone turnover of male rats decreased rapidly with advancing age but that in order to maintain the integrity of the tooth function mechanical stress may still have participated in bone formation and resorption of the alveolar wall even in rats 100-week old.     

Alendronate therapy in cyclosporine-induced alveolar bone loss in rats

BACKGROUND AND OBJECTIVE: Cyclosporine A is an immunosuppressive drug that is widely used in organ transplant patients as well as to treat a number of autoimmune conditions. Bone loss is reported as a significant side-effect of cyclosporine A use because this can result in serious morbidity of the patients. As we have shown that cyclosporine A-associated bone loss can also affect the alveolar bone, the purpose of this study was to evaluate the effect of the concomitant administration of alendronate on alveolar bone loss in a rat model. MATERIAL AND METHODS: Forty Wistar rats (10 per group) were given cyclosporine A (10 mg/kg, daily), alendronate (0.3 mg/kg, weekly), or both cyclosporine A and alendronate, for 60 d. The control group received daily injections of sterile saline. The expression of proteins associated with bone turnover, including osteocalcin, alkaline phosphatase and tartrate-resistant acid phosphatase (TRAP), and also the calcium levels, were evaluated in the serum. Analysis of the bone volume, alveolar bone surface, the number of osteoblasts per bone surface and the number of osteoclasts per bone surface around the lower first molars was also performed. RESULTS: The results indicate that cyclosporine A treatment was associated with bone resorption, represented by a decrease in the bone volume, alveolar bone surface and the number of osteoblasts per bone surface and by an increase in the number of osteoclasts per bone surface and TRAP-5b. These effects were effectively counteracted by concomitant alendronate administration. CONCLUSION: It is concluded that concomitant administration of alendronate can prevent cyclosporine A-associated alveolar bone loss.     

正畸力作用下大鼠白细胞介素-6的表达及牙槽骨改建的研究

目的:观察正畸力作用下IL-6在大鼠牙周组织内的表达分布及牙槽骨高度的改变,研究正畸力对牙周组织改建的作用.方法:将30 只SD大鼠随机分为空白对照组和加力组,施加0.49 N近中向正畸力于加力组25 只大鼠的左侧上颌第一磨牙.运用免疫组织化学及组织形态分析法观测各组大鼠上颌第一磨牙加力后0、1、3、5、7、10 d的IL-6表达量及牙槽骨吸收量.结果:加力组大鼠牙周组织内IL-6的表达在受力后第3天达到高峰,之后开始下降;其近中牙槽骨未见明显丧失.结论:正畸力虽可引发局部牙周组织的炎症反应及IL-6等促炎性细胞因子的释放,但具有一定的自限性,不会导致牙周组织的严重破坏和牙槽骨的明显吸收.     

In vivo administration of IL-1β accelerates silk ligature-induced alveolar bone resorption in rats

The effects of recombinant human interleukin-1β (rhIL-1β) on alveolar bone resorptive activity in rats were examined. Continuous administration of rhIL-1β or phosphate-buffered saline (PBS) was given via osmotic pumps for 3, 7 and 14 days to rats with silk ligatures around second maxillary molars. Other animals without ligatures received insertion of pumps containing rhIL-lp or remained untreated. Sections were subject to three different stains:–hematoxylin and eosin (H-E) for histology, acid phosphatase (ACPase) activity for osteoclast detection, and immunohistochemistry using anti-rat monocyte/macrophage monoclonal antibody (ED 1). In addition, body weight, plasma calcium and phosphorus levels were monitored. The mean body weight of rats receiving rhIL-lp was significantly lower (P < 0.05 to P < 0.01) compared with untreated rats throughout the experimental period. On Day 7, plasma calcium and phosphorus levels were significantly lower in rats receiving rhIL-1β than in rats receiving PBS only (P < 0.05). Sections revealed a moderate inflammatory cell infiltrate reaching near the alveolar crest in both groups with ligatures on Day 3. Only rats receiving rhIL-lp exhibited enhancement of inflammatory cell invasion on Days 7 and 14. In rats receiving rhIL-lp with ligatures, numerous resorption lacunae containing ACPase-positive multinucleated giant cells (MNGCs), coinciding with ED1-positive cells, were located on the mesial side of the septum where extensive bone resorption had occurred throughout the experimental period. In animals receiving rhIL-β without ligatures, compared with untreated rats, increased ACPase-positive cells were observed on the mesial side of the septum on Day 3. In animals receiving PBS only, a few ACPase-positive cells were observed confined to the mesial regions where slight bone resorption occurred on Days 7 and 14. These results indicate that the administration of rhIL-1β accelerated alveolar bone destruction in ligature-induced periodontal tissue inflammation over a two-week period.     

Radiographic assessment of photodynamic therapy as an adjunctive treatment on induced periodontitis in immunosuppressed rats

Objective

The aim of this study was to assess radiographically the effect of photodynamic therapy (PDT) as an adjunctive treatment to scaling and root planing (SRP) on induced periodontitis in dexamethasone-induced immunosuppressed rats.

Material and Methods

The animals were divided into 2 groups: ND group (n=60): saline treatment; D group (n=60): dexamethasone treatment. In both ND and D groups, periodontal disease was induced by the placement of a ligature in the left first mandibular molar. After 7 days, ligature was removed and all animals received SRP, being divided according to the following treatments: SRP: saline and PDT: phenothiazinium dye (TBO) plus laser irradiation. Ten animals per treatment were killed at 7, 15 and 30 days. The distance between the cementoenamel junction and the height of the alveolar bone crest in the mesial surface of the mandibular left first molars was determined in millimeters in each radiograph. The radiographic values were analyzed statistically by ANOVA and Tukey''s test at a p value <0.05.

Results

Intragroup radiographic assessment (ND and D groups) showed that there was statistically significant less bone loss in the animals treated with PDT in all experimental periods compared to those submitted to SRP. Intergroup radiographic analysis (ND and D groups) demonstrated that there was greater bone loss in the ND group treated with SRP compared to the D group treated with PDT at 7 and 30 days.

Conclusion

PDT was an effective adjunctive treatment to SRP on induced periodontitis in dexamethasone-induced immunosuppressed rats.     

Protective effects of etoricoxib, a selective inhibitor of cyclooxygenase-2, in experimental periodontitis in rats

BACKGROUND: The purpose of the present study was to evaluate the effect of a potent selective cyclooxygenase-2 (COX-2) inhibitor, etoricoxib, on the prevention of alveolar bone loss in experimental periodontitis induced in rats. METHODS: Ninety Wistar rats were separated into three experimental groups. Cotton ligatures were placed at the gingival margin level of lower right first molars. The rats were randomly assigned to one of the following groups: control received a daily oral dose of 1 ml/kg of saline solution; Eto1 received 6 mg/kg of etoricoxib; Eto2 received 12 mg/kg of etoricoxib. Serum levels of etoricoxib and white blood cells were determined. Standardized digital radiographs were taken after death at 3, 5, 10, 18 and 30 days to measure the amount of bone loss at the mesial root surface of the first molar tooth in each rat. RESULTS: One-way analysis of variance (anova) indicated that groups treated with both doses of etoricoxib had significantly (p < 0.05) less alveolar bone loss when compared to controls. Furthermore, etoricoxib treatment significantly inhibited the leukocytosis observed 3 days after the induction of periodontitis. CONCLUSION: These data provide evidence that systemic therapy with etoricoxib can retard alveolar bone loss in a ligature-induced periodontitis model in rats.     

大鼠颌骨骨皮质切开术后骨小梁三维结构的改变

目的 探索骨皮质切开术后牙槽骨骨小梁的结构改变规律.方法 选取健康Wistar雄性大鼠10只,在其左侧上颌第一臼齿近远中牙槽骨施行骨皮质切开术,右侧不做处理作为对照.分别在手术前,和手术后7、14、21及42天使用活体Micro-CT进行扫描,获得大鼠上颌牙槽骨以及牙齿的影像学数据,并对其进行分析.结果 术后14天大鼠牙槽骨的骨密度显著降低(P＜0.05),而术后42天又显著升高至比术前更高的水平(P＜0.01).各项三维结构的指标均显示先疏松后致密的趋势.结论 大鼠颌骨骨皮质切开术后,骨质疏松发生在术后14天前,以后逐渐致密,到术后42天已达到比术前更致密的水平.     

Nicotine effects on alveolar bone changes induced by occlusal trauma: a histometric study in rats

BACKGROUND: The aim of the present study was to verify nicotine effects on alveolar bone changes induced by occlusal trauma during a periodontitis experimental model in rats. METHODS: Thirty adult male rats were used. The animals were randomly assigned to one of three groups receiving daily intraperitoneal injections: A, nicotine solution (0.44 mg/ml) and occlusal overload; B, saline solution and occlusal overload; or C, saline solution. Rats from groups A and B underwent bilateral amputation of the second and third molar cusps to simulate an occlusal overload. The first molars were then randomly assigned to receive a cotton ligature in the sulcular area, while the contralateral tooth was left unligated. The animals were sacrificed 30 days later. The resected mandibles were processed, and histomorphometric measurements were performed in the alveolar bone adjacent to the furcation area of the first molars. RESULTS: Nicotine enhanced the bone loss induced by occlusal trauma (P<0.001) on the ligated teeth of group A (12.27 +/- 4.4 mm2), when compared to groups B (8.43 +/- 3.51 mm2) and C (4.43 +/- 2.17 mm2). Alveolar bone loss (P<0.01) was also observed in the contralateral teeth of groups A (nicotine + trauma) and B (saline + trauma), when compared to group C (saline only). CONCLUSION: Within the limits of the study, it is concluded that nicotine may influence the alveolar bone changes induced by occlusal trauma by enhancing bone loss.     

Micro‐computerized tomography analysis of alveolar bone loss in ligature‐ and nicotine‐induced experimental periodontitis in rats

Liu Y‐F, Wu L‐A, Wang J, Wen L‐Y, Wang X‐J. Micro‐computerized tomography analysis of alveolar bone loss in ligature‐ and nicotine‐induced experimental periodontitis in rats. J Periodont Res 2010; 45: 714–719. © 2010 John Wiley & Sons A/S Background and Objective: Nicotine reportedly is a risk factor for periodontitis, but accurate data regarding nicotine‐induced alveolar bone loss is lacking. The aim of this study was to quantitatively assess alveolar bone loss in ligature‐ and nicotine‐induced periodontitis in rats using micro‐computerized tomography (micro‐CT). Material and Methods: Thirty‐six adult male rats were treated by placing silk ligatures around the cervixes of the right second maxillary molar; the contralateral tooth was untreated. After ligation, the animals were randomly divided into three groups: group A received intraperitoneal injections of saline solution, group B received 0.83 mg of nicotine/kg/d, and group C received 1.67 mg of nicotine/kg/d. Six animals in each group were killed on days 14 and 28 after ligature placement, and then micro‐CT examinations were conducted. Results: In all groups, bone mineral density (BMD), bone volume fraction (BVF), trabecular number (Tb.N) and trabecular thickness (Tb.Th) values of the ligated sides were significantly lower than those of the unligated sides (p < 0.001), whereas alveolar bone height loss (ABHL) and trabecular separation (Tb.Sp) of the ligated sides were significantly higher than those of the unligated sides (p < 0.001). Compared with the control group, nicotine administration increased the ABHL value and decreased the BMD, BVF and Tb.Th values of both sides in a dose‐dependent manner (p < 0.05). Conclusion: Our results confirmed that ligature could cause significant loss in the trabecula of alveolar bone, and daily administration of nicotine resulted in further bone loss and microstructure deterioration.     

The influence of thyroid hormones on periodontitis-related bone loss and tooth-supporting alveolar bone: a histological study in rats

Background and Objective: Recent studies have pointed to potentially periodontal risk indicators, however no information is available on the impact of changes in thyroid hormone levels on the progression of periodontitis and on the quality of alveolar bone. Thus, the aim of the present study was to evaluate histologically, in rats, the influence of thyroid hormones on the rate of periodontal bone loss resulting from ligature placement and on the quality of tooth‐supporting alveolar bone. Material and Methods: Thirty‐six male Wistar rats were randomly assigned to the following groups: healthy (control, n = 12), hypothyroidism (n = 12) and hyperthyroidism (n = 12). Once alterations were confirmed by total serum levels of triiodothyronine and thyroxine, ligatures were randomly placed around one of the first mandibular molars. Thirty days later, the animals were killed and specimens routinely processed for serial decalcified sections. The parameters assessed were periodontitis‐related bone loss, quality of tooth‐supporting alveolar bone and the number of cells positive for tartrate‐resistant acid phosphatase (TRAP), a marker of bone resorption. Results: At the ligated sites, intergroup analysis revealed that hypothyroidism significantly increased the bone loss resulting from ligature‐induced periodontitis (p = 0.02) and the number of TRAP‐positive cells on the linear surface of bone crest (p = 0.01). In addition, no significant differences were detected regarding the quality of the bone (p = 0.24) or the number of TRAP‐positive cells in the area of the interradicular bone for ligated teeth among the groups (p = 0.17). Conclusion: It may be concluded that decreased serum levels of thyroid hormones may enhance periodontitis‐related bone loss, as a function of an increased number of resorbing cells, whereas the tooth‐supporting alveolar bone seems to be less sensitive to alterations in hormone levels.     

Influence of age on combined effects of cyclosporin and nifedipine on rat alveolar bone

BACKGROUND: There is some evidence showing that cyclosporin A (CsA) and nifedipine (NIF) affect bone metabolism. The purpose of this work was to study the effects of CsA and NIF, given alone or concurrently, on alveolar bone of rats of different ages. METHODS: Rats 15, 30, 60, and 90 days old were treated daily with 10 mg/kg body weight of CsA subcutaneously injected and/or 50 mg/kg body weight of NIF/day given orally for 60 days. Alveolar bone of the first lower molars was morphologically and stereologically evaluated in serial 5 microm bucco-lingual paraffin sections, stained with hematoxylin and eosin. Serum calcium and alkaline phosphatase levels were measured in all animals at the end of the experimental period. RESULTS: Rats treated with CsA or NIF alone or CsA and NIF concurrently showed decreased alveolar bone density. CsA was more effective than NIF. A significant decrease in serum calcium was found only in animals treated with CsA or CsA/NIF. The results were similar regardless of age. CONCLUSIONS: These results indicate that the decrease in the alveolar bone volume in rats caused by CsA and NIF alone or concurrently is not age dependent. Furthermore, NIF (50 mg/kg) did not further increase the loss of alveolar bone volume induced by CsA (10 mg/kg).     

Topical and intermittent application of parathyroid hormone recovers alveolar bone loss in rat experimental periodontitis

Tokunaga K, Seto H, Ohba H, Mihara C, Hama H, Horibe M, Yoneda S, Nagata T. Topical and intermittent application of parathyroid hormone recovers alveolar bone loss in rat experimental periodontitis. J Periodont Res 2011; 46: 655–662. © 2011 John Wiley & Sons A/S Background and Objective: Periodontitis is characterized by periodontal tissue inflammation and alveolar bone loss. The intermittent administration of parathyroid hormone (PTH), a major regulator of bone remodeling, has been demonstrated to stimulate osteoblastic activity. Although the systemic administration of PTH has been reported to protect against periodontitis‐associated bone loss, the effect of the topical administration of PTH is unclear. In this study, the effect of intermittent administration of PTH on osteoblastic differentiation was examined in cultured calvaria cells and then the effect of topical and intermittent administration of PTH was determined by measuring the recovery of alveolar bone loss after inducing experimental periodontitis in rats. Material and Methods: Alkaline phosphatase activity and bone nodule formation were measured in fetal rat calvaria cells. Experimental periodontitis was induced by placing nylon ligature around rat maxillary molars for 20 d. After ligature removal (day 0), PTH was topically injected into buccal gingiva three times a week for 10 wk. Micro‐computed tomography analysis and histological examination were performed on days 35 and 70. Results: Intermittent exposure of PTH in calvaria cells increased alkaline phosphatase activity and bone nodule formation by 1.4‐ and 2.4‐fold, respectively. Ligature procedures induced marked alveolar bone loss around the molars on day 0 and greater bone recovery was observed in the PTH‐treated rats on day 70. An increase in osteoid formation on the surface of alveolar bone was detected in the PTH‐treated rats. Conclusion: Intermittent treatment with PTH stimulated osteoblastic differentiation in fetal rat calvaria cell cultures, and topical and intermittent administration of PTH recovered alveolar bone loss in rat experimental periodontitis.     

环孢素 A 对大鼠牙槽骨内 DMP1 C 末端和 OPN 表达的影响

目的：观察环孢素A（cyclosporinA,CsA）对大鼠牙槽骨内牙本质基质蛋白1（dentinmatrixprotein,DMP1）C末端和骨桥蛋白（osteopontin,OPN）表达的影响。方法：30只7周龄健康雄性Wistar大鼠,随机等分为对照组和实验组,每组再随机等分为20d、30d和40d3个亚组,实验组大鼠喂饲CsA（30mg／k·d）。免疫组化法染色下颌第一磨牙颊舌向石蜡切片,光镜下观察DMP1C末端和OPN在牙槽骨内的表达情况。结果：与对照组大鼠比较,实验组大鼠牙槽骨内DMP1C末端表达明显下调,OPN表达明显上调;在本实验周期内,上述变化随实验时间的延长而加重。结论：CsA影响大鼠牙槽骨内矿化相关非胶原蛋白DMP1C末端和OPN的表达,推测CsA可能抑制大鼠牙槽骨的矿化。     

大鼠牙龈退缩模型的建立

目的:在大鼠上颌磨牙区建立牙龈退缩模型。方法:使用牙科涡轮机和慢速手机,磨除大鼠右侧(实验侧)上颌第一磨牙近中端牙槽骨,缝合牙龈及黏膜组织。2月后处死大鼠,取其上颌双侧磨牙及牙周组织,分别测量从第一磨牙牙合平面远中边缘到第一磨牙近中牙龈上端距离。结果:实验侧牙龈相对对照侧牙龈有明显退缩(P<0.01)。结论:牙龈退缩是临床常见症状,牙龈退缩的大鼠动物模型建立成功,为进一步治疗牙龈退缩提供了更好的动物实验模型。较既往实验中所用的大型动物,节约了实验室空间、实验费用,便于大量实验的开展。     

增龄因素对鼠正畸牙齿移动中牙周组织骨保护素（OPG）表达的影响

目的 比较在正畸牙齿移动中幼年鼠和成年鼠牙周组织骨保护素(osteoprotegerin,OPG)信使RNA(mRNA)表达的不同,以探讨增龄因素影响正畸骨改建的分子机制。方法以4周(幼年鼠)和24周(成年鼠)雄性大鼠为实验动物,牵引左上第一磨牙近中移动为正畸牙齿移动模型,原位杂交检测牙周膜组织OPG mRNA的表达。结果 1.幼年鼠正畸牙齿移动中加力后3小时张力侧近牙槽骨表面可见OPG表达阳性细胞排列;与幼年鼠相比,成年鼠加力后牵张侧牙周膜细胞的OPG mRNA表达没有明显改变。2.幼年鼠加力后6小时开始压力侧即可观察到破骨细胞的数目明显增多,成年鼠加力后,压力侧加力24小时可见破骨细胞;无论幼年和成年鼠压力侧牙周膜细胞的OPG mRNA表达在加力前后均未见明显改变。结论 增龄因素使牙周组织内OPG表达明显增强;成年牙周组织中较强的OPG表达可能与成人正畸出现的牙槽骨吸收、牙齿移动迟缓相关。