The purpose of this study is to compare the clinical effects of combined application of a xenogeneic collagen matrix and the free gingival graft in augmentation of keratinized tissue around dental implant by single arm clinical trial, compared with historical control group 1:application of a xenogeneic collagen matrix,and historical control group 2:application of the free gingival graft. This study designed a single arm clinical trial. The included patients will all be treated with apical repositioned flap with a xenogeneic collagen matrix and the free gingival graft. The width of keratinized mucosa, thickness of keratinized mucosa, gingival index, probing depth will be measured before surgery and at 2, 6 months postoperatively.
The purpose of this study is to compare the clinical effects of combined application of combined application of a xenogeneic collagen matrix and the free gingival graft in augmentation of keratinized tissue around dental implant by single arm clinical trial, compared with historical control group 1:application of a xenogeneic collagen matrix,and historical control group 2:application of the free gingival graft.