Evaluation of Alveolar Crest Changes following Buccal Bone Overbuilding in Immediate Implantation

The aim of the present study was to evaluate alveolar crest changes when using demineralized freeze-dried bone allograft (DFDBA) and resorbable membrane between flap and buccal bone in addition to filling the gap, as compared to merely filling the gap, when performing immediate implantation. In 18 patients with 24 single-root teeth, implants were placed immediately after extraction. In the test group (nine patients with 12 teeth), DFDBA and barrier membrane were placed between buccal crest and flap after implant placement. In the control group (nine patients with 12 teeth), implants were placed without buccal grafting. In addition, in both groups, if the gap width between implant and buccal crest was ≥2 mm, the gap was filled with DFDBA at the time of extraction. The height of buccal crest soft tissue and the buccolingual width of bone at 3 and 5 mm, apical to the line connecting the two cementoenamel junctions (CEJs) of adjacent teeth (CEJ line), were measured at baseline and after 4 mo. In the test group, the mean height of the buccal crest increased by 1.04 ± 0.68 mm, but in the control group, height decreased by 0.83 mm (p < 0.001). In the test group, the mean height of soft tissue increased by 0.29 mm, but in the control group, height decreased by 0.79 ± 0.72 mm (p = 0.006). The mean reduction of buccolingual width of bone in 3 and 5 mm apical to the crest in the test group was lower than that of the control group, but not significantly (p = 0.231 and 0.212, respectively). The findings of this study show that using DFDBA and membrane between buccal crest and flap in immediate implantation could increase buccal crest and soft tissue height in the midfacial region but may not significantly prevent buccolingual width reduction of bone at 3 and 5 mm from the CEJ line.