Investigation for bone fixation effect of thin HA coated layer on Ti implants

In 1995, the author reported the development of unique cementless total hip joints applying hydroxyapatite (HA) flame coating onto a porous titanium surface which is arc-sprayed with pure titanium material in argon gas at atmospheric pressure. The surface roughness of the porous layer was 360 microm Rmax, and the layer was more resistant to blast erosion than the conventional low pressure plasma sprayed porous layers. The thickness of the HA layer was between 20 and 40 microns considering the balance of bone conduction effect of HA and the risk of mechanical detachment of the layers from the porous titanium. Short-term animal tests showed excellent results. At that time a specific question was raised as to whether or not the coated HA layers would remain in the living bone for a long time. The results obtained from observation of retrieved specimens show that the thickness of the HA coating layer is sufficient for new bone formation after implantation, and HA would be absorbed in the body within a few years, after contributing to the new bone formation.     

Fate of the HA coating of loaded implants in the augmented sinus floor: a human case study of retrieved implants

A histomorphometric study was performed on six retrieved loaded hydroxyapatite (HA)-coated titanium implants. The implants had been clinically functioning in a 50-year-old patient. She originally presented a severely atrophic maxilla that was reconstructed by sinus floor augmentation using autogenous bone from the iliac crest. In spite of good clinical function, because of psychiatric problems, all implants, including some bordering bone, were removed using a trephine bur. Thin ground sections were prepared for histology and used for histomorphometry. The aim of this study was to observe the condition of the calcium phosphate coating after 2.5 years of functional loading, the nature of the bone-to-implant interface, as well as the density of the bone graft around the implants. Intimate and abundant bone-to-implant contact was observed, ranging from 90.4% to 99.8% along the implant surface. Active bone remodeling occurred within all threads, as demonstrated by secondary osteons close to the implant surface. The thickness of the calcium phosphate coating varied from 51 to 88 pm for the loaded retrieved implants, versus 53 to 89 microm for the nonused control implant. All implants showed bone contact including the first thread and up to the smooth titanium neck. Both the nature and thickness of the coating had hardly changed after 2.5 years of loading. The HA-coated implants used achieved excellent osseointegration and must be considered clinically safe and effective in maxillary grafted bone.     

Characterization, at the bone crystal level, of the titanium-coating/bone interfacial zone

Well integrated and clinically functional titanium dental implants retrieved in humans after 14 and 40 months of settlement were used for the characterization of the interfacial area between the plasma-sprayed coating and the surrounding mineralized bone. Electron microscopic studies were performed from undecalcified intact coating/bone interfaces. The concomitant presence of direct bone tissue apposition on the titanium coating, as well as the interposition of amorphous material along the same interfacial zones emphasizes the dynamic biologic aspect of the osseointegration process. A very striking finding of these ultrastructural and microanalytical investigations was the presence of tiny titanium grains ranging from 5 to 50 nm in diameter at the surface of bulky plasma-sprayed coating particles. High-resolution transmission electron microscopy revealed a continuity between the lattice planes of the coating material and those of the minute titanium grains; thus indicating a chemical binding. The thickness of the granular titanium layer interposed between coating particles and mineralized bone tissue ranged up to 600 nm. The observation of calcium-phosphate needle-like crystallites within the porous layer made of titanium grains indicates a bone ingrowth process, suggesting a bone-binding mechanism to the outer surface of the coated titanium implant.     

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.     

Titanium casting into phosphate bonded investment with zirconite.

OBJECTIVE: Reaction layer structure of the titanium castings surface was investigated when a new centrifuge-vacuum-pressure cast titanium machine and a zirconite inner investment was used. METHODS: The micro-hardness of titanium castings was measured using a Knoop's hardness tester. The structure of reaction layers and the distribution of elements on the surfaces of titanium castings were analysed by SEM and EDS, respectively, when zirconite was used as the inner investment for cast titanium. RESULTS: Knoop's micro-hardness at distances of 50 and 75 microm from the titanium casting surfaces made directly in phosphate investment molds had significantly harder surfaces than those made in zirconite coating molds. The thickness of the reaction layer on the surface of titanium castings was <35 microm with zirconite coating and was >50 microm without zirconite coating. The structure of reaction layer was divided into four layers from the outer surface to the inner including: sintering layer, alpha-Case, Si-rich layer, acicular crystal structure. The distribution of elements was different on each layer. SIGNIFICANCE: The thickness of the cast titanium reaction layer was reduced when the wax patterns were coated with zirconite. The surface of the titanium castings was smooth and without cracks, and the investment on the surface of titanium castings was easily removed.     

选择性激光烧结多孔钛种植体及其性能研究

目的 分析选择性激光烧结（SLS）多孔钛种植体的机械性能及生物相容性,探讨其与壳聚糖（CS）/羟磷灰石（HA）复合涂层结合后的促骨结合作用。方法 制备Ti6Al4V试件,部分试件表面进行CS/HA涂层处理;对试件进行扫描电子显微镜观察和机械性能检测;体外培养MC3T3-E1细胞,进行活/死细胞染色、甲基噻唑基四唑（MTT）及碱性磷酸酶（ALP）水平检测;将柱状螺纹种植体植入兔股骨髁部,分析其体内生物学性能。结果 试件准弹性梯度随孔隙率增大而减小,孔隙率为30%时与皮质骨接近,70%时与松质骨接近;试件具有良好的生物相容性。复合CS/HA涂层后可促进MC3T3-E1细胞增殖、分化,有利于骨组织长入孔隙,形成良好的骨结合。结论 多孔钛种植体具有良好的机械性能和生物相容性,与CS/HA涂层结合后具有骨诱导性,利于形成稳定的骨结合。     

Torsional stability of HA-coated and grit-blasted titanium dental implants.

Hydroxylapatite (HA)-coated and grit-blasted (non-HA-coated) titanium dental implants were inserted into healed extraction sites of canine mandibles. After six weeks, the animals were killed and the implants mechanically tested in torsion to failure. Interface attachment strength, implant/tissue compatibility, integrity of the HA coating, and the location of interface failure were evaluated. Mechanical testing demonstrated an interface torsional strength of 3.98 +/- 0.93 MPa for the HA-coated implants and 2.25 +/- 0.65 MPa for the grit-blasted implants. This represents a 76.9% improvement in the maximum torsional interface strength, and is statistically-significant (p = 0.0004). On qualitative histologic analysis, interface failure was seen to occur primarily at the HA/implant interface, although failure through the HA coating and regions of bone/HA interface failure were observed. The HA-coated implants had bone in direct apposition to their surface with no fibrous tissue interposition. The grit-blasted implants also had regions of direct bone-implant apposition, but these areas were limited to a smaller proportion of the total interface area. There was no evidence of breakdown or change in thickness of the HA coating.     

Human histologic and histomorphometric analyses of hydroxyapatite-coated implants after 10 years of function: a case report

PURPOSE: No consensus exists on the long-term performance of hydroxyapatite (HA) coatings on dental implants. The aim of this study was to evaluate the long-term stability of the HA coating in a human autopsy specimen. MATERIALS AND METHODS: Two mandibular HA-coated implants were retrieved postmortem from a woman after 10 years of functional loading with an implant/tooth-supported fixed partial denture. After ground sectioning, the specimens were histomorphometrically analyzed. RESULTS: Direct bone-implant contact was found at 78.48% of the implant surface. HA coating disappearance had occurred in a few areas (22.75%), but bone was in direct apposition to the titanium surface. Bone volume measured 27.66%, and expected bone-implant contact was 37.55%. No inflammatory reaction was seen in the supracrestal soft tissues or the bone compartment. DISCUSSION: Most of the HA coating was maintained on the implants, and areas lacking HA were directly apposed by bone. This observation suggests that the underlying titanium surface should have a macro-texture to promote the adaptation of bone to the titanium surface in case of HA disappearance, as well as to decrease failure at the HA-titanium interface. CONCLUSIONS: In a patient in whom prosthetic treatment was appropriately performed and proper plaque control was maintained, the HA coating was not damaged and contributed to the success of the implant over 10 years of clinical functioning.     

Histologic evaluation of threaded HA-coated root-form implants after 3.5 to 11 years of function: a report of three cases

This article presents a histologic evaluation of three hydroxyapatite (HA)-coated root-form implants retrieved from humans after being in function for 3.5 to 11 years. If the coronal portion, where bone loss was observed clinically and radiographically, is excluded, all implants appeared to be well osseointegrated, with intimate contact between the surrounding bone and the coating. There was no sign of resorption or dissolution of the HA coating. The coating had a uniform thickness (50 microm) equal to the thickness originally provided by the manufacturer In the few areas where there was no bone contact, the HA coating appeared to line the implant with no sign of dissolution. The few detached particles had tight contact with the bone, demonstrating the biocompatibility of the HA. The observations from the three reported cases suggest that the HA coating of dental implants may not be susceptible to resorption or dissolution under long-term function.     

Surface characteristics of electrochemically oxidized implants and acid-etched implants: surface chemistry, morphology, pore configurations, oxide thickness, crystal structure, and roughness

PURPOSE: This study was undertaken to investigate surface properties of surface-modified titanium implants in terms of surface chemistry, morphology, pore characteristics, oxide thickness, crystal structure, and roughness. MATERIALS AND METHODS: An oxidized, custom-made Mg implant, an oxidized commercially available implant (TiUnite), and a dual acid-etched surface (Osseotite) were investigated. Surface characteristics were evaluated with various surface analytic techniques. RESULTS: Surface chemistry showed similar fingerprints of titanium oxide and carbon contaminant in common for all implants but also revealed essential differences of the elements such as about 9 at% Mg for the Mg implant, about 11 at% P for the TiUnite implant and about 12 at% Na for the Osseotite implant. Surface morphology of the Mg and TiUnite implants demonstrated a duplex oxide structure, ie, an inner barrier layer without pores and an outer porous layer with numerous pores, whereas the Osseotite implant revealed a crystallographically etched appearance with pits. The diameter and depth of pores/pits was < or = 2 microm and < or = 1.5 microm in the Mg implant, < or = 4 microm and < or = 10 microm in the TiUnite implant, and < or = 2 microm and < or = 1 microm in the Osseotite implant, respectively. Oxide layer revealed homogeneous thickness, about 3.4 microm of all threads in the Mg implants. On the contrary, TiUnite showed heterogeneous oxide thickness, about 1 to 11 microm, which gradually increased with thread numbers. Crystal structure showed a mixture of anatase and rutile phase for the Mg implants. With respect to roughness, Sa showed 0.69 microm in the Mg implant, 1.35 microm in the TiUnite implant, and 0.72 microm in the Osseotite implant. CONCLUSIONS: Well-defined surface characterization may provide a scientific basis for a better understanding of the effects of the implant surface on the biological response. The surface-engineered implants resulted in various surface characteristics, as a result of different manufacturing techniques.     

A clinical retrospective evaluation of FA/HA coated (Biocomp®) dental implants. Results after 1 year.

In this retrospective clinical evaluation, the performance of loaded titanium implants with a bilayer bioactive surface coating of the relatively reactive hydroxylapatite (HA. outer layer) and the more stable fluorapatite (FA, inner layer) was evaluated. 98 consecutive patients were included in the study for a total of 354 implants, loaded by overdentures, fixed partial dentures and single tooth replacements. Statistical analyses revealed a cumulative probability of implant survival on a per patient basis of 94.5%(s.e. 2.7%) one year after implant installation. On implants that were lost parts of the bilayer FA/HA coating had vanished as a result of primary or secondary infection and subsequently epithelial down growth. Most complications were associated with implants placed in the maxilla. Periotest values (PTV) were generally high, indicating adequate osseointegration. The PTV's were statistical significantly less favorable in implants placed in the maxilla. The most favorable PTV's and gingival index scores were found around implants servicing overdentures. Marginal bone loss averaged ‐ 2mm during the observation period. The amount of marginal bone loss corresponded with the distance from the neck of the implant to the first thread of the implant's cervical screw‐section. It is concluded that, during the relatively short observation period, the FA/HA coated implants function adequately. However, in the absence of a direct implant‐to‐bone contact preceding implant loss, part of the FA/HA coating on the titanium implants generally dissolves.     

Bone healing capacity of titanium plasma‐sprayed and hydroxylapatite‐coated oral implants

The influence of surface quality, in particular surface topography and implant material, was evaluated by inserting titanium‐ and hydroxylapatite plasma‐sprayed coated implants into the maxilla of 10 goats. Three types of plasma‐spray coatings were applied to tapered, screw shaped implants; titanium plasma‐spray coating (TPS), titanium plasma‐spray coating with additional acid passivation (TPSA) and a bilayered coating (TPS/HA) consisting of titanium plasma‐spray coating (TPS) and a hydroxylapatite part (HA). In addition, as machined implants (TIM) were used as control. A total of 40 implants were inserted according a balanced split plot design. At the end of a 3‐month healing period, it appeared that 5 implants (2 TPS, 1 TPSA, 1 TPS/HA and 1 TiM) were lost. Histological examination revealed a stronger bone response to TPS/HA coated implants. Even the TPS/HA coated implants induced bone formation on the part of the implant inserted into the sinus. No signs of delamination of the TPS coatings were visible. The HA part of the dual coating showed signs of degradation. Histomorphometrical analysis confirmed these findings. A significant difference in bone contact ( P <0.05) was measured between the TPS/HA coated implants and the other types of implants. Linear regression ( r >0.2) showed no correlation between the inscrew values at the base line and the bone contact measurements 3 months after healing. On the basis of these results, we can conclude that the chemical composition of the HA coating has a positive influence on the bone reaction. The influence of roughness is less evident.     

Bone replacement with porous hydroxyapatite blocks and titanium screw implants: an experimental study.

The aim of this experimental study was to examine whether porous hydroxyapatite (HA) blocks, fixed with titanium screw implants, could be used as a bone graft substitute. Twenty minipigs received coralline HA blocks for augmentation of surgically created defects in edentulous mandibles. Each block was fixed with two titanium screw implants. Two types of porous HA blocks that differed in pore diameter were used. A high rate of HA loss occurred in the group of animals that had received the HA block with small pore sizes, and fractures of the block occurred in the vicinity of the titanium implants in 12 of the remaining 13 cases. Histologic examination showed that the HA blocks with larger pore size were homogenously penetrated by bone that extended into the central pores and even incorporated the dislocated block fragments. The titanium implants were in close contact with the newly formed bone in these blocks. Little contact between bone and implants was seen in the HA blocks with the smaller pore size. The results indicate that, with improved mechanical properties, a combined augmentation with porous HA blocks and screw implants may be useful in primary reconstruction of bone defects.     

Surface properties and biocompatibility of nitrided titanium for abrasion resistant implant materials

Corrosion, other related properties and biocompatibility of surface nitrided titanium were investigated to examine its possible use as an abrasion resistant implant material. The nitrided layer about 2 microm thick composed of TiN and Ti2N was formed on titanium by a gas nitriding method. The dissolved amount of titanium ion in SBF was as low as the detection limit of ICP, and that in the 1% lactic acid showed no significant difference from titanium. The tissue reaction of the cylindrical implant in soft tissue of rats showed no inflammation, and fine particles of 1 microm induced phagocytosis, which was similar to titanium. The implantation in the femor showed the new bone formed in direct contact with implants. All the results suggested that the wettability, corrosion resistance, S. mutans adhesion and biocompatibility were nearly equivalent to those of titanium. The surface of nitrided titanium was promising, with biocompatibility comparable with titanium, as an implant material such as for an abutment part of a dental implant, which requires high abrasion resistance.     

A new porous hydroxyapatite for promotion of bone regeneration in maxillary sinus augmentation: clinical and histologic study in humans

PURPOSE: This study was undertaken to evaluate clinically, histologically, and immunohistochemically the use of a new porous hydroxyapatite (HA) (B. Agra, Cabon, Milan, Italy) as a grafting material for maxillary sinus augmentation with simultaneous implant placement. MATERIALS AND METHODS: A total of 28 titanium implants were placed in 12 patients with an average of 4.5 mm of bone on the sinus floor. HA granules were packed around the implants in the sinus cavity. After a healing period of 5 to 6 months, second-stage surgery was carried out. In 5 patients, bone cores were harvested from grafted areas and processed for histology and immunocytochemistry. RESULTS: All implants were clinically stable at second-stage surgery and were followed for an average of 3 years. The histology showed newly formed bone in direct contact with the HA granules. Immunohistochemistry showed the presence of large quantities of bone sialoprotein and osteopontin in and around the granules of HA. DISCUSSION AND CONCLUSION: This study suggests that a new porous HA accommodated sinus floor augmentation in patients with 3 to 5 mm of bone height preoperatively. By possibly attracting circulating biocomponents at sites of tissue repair, it may promote bone regeneration.     

Effect of calcium phosphate surface coating on bone ingrowth onto porous-surfaced titanium alloy implants in rabbit tibiae.

PURPOSE: The purpose of the present study was to determine whether calcium phosphate coating has a significant impact on bone ingrowth into a porous titanium implant. MATERIALS AND METHODS: Porous-surfaced titanium alloy Ti-6Al-4V implants were prepared with or without the addition of a thin surface layer of calcium phosphate applied by sol-gel coating. Implants were placed into the tibiae of 16 rabbits. Implanted sites were allowed to heal for 2 weeks, after which specimens were retrieved for morphometric assessment using backscatter scanning electron microscopy. RESULTS: The data collected show that there is more extensive ingrowth into the porous regions of the calcium phosphate-coated implants than into the control implants. The weighted average ingrowth for the calcium phosphate-coated implants was 2.01, whereas that for the noncoated implants was 1.49; the difference is statistically significant (P <.01). CONCLUSIONS: The addition of a thin layer of calcium phosphate to these implants appears to promote a more extensive implant-to-bone interface by allowing the neck regions to become intimately ingrown with bone even after only 2 weeks of initial healing.     

Observations of the bone activity adjacent to unloaded dental implants coated with Polyactive® or HA

Summary In addition to bone-bonding bioma-terials such as calcium phosphate ceramics and Bioglass/glass ceramics, an elastomeric poly(ethylene oxide) poly(butylene terephthalate) (PEO/PBT) segmented block co-polymer (Polyactive®) was recently introduced. In contrast to ceramic bioma-terials, Polyactive® is a flexible material. In a previous three-dimensional finite element analysis study, it was stated that application of a flexible Polyactive® coating simulates the function of the periodontal ligament. The topic of this investigation was to compare the bone-bonding capacity of Polyactive®-coated titanium implants with hydroxylapatite (HA) coated implants. The implants were inserted bilaterally in the edentulous part of the mandibular bone of 12 goats. After 3 weeks, the implants were in close contact with the cortical bone, but no cortical bone reaction or remodelling was observed. After 9 weeks, an extensive bone reaction was seen around the HA and Polyactive®-coated implants and contact was frequently encountered between newly formed bone and the implants. Within the surface of the Polyactive® coating, a considerable amount of calcification was present. After 25 weeks, cortical remodelling was still apparent. A striking finding was the apparent association between osteon formation and calcification within the surface of the Polyactive® layer. Back-scatter analysis of the non-decalcified Polyactive® bone interface showed the presence of a calcium phosphate layer in the implant material that apparently formed a continuity with the mineral matrix of bone, suggesting bone-bonding. In general, it was observed that the bone reactions to HA and Polyactive® were comparable. A swelling of the coating, just beneath the cortical layer (champagne-cork effect) was often seen. This increase in volume, caused by water uptake, might result in a more intimate initial bone/Polyactive® contact, as compared with other implant materials.     

Resonance frequency and removal torque analysis of implants with turned and anodized surface oxides

The present experimental study was designed to address two issues. The first was to investigate whether oxide properties of titanium implants influenced bone tissue responses after an in vivo implantation time of six weeks. If such a result was found, the second aim was to investigate which oxide properties are involved in such bone tissue responses. Screw-shaped implants with a wide range of oxide properties were prepared by electrochemical oxidation methods, where the oxide thickness varied in the range of 200 nm to 1000 nm. The surface morphology was prepared in two substantially different ways, i.e. barrier and porous oxide film structures. The micropore structure revealed pore sizes of 8 microm in diameter, with a range in opening area from 1.27 microm 2 to 2.1 microm 2. Porosity ranged from 12.7% to 24.4%. The crystal structures of the titanium oxide were amorphous, anatase and a mixture of anatase and rutile type. The chemical compositions consisted mainly of TiO2. Surface roughness ranged from 0.96 microm to 1.03 microm (Sa). Each group of test samples showed its own, defined status with respect to these various parameters. The oxide properties of turned commercially pure titanium implants were used in the control group, which was characterized by an oxide thickness of 17.4 +/- 6.2 nm, amorphous type in crystallinity, TiO2 in chemical composition, and a surface roughness of 0.83 microm (Sa). Bone tissue responses were evaluated by resonance frequency measurements and removal torque tests that were undertaken six weeks after implant insertion in rabbit tibia. Implants that had an oxide thickness of approximately 600, 800 and 1000 nm demonstrated significantly stronger bone responses in the evaluation of removal torque values than did implants that had an oxide thickness of approximately 17 and 200 nm (P < 0.05). However, there were no difference between implants with oxide thicknesses of 17 and 200 nm (P = 0.99). It was concluded that oxide properties of titanium implants, which include oxide thickness, micropore configurations and crystal structures, greatly influence the bone tissue response in the evaluation of removal torque values. However, it is not fully understood whether these oxide properties influence the bone tissue response separately or synergistically.     

钛激光气体氮化改性种植体的研究

目的利用激光气体氮化工艺在医用纯钛表面制备TiN改性层,增强医用钛的表面性能,测试改性层的组织、成分和硬度。方法采用2 kW Nd:YAG激光器对置于特制导光可控气氛反应室中的医用纯钛辐照,在纯度为99.995%的氮气中进行激光气体氮化过程。测试分析材料改性前后的显微组织、成分和硬度。结果在医用钛的表面制备了厚度约400 μm的TiN梯度改性层,氮化层与基体界面呈良好的冶金结合。沿着改性层截面方向,显微硬度逐渐减小。结论采用激光气体氮化技术可以在医用钛表面制备致密的TiN增强金属复合材料梯度氮化层,氮化层内部TiN增强相呈梯度分布。     

Effects of a cell adhesion molecule coating on the blasted surface of titanium implants on bone healing in the rabbit femur

PURPOSE: One strategy to improve implant osseointegration is to control the quality of the bone reaction at the implant-bone tissue interface using an implant coated with biologically active substances. The purpose of this study was to investigate the effect of a tetra-cell adhesion molecule (T-CAM) coating composed of 4 cell-adhesion molecules-an arginine-glycine-aspartic acid (RGD) sequence, a proline-histidine-serine-arginine-asparagine (PHSRN) sequence, a tyrosine-histidine sequence (YH), and a glutamic acid-proline-aspartic acid-isoleucine-methionine (EPDIM)-on the rough-surfaced titanium implant on peri-implant bone formation in the rabbit femur with poor local bone conditions and minimal primary stability. MATERIALS AND METHODS: Seven T-CAM-coated (blasted/T-CAM) and uncoated (blasted) implants with a rough surface (hydroxyapatite-blasted; Ra = 1.8 microm) were placed in slightly oversized beds of the metaphyses of the right and left femurs of 7 New Zealand White rabbits with light tactile pressure, and minimal primary stability was obtained. To evaluate the effects of T-CAM coating on the peri-implant bone healing response, histomorphometric analysis was performed 8 weeks after surgery. The 2 groups were compared using the Student t test, with a significance level of P < .05. RESULTS: Compared to uncoated blasted implants at 8 weeks of healing, the blasted/T-CAM implants showed a significantly greater amount of bone-implant contact (BIC; P < .01) and new bone formation in the zones 0 to 100 microm and 0 to 500 microm lateral to the implant surface (P < .05) in the medullary space. CONCLUSION: The T-CAM coating on the rough-surfaced titanium implants significantly enhanced peri-implant bone formation in rabbit femurs with poor local bone condition.