Timing of implant placement and augmentation with bone replacement material: clinical assessment at 8 and 16 months.

PURPOSE The purpose of this study is to evaluate implants placed at different times of bone augmentation. MATERIALS AND METHODS Four implants were placed in seven dogs: one at a 6-month bovine mineral grafted site (6-month Bio-Oss® grafted site [6mBio]), one at a grafted membrane-protected simultaneously augmented (Fresh Bio-Oss® grafted site [FrBio]) site, one at a clotted (nongrafted clotted membrane-protected site [Clot]) membrane-protected site, and one at a pristine (nongrafted uncovered site [Cont]) site. Implants were exposed after 6 months. The same protocol was repeated on the contralateral side, at a delay of 8 months. Peri-implant care was performed throughout the hygienic phase (2 and 10 months, respectively) every 48 to 72 hours. Probing depth and bleeding on probing were recorded. Implant stability was determined by a Periotest® (Medizintechnik Gulden, Modautal, Germany). Statistical analysis was conducted using analysis of variance with repeated measures. RESULTS Average probing depth at the simultaneously grafted sites was 2.21 mm and 2.03 mm at 8 and 16 months, respectively. At the 6-month grafted sites, it was 1.96 mm and 1.57 mm. At the Clot sites, it was 2.68 mm and 2.07 mm, and 2.21 mm and 1.82 mm at the Cont sites, respectively. The average bleeding on probing was 0.50 and 0.42 at the FrBio sites, and 0.35 and 0.07 at the 6mBio sites during the respective periods. At the Clot sites, it was 0.50 and 0.28, and at the Cont sites, 0.43 and 0.21, respectively. Probing depth significantly reduced over the time at 6mBio, Clot, and Cont sites (p < .03). Average implant stability score at the FrBio sites was -0.24 and -0.27, and -0.50 and -0.46 at the 6mBio sites, at 8 and 16 months, respectively. At the Clot sites, it was -0.35 and -0.46. Cont sites averaged -0.37 at both periods. Implant stability was significantly higher (p < .005) comparing 6mBio over FrBio, 6mBio over Cont, and Clot over FrBio sites. CONCLUSIONS Immediate and delayed augmentations are safe modes. Probing depth and bleeding indices gradually improved along time. Implant stability was higher at the delayed mode.