Evaluation of bone turnover after bisphosphonate withdrawal and its influence on implant osseointegration: an in vivo study in rats

Clinical Oral Investigations - The aim of this study was to investigate bone turnover alterations after alendronate (ALD) withdrawal and its influence on dental implants osseointegration. Seventy...     

The influence of thread geometry on implant osseointegration under immediate loading: a literature review

Implant success is achieved by the synergistic combination of numerous biomechanical factors. This report examines the mechanical aspect of implants. In particular, it is focused on macrodesign such as thread shape, pitch, width and depth, and crestal module of implants. This study reviews the literature regarding the effect of implant thread geometry on primary stability and osseointegration under immediate loading. The search strategy included both in vitro and in vivo studies published in the MEDLINE database from January 2000 to June 2014. Various geometrical parameters are analyzed to evaluate their significance for optimal stress distribution, implant surface area, and bone remodeling responses during the process of osseointegration.     

螺纹形态和螺距对种植体系统应力影响的三维有限元研究

目的研究根据标准螺纹参数设计的不同螺纹形态和螺距的9种牙种植体受载后牙槽骨及整个种植系统的应力变化,为种植体系统的优化设计及临床应用提供理论依据。方法采用Solidworks软件建立了螺纹形态分别为V形、梯形、锯齿形,螺距分别为0.7 mm、0.8 mm、1.0 mm的9种标准螺纹式种植体模型,配以基台、基台螺丝构成整套种植体系统,根据CT扫描数据重建下颌骨模型,在垂直向和与种植体长轴成15°斜向分别加载100 N力,ANSYS有限元分析软件计算比较种植体系统和周围牙槽骨的应力及位移分布状况。结果综合考虑种植体系统各部件和种植体周围牙槽骨所受应力,9种种植体中,螺纹形态为V形、螺距为0.8 mm的种植体在垂直向和斜向加载时应力较小。9种种植体各部件及周围牙槽骨最大位移量垂直向加载时为2.61μm,斜向加载时为23.78μm,9种种植体的位移差异小。结论螺纹形态为V形、螺距为0.8 mm的种植体力学性能较好。螺纹形态和螺距对种植体系统及周围牙槽骨的位移影响不大。     

3D打印多孔钽种植体对骨整合影响的实验研究

目的 研究多孔钽及多孔钛种植体对骨整合的影响。方法 通过计算机辅助设计方法建模,采用3D打印技术制备两种微孔参数相同的多孔材料种植体：多孔钽及多孔钛。在24只新西兰大白兔双侧股骨外踝处建立骨缺损模型,每只动物左右侧缺损随机分组,分别用多孔钽（实验组）和多孔钛（对照组）种植体进行修复。种植体植入后2、4、8周取材,进行大体观察和亚甲基蓝-酸性品红染色,观测种植体和骨界面的骨整合情况,采用推出实验测试种植体-骨界面结合强度。 结果 术后2、4、8周,两组材料界面的新生骨组织逐渐增加,出现新生骨小梁并向材料孔隙内生长;两组的成骨情况及种植体-骨组织界面结合强度的差异无统计学意义（P>0.05）。结论 3D打印的多孔钽能与骨组织形成早期的生物结合,具有与多孔钛相当的骨整合能力。     

高海拔低氧环境对种植体骨结合的影响

目的:比较不同海拔高度对牙种植体周围成骨及种植体固位的影响。方法:选择广州、西宁、果洛3地区作为不同海拔地区分组,将微型种植体植入3地区饲养的兔胫骨中,通过X线观察、生物力学测试及硬组织切片法分析3地区种植体骨结合的差异。结果:X线显示,种植体植入4周时,广州组种植体周围X线骨密度最高,果洛组最低;生物力学最大拔出力(N)在4周时3组分别为194.5±4.5、176.3±6.7、165.6±2.71,12周时分别为206.7±6.5、180.5±4.8和168.3±5.2,广州组明显高于后2组(P<0.05);组织学染色分析显示,4周时3组骨接触率(%)分别为48.85±3.3、40.76±2.4和36.87±4.13(P<0.05);12周时3组骨接触率分别为50.34±5.1、41.62±2.8和39.78±3.7,广州组明显高于后2组(P<0.05)。结论:高海拔低氧环境影响种植体的骨结合。     

Variables that influence the relationship between osseointegration and bone adjacent to an implant

It is often assumed that there is a direct relationship between the bone density adjacent to an implant, as revealed by radiographs, and the percent histologic osseointegration. Moreover, the lack of standardized methods for evaluation of histologic preparations makes it difficult to compare published studies, especially as little is known about the variables that influence these measurements. In this animal study, computer-assisted lineal analysis was used to evaluate the effects of subject, tooth position, and implant surface site on measured bone density and osseointegration in a bone augmentation experiment. Three sites--coronal lingual, apical lingual, and apical facial--were analyzed around each of 6 (3.75 x 8 mm) threaded machined titanium implants, as well as the apical facial site of 21 other implants placed in the mandibular premolar area of 5 dogs. In all sites, a progressive decrease in bone density was observed from bone adjacent to the implant to that at the titanium implant surface. There was an animal effect on osseointegration, but there were no differences between the mandibular premolar locations (second, third, and fourth). Most importantly, there were significant measurable effects attributable to the surface site examined. The need for carefully standardized histologic evaluations is established.     

Bone conditioning to enhance implant osseointegration: an experimental study in pigs

PURPOSE: Osseointegration of implants depends on time and the local bone conditions regarding quality and quantity. This led to the bone classification by Lekholm and Zarb. The aim of the present study was to enhance osseointegration of implants through conditioning of the bone bed and to compare in this context the efficacy of bone condensation, an osteoinductive collagen (Colloss), and platelet-rich plasma (PRP). MATERIALS AND METHODS: Porcine frontal skull bone was used for the preparation of Identical-size implant beds. Before placement of the implants (Ankylos, 3.5 x 4 mm), the implant beds were untreated (control) or conditioned with condensation, Colloss, or PRP. The animals were sacrificed after 2, 4, and 8 weeks. The specimens were then compared and analyzed by microradiography, and statistical analysis was performed using the Wilcoxon signed rank test. RESULTS: At the early observation times, significant effects on the sites of topical bone conditioning in comparison to the control group could be seen regarding the implant-bone interface (2 weeks: control 31%, Colloss 60%, condensation 73%, PRP 47%; 4 weeks: control 39%, Colloss 51%, condensation 40%, PRP 42%) and peri-implant bone density (2 weeks: control 31%, Colloss 48%, condensation 59%, PRP 39%; 4 weeks: control 47%, Colloss 53%, condensation 41%, PRP 50%). A leveling of the results between groups was found at 8 weeks (implant-bone interface: control 51%, Colloss 58%, condensation 55%, PRP 62%; peri-implant bone density: control 50%, Colloss 55%, condensation 51%, PRP 51%). DISCUSSION: Overall, bone condensation and Colloss apparently influenced bone formation process from the onset, but over the entire 8-week healing period, differences in bone formation were not significant CONCLUSION: It can be stated that, in the initial healing phase, an effect of topical bone conditioning may be achieved by the different described methods.     

Hydroxyapatite-electroplated cp-titanium implant and its bone integration potentiality: an in vivo study

PURPOSE: This study was designed to precipitate hydroxyapatite coating on the surface of commercially pure titanium (cpTi) implants using an electroplating technique. After characterization of the hydroxyapatite coating, the bone-implant interface and bone integration of both cpTi and hydroxyapatite-coated implants were assessed. MATERIALS: Twenty implants were divided equally into 2 main groups (n = 10). Ten cpTi implants were utilized as received, while the others were hydroxyapatite coated and then sterilized. The implants of both groups were inserted in the tibiae of New Zealand rabbits. The purity and crystallinity of the hydroxyapatite coat were characterized using x-ray diffraction. A scanning electron microscope examined the grain morphology. Profilometer evaluated the surface texture before and after sterilization. Histological examination using a scanning electron microscope was performed to qualify osseointegration of the regenerated bone and measure the gap distance at the bone-implant interface. RESULTS: Pure crystalline hydroxyapatite precipitate of thickness (range 69-78 microm) and rough surface (2.7 +/- 0.2 microm) compared to smooth cpTi (1.3 +/- 0.5 microm). The gamma-radiation sterilization resulted in finer grains and insignificant smoother surface. Histological examination of the cpTi implant exhibited less bone regeneration with few and less dense bone trabeculae, and gap distance was significantly high (1.29 +/- 0.51 microm). Meanwhile, the hydroxyapatite-coated implant showed a recognizable amount of bone regeneration with more and denser bone trabeculae, and gap distance ranged from 0 to 1.32 microm. CONCLUSIONS: The employed technique provided a thin and uniform pure crystalline hydroxyapatite coating. The characterization of the precipitated film is promising for clinically successful long-term bone fixation.     

A comparison of biocompatibility and osseointegration of ceramic and titanium implants: an in vivo and in vitro study

This study compared the biocompatibility in vitro and the osseointegration in vivo of zirconium and titanium implants regarding implant surfaces and the bone-implant contacts. The different implant surfaces and the biocompatibility of zirconium versus titanium implants were determined by vitality and cytotoxic tests in vitro. The contact of the osteoblasts to the implant surface was determined by scanning electron microscopy (SEM). The in vivo study for osseointegration was performed in domestic pigs over 4 and 12 weeks. In each animal, 4 zirconium and 4 titanium implants (WhiteSky, BlueSky, Bredent, Germany) were inserted in the os frontale and analysed by histomorphometry. Cytotoxicity and SEM showed good biocompatibility in relation to the investigated implant materials. Histological results showed direct bone-implant contact of the implant surfaces. The zirconium implants showed a slight delay in osseointegration in terms of bone-implant contact as measured by histomorphometry (after 4 weeks, zirconium (59.3 ± 4.6%) versus titanium (64.1 ± 3.9%); after 12 weeks, zirconium (67.1 ± 2.3%) versus titanium (73.6 ± 3.2%). A statistically significant difference between the two groups was not observed. The results indicated similar biocompatibility and osseointegration for zirconium compared to titanium implants.     

Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs

Aim: To study osseointegration and bone‐level changes at implants installed using either a standard or a reduced diameter bur for implant bed preparation. Material and methods: In six Labrador dogs, the first and second premolars were extracted bilaterally. Subsequently, mesial roots of the first molars were endodontically treated and distal roots, including the corresponding part of the crown, were extracted. After 3 months of healing, flaps were elevated and recipient sites were prepared in all experimental sites. The control site was prepared using a standard procedure, while the test site was prepared using a drill with a 0.2 mm reduced diameter than the standard one used in the contra‐lateral side. After 4 months of healing, the animals were euthanized and biopsies were obtained for histological processing and evaluation. Results: With the exception of one implant that was lost, all implants were integrated in mineralized bone. The alveolar crest underwent resorption at control as well as at test sites (buccal aspect ～1 mm). The most coronal contact of bone‐to‐implant was located between 1.2 and 1.6 mm at the test and between 1.3 and 1.7 mm at the control sites. Bone‐to‐implant contact percentage was between 49% and 67%. No statistically significant differences were found for any of the outcome variables. Conclusions: After 4 months of healing, lateral pressure to the implant bed as reflected by higher insertion torques (36 vs. 15 N cm in the premolar and 19 vs. 7 N cm in the molar regions) did not affect the bone‐to‐implant contact. To cite this article:
Pantani F, Botticelli D, Garcia IR Jr., Salata LA, Borges GJ, Lang NP. Influence of lateral pressure to the implant bed on osseointegration: an experimental study in dogs.
Clin. Oral Impl. Res. 21 , 2010; 1264–1270.
doi: 10.1111/j.1600‐0501.2009.01941.x     

不同种植扭力对一段式种植体骨结合影响的动物实验研究

实验目的:本研究的目的是通过动物实验观察用不同扭矩植入的一段式种植体与骨结合的情况.实验方法:选取4只成年雄性杂种狗,体重10-15Kg,分别拔除每只狗的双侧第一第二前磨牙,待3个月后分别以20Ncm、30Ncm、40Ncm的力矩旋入BLB种植体各一枚,即刻安装上部基台结构并调整咬合,每只狗在植入种植体术后一个月和三个月时拍片观察其影像学改变,于种植术后一个月和三个月时分别处死两只狗取标本,观察其组织学的改变.实验结果:12枚种植体中以30Ncm、40Ncm植入的8枚种植体获得了良好的骨结合,种植体周围包饶着致密的骨组织,未观察到任何间隙和结缔组织长入,另外以20Ncm植入的4枚种植体中3枚脱落,1枚松动.实验结论:在30Ncm及40Ncm扭转力矩下旋入的一段式种植体可获得良好的骨结合.     

A comparison of elastomeric auxiliaries versus elastic thread on premolar extraction site closure: an in vivo study

Twenty-five patients requiring symmetric premolar extractions (representing eighty quadrants requiring canine retraction) were entered into the study. Standard 0.022 X 0.028-inch Siamese edgewise appliances with 0.016 X 0.022-inch arch wires were used during canine retraction. In 30 of the quadrants, canine retraction was accomplished with Unitek Alastik chain; 10 quadrants were treated with Rocky Mountain energy chain (medium). In the remaining 40 groups, canine retraction was accomplished via Unitek nylon-covered latex thread. The forces initially applied to the system were between 350-400 grams. Patients were seen at 3-week intervals to measure the amount of space closure and to change the elastic modules. A comparison among the three groups revealed no significant differences in rates of canine retraction (P less than 0.05). Empirically, the elastomeric auxiliaries were found to be more hygienic and required less chair time to apply than did the elastic thread.     

Effects of implant thread geometry on percentage of osseointegration and resistance to reverse torque in the tibia of rabbits

BACKGROUND: Dental implant thread geometry has been proposed as a potential factor affecting implant stability and the percentage of osseointegration. Therefore, the aim of this prospective, randomized, parallel arm study was to evaluate the effects of dental implant thread design on the quality and percent of osseointegration and resistance to reverse torque in the tibia of rabbits. METHODS: Seventy-two custom-made, screw-shaped, commercially pure titanium implants (3.25 mm diameter x 7 mm length) were placed in the tibiae of 12 white New Zealand rabbits. Each tibia received three implants of varying thread shapes: one with a V-shaped, one with a reverse buttress, and one with a square thread design. The rabbits were sacrificed following an uneventful healing period of 12 weeks. Implants in the right tibiae underwent histologic and histomorphometric assessments of the bone-to-implant contact (BIC) and the radiographic density of surrounding bone, while implants in the left tibiae were used for reverse-torque testing. Differences between the three thread designs were examined using analysis of variance (ANOVA). RESULTS: Data showed that the square thread design implants had significantly more BIC and greater reverse-torque measurements compared to the V-shaped and reverse buttress thread designs, while no differences were found in radiographic bone density assessments. CONCLUSION: These results indicate that the square thread design may be more effective for use in endosseous dental implant systems.     

Lateral ridge augmentation and implant placement: an experimental study evaluating implant osseointegration in different augmentation materials in the canine mandible.

The present study investigated the osseointegration of dental implants with a titanium plasma-sprayed surface (TPS) in regenerated and native bone in an experimental dog study. Initially, lateral bone defects were created in the alveolar ridge on both sides of the mandible. Two months later, lateral ridge augmentation was performed with (1) autogenous corticocancellous block grafts, (2) autogenous corticocancellous block grafts and e-PTFE membrane, (3) tricalcium phosphate particles and e-PTFE membrane, or (4) canine-derived demineralized freeze-dried bone allograft particles and e-PTFE membrane. After 4 months, membranes were removed, and non-submerged titanium implants were placed in regenerated bone (test implants) and in native bone (control implants). Two months later, the animals were sacrificed and non-decalcified orofacial sections were evaluated histometrically. All implants demonstrated high percentages (59% to 75%) of bone-to-implant contact, with no significant differences across the various treatment groups. The different grafting techniques did not significantly influence the location of first bone-to-implant contact and the horizontal bone width at the most coronal bone level.     

补肾中药合剂促进牙种植体骨结合体内试验

目的：用组织病理学、影像学方法评估补肾中药合剂对牙种植骨结合的效果。方法：12只兔子随机分成二组,均在其胫骨顶端植入纯钛种植体,一组饲料中加入补肾中药合剂,另一组饲料中没加入任何药物,30天、60天后处死免子,分别用组织病理学及影像学方法评估种植体骨结合的情况。结果：试验组的病理学及影像学结果明显优于对照组;结论：补肾中药合剂能促进种植体骨结合。     

Influence of the implant abutment on the Periotest value: an in vivo study.

OBJECTIVE: Periotest values for dental implants depend on the type of prosthetic abutment utilized for the restoration. If Periotest value cannot be measured at the single crown, the Periotest values used for comparison must be derived from the same type of superstructure. METHOD AND MATERIALS: Fifty-nine patients were selected from a regular follow-up program. At the end of the healing period, the Periotest values of Frialit-2 implants were measured at the gingiva former and abutment. The values were then compared with the Periotest measurements obtained at the placement of the final single crown and during the first follow-up examination. RESULTS: Compared to values measured at single crowns, the Periotest value measured at gingiva formers decreased on average by 3.5. The measurement of the abutment revealed a decrease of 1.7. Until the first recall and under functional loading of implants, the Periotest value increased on average by 1.8. These differences significantly differed from 0. CONCLUSION: If measurements at different abutments such as crown abutments or single crowns are necessary, comparison of the Periotest values in accordance with the given mean values will lead to more precise results. It is recommended that Periotest measurements be performed for the first and subsequent prostheses, during all prosthetic stages, to allow comparison if some parts of the prosthetic abutment have to be replaced.