Bone Remodeling Around Implants Placed in Fresh Extraction Sockets

The aim of the present experimental study was to evaluate the physiologic bone remodeling in beagle dogs following the placement of small-diameter (3.25 mm) implants in fresh extraction sites. Five 1-year-old beagle dogs that weighed approximately 10 to 13 kg each were used in this study. The third and fourth premolars (P3, P4) were used as experimental teeth, which were hemisected using a fissure bur; the distal roots were removed carefully using forceps. Implants (3.25-mm wide, 10- or 11.5-mm long) were placed in the fresh extraction sockets with the neck of the implant at the level of the buccal bone crest. The dogs were subsequently put to sleep according to the following schedule: one dog 15 days after implant placement, two dogs after 1 month, and the remaining two dogs after 3 months. The distance from the implant shoulder to the bone wall crest was measured at both the buccal and lingual sites. The width of the buccolingual bone crest was measured using a caliper. Assessments were made immediately after root extraction and at 2, 4, and 12 weeks after implant placement. The mean width of the buccolingual bone crest was 4.5 ± 0.5 mm at the time of root extraction. Subsequently, at 2, 4, and 12 weeks after implant placement, the buccolingual bone width was 4.1 ± 0.5 mm, 3.7 ± 0.3 mm, and 3.5 ± 0.7 mm, respectively. Two weeks after implant placement, the lingual bone crest was measured at 0.2 ± 0.3 mm from the implant shoulder, while the buccal bone crest was 0.3 ± 0.3 mm. After 4 weeks of healing, the mean distance from the implant shoulder to the lingual bone crest was 0.1 ± 0.9 mm, compared to 0.4 ± 0.9 mm for the buccal bone crest. After 12 weeks of healing, the bone crest at the lingual sites was -0.3 ± 0.5 mm from the implant shoulder, compared to 0.8 ± 0.3 mm at the buccal sites. The findings from this study show that although vertical bone remodeling was indeed observed, the mean vertical buccal bone resorption was 0.5 mm. It might be suggested, therefore, that the implant position along the lingual wall and the use of implants with a narrow diameter in relation to the extraction socket width play a key role in reducing the rate of vertical bone resorption at the buccal aspect of implants placed in fresh extraction sockets.