Topical administration of simvastatin recovers alveolar bone loss in rats

Background and Objective:  Simvastatin, a cholesterol-lowering drug, has been reported to show anabolic effects on bone metabolism. We examined the effects of simvastatin in vitro using cultured rat calvaria cells and in vivo using periodontitis-induced rats.
Material and Methods:  Alkaline phosphatase activity and bone nodule formation were measured in cultured rat calvaria cells. Nylon ligature was placed around the maxillary molars of Fischer male rats for 20 d to induce alveolar bone resorption. After ligature removal, simvastatin was topically injected into the buccal gingivae for 70 d and then microcomputed tomography and histological examinations were performed.
Results:  Simvastatin maintained high alkaline phosphatase activity and increased bone nodule formation in rat calvaria cells in a dose-dependent manner, showing that simvastatin increased and maintained a high level of osteoblastic function. Microcomputed tomography images revealed that treatment with simvastatin recovered the ligature-induced alveolar bone resorption, showing a 46% reversal of bone height. Histological examination clarified that low-mineralized alveolar bone was formed in simvastatin-treated rats.
Conclusion:  These findings demonstrate that simvastatin has the potential to stimulate osteoblastic function and that topical administration of simvastatin may be effective for the recovery of alveolar bone loss in rats.     

类骨质羟磷灰石和自体骨修复兔下颌骨临界性骨缺损的研究

目的探讨类骨质羟磷灰石（SBR）的生物相容性,并探讨该替代材料和自体骨混合修复骨缺损的生物学特性。方法选用新西兰大白兔,在实验动物双侧下颌骨内侧形成10 mm×10 mm×2 mm大小的临界性缺损,左侧骨缺损按照1∶1比例植入SBR和自体骨,右侧骨缺损内分别植入自体骨或缺如,术后2、4、8周取标本,进行大体标本、X线、组织学和Masson新三色染色法的形态学分析。结果生物替代物具有良好的生物相容性,与自体骨混合能有效地促进骨缺损的修复愈合。骨髓细胞很容易在该材料表面黏附,自体骨的加入更有利于新骨长入材料的孔隙中,分化增殖,形成骨基质,并钙化成熟。结论SBR是一种良好的骨替代材料,自体骨的加入更有利于早期成骨和替代材料的自我改建的完成。     

Bone healing pattern in surgically created circumferential defects around submerged implants: an experimental study in dog

Objective: To describe the healing of marginal defects below or above 1 mm of dimension around submerged implants in a dog model. Material and methods: In 12 Labrador dogs, all mandibular premolars and first molars were extracted bilaterally. After 3 months of healing, full‐thickness flaps were elevated in the edentulous region of the right side of the mandible. Two recipient sites were prepared and the marginal 5 mm were widened to such an extent to obtain, after implant installation, a marginal gap of 0.5 mm at the mesial site (small defect) and of 1.25 mm at the distal site (large defect). Titanium healing caps were affixed to the implants and the flaps were sutured allowing a fully submerged healing. The experimental procedures were subsequently performed in the left side of the mandible. The timing of the experiments and sacrifices were planned in such a way to obtain biopsies representing the healing after 5, 10, 20 and 30 days. Ground sections were prepared and histomorphometrically analyzed. Results: The filling of the defect with newly formed bone was incomplete after 1 month of healing in all specimens. Bone formation occurred from the base and the lateral walls of the defects. A larger volume of new bone was formed in the large compared with the small defects. Most of the new bone at the large defect was formed between the 10‐ and the 20‐day period of healing. After 1 month of healing, the outline of the newly formed bone was, however, located at a similar distance from the implant surface (about 0.4 mm) at both defect types. Only minor newly formed bone in contact with the implant, starting from the base of the defects, was seen at the large defects (about 0.8 mm) while a larger amount was detected at the small defects (about 2.2 mm). Conclusion: Marginal defects around titanium implants appeared to regenerate in 20–30 days by means of a distance osteogenesis. The bone fill of the defects was, however, incomplete after 1 month. To cite this article:
Rossi F, Botticelli D, Pantani F, Pereira FP, Salata LA, Lang NP. Bone healing pattern in surgically created circumferential defects around submerged implants: an experimental study in dog.
Clin. Oral Impl. Res 23 , 2012; 41–48.
doi: 10.1111/j.1600‐0501.2011.02170.x     

Healing patterns of critical size bony defects in rats after grafting with bone substitutes soaked in recombinant human bone morphogenetic protein-2: histological and histometric evaluation

The aim of the study was to evaluate the effect of different bone substitutes soaked in recombinant human bone morphogenetic protein-2 (rhBMP-2) on the healing of critical size defects in calvarial bone. Defects were created in 24 Sprague Dawley rats. The rhBMP-2 was diluted to obtain a final concentration of 0.2 mg/ml. Rats were divided into four groups and treated as follows: in the first group the defect was filled with anorganic bovine bone mineral (ABBM) and rhBMP-2, the second group was treated with freeze-dried bone allograft (FDBA) and rhBMP-2, and the third group was treated with autogenous bone (AUTO). In the control group the defects were left untreated. Animals were killed after 8 weeks and calcified histological sections prepared. Histometric measurements showed that mean (SD) bone formation was 4.00 (1.69) mm² in the ABBM group, 2.56 (1.06) mm² in the FDBA group, and 2.30 (0.34) mm² in the AUTO group. The difference between the ABBM group and the other 3 groups was significant (p < 0.0001) with a mean bone formation of 0.82 (0.25) mm² in the control group. There was no significant difference between the FDBA and the AUTO groups (p = 0.96). Within the limits of this study we concluded that the addition of rhBMP-2 to bone substitutes was efficacious in regenerating bone in critical size bone defects in calveria in rats.     

Association of hyaluronic acid with a collagen scaffold may improve bone healing in critical-size bone defects

Objectives: To evaluate the effects of a 1% hyaluronic acid (HA) gel in combination with an absorbable collagen sponge (ACS) in the healing of critical‐size calvaria defects in rats. Material and methods: Thirty‐two adult Wistar rats were used. Two 5‐mm‐diameter critical‐size defects were created and the treatments were randomly distributed as follows: (1) 1% HA; (2) 1% HA gel‐soaked ACS; (3) control (blood clot); and (4) ACS. The animals were sacrificed 60 days post‐surgery, when biopsies were collected and processed for histology and histometric analysis. Bone fill was measured as the difference between the initial and the final defect sizes. Non‐parametric tests were used to analyze differences between treatments (α=1%) and a t‐test for body weight gain in each treatment group (α=5%). Results: Histological analysis showed bone formation on the edges of the defects, although very limited, and a thin layer of connective tissue occupying the midportion of the defects in the control and the ACS groups. Defects filled with a 1% HA gel and 1% HA gel+ACS had a thicker layer of connective tissue and more new bone formed in the margins of the defects. Linear histometric measures showed no significant differences in the initial defect sizes between the groups (P>0.05). The association 1% HA gel+ACS (0.96 ± 0.14 mm) had significantly greater bone fill than the control (0.5 ± 0.02 mm) and ACS (0.56 ± 0.05 mm)‐treated groups (P=0.0043 and 0.0173, respectively). Treatment with a 1% HA gel (0.7 ± 0.14 mm) showed no significant differences when compared with the other treatments. Conclusion: Within the limits of this study, a 1% HA gel associated with a collagen scaffold can improve new bone formation in critical‐size defects. However, this treatment never resulted in complete closure of the defects and healing in the major portion of the defects was characterized by fibrous tissue. To cite this article:
de Brito Bezerra B, Brazão MAM, de Campos MLG, Casati MZ, Sallum EA, Sallum AW. Association of hyaluronic acid with a collagen scaffold may improve bone healing in critical‐size bone defects.
Clin. Oral Impl. Res. 23 , 2012; 938–942
doi: 10.1111/j.1600‐0501.2011.02234.x     

MicroCT定量研究去势大鼠颌骨与胫骨的骨改变

目的:应用MicroCT对Sprague-Dawley(SD)雌性大鼠去除双侧卵巢三个月后的下颌骨和胫骨进行对比研究。方法:分别从假手术对照(Sham)组和卵巢切除骨质疏松(OVX)组各取大鼠8只。将全部大鼠深度麻醉后处死。取一侧下颌骨和胫骨,去净软组织。行MicroCT检查、骨组织病理学研究。所得数据经SPSS13.0统计分析。结果:大鼠去除双侧卵巢3月后,经MicroCT检查发现,OVX组大鼠胫骨:骨小梁数目减少,排列稀疏,骨小梁断裂;骨小梁面积比和体积比、厚度和数目,骨矿含量和骨体积密度等均较Sham组显著降低,骨小梁分离度增加,P<0.05。OVX组大鼠下颌骨:骨组织体积比、骨小梁厚度和单位体积骨小梁数目,均比Sham组升高,骨小梁分离度较Sham组降低,P<0.05。与胫骨改变比较,结果完全相反。另外,大鼠下颌骨的三维骨矿含量和骨体积密度也升高,P<0.05。骨组织切片病理学观察:Sham组胫骨松质骨呈条索状,骨小梁相互连接成网;下颌骨松质骨较致密,呈板状。OVX组胫骨骨小梁变细,分离度增大,新生骨基质减少。磨牙下方松质骨骨髓腔增大,牙槽突新生骨基质减少。结论:SD雌性大鼠切除卵巢3月后,下颌骨与胫...     

Histomorphometric and mineral degradation study of Ossceram: a novel biphasic B-tricalcium phosphate, in critical size defects in rabbits

Objective: To carry out a histomorphometric analysis of a new highly porous (95%) biphasic calcium phosphate (hydroxyapatite 60%/B‐tricalcium phosphate 40%), used to fill critical size defects in rabbit tibiae, supplementing histomorphometric findings with radiographic thermal imaging, EDX analysis and Ca/P ratio mapping at different time stages. Materials and methods: Two critical size defects of 6 mm diameter were created in both tibiae of 21 New Zealand rabbits, test group (Ossceram^®) and control group. Histomorphometric, radiographic thermal imaging, EDX and element mapping analysis were performed at 15, 30 and 60 days after graft insertion. Results: Histomorphometric analysis at 30 days showed more new bone formation in defects filled with Ossceram^® 4.41 ± 0.23 mm than the test group 1.94 ± 0. 28 mm (P<0.05). Element analysis revealed higher percentages of Ca (42.33 ± 2.8%) and P (1.3 ± 0.8%) in the test group than in the control group (P<0.05). Element mapping showed that Ca and P were concentrated in medullar and cortical zones in the test group but were concentrated only in cortical zones in the control group. Test group histomorphometry at 60 days showed complete closure of the cortical defect 5.37 ± 0.32 mm more than the control group 2.3 ± 0.54 mm. There was no cortical defect closure or medullar bone formation in the control group (P<0.05). Element analysis revealed higher percentages of Ca (32.26 ± 21.7%) and P (1.5 ± 0.3%) in the test group than in the control group (P<0.05). Conclusion: Defects of a critical size in a rabbit tibia model can be sealed using a highly porous biphasic calcium phosphate; this supports new bone formation, creates a bridge between borders and facilitates bone ingrowth. Furthermore, this study observed partial dissolution of the mineral phase of the graft material and its incorporation into the surrounding bone. Radiographic thermal imaging may be used to supplement histological and chemical analyses.     

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目的探讨辛伐他汀对糖尿病大鼠种植体周围骨组织中骨形态发生蛋白-2(BMP-2)表达的影响及临床意义。方法 2010年5—8月在山西医科大学取成年雄性SD大鼠36只,适应性喂养1周无异常后,随机分为A、B1、B23组,每组12只。A组予腹腔内注射柠檬酸盐缓冲液,B1、B2组按50mg/kg体重剂量予腹腔内注射链尿佐菌素(STZ),建立糖尿病大鼠模型。成模后,在3组大鼠胫骨近骺端种植纯钛种植体。B2组大鼠每日予辛伐他汀5mg/kg体重灌服,A、B1两组大鼠每只每日灌服生理盐水1.5mL。灌胃12周后,处死动物,采用免疫组化方法检测种植体周围骨组织中BMP-2的表达。结果 B2组BMP-2阳性细胞比例明显高于B1组,差异有统计学意义(P<0.01)。结论辛伐他汀能使糖尿病大鼠骨组织BMP-2表达增强,改善骨代谢,有促进种植体骨结合的作用。     

组织工程骨修复颅骨极限缺损种子细胞归宿的探讨

目的：检测纳米羟基磷灰石复合胶原／聚乳酸材料（nHAC／PLA,nano-hydroxyapatite／collagen／Polyacticacid）与骨髓基质细胞（BMSCs,bone marrow stroma cells）在体外复合构建的组织工程骨修复兔颅骨极限缺损的能力,并探讨种子细胞的归宿。方法：将圆盘状nHAC／PLA与BrdU标记的自体BMSCs复合后,植入新西兰大白兔颅骨直径1．5cm全层缺损中。设自体髂骨组、空白对照组及nHAC／PLA组,术后8w、16w通过X线片、HE染色、Masson’s三色法染色、荧光组织学和免疫组织化学染色,观察比较颅骨缺损的修复情况及种子细胞的归宿。结果：nHAC／PLA＋自体BMSCs组修复颅骨缺损的能力强,与自体髂骨组类似,nHAC／PLA组材料修复骨缺损的能力较弱,但强于空白对照组,组织工程骨的成骨细胞由植入的种子细胞演化而来。结论：nHAC／PLA复合自体BMSCs具有良好的修复骨缺损能力。     

干细胞因子在大鼠下颌骨缺损修复中的表达研究

目的:探讨在SD大鼠下颌骨临界性骨缺损(critical size bone defect,CSD)与自愈性骨缺损修复过程中,各时相点干细胞因子(stem cell factor,SCF)的表达情况。方法:①分别在36只SD大鼠双侧下颌骨的下颌角部制造临界性骨缺损(直径5 mm)和自愈性骨缺损(直径2 mm)模型,实验动物分为6组,在术后第1、3、5、7、14、21天分别处死;②利用免疫组织化学方法检测骨缺损区各时相点SCF的表达情况;③利用Western印迹法检测骨缺损区各时相点SCF存在与否,并进行半定量分析。结果:成功构建了大鼠双侧下颌骨的临界性骨缺损和自愈性骨缺损模型。免疫组织化学结果显示,骨缺损愈合的各时相点SCF均有较高的表达,但SCF在临界性骨缺损组各时相点的表达,均低于自愈性骨缺损组。结论:SCF在骨缺损修复中发挥重要的作用。     

辛伐他汀对去势大鼠骨生长代谢的影响

目的:观察辛伐他汀对去势大鼠骨密度和骨生长代谢的作用。方法:40只雌性SD大鼠随机分成4组,正常对照假手术组(Sham)-A,单纯去势组(OVX)-B,去势雌激素治疗组-C;去势辛伐他汀治疗组-D。术后第30天,C组以体质量每100g每天给0.1mg尼尔雌醇灌胃,每周1次,持续12周。D组以辛伐他汀5mg/(kg·d)灌胃,连续服用1周,停2周,再服用1周,间断持续12周。用药12周后,所有大鼠被处死采取胫骨标本,处死前第12和第4天进行四环素双标记。标本行不脱钙骨切片,硝酸银和VonKossa染色,骨形态计量学方法检测各治疗方法对胫骨近心端干骺的作用效果。结果:单纯去势组(OVX)-B与对照假手术组(Sham)-A相比,其胫骨有明显的骨质疏松表现。与OVX相比,雌激素组、辛伐他汀组去势大鼠胫骨骨形态计量学静态参数%Tb.Ar、Tb.N,Tb.Sp有明显差异(P<0.01)。辛伐他汀组的动态骨形成参数%L.Pm、MAR、BFR/BV、%O.Pm及荧光双标间隔均明显高于其他各组(P<0.01),骨吸收参数Oc.N、%E.Pm低于单纯去势组,但高于雌激素组和假手术组(P<0.01),雌激素组骨吸收参数Oc.N、%E.Pm相对单纯去势组显著下降(P<0.01)。结论:辛伐他汀能降低大鼠去势后骨转换,促进骨的生长,并能抑制骨的吸收作用。     

The use of human hypertrophic chondrocytes-derived extracellular matrix for the treatment of critical-size calvarial defects

Objectives: To evaluate the effect of immortalized hypertrophic chondrocytes extracellular matrix (HCM) with or without the use of guided bone regeneration (GBR) on the healing of critical‐size calvarial defects. Material and methods: In 42 rats, 5 mm critical‐size calvarial defects were surgically created. The animals were randomly allocated to six groups of seven rats each: Group A1: one defect was left untreated (control), while the contralateral defect was covered by a double non‐resorbable membrane (GBR). Group B1: one defect was filled with calcium phosphate cement (CP), while the contralateral defect was treated with GBR and CP. Group C1: one defect was filled with a mixture of CP and HCM, while the contralateral defect was treated with GBR and CP+HCM. The healing period for all three groups was 30 days. The remaining three groups were treated in a similar manner but the healing period was 60 days. Five animals from each group were evaluated by maceration and two animals were analysed histologically. Results: At 30 days, all the control‐treated defects did not present complete closure. When GBR was applied alone or combined with CP, 3/5 and 5/5 defects, respectively, presented complete closure. At 60 days, one defect from the control group presented complete closure. All the defects treated with GBR alone presented complete closure, whereas the combined use of GBR with CP or CP+HCM resulted in 4/5 and 3/5 defects with complete closure, respectively. The only treatment modality that did not present any specimen with defect closure at both 30 and 60 days was the combination of CP+HCM. The histological analysis indicated that when GBR was not used alone, the healing consisted of an amorphous acellular structure and loose granulation tissue, which, even though clinically resembled hard tissue, did not demonstrate the histological characteristics of bone. Conclusion: The predictability of bone formation in critical‐size defects depends mainly on the presence or absence of barrier membranes. The combined use of GBR with calcium phosphate alone or in combination with immortalized human HCM did not enhance the potential for osseous healing provided by the GBR procedure. To cite this article:
Donos N, Graziani F, Mardas N, Kostopoulos L. The use of human hypertrophic chondrocytes‐derived extracellular matrix for the treatment of critical‐size calvarial defects.
Clin. Oral Impl. Res. xx , 2011; 000–000.
doi: 10.1111/j.1600‐0501.2010.02120.x