The International Journal of Oral & Maxillofacial Implants, 03/1990

In a series of scanning electron microscopic studies, the reaction of osteogenic cells to hydroxylapatite (HA) implant materials was investigated in culture and following implantation. Tissue components as found in normal rat and dog bone were identified at the interface in both test systems. In vivo, implant bed cells showed an intimate contact with the HA surfaces. Osteoblasts deposited organic matrix and bone mineral in direct apposition to HA, with no evidence of encapsulation or granulation tissue. The development of such a direct spatial relationship appears to involve mechanisms more encompassing than epitaxis. Keywords: cell adhesion, ceramics, collagen, hydroxylapatite, implants, osteoblasts

This study compared the reparative processes around cylindrical glass ceramic-coated and pure titanium implants placed in feline femurs. Six weeks after implant placement, bone specimens with inserted implants were prepared for histologic examination including histomorphometric quantification of the relative implant surface areas that were in contact with bone. The glass-ceramic implants were surrounded by a 0.2- to 0.5-mm envelope of fibrous connective tissue. By contrast, the major part of the titanium implants (81% ± 5%) was in direct contact with living lamellar or woven bone. Thus, titanium and glass ceramic evoked different reparative processes when implanted in bone, and only the titanium implants appeared to become osseointegrated. Keywords: glass-ceramic implants, osseointegration, titanium implants

A surgical technique for rehabilitation of severely resorbed edentulous maxillae using fixed prostheses or overdentures supported by osseointegrated fixtures in immediate autogenous corticocancellous bone grafts from the ilium is described. The results of the first 23 consecutively treated patients are reviewed. The mean observation time was 4.2 years (range 1 to 10 years). A total of 124 fixtures was originally placed into the grafts, supplemented with 16 fixtures inserted later into seven of the jaws. Throughout their observation period, 17 of the patients had continuously stable prostheses. The remaining five had overdentures, and one patient had resorted to a conventional complete denture. After 4 years, 12 of 16 patients had continuously stable prostheses. Corresponding values at 5 years were 7 of 8 patients. Calculated from the date of abutment connection, 82. 1% and 81.6% of the original fixtures were clinically stable and radiographically osseointegrated after 4 and 5 years in function, respectively. From the date of fixture placement, the corresponding figures were 75.3% and 73.8%, respectively. The mean marginal bone loss after the first year of prothesis function was 1.49 mm. The annual marginal bone loss thereafter was about 0.1 mm. The results indicate that this technique is worthwhile for patients with extreme maxillary atrophy and who cannot wear conventional complete dentures. Keywords: alveolar process resorption, autogenous bone grafts, edentulism, osseointegrated fixtures

The microbiota associated with oral endosteal sapphire ceramic implants was studied using cultural methods. Samples were taken from both implant and control (tooth) sites, and comparisons were made between healthy and diseased and between implant and control sites. Diseased sites harbored a microbiota with a large number and proportion of Gram-negative anaerobic rods, black-pigmented Bacteroides, and surface translocating bacteria. Healthy sites in the same patients had smaller amounts of bacteria dominated by facultative Gram-positive cocci and rods. The microbiota in diseased and healthy implant and control sites was very similar. It is suggested that peri-implant tissues behave very similarly to periodontal tissues and that peri-implantitis lesions should be considered as site-specific infections harboring a high number of periodontal pathogens, mainly Gram-negative anaerobic rods. Keywords: dental implants, peri-implantitis, periodontal pathogens

After periods of observation from 3 to 36 months, biopsies were obtained from 22 patients in whom porous block and particulate hydroxylapatite ceramic (Interpore 200™)) had been used for augmentation procedures and in two patients in whom nonporous particulate hydroxylapatite (Calcitite ) had been used. Histologic examination of serial sections of decalcified specimens revealed vital bone formation in relation to the blocks, whereas the particulate was encapsulated in fibrous tissue. The differences in biological behavior are discussed. Keywords: biopsy, bone ingrowth, histology hydroxylapatite, porous ceramic, ridge augmentation

Electron spectroscopy and argon ion etching were used to determine the depth and composition of the oxide layers of six competitive dental implant systems. To minimize problems associated with analyzing the active oxide layers, the implants were removed from their original packaging in an oxygen-free environment. The majority of the six implant systems were found to have similar oxide thicknesses in the range of 20 to 34 Å. Some variation was found in the extent of non-oxide surface contamination. Keywords: dental implants, electron spectroscopy, oxide layer, titanium

Nine clinical centers using the Brånemark System participated in a prospective study of 159 partially edentulous patients between 18 and 70 years of age. Clinical parameters evaluated were plaque index, gingivitis, pocket depth, bleeding index, tooth mobility, and stomatognathic function. Initially, 558 fixtures were placed and 521 remained in the study following prosthesis placement (199 prostheses in 154 patients). Fixtures were lost or unaccounted for because of nonintegration prior to prosthesis fabrication (19), patient withdrawal (11), prosthodontic reasons (6), and failure during prosthetic procedures (1). Failure was primarily attributable to unfavorable bone quality, sex (more in males), and smaller fixture size. Complications and failure related to other patient characteristics are presented. After 1 year of a 5-year study, preliminary results suggest that a success rate equal to or better than that obtained with edentulous patients may be expected. Keywords: Brånemark System, oral implants, osseointegration, partial edentulism

The use of magnetic resonance imaging as an adjunctive aid to determine the amount of bone available and the anatomic limitations for the placement of endosseous dental implants is introduced. Advantages and disadvantages are discussed. The results suggest that magnetic resonance imaging can provide, without the need for a reformatting software program, adequate information concerning the amount of bone and anatomic limitations for placement of endosseous implants in the mandible and maxilla. Keywords: CT scan, endosseous dental implants, magnetic resonance imaging

The incorporation of more than one dental implant system within the same restorative segment may be a reliable approach to treatment. This article describes a clinical situation that was resolved, after the failure of a pre-existing subperiosteal implant, by the use of both subperiosteal and osseointegrated fixtures concurrently. The result was an increase in stability, and it is hoped that restoration settling will be minimized. Keywords: atrophic, endosseous implant, hydroxylapatite, subperiosteal implant

A technique that facilitates the removal of teeth or retained root fragments without traumatizing the alveolar bone of the socket is described. This technique may be employed whenever such extractions are envisaged, but it is particularly important when the subsequent placement of dental implants is planned. Keywords: extraction techniques, immediate and delayed implants, Periotome

The van Ooy lip and cheek retractor, a device that provides a wide and unobstructed view of the patient's oral cavity during implant surgical procedures, is introduced. Keywords: lip and cheek retractor, oral implants, visibility