The International Journal of Oral & Maxillofacial Implants, 05/2000

The purpose of the present study was to compare the success of and surgical differences between 1- and 2-stage sinus inlay bone grafts and implants after 1 year in function. The individual risk for implant failure in grafted areas among 1-stage patients was about twice the risk in 2-stage patients (odds ratio 2.3, CI 0.6; 8.5). The risk for implant failure in non-grafted areas was significantly lower (P .05) than in grafted areas, regardless of the technique used. Forty edentulous patients, selected according to strict inclusion criteria from consecutive referrals, were allocated to one or other of the 2 sinus-inlay procedures. Twenty patients received bone blocks fixed by implants to the residual alveolar crest in a 1-stage procedure (group 1). In another 20 patients, particulated bone was condensed against the antral floor and left to heal for 6 months before implants were placed (group 2). An almost equal number of implants was placed in the patients of each group, 76 in the 1-stage procedure and 74 in the 2-stage procedure. Additionally, 72 and 66 implants were placed in the anterior non-grafted regions of group 1 and group 2 patients, respectively. After 1 year in function, a total of 20 implants failed in 1-stage patients, versus 11 in 2-stage patients. Sixteen and 8 implants, respectively, of these were placed in grafted bone. All but one 1-stage patient received the planned fixed prosthetic restorations, but 1 restoration was redesigned after the first year in function because of a functionally unacceptable prosthetic design. At the 1-year follow-up, one 2-stage patient lost her prosthesis as the result of multiple implant failures. Bruxism and postoperative infections were the only parameters that could be related to implant failure, however, depending on the statistical method used. Keywords: bone transplantation, dental implants, endosseous dental implantation, maxillary sinus

A total of 114 ITI solid-screw implants was consecutively placed in 55 partially edentulous patients and restored with 68 fixed prostheses. The patients were followed for at least 5 years in a prospective study that focused on implant success and longitudinal reactions of the peri-implant hard and soft tissues. During the study period, 5 implants failed and 15 implants were lost to follow-up, resulting in a cumulative survival rate of 95.3% after 5 years of loading. The success analysis included additional strictly defined events (first occurrence of marginal bone loss > 4 mm, first occurrence of pocket depth > 4 mm, and first occurrence of crevicular fluid volume > 2.5 mm) and resulted in a cumulative 5-year success rate of 89.0%. Median loss of marginal bone, as observed on radiographs, was 0.7 mm between implant placement and prosthetic treatment and 0.5 mm between prosthesis placement and the 5-year evaluation. Compared to the previous years value, the annual increase in marginal bone loss did not reach a level of statistical significance between 1 and 5 years of function, so that a steady state prevailed. The incidence of lingual-palatal surfaces affected with remarkable plaque deposits increased from 13% after prosthesis placement to 23% after 5 years. Sulcus Bleeding Index, probing depth, attachment level, and crevicular fluid volume were used to describe the health of the peri-implant soft tissues. The research parameters remained almost unchanged and indicated a soft tissue response within physiologic levels. Most mechanical complications were experienced during the first year of loading and were related to loosening of occlusal screws, which occurred in 8 (12%) of 68 restorations. Keywords: bone resorption, dental implants, endosseous dental implantation, oral mucosa, partially edentulous jaw

Originally, osseointegrated implants were used principally in the anterior region of the mandible and maxilla, but use in the posterior segments of both arches is common today. The long-term success of implants placed in the posterior region, an environment of stronger forces and poorer bone quality, has not been thoroughly reviewed. The purpose of the present study was to review a large series of Brånemark System implants placed in posterior maxillae (660 implants in 202 patients) that have been restored with fixed partial ceramometal restorations and followed for as long as 12 years after loading. Thirteen of the implants (2%) failed betiacement and loading, 12 implants were lost between loading and the end of the first year, and 10 failed thereafter, 2 as the result of fractures at 3 and 4 years. The cumulative success rate is therefore 94.4% at 5 to 6 years and 93.4% after 10 years. The quality and quantity of bone appeared to have little influence on the success rate. Surgical techniques are particularly important to the success of osseointegrated implants placed in the posterior maxilla. With careful surgical planning and execution, a success rate of approximately 95% at 5 years can be achieved. Keywords: dental implants, posterior maxilla, osseointegration

It is often assumed that there is a direct relationship between the bone density adjacent to an implant, as revealed by radiographs, and the percent histologic osseointegration. Moreover, the lack of standardized methods for evaluation of histologic preparations makes it difficult to compare published studies, especially as little is known about the variables that influence these measurements. In this animal study, computer-assisted lineal analysis was used to evaluate the effects of subject, tooth position, and implant surface site on measured bone density and osseointegration in a bone augmentation experiment. Three sites--coronal lingual, apical lingual, and apical facial--were analyzed around each of 6 (3.75 x 8 mm) threaded machined titanium implants, as well as the apical facial site of 21 other implants placed in the mandibular premolar area of 5 dogs. In all sites, a progressive decrease in bone density was observed from bone adjacent to the implant to that at the titanium implant surface. There was an animal effect on osseointegration, but there were no differences between the mandibular premolar locations (second, third, and fourth). Most importantly, there were significant measurable effects attributable to the surface site examined. The need for carefully standardized histologic evaluations is established. Keywords: bone density, endosseous dental implants, histology, histomorphometry, osseointegration

Osseointegrated threaded titanium screw-type implants rarely lose integration after the first year of clinical function. Implant failure can occur for other reasons, with implant fracture being one of the major reasons for late failure. The purpose of the present study was to determine the incidence of implant fracture in completely edentulous and partially edentulous arches and to determine what factors may predispose an implant to a higher fracture risk. A retrospective evaluation of 4,937 implants was performed to determine the incidence of and factors common to fractured implants from a sample of implants placed and restored in one institutional setting. Based on the results of this study, the following observations were made: implants fracture at similar rates in the maxilla as in the mandible (0.6%), implant fractures occur more frequently in partially edentulous restorations (1.5%) than in restorations of completely edentulous arches (0.2%), all observed fractures occurred with commercially pure 3.75-mm-diameter threaded implants, and prosthetic or abutment screw loosening preceded implant fracture for the majority of the implants. More studies would be helpful to further explore the relationship and progression of factors associated with implant fracture. Keywords: endosseous dental implantation, implant maintenance, osseointegration, retrospective studies

This study presents a histomorphometric and biomechanical comparison of bone response to commercially pure titanium screws with 4 different types of surface topographies placed in the tibial metaphysis of 12 rabbits. Each rabbit had 4 implants placed, 2 in each tibia. The 4 surface topographies were a machined surface, a grit-blasted surface, a plasma-sprayed surface, and an acid-etched (Osseotite) surface. After a healing period of 5 weeks, histomorphometric and removal torque data revealed a significantly higher percentage of bone-to-implant contact and removal torque for acid-etched implants compared to machined, blasted, and plasma-sprayed implants. Within the limits of this short-term experimental study, the results indicated that micro-rough titanium surfaces obtained with acid-etching procedures achieved a 33% greater bone-to-implant contact over machined titanium surfaces with an abutment-type roughness and provided enhanced mechanical interlocking. Keywords: dental acid etching, endosseous dental implants, histomorphometry, surface properties, titanium

The aim of this article was to review the literature on materials, designs, and surface topographies of endosseous dental implants. The different categories of dental implants and the parameters of their design were analyzed in relation to their effect and significance in the process of osseointegration. The events that immediately follow implantation were described, emphasizing the factors that play a role in the development of the bone-implant interface. In addition, the methods and techniques that allow qualitative and quantitative evaluation of the interfacial zone were reviewed and their clinical correlation was assessed. Keywords: dental implants, dental materials, histomorphometry, laboratory techniques and procedures, osseointegration, surface properties

The aim of this multicenter study was to evaluate cumulative success and survival rates of ITI implants after 7 years. A complete medical report was obtained for all 440 patients enrolled in this investigation, which involved 10 different private practices. The 1,022 consecutively placed implants were distributed between completely edentulous, partially edentulous, and single-tooth replacement cases. During the annual follow-up visit, each implant was examined both clinically and radiographically using predefined success criteria. The cumulative survival and success rates were calculated for all implants. Implant subgroups were defined according to the medical history of the patients or pooled according to various indications, locations, implant designs, or implant lengths. In each subgroup, the related cumulative success rate was statistically compared to the global cumulative success rate. Fifteen implants (1.4%) were regarded as early failures, and at the end of the follow-up, the global failure rate reached 6.6%; 30 implants (3%) were lost to follow-up. At 5 years, the cumulative survival rate was 95.4%; this declined to 92.2% at 7 years. The weakest success rates were observed for implants placed in older patients, periodontally treated patients, and completely edentulous arches. Conversely, cumulative success rates that were significantly above average were observed for patients between 40 and 60 years old without pathology, implants placed after bone regeneration, solid-screw implants, implants placed in edentulous spaces, and implants placed as single-tooth replacements. This investigation has demonstrated that in these 10 private practice settings, the success rate for ITI implants remained high for up to 5 years and declined slightly between 5 and 7 years. It should be noted that in later year intervals, a relatively small number of implants remained for the analysis of cumulative success rates. Keywords: dental implants, longitudinal studies, life tables

Alveolar ridge distraction is a recent and promising technique for ridge augmentation. Since 1997, a new distraction system incorporating a distraction implant has been in use. It can be used for alveolar ridge distraction and is not removed from the alveolar ridge. Upon completion of the distraction, it remains in the alveolar process for later prosthetic treatment. Thirty-five patients were treated with distraction implants for the correction of alveolar ridge deficiency. In 10 patients with atrophy of the mandible or maxilla, 16 patients with severe defects of the alveolar process after trauma, and 9 patients with localized alveolar ridge defects after single tooth loss, alveolar ridge distraction was carried out with the aid of 62 distraction implants. The distraction implants were loaded by prosthetic superstructures 4 to 6 months after distraction. A clinical and radiologic follow-up was carried out. Periotest values were examined, and peri-implant bleeding and probing depth were registered prior to prosthetic treatment and 3, 6, and 9 months after implant loading. In 29 patients, distraction was carried out without complications or problems. Two distraction implants were lost. In 2 patients distraction was discontinued because of ankylosis of the distraction segment. In 1 patient the alveolar ridge was overcorrected, and another patient experienced a persisting hypoesthesia of the lip. For 5% of the implants, pathologic probing depth of more than 3 mm and sulcus bleeding were registered prior to prosthetic treatment. These observations decreased during the next 9 months. Periotest values were normal before the start of prosthetic treatment. There was a decrease in the Periotest values, thus an increase in implant stability, during the following 9 months. It was concluded that alveolar ridge distraction using distraction implants can be a successful technique for alveolar ridge augmentation with a low rate of complication. Acceptable esthetic and functional results can be achieved by this atraumatic technique of surgery and distraction. Keywords: alveolar ridge augmentation, dental implants, distraction osteogenesis

Many clinicians have reported on the success of immediately loaded implants supporting a bilaterally stabilized provisional fixed prosthesis. This protocol offers several advantages, including increased masticatory function, minimized uncontrolled transmucosal loading through cross-arch stabilization, improvement of psychologic well-being, and reduction in treatment time. However, the development and maintenance of proper dentogingival esthetics in the edentulous maxilla presents substantial challenges for the implant team. This article presents the specific pretreatment diagnostic requirements for immediate loading of single-stage implants and demonstrates a new surgical technique, followed by appropriate prosthodontic management, to develop an optimal gingival profile with interdental papillae surrounding a natural-looking dentition. One hundred fifty-one ITI implants were placed into 22 dental arches and immediately loaded with a 1-piece fixed prosthesis. The results of this technique over the last 5 years are presented. Keywords: dental implants, endosseous dental implantation, gingival papilla, implant-supported dental prosthesis, osseointegration, surgical flaps

The purpose of this investigation was to modify the method for implant placement in the posterior parts of the arches for fixed implant-supported prostheses using minimally invasive surgery. Eighty-six implants were placed posterior to the mental foramina in patients with severely resorbed mandibles, and 75 implants were placed in the posterior severely resorbed maxilla. Bone grafting from the mandible to the maxillary sinus was performed in 9 patients with severely atrophic maxillae. In all patients, optimal use of the anatomic features of the arch was achieved by tilting the implants. Patients were followed up for 12 to 123 months after prosthesis connection (mean 18 months). Three maxillary implants were lost at the time of abutment connection: 1 in the pterygoid plate, 1 close to the posterior sinus wall, and 1 placed in the palatal cortex. One implant was mobile approximately 1 year later, apparently because of an ill-fitting prosthesis. In the mandible, no implants were lost. The method described for the treatment of edentulous arches represents an alternative therapy to several others currently in use. This minimally invasive surgical procedure should be applicable in an outpatient clinic for treatment of severely resorbed posterior portions of the arches with implant-supported prostheses. Keywords: bite force, bone graft, dental cantilever bridge, dental prosthesis, endosseous dental implantation, endosseous dental implants, maxillary sinus, mandibular nerve, partially edentulous jaw

To date, distraction osteogenesis has been carried out exclusively with devices that allow distraction in one given direction only. However, the new distraction abutment system described in this article allows distraction in any functionally or esthetically desired direction following osseointegration of 1 or several implants, provided that there are adjacent teeth or other osseointegrated implants. With this abutment system, an implant fixed in a position dictated by available bone volume can be moved into a prosthetically desirable position following segmental osteotomy. Accordingly, it also allows correction of the position of implants that were placed at an early age but whose position has changed as the result of jaw growth. Compared with conventional augmentation techniques carried out before or after implant placement, this method should lead not only to a shorter overall treatment time, but also to reduced strain on the patient and better long-term prognosis for success of implants. Keywords: dental abutment, dental implant, distraction osteogenesis, segmental osteotomy