Histologic evaluation of human bone integration on machined and sandblasted acid-etched titanium surfaces in type IV bone

The aim of this preliminary study was to evaluate the influence of a sandblasted acid-etched surface on bone-implant contact percentage (BIC%) as well as the bone density in the threads area (BD%) in type 4 bone after 2 months of unloaded healing. Five subjects (mean age = 42.6 years) received 2 microimplants each during conventional implant surgery in the posterior maxilla. The microimplants with commercially pure titanium surface (machined) and sandblasted acid-etched surface served as the control and test surfaces, respectively. After a healing period of 2 months, the microimplants and the surrounding tissue were removed and prepared for ground sectioning and histomorphometric analysis. One microimplant with a machined surface was found to be clinically unstable at the time of retrieval. Histometric evaluation indicated mean BIC% was 20.66+/-14.54% and 40.08+/- 9.89% for machined and sandblasted acid-etched surfaces, respectively (P=.03). The BD% was 26.33 +/-19.92% for machined surface and 54.84+/-22.77% for sandblasted acid-etched surface (P=.015). Within the limits of this study, the data suggest that the sandblasted acid-etched implant surface presented a higher percentage of bone-implant contact compared with machined surfaces, under unloaded conditions in posterior maxilla after a healing period of 2 months.     

Surface chemistry effects of topographic modification of titanium dental implant surfaces: 1. Surface analysis

PURPOSE: To analyze the surface composition of 34 different commercially available titanium dental implants. MATERIALS AND METHODS: Surface composition was evaluated by x-ray photoelectron spectroscopy (XPS). Samples were divided into 4 groups, depending on their surface topography (machined, sandblasted, acid etched, or plasma sprayed). RESULTS: Statistical analysis of the data showed a clear relationship between surface composition and topography, which can be easily accounted for by the chemical effects of the surface treatment performed. On average, acid-etched and plasma-sprayed surfaces had higher titanium and lower carbon concentration than machined surfaces. DISCUSSION AND CONCLUSION: Current studies aimed at the evaluation of implants with different topography should not implicitly assume that topography is the only variable controlling the biologic response. Rather, when comparing different topographies, it should be taken into account that surface chemistry may be a variable as well.     

Surface analysis of machined versus sandblasted and acid-etched titanium implants

Initially, implant surface analyses were performed on 10 machined implants and on 10 sandblasted and acid-etched implants. Subsequently, sandblasted and acid-etched implant cytotoxicity (using L929 mouse fibroblasts), morphologic differences between cells (osteoblast-like cells MG63) adhering to the machined implant surfaces, and cell anchorage to sandblasted and acid-etched implant surfaces were evaluated. Results indicated that acid etching with 1% hydrofluoric acid/30% nitric acid after sandblasting eliminated residual alumina particles. The average roughness (Ra) of sandblasted and acid-etched surfaces was about 2.15 microns. Cytotoxicity tests showed that sandblasted and acid-etched implants had non-cytotoxic cellular effects and appeared to be biocompatible. Scanning electron microscopic examination showed that the surface roughness produced by sandblasting and acid etching could affect cell adhesion mechanisms. Osteoblast-like cells adhering to the machined implants presented a very flat configuration, while the same cells adhering to the sandblasted and acid-etched surfaces showed an irregular morphology and many pseudopodi. These morphologic irregularities could improve initial cell anchorage, providing better osseointegration for sandblasted and acid-etched implants.     

Histologic evaluation of early human bone response to different implant surfaces

BACKGROUND: Studies have demonstrated that roughened dental implant surfaces show firmer bone fixation and an increased percentage of bone-to-implant contact (BIC%) compared to commercially pure titanium-surface (machined) implants. Therefore, the purpose of this study was to evaluate the influence of implant-surface topography on human bone tissue after 2 months of unloaded healing. METHODS: Fourteen subjects with a mean age of 46.87 +/- 9.45 years received two microimplants each (2.5 mm in diameter and 6 mm in length), one test (sandblasted acid-etched surface) and one control (machined surface), either in the mandible or in the maxilla. After a healing period of 2 months, the microimplants and surrounding tissues were removed with a trephine bur and prepared for histologic analysis. RESULTS: All microimplants, except for one of the controls, were clinically stable after the healing period. Histometric evaluation indicated that the mean BIC% was 23.08% +/- 11.95% and 42.83% +/- 9.80% for machined and rough microimplant surfaces, respectively (P = 0.0005). The bone area within the threads was also higher for sandblasted-surface implants (P = 0.0005). The mean percentage of bone density did not differ between the two groups (P = 0.578). CONCLUSION: Data from the present histological study suggest that the sandblasted acid-etched implant provides a better human bone tissue response than machined implants under unloaded conditions after a healing period of 2 months.     

Surface properties and biocompatibility of acid-etched titanium

The purpose of this study was to evaluate the effects of acid-etched titanium on the biological responses of osteoblast-like MC3T3-E1 cells. Four types of treatments (polishing, sandblasting, concentrated H2SO4 etching, and concentrated H2SO4 etching with vacuum firing) were carried out on the surfaces of commercially pure titanium (cpTi) disks. MC3T3-E1 cells were then cultured on the treated cpTi surfaces. Through surface roughness measurement and SEM analysis, it was found that the acid-etched surfaces showed higher roughness values than the sandblasted ones. Scanning electron microscope analysis showed that the cells on the disks treated with acid-etching and acid-etching with vacuum firing spread as well as the sandblasted ones. There were no significant differences in cell proliferation and collagen production on cpTi among the four different surface treatments. Based on the results of this study, it was concluded that etching with concentrated sulfuric acid was a simple and effective way to roughen the surface of titanium without compromising its biocompatibility.     

Radiologic follow-up of peri-implant bone loss around machine-surfaced and rough-surfaced interforaminal implants in the mandible functionally loaded for 3 to 7 years

PURPOSE: In this retrospective study, marginal peri-implant bone height around machined and sandblasted/acid-etched interforaminal implants in the mandible was evaluated radiologically at least 3 years after functional loading. MATERIALS AND METHODS: Fifty-one patients, each with 4 interforaminal screw-type implants placed between 1994 and 1998, were included in this study. Of these, 36 patients (70.6%) with a total of 144 implants (76 machined Mk II implants and 68 sandblasted/acidetched Frios implants) were available for follow-up studies. Interforaminal marginal bone loss was evaluated by extraoral rotational panoramic radiographs. In addition, predictive factors such as patient age and sex, nicotine use, implant position, implant life, and site of measurement were recorded, as well as bone loss at surgery (ie, baseline bone loss). Analysis of covariance for repeated measurements was used for statistical analysis. Between-group differences were expressed as least square means +/- standard error. RESULTS: Sandblasted/acid-etched implants showed significantly less marginal bone loss than machine-surfaced implants (2.4 +/- 0.23 mm vs 1.64 +/- 0.27 mm). Implants placed in the anterior of the arch showed significantly more peri-implant bone loss than implants placed in the posterior (P = .0001). DISCUSSION AND CONCLUSIONS: Significantly less long-term peri-implant bone loss was observed for rough implant surfaces compared to machine-surfaced implants. However, it was also demonstrated that both types of implants, in combination with bar-supported overdentures, can produce excellent long-term results in the atrophic edentulous mandible. Mesially placed implants showed more bone resorption than distally positioned implants, independent of surface roughness.     

Sandblasted and acid-etched dental implants: a histologic study in rats

PURPOSE: Current literature has revealed that surface etching of endosseous implants can improve bone-implant contact. The aim of this study was to evaluate the differences in bone-implant contact (BIC) between sandblasted/acid-etched and machined-surface implants. MATERIALS AND METHODS: Thirty-two Sprague-Dawley rats were used in this study. Two implant surfaces, Ecotek (sandblasted/ acid-etched) and machined, were used with 1 implant placed in each tibia of the animals. A total of 64 implants were placed. BIC was evaluated at 5, 15, 30, and 60 days. Histomorphometry of the BIC was evaluated statistically. RESULTS: The sandblasted/acid-etched surface demonstrated a greater BIC percentage than the machined surface. This difference was statistically significant only at 30 and 60 days after healing. DISCUSSION AND CONCLUSION: The sandblasted/acid-etched surface demonstrated a stronger bone response than the machined one at a later period of healing.     

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.     

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.     

The effects of Er:YAG laser treatment on titanium surface profile and osteoblastic cell activity: an in vitro study

Background: Laser light has been proposed as a tool to decontaminate the surface of endosseous implants. The effects of this maneuver on the interactions between cells and surface, however, are poorly known. The goal of the present study is to investigate osteoblast growth and differentiation on three commercially available surfaces untreated or after irradiation by erbium‐doped:yttrium, aluminum, and garnet (Er:YAG) laser at two levels: 150 and 200 mJ/pulse at 10 Hz. Methods: Human osteoblastic Saos‐2 cells were plated on machined, sandblasted and acid‐etched titanium, or titanium plasma‐sprayed disks. The effects of lasing were observed with a scanning electronic microscope, and cell viability was measured by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay. Moreover, we measured the production of the osteoblast‐specific protein osteocalcin and of osteoprotegerin in the supernatants by immunoenzymatic assays. Results: Although no visible changes were observed on machined or titanium plasma‐sprayed disk samples at the tested levels, titanium peaks on sandblasted and acid‐etched titanium disks appeared fused as a consequence of laser irradiation. Interestingly, cell proliferation was slower on irradiated titanium at both intensities on all the surfaces. Cell differentiation, as assessed by osteocalcin production, was generally unaffected by laser treatment, whereas the production of osteoprotegerin was decreased on all the surfaces irradiated at the intensity of 200 mJ/10Hz. Conclusions: These results indicate that Er:YAG laser at energy levels used in this study can alter the surface profile of titanium implants and these changes may negatively affect the viability and the activity of osteoblastic cells. Therefore, Er:YAG lasers should be used with caution on titanium surfaces.     

Histomorphometric evaluation of six dental implant surfaces after early loading in augmented human sinuses

This study investigated the bone-to-implant contact (BIC) and osteoconductive capacity (OC) of 6 different implant surfaces after early loading in humans. Two implants with different surfaces were placed side-by-side in the grafted (n= 5) and nongrafted (n = 1) sinuses of 3 volunteers. Single-tooth restorations were delivered 60 days later. After 6 months of full occlusal loading, implants were retrieved in block sections for histomorphometric analysis. One implant (acid etched) placed in grafted bone failed when loaded. There were no other complications. In grafted bone, the microtextured surface achieved the highest BIC value (94.08%), followed by the oxidized (77.32%), hydroxyapatite (HA) (74.51%), sandblasted and acid-etched (51.85%), and titanium plasma-sprayed (TPS) (41.48%) surfaces. In native bone, the acid-etched surface achieved a higher BIC value (69.03%) than the HA surface (59.03%). The highest OC value in grafted bone was exhibited by the microtextured surface (34.31%), followed by the HA (28.62%), sandblasted and acid-etched (25.08%), oxidized (17.55%), and TPS (-20.47%) surfaces. The HA surface exhibited a higher OC value (30.39%) in native bone compared with the acid-etched surface (24.0%). As a whole, highest BIC and OC values were exhibited by the microtextured surface, and lowest values were exhibited by the TPS surface. All other surfaces demonstrated excellent BIC (>50%) but varied in OC (range = 17.55%-28.62%). These findings are tempered by the limited scope and sample size of the study and should be considered preliminary. More research is needed to determine the impact of implant surface texture on BIC and OC.     

Improvement of osseointegration of titanium dental implant surfaces modified with CO ions: a comparative histomorphometric study in beagle dogs

The aim of this study was to compare carbon-oxygen (CO) ion implantation as a surface treatment with diamond-like carbon and commercially treated implants, including double acid-etched (Osseotite), oxidized (TiUnite) and sandblasted and acid-etched (SLA), using machine-turned titanium implants as control. A total of 72 dental implants divided into 6 groups were placed in the mandibles of 12 beagle dogs. Evaluation was performed by conventional light transmission microscopy and environmental scanning electron microscopy (ESEM). The histological results obtained via ESEM demonstrated bone-implant contact percentage (%BIC) for implants treated with CO ion implantation of 61% and 62% at 3 and 6 months, respectively. At the same time points, the values were 48% and 45% for double acid-etched, 46% and 52% for sandblasted and acid-etched, 55% and 46% for oxidized, and 33% and 49% for machine-turned titanium control implants. Values of %BIC were statistically significantly higher in implants treated with CO ion implantation compared to the commercially treated implant group (p=0.002 and p=0.025) and the control implants (p=0.001 and p=0.032) at 3 and 6 months, respectively. No significant differences were observed between the three groups of commercially treated implants. The larger %BIC of the ion-implanted group was observable at an early stage.     

Early endosseous integration enhanced by dual acid etching of titanium: a torque removal study in the rabbit

Textured implant surfaces are thought to enhance endosseous integration. Torque removal forces have been used as a biomechanical measure of anchorage, or endosseous integration, in which the greater forces required to remove implants may be interpreted as an increase in the strength of bony integration. The purpose of this study was to compare the torque resistance to removal of screw-shaped titanium implants having a dual acid-etched surface (Osseotite) with implants having either a machined surface, or a titanium plasma spray surface that exhibited a significantly more complex surface topography. Three custom screw-shaped implant types - machined, dual acid-etched (DAE), and titanium plasma sprayed (TPS) - were used in this study. Each implant surface was characterized by scanning electron microscopy and optical profilometry. One DAE implant was placed into each distal femur of eighteen adult New Zealand White rabbits along with one of the other implant types. Thus, each rabbit received two DAE implants and one each of the machined, or TPS, implants. All implants measured 3.25 mm in diameter x 4.00 mm in length without holes, grooves or slots to resist rotation. Eighteen rabbits were used for reverse torque measurements. Groups of six rabbits were sacrificed following one, two and three month healing periods. Implants were removed by reverse torque rotation with a digital torque-measuring device. Three implants with the machined surface preparation failed to achieve endosseous integration. All other implants were anchored by bone. Mean torque values for machined, DAE and TPS implants at one, two and three months were 6.00+/-0.64 N-cm, 9.07+/-0.67 N-cm and 6.73+/-0.95 N-cm; 21.86+/-1.37 N-cm, 27.63+/-3.41 N-cm and 27.40+/-3.89 N-cm; and 27.48+/-1.61 N-cm, 44.28+/-4.53 N-cm and 59.23+/-3.88 N-cm, respectively. Clearly, at the earliest time point the stability of DAE implants was comparable to that of TPS implants, while that of the machined implants was an order of magnitude lower. The TPS implants increased resistance to reverse torque removal over the three-month period. The results of this study confirm our previous results that demonstrated enhanced bony anchorage to dual acid-etched implants as compared to machined implants. Furthermore, the present results indicate that dual acid etching of titanium enhances early endosseous integration to a level which is comparable to that achieved by the topographically more complex TPS surfaces.     

Optimum surface properties of oxidized implants for reinforcement of osseointegration: surface chemistry, oxide thickness, porosity, roughness, and crystal structure

PURPOSE: To investigate detailed surface characterization of oxidized implants in a newly invented electrolyte system and to determine optimal surface oxide properties to enhance the bone response in rabbits. MATERIALS AND METHODS: A total of 100 screw-type titanium implants were prepared and divided into 1 control group (machine-turned implants) and 4 test groups (magnesium ion-incorporated oxidized implants). Forty implants were used for surface analyses. A total of 60 implants, 12 implants from each group, were placed in the tibiae of 10 New Zealand white rabbits and measured with a removal torque test after a healing period of 6 weeks. RESULTS: For the test groups, the oxide thicknesses ranged from about 1,000 to 5,800 nm; for the control group, mean oxide thickness was about 17 nm. The surface morphology showed porous structures for test groups and nonporous barrier film for the control group. Pore diameter ranged from < or = 0.5 microm to < or = 3.0 microm. In regard to surface roughness, arithmetic average height deviation (Sa) values varied from 0.68 to 0.98 microm for test implants and 0.55 microm for control implants; developed surface ratio (Sdr) values ranged from 10.6% to 46% for the test groups and were about 10.6% for the control group. A mixture of anatase and rutile-type crystals were observed in the test groups; amorphous-type crystals were observed in the control group. After a healing period of 6 weeks, removal torque measurements in all 4 test groups demonstrated significantly greater implant integration as compared to machine-turned control implants (P < or = .033). DISCUSSION: Determinant oxide properties of oxidized implants are discussed in association with bone responses. Of all surface properties, RTVs were linearly increased as relative atomic concentrations of magnesium ion increase. CONCLUSIONS: Surface properties of the oxidized implants in the present study, especially surface chemistry, influenced bone responses. The surface chemistry of the optimal oxidized implant should be composed of approximately 9% magnesium at relative atomic concentration in titanium oxide matrix and have an oxide thickness of approximately 1,000 to 5,000 nm, a porosity of about 24%, and a surface roughness of about 0.8 microm in Sa and 27% to 46% in Sdr; its oxide crystal structure should be a mixture of anatase- and rutile-phase crystals.     

Oral implant surfaces: Part 2--review focusing on clinical knowledge of different surfaces

PURPOSE: This article reviews clinical knowledge of selected oral implant surfaces. MATERIALS AND METHODS: The surfaces most commonly used in clinical practice, marketed by the five largest oral implant companies, are identified; their clinical documentation was scrutinized following a strict protocol. Experimental knowledge of the surfaces is briefly summarized. Retrospective, prospective, and comparative clinical studies were analyzed separately, as were studies of implants in conjunction with bone grafts. RESULTS: TiUnite anodized surfaces are clinically documented in 1- to 2-year follow-up studies at best, with failures at about 3%. Sandblasted and acid-etched SLA surfaces are documented with good clinical results for up to 3 years. Osseotite dual acid-etched implants are documented with good clinical results for up to 5 years. Frialit-2 sandblasted and etched implants are positively documented for about 3 years in one study only. The Tioblast implant is the only design documented for survival over 10 years of follow-up and success over 7 years of follow-up. CONCLUSION: Generally, oral implants are introduced clinically without adequate clinical documentation. Implant companies initiate clinical documentation after product launch. The standards of clinical reporting have improved over the years. Proper long-term reports have been published for only one surface, Tioblast.     

Effect of bioactive glass air-abrasion on the wettability and osteoblast proliferation on sandblasted and acid-etched titanium surfaces

The aim of this study was to evaluate the hydrophilicity, surface free energy, and proliferation and viability of human osteoblast-like MC3T3-E1 cells on sandblasted and acid-etched titanium surfaces after air-abrasion with 45S5 bioactive glass, zinc-containing bioactive glass, or inert glass. Sandblasted and acid-etched titanium discs were subjected to air-abrasion with 45S5 bioactive glass, experimental bioactive glass (Zn4), or inert glass. Water contact angles and surface free energy were evaluated. The surfaces were studied with preosteoblastic MC3T3-E1 cells. Air-abrasion with either type of glass significantly enhanced the hydrophilicity and surface free energy of the sandblasted and acid-etched titanium discs. The MC3T3-E1 cell number was higher for substrates air-abraded with Zn4 bioactive glass and similar to that observed on borosilicate coverslips (controls). Confocal laser scanning microscopy images showed that MC3T3-E1 cells did not spread as extensively on the sandblasted and acid-etched and bioactive glass-abraded surfaces as they did on control surfaces. However, for 45S5- and Zn4-treated samples, the cells spread most at the 24 h time point and changed their morphology to more spindle-like when cultured further. Air-abrasion with bioactive glass and inert glass was shown to have a significant effect on the wettability and surface free energy of the surfaces under investigation. Osteoblast cell proliferation on sandblasted and acid-etched titanium discs was enhanced by air-abrasion with 45S5 bioactive glass and experimental Zn4 bioactive glass compared with air-abrasion with inert glass or no air-abrasion.     

Supra- and subgingival biofilm formation on implant abutments with different surface characteristics

PURPOSE: The aim of the present study was to establish a noninvasive method for quantitative analysis of supra- and subgingival biofilm formation on dental implants considering different surface modifications. MATERIALS AND METHODS: Patients of both sexes were included. They had to be in generally good health, partially edentulous, and the recipient of at least 1 screw-type implant with an abutment possessing supra- and subgingival areas. Healing abutments were inserted for 14 days. The abutment surfaces were divided into quadrants that were sandblasted, ground, acid-etched, and untreated (with the latter surface as a control). Biofilm formation on the healing abutments was analyzed using scanning electron microscopy, including secondary-electron and Rutherford backscattering-detection methods. Calculation of biofilm-covered surfaces was performed depending on grey-values, considering supra- and subgingival areas. After calculating absolute and relative biofilm-covered surfaces depending on localization, the influence of surface modification on biofilm formation was analyzed. RESULTS: Fifteen healing abutments were inserted in 11 patients. In all surface properties plaque adhesion in supragingival areas was significantly higher (17.3% +/- 23.1%) than in subgingival areas (0.8% +/- 1.0%). Biofilm accumulation in supragingival areas was significantly increasing by higher surface roughness, whereas this influence was not detected in subgingival areas. CONCLUSION: The described method is valuable for investigation of supra- and subgingival biofilm adhesion on surface-modified implant abutments. There was a significant influence of surface localization (supra- and subgingival) as well as surface modification on biofilm formation.     

A multi-center study comparing dual acid-etched and machined-surfaced implants in various bone qualities

BACKGROUND: A major reason for the success of modern dental implant systems has been the development of implant designs that enhance direct bone-implant interface. Surface roughness has been a factor in this success and different systems have utilized very different implant surface roughness. The major purpose of this study was to evaluate 2 similar implants with different surface roughness characteristics. METHODS: Two similarly designed, screw-type, commercially pure titanium implants, one dual acid-etched (DAE) and the other machined-surfaced (MS), were compared in this prospective, randomized-controlled, multi-center study, in which a total of 97 patients were enrolled at a private dental practice or a university dental clinic. Both implant types were placed in each patient using a 2-stage approach with a conventional 4- to 6-month healing period. Implants supported fixed prostheses, hybrid prostheses, and overdentures as dictated by the individual patient's need. All of the cases were followed using clinical and radiographic examinations. Criteria of success were the absence of peri-implant radiolucency, mobility, and persistent signs or symptoms of pain or infection. RESULTS: Of the 432 implants (247 dual acid-etched, 185 machined-surfaced), 36 implants (12 dual acid-etched and 24 machined-surfaced) have failed. The pre-loading integration success rate of the dual acid-etched implants (95.0%) was statistically higher (P < 0.01) than the success rate of the machined-surfaced implants (86.7%). At 36 months, the cumulative success rates (CSR) are 95.0% for the dual acid-etched implants and 86.7% for the machined-surfaced implants. CONCLUSIONS: The difference in success rates is most likely attributed to the acid-etched surface characteristics. The greatest performance difference is observed in the conditions of poor quality or soft bone where the 3-year post-loading CSR are 96.8% (dual acid-etched) and 84.8% (machined-surfaced).     

Spreading of epithelial cells on machined and sandblasted titanium surfaces: an in vitro study

BACKGROUND: The purpose of this investigation was to determine the influence of the surface structure of dental implants on epithelial cell spreading and growth in vitro. Cell morphology on machined and sandblasted titanium surfaces was investigated. METHODS: A total of 10 machined and 10 sandblasted discs and 10 glass coverslips were used for the present study. Samples were analyzed using scanning electron microscopy (SEM) and the cell spreading area was determined using a video image analysis system. RESULTS: After 24 hours incubation, keratinocytes grown on sandblasted titanium samples displayed numerous, long, and branched or dendritic filopodia closely adapted to the surface roughness. Filopodia varied from 3 to 12 microm in length and 0.1 to 0.3 microm in width. Cells cultured on a machined surface did not present such cytoplasmic extensions and displayed a round morphology. Keratinocytes seeded on glass coverslips were flat and edged by filopodia (maximum length 7 to 8 microm) on the spreading site of the cluster. Though cell morphology is comparable with that observed on sandblasted specimens, cytoplasmic extensions suggestive of strong adhesion and spreading attitude were less pronounced. CONCLUSION: These results indicate that sandblasted surfaces are the optimal substrata for epithelial cell adhesion and spreading.     

不同表面处理方法对CAD/CAM氧化锆种植体表面显微形貌的影响研究

目的：：研究采用不同表面处理方法对CAD/CAM氧化锆种植体表面显微形貌特征及粗糙度的影响。方法：通过CAD/CAM技术加工氧化锆圆盘与一段式氧化锆种植体( Y-TZP, WIELAND),根据表面处理方式分为终烧结表面、喷砂表面及喷砂加热酸蚀处理表面;标准对照组选用BEGO钛种植体表面。各组圆盘试件及种植体用扫描电子显微镜及Keyence 3D激光显微形貌测量显微镜进行表面显微形貌观察与测量。采用单因素方差分析比较各组统计学差异。结果：各组CAD/CAM氧化锆试件表面显微形貌观察显示,喷砂后表面出现边缘锐利的凹坑及沟槽;喷砂加热酸蚀处理后,氧化锆表面可见纳米级的微小孔隙及沟纹。氧化锆种植体粗糙度测量结果显示：终烧结组的表面粗糙度值(Ra=0.69μm)显著低于其他3组(P<0.001),喷砂组Ra值(Ra=1.30μm)显著低于喷砂加热酸蚀组(Ra=1.49μm)及BEGO钛种植体组(Ra=1.57μm)(P<0.01),而喷砂加热酸蚀组与BEGO钛种植体组则无显著差异(P=0.196)。结论：CAD/CAM氧化锆试件终烧结后喷砂或喷砂加热酸蚀处理均可获得较为理想的表面粗糙度,热酸蚀处理能够改变氧化锆表面的纳米级微观结构。