Aim: To investigate the effect of three treatment modalities on the gain of keratinized tissue (KT) at tooth and implant sites in dogs. Materials and Methods: In five dogs, the distal roots of the mandibular second, third and fourth premolars were extracted, while the mesial roots were maintained. After 2 months of healing, implants were placed with KT excision. After another 2 months of healing, free gingival grafts, collagen-based matrices and apically positioned flap only were applied. The height of KT was measured during implant placement, immediately before soft-tissue grafting and after 10, 30 and 60 days. Results: Two months after KT excision, spontaneous KT regrowth was greater at tooth sites than at implant sites (median, 2.0 mm vs. 1.1 mm). The outcomes of soft-tissue grafting at implant sites favoured the free gingival graft treatment, with a greater final median height (5.0–5.5 mm) and increase in KT (4.0–4.2 mm). Locations of the recipient sites significantly influenced KT regeneration at both tooth and implant sites. Conclusions: At implant sites, the free gingival graft treatment led to higher KT regeneration. At tooth sites, however, the differences between the three treatment modalities seemed clinically irrelevant.
Bibliographical noteFunding Information:
Funding information This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (Ministry of Science, ICT & Future Planning) (No. NRF-2017R1A2B2002537). The authors express their thanks to the researchers at the Department of Periodontology, Research Institute of Periodontal Regeneration, Yonsei University, College of Dentistry, Seoul, Korea, for their support during the animal experiments. The extensive statistical advice provided by Prof. Dr. J?rg H?sler (Clinic of Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich) is also highly appreciated. The experimental materials were kindly supplied by Geistlich Pharma.
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