聚乳酸-羟基乙酸-辛伐他汀对拔牙术后剩余牙槽嵴吸收影响的实验研究

目的探讨聚乳酸-羟基乙酸(PLGA)复合辛伐他汀对剩余牙槽嵴吸收的预防作用。方法选用60只Wistar雄性大鼠,随机分为实验组和对照组各30只,拔除右下中切牙后,实验组即刻植入PLGA-辛伐他汀支架材料,对照组植入PLGA支架材料。术后7、14、28、56、84d分别处死实验组和对照组大鼠各6只,用软X线、骨密度、测量组织学等方法进行药效评价。结果剩余牙槽嵴相对长度:术后14、28、56、84d对照组比实验组[(0·997±0·007)、(0·965±0·139)、(0·996±0·021)、(0·960±0·026)]明显降低,差异有统计学意义(P<0·05)。牙槽骨骨密度:术后28、56、84d实验组[(7·101±0·025)、(7·178±0·039)、(7·162±0·052)g/cm2]与对照组[(7·074±0·014)、(7·117±0·012)、(7·059±0·037)g/cm2]相比明显升高,差异有统计学意义(P<0·05)。组织学观察显示实验组成骨速度和质量优于对照组。结论以PLGA为载体局部应用辛伐他汀可诱导拔牙窝内骨形成,保存了剩余牙槽嵴的长度和骨量。     

复方骨形成蛋白生物复合物预防剩余牙槽嵴吸收实验

目的:观察复方骨形成蛋白牛物复合物植入大鼠下颌切牙拔牙窝用于预防牙槽嵴吸收的效果,为临床应用提供实验依据.方法:选用健康雄性Wistar大鼠54只,随机分为对照组、单纯壳聚糖组、复方骨形成蛋白生物复合物组,18只/组;制备复方骨形成蛋白生物复合物及单纯壳聚糖复合物,分别植入对应组大鼠下颌切牙拔牙窝内;3组动物于3、6、9周每组每次处死6只,切取下颌骨,用软X线机配备Image-Pro Plus软件检查牙槽嵴相对高度,双能X线骨密度分析仪测定骨密度值,常规病理切片观察牙槽窝成骨.结果:3、6、9周复方骨形成蛋白生物复合物组牙槽嵴相对剩余高度和骨密度值均高于对照组及单纯壳聚糖组,差异有统计学意义(P＜0.05);3、6、9周病理切片显示复方骨形成蛋白生物复合物组牙槽窝成骨优于对照组及单纯壳聚糖组.结论:复方骨形成蛋白生物复合物可用来预防拔牙后牙槽嵴的吸收,有广阔的临床应用前景.     

Studies of residual ridge resorption. II. The relationship of dietary calcium and phosphorus to residual ridge resorption

This report presents results of an original investigation of the relationship between dietary calcium and phosphorus and alveolar bone resorption in edentulous patients.The diets of subjects with minimal bone resorption were compared with the diets of subjects with severe alveolar destruction. The results indicate a positive correlation among low calcium intake, calcium/phosphorus imbalance, and severe ridge resorption. Relationships among actual volume intake of these minerals, recommended allowances, and clinical findings were described.Emphasis was placed on the importance of considering dietary factors in the diagnosis and treatment of prosthodontic problems which arise from the excessive resorption of residual ridges.     

Neck design对牙根形种植体边缘骨吸收的影响

目的：评价种植体功能性负载后对种植体表面在边缘骨水平的宏观和微观结构的影响。方法：采用非嵌入式种植一期手术,不行引导骨再生术。种植术后按时间段（3,6,12个月）进行影像学观察。结果：Ankylos种植系统（1.32±0.24mm）3个时段出现轻微的骨吸收,有统计学意义（P〈0.05）。Straumann种植系统（0.76±0.19mm）与Osstem种植系统组（0.21±0.12mm）3个月时段骨吸收量显著减少,但3～6个月与6～12月时段骨吸收量无显著性差异（P〉0.05）。3个种植系统组在上、下颌植入部位的边缘骨吸收量无统计学意义（P〉0.05）。结论：不同颈部设计的牙根形种植体边缘骨吸收量具有显著性差异,宏观表面结构种植体系统比精密颈部与微观表面结构的种植系统边缘骨吸收更稳定。     

局部注射葛根素对鼠拔牙后剩余牙槽嵴吸收影响的实验研究

目的观察中药葛根素对鼠拔牙后剩余牙槽嵴吸收的影响作用。方法制作大鼠下颌中切牙缺失模型,于剩余牙槽嵴的粘膜下注射葛根素,用X线片测量大鼠相对剩余牙槽嵴高度和骨密度值,HE染色观察不同时期剩余牙槽嵴的组织学形态改变。结果实验组剩余牙槽嵴相对高度均大于对照组（P〈0.05）;除一周组外,其余各实验组剩余牙槽嵴光密度测量值均大于对照组（P〈0.01）;组织学观察可见实验组大鼠剩余牙槽嵴表面的成骨质量较对照组高,骨吸收程度较对照组少。结论将葛根素注射于拔牙窝周围能够抑制剩余牙槽嵴的吸收并保存牙槽嵴的高度。     

种植体颈部与唇侧骨板间距离对唇侧牙槽骨吸收及牙龈退缩的影响

目的:探讨前牙美学区植入种植体的颈部与唇侧骨板间距离对种植体周软硬组织的影响.方法:随机选取6只健康Beagle犬,在双侧上颌第一切牙处(共12个位点)行数字化外科导板辅助下的即刻种植和早期种植,并分为4组,A组(早期种植1 mm组),B组(早期种植2 mm组),C组(即刻种植1 mm组),D组(即刻种植2 mm组)....     

Impact of recombinant human bone morphogenetic protein-2 on residual ridge resorption after tooth extraction: an experimental study in the rat.

Residual ridge resorption begins following tooth extraction and continuously reduces alveolar bone volume, potentially creating a significant problem in dental implant treatment. In this study, the role of recombinant human bone morphogenetic protein-2 (rhBMP-2) in residual ridge resorption after tooth extraction was investigated. A polylactic acid/polyglycolic acid copolymer-coated gelatin sponge carrier was implanted with or without rhBMP-2 (1 microg) in the mesial root sockets after removal of maxillary first molars in male Wistar rats. Fine structural and histomorphologic analyses were conducted 3 to 84 days after implantation. Direct bone formation was first observed after 5 days on the rhBMP-2 side, which was transformed into cortical alveolar ridge with a smooth periosteal layer by 84 days, whereas the control side displayed slower healing. Bone histomorphometry revealed greater total bone area and increased bone height after 14, 28, 56, and 84 days on the rhBMP-2 side compared to the control side, and differences were significant after 14, 28, and 56 days. Larger numbers of proliferating cells and densely populated differentiating mesenchymal cells were observed on the rhBMP-2 side than on the control side in the early stage, and chondrogenesis was not observed. The findings indicate that rhBMP-2 may stimulate proliferation and differentiation of mesenchymal cells in the rat maxillary root socket to preserve cortical bone volume in the socket without any evidence of chondrogenesis.     

The value of radiographic predictors of the rate of mandibular residual ridge resorption.

This study tested the relationships between the rate of mandibular residual ridge resorption and the following two variables: cortical thickness at the gonion, and the proportion of cortical bone at the symphysis. These parameters were also compared between men and women. Measurements of cortical thickness at the gonion on panoramic radiographs were compared with similar measurements on lateral cephalometric radiographs. The results showed that neither cortical thickness at the gonion nor the proportion of cortical bone at the symphysis could be used as radiographic predictors of the rate of mandibular bone resorption. The rate of resorption was significantly greater in men than in women, while cortical thickness at the gonion in women was significantly less than that in men. Furthermore, the authors concluded that cephalometric and panoramic measurements should not be used interchangeably.     

The effects of fixed and removable implant-stabilised prostheses on posterior mandibular residual ridge resorption

Abstract: This study investigated the change over time in the area of the posterior mandibular residual ridge in patients wearing either i) mandibular overdentures stabilised by two implants (Brånemark System; Nobel Biocare, Göteborg, Sweden) connected by a bar, or ii) mandibular fixed cantilever prostheses stabilised on five or six implants. Proportional measurements were made in order to compare the area of the residual ridge with an area of bone uninfluenced by resorption. Measurements were made by digitising tracings of panoramic radiographs that were taken shortly after implant insertion and up to seven years later. With the use of overdentures, the posterior bone area index reduced by a mean of 1.1% per annum, while a mean bone area index increase of 1.6% per annum was demonstrated in association with fixed prostheses. A multiple linear regression model was fitted to predict the change in posterior area from type of prosthesis, gender, age, years of edentulism and initial height of the mandible. The model was only significant for initial height of mandible (P = 0.04) and type of prosthesis (P = 0.0001). In conclusion, patients rehabilitated with implant‐stabilised mandibular overdentures demonstrated low rates of posterior mandibular residual ridge resorption, while patients rehabilitated with implant‐stabilised mandibular fixed cantilever prostheses demonstrated bone apposition in the same area.     

Studies of residual ridge resorption. Part I. Use of panoramic radiographs for evaluation and classification of mandibular resorption

This article describes a method of estimating the severity of mandibular bone resorption by using the mental foramen and the inferior border of the mandible, as they appear in panoramic radiographs, as reference points.Measurements of 260 images in panoramic radiographs of normal mandibles reveal that, in a high percentage of films, regardless of the usual magnification or distortion of the images, the lower edge of the mental foramen lies very close to a line dividing the mandible into thirds. By using the approximate ratio of 3:1, the original height of the mandible can be conveniently estimated from the height of the lower edge of the foramen above the inferior border of the mandible. The reduction in height of the bone can then also be estimated.It is suggested that this method of estimating and describing the degree of bone resorption may facilitate the study of this disease by providing an anatomic basis for classifying or grouping patients affected to varying degrees.     

即刻种植和牙槽保存术在维持牙槽嵴骨量中的作用

目的:比较拔牙后即刻种植与拔牙窝内即刻植骨在预防牙槽嵴吸收中的作用.方法:拔除四只犬双侧下颌第二、第三前磨牙,实验组拔牙窝分别植入种植体(A组)和Bio-oss骨粉(B组),对照组(C组)拔牙窝自然愈合.五个月处死动物,观测牙槽嵴的高度和宽度的变化,对骨质进行影像学检查、组织学观察、扫描电镜钙磷能谱分析.结果:牙槽嵴高度减少:A组0.27±0.07mm,B组0.49±O.07 mm,C组1.40±O.15 mm;牙槽嵴宽度减少:A组0.24±0.13mm,B组0.21±O.10 mm,C组1.19±0.51mm,AC和Bc两组间的差异有显著性意义(P<0.05).影像学观察可见种植体与骨组织接触紧密,Bc两组灰度值分别为73.04±7.05、45.10±4.71,两组骨密度差异有显著性意义(P<0.05).组织切片可见A组的种植体周围板层骨包绕紧密;B组的Bio-OSS颗粒部分降解,周围有大量板层骨及编织骨生成;C组骨小梁稀疏、纤细,骨髓腔面积大.扫描电镜钙磷能谱分析测定钙磷比值分别为A组2.01±0.12,B组1.98±0.14,对照组C组1.53±0.22, AC和BC两组间的差异有显著性意义(P<0.05),A、B两组差异无显著性意义(P>0.05).结论:拔牙后即刻种植和拔牙窝内植入Bio-oss联合使用钛膜.均能有效的防止牙槽骨吸收.在拔牙后短期内维持牙槽嵴骨量和骨质的效果上,二者无显著性差别,但均优于自然愈合的拔牙创.讨论:如果拔牙后残存的骨量能保证种植体的初期稳定性,应提倡进行即刻种植,可以有效地防止牙槽骨的萎缩,最大限度的保存种植区软硬组织的形态和功能.牙槽保存术应用于延期种植病人牙槽嵴骨量的维持,但远期的效果还有待进一步观察.     

The effect of variation of residual ridge angle on partial denture abutment tooth movement

Using a laboratory model simulating a free-end saddle partial denture situation, the effect of variation of the angulation of the crest of the residual alveolar ridge to the horizontal on movement of the abutment tooth and saddle was observed. It was found that the inclination of the residual ridge affected the direction and magnitude of abutment tooth movement. The direction of abutment tooth movement was not related to the position of the occlusal rest. However, the magnitude of saddle and abutment tooth movement is affected by the design of the clasp used.     

Marginal bone levels at single tooth implants with a conical fixture design. The influence of surface macro‐ and microstructure

The concept of a conical implant design to accommodate single tooth replacement, has previously been shown to result in excessive bone loss, around the machined titanium conical collar, usually down to the 1st thread. This unusually aggressive loss of bone was shown to occur within a short period of time, post loading, with greater than 3 mm of bone loss occurring within the 1st 6 months to 1 year. The influence of implant design, surface texture and microleakage have all been highlighted as a potential cause. A modification of the surface structure, both at the macroscopic and microscopic level, as well as an altered fixture‐abutment interface design has resulted in the maintenance of marginal bone around a single tooth titanium implant with a similar conical design. The radiographic follow‐up of 33 implants loaded for up to 4 years, has revealed, by comparison, a most favourable maintenance of marginal bone around the conical collar, with a mean marginal bone loss of 0.32 mm mesially and 0.34 mm distally for the whole group. The cumulative mean marginal bone loss mesially and distally is 0.42 mm and 0.40 mm from 1 to 2 years, 0.54 mm and 0.43 mm from 2 to 3 years, 0.51 mm and 0.24 mm from 3 to 4 years, and 0.62 mm and 0.60 mm for implants past their 4 year recall.