Drilling dimension effects in early stages of osseointegration and implant stability in a canine model

Background

This study histologically evaluated two implant designs: a classic thread design versus another specifically designed for healing chamber formation placed with two drilling protocols.

Material and Methods

Forty dental implants (4.1 mm diameter) with two different macrogeometries were inserted in the tibia of 10 Beagle dogs, and maximum insertion torque was recorded. Drilling techniques were: until 3.75 mm (regular-group); and until 4.0 mm diameter (overdrilling-group) for both implant designs. At 2 and 4 weeks, samples were retrieved and processed for histomorphometric analysis. For torque and BIC (bone-to-implant contact) and BAFO (bone area fraction occupied), a general-linear model was employed including instrumentation technique and time in vivo as independent.

Results

The insertion torque recorded for each implant design and drilling group significantly decreased as a function of increasing drilling diameter for both implant designs (p<0.001). No significant differences were detected between implant designs for each drilling technique (p>0.18). A significant increase in BIC was observed from 2 to 4 weeks for both implants placed with the overdrilling technique (p<0.03) only, but not for those placed in the 3.75 mm drilling sites (p>0.32).

Conclusions

Despite the differences between implant designs and drilling technique an intramembranous-like healing mode with newly formed woven bone prevailed. Key words: Histomorphometry, biomechanical, in vivo, initial stability, insertion torque, osseointegration.     

种植体掺离子表面改性技术及其促进骨结合的研究进展

种植牙因其在解决牙列缺损方面巨大的优势,已成为许多缺牙患者首选的治疗方式。在临床应用中,如何促进种植体与骨组织界面的骨结合是种植治疗成功的关键,因此种植体表面改性一直是研究的热点。骨组织中含有钙、磷、锌、镁、锶等大量微量元素,这些微量元素对于骨组织的生长发育必不可少。因此可以通过将微量元素掺入种植体表面来促进种植体骨结合。本文着重介绍了种植体表面改性的相关技术以及微量元素促进骨结合的具体机制。     

Enhancement of osseointegration by generating a dynamic implant surface

Preparations of autologous plasma rich in growth factors (PRGF) are used to promote healing and tissue regeneration. We seek to determine whether covering the titanium implant surface with this preparation could enhance osseointegration. The interaction of PRGF with the surface of titanium implants was examined by environmental scanning electron microscopy (ESEM). A total of 23 implants were placed in the tibiae and radii of 3 goats; 13 implants were inserted after covering the surface and filling the alveolus with PRGF, and 10 more implants were inserted following a conventional protocol and served as controls. Histomorphometric analysis of the bone-implant interface was performed after 8 weeks. Finally, 1391 implants were placed in 295 patients after bioactivating the surface with PRGF. Stability and implant survival were evaluated. The implant surface adsorbed the protein-rich material as shown by ESEM. In the animal study, osseointegration was enhanced when the surface was covered with PRGF as shown by histomorphometry (bone-implant contact: 51.28% +/- 4.7% vs 21.89% +/- 7.36%; P < .01). Finally, studies in patients showed that 99.6% of the implants treated with PRGF were well osseointegrated. Clinical use of this technique in oral implantology can improve the prognosis.     

种植体表面处理技术对骨结合影响研究进展

种植修复在临床的推广应用，引发了种植骨结合领域的研究热潮。种植体表面经过处理，可改变其表面性能，从而促进骨结合的形成，提高种植的成功率。本文对近年来应用于临床的多种种植体表面处理技术做一综述。     

Influence of implant geometry and surface characteristics on progressive osseointegration

PURPOSE: Although no currently available technique for the measurement of osseointegration is entirely satisfactory, 3 clinical variables can be reasonably associated with the process: probing depth, micromobility, and crestal bone height. Micromobility can be quantified to some extent with the use of the Periotest, a commercially available instrument In this investigation, the influence of surface characteristics and geometry upon Periotest value (PTV) and probing depth measurements was studied. MATERIALS AND METHODS: In a multicenter trial, 120 healthy edentulous patients received 5 or 6 implants in the anterior mandible and were followed for 3 years. A total of 634 implants were placed. Every patient received at least 1 implant of each of 3 types: threaded titanium plasma-sprayed (TPS), threaded hydroxyapatite-coated (HA), and cylindric HA-coated. A randomization schedule assured that approximately equal numbers of each type of implant were placed and that they were uniformly distributed over the arch. RESULTS: Of the 4 tested combinations of dependent and independent variables, the only statistically significant (P < .05) effect was that of coating on PTV. At 1 year after prosthetic restoration, the mean PTV for HA-coated threaded implants was -5.36 +/- 1.24, compared with -4.86 +/- 1.70 for TPS implants. This difference steadily declined in magnitude and significance, until, after 3 years, the groups were indistinguishable. DISCUSSION: This study agrees with the previous observations that HA coating tends to accelerate the initial rate of osseointegration. The absence of a difference between threaded and cylindric implants confirms that the PTV responds to micromobility near the surface, on a scale much smaller than such gross geometric features. CONCLUSION: On the basis of these results, one may conclude that HA-coated implants exhibit a more rapid decrease in micromobility than do TPS implants of identical geometry.     

巨噬细胞在种植体骨结合及早期失败的研究进展

随着现代化医疗技术的完善和发展,种植牙成功率已经越来越高.然而,种植失败仍有发生,早期失败则在其中占了很大的比重.异物反应是宿主识别外来植入物发生的免疫反应,然而过度异物反应引起的纤维包封以及种植体表面的腐蚀则会阻碍骨结合,导致种植体早期失败.作为参与异物反应的主要免疫细胞,巨噬细胞可以在不同的刺激下被诱导分化成M1型...     

Negative effects of alcohol intake and estrogen deficiency combination on osseointegration in a rat model

Alcohol intake and estrogen deficiency can both affect bone physiology and have shown to have an adverse effect on dental implant therapy. However, the combination of both factors on osseointegration is unknown. The aim of this study was to evaluate osseointegration in rats fed with alcohol and presenting induced estrogen deficiency. Ninety-six female rats were divided according to diet and hormonal condition into 6 groups as follows: group Sh-W: sham (simulated ovariectomy) control, food and water ad libitum; group Sh-Et: sham, food and 20% ethanol solution ad libitum; group Sh-Su: sham, food and sucrose solution controlled to ensure an isocaloric diet in relation to Sh-Et; group Ov-W: ovariectomy, food and water ad libitum; group Ov-Et: ovariectomy, food and 20% ethanol solution ad libitum; and group Ov-Su: ovariectomy, food and sucrose solution controlled to ensure an isocaloric diet as Ov-Et. The groups were subdivided according to time of euthanasia: 30 and 45 days after placement of implants. Implant surgery was performed 1 month after ovariectomy or sham. After euthanasia, the femurs were removed and evaluated by histomorphometry. Groups Ov-Et and Ov-Su showed the lowest percentage of bone-to-implant contact. The combination of alcohol intake and estrogen deficiency, and the combination of estrogen deficiency and reduced ingestion of food can negatively affect osseointegration in rats.     

SLA种植体表面干扰LRP5信号影响骨结合的实验研究

目的通过构建干扰型LRP5慢病毒(LV-LRP5),评估LRP5基因的干扰对大颗粒喷砂酸蚀表面处理(SLA)的种植体表面骨结合的影响。方法种植体表面进行SLA处理,构建LV-LRP5慢病毒载体,通过转染骨髓基质干细胞(BMSCs)检测转染效果。SLA表面处理种植体分为两组:LV-LRP5组和空白组。LV-LRP5的种植体周围注射shRNA病毒液,空白组常规种植。6周后取含有种植体的组织块进行硬组织切片,HE染色观察和评估新骨的形成,测量种植体-骨接触率和种植体螺纹内的骨密度来评价成骨的效果。结果 LV-LRP5能稳定转染BMSCs。种植体植入6周后,空白组种植体与新骨之间的接触较广泛,而LV-LRP5组种植体与新骨之间的接触较局限。LV-LRP5组的种植体-骨接触率及螺纹内骨密度均较空白组低,经统计学分析,两组在6周时具有显著性差异(P<0.05)。结论 SLA种植体表面干扰LRP5降低了种植体骨结合,该过程可能通过降低Wnt/LRP5信号系统或联结其他成骨信号系统进行。     

不同植入扭矩对种植体骨结合影响的临床初步探究

目的利用共振频率分析法观察不同的种植体植入扭矩值对不同时间点种植体稳定性以及骨结合效果的影响。方法根据纳入及排除标准选择牙列缺损成年患者49名,共植入86颗种植体,手术由同一高年资种植科医生操作完成。根据种植体植入就位后的所测最终扭矩值(Itv)进行分组:A低扭矩组,Itv为0~15 N·cm;B中扭矩组,Itv为16~35 N·cm;C高扭矩组,Itv为36~50 N·cm。利用共振频率分析仪分别对种植即刻、术后8周、术后12周的稳定指数(ISQ)进行测量分析,比较组内以及不同组间不同时间点种植体稳定性以及骨结合效果的差异。结果 1各扭矩组内比较,随着时间的延长,所有组ISQ均呈上升趋势,其中低、中扭矩组内各时间点间均有统计学差异,高扭矩组内各时间点间均无统计学差异。2各扭矩组间第8周ISQ值无明显差异,低扭矩组第8周ISQ值增加幅度最大;各扭矩组间第12周ISQ值无明显差异。结论种植体植入8周以内是形成良好的种植体骨结合的关键时期;不同的种植体植入扭矩值对于8周以后的骨结合效果影响差异不显著。     

钛种植体表面早期成骨方式的动物模型研究

目的：研究适合用于观察钛种植体表面早期成骨方式的动物模型。方法对原有的种植体植入模式进行改进,使种植体植入动物体内的初始状态为种植体外螺纹贴于种植窝骨壁,种植体螺纹内部与周围骨壁保持一定距离。4只Beagle犬下颌骨延期植入20枚种植体,植入后2周和4周分别处死2只Beagle犬,对标本进行组织学观察。结果4只Beagle犬手术创口均达到一期愈合,未出现种植体松动。组织学观察可见种植体表面新骨生成,种植体周围骨壁新骨生成,可清楚地观察到新骨生成方向,可观察到接触成骨和距离成骨。结论本研究创建的动物模型可以清晰地观察钛种植体表面早期成骨的方式,也可客观地反映种植体表面性能对其表面早期成骨方式的影响。     

Effect of ovariectomy and alendronate on implant osseointegration in rat maxillary bone

Bisphosphonates such as alendronate (ALD), although controversial, are worthy of investigation for the enhancement of implant osseointegration in patients with low bone mass who are already taking bisphosphonates for osteoporosis. These patients may receive additional benefits and be acceptable candidates for dental implants without needing to change their medication regimen and possibly as a result of their medication regimen. The purpose of this study was to compare implant osseointegration in maxillary bone of normal rats with a rat model of postmenopausal estrogen deficiency (ovariectomized [OVX]), with and without ALD. An experimental group of 32 rats was divided in 4 groups: ALD-OVX (n=8 OVX with ALD), OVX (n=8 OVX without ALD), ALD (n=8 normal rats with ALD), and control (n=8 normal rats). All rats received one titanium microscrew implant in the left edentulous region of the maxillary arch. The ALD-OVX and ALD groups received subcutaneous injections of ALD 3 times a week. On the fourth week after ALD administration, an implant was placed in all 32 rats. The maxilla of each rat was radiographed 4 times: at 0, 7, 14, and 28 days. On day 28 after implant placement, all rats were killed, and the peri-implant tissue was embedded in plastic or paraffin for histological examination. The X rays were used for a chronologic calculation of the contact ratio between implant and bone surfaces. Radiographic bone density was determined at 3 points: mesial, apical, and distal. The results show that osseointegration of the implants was impaired in the estrogen-deficient OVX rats compared with the ALD-OVX rats. Fifty percent of the implants were lost at 2 weeks in the OVX group. Radiographic evidence suggested that none of the implants in the OVX group osseointegrated. In the histologic examination more bone was observed around implants from the ALD-OVX and ALD groups than around implants from the OVX group. The OVX group presented a dramatic reduction in implant bone contact at 2 weeks and a significant 13% reduction at 4 weeks vs day of implant (P = .006). The ALD-OVX group presented 50% more bone density than the OVX group (P = .0003). Both ALD groups (ALD and ALD-OVX) had significantly higher radiographic bone density than the other groups (P < .01 for each comparison). In conclusion, osseointegration of implants was enhanced by ALD. Radiographic bone density and contact ratio improved with ALD administration. Implant osseointegration was impaired by estrogen deficiency in the OVX group.     

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.     

系统性药物对种植体骨结合影响的动物实验研究进展

种植体周围骨结合是口腔种植重要的生物学基础。影响种植体骨结合的因素繁多,包括手术因素、种植体因素、患者自身因素等,其中应用系统性药物以改善种植体骨结合的相关研究已经成为当今的研究热点。本文基于动物实验研究,对系统性药物影响种植体骨结合的作用进行综述,以期为改善种植体骨结合提供可供选择的高效安全的系统性药物,为后期临床试验的开展奠定基础。     

Effects of implant geometry and surface treatment on osseointegration after functional loading: a dog study

summary  The purpose of this study was to evaluate the geometry and surface characteristics of osseointegration after functional loading by radiographic, periodontal and histomorphometric analyses. We analysed three groups of implants with different geometry and surface characteristics using experimental dogs. The control group received Brånemark implants (group 1). Group 2 and group 3 implants each had a 0·5-mm pitch height but differed in surface characteristics. Group 2 implants were machine surfaced and group 3 implants were thermally oxidized at 800 °C for 2 h in a pure oxygen atmosphere. For these experiments, which used a total of four healthy beagle dogs, the implants were randomly installed into the extracted first, second and third premolar positions. The animals received radiographic and clinical periodontal examinations at 6 and 12 months post-loading, and were then killed for histomorphometric analysis. The radiographic analysis showed that mean crestal bone resorption in the control group was greater than that observed in the experimental groups ( P  < 0·05). The percentage of bone-to-implant contact for group 3 (83·7%) was significantly higher than in groups 1 (74·4%) and 2 (75·0%) ( P  < 0·05). Overall, implant geometry and surface treatment affected the rate of crestal bone resorption and bone healing surrounding the dental implants.     

The effects of implant surface roughness and surgical technique on implant fixation in an in vitro model

OBJECTIVES: The aim of the present study was to determine the relationship between implant surface parameters, surgical approach and initial implant fixation. MATERIAL AND METHODS: Sixty tapered, conical, screw-shaped implants with machined or etched surface topography were implanted into the explanted femoral condyle of goats. The implant sites were prepared either by a conventional technique, by undersized preparation, or by the osteotome technique. Peak insertion & removal torque, bone-to-implant contacts (BIC) and morphological bone appearance were assessed by scanning electron microscope (SEM) and micro-computer tomography. (micro-CT). RESULTS: Insertion and removal torque values were significantly higher for etched implants inserted with the undersized technique (115.2 +/- 31.1, 102.9 +/- 36.4 N cm) respectively. Also, the average BIC value was higher for the etched implants placed with the undersized technique (87.5 +/- 5.6), which was statistically significant compared with machined and etched implants inserted by conventional technique. CONCLUSION: In conclusion, this study shows that the surgical technique has a decisive effect on implant fixation (represented in this study by installation torque value/removal torque value and histomorphometric evaluation) in trabecular bone. Nevertheless, additional in vivo studies have to be done to prove the importance of surgical protocol for the final implant-bone response.