种植体-基台连接形式对种植体周围骨组织应力分布的影响

目的分析种植体-基台连接形式对种植体周围骨组织应力分布的影响，从生物力学角度探讨平台转换连接形式防止或减少种植体周围骨吸收的可能机制。方法利用COSMOSM2．85软件包建立种植体支持的下颌第一磨牙三维有限元模型，种植体-基台的连接形式分别采用平齐对接（模型A）和平台转换（模型B）。采用垂直和斜向两种形式加载，载荷均为200N，比较两种模型种植体周围骨组织的应力分布情况以及种植体-骨界面颊舌侧相同位置的von Mises应力大小。结果不同加载条件下两种模型种植体周围骨组织应力集中在种植体颈部颊舌侧骨皮质内，斜向加载时最大von Mises应力值高于垂直加载时。模型A和模型B骨组织内最大von Mises应力值在垂直加载时，分别为11．61MPa和7．15MPa，斜向加载时分别为22．07MPa和11．87MPa。距离种植体-基台连接处越远，von Mises应力值越小，骨皮质到骨松质交界处的应力变化最明显。与模型A相比，模型B种植体-骨界面相同节点的最大von Mises应力值较小。结论与平齐对接形式相比，平台转换设计可改善种植体周围骨组织的应力分布，降低种植体颈部骨组织所受的应力。     

骨吸收对平台转换种植体周围骨组织内部应力的影响

目的:观察骨吸收对平台转换设计种植体周围骨组织内部应力的影响。方法:利用COSMOS 2.85软件包建立不同程度骨吸收的种植体支持下颌第一磨牙金属冠三维有限元模型共10个。种植体-基台的连接形式分别采用平齐对接(模型A)和平台转换(模型B)设计,模型又分为无骨吸收(A0,B0)和骨吸收的深度分别为0.5mm(A1,B1)、1.0mm(A2,B2)、1.5mm(A3,B3)和2.0mm(A4,B4)5种。采用垂直和斜向两种形式加载,载荷均为200N。观察骨吸收程度对种植体周围骨组织内部应力的影响,并比较不同程度骨吸收时两种设计种植体周围骨组织内部应力的不同。结果:平台转换种植体和平齐对接种植体周围骨组织内部的应力分布相似,应力主要集中在种植体颈部。随着骨吸收程度的增加,应力集中的范围增大;当皮质骨完全吸收后,种植体根部也出现应力集中的趋势。种植体周围骨组织内部的最大等效应力随着骨吸收程度的增加而减小,当皮质骨完全吸收后改变最明显。同等程度骨吸收时,平台转换设计种植体周围骨组织内部的最大等效应力小于平齐对接设计;随着骨吸收程度的增加,两者的差距逐渐减小。结论:骨吸收会导致种植体周围骨组织内部应力集中的范围加大而最大等效应力减小;骨吸收后平台转换设计改善种植体周围骨组织应力分布的作用变得不明显。     

对种植体周围炎的认识与预防

种植体周围炎是种植治疗常见并发症之一。种植体周围炎是导致种植治疗失败的重要原因,其具有患病率高,治疗难度大等特点。如何正确的认识种植体周围炎并预防其发生是每一位口腔种植医生都需面对的重要问题。     

糖尿病对种植体骨结合影响的研究进展

糖尿病患者种植牙的研究，是种植牙研究中的一个热点。本文就糖尿病患者种植牙临床应用情况，糖尿病对种植体骨结合影响的研究进展和提高种植体成功率的方法，作一综述。     

利用基因芯片分析糖尿病大鼠种植体周围骨组织的差异表达基因

目的:应用基因表达谱芯片对糖尿病与正常大鼠种植体周围骨组织的基因表达谱进行对比分析,并筛选差异基因.方法:将6只Wistar大鼠随机分为糖尿病组和正常组,糖尿病组采用链脲佐菌素(Streptozotocin,STZ)腹腔注射法建立糖尿病大鼠模型.分别在大鼠右侧胫骨骨骺端植入钛种植体,3个月后,截取种植体周围骨组织,提取总RNA,进行包括17983个基因的全基因组表达谱芯片检测,对差异表达基因进行GO分析,并采用实时定量PCR对芯片结果进行验证.结果:芯片结果显示,差异基因共1084个,其中糖尿病组表达增强352个,表达降低732个,GO分析涉及1154个不同的功能分类.结论:糖尿病大鼠种植体周围骨组织中与成骨相关的基因表达降低,与脂类代谢相关的基因表达升高.     

胰岛素对糖尿病大鼠种植体周骨组织代谢影响的研究

目的 探索胰岛素治疗对于高糖环境下种植体周骨组织代谢及种植体-骨结合的影响.方法 构建糖尿病大鼠模型,在大鼠股骨植入钛种植体,并给予胰岛素治疗;同时通过成骨细胞培养,体外构建高糖环境,给予胰岛素干预.结果 糖尿病大鼠种植体周骨组织形成和矿化明显降低,胰岛素干预治疗能起到明显的改善作用;此外,胰岛素干预后成骨细胞中胰岛素受体表达明显增加.结论 胰岛素也许通过胰岛素信号通路调控高糖环境中成骨细胞功能,改善骨组织的形成和矿化.     

冷冻异体骨膜引导即刻种植体周围骨缺损修复的临床研究

目的：观察机体对冷冻异体骨膜的反应及其引导骨组织再生的效果，方法：在实验研究成功的基础上，将冷冻异体骨膜作为引导组织再生膜性材料应用于引导即刻种植义齿植体周围骨缺损的修复。结果：临床观察证实机体对冷冻异体骨膜无排斥反应，膜无脱出，无感染，骨缺损修复率达到92．12％，结论：冷冻异体骨膜是一种理想的引导组织再生膜性材料。     

修复材料对种植体周围骨组织应力的影响

目的：研究不同上部结构材料对种植体固定修复中种植体周骨组织的应力反应特点。方法：建立种植体支持固定桥力学模型，通过三维有限元方法分别计算出采用丙烯酸树脂，釉质瓷，瓷，金合金为上部结构材料时骨组织的应力状况，结果：每况工况下，种植体颈部周围皮质骨区所受的应力都是最大的，四种材料比较时使用丙烯酸树脂对种植体颈部骨组织的应力最小，其次为釉质瓷，瓷，最大为金合金，结论：修复材料的弹性模量会影响种植体周骨组织的应力分布，弹性模量低者对种植体颈部周围骨组织有保护作用，釉质瓷可能是较为理想的修复材料。     

种植体周围软组织水平的影响因素

随着种植义齿在口腔临床上的广泛运用,人们对种植修复的效果要求越来越高,不再只局限于成功率和恢复咀嚼功能,而是希望能够得到更加自然美观的修复效果,从而种植美学成为当今种植领域的研究热点。     

软组织瓣早期裂开或穿孔对种植体颈缘部骨组织的影响

放射线性片评估种植手术后软件组织瓣早开裂或穿孔对种植体周边缘骨吸收的影响。方法：１７例种植患者,植入的３２颗两段式骨内种植体,其中１７颗出现软组织瓣早期裂开或穿孔,导致种植体早期暴露。根据种植体入当天及种植Ⅱ期手术（安装愈合基台）前的Ｘ线片（根尖片）,测量出种植体颈部边缘骨高度的变化。结果：早期暴露的种植体均产生明显吸收,近中平均１．９５ｍｍ,远中平均２．１５ｍｍ;而正常愈合种植体（非裂开）骨变化     

Influence of cortical bone quality on stress distribution in bone around dental implant

Using finite element method (FEM), this study sought to investigate how the thickness and Young's modulus of cortical bone influenced stress distribution in bone surrounding a dental implant. The finite element implant-bone model consisted of a titanium abutment, a titanium fixture, a gold alloy retaining screw, cancellous bone, and cortical bone. The results showed that von Mises equivalent stress was at its maximum in the cortical bone surrounding dental implant. Upon investigation, it was found that maximum von Mises equivalent stress in bone decreased as cortical bone thickness increased. On the other hand, maximum von Mises equivalent stress in bone increased as Young's modulus of cortical bone increased. In conclusion, it was confirmed that von Mises equivalent stress was sensitive to the thickness and Young's modulus of cortical bone.     

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。     

Effect of bone to implant contact percentage on bone remodelling surrounding a dental implant

Dental implants are an effective, safe and predictable solution for patients suffering from tooth loss, but implant placement changes the normal mechanical environment of the jawbone leading to bone density redistribution and ‘remodelling’, in order to adapt to the new environment. Many bone remodelling theories assume the presence of 100% contact between bone and implant, which is inconsistent with clinical reality. About 50–80% bone–implant contact is commonly seen with clinically successful implants. The influence of different percentages of bone–implant contact on bone remodelling has not been investigated adequately. This study aims to evaluate this influence using a newly proposed remodelling algorithm through a 2D finite element model. Four different degrees of bone–implant contact (25, 50, 75 and 100%) are considered and their influences on the density distribution of the jawbone are evaluated. The predicted results indicate that no matter what the initial percentage of bone–implant contact (25–100%), the final outcome is about 58–60% contact when an equilibrium state is reached by bone remodelling. The results are consistent with clinical observations and findings.     

种植体穿通下颌骨对骨界面应力分布的影响

目的：为了探讨下颌种植牙穿通下颌骨后对骨界面应力分布的影响。方法：采用三维有限元方法,通过单个穿下颌螺旋型种植体的种植,了解穿下颌种植后对骨界面应力分布的影响。结果：穿下颌种植减小了颈周密质骨内的应力,加大了根端侧穿下颌骨下缘处的应力,减小了骨界面的位移。结论：穿下颌种植,改变了骨界面的最大应力分布部位,使最大应力位于根端侧下颌骨下缘处。     

Effect of alendronate on bone remodeling around implant in the rat

PURPOSE

The purpose of this study was to evaluate the effect of alendronates on bone remodeling around titanium implant in the maxilla of rats.

MATERIALS AND METHODS

The maxillary first molars were extracted and customized-titanium implants were placed immediately in thirty male Sprague-Dawley rats. The rats were divided into experimental (bisphosphonate) group and control group. At 4 weeks after implantation, the rats in the bisphosphonate group were subcutaneously injected with alendronate three times a week for 6 weeks where as the rats in control group were injected with saline. The rats were sacrificed at 1, 2, 3, 4, or 6 weeks after starting of injection and maxillary bones were collected subsequently. Alveolar bone remodeling around the implants were evaluated by radiographic and histologic analysis. Microarray analysis and immunohistomorphologic analysis were also performed on one rat, sacrificed at 6 weeks after starting of injection, from each group. Statistical analysis was performed using repeated measures analysis of variance and independent t test at a significance level of 5%.

RESULTS

There was no statistically significant difference in the bone area (%) around implant between the bisphosphonate group and the control group. However, the amount of empty lacuna was significantly increased in the bisphosphonate group, especially in the rats sacrificed at 4 weeks after starting of injection compared to that of the corresponding control group. The bisphosphonate group showed the same level of TRAP positive cell count, osteocalcin and angiopoietin 1 as the control group.

CONCLUSION

Alendronate may not decrease the amount of osteoclast. However, the significantly increased amount of empty lacuna in the bisphosphonate group may explain the suppression of bone remodeling in the bisphosphonate group.     

Effect of diabetes mellitus and insulin therapy on bone density around osseointegrated dental implants: a digital subtraction radiography study in rats

Objectives: To evaluate the effect of diabetes mellitus (DM) and insulin therapy on bone density around osseointegrated dental implants by digital subtraction radiography (DSR).
Material and methods: Forty implants were placed in tibiae of 40 adult rats. After a healing period of 2 months, the animals were divided into four groups of 10 animals each: a 2-month control group, sacrificed at time (A), a diabetic group (D), an insulin-treated group (I) and a 4-month control group (C). During 2 months, group I received subcutaneous doses of insulin, whereas groups C and D received only saline. The animals in groups D, I and C were thereafter sacrificed. The glucose plasma levels (GPLs) were monitored throughout the experiment. Film radiographs were taken at implant surgery and on the day of sacrifice. The radiographs were digitized, and bone density in regions of osseointegration (OR) around the implants was evaluated by quantitative DSR between baseline and final images. Differences in shades of gray among the groups were assessed using ANOVA.
Results: GPLs were within normal range for groups A, C and I and higher for group D. There was a significant difference in mean gray shade values in the OR of subtraction images between groups D (122±7) and I (136±5) ( P <0.05) while there were no significant differences between control groups A (128±13) and C (134±10) and the insulin group I.
Conclusions: DM impaired bone density around osseointegrated dental implant. Further, insulin therapy maintained bone density in diabetic rats.     

Experimental study of bone growth around a dental implant after Surgibone grafting

Histologic and histomorphometric results of bone growth around titanium alloy screw-type implants after Surgibone grafting in New Zealand white rabbits are presented. At 21 days, new bone was formed along the surface of the implant. At 84 days, newly formed bone replaced almost all of the trabecular bone of the graft and reached the shoulder level of the implant. There was a higher percentage of host bone area at 84 days than at any of the earlier experimental periods (P < .01). The average mineral apposition rates ranged from 1.82 to 2.35 microns/day in original bone and 2.55 to 2.80 microns/day in newly formed bone. The results suggest that Surgibone grafting in combination with dental implants can be used to increase the height of the recipient bone and therefore aid in the fixation of the implant in this animal model.     

牙种植体即刻种植骨愈合过程的组织学观察

目的：了解即刻种植体的骨愈合过程，验证即刻种植的可行性。方法：在１２只犬下颌前磨牙新鲜拔牙创内立即植入纯钛牙种植体，通过组织学光镜和扫描电镜观察术后２、４、６、８、１２周种植体周围骨缺损修复过程和种植体骨结合形成情况。结果：骨缺损区内血块首先机化，而后沿牙槽窝骨壁向中心方向逐渐骨化形成新骨。小于１ｍｍ骨缺损１２周内可完全修复，种植体骨结合形成；１ｍｍ以上骨缺损则不能完全修复。结论：即刻种植体周围骨缺损的修复和骨结合形成类似于拔牙创的愈合，大于１ｍｍ的骨缺损应争取植骨。