The International Journal of Oral & Maxillofacial Implants, 06/1993

This paper reviews the outcome of 2,194 Brånemark implants placed in 540 patients by one of the authors over a 6-year period. The overall failure rate of 5.92% is consistent with other studies; however, when patients were subdivided into smokers and nonsmokers, it was found that a significantly greater percentage of failures occurred in smokers (11.28%) than in nonsmokers (4.76%) (P .001). These differences were significant for all areas except the posterior mandible. While failure rates decreased with increasing implant length, failure rates for each implant length were consistently higher in smokers than in nonsmokers. The possible mechanisms of failure in smokers are discussed, and a protocol for cessation of smoking around the time of surgery is proposed. Keywords: Brånemark implants, failure, implant length, implant location, osseointegration, smoking/adverse effects

A total of 974 patients were treated with 2,023 IMZ implants. A variety of prosthodontic designs were utilized . These included replacement of single teeth, use as pier abutments, and for totally implant-supported prostheses. The implants were followed in function for 6 to 60 + months. Absolute success rates were 96. 4% and 98.4% in the maxilla and mandible, respectively. Cumulative success rates at the end of the study were 92.9% and 95.8% in the maxilla and mandible, respectively. The use of an intramobile element is also discussed. Keywords: edentulism, IMZ implants, prostheses, intramobile element

Thirteen commercially available oral implant systems were investigated with respect to design and surface topography. The implants were divided into four groups, depending on their different surface materials and treatments. Surface topography was measured with a measurement system for noncontact surface profilometry using confocal scanning microscopy. Results indicated that design, as well as surface topography, varied considerably between the different implant systems. Keywords: design, optical profilometry, oral implants, surface topography

Sixty-seven partially edentulous patients with Applegate-Kennedy Class I or II situations were consecutively treated with freestanding implant-supported prostheses and followed up for 5 years. A total of 70 jaws were provided with 94 prostheses supported by 259 implants. During the report period, seven patients were lost to follow-up. Seven implants were found to be loose and were subsequently removed, which did not influence prosthesis stability. Thus, the overall cumulative survival rate was 97.2% and 100% for implants and prostheses, respectively. On average, 0.8 mm of marginal bone was lost around implants in maxillae, as compared to 0.6 mm in mandibles. The major clinical problem was related to fatigue fractures of the resin veneer material. Loose gold alloy screws were also observed. Keywords: complications, follow-up, implants, osseointegration, partial edentulism

Numerous investigations give evidence of improvement of masticatory performance when edentulous patients have had implants placed. A comparative study was carried out to investigate the oral function and tactile sensibility of patients restored with implant-supported overdentures. Twenty-six patients with ITI implants and 18 patients with natural-tooth roots were selected. The minimal pressure threshold perceived in vertical and horizontal directions was registered with dynamometers. Maximal occlusal force was recorded with a miniature bite recorder placed between each pair of antagonistic teeth on both jaw sides separately. All measurements were repeated three times and the average was calculated. The records of minimal perceived pressure revealed a significantly higher threshold (factor 100) for the implant group. In both test groups, values registered in the vertical direction were slightly increased. A tendency for test subjects with implants to reach higher maximal occlusal force was observed, but not at a statistically significant level. In both test groups, the average maximum was found on the second premolar. The minimal pressure threshold seems to depend on the presence of receptors in the periodontal ligament. The records of maximal occlusal force, which were similar in both test groups, lead to the assumption that the limitation in maximal occlusal capacity of overdenture wearers is multifactorial and does not depend on the presence of a periodontal ligament. Keywords: copings, implants, occlusal force, overdentures, pressure threshold

The treatment design of most dental restorations is largely empirical and based on the experience of the individual practitioner. Because the biomechanical aspects of implant-supported restorations are difficult to assess on an individual basis, there is a possibility for compromised biomechanical performance of the implant-retained restoration to achieve satisfactory esthetics and phonetics. Through repeated loading cycles, the restoration or its components may fatigue and fail. This study evaluated the biomechanical behavior of the crown component relative to the gold retaining screw and abutment under load to provide insight into the mechanism of loosening and fracture of the retaining screw. A two-dimensional finite element model of the dental implant components was developed for nonlinear contact analysis. A simulation of tightening of the retaining screw was followed by axial loading of a cusp tip on the implant-supported crown. Loading of the cusp tip resulted in separation of the contact between (1) the gold retaining screw and abutment, and (2) the crown and the abutment. Repeated loading and unloading cycles resulted in alternating contact and separation between the retaining screw head base and the crown. Clinical findings of screw loosening and failure probably result from these separation events and from elevated strains in the screw as demonstrated by the model. Keywords: contact analysis, dental implant, finite element analysis, nonlinear, prosthodontics

This report presents a method for determining the optimum arrangement of implants and the optimum scheme of prosthesis splinting using biomechanics and three-dimensional finite element analysis. The three-dimensional finite element structural analysis method was used to determine the distribution of occlusal forces on teeth and dental implants. The results of the analysis showed that force distribution on occlusal surfaces does not change significantly with changes in the scheme of prosthesis splinting or implant positions. The induced stresses in bone are sensitive to the scheme of prosthesis splinting and implant positions. Induced stresses on implants for different schemes of prosthesis splinting and different implant positions varied as much as 1,000%. Therefore, the selection of implant positions and of the scheme of prosthesis splinting is critical for the longevity and stability of an implant prosthesis. Keywords: finite element analysis, prosthesis design

Trauma to branches of the mandibular nerve may occur during oral surgical procedures and result in varying degrees of altered sensation. Since mandibular implant surgery involves mucoperiosteal flap elevation and bone removal during site preparation, complications involving altered sensation are to be expected. This study replicated a retrospective questionnaire study carried out in Toronto, Canada, and showed that the prevalence of altered sensation in implant patients in Adelaide, Australia (36%) was consistent with that found in Toronto (37%). These data reflect the incidence of altered sensation reported for similar oral surgical procedures and suggest that further characterization of this complication following mandibular implant surgery is necessary. Keywords: altered sensation, anesthesia, dental implants, inferior alveolar nerve, lingual nerve, mandible, mental nerve, oral surgery, paresthesia

Changes in the bone mineral content (BMC) of edentulous mandibles after augmentation with porous hydroxyapatite (HA), in blocks (B) in one side and in granules (G) in the opposite side, were measured in vivo by dual-photon absorptiometry. The BMC changes in each side at the 1-, 2-, and 3-year follow-up were expressed in percent of the 1-week postoperative BMC value. In unexposed augmentations new bone formation seems to occur during the first year in the HA-B sides, followed by the biologic age-related BMC loss; while the HA-G sides show pronounced resorption of hydroxyapatite and bone during the entire period. Although porous HA-B and HA-G are unsuitable for residual ridge augmentation, porous HA-B may be used for implantation in areas without risk for exposure of HA resulting from loading of covering soft tissues. Keywords: bone changes, bone mineral content, dual-photon absorptiometry, hydroxyapatite, implants, mandible, residual ridge augmentation, surgery

Improvements in planning for the provision of silicone auricular prostheses have been achieved with CT scanning. The analysis of information using a computer workstation has enabled preoperative determination of skull thickness and position of implants in relation to the proposed location of the prosthesis. The technique is of particular value in cases of craniofacial microsomia. Keywords: auricular prosthesis (epithesis), CT scanning, endosseous skull implants

A cavity was prepared in a submerged and impacted maxillary canine in the location of a missing lateral incisor. An 8-mm-long Screw-Vent implant was threaded into the site to function as a dental pin via mechanical retention. A Swede-Vent implant was placed in the area of the adjacent central incisor. After a 6-month submerged healing period, the Swede-Vent implant had clinically osseointegrated, and no breakdown of the dental tissue around the Screw-Vent implant was observed. The implants were restored with a two-unit splinted fixed prosthesis. Keywords: dental pin, endosseous implants, root-form implants

This article describes a complication that occurred with root-form implants: an acute periodontal abscess associated with an implant during the maintenance phase. The clinical treatment is outlined, as are the results achieved. Keywords: antibiotics, debridement, diagnosis, guided tissue regeneration, immediate implant, periodontal abscess