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The present study evaluated implant survival and marginal bone loss in maxillae over a 15-year follow-up period as a function of either monocortical or bicortical implant anchorage. Of 207 standard Brånemark implants (10 mm in length) followed, 110 implants were judged to be monocortically anchored and 97 as bicortically anchored. The bicortically anchored implants failed nearly 4 times more often than the monocortical ones. Implant fractures accounted for over 80% of the observed failures and were found to affect the bicortical group almost 3 times more often. As tentative explanations, induction of increased stress and bending forces resulting from possible prosthetic misfit, presence of unfavorable arch relationships, or high occlusal tables in combination with bicortically anchored implants have been suggested, all indicating an overambitious fixation of the bicortical anchorage. Total marginal bone loss was low over the 15-year period and close to identical for the 2 groups, suggesting that the mode of cortical anchorage did not have any clinically significant influence on marginal bone remodeling. [ABSTRACT FROM AUTHOR]

Sixty-seven patients ranging in age from 16 to 86 years were included in this 3- to 5-year retrospective report focusing on implant survival and marginal bone remodeling in relation to implant diameter. A total of 299 Brånemark implants (3.75-mm diameter: 141; 4.0-mm diameter: 61; 5.0-mm diameter: 97) were placed in 16 completely and 51 partially edentulous arches. Seven of the 141 implants in the 3.75-mm-diameter group failed (5%). The corresponding value for the 4.0-mm-wide implants was 2 of 61 (3%). The highest failure rate, 18% (17/97), was seen for the 5.0-mm-diameter implants. The least favorable cumulative survival rates were seen in mandibles after 5 years and involving 4.0-mm- and 5.0-mm- diameter implants (84.8% and 73.0%, respectively). The marginal bone loss was generally low over the 5-year period. When the data were evaluated by the Cox regression analysis, a relationship was found between implant failure and implant diameter (P < .05), with a higher failure rate for the 5.0-mm-diameter implant. However, no relationship could be seen between implant failure and jaw type, or bone quality and quantity (P > .05). Neither was any relationship seen between marginal bone loss and bone quality and quantity, implant diameter, or jaw type when tested by multiple linear regression analysis (P > .05). A learning curve, poor bone quality, and changed implant design were suggested as possible reasons for the less positive outcome seen for the 5.0-mm-diameter implant. The fact that this implant was often used as a rescue implant when the standard ones were not considered suitable or did not reach initial stability was another plausible explanation. [ABSTRACT FROM AUTHOR]

A proposed protocol and differentiated success criteria for long-term evaluation of oral implants are presented. The protocol and criteria were applied to a retrospective patient material treated during a 1-year period and followed for 5 years. The protocol comprised a two-stage analysis of the collected clinical data. First, a quantitative analysis of the outcome was made using a life table. Based on the information obtained during the follow-up, each implant was categorized into one of three groups: unaccounted for, failure, or survival. A qualitative analysis of the survival group was then performed by active testing against defined criteria. Depending on the modes of clinical and radiographic examinations and their results, surviving implants were either further assigned to one of three success grades or remained in the survival group. The data are presented in a four-field table at one level of success. Strict success criteria together with individual stability testing and radiographic examination of each consecutive implant should be used when a new implant system is evaluated or when a new application is explored. Radiography alone and more moderate success criteria may be used to document routine treatments, provided that an already well-documented implant system is studied. [ABSTRACT FROM AUTHOR]

The positive predictive value of radiographic identification of unstable Brånemark implants was evaluated. Based on approximately 2,000 patients with implants followed during a 3-year period, a total of 84 patients were radiographically detected to have suspected failing implants. A total of 481 implants had been placed in these patients, but because of the study design and some patient dropouts, the evaluation was carried out in only 79 of the identified patients, who had 413 implants. Calculations were performed based on the number of occasions the implants were examined (n = 482) because some patients were assessed on more than one occasion. Results indicated a high positive predictive value (83%) to radiographically identify failing implants, and only 5% were clinically found to be failing without having been detected radiographically. In nine jaws (11%), the fixed prosthetic restorations were unnecessarily detached because of inaccurate radiographic diagnosis. The study indicated that radiographic identification of unstable implants is reliable when performed as part of annual examinations and when examining patients on a long-term routine basis. The timing for these assessments should be annual during the first 3 years of follow up for the unexperienced clinician and may thereafter be individualized with more clinical experience. [ABSTRACT FROM AUTHOR]

Image quality in preimplant computerized tomography (CT) examinations made with different radiation doses (40 to 280 mAs) and scanning modes (standard and helical axial, 15-degree angled, and frontal) and in conventional spiral tomography (Scanora) was compared. Mandibular canal and alveolar bone crest visibility was evaluated in images from mandibular jaw segments. Visibility was unaffected by radiation dose in CT examinations except in frontal scanning, where a small actual difference was statistically significant. Differences among CT scanning modes and between CT and conventional spiral tomography were highly significant. Low-dose mandibular preimplant tomography can be performed with CT using lower-than-normal radiation doses or with conventional spiral tomography. [ABSTRACT FROM AUTHOR]

A new self-tapping Brånemark implant designed for denser bone qualities was evaluated with regard to insertion technique, complications, marginal bone remodeling, and survival rate. Thirty patients, representing 21 mandibles and 9 maxillae, participated in the study. In each patient both standard and self-tapping implants were placed, and a total of 179 implants, 88 self-tapping and 91 standard, were inserted. Thirteen of 62 mandibular self-tapping implants reached their correct positions only after using the screw tap or the cylinder wrench for manual insertion. No such problems were noted when using standard fixtures after bone pre-tapping. In the maxillae, neither of the two implant designs presented any problems. One standard and one self-tapping fixture failed to osseointegrate. Radiolucencies were seen in the bone around the apical portion of two fixtures, one of each design. The mean marginal bone resorption after 1 year of follow-up was 0.5 to 0.6 mm for the two fixture types. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]