Comparison of Envelope Coronally Advanced Flap and Modified Tunnel Technique in Soft Tissue Dehiscence Around Implants

Inclusion Criteria: * Age ≥ 18 years * Periodontally and systemically healthy * Full-mouth plaque score and full-mouth bleeding score ≤ 20% (measured at four sites per tooth) * Correct implant 3-dimensional position or buccal position ≤ 1 mm * Buccal soft tissue dehiscence ≤ 4 mm * Only osseointegrated implants * The patient must be able to perform good oral hygiene Exclusion Criteria: * Contraindications for periodontal surgery * Patients pregnant or attempting to get pregnant * Malpositioned implant * Soft tissue dehiscence (STD) \> 4 mm * Multiple adjacent implants with STD * Existing of peri-implantitis * Severe bone loss (≥4mm) * Moderate-severe interproximal bone loss (implant fixture level to the alveolar bone \> 3 mm) * Moderate-severe papilla height loss (Nordland and Tarnow implant papillae index \>1) * Previous mucogingival surgery around the implant within the past six months or implant placement at the surgical site less than six months prior * Smoking more than 10 cigarettes a day