Guided bone regeneration at zirconia and titanium dental implants: a pilot histological investigation.

Aim To test whether guided bone regeneration ( GBR) of peri-implant defects at zirconia (ZrO2) implants differs from GBR at titanium (Ti) implants regarding the bone integration of the implant and of the grafting material. Materials and methods Maxillary premolars and molars were extracted in seven dogs. After 5 months, four semi-saddle bone defects were created in each maxilla. Implant placement and simultaneous GBR were performed using the following randomly assigned modalities: (1) ZrO2 implant + deproteinized bovine bone mineral ( DBBM) granules + a collagen membrane ( CM), (2) ZrO2 implant + DBBM with 10% collagen matrix + CM, (3) ZrO2 implant + DBBM block + CM, and (4) Ti implant + DBBM granules + CM. After 3 months, one central histological section of each site was prepared. Histomorphometrical assessments were performed evaluating the augmented area ( AA) within the former bone defect (primary outcome), the area of new bone ( NB), bone substitute ( BS), and non-mineralized tissue ( NMT) within AA in mm2. In addition, the distance between the most coronal bone-to-implant contact and the margin of the former bone defect ( fBIC- DEF), and the bone-to-implant contact fraction ( BIC) were measured in mm. Results AA measured 8.6 ± 4.0 mm2 for ZrO2 implant + DBBM granules, 4.7 ± 1.6 mm2 for ZrO2 implant + DBBM-collagen, 5.1 ± 1.9 mm2 for ZrO2 implant + DBBM block, and 7.6 ± 2.8 mm2 for Ti implant + DBBM granules. There were no statistically significant differences between the treatment modalities ( P > 0.05). NB reached 2.0 ± 1.7 mm2 for ZrO2 implant + DBBM granules, 0.9 ± 0.9 mm2 for ZrO2 implant + DBBM-collagen, 2.1 ± 0.9 mm2 for ZrO2 implant + DBBM block, and 0.8 ± 0.6 mm2 for Ti implant + DBBM granules. fBIC- DEF amounted to 2.1 ± 1.7 mm2 for ZrO2 implant + DBBM granules, to 2.7 ± 1.1 mm2 for ZrO2 implant + DBBM-collagen, to 2.9 ± 1.2 mm2 for ZrO2 implant + DBBM block, and to 3.4 ± 0.4 mm2 for Ti implant + DBBM granules. BIC measured 70 ± 19% for ZrO2 implant + DBBM granules, 69 ± 22% for ZrO2 implant + DBBM-collagen, 77 ± 30% for ZrO2 implant + DBBM block, and 66 ± 27% for Ti implant + DBBM granules. Conclusions The findings of the present pilot study suggest that zirconia and titanium implants grafted with DBBM granules and covered with a collagen membrane do not perform differently regarding the augmented ridge contour, the NB formation, and the implant osseointegration. [ABSTRACT FROM AUTHOR]