Early Buccal Bone Resorption in Areas With or Without Keratinized Tissue and Different Mucosal Thickness at Implants in Healed Sites: An Experimental Animal Study.

AIM: To evaluate early buccal bone resorption (BBR) in areas with or without buccal keratinized tissue (KT), and different mucosal thickness (MT) following implant placement at healed sites. MATERIALS AND METHODS: In 9 beagle dogs, three months following the hemimaxilla third and fourth premolars extraction, full-thickness flaps were elevated and two tissue-level implants were inserted. Before suturing, each dog was randomly assigned into 3 groups (control, non-keratinized tissue, NKT and non-keratinized tissue plus connective tissue graft, NKT-CTG). In both experimental groups (NKT and NKT-CTG), buccal KT was excised. In the NKT-CTG group, a CTG was sutured to the buccal alveolar mucosa flap (BF) and coronally repositioned around the implant neck, while in the NKT group, only the BF was repositioned. BF with a 2 mm KT band was repositioned around the implants in the control group. Buccal bone thickness (BBT), MT and KT width were measured clinically at baseline. Three months later, BBR and MT were analysed histologically. RESULTS: Mucosal thickness at surgery was similar in NKT and control groups (1.33 +/- 0.26 mm and 1.67 +/- 0.52 mm, respectively). In the NKT-CTG group, MT was 2.50 +/- 0.45. The mean BBT measured at the mid-buccal region was about 1 mm in the 3 groups. Three months later, early BBR was observed in all groups, with mean values of 0.91 mm +/- 0.62 (control), 1.11 mm +/- 0.69 (NKT) and 1.10 mm +/- 0.58 (NKT-CTG). The mean values of MT at a 1.5 mm distance from the marginal mucosa were 1.20 mm +/- 0.69 (control), 2.18 mm +/- 0.53 (NKT) and 3.45 mm +/- 1.33 (NKT-CTG). CONCLUSIONS: Within the limitations of the present investigation, the presence or absence of KT did not affect early BBR. CTG placed in the zones without KT did not prevent early BBR.