vendex and Maxillary-Diseases

Bone grafts are frequently used to enable the placement of dental implants in atrophied jaws. The biomechanical properties of bone grafts used in one- or two-stage implant procedures (in comparison with the use of nongrafted bone) are not well known.. The purpose of this study was (1) to measure cutting torques during the placement of self-tapping dental implants in nongrafted bone and in bone grafts, either as blocks or in a milled particulate form, in patients undergoing implant treatment in an edentulous maxilla and (2) to identify implants with reduced initial stability and to correlate these findings with a clinical classification of jawbone quality.. The study included 40 consecutive patients with edentulous maxillas, 27 of whom were subjected to bone grafting prior to or in conjunction with implant placement (grafting group) and 13 of whom received implants without grafting (nongrafted group). Grafted bone from the iliac crest bone was used (1) as onlay blocks, (2) as maxillary sinus inlay blocks, or (3) in particulate form in the maxillary sinus. Implants were placed after 6 to 7 months of healing, except in the maxillary sinus inlay blocks, where implants were placed simultaneously. Cutting torque values were obtained from 113 grafted implant sites and from 109 nongrafted implant sites.. Significantly lower cutting torque values were assessed in grafted regions than in nongrafted regions, irrespective of grafting technique. Lower values were also seen for implants placed in block grafts after 6 months when compared to other grafting techniques used. The cutting torque values revealed an inverse linear relation to the Lekholm and Zarb bone quality index.. The cutting torque values correlated well with the Lekholm and Zarb index of bone quality. Significantly lower cutting torque values were seen in grafted bone than in nongrafted bone.

Topics: Alveolar Bone Loss; Alveolar Ridge Augmentation; Biomechanical Phenomena; Bone Density; Bone Transplantation; Dental Implantation, Endosseous; Dental Implants; Dental Prosthesis Retention; Dental Restoration Failure; Follow-Up Studies; Hardness Tests; Humans; Jaw, Edentulous; Maxilla; Maxillary Diseases; Predictive Value of Tests; Stress, Mechanical; Torque; Wound Healing

In a previous study (Haas et al. 1995), we reported on preliminary results of 76 Brånemark implants placed in 71 patients with single-tooth gaps. The present study examines the results of the same group over a longer period of time: 55 implants were followed for more than 5 years, 12 for a period between 4 and 5 years and 1 implant for 46 months. One patient died 3 years after implant placement. Five patients lost their implant within 24 months after insertion. The drop-out rate was 2 implants in 2 patients. The recall rate was thus 97%. Of the 5 implant failures, 2 were located in the maxilla and 3 in the mandible. The Kaplan-Meier survival probability was 93% after 120 months. 74% of the sites showed healthy peri-implant soft tissue conditions. At 15 implants (22%) a bone resorption of more than 2 mm was observed on intraoral radiographs. The mean bone resorption was 1.8 mm in the maxilla and 1.3 mm in the mandible and did not increase with time (Pearson correlation coefficient: r = -0.06, P = 0.59). Abutment loosening occurred in 7 implants (10%), however all abutments that were fixed with a defined torque subsequently remained stable. Thus the favourable preliminary results could be maintained over an average 66 months, indicating that if implant loss happens it seems to occur during the first 2 years after insertion.

Topics: Adult; Aged; Austria; Bone Resorption; Dental Abutments; Dental Implants, Single-Tooth; Dental Prosthesis Design; Dental Prosthesis Retention; Dental Restoration Failure; Female; Follow-Up Studies; Humans; Life Tables; Longitudinal Studies; Male; Mandible; Mandibular Diseases; Maxilla; Maxillary Diseases; Middle Aged; Patient Dropouts; Periodontal Index; Probability; Statistics as Topic; Survival Analysis; Torque