Removal torque and histomorphometric investigation of 4 different titanium surfaces: an experimental study in the rabbit tibia

This study presents a histomorphometric and biomechanical comparison of bone response to commercially pure titanium screws with 4 different types of surface topographies placed in the tibial metaphysis of 12 rabbits. Each rabbit had 4 implants placed, 2 in each tibia. The 4 surface topographies were a machined surface, a grit-blasted surface, a plasma-sprayed surface, and an acid-etched (Osseotite) surface. After a healing period of 5 weeks, histomorphometric and removal torque data revealed a significantly higher percentage of bone-to-implant contact and removal torque for acid-etched implants compared to machined, blasted, and plasma-sprayed implants. Within the limits of this short-term experimental study, the results indicated that micro-rough titanium surfaces obtained with acid-etching procedures achieved a 33% greater bone-to-implant contact over machined titanium surfaces with an abutment-type roughness and provided enhanced mechanical interlocking.     

Maintenance of implants: an in vitro study of titanium implant surface modifications subsequent to the application of different prophylaxis procedures

The aim of the present study was to evaluate surface alterations on titanium implant necks subsequent to different prophylaxis procedures. Fifty ITI implants were utilized. Forty implants were treated with 10 different prophylaxis procedures (ultrasonic scaler, plastic tip ultrasonic scaler, stainless steel curette, titanium curette, teflon curette, air powered system, abrasive rubber cups, polishing rubber cup and brush), and 10 implants were left as untreated controls. Surface alterations were studied on an area of 1mm×0.9mm and quantified using optical microscopic, SEM and laser prophylometer analysis. The use of the laser prophylometer provided an objective criterion for evaluation, expressing implant neck surface alterations in numeric values in terms of two roughness indexes, Ra and Rz. The results showed that, in comparison with the controls (Ra=0.50; Rz=3.98) the procedures investigated could be divided into 3 main groups:
1) Methods which altered the implant neck surface producing increased roughness (Ra=0.68–2.08; Rz=4.68–11.92);
2) Methods which left the implant neck surface unaltered (Ra=0.44–0.57: Rz=0.42–3.46);
3) Methods resulting in a smoothening of the implant neck surface (Ra=0.36; Rz=2.15).
Group 1 included procedures that should be avoided. However, it appeared safe to apply the procedures of groups 2 and 3. To confirm these results, it will be necessary to evaluate the plaque‐ and calculus‐removing efficacy from titanium neck implant surfaces in vivo .     

Biomechanical evaluation of a titanium implant surface conditioned by a hydroxide ion solution

Two groups of titanium dental implants, identical in geometry but different in the treatment of their surfaces, were tested in an in vivo minipig model of the mandible. The surfaces that were tested were, first, sandblasted and acid-etched; and secondly, sandblasted, acid-etched, and conditioned. The removal torque was assessed at 2, 4, and 8 weeks after implantation (n=6 animals in each healing period). The interfacial stiffness was also evaluated. All dental implants were well-integrated at the time of death. Removal torque values increased significantly over the course of 8 weeks. Removal torque and interfacial stiffness were increased for conditioned surfaces after 2 weeks, but there were no significant differences between the two surfaces. The sandblasted and acid-etched implants are the standard, and conditioning of the surface showed a tendency to increase early peri-implant formation of bone.     

Bone regeneration using Bioglass: an experimental study in rabbit tibia

Bioglass (BG) has been shown recently to be osteoconductive and osteopromotive in different experimental and clinical conditions. The aim of the present study was to evaluate BG particles in bone defects in rabbit tibia. In control sites, bone was observed only in the peripheral areas of the defects, while in test sites, newly formed bone was found around all BG particles, even those located in the central portion of the defect. Osteoblasts were actively secreting osteoid matrix directly on the granules' surface. BG seems to be a highly osteoconductive material.     

Blood vessels are concentrated within the implant surface concavities: a histologic study in rabbit tibia

Angiogenesis plays a key role in bone formation and maintenance. Bone formation has been reported to initiate in the concavities rather than the convexities in a hydroxyapatite substratum and the implant threads of dental implants. The aim of the present study was to evaluate the number of the blood vessels inside the concavities and around the convexities of the threads of implants in a rabbit tibia model. A total of 32 thread-shaped implants blasted with apatitic calcium phosphate (TCP/HA blend) (Resorbable Blast Texturing, RBT) (Maestro, BioHorizons^®, Birmingham, AL, USA) were inserted in 8 rabbits. Each rabbit received 4 implants, 2 in the right and 2 in left tibia. Implants were retrieved after 1, 2, 4, and 8 weeks and treated to obtain thin ground sections. Statistically significant differences were found in the number of vessels that had formed in the concavities rather than the convexities of the implants after 1 (p = 0.000), and 2 weeks (p = 0.000), whilst no significant differences after 4 (p = 0.546) and 8 weeks (p = 0.275) were detected. The present results supported the hypothesis that blood vessel formation was stimulated by the presence of the concavities, which may provide a suitable environment in which mechanical forces, concentrations and gradients of chemotactic molecules and blood clot retention may all drive vascular and bone cell migration.     

Local effect of titanium implant corrosion: an experimental study in rats

The aim of this study was to evaluate histologically the biological effect of pitting corrosion and to contribute clinically relevant data on the permanence of titanium metal structures used in osteosynthesis in the body. Commercially pure titanium laminar implants (control) and commercially pure titanium laminar implants with pitting corrosion (experimental) were implanted in the tibiae of rats. At 14 days post-implantation the animals were killed. The tibiae were resected, fixed, radiographed and processed for embedding in methyl methacrylate. Percentage of bone-implant contact and peri-implant bone volume were evaluated. The histological study of the titanium implants submitted to pitting corrosion showed scarce bone-implant contact, it was only present in the areas with no pitting and/or surface alterations. There was a statistically significant lower percentage of bone-implant contact in the experimental group (6%+/-4) than in the control group (26%+/-6) (p<0.001). Products of corrosion in the peri-implant bed, especially around the blood vessels and areas of bone marrow in the metal-tissue interface, were observed. The microchemical analysis of corrosion products revealed the presence of titanium. The adverse local effects caused by pitting corrosion suggest that titanium plates and grids should be used with caution as permanent fixation structures.     

The mucosal attachment to titanium implants with different surface characteristics: an experimental study in dogs

BACKGROUND: Findings from in vitro studies have indicated that the orientation and proliferation of cells on titanium surfaces may be influenced by the topography of the surface on which they are grown. It may be argued, therefore, that differences may occur in the mucosal attachment to titanium implants with different surface roughness. AIM: The present experiment was performed to study the composition of the soft tissue barrier that formed to implants prepared with well-defined smooth or rough surfaces. MATERIAL AND METHODS: Five beagle dogs were used. Four implants made of c.p. titanium were placed in the right edentulous mandibular premolar region. After 3 months, two different types of abutments were connected: one experimental (OA) with a dual, thermal acid-etched surface ('Osseotite'), and one regular (RA) abutment with a 'turned' surface. At the end of a 6-month period during which proper plaque control had been maintained, biopsies including the implant and the surrounding soft and hard tissues were obtained, decalcified and processed for light and electron microscopy. A confocal He-Ne laser profilometer was used to study the surface topography of the abutments. RESULTS: The attachment between the peri-implant mucosa and titanium abutments with either a turned (RA; 'smooth') or acid-etched (OA; 'rough') surface was similar from both a quantitative and a qualitative aspect. The attachment comprised a barrier epithelium and a zone of connective tissue attachment of similar dimension at RA and OA. It was further observed that the 'inner' zone of the connective tissue attachment at both types of abutment was composed of about 30-33% fibroblasts and 63-66% collagen. CONCLUSION: It was demonstrated that the soft tissue attachment that formed to implants made of c.p. titanium was not influenced by the roughness of the titanium surface.     

电解蚀刻法处理的钛及钛合金表面的对比研究

目的 通过成骨细胞的体外培养,初步探讨钛及钛合金微-纳米三维形貌对成骨细胞生物学行为的影响。方法采用电解蚀刻法在纯钛及钛合金表面构建出不同尺寸的微-纳米三维形貌,并观察其三维结构表面对成骨细胞黏附、增殖、细胞形态、碱性磷酸酶（ALP）活性的影响。结果在成骨细胞的黏附和增殖方面,纯钛组和钛合金组表面均高于纯钛机械抛光组。纯钛组表面细胞胞体饱满,伸出大量伪足,并可见大量功能颗粒。ALP活性显著高于钛合金和纯钛机械抛光组表面。结论通过电解蚀刻法在纯钛和钛合金表面可形成不同直径和深度的碗形巢样及纳米结构;两个表面即30~50 μm和5~8 μm的表面和光滑表面相比,都明显促进了细胞的附着;30~50 μm的纯钛表面更有利于促进细胞的增殖和分化。     

等离子渗氮表面处理对纯钛材料细菌黏附能力的影响

目的：研究等离子渗氮对钛表面的组织结构、性能及对变形链球菌黏附的影响。方法：将相同规格的钛片60片经逐级抛光后随机分成抛光组和等离子渗氮表面处理组。测量所有试件表面的粗糙度值,并采用扫描电镜、Axiovert 25CA光学图像分析仪及GDA750对钛表面渗镀层的表面形貌情况进行分析;将材料接种于变形链球菌悬液1h,在荧光显微镜下计数黏附细菌的数量。结果：等离子渗氮表面处理仅使纯钛表面粗糙度略微增加,并均在0.2μm以下;扫描电镜显示,等离子渗氮表面处理后材料表面的原始划痕消失;GDS检测分析结果表明,等离子渗氮表面处理后,表面主要由氮化钛化合物组成。经渗氮处理后,纯钛黏附细菌的量显著减少。结论：纯钛经等离子渗氮表面处理后形成了稳定的改性层,且能减少细菌的黏附。     

Radiographic evaluation of dental implants with different surface treatments: an experimental study in dogs

PURPOSE: The aim of the study was to radiographically measure the bone density at the peri-implant region after osseointegration and to compare the relative bone density achieved by different surface-treated implants. MATERIALS AND METHODS: Four different types of implant surfaces were compared, using five young-adult male mongrel dogs. The first, second, third, and fourth lower premolars were extracted. Ninety days after removal, four 3.75-mm diameter and 10-mm long screw implants (Paragon) were placed with different surface treatments in the lower hemiarches. The dogs received two implants each of the following surface treatments: 1) smooth (machined); 2) titanium plasma spray: 3) hydroxyapatite coating; and 4) sandblasting with soluble particles. The implants were maintained unloaded for 90 days. After this period, the animals were killed and the hemimandibles were extracted and radiographed. The grey level of the bone adjacent to implants was measured with a specific software tool (line histogram) and the relative bone density was calculated. RESULTS: The four different surface treatments promote different numeric levels of bone density around the dental implants (sandblasting with soluble particles, 52.45 +/- 2.95; titanium plasma spray, 53.98 +/- 3.67; machined, 55.78 +/- 3.06, and hydroxyapatite coating, 58.2 +/- 2.71). Therefore, the implants can be ranked in terms of relative bone density from high to low as follows: sandblasting with soluble particles, titanium plasma spray, machined, and hydroxyapatite coating. There were no statistically significant differences in bone density among the four groups (P = 0.1130, analysis of variance). CONCLUSION: Surface treatments that add roughness to the implant show numerically higher bone density when compared with machined surfaces. The findings of radiographic density analysis suggest that the soluble blasting media-treated surface provides a greater bone density at the peri-implant region.     

Biomechanical evaluation of malleable noncompression miniplates in mandibular angle fractures: an experimental study

The purpose of this experimental study was to test the reliability of a single malleable titanium miniplate using Champy's method of fixing fractures of the mandibular angle. Eighteen sheep hemimandibles were used to evaluate 2 plating techniques. The groups were tested with either a single non-compression titanium miniplate or a single malleable titanium miniplate. A cantilever bending biomechanical test model was used for the samples. Each group was tested with vertical forces using a servohydraulic testing unit. The displacement values in each group at each 10N stage up to 90N were compared using 2-way analysis of variance (ANOVA). The displacement values for the 2 groups differed significantly (p<0.01). The variance analyses showed that the biomechanical behaviour of a single non-compression miniplate was better than that of a single malleable miniplate. The non-compression miniplate fixed by screws had greater resistance to occlusal loads than the malleable plate fixed by screws, and the malleable plate alone was not sufficient to withstand the early postoperative bite force.