Which surface properties enhance bone response to implants? Comparison of oxidized magnesium, TiUnite, and Osseotite implant surfaces

PURPOSE: This study compared the speed and strength of osseointegration and osteoconductivity between an oxidized experimental magnesium (Mg) implant, an oxidized commercially available TiUnite implant, and a dual acid-etched surface Osseotite implant. The aim was to investigate which surface properties enhance bone response to implants, and thereby to test a biochemical bonding theory. MATERIALS AND METHODS: A total of 60 screw implants (20 of each design) were inserted through 1 cortex into the tibiae of 10 rabbits. Surface chemistry, oxide thickness, morphology, crystal structure, and surface roughness were evaluated. After healing times of 3 and 6 weeks, all bone implants were unscrewed with removal torque (RTQ) devices, and the bone specimens were subjected to histomorphometry. RESULTS: RTQ values for Mg, TiUnite, and Osseotite implants were 27.1, 21.3, and 15.4 Ncm, with new bone formation values of 29%, 18%, and 15%, respectively, at 3 weeks. At 6 weeks the RTQ values were 37.5, 36.4, and 21.5 Ncm, with new bone formation values of 39%, 31%, and 26%, respectively. Discussion: Mg implants demonstrated significantly greater RTQ values (P = .008 and P = .0001) and more new bone formation (P = .031 and P = .030) than Osseotite at 3 and 6 weeks, respectively. Mg implants also showed higher RTQ values at 3 weeks and new bone formation at 6 weeks than TiUnite, but neither were significant (P > .05). TiUnite showed significantly higher RTQ values than Osseotite at 6 weeks (P = .001), but was not significant at 3 weeks (P > .05). Osseointegration rate (deltaRTQ/deltaweeks) was significantly faster for Mg (P = .011) and TiUnite (P = .001) implants between 3 and 6 weeks of healing time, but was not significant for Osseotite. CONCLUSIONS: The results indicate that surface chemistry facilitated more rapid and stronger osseointegration of the Mg implants despite their minimal roughness compared to the moderately roughened TiUnite. This suggests potential advantages of Mg implants for reducing high implant failure rates in the early postimplantation stage and in compromised bone, making it possible to shorten bone healing time from surgery to functional loading, and enhancing the possibility of immediate/early loading.     

Surface characterization of three titanium dental implants

PURPOSE: The aim of this study was to evaluate topographically and compositionally the rough surface of 3 different commercial titanium dental implants. MATERIALS: Bio Com Standard, Osseotite Implant, and Fixture MT Osseospeed were analyzed using scanning electron microscopy, atomic force microscopy, and energy dispersive spectroscopy. RESULTS: The scanning electron microscopy and atomic force microscopy analyses showed that the rough surface of Bio Com Standard presents numerous impressions superimposed by sharp pits, of Osseotite Implant many discrete sharp pits, and of Fixture MT Osseospeed a mixed feature appearance. The energy dispersive spectroscopy analysis of the rough implant surfaces revealed a small trace of Si found on the surface of Osseotite Implant. Fixture MT Osseospeed showed a nonhomogeneous distribution of the detected elements. CONCLUSION: The examined implants had a different rough surface topography, which was directly dependent on the type of treatment used. The differences concerning the surface morphology were leading in a characteristic nanotopography, which might influence the biologic activities at the implant-tissue interface. Surface oxygen concentrations also indicated differences in the oxide layer width between the examined implants, being minimal in Osseotite Implant and maximal in Fixture MT Osseospeed.     

Clinical evaluation of dental implants with surfaces roughened by anodic oxidation, dual acid-etched implants, and machined implants

PURPOSE: The purpose of this study was the clinical and radiographic comparison of dental implants with surfaces roughened by anodic oxidation (TiUnite), dual acid-etched implants (Osseotite), and machined implants. MATERIALS AND METHODS: Seventy-four patients (mean age, 52.8 +/- 14.2 years; range, 23 to 80 years; 41 men and 33 women) received 198 dental implants-58 TiUnite implants (25 patients), 52 Osseotite implants (27 patients), and 88 machined implants (22 patients). Clinical measurements and radiographs were evaluated at the time of surgery, at the restorative phase, and 2 years postloading. To account for statistical correlation among multiple implants in the same subject, a "per patient" mode of analysis was conducted. A 1-way analysis of variance of bone loss was conducted by type of implant as well by area of the mouth. In addition, differences in mean bone loss were tested for bone density category, gender, and smoking status using Student t tests. RESULTS: Eighteen TiUnite implants (31.0%) were placed in the maxilla and 40 (69.0%) in the mandible. The Osseotite group included 29 maxillary implants (55.8%) and 23 mandibular implants (44.2%). The machined group included 49 maxillary implants (55.7%) and 39 mandibular implants (44.3%). All 198 implants were considered radiographically and clinically successful. No mobility, signs of infection, or inflammation were detected. DISCUSSION: Implant size, location, bone quality, gender, age, and smoking did not influence the comparative clinical outcomes of the 3 groups (P > .05). A trend toward greater coronal bone loss in the TiUnite group was detected. CONCLUSION: Within the limitations of the present study, TiUnite, Osseotite, and machined dental implants had similar short-term clinical outcomes. No statistically significant differences in bone loss could be detected among implant groups or among the different regions of the oral cavity. The present data underlined the significance of surgical and prosthetic treatment planning.     

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.     

A novel characteristic of porous titanium oxide implants

OBJECTIVE: The anatase form of titanium dioxide (TiO2) is one of the most common crystalline forms of TiO2 and is normally produced by oxidation of titanium via thermal oxidation or anodizing. This crystalline form exhibits photocatalytic activity when it is irradiated with ultraviolet A (UVA) light. The aim of the current study was to analyze the crystal structure of anodic-oxidized TiUnite implants and to confirm the photocatalytic properties in vitro and in vivo. MATERIAL AND METHODS: Cross-sectional observations by transmission electron microscopy were used to determine the surface crystal structure on the TiUnite implant. Subsequently, photocatalytic activity was confirmed by degradation of methylene blue, and hydrophilicity was measured based on the water contact angle. Furthermore, the in vivo effects of the photocatalytic activity of this compound were investigated. RESULTS: An amorphous layer that was about 10 microm thick was observed on the TiUnite implant surface. In the amorphous layer, the anatase form of the crystalline TiO2 was identified. Photocatalytic activity was clearly demonstrated by the bleaching effect of methylene blue under UVA illumination. The contact angle decreased from 44 degrees to 11 degrees after UVA illumination. Although these data suggest increased hydrophilicity for the TiUnite implant, the bone-to-metal contact at 4 weeks was not influenced. CONCLUSION: The anodic-oxidized TiUnite implant has inherent photocatalytic activity. UVA illumination increases the surface hydrophilicity of the implant. However, this increase in hydrophilicity does not improve bone apposition to the implant surface at 4 weeks.     

Histologic evaluation of bone response to oxidized and turned titanium micro-implants in human jawbone

PURPOSE: To evaluate the human bone tissue response to 2 surfaces (oxidized or turned) on commercially available titanium implants. MATERIALS AND METHODS: Screw-type turned (control) and oxidized (test) micro-implants were manufactured in the same manner as commercially available turned and oxidized (TiUnite, Br?nemark System) implants. The thickness of the oxide layer of the test implants was on average 10 microm, corresponding to the oxide thickness of the apical part of the TiUnite implant. Twenty patients received 1 test and 1 control micro-implant each during implant surgery. Before placement, the surface topography of the implants was characterized with an optical confocal laser profilometer. After a mean healing period of 6.6 months in the maxilla and 3.5 months in the mandible, the micro-implants and surrounding tissue were removed with a trephine bur. Histologic sections were produced, and the specimens were analyzed histomorphometrically. RESULTS: Surface roughness and enlargement were greater for the oxidized implants than for the turned implants. All micro-implants, except for 2 controls, were found to be clinically stable at the time of retrieval. Histomorphometric evaluation demonstrated significantly higher bone-to-implant contact for the oxidized implants, whether placed in the maxilla or in the mandible. Significantly more bone was found inside the threaded area for the oxidized implants placed in the mandible and maxilla, but there was no difference between implants with regard to position (maxilla or mandible). DISCUSSION: The stronger bone response to the oxidized implants may have contributed to the fact that 2 control implants but no test implants were lost. The reason for these findings may depend on one or multiple differences of the surfaces between test and control implants: (1) the thicker oxide layer itself, (2) increased surface roughness, (3) different surface morphology in terms of porosity, or (4) change in crystal structure. CONCLUSION: The present histologic study in human jawbone demonstrated a significantly higher bone response for anodic oxidized titanium implants than for implants with a turned surface.     

Oxidized, bioactive implants are rapidly and strongly integrated in bone. Part 1--experimental implants

OBJECTIVES: The study presented was designed to investigate the speed and the strength of osseointegration of oxidized implants at early healing times in comparison which machined, turned implants. MATERIAL AND METHODS: Screw-shaped titanium implants were prepared and divided into two groups: magnesium ion incorporated, oxidized implants (Mg implants, n=10) and machined, turned implants (controls, n=10). Mg implants were prepared using micro-arc oxidation methods. Surface oxide properties of implants such as surface chemistry, oxide thickness, morphology/pore characteristics, crystal structures and roughness were characterized with various surface analytic techniques. Implants were inserted into the tibiae of ten New Zealand white rabbits. After a follow-up period of 3 and 6 weeks, removal torque (RTQ), osseointegration speed (DeltaRTQ/Deltahealing time) and integration strength of implants were measured. Bonding failure analysis of the bone-to-implant interface was performed. RESULTS: The speed the and strength of osseointegration of Mg implants were significantly more rapid and stronger than for turned implants at follow-up periods of 3 and 6 weeks. Bonding failure for Mg implants dominantly occurred within the bone tissue, whereas bonding failure for turned implants mainly occurred at the interface between implant and bone. CONCLUSIONS: Oxidized, bioactive implants are rapidly and strongly integrated in bone. The present results indicate that the rapid and strong integration of oxidized, bioactive Mg implants to bone may encompass immediate/early loading of clinical implants.     

The importance of implant surface characteristics in the replacement of failed implants

PURPOSE: The purpose of the study was to compare the failure rates of implants with either a machined surface or a TiUnite surface used to replace failing implants. MATERIALS AND METHODS: The files of 578 patients, ie, of all patients who were treated at the Department of Periodontology of the University Hospital in Leuven by means of oral implants during 3 recent consecutive years, were analyzed. The implants included in the study had an observation time ranging from 9 to 49 months. All patients had been provided with Br?nemark System implants. Only 2 types of implant surfaces were used: machined and TiUnite. Data collection and analysis focused on the replacement implants, ie, implants placed at sites where the original implants had failed. Data were statistically analyzed by means of Statistica for Windows Software version 5.1; a Fisher exact P test was used. The level of significance was set at P = .05. RESULTS: A total of 41 patients experienced the nonintegration of 58 implants. Of those, 29 implants with a machined surface were replaced by implants with the same surface. Six of the replacement implants failed. Nineteen machined-surface implants were replaced by TiUnite surface implants; 1 failed. Ten TiUnite-surface implants were replaced by implants with the same surface; none failed. The difference in failure rate between machined-surface replacement implants and TiUnite replacement implants was statistically significant (P = .05). DISCUSSION: In addition to the usual patient-related compromising factors, replacement of a failing implant involves the challenge of achieving osseointegration in a nonpristine bone site. In the present study, implants with TiUnite surfaces were associated with fewer failures than machined-surface implants under the same conditions. CONCLUSION: An improved implant surface such as TiUnite may offer a better prognosis when a failed implant has to be replaced at the same site.     

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.     

Analysis of 164 titanium oxide-surface implants in completely edentulous arches for fixed prosthesis anchorage using the pterygomaxillary region

PURPOSE: The purpose of the article was to evaluate the survival rates of TiUnite implants and then compare them to a previous similar study of machined-surface implants. MATERIALS AND METHODS: This report presents the results of 82 consecutive patients treated since the introduction of Nobel Biocare's TiUnite surface. The patients were treated with complete-arch restorations using bilateral pterygomaxillary implants in edentulous maxillae. A total of 840 implants were placed in immediate extraction or healed sites, with a mean of 10 implants placed per patient. RESULTS: In all, 826 of the 840 implants osseointegrated, for a cumulative survival rate (CSR) of 98.3%. One hundred fifty-eight of 164 pterygomaxillary implants successfully osseointegrated, yielding a 96.3% survival rate. DISCUSSION AND CONCLUSION: The results of this complete-arch maxillary prospective study suggest that Br?nemark System TiUnite implants are more predicable than implants with a machined surface. Compared to a similar 1999 study in which the survival rate for machined-surface implants was 92.1%, the present study had a significantly higher survival rate of 98.6% with the TiUnite surface (P < .001). In the pterygomaxillary region, there was an increase of 8% with the TiUnite surface as opposed to the machined surface (P < .001). In addition, 62% of the implants in the present study were immediately loaded, compared to 0% in the machined-surface implant study. The titanium oxide surface appears to assist the healing response of the bone-implant interface.     

Bone contact around acid-etched implants: a histological and histomorphometrical evaluation of two human-retrieved implants

The surface characteristics of dental implants play an important role in their clinical success. One of the most important surface characteristics of implants is their surface topography or roughness. Many techniques for preparing dental implant surfaces are in clinical use: turning, plasma spraying, coating, abrasive blasting, acid etching, and electropolishing. The Osseotite surface is prepared by a process of thermal dual etching with hydrochloric and sulfuric acid, which results in a clean, highly detailed surface texture devoid of entrapped foreign material and impurities. This seems to enhance fibrin attachment to the implant surface during the clotting process. The authors retrieved 2 Osseotite implants after 6 months to repair damage to the inferior alveolar nerve. Histologically, both implants appeared to be surrounded by newly formed bone. No gaps or fibrous tissues were present at the interface. The mean bone-implant contact percentage was 61.3% (+/- 3.8%).     

A meta-analysis examining the clinical survivability of machined-surfaced and osseotite implants in poor-quality bone

PURPOSE: A frequently cited cause of dental implant failure is the inadequate quality of bone found at the implant site during osteotomy preparation. Although bone quality clearly can affect integration rates, additional variables, such as the implant surface conditioning, can also influence long-term implant performance success. The following report examines outcomes of clinical studies that monitored the performance of machined-surfaced implants and dual acid-etched Osseotite (Implant Innovations, Inc., Palm Beach Gardens, FL) implants isolating the effect of bone quality and implant surface conditioning. MATERIALS AND METHODS: Implant data are derived from eight prospective multicenter clinical studies representing 2614 machined-surfaced implants and 2288 Osseotite implants. All implant placement surgeries followed a two-stage surgical approach with an unloaded healing period of 4 to 6 months. Bone quality was assessed by operator perception of resistance during drilling and ranked as dense, normal, or soft. At the time of this analysis, implant follow-up from placement ranged up to 66 months for the Osseotite and 84 months for the machined-surfaced implants. To isolate the effect of bone quality, other baseline variables were compared to ensure equal distribution between groups. Baseline variables included patient demographics, locations, dimensions of implants, and types of restorative cases. Implant performance was analyzed using nonparametric survival analysis (Kaplan-Meier estimator). Cumulative success rates (CSR) were calculated and differences between implant-bone quality combinations were assessed using the log-rank method. RESULTS: For the machined-surfaced implants, the 4-year CSR in all bone sites is 92.7%. For the implants placed in good (dense and normal) bone, the 4-year CSR is 93.6% compared with the 4-year CSR in poor (soft) bone of 88.2% (P < 0.05). For Osseotite implants in all sites, their overall 4-year CSR was 98.4%, 98.4% in good bone, and 98.1% in poor bone. CONCLUSIONS: Bone quality therefore seems to have a definitive impact on machined-surfaced implants, but this effect was not observed in the Osseotite implant series.     

Physico-chemical characterization of the surface of 9 dental implants with 3 different surface treatments

There are many surface treatments applied to dental implants. The aim of the present investigation is to compare the physicochemical characteristics of titanium dental implant surfaces with different surface treatments. 9 dental implants from the same batch were divided in 3 groups and received 3 different surface treatments: machined, acid etched and a new chemical surface treatment called Avantblast. Scanning electron microscopy and confocal microscopy were used to image the treated surfaces, and energy-dispersive spectrometry and X-ray photoelectron spectrometry to provide a chemical characterization of the surfaces. RESULTS: The acid etched and chemical etched surfaces had an increased roughness over the machined one. Surface chemical composition had differences between processes, as the surface with the new treatment presented a reduced level of impurities and increased thickness of the titanium oxide layer. CONCLUSIONS: Surface roughness of titanium dental implants and thickness of the titanium oxide layer can be increased with a suitable surface treatment.     

A human histologic analysis of osseotite and machined surfaces using implants with 2 opposing surfaces

A human histologic study was conducted to compare the percentage of bone-to-implant contact (BIC) at 6 months for Osseotite and machined, commercially pure titanium implant surfaces. To eliminate potential influences caused by differences in bone density at different intraoral locations, 2 mm x 5 mm, threaded, 2-surfaced titanium implants were manufactured; 1 side received the Osseotite surface modification and the opposite side maintained a machined surface. In each of 11 patients, 1 test implant was placed in the posterior maxilla (Types III and IV bone) during conventional dental implant surgery. Following 6 months of unloaded healing, the conventional implants were uncovered, and the test implants and surrounding hard tissue were removed. Histologic analysis indicated that at 6 months of unloaded healing, the mean BIC value for the Osseotite surfaces (72.96% +/- 25.13%) was statistically significantly higher (P < 0.05) than the mean BIC value for the machined surfaces (33.98% +/- 31.04%). When the BIC values for the machined and Osseotite surface pairs were ranked from high to low based on the machined BIC value range of 93% to 0%, the upper 50th percentile (20 surface pairs) mean BIC value was 86.1% +/- 16.7% for the Osseotite surfaces and 60.1% +/- 18.3% for the machined surfaces. The lower 50th percentile (19 surface pairs) mean BIC value was 59.1% +/- 25.3% for the Osseotite surfaces and 6.5% +/- 10.8% for the machined surfaces. Differences between mean BIC values for the 2 surfaces in both the upper and lower 50th percentiles were statistically significant (P < 0.05). The results of this study indicate that in the poorer quality bone typically found in the posterior maxilla, a statistically significantly higher percentage of bone contacts Osseotite surfaces when compared to opposing machined surfaces on the same implant.     

Bone formation at titanium porous oxide (TiUnite) oral implants in type IV bone

BACKGROUND: Several oral implant design advances have been suggested to overcome poor bone quality, an impediment for successful implant treatment. A novel titanium porous oxide (TPO) surface has been shown to offer favorable results in several settings. The objective of this study was to evaluate the local bone formation and osseointegration at TPO-modified implants in type IV bone. METHOD: Three TPO surface-modified implants (TiUnite) were installed into the edentulated posterior maxilla in each of 8 Cynomolgus monkeys. The animals were injected with fluorescent bone labels at 2, 3, 4 and 16 weeks post-surgery and were euthanized at week 16 when block biopsies were collected for histologic analysis. RESULTS: The predominant observation of the TPO implant surface was a thin layer of new bone covering most of the implant threads. Mean (+/-SE) bone-implant contact for the whole study group was 74.1 +/- 4.8%. There was a significant variability in bone-implant contact between animals (P = 0.0003) and between sites of the same animal (P < 0.0001). The variance in bone-implant contact was 30% larger among sites of the same animal than between different animals (187.5 vs. 144.8, respectively). There was a small but significant difference in bone density immediately outside, compared to within the threaded area of the implants (37.1 +/- 3.2% vs. 32.1 +/- 3.2%, P < 0.0001). Bone density outside the implant threads was significantly correlated (beta = 0.682, P < 0.0001) with the bone density within the threaded area. Bone density within the threaded area was significantly correlated (beta = 0.493, P = 0.0002) with bone-implant contact, whereas bone density outside the implant threads did not have a significant effect (beta = 0.232, P = 0.1). CONCLUSIONS: The results suggest that the TPO surface possesses a considerable osteoconductive potential promoting a high level of implant osseointegration in type IV bone in the posterior maxilla.     

Biological responses of anodized titanium implants under different current voltages

The oxide layer of a titanium surface is very stable, and seems to result in excellent biocompatibility and successful osseointegration. The purpose of this study was to investigate the effects of high anodic oxidation voltages on the surface characteristics of titanium implants and the biologic response of rabbit tibiae. Bone tissue responses were evaluated by removal torque tests and histomorphometric analysis. Screw-shaped implants with microthreads were made of commercially pure titanium (Grade II). We prepared anodized implants under 300 V (group I), 400 V (group II), 500 V (group III) and 550 V (group IV). The surface characteristics of specimens were inspected according to three categories: surface morphology, surface roughness and oxide layer thickness. The screw-shaped implants were installed in rabbit tibiae. The removal torque values were measured and histomorphometric analysis was done after 1- and 3-month healing periods. Data indicate that as anodic oxidation voltage increased above 300 V, oxide layer thickness increased rapidly and pore size also increased. The roughness values of the implants increased with voltage up to 500 V, but decreased at 550 V. In the removal torque test, group III showed higher values than groups I and II at a statistically significant level (P < 0.05) after a 1-month healing period. In histomorphometric analysis, groups III and IV, after a 3-month healing period, showed greater bone to implant contact ratios for the total implant surface than did group I (P < 0.05).     

Retrospective clinical study of Osseotite implants: zero- to 5-year results

PURPOSE: Over the last few years, particular attention has been paid to the implant surface and its influence on the formation and maintenance of surrounding bone. The surface of Osseotite implants (Implant Innovations) is produced by a process of thermal etching, which produces a surface with an average roughness that is twice that of machined implants produced by the same manufacturer. In addition to reducing osseointegration time, this factor appears to favor its maintenance over time. This study presents the results of a clinical trial of Osseotite implants. MATERIALS AND METHODS: Five hundred fifty-five Osseotite implants were placed in 244 patients over 5 years, between September 1996 and September 2001. The average follow-up period from implant placement was 26 months (SD 13.1). RESULTS: After the first surgical stage, 8 failures were noted in 6 patients. Life table analysis showed a cumulative survival rate of 98.5%, but no implant was lost after prosthetic loading, with a 100% survival rate both for the mandible and for the maxilla. For the prosthetic loading time, only the implants with more than 12 months of loading were considered, obtaining an average prosthetic loading time of 34 months (SD 9.2). DISCUS SION: The implant survival rate after loading was 100% both in the anterior and posterior regions, and no difference was noted in relation to the different types of prostheses, or length and width of implants. CONCLUSION: The results obtained in this retrospective study population revealed an acceptable survival rate for these implant-supported restorations.     

Osseointegration of Osseotite and machined titanium implants in autogenous bone graft. A histologic and histomorphometric study in dogs

It has been shown that a roughened implant surface results in a higher percentage of bone to implant contact (%BIC) than a machined one. A modified implant surface using a dual thermo-acid etching process (Osseotite) has been introduced and evaluated clinically, mechanically and histologically. The aim of the present study was the histological evaluation of the %BIC between the Osseotite or machined surfaces and the autogenous bone graft. Twenty-two custom-made split-type 10-mm-long implants having two opposing surfaces (Osseotite and machined) were placed between the cranial and caudal dorsal iliac spine at the iliac wing of two adult mongrel dogs. An artificial bone defect was created leaving a 2 mm empty space around the coronal 5 mm of the implants, while the apical 5 mm was stabilized in the existing basal bone. The defects around the implants were filled with particulate autogenous bone graft, covered by an Osseoquest membrane, and left to heal for 5 months. All inserted implants showed a complete integration in the bone tissue. It was found that the resulting %BIC at the Osseotite surface was significantly higher than at the machined one in both regenerated (46.44+/-15.81% vs. 28.59+/-12.04%) and basal bone areas (32.32+/-15.09% vs. 17.25+/-7.40%). The findings of this study imply that the use of autogenous bone graft resulted in significantly higher %BIC values in the regenerated area than in the basal bone area itself, for both implant surfaces.     

Effects of surface topography on the connective tissue attachment to subcutaneous implants

PURPOSE: A major concern for implants that penetrate stratified epithelia is aggressive epithelial proliferation and migration. This epithelial downgrowth on the implant can be inhibited by a firm attachment between the underlying connective tissue and the implant. This study evaluates the connective tissue attachment to titanium implants with various well-defined surface topographies. MATERIALS AND METHODS: Titanium-coated epoxy replicas of polished (PO; R(a) = 0.06 microm), finely blasted (FB; R(a) = 1.36 microm), coarsely blasted (CB; R(a) = 5.09 microm), acid-etched (AE; R(a) = 0.59 microm), coarsely blasted and acid-etched (SLA; R(a) = 4.39 microm), titanium plasma-sprayed (TPS; R(a) = 5.85 microm), machined-like (ML; R(a) = 2.15 microm), and micromachined grooved (GR; V-shaped grooves 30 microm deep) surfaces were implanted subcutaneously in 74 rats for 1 to 11 weeks. Animals were sacrificed weekly. Surfaces were processed for histomorphometric evaluation of connective tissue attachment, capsule thickness, and where applicable, the degree of separation between the tissue and implant. RESULTS: A total of 153 test surfaces were analyzed. Statistical analysis revealed that textured and rough substrata, namely the GR, TPS, AE, CB, and SLA surfaces, exhibited significantly greater (P < .05) connective tissue attachment and thinner fibrous encapsulation when compared to the PO surface. Tissue separation from the implant interface was of significantly lower magnitude and frequency with the rough surfaces than with the PO surface. CONCLUSIONS: The results indicate that rough implant surfaces are associated with stable connective tissue attachment, which has implications for their use in percutaneous and permucosal applications. In addition, data from the AE surface may indicate that the geometry of the surface irregularities can also be a significant determinant of the connective tissue response.     

A multi-centre study of Osseotite implants supporting mandibular restorations: a 3-year report

This multi-centre study evaluated the performance of the Osseotite implant in the mandibular arch. Osseotite implants (n = 688) were placed in 172 patients; 43.5% were placed in the anterior mandible and 66.5% in the posterior mandible. Fifteen per cent of the implants were placed in soft bone, 56.9% in normal bone and 28.1% in dense bone. During placement, 49.9% of the implants were identified as having a tight fit, 48.6% a firm fit and 1.5% a loose fit. About one-third of the implants (32.4%) were short (10 mm in length or less). After 36 months, only 5 implants had been lost, for a cumulative survival rate of 99.3%. The 3-year results of this study indicate a high degree of predictability with placement of Osseotite implants in the mandibular arch.