Search

Objective The aim of this study was to estimate the effects of zirconia implants and recombinant human bone morphogenetic protein-2 (rh BMP-2) gel on the acceleration of local bone formation and osseointegration in the canine mandible. Materials and Methods Four groups of 48 implants with identical geometry were installed in the mandibles of beagle dogs: alumina-blasted zirconia implants applied with rh BMP-2, alumina-blasted zirconia implants applied with demineralized bone matrix ( DBM), alumina-blasted zirconia implants, and resorbable blast media-treated titanium ( Ti) implants. For the first two groups, zirconia implants were inserted after the surgical sites were filled with rh BMP-2 or DBM gel. For the other two groups, zirconia or Ti implants were installed with no adjunctive treatment. Fluorescent bone markers were administered to monitor bone remodeling at weeks 2, 4, and 5 postimplantation. After healing periods of 3 weeks and 6 weeks, the animals were sacrificed, and fluorescent microscopy, histology, and histomorphometric analyses were performed. Results Fluorescent microscopy showed that bone formation around the zirconia implants installed with rh BMP-2 gel was the most prominent at 2 weeks postimplantation, while the Ti implants acquired bone apposition mainly at week 5. No significant differences were found in bone area among the groups ( P > 0.05). The zirconia implants showed similar bone-to-implant contact to the Ti implants. There were no significant differences in bone-to-implant contact between the zirconia implants with rh BMP-2 gel and those with DBM ( P > 0.05). Conclusions The zirconia implants with alumina-blasted surfaces may achieve osseointegration in much the same manner as the well-established Ti implants. The area influenced by rh BMP-2 gel, including the alveolar crest, may cause active remodeling and early bone formation. [ABSTRACT FROM AUTHOR]

Objectives The aim of this prospective cohort study was to compute the long-term clinical survival and complication rates of alumina-toughened zirconia abutments used for implant-supported restorations and to evaluate the effects of several clinical variables on these rates. Material and methods From May 1998 to September 2010, 213 patients aged 18 years or older were recruited. The patients received 611 external hex implants and 328 implant-supported fixed restorations using alumina-toughened zirconia abutments. During the follow-up, each restoration was coded as a dental event, which included loosening or fracture of abutment screws, and abutment fracture. From the coded data, the effects of the investigated clinical variables-restored area (anterior/posterior), number of prosthodontic units (one/two units or over), prosthesis type (single-unit/multiunit without pontic/multiunit with pontic), implant system, and patient gender-on the survival of the abutments were evaluated. Survival analysis using Kaplan- Meier method and Cox proportional hazard model was applied. The 5-year survival and complication rates of the abutments were assessed. Results The number of prosthodontic units and the type of prosthesis had a significant association with complication rates ( P < 0.05). Kaplan- Meier survival analysis estimated that the cumulative 5-year complication rate of the abutments used in single restorations was 19.7%. Multiunit-fixed dental prostheses without and with pontics had complication rates of 3.9% and 3.8%, respectively. The 5-year survival rate of the abutments was more than 95%, regardless of the type of prosthesis. Conclusions Alumina-toughened zirconia abutments are likely to exhibit excellent long-term survival in clinical use for fixed restorations. Single tooth replacement with the abutment at the molar region may require special care and extra attention. [ABSTRACT FROM AUTHOR]