The International Journal of Oral & Maxillofacial Implants, 04/1989

Axially directed closing and chewing forces were measured in patients with mandibular fixture-supported cross-arch bilateral posterior two unit cantilever fixed prostheses occluding with maxillary complete dentures. Eight miniature strain-gauge transducers mounted in the maxillary denture enabled registration of local and total forces over the entire prosthetic restoration simultaneously. In asic occlusion, with simultaneous occlusal contacts on all occluding units, closing and chewing forces were distally increasing. Infraoccluding the first cantilever unit bilaterally approximately 100 µm resulted in decreased total closing and chewing forces over the cantilever segments, but did not influence the leverage at the cantilever joint distal to the distal retainers. Infraoccluding the second cantilever units approximately 100 µm caused a pronounced reduction of both the total closing and chewing forces over the entire prosthetic restoration as well as over the cantilever segments, and also resulted in a marked (50%) decrease in the leverage at the cantilever joints. Causes of the force and leverage reductions and some clinical considerations are discussed. Keywords: complete dentures, implant-supported prostheses, occlusal forces

The effect of local administration of epinephrine was tested in a rabbit experimental model. Identical commercially pure titanium implants were inserted in the right legs of New Zealand white rabbits after pretreatment with epinephrine; the left legs served as controls. This acute administration of epinephrine was shown to have no significant impact on the incorporation of the implant as measured after 7 weeks. Keywords: epinephrine, titanium implant

A stable and dimensionally accurate surgical template provides a precise and stable reference for implant placement in the partially edentulous patient. Implant location and axis can be rigidly! controlled with calibrated channels incorporated into the template. Keywords: axis control, calibrated channels, silicone mold

Site preparation for oral implants is a delicate surgical procedure. In the ITI F-type and Bonefit implant systems, two cylindrical burs are available. Experiments were performed to verify the clinical experience that the longer bur is more accurate in defining the direction of implants. Several preparations were made in six human femur heads. The purpose of the experiments was to investigate the difference in parallelism between preparations made with the standard cylindrical bur and the bur with the long shaft. The results showed that the bur with the longer shaft was preferred for obtaining an accurate direction and parallelism of the implants. Keywords: ITI implant, operation technique, parallelism, radiologic registration

Bone grafts from the hip in combination with Brånemark self-tapping fixtures have been used to rehabilitate patients with extremely resorbed maxillae. Experiences and results from the first ten consecutive cases have been analyzed to form the basis for further use of the method. Eight of 57 fixtures placed have been lost to date. Surgical complications, including exposure of the bone transplant, have occurred in three patients. The method should be used with caution, and cases should be meticulously chosen to exclude those who do not have proper motivation to endure the long-lasting and demanding surgical and prosthetic procedures required. The combined use of implants and transplants should not be used routinely until a long-term evaluation of the method and results has been made. Keywords: bone graft, implants, maxillae

The long-term success of an implant-supported prosthesis is dependent not only on osseointegration of the implant to the surrounding osseous structures, but also the integrity and health of the surrounding peri implant tissues. This paper defines and discusses the dental professional's role in (1) examining and assessing the peri-implant tissues (2) providing clinical maintenance protocols, and (3) recommending effective home-care instructions for a patient with implant-supported prostheses. Keywords: home care, implant maintenance, maintenance intervals, osseointegration, peri-implant tissues, periodontal parameters, tissue-integrated prostheses

The aim of this study was to assess bone response to a novel matched modulus material using more rigid titanium as a control. Implants subjected to different loading conditions were retrieved from rabbit tibiae after various time intervals, and new bone growth was assessed by histomorphometric methods. Block face microscopy was employed for histologic purposes. From a statistical analysis of the histomorphometric results, it could be concluded that titanium implants encouraged the greatest overall amount of bone formation around them when they were unloaded, when they were loaded immediately, and after a healing period. Keywords: bone, endosseous implant, histomorphometry, matched modulus, strain

Plaque formation was studied in vivo by setting different implant materials on gingiva. The number of adhering viable bacteria depended on material surface properties 4 hours after setting, but not 48 hours after setting. The formation of pellicle-like thin layers and subsequent covering by lamellarly formed plaque were observed on the surfaces of all materials. Streptococcus species were predominant at the 4-hour setting time and anaerobes increased at the 48-hour setting time; this was common to all materials. The results indicate that surface properties of the implants influence early bacterial adherence, but do not influence bacterial flora or plaque maturation. Keywords: implant materials, in vivo, plaque

Four mandibular specimens were radiographically examined bilaterally to locate the mandibular canal. The following radiographic techniques were used: periapical and panoramic radiography, hypocycloidal tomography, and computed tomography (CT). The distance; from the crest of the alveolar process to the superior border of the mandibular canal was measured in millimeters on all radiographs. The specimens were then sectioned, and the location of the mandibular canal (as measured on contact radiographs of the sections) was compared with measurements made on the other radiographs. The results showed that CT gave the most accurate position of the mandibular canal and is therefore probably the best method for preoperative planning of the implant surgery involving the area close to the mandibular canal. Keywords: computed tomography, implant surgery, inferior alveolar artery, inferior alveolar nerve, mandibular canal, radiography

The stress distribution generated in the surrounding jaw bone was calculated and compared for different types of dental implants (cylindrical, conical, stepped, screw-shaped, hollow cylindrical) by means of the finite-element method. Both a fixed bond and a pure contact without friction between implant and bone were considered as interface conditions. The results demonstrate that different implant shapes lead to significant variations in stress distributions in the bone. In particular, implant surfaces with very small radii of curvature (conical) or geometric discontinuities (stepped) imply distinctly higher stresses than smoother shapes (cylindrical, screw-shaped). Moreover, a fixed bond between implant and bone in the medullary region (as may be obtained with a bioactive coating) will be advantageous for the stress delivered to bone, since it produces a more uniform stress distribution than does a pure contact. Keywords: bone resorption, dental implants, finite-element method, stress distribution

Brånemark System implants were used for orthodontic anchorage to correct a cross-occlusion relationship between a mandibular canine and a maxillary lateral incisor. Keywords: implants, orthodontic anchorage, tooth repositioning