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.     

A meta-analysis evaluating the risk for implant failure in patients who smoke

Failure of dental implants to achieve osseointegration is often attributed to patient baseline variables, such as smoking. This meta-analysis examines outcomes of clinical studies that monitored the performance of machined-surfaced and Osseotite, implants; the analysis also isolates the effect of smoking. The implant data for the machined-surfaced implants are derived from three prospective multicenter studies (n = 2,614) and from six prospective studies (n = 2,274) for the Osseotite implants. All implant placement surgeries followed a two-stage surgical approach with an unloaded healing period of 4 to 6 months. An evaluation of the data sets (i.e., smokers vs nonsmokers) was first performed to determine the existence of imbalance in baseline variables, including patient demographics, bone quality, location, dimensions, and types of prostheses. Analysis of the distributions of these baseline variables showed similar proportionalities and therefore qualified the data sets for comparison of the cumulative success rates (CSR) of the implants on the basis of smoking. For the 2,117 nonsmoking, machined-surfaced implants, the 3-year CSR is 92.8%; for the 492 implants in the smoking group, the CSR is 93.5%. The 3-year CSR for 1,877 nonsmoking Osseotite implants is 98.4%; for the 397 smoking implants it is 98.7%. No difference is observed between the smoking groups and the nonsmoking groups in these patient populations. There is, however, a clinically relevant difference observed between the two implant types.     

Immediate occlusal loading of double acid-etched surface titanium implants in 41 consecutive full-arch cases in the mandible and maxilla: 6- to 74-month results

BACKGROUND: The high success rate of dental implants has changed the quality of life for many patients. Immediate loading finds its application in some clinical cases and certainly adds another modality of treatment for the implant patient. Starting with a few implants immediately loaded with a bar overdenture in the mandible, the concept of immediate loading evolved to loading multiple implants in both the maxilla and mandible. METHODS: In this investigation, 41 consecutive patients who needed full-arch restorations were treated with 343 double acid-etched surface implants between May 1998 and March 2004. The sample included smokers and bruxers. Twenty-three mandibular and 26 maxillary cases were treated, loading the implants within 48 hours, by using resin provisional prostheses, metal-reinforced provisional prostheses, or definitive prostheses (metal-acrylic or metal-ceramic). All implants were followed for 12 to 74 months. Follow-up consisted of clinical as well as radiographic examination. Furthermore, resonance frequency analysis was done in most of the implants during the last 2 years. RESULTS: The success rate obtained was 99.42% (only two mandibular implants that are still surviving were considered failures). The bone level was measured every year. The average radiographic bone level change was 0.56 mm at 12, 0.76 mm at 24, 0.84 mm at 36, 0.82 mm at 48, 0.83 mm at 60, and 0.94 mm at 72 months. CONCLUSION: A high success rate can be achieved when double acid-etched surface implants are immediately loaded with fixed full-arch restorations in the maxilla and mandible.     

The single-tooth implant: a viable alternative for single-tooth replacement

BACKGROUND: The use of dental implants for single-tooth replacement cases introduces a challenge to the performance of these restorations. Clinical data suggest that single-tooth implant restorations do not benefit from lateral support from the surrounding dentition as do bridged implants, and that these restorations are subjected to greater masticatory forces. Therefore, single-tooth implants are exposed to an increased risk of failure. This prospective clinical trial was designed to evaluate the cumulative success rate of dual acid-etched single-tooth replacement implants in two clinical centers. METHODS: The study protocol included 59 patients between 19 and 73 years. Implants were evaluated for mobility, infection, and crestal bone loss from 30.9 to 60 months. RESULTS: Seventy-one (71) implants were placed in 59 patients, 20 male and 39 female. Forty-seven (47) were placed in the maxilla and 24 in the mandible. The percentages of anterior and posterior implants were 45.1% and 54.9%, respectively. A total of 13 (18.4%) implants were placed in soft, poor quality (Type IV) bone. Beginning 1 month post-implant placement, cases were followed for 30.9 to 60 months with a mean follow-up of 45.9 months. One implant failed (peri-implant infection) yielding an overall success rate of 98.6%. CONCLUSIONS: This success rate for single-tooth replacement dual acid-etched implants compares favorably with bridged implants and with success rates of other single-tooth implant studies. Dual acid-etched implants performed well even under conditions of poor quality bone, where concomitant bone augmentation was performed, and when used for immediate replacement of extracted teeth.     

A macro- and nanostructure evaluation of a novel dental implant

Success in implant dentistry also comes from the implant macrodesign and nanostructure of its surface. Titanium implant surface treatments have been shown to enhance osseointegration, maximize bone healing, and bone-to-implant contact for predictable clinical results. The aim of the study, was to evaluate the geometric macrodesign and the surface nanostructure of a novel dental implant full contact covering (FCC) obtained by electrochemical procedures. FCC implants were analyzed by scanning electronic microscope, profilometer, and x-ray photoelectron spectroscopy and compared with commercial sandblasted and sandblasted, large-grit acid-etched dental implants. Sample analysis allowed to distinguish the different implant macrodesigns, the step and the profile of the coils that cover the fixture, and the surface characteristics. FCC implant showed novel macro-characteristic of crestal module, coils, and apical zone compared with sandblasted and sandblasted and acid-etched dental implants. Moreover, the FCC nanostructure surface showed roughness values statistically higher than the 2 other surfaces, with a more homogeneity in a peaks and valleys arrangement. Finally, the x-ray photoelectron spectroscopy analysis detected differences between the examined surfaces, with the presence of several contaminants according to the different treatment procedures. Research on new macrostructures and nano morphology should result in a better qualitative and quantitative osseointegration response, with a predictability of the clinical results and long-term success of the implants.     

Immediate loading of osseotite implants: two-year results

The high success rate of dental implants has changed the quality of life for many patients. Immediate loading finds its application in some clinical cases and certainly adds another modality of treatment for the implant patient. Starting with a couple of implants placed in the mandible and immediately loaded within 72 hours after surgical placement with an overdenture, this concept evolved to immediately loading multiple implants in both the maxilla and the mandible. In this investigation, 11 consecutive patients were treated with 87 screw-shaped endosteal acid-etched, Osseotite implants (3i, Implant Innovations, Inc., Palm Beach Gardens, FL) between June 1998 and June 1999. Two mandibular and two maxillary cases received screw-retained provisional prostheses the day of surgery. Three mandibular and four maxillary cases were loaded 48 hours after surgery with the final screw-retained, porcelain-fused-to-metal prostheses. All implants were followed for 2 to 3 years. Follow-up consisted of clinical as well as radiographic examination. All implants were successful. There was no implant mobility or periimplant radiolucency. The bone level was measured at the 12th and 24th months. The average radiographic bone level from the implant platform to the first bone-to-implant contact was 0.654 mm at the 12th month and 0.946 mm at the 24th month. We conclude that a high success rate can be achieved when implants with a hybrid surface, machined/acid-etched, are immediately loaded within 48 hours after surgical placement in the maxilla and the mandible.     

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%).     

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.     

Bone response to immediate loading through titanium implants with different surface roughness in rats

Because of its high predictability of success, implant therapy is a reliable treatment for replacement of missing teeth. The concept of immediate implant loading has been widely accepted in terms of early esthetic and functional recovery. However, there is little biological evidence to support this concept. The objective of this study was to examine the interactive effects of mechanical loading and surface roughness of immediately loaded titanium implants on bone formation in rats. Screw-shaped anodized titanium implants were either untreated (smooth) or acid-etched. Two implants were inserted parallel to each other in the tibiae of rats, and a closed coil spring (2.0 N) was immediately applied. Trabecular and cortical bone around both implants was analyzed using microtomographic images, and a removal torque test was performed at weeks 1, 2, and 4. Immediate loading of acid-etched implants resulted in significant decreases in bone mineral density, contact surface area, and cortical bone thickness. These effects were not observed after immediate loading of smooth implants. Conversely, loading did not influence acid-etched implant fixation; however, smooth implant fixation at week 1 was significantly reduced. These results imply that surface roughness regulates bone response to mechanical stress and that immediate loading might not inhibit osseointegration for smooth and rough implants in the late healing stages.     

Cantilever fixed prostheses utilizing dental implants: a 10-year retrospective analysis.

OBJECTIVE: The dental literature has been unclear about long-term success of fixed cantilever prostheses supported by dental implants. The disappointing results reported when cantilever fixed partial dentures (FPDs) are supported with natural teeth are not directly applicable to implant cantilever FPDs. This article reports on 10 years of implant-retained fixed prostheses primarily in the maxillary arch using the ITI dental implant system. METHOD AND MATERIALS: Sixty cantilever prostheses using 115 ITI dental implants on 36 patients were placed and monitored over a 10-year period. RESULTS: No implant fractures, abutment fractures, porcelain fractures, prosthesis fractures, soft tissue recession, or radiographic bone loss were recorded. All 60 cantilevered prostheses remain in satisfactory function. CONCLUSION: Positive, long-term results, using implant-retained cantilever FPDs can be achieved by: (1) using a rough surface implant of 4.1 mm or greater; (2) using an implant/abutment design that reduces stacked moving parts and reduces the implant-to-crowns ratio; and (3) using a cementable prosthesis design that eliminates the need for occlusal screw retention.     

A clinical report on the 18-month cumulative survival rates of implants and implant prostheses with an internal connection implant system

Titanium implants have been successful in both dentulous and edentulous patients. The original Br?nemark titanium implants were introduced with external hex connections between implants and abutments. Successes and failures/complications with both the biology and mechanics of this connection system have been reported. In an attempt to improve the predictability and success of implant/abutment connections, internal connections between implants and abutments were developed significantly differently from external implant/abutment connections in terms of size, surface area, and geometry. Forty-five consecutive partially edentulous patients were treated with 83 implants (Osseotite Certaina). The implants were allowed to heal for at least 8 weeks without occlusal loading. All were restored with single, nonsplinted restorations. The implants were loaded with fully functional occlusions for at least 1 year. Recall appointments were scheduled at 1, 6, 12, 18, 24, and 36 months after implant placement. Eighty-two of the 83 implants were clinically stable and considered to be osseointegrated 18 months after occlusal loading for a cumulative survival rate (CSR) (implants) of 100%. All of the abutment screws and restorations were non-mobile 18 months after occlusal loading for a CSR (prostheses) of 100%. This internal implant/abutment connection was clinically successful and should benefit restorative dentists involved in implant dentistry by decreasing the number of maintenance visits and problems associated with dental implant treatment.     

Short dental implants: a systematic review

Growing evidence has suggested the utility of short dental implants for oral reconstructive procedures in clinical situations of limited vertical bone height. The aim of this review was to systematically evaluate clinical studies of implants < 10 mm in length, to determine short implant-supported prosthesis success in the atrophic jaw. Implant survival, incidence of biological and biomechanical complications, and radiographic peri-implant marginal bone loss were evaluated. Screening of eligible studies, quality assessment, and data extraction were conducted by two reviewers independently. Meta-analyses were performed by the pooling of survival data by implant surface, surgical technique, implant location, type of edentulism, and prosthetic restoration. Two randomized controlled trials and 14 observational studies were selected and analyzed for data extraction. In total, 6193 short-implants were investigated from 3848 participants. The observational period was 3.2 ± 1.7 yrs (mean ± SD). The cumulative survival rate (CSR) was 99.1% (95%CI: 98.8-99.4). The biological success rate was 98.8% (95%CI: 97.8-99.8), and the biomechanical success rate was 99.9% (95%CI: 99.4-100.0). A higher CSR was reported for rough-surfaced implants. The provision of short implant-supported prostheses in patients with atrophic alveolar ridges appears to be a successful treatment option in the short term; however, more scientific evidence is needed for the long term.     

Five-year results of fixed implant-supported rehabilitations with distal cantilevers for the edentulous mandible

Objectives: The purpose of this study was to evaluate the survival rate, success rate and primary complications associated with mandibular fixed implant‐supported rehabilitations with distal cantilevers over 5 years of function. Material and methods: In this prospective multi‐center trial, 45 fully edentulous patients were treated with implant‐supported mandibular hybrid prostheses with distal extension cantilevers. Data were collected at numerous time points, including but not limited to: implant placement, abutment placement, final prosthesis delivery, 3 months and 5 years post‐loading. Biological, implant and prosthetic parameters defining survival and success were evaluated for each implant including: sulcus bleeding ndex (SBI) at four sites per implant, width of facial and lingual keratinized gingiva (mm), peri‐implant mucosal level (mid‐facial from the top of the implant collar, measured in mm), modified plaque index (MPI) at four sites per implant, mobility and peri‐implant radiolucency. Survival was defined as implants or prostheses that did not need to be replaced. Success rate was defined as meeting well‐established criteria that were chosen to indicate healthy peri‐implant mucosa osseointegration, prostheses success and complications. Results: A total of 237 implants in 45 completely edentulous patients were included in the study. In each patient, four to six implants were placed to support hybrid prostheses with distal cantilevers. Cantilevers ranged in length from 6 to 21 mm, with an average length of 15.6 mm. The ages of the patients ranged from 34 to 78 with a mean age of 59.5 years. The survival rate of implants was 100% (237/237) and for prostheses 95.5% (43/45). The overall treatment success rate was calculated as 86.7% (39/45). Of the six patients that have not met the criteria for success, two patients required replacement of the entire prosthesis and four patients presented >four complications events. Conclusion: Fixed implant‐supported rehabilitation with distal cantilever resulted in a reliable treatment modality over the 5‐year observation period. Although biological parameters of MPI, SBI, keratinized tissue and peri‐implant mucosal levels showed statistically significant differences over time, the mean values for each patient remained within the normal limits of oral health. Complications were categorized as biological or technical. The majority of complications were technical complications (54/79) and of these most involved fracture of the acrylic teeth and base (20/54). While the survival rate was 100% for implants and 95.5% for prostheses, the application of strict criteria for treatment success resulted in an overall treatment success rate of 86.7%.     

Evaluation of mandibular posterior single implants with two different surfaces: a 5-year comparative study

BACKGROUND: Anatomic and biomechanical limitations can jeopardize successful single implantation in the mandibular posterior area. To overcome the limitations, the design and the surface of the fixtures were modified. This study evaluated the cumulative survival rate (CSR) of mandibular molars replaced with a sand-blasted, large-grit, acid-etched (SLA) single implant or an anodized (ANO) single implant and examined associated factors, such as the surface treatment, position, and length and diameter of the implants. METHODS: One hundred ninety-three single implants restored with an SLA implant and 112 single implants restored with an ANO implant in the mandibular molar area were selected from subjects who had visited the Department of Periodontology, Dental Hospital of Yonsei University, from March 2001 through June 2006. In the SLA group, 123 and 70 implants were placed in the first and second molar area, respectively. In the ANO group, 55 and 57 implants were placed in the first and second molar area, respectively. The 1- to 6-year CSR of the SLA and ANO groups was calculated using the life-table analysis. In addition, associated factors, such as the surface treatment, position, and length and diameter of the implants, were compared and analyzed using the chi(2) test (P <0.05). RESULTS: Two of 193 implants in the SLA group failed, giving a CSR of 98.96%; four of 112 ANO implants failed, giving a CSR of 96.43%. There were no significant differences with regard to the surface treatment, position, and length and diameter of the implants. CONCLUSIONS: Despite the anatomic and biomechanical limitation in the mandibular posterior area, mandibular posterior single implants showed a high CSR during the observation period. Mandibular posterior single implants can be an effective and reliable treatment modality that is not affected by the surface treatment, position, or length and diameter of the implant.     

Immediate loading: a simple protocol to create a passively fitting provisional fixed implant-supported complete denture in 1 day

Many studies have shown success with immediate loading of dental implants. The purpose of this paper is to report on a procedure that places implants with a sand-blasted and acid-etched surface and loads them with a fixed, provisional, immediately loaded mandibular complete denture, all in a single day. The various surgical, prosthetic, and laboratory phases are explained, with particular attention paid to a luting technique that is able to reduce prosthetic misfit. A series of 14 patients was treated with this protocol and followed for a mean of 28.2 months. A 100% implant survival rate was achieved, and all prostheses were in place and functioning at the most recent follow-up.     

Long-term survival and success of oral implants in the treatment of full and partial arches: a 7-year prospective study with the ITI dental implant system

PURPOSE: This study evaluated the long-term survival and success of different implant-supported prostheses supported by ITI implants. MATERIALS AND METHODS: Two hundred fifty consecutive patients were rehabilitated using implant-supported prostheses. Seven hundred fifty-nine implants were loaded. Single-tooth prostheses (n = 106), cantilever fixed partial prostheses (n = 42), fixed partial prostheses (n = 137), fixed complete prostheses (n = 5), implant/tooth-supported prostheses (n = 13), and overdentures (n = 37) were used. The mean follow-up period was 3.85 years. Life table analyses were performed. Implant survival rates were calculated by means of standard life table principles. Statistical analysis was performed to compare the implant survival and success by implant placement site for each type of prosthesis. RESULTS: The cumulative implant survival rates were calculated for implants supporting single-tooth prostheses (95.6%), cantilever fixed partial prostheses (94.4%), fixed partial prostheses (96.1%), fixed complete prostheses (100%), implant/tooth-connected prostheses (90.6%), and overdentures (95.7%). Similar survival and success rates were documented for implants placed in maxillae and mandibles. Implant size did not influence survival. DISCUSSION: Seven-year survival rates were similar for implants supporting single-tooth prostheses, cantilever fixed partial prostheses, fixed partial prostheses, and implant/tooth-supported prostheses. Medium-long term implant survival and success were not influenced by the site (maxilla or mandible). Implant and prosthetic survival rates for overdentures supported by 2 implants were comparable to those for overdentures supported by 3 or more implants. CONCLUSION: Prostheses supported by ITI implants represent a reliable medium-term treatment. (More than 50 references.)     

Dental implants in geriatric patients: a retrospective study of 47 cases

PURPOSE: To determine the overall success of dental implants placed in geriatric patients. PATIENTS: Dental implants were placed in 47 geriatric patients who were 79 or more years of age at the time of the procedure. The study group was composed of 27 men and 20 women, with a median age of 89 years and a range of 79 to 99 years of age at the time of implant surgery. A total of 73 dental implants were placed in the maxilla and 87 dental implants placed in the mandible. All implants were restored with fixed implant-supported prostheses or removable implant-supported prostheses. Eleven of the patients underwent maxillary sinus augmentation with porous hydroxyapatite and platelet-rich plasma. Seven patients had their implants immediately loaded. RESULTS: A total of 160 dental implants were placed in the 47 geriatric patients. One hundred fifty-nine integrated successfully. In the case of the failed implant, the site was grafted and another implant was placed 5 months subsequent to the initial failure. This replacement implant integrated and has been in function for 6 months. The survival rate for dental implants placed in the maxilla was 99% and in the mandible was 100% in our geriatric population. CONCLUSION: Treatment with dental implants can be predictable and safe for the rapidly growing geriatric population. Geriatric patients who are medically stable are suitable candidates for osseointegrated implant surgery, which facilitates oral function, comfort, and quality of life. A review of the 47 geriatric patients treated supports the conclusion that dental implants can be successfully placed and restored with fixed implant-supported or removable implant-supported prostheses.     

Are Short Dental Implants (<10 mm) Effective? A Meta‐Analysis on Prospective Clinical Trials

Background: This study aims to compare the survival rate of short (<10 mm) and standard (≥10 mm) rough‐surface dental implants under functional loading. Methods: An electronic literature search using PubMed and Medline databases was conducted. Prospective clinical human trials, published in English from January 1997 to July 2011, that examined dental implants of <10 mm with a 12‐month follow‐up were included in this meta‐analysis. The following data were retrieved from the included articles: the number of implants, implant dimensions, implant locations, types of prostheses, follow‐up periods, and implant survival rates. Kaplan‐Meier survival estimates and the hazard rates were analyzed and compared between short and standard implants. Results: Thirteen studies were selected, examining 1,955 dental implants, of which 914 were short implants. Short dental implants had an estimated survival rate of 88.1% at 168 months, when standard dental implants had a similar estimated survival rate of 86.7% (P = 0.254). The peak failure rate of short dental implants was found to occur between 4 and 6 years of function. This occurred at an earlier time point compared with standard dental implants, where the peak failure rate occurred between 6 and 8 years of function. Conclusions: This study shows that in the long term, implants of <10 mm are as predictable as longer implants. However, they fail at an earlier stage compared with standard implants.     

Implant prosthodontic rehabilitation of fibula free-flap reconstructed mandibles: a Memorial Sloan-Kettering Cancer Center review of prognostic factors and implant outcomes

PURPOSE: This study aimed to estimate the cumulative survival rates (CSRs) of implants placed in reconstructed mandibles and to identify prognostic factors that may influence implant survival. MATERIALS AND METHODS: The charts of 24 patients (10 male, 14 female) who had undergone mandibular resection and reconstruction with fibula free-flaps treated with implant-supported prostheses from April 1986 through December 2001 were reviewed. Information on demographics, surgical characteristics, treatment modalities, dentition, implant parameters, prostheses, and hyperbaric oxygen therapy (HBO) was gathered. Kaplan-Meier survival estimates were generated for the 100 implants that satisfied the inclusion criteria. Multivariate Cox proportional hazards regression models accounting for correlated implants within subjects were developed to identify prognostic factors for implant survival. RESULTS: Ninteen implants had been placed in native mandible (3 in irradiated bone) and 81 in fibula bone flap. Six implants failed during the follow-up period (mean 51.7 months). The overall 5- and 10-year CSRs were 97.0% and 79.9%, respectively. In the univariate analysis, variables associated with implant survival were age, gender, chemotherapy, radiation therapy, HBO, irradiated bone, implant diameter, xerostomia, trismus, opposing dentition, and type of prosthesis. At 5 years, the CSR of implants in patients with HBO was 86.7%; HBO was statistically associated with an increased risk for implant failure (P = .005, hazard ratio = 19.79, 95% CI: 2.42 to 161.71). DISCUSSION: The CSR was lower when implants were placed in a previously irradiated mandible. There is still a lack of reliable clinical evidence to support the effectiveness of HBO in these patients. CONCLUSIONS: A high survival rate was demonstrated for implants placed in fibula free-flap reconstructed mandibles. The finding that HBO was a risk factor can probably be attributed to the small sample size; further study is needed in this patient population.     

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.