1. perforation: perforation of gingival tissue covering the implant in the healing stage, which may be caused by excessive tension of the flap during suture and poor suture; Or suture residue stimulates granulation tissue proliferation; It may also be due to the compression of the prosthesis, which leads to gingival bedsore ulcer. 2. Gingivitis: caused by poor oral hygiene and dental plaque irritation. At this time, there was no obvious hyperplasia of gingival tissue. 4. Fistula formation: Fistula on mucosa is related to inflammation around abutment or implant. It often occurs when gingival tissue covers the junction of abutment and bridge.