Osseous reaction to implantation of two endodontic cements: Mineral trioxide aggregate (MTA) and calcium enriched mixture (CEM)

Aim: The aim of the present in vivo study was to determine bone tissue reaction to calcium enriched mixture (CEM) and mineral trioxide aggregate (MTA) using a rat femur model. Study Design: Sixty-three rats were selected and randomly divided into three groups of 21 each [experimental groups (n=15), control (n=6)]. Implantation cavities were prepared in each femoral bone and randomly filled with the biomaterials only in the experimental groups. The animals in three groups were sacrificed 1, 4, and 8 weeks postoperatively. Histologic evaluations comprising inflammation severity and new bone formation were blindly made on H&E-stained decalcified 6-µm sections. Results: At 1, 4, and 8 weeks after implantation number of inflammatory cells had decreased in the CEM, MTA and control groups, respectively, with no statistically significant differences. Conversely, new bone formation had increased in all the experimental and control groups, without statistically significant differences. Conclusion: The results suggest that biocompatibility of MTA, as gold standard, and CEM cement as a new endodontic biomaterial are comparable Key words:Endodontics, MTA,CEM, osseous reaction.     

载辛伐他汀PLGA/CPC支架材料复合BMSCs修复大鼠颅骨缺损的实验研究

目的:探讨载辛伐他汀PLGA/CPC支架材料复合骨髓间充质干细胞(BMSCs)构建组织工程骨,修复大鼠颅骨临界尺寸骨缺损的可行性以及效果。方法:24只雄性大鼠随机均分为3组;在大鼠颅骨人字缝两侧各做一直径5 mm的骨缺损。每组16个骨缺损再随机分为:载辛伐他汀PLGA/CPC/BMSCs(Brdu标记的BMSCs)组(n=4);载辛伐他汀PLGA/CPC组(n=4);单纯PLGA/CPC组(n=4)以及空白对照组(n=4)。术后4、8、12周取标本分别进行大体观察,HE染色及免疫组织化学染色来评价骨再生情况。结果:术后4、8、12周组织学观察表明载辛伐他汀PLGA/CPC/BMSCs组的成骨质量和速度明显优于其他3组,免疫组化结果显示载辛伐他汀PLGA/CPC/BMSCs组骨钙素(OC)阳性表达IOD值明显高于其他3组。结论:载辛伐他汀PLGA/CPC支架材料复合BMSCs可以诱导大鼠颅骨临界尺寸骨缺损内的新骨形成,成骨质量优于其他3组,而且可以明显缩短骨愈合时间。     

Cytotoxic effect of MTA and CEM cement in human gingival fibroblast cells. Scanning electronic microscope evaluation

In this ex-vivo study, we assessed the adhesion of human gingival fibroblast (HGF) to mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement using a scanning electronic microscope (SEM). Test biomaterials were prepared and inserted in polyethylene wells (n = 18). Glass coverslips were used for control groups. HGFs were seeded in the glass coverslips, MTA and CEM. For the positive-control group, distilled water was added to the medium; the samples were observed with SEM at one, three and seven-day intervals. Normal cell morphology was observed in the negative controls. In the positive controls, round cells with rougher surfaces were seen; these cells showed few attachments to the glass coverslip. HGFs spread and adhered similarly on MTA and CEM by forming a monolayer of flat cells; there were no statistical differences between these two experimental groups. HGF cells displayed a favorable biologic response in contact with MTA and CEM. This demonstrates non-cytotoxicity of CEM as a novel endodontic biomaterial.     

Repair of furcal perforation using a new endodontic cement

The aim of this study was to compare the histologic response elicited by repairing furcal perforations with mineral trioxide aggregate (MTA) and a new endodontic material in the name of “calcium enriched mixture (CEM) cement” in dogs’ teeth. Thirty-four premolars were randomly divided into four groups: MTA (n = 15), CEM (n = 15), positive, and negative controls (n = 4). Root canal therapy were carried out; perforations were made, and the furcation areas were then repaired with MTA or CEM cement. The animals were sacrificed after 3 months. The teeth and their adjacent structures were processed and stained with hematoxylin and eosin stain for histological evaluation. Chi-square test was used to evaluate hard tissue formation, and Mann–Whitney U test was used for the histological evaluation of inflammation. Specimens in positive controls showed severe inflammatory infiltration, prominent granulation tissue, and epithelial proliferation; negative controls demonstrated normal periodontal ligament without inflammatory reactions. Hard tissue formation was observed in all the specimens of the two experimental groups. In inflammatory evaluation, mild inflammation was detected in the experimental groups, and no statistically significant differences were observed between them. MTA and CEM cement showed similar favorable biological response in furcation perforation repair, especially in inducing the formation of cementum-like hard tissue.     

Comparison of the sealing ability of mineral trioxide aggregate and Portland cement used as root-end filling materials

Inadequate apical seal is the major cause of surgical endodontic failure. The root-end filling material used should prevent egress of potential contaminants into periapical tissue. The purpose of this study was to compare the sealing ability of four root-end filling materials: white mineral trioxide aggregate (MTA), gray MTA, white Portland cement (PC) and gray PC by dye leakage test. Ninety-six human single-rooted teeth were instrumented, and obturated with gutta-percha. After resecting the apex, an apical cavity was prepared. The teeth were randomly divided into four experimental groups (A: white MTA, B: gray MTA, C: white PC and D: gray PC; n = 20) and two control groups (positive and negative control groups; n = 8). Root-end cavities in the experimental groups were filled with the experimental materials. The teeth were exposed to Indian ink for 72 hours. The extent of dye penetration was measured with a stereomicroscope at 16× magnification. The negative controls showed no dye penetration and dye penetration was seen in the entire root-end cavity of positive controls. However, there was no statistically significant difference among the four experimental groups (P > 0.05). All retrograde filling materials tested in this study showed the same microleakage in vitro. Given the low cost and apparently similar sealing ability of PC, PC could be considered as a substitute for MTA as a root-end filling material.     

纳米羟基磷灰石复合胶原材料负载骨髓基质干细胞修复颅骨极限缺损的实验研究

目的:探讨纳米羟基磷灰石复合胶原材料(nHAC)负载骨髓基质干细胞作为组织工程骨在修复颅骨极限缺损中的作用。方法:20只新西兰大白兔随机分为复合细胞组、单纯材料组、空白对照组。复合细胞组取自体骨髓基质干细胞并扩增诱导培养后通过负压抽吸及细胞基质膜包裹将细胞与材料复合。材料植入颅骨缺损后8周取材,行大体、X线、组织学观察及灰量测量来研究它们的骨修复能力。结果:复合细胞组成骨能力最强,且材料边缘及内部均有较好的成骨,单纯材料组有部分成骨,空白对照组未修复骨缺损。结论:纳米羟基磷灰石复合胶原材料负载骨髓基质干细胞后是一种较为理想的骨替代材料。     

Effect of platelet-rich plasma on bone healing of autogenous bone grafts in critical-size defects

Aim: This study histologically analysed the effect of autogenous platelet-rich plasma (PRP), prepared according to a new semiautomatic system, on healing of autogenous bone (AB) grafts placed in surgically created critical-size defects (CSD) in rabbit calvaria.
Material and Methods: Sixty rabbits were divided into three groups: C, AB and AB/PRP. A CSD was created in the calvarium of each animal. In Group C (control), the defect was filled by blood clot only. In Group AB (autogenous bone graft), the defect was filled with particulate autogenous bone. In Group AB/PRP (autogenous bone graft with platelet-rich plasma), it was filled with particulate autogenous bone combined with PRP. All groups were divided into subgroups ( n =10) and euthanized at 4 or 12 weeks post-operatively. Histometric and histologic analyses were performed. Data were statistically analysed ( anova , t -test, p <0.05).
Results: Group C presented significantly less bone formation compared with Group AB and AB/PRP in both periods of analysis ( p <0.001). At 4 weeks, Group AB/PRP showed a statistically greater amount of bone formation than Group AB (64.44 ± 15.0% versus 46.88 ± 14.15%; p =0.0181). At 12 weeks, no statistically significant differences were observed between Groups AB and AB/PRP (75.0 ± 8.11% versus 77.90 ± 8.13%; p >0.05). It is notable that the amount of new bone formation in Group AB/PRP at 4 weeks was similar to that of Group AB at 12 weeks ( p >0.05).
Conclusion: Within its limitation, the present study has indicated that (i) AB and AB/PRP significantly improved bone formation and (ii) a beneficial effect of PRP was limited to an initial healing period of 4 weeks.     

两种材料修复比格犬髓室底穿孔的效果评价

目的:评价MTA和光固化氢氧化钙修复比格犬牙齿髓室底穿孔的效果.方法:3只成年比格犬的36颗前磨牙根管治疗后做髓室底穿孔模型,随机分为两组,分别采用MTA和光固化氢氧化钙修复穿孔.另外24颗磨牙根管治疗后随机分为阳性和阴性对照组,阳性对照组做髓室底穿孔模型后以聚氯乙烯膜覆盖穿孔,阴性对照组不穿孔.分别于术后1,4,12...     

Distraction osteogenesis after irradiation in rabbit mandibles

The aim of this study was to investigate the influence of irradiation on the formation of bone after distraction osteogenesis in rabbit mandibles. Sixteen rabbits were randomly divided into 3 groups: one was given 50Gy (n=6), one was given 60Gy (n=6), and one acted as a control group (n=4). One month after irradiation, the distractors were inserted. The control group was not irradiated. After a latency period of 8 days, distraction was activated at a rate of 0.4mm twice a day. The mandibles were harvested 6 weeks after consolidation. The specimens and histological examination showed good formation of bone. Histological slides stained with haematoxylin and eosin confirmed that the regeneration was bone. The bony trabeculae of the control group were much better than those of the irradiated groups. However, the nuclei of osteocytes were round and the osteoblasts around the trabeculae were columnar or cubic in shape in the irradiated groups. Osteoid was present in the dense fibrous connective tissue. There were significant differences in the surface:volume ratio of areas of bony trabeculae between the control and both experimental groups (p=0.010 and p=0.001), but there was no significant difference between the 50Gy and 60Gy groups. The results suggested that preoperative radiation prevented optimal regeneration of bone. However, the microscopic appearance of osteocytes and osteoblasts and the osteoid in the dense fibrous connective tissue in both irradiated groups showed that osteogenesis was still active and in progress. These findings may indicate that bone formation had only been delayed. The evidence was similar for both 50Gy and 60Gy.     

下颌骨牵引成骨与直接延长术的组织学比较

目的：通过对下颌骨牵引成骨与直接延长术组织学变化的对比研究分析，探讨牵引成骨的成骨机制。方法：24只狗随机分为牵引成骨组和直接延长组各12只，用HE染色光镜组织学检查方法分别观察牵引第6天、牵引后固定2、8周不同时期的两组组织学变化。结果：牵引组在牵引后固定第8周，牵引区几乎完全由新生的骨组织连接修复，成骨方式是以膜内成骨为主，伴有少量的软骨内成骨；而直接延长组仅早期在两骨断端附近可见活跃的膜内成骨，两周以后则以软骨内成骨为丰，中间区域仍为大量的纤维结缔组织，8周以后成骨量增加．但中央仍为软骨组织和纤维组织间隔。结论：牵引成骨以膜内成骨为主，达到良好的骨愈合，直接延长成骨效果不稳定，容易导致成骨不良。     

牵张成骨矫治腭裂的激光共聚焦荧光定量分析

目的：利用激光共聚焦显微镜与计算机辅助荧光定量分析，研究牵张成骨术矫治腭裂新骨生成随时间间期不同的动态变化趋势，为临床矫治腭裂应用提供理论与实验依据。方法：以家猫20只为实验对象。其中18只动物建立人工腭裂实验模型。实验组（动物15只）：应用牵张成骨术，以0．4mm×2次／d的速率牵张整复封闭其腭部组织缺损。术后第2、4、6、8及12周前6d以四环素肌注标记（30mg／kg）后各取材3只动物，标本制片后激光共聚焦显微镜观察荧光沉积并进行计算机定量分析，结果与实验对照组（动物3只）及空白对照组（动物2只）对比。结果：实验组不同时间间期标本的荧光强度平均值及其总量，显示出明确的动态变化规律，自2周组起，成骨活动明显活跃，到4周组达到顶峰，至8、12周组逐渐减弱，但仍显著高出无明显荧光沉积的空白和试验对照组。结论：应用牵张成骨术移动骨运送盘封闭组织缺损，牵张间隙逐渐被膜内成骨新骨生成修复，恢复了骨连续性。随时间间期的延长，新骨逐渐改建成熟。成骨活动呈现短期达到高峰后，逐步减弱的动态变化规律。     

新型聚乳酸共聚物修复兔下颌骨缺损的实验研究

目的:研究一种新型的聚乳酸鄄聚乙二醇(PLA鄄PEG)共聚物作为细胞因子的载体修复兔下颌骨缺损。方法:新型聚乳酸共聚物(孔隙率为88.7%左右,孔径150～250μm,分子量35973u)和细胞因子(骨形成蛋白、碱性成纤维细胞生长因子)复合后,分为实验组Ⅰ(PLA鄄PEG/BMP)、实验组Ⅱ(PLA鄄PEG/BMP/bFGF)和对照组(PLA鄄PEG)三组,分别植入27只雌性新西兰白兔的右侧下颌体部预制直径5mm,深3mm的骨缺损。术后2周、4周和8周,对实验标本进行大体、X线、组织学观察及计算机图像分析观察。结果:实验期间各组实验位点均未发生炎症和排异反应,各组创口愈合均良好,成骨活跃。2周时实验组Ⅱ成骨量最多,实验组Ⅰ其次,对照组最少,差异在统计学上有显著性意义;4周时实验组Ⅱ成骨量最多,其余两组成骨量差异不大;8周时各组的成骨量的差异在统计学上无显著性意义。结论:新型的PLA鄄PEG共聚物呈现良好的生物相容性和骨引导性,复合BMP后早期通过BMP骨诱导作用对骨再生具有较明显的促进作用,bFGF在与PLA鄄PEG和BMP复合后通过其促进毛细血管增殖的效应而对PLA鄄PEG和BMP有协同增强作用。     

腺相关病毒介导的骨形态发生蛋白7基因促种植体周骨缺损修复的实验研究

目的观察载bmp7基因的腺相关病毒（rAAV- BMP7）复合Bio- Oss的基因治疗方法对种植体周骨缺损修复的影响。方法体外构建载bmp7基因的腺相关病毒,并与Bio- Oss复合。6只雄性新西兰大白兔双侧胫骨植入种植体,并制备直径8 mm、深4 mm的种植体周骨缺损,A组骨缺损区填入rAAV- BMP7/Bio- Oss复合物;B组仅填入Bio-Oss;C组不充填材料。术后4、8周分期处死动物,取样进行组织学观察和形态学分析。结果A、B组骨缺损处均有新骨形成,A组较B组新骨形成更早、新生骨量更多、骨成熟程度更高（P<0.05）。结论rAAV- BMP7复合Bio- Oss较单纯植入Bio- Oss能更快、更有效地促进种植体周围骨缺损形成新骨,新骨量大且成熟度高,并能形成理想的种植体- 骨结合界面。     

A comparative study of selected properties of ProRoot mineral trioxide aggregate and two Portland cements

AIM: To compare solubility, microhardness and radiopacity of ProRoot mineral trioxide aggregate (MTA) with two Portland cements (PC: CEM I and CEM II). METHODOLOGY: Solubility: for standardized samples (n = 12/group) ring moulds were filled with the cements. These samples were immersed in double-distilled water for 1 min, 10 min, 1 h, 24 h, 72 h, and 28 days. Mean loss of weight was determined. Microhardness: five samples of each cement were produced. All samples were loaded with a diamond indenter point with a weight of 100 g for 30 s. Radiopacity: five samples per cement were produced. These samples were tested according to the ISO standards to compare their radiodensity to that of an aluminium step wedge (1-9 mm). Differences between the three materials with respect to their solubility, microhardness and radiopacity were analysed using ANOVA and Student-Newman-Keuls. RESULTS: After 28 days MTA was of low solubility (0.78%) compared with CEM I (31.38%) and CEM II (33.33%). At exposure times >1 min the two PCs were significantly more soluble than MTA (P < 0.05). The microhardness for MTA was significantly higher (39.99 HV; P < 0.001) compared with the two PC (CEM I: 16.32 HV; CEM II: 13.51 HV). MTA was significantly more radiopaque (5.34 mm Al) than CEM I (3.32 mm Al) and CEM II (2.52 mm Al) (P < 0.05), whereas CEM I was significantly more radiopaque than CEM II (P < 0.05). CONCLUSIONS: Mineral trioxide aggregate displayed superior material properties than both Portland cements.     

The influence of diabetes mellitus and insulin therapy on biomechanical retention around dental implants: a study in rabbits

The oral rehabilitation by dental implants in patients with diabetes remains a controversial issue. The aim of this study was to evaluate the influence of diabetes mellitus and insulin therapy on the bone healing around dental implants using torque removal. Twenty-seven rabbits were randomly divided into 3 groups with 9 animals each: control (C) group, induced diabetic (D) group, and insulin-treated diabetic (ITD) group (10 U/day). After 1 week, one implant was inserted at the tibial metaphysis of the animals. The glucose levels were periodically evaluated through the glucose-oxidase enzymatic method. The animals were killed at 4, 8, and 12 weeks after surgery and the biomechanical test was performed using a torque manometer. Statistically significant differences regarding the removal torque of the implant could not be found at 4 weeks (P = 0.2) among groups. Group C showed statistically higher values than groups D and ITD at the experimental periods of 8 (P = 0.0001 and P = 0.0002, respectively) and 12 weeks (P = 0.0053 and P = 0.001, respectively). There were no statistical differences between D and ITD groups in any of the experimental periods. Diabetes mellitus has negatively influenced the mechanical retention of implants placed at the tibial metaphysis of rabbits. Therapy with insulin did not induce any changes.     

The effect of simvastatin on remodelling of the alveolar bone following tooth extraction

Suppression of residual ridge resorption after tooth extraction is a hot spot in dental research. Recently, simvastatin was reported to influence bone turnover by stimulating bone formation. In this study, the effect of simvastatin application on residual ridge resorption following tooth extraction was investigated. Sixty male Wistar rats were randomly divided into experimental and control groups (n=30). Polylactic acid/polyglycolic acid copolymer carriers, with or without simvastatin, were implanted into extraction sockets of right mandibular incisors. The rats were killed at 1, 2, 4, 8 or 12 weeks after implantation. The relative height of the residual alveolar ridge was significantly greater in the experimental compared to the control group at 2, 4, 8 and 12 weeks. The bone mineral density in the experimental group was significantly higher than that in the control group at 4, 8 and 12 weeks. A larger newly formed bone island was observed in the experimental group at 4 weeks, and higher bone formation rate and quality were found than in the control group at different time points except 1 week. The findings indicate that local application of simvastatin would effectively preserve the residual alveolar bone by promoting bone formation in the extraction socket.     

The effect of high local concentrations of antibiotics on demineralized bone induction in rats.

PURPOSE: This study evaluated the effect of high local concentrations of antibiotics on bone repair induced by demineralized bone in rats. MATERIALS AND METHODS: Seventy-two 3-week-old rats, weighing 200 to 300 g, were used for the experiment. Rats were divided into 4 groups: control group (group 1), saline-impregnation group (group 2), gentamicin-impregnation group (group 3), and tetracycline-impregnation group (group 4). The rats were killed at 3, 8, and 12 weeks after surgery. Samples were stained with hematoxylin-eosin and subjected to the histomorphometric analyses. RESULTS: There were significant differences in new bone formation among groups at all time periods. Comparing differences between groups at each time point, significantly more new bone formation was present in group 2 than in group 1 at 3 weeks, more in group 2 than in group 1 and more in group 2 than in group 4 at 8 weeks, and the most in group 2 among all groups at 12 weeks. In terms of the time period, significantly more new bone formation was observed at 8 weeks during the time period between 3 and 8 weeks, and at 12 weeks during the time period between 3 and 12 weeks. CONCLUSIONS: Our result suggests that the bone graft material is most effective when mixed with saline for the regeneration of osseous defects.     

辛伐他汀复合骨粉在大鼠颞骨表面成骨作用的实验研究

目的 研究辛伐他汀作为激活物对骨生成的促进作用.方法 72只大鼠随机分为3组.实验组大鼠左侧颞骨骨膜下袋内放置辛伐他汀与Bio-Oss骨粉复合物,对照组单纯填入Bio-Oss骨粉.观察大鼠术区情况和生活状态,于术后4、 8、 12周分别处死大鼠,进行组织学观察、新骨总面积测量、成骨细胞计数和红外光谱分析,观察骨增量变化.结果 空白组4、 8、12周颞骨厚度均无明显变化. 4周,骨粉或复合物相对稳定,未见骨痂生长. 8、 12周,实验组与对照组对比明显.新骨面积和成骨细胞数目实验组多于对照组,实验组新骨生长活跃且速度较快;红外光谱分析,骨痂内无机成分高于对照组.结论 辛伐他汀在大鼠颞骨表面植骨过程中,有促进新骨生成作用.     

深冷冻异体骨复合自体髂骨修复免下颌骨缺损的实验研究

目的　研究深冷冻异体骨 (deep frozenallograft,DFA)复合自体髂骨 (autogeneicilium ,AI)移植愈合过程的机理和特点。方法　在 2 0只大白兔的一侧下颌骨缺损内植入深冷冻异体骨复合自体髂骨移植材料 ,另一侧设自体骨对照。植入后 2周、4周、8周、12周 ,行大体标本、X线摄片、X线图象分析骨痂面积与骨痂灰度、组织学及扫描电镜观察骨形成的情况。结果　大体标本 :2周 ,对照组的移植骨愈合优于实验且 ;4、8、12周两组基本相似。X线摄片及组织学 :2周 ,实验组缺损可见自身成骨现象 ;4周形成骨小梁 ;8、12周骨质重建。X线图象分析骨痂面积与骨痂灰度 :实验组与对照组无明显的统计学差异 (P >0 0 5 )。扫描电镜 :实验组与对照组的成骨无差异。结论　深冷冻异体骨复合自体髂骨移植的愈合过程与自体骨相似 ;其成骨表现为骨引导成骨和骨诱导成骨 ,爬行替代是骨块移植愈合的主要方式     

Pulp tissue reaction to a self-adhesive,resin-based direct pulp capping material containing surface pre-reacted glass-ionomer filler

ObjectiveThis study aimed to evaluate the effect of direct pulp capping using an experimental self-adhesive resin for direct pulp capping (SRD) containing silica and surface pre-reacted glass-ionomer (S-PRG) filler on pulpal healing and to monitor the dentin bridge formation in rat pulp 2–4 weeks after operation.MethodsFive types of SRDs (SRD-0: S-PRG fillers 0 wt%; SRD-1: S-PRG fillers 9.1 wt%; SRD-2: S-PRG fillers 18.4 wt%; SRD-3: S-PRG fillers 27.8 wt%; and SRD-6: S-PRG fillers 57.4 wt%) were prepared, and mineral trioxide aggregate (MTA) was used as control (n = 8). Direct pulp capping was performed on rats that were sacrificed for further evaluation 2 or 4 weeks after the operation. The pulp tissue disorganization (PTD), inflammatory cell infiltration (ICI), and reparative dentin formation were histopathologically evaluated; the data were statistically analyzed using the Kruskal–Wallis and the Mann–Whitney U tests.ResultsThe histopathological evaluation of SRD-1-treated test animals 2 weeks post-operation revealed inferior PTD and ICI when compared with that of MTA. Even 4 weeks after the operation in SRD-1- and SRD-2-treated rats, the PTD and ICI were inferior when compared with those of MTA. The dental specimens of SRD-0 and MTA showed orthodentin formation, whereas SRD-treated test animals showed osteodentin formation at a position slightly deeper than the site of the pulpal exposure.SignificanceThe reparative dentin formed by SRD-0 and MTA was genuine, whereas that formed by SRD-3 and SRD-6 was ossified and ectopic. SRD may have the potential to be utilized clinically as a direct pulp capping material.