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

Abstract

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. Maxillary premolars and molars were extracted in seven dogs. After 5months, 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 3months, 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. AA measured 8.6±4.0mm2 for ZrO2 implant+DBBM granules, 4.7±1.6mm2 for ZrO2 implant+DBBM-collagen, 5.1±1.9mm2 for ZrO2 implant+DBBM block, and 7.6±2.8mm2 for Ti implant+DBBM granules. There were no statistically significant differences between the treatment modalities (P>0.05). NB reached 2.0±1.7mm2 for ZrO2 implant+DBBM granules, 0.9±0.9mm2 for ZrO2 implant+DBBM-collagen, 2.1±0.9mm2 for ZrO2 implant+DBBM block, and 0.8±0.6mm2 for Ti implant+DBBM granules. fBIC-DEF amounted to 2.1±1.7mm2 for ZrO2 implant+DBBM granules, to 2.7±1.1mm2 for ZrO2 implant+DBBM-collagen, to 2.9±1.2mm2 for ZrO2 implant+DBBM block, and to 3.4±0.4mm2 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. 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.