Bone-implant contact on machined and dual acid-etched surfaces after 2 months of healing in the human maxilla

BACKGROUND: Recent clinical studies indicate that an implant with a textured surface may be loaded sooner than traditional healing protocols have recommended. In a previous study, the 6-month bone-implant contact for dual acid-etched and machined implant surfaces was reported to be 72.96% and 33.98%, respectively. In 1991, a minimum of 50% bone-implant contact was considered necessary for loading to ensure long-term survival of the implant. This study evaluated the 2-month bone-implant contact for dual acid-etched and machined implant surfaces to determine if this criterion had been met. METHODS: Custom manufactured implants (2 mm diameter and 5 mm length), having on one side a machined surface and on the other side a dual acid-etched surface, were placed in the posterior maxilla of 11 patients, allowed to integrate for 2 months, then removed using a 4 mm internal diameter trephine with irrigation. Sections were processed and stained for histologic and histomorphometric analysis. The parameters calculated for each section were: bone volume (BV%), actual percent bone-implant contact (BIC%), and expected bone contact (EBC%) as determined from 3 implant images superimposed onto the adjacent bone 150, 500, and 1,000 microm lateral to the actual implant surface and representing the bone-implant contact expected on the day the implant was placed, based on the peri-implant bone volume. RESULTS: Histomorphometric analysis indicated that the mean BV% of 36.77% from all sections was closely matched to the mean EBC% of 34.36% (P<0.001). The analysis showed that after 2 months of healing, the 47.81% BIC% on the dual acid-etched side was statistically higher (analysis of variance, P<0.001) than the 19.00% BIC% on the machined side. In areas of low-density bone (<40% BV%), the difference between the BIC% for the machined and dual acid-etched sides was even greater. Nine of the 11 dual acid-etched sides had a higher BIC% than the EBC% value. In the machined group, 1 of the 11 sides had a higher BIC% value than the EBC% value. The bone surrounding the dual acid-etched surface was a woven bone with thin, connecting peri-implant bony trabeculae projecting into and between the threads. Bone on the machined side was observed mostly contacting the tips of the screw threads. CONCLUSIONS: At 2 months, the mean BIC% for the dual acid-etched group increased 39.14% compared to the EBC% value, while the mean BIC% for the machined group decreased 44.70%. Based on the histomorphometric results of this study, sufficient bone for functional loading of the implant exists on a dual acid-etched surface after 2 months of healing in the posterior maxillary arch.     

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 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.     

Increased bone formation around coated implants

Aim: We hypothesized that coating threaded, sandblasted acid-etched titanium implants with collagen and chondroitin sulphate (CS) increases bone formation and implant stability, compared with uncoated controls.
Materials and Methods: Three different implant surface conditions were applied: (1) sandblasted acid-etched (control), (2) collagen/chondroitin sulphate (low-dose – CS1), (3) collagen/chondroitin sulphate (high-dose – CS2). Sixty 9.5 mm experimental implants were placed in the mandible of 20 minipigs. Bone–implant contact (BIC) and relative peri-implant bone-volume density (rBVD – relation to bone-volume density of the host bone) were assessed after 1 and 2 months of submerged healing. Implant stability was measured by resonance frequency analysis (RFA).
Results: After 1 month, coated implants had significantly more BIC compared with controls (CS1: 68%, p <0.0001, CS2: 63%, p =0.009, control: 52%). The rBVD was lower for all surface conditions, compared with the hostbone. After 2 months, BIC increased for all surfaces. No significant differences were measured (CS1: 71%, p =0.016, CS2: 68%, p =0.67, control: 63%). The rBVD was increased for coated implants. RFA values were 71–77 at implantation, 67–73 after 1 month and 74–75 after 2 months. Differences in rBVD and RFA were not statistically significant.
Conclusions: Data analysis suggests that collagen/CS has a positive influence on bone formation after 1 month of endosseous healing.     

Secondary stability assessment of titanium implants with an alkali-etched surface: a resonance frequency analysis study in beagle dogs

PURPOSE: This study was carried out to quantify the effect of an alkali-modified surface on implant stability during healing using an animal model. MATERIALS AND METHODS: A total of 24 screw-shaped, self-tapping, commercially pure titanium dental implants, divided into a test group (implants with an alkali-modified surface or "biosurface") and a control group (implants with a turned, machined surface) were inserted without pretapping in the tibiae of 3 beagle dogs. The resonance frequency analysis method was used to measure the implant stability quotient (ISQ) 0, 1, 3, 9, and 12 weeks after implantation. The animals were sacrificed after 2, 5, and 12 weeks, and the bone-implant contact (BIC%) was evaluated histomorphometrically. RESULTS: The difference in the osseointegration rates (deltaISQ/deltahealing time) between the implants with alkali-modified surface (biosurface) and those with a turned, machined surface was evaluated as a mean of 0.843 ISQ/week within the first 9 weeks of healing. The mean increase in the secondary implant stability was found to be proportional to the mean increase in the BIC at healing period earlier than 5 weeks. DISCUSSION: The characteristics that differed between the implant surfaces, ie, specific surface area, contact angle, and hydroxylation/hydration, may represent factors that influence the rate of osseointegration and the secondary implant stability. CONCLUSION: The alkali-treated surface enhances the secondary stability in the early stages of healing compared to the turned, machined surface, as a consequence of faster BIC formation.     

Randomized, controlled histologic and histomorphometric evaluation of implants with nanometer-scale calcium phosphate added to the dual acid-etched surface in the human posterior maxilla

BACKGROUND: Placement of dental implants in the posterior maxilla has been associated with higher rates of failure that are due, in part, to the poor bone quality of this region. The purpose of the present study was the histologic and histomorphometric evaluation of the bone around a new implant surface treatment created by a deposition of nanometer-sized calcium phosphate particles added to the dual acid-etched surface. METHODS: One custom-made 2 x 10-mm site evaluation implant (SEI) with this novel treatment surface (test) and one SEI with the dual acid-etched surface without treatment (control) were placed in the posterior maxilla of 15 patients. All SEIs were retrieved after 2 months and evaluated under confocal laser scanning microscopy (CLSM) and by light microscopy for histomorphometric analysis of the bone-implant contact (BIC). RESULTS: Histologic observations in control SEIs showed formation of new bone around the implant surface; however, it was not always in direct contact with the entire perimeter of the threads. The mean BIC was 19% +/- 14.2%. Test SEIs showed peri-implant bone tightly contacting the implant surface and better adapted to the threads. Three-dimensional reconstruction of sections obtained using CLSM showed the intimacy of the contact between bone and test SEI surface through the entire thickness of the specimens. The mean BIC was 32.2% +/- 18.5%. CONCLUSIONS: After 2 months of healing, comparison of the BIC values showed a statistically significant greater mean BIC for test SEIs than for controls. The clinical implications of these results included shortening of the implant healing period and earlier loading protocols.     

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.     

Crestal bone changes at nonsubmerged implants (Camlog) with different machined collar lengths: a histomorphometric pilot study in dogs

PURPOSE: The aim of the present study was to histomorphometrically investigate crestal bone changes at nonsubmerged implants (Camlog) with different machined collar lengths in a dog model. MATERIALS AND METHODS: One-stage insertion of sandblasted acid-etched screw-type implants with machined neck sizes of 1.6 mm (CAM) and 0.4 mm (CAM+) was performed in the mandibles of 4 beagle dogs. Both types of implants were inserted so that the implant shoulder (IC) exceeded the alveolar crest for 0.4 mm. Placement was followed by the connection of standard abutments. The animals were sacrificed after 2 and 12 weeks. Dissected blocks were processed for histomorphometric analysis (eg, distance between IC and the coronal extension of bone-implant contact [CBI], the distance between IC and the apical extension of the inflammatory cell infiltrate, and the percentage of bone-implant contact). RESULTS: Histomorphometric analysis revealed significantly increased mean IC-CBI (CAM: 2.4 +/- 0.3 mm; CAM+: 1.6 +/- 0.1 mm) and BIC (CAM: 77%; CAM+: 80%) values in both groups at 12 weeks. However, mean IC-CBI values were significantly higher in the CAM group (P < .01). An inflammatory cell infiltrate was localized to the implant-abutment interface of both CAM and CAM+ implants, and BC was clearly separated from alCT by a subepithelial connective tissue zone. CONCLUSIONS: Within the limits of the present study, it was concluded that (1) rough-surfaced implant necks reduced crestal bone level changes after 12 weeks of healing, and (2) microbial leakage apparently did not contribute to the marginal bone resorption in either group.     

Bone response to modified titanium surface implants in nonhuman primates (Papio ursinus) and humans: histological evaluation

The aim of this study is a comparative histological and histomorphometrical evaluation of the effect on early bone formation of 2 different implant surfaces: a machined and a new acid-etched implant surface (Leader, Milano, Italy). Ten screw-type microimplants were placed in 5 patients. Each patient received 2 microimplants (2 mm in diameter and 5 mm in length): 1 with a machined surface (control) and 1 with an acid-etched surface (test). The microimplants were retrieved after 60 days of healing with a 4-mm trephine bur and processed for histology. Moreover, 24 regular size implants--12 with a machined surface (control) and 12 with an acid-etched surface (test)--were placed in 2 adult nonhuman primates 3 months after the extraction of premolars and molars. Each animal received 3 machined implants (control) in the right hemimandible and 3 acid-etched implants (test) in the left hemimandible. The same animals received 3 control implants and 3 test implants in the rectus abdominis muscle. After 1 month, the implants were retrieved from the mandible and the rectus abdominis muscle and processed for histology. Histomorphometric evaluation demonstrated a higher bone-to-implant contact in the test implants compared with the controls in both primates (25.55% vs 15.8%) and humans (62% vs 45%). Moreover, in nonhuman primates after 1 month of healing, it was possible to observe a poor osseointegration in the control specimens, while newly formed bone in direct contact with test implants was evident. The rectus abdominis muscle specimens showed that the acid-etched surfaces can stimulate the formation and attachment of new connective and vascular tissues more than machined surfaces can. Implant surface geometry can speed up bone formation by the development of a special microenvironment that promotes angiogenesis. Long-term studies are needed to further test this new acid-etched implant surface.     

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.     

Machined and sandblasted human dental implants retrieved after 5 years: A histologic and histomorphometric analysis of three cases

Objective: Human retrieved implants with an intact bone-implant interface play a pivotal role in validating data obtained from in vitro studies and animal experiments. This study presents a histologic and histomorphometric analysis of peri-implant tissue reactions and of the bone-titanium interface in three machined and sandblasted dental implants retrieved after a 5-year loading period. Method and Materials: Three implants, with an intact bone-implant interface, were found in the Archives of the Implant Retrieval Center of the Dental School of the University of Chieti-Pescara, Chieti, Italy. The three implants had been used in a two-stage submerged procedure and loaded as part of a small prosthetic restoration. One implant had been retrieved because of an abutment fracture, while there was a fracture of the connecting screw in the other two. One implant was in the maxilla (sandblasted surface), and two were in the mandible (one with a machined surface and the other with a sandblasted surface). All implants had been processed for histology. Results: All three implants presented mature, compact, lamellar bone at the interface. Many remodeling areas were present in the peri-implant bone, especially inside the implant threads. The bone was always in close contact with the implant surface. The bone-implant contact percentage of the machined implant was 92.7%, while the two sandblasted implants showed bone-implant contact percentages of 85.9% and 76.6%. Conclusion: The present histologic results confirmed that these implants with different surfaces maintained a good level of osseointegration over a 5-year loading period, with continuous remodeling at the interface, and showed high bone-implant contact percentages. (Quintessence Int 2012;43:287?292).     

Nano-crystalline diamond-coated titanium dental implants – A histomorphometric study in adult domestic pigs

Promising biomaterial characteristics of diamond-coatings in biomedicine have been described in the literature. However, there is a lack of knowledge about implant osseointegration of this surface modification compared to the currently used sandblasted acid-etched Ti-Al6-V4 implants. The aim of this study was to investigate the osseointegration of microwave plasma-chemical-vapour deposition (MWP-CVD) diamond-coated Ti-Al6-V4 dental implants after healing periods of 2 and 5 months.Twenty-four MWP-CVD diamond-coated and 24 un-coated dental titanium-alloy implants (Ankylos^®) were placed in the frontal skull of eight adult domestic pigs. To evaluate the effects of the nano-structured surfaces on bone formation, a histomorphometric analysis was performed after 2 and 5 months of implant healing. Histomorphometry analysed the bone-to-implant contact (BIC). No significant difference in BIC for the diamond-coated implants in comparison to reference implants could be observed for both healing periods. Scanning electron microscopy revealed an adequate interface between the bone and the diamond surface. No delamination or particle-dissociation due to shearing forces could be detected. In this study, diamond-coated dental titanium-alloy implants and sandblasted acid-etched implants showed a comparable degree of osseointegration.     

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.     

Histological evaluation of the Serf EVL evolution implant: a pilot study in a dog model

PURPOSE: The purpose of this study was to compare bone-to-implant contact (BIC) of the one-stage sandblasted surface EVL implant (SERF, Decines, France) with that of the two-stage turned (machined) Branemark Nobel BioCare implant in a dog model system. MATERIALS AND METHODS: Three 1-year old female beagle dogs (canine) were acquired, examined, and quarantined. In dog no. 1, three test implants were placed on one side of the jaw, and four control implants were placed on the other side. In dog no. 2, two test implants were placed in alternation with two control implants on the left and right sides (total 4 tests, 4 controls). In dog no. 3, three test implants were placed on one side and three control implants on the other. After a 3-month period of healing, the dogs were killed and the jaws sectioned for histological preparation. Eleven implants, six tests, and five controls were available for histological evaluation. RESULTS: The percent of BIC for the test implants varied from 24.9% to 61.6%, with an average of 42.7%. The percent of BIC for the control implants varied from 22.1% to 42.6%, with an average of 27.4%. CONCLUSION: The degree of BIC of the EVL implants was on average greater than that of the turned surface of the Branemark implant. However, because of the limited number of implants placed in this pilot study, the results should be interpreted with caution.     

Enhanced bone apposition to a chemically modified SLA titanium surface

Increased surface roughness of dental implants has demonstrated greater bone apposition; however, the effect of modifying surface chemistry remains unknown. In the present study, we evaluated bone apposition to a modified sandblasted/acid-etched (modSLA) titanium surface, as compared with a standard SLA surface, during early stages of bone regeneration. Experimental implants were placed in miniature pigs, creating 2 circular bone defects. Test and control implants had the same topography, but differed in surface chemistry. We created the test surface by submerging the implant in an isotonic NaCl solution following acid-etching to avoid contamination with molecules from the atmosphere. Test implants demonstrated a significantly greater mean percentage of bone-implant contact as compared with controls at 2 (49.30 vs. 29.42%; p = 0.017) and 4 wks (81.91 vs. 66.57%; p = 0.011) of healing. At 8 wks, similar results were observed. It is concluded that the modSLA surface promoted enhanced bone apposition during early stages of bone regeneration.     

Is insertion torque correlated to bone–implant contact percentage in the early healing period? A histological and histomorphometrical evaluation of 17 human‐retrieved dental implants

Objective: A precise and scientifically established method for the evaluation of the bone quality/primary stability is the measure of the insertion torque (IT). The aim of this study was a comparison between the IT values and the bone–implant contact percentage (BIC) of human implants retrieved after a 4/8-week healing period.
Materials: Seventeen implants, all with a sandblasted and acid-etched surface, were evaluated in the present study.
Methods: The implants had been retrieved for different causes, after 4/8 weeks, with a 5 mm trephine bur, and immersed in 10% buffered formalin to be processed for histology.
Results: A not statistically significant correlation was found between IT and BIC ( P ≤0.892).
Conclusions: In the present study on human-retrieved implants, no statistically significant correlation was found between the IT values and BIC. These results could be due to a lack of relationship between bone structure and IT, or to the fact that primary stability may not only be influenced by bone volumetrical density and/or bone trabecular connectivity but also by the thickness and density of the cortical layer. Moreover, the present knowledge of the bone microstructure is not enough to explain the relationship of bone quality and primary implant stability.     

Histomorphometric analysis of the bone-implant contact obtained with 4 different implant surface treatments placed side by side in the dog mandible

PURPOSE: The different implant systems available today present several types of surface treatment, with the aim of optimization of bone-implant contact. This study compared 4 different types of implant surfaces. MATERIALS AND METHODS: The first, second, third, and fourth mandibular premolars were extracted from 5 young adult mongrel male dogs. Ninety days after removal, four 3.75-mm-diameter, 10-mm-long screw-type implants (Paragon) were placed with different surface treatments in mandibular hemiarches. The dogs received 2 implants of each of the following surface treatments: smooth (machined), titanium plasma spray (TPS), hydroxyapatite coating (HA), and sandblasting with soluble particles (SBM). The implants were maintained unloaded for 90 days. After this period, the animals were sacrificed, and the hemimandibles were extracted and histologically processed to obtain non-decalcified sections. Two longitudinal ground sections were made for each implant and analyzed under light microscopy coupled to a computerized system for histomorphometry. RESULTS: The following means were obtained for bone-implant contact percentage: machined = 41.7%, TPS = 48.9%, HA = 57.9%, and SBM = 68.5%. DISCUSSION: The means for all treatments that added roughness to the implant surface were numerically superior to the mean found for the machined surface. However, this difference was statistically significant only between groups SBM and machined (Tukey test, P < .05). CONCLUSIONS: The SBM-treated surface provided a greater bone-implant contact than a machined surface after 90 days without loading in this model.     

Influence of implant microstructure on the osseointegration of immediate implants placed in periodontally infected sites. A histomorphometric study in dogs

The aim of this study was to evaluate the influence of implant microstructure on the osseointegration of immediate implants placed into infected sites. During 12 weeks, periodontitis was induced in six dogs in the areas of the first to fourth mandibular premolars of both sides. The teeth were extracted and the implants were placed immediately. Implant placement was randomly assigned so that for each side in the mandible a different implant surface, a new grit-blasted/acid-etched group 1 or titanium plasma spray surface group 2 was used, totaling 36 implants in the experiment. The animals were killed 12 weeks after implant placement. Two histomorphometric analyses were performed: percentage of bone/implant contact (BIC) and analyses of the bone density in adjacent and distant areas from the implant surface. The results showed that the percentages of BIC were 52.7% and 42.7% for groups 1 and 2, respectively. The bone density analysis revealed that the percentages of bone in the adjacent areas were 66.6% and 58.8%, and in the distant areas from the implants were 58.7% and 55.8% for groups 1 and 2, respectively. The mean differences of BIC were verified through the Mann-Whitney test and differences in bone density through the Kruskal-Wallis test. The differences were not statistically significant (P>0.05). In conclusion, osseointegration of implants placed into a more challenging healing situation such as immediate implants into periodontally compromised sites was successful for both surfaces; however, the grit-blasted/acid-etched surface, although not statistically significant, had a slightly better performance when compared to the titanium plasma spray surface for all the parameters studied.     

Osseointegration of Osseotite and machined-surfaced titanium implants in membrane-covered critical-sized defects: a histologic and histometric study in dogs

The texture of an implant's surface can influence the rate and extent of bone fixation as expressed by the amount of linear bone-to-implant contact (BIC). The purpose of this study was to compare the bone density and linear BIC between Osseotite and machined-surface implants placed in bony defects without graft material and covered by a membrane. Thirty 2 mm diameter, 10 mm length custom implants were prepared for this study having a 'split surface,' with one side having the acid-etched surface and the opposite side having a machined surface. Defects were created in the iliac wing of three adult mongrel dogs where a 6-mm-diameter drill was used to generate a 5-mm-deep defect. The implants were inserted into the center of the defect with 5 mm secured into the bone leaving 5 mm free in the defect with a 2 mm gap between the implant and surrounding bone. Expanded polytetrafluroethelyene membranes were placed over the defect sites stabilized with Biotack pins. The healing times were 2, 3, and 5 months. Histologic and histometric analysis showed significantly lower BIC in the defect region as compared with the portion of implant placed into native bone for both implant surfaces in all groups. There was no difference in BIC values at 2- and 5-month periods between the two surfaces in the regenerated area, while BIC values for Osseotite surfaces were significantly higher than the machined surfaces at 3 months' healing time. Changes in bone density, observed between the three groups, affected correspondingly the BIC values in both implant surfaces, the effect being more pronounced in the Osseotite surface.