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 (ZrO(2) ) 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) ZrO(2) implant + deproteinized bovine bone mineral (DBBM) granules + a collagen membrane (CM), (2) ZrO(2) implant + DBBM with 10% collagen matrix + CM, (3) ZrO(2) 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 mm(2) . 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 mm(2) for ZrO(2) implant + DBBM granules, 4.7 +/- 1.6 mm(2) for ZrO(2) implant + DBBM-collagen, 5.1 +/- 1.9 mm(2) for ZrO(2) implant + DBBM block, and 7.6 +/- 2.8 mm(2) for Ti implant + DBBM granules. There were no statistically significant differences between the treatment modalities (P > 0.05). NB reached 2.0 +/- 1.7 mm(2) for ZrO(2) implant + DBBM granules, 0.9 +/- 0.9 mm(2) for ZrO(2) implant + DBBM-collagen, 2.1 +/- 0.9 mm(2) for ZrO(2) implant + DBBM block, and 0.8 +/- 0.6 mm(2) for Ti implant + DBBM granules. fBIC-DEF amounted to 2.1 +/- 1.7 mm(2) for ZrO(2) implant + DBBM granules, to 2.7 +/- 1.1 mm(2) for ZrO(2) implant + DBBM-collagen, to 2.9 +/- 1.2 mm(2) for ZrO(2) implant + DBBM block, and to 3.4 +/- 0.4 mm(2) for Ti implant + DBBM granules. BIC measured 70 +/- 19% for ZrO(2) implant + DBBM granules, 69 +/- 22% for ZrO(2) implant + DBBM-collagen, 77 +/- 30% for ZrO(2) 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.