title: Soft tissue augmentation procedures at second-stage surgery: a systematic review.
abstract: OBJECTIVE
  The aim of this systematic review was to evaluate the efficacy of different soft tissue augmentation/correction methods in terms of increasing the peri-implant width of keratinized mucosa (KM) and/or gain of soft tissue volume during second-stage surgery.
  
  
  METHODS
  Screening of two databases, MEDLINE (PubMed) and EMBASE (OVID), and hand search of related articles, were performed. Human studies reporting on soft tissue augmentation/correction methods around submucosally osseointegrated implants during second-stage surgery up to July 31, 2015 were considered. Quality assessment of the selected full-text articles was performed according to the Cochrane collaboration's tool to assess the risk of bias.
  
  
  RESULTS
  Overall, eight prospective studies (risk of bias: high) and two case series (risk of bias: high) were included. Depending on the surgical technique and graft material used, the enlargement of keratinized tissue (KT) ranged between -0.20 and 9.35 mm. An apically positioned partial-thickness flap/vestibuloplasty (APPTF/VP) in combination with a free gingival graft (FGG) or a xenogeneic graft material (XCM) was most effective. Applying a roll envelope flap (REF) or an APPTF in combination with a subepithelial connective tissue graft (SCTG), mean increases in soft tissue volumes of 2.41 and 3.10 mm, respectively, were achieved. Due to the heterogeneity of study designs, no meta-analysis could be performed.
  
  
  CONCLUSIONS
  Within the limitations of this review, regarding the enlargement of peri-implant KT, the APPTF in the maxilla and the APPTF/VP in combination with FGG or XCM in the lower and upper jaw seem to provide acceptable outcomes. To augment peri-implant soft tissue volume REF in the maxilla or APPTF + SCTG in the lower and upper jaw appear to be reliable treatment options.
  
  
  CONCLUSIONS
  The localization in the jaw and the clinical situation are crucial for the decision which second-stage procedure should be applied.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Lucerne Cantonal Hospital, Spitalstrasse, 6000, Lucerne, Switzerland. renzo.bassetti@luks.ch.
authors.forename: Renzo G
authors.initials: RG
authors.lastname: Bassetti
authors.affiliation: Department of Periodontology, University of Bern, Bern, Switzerland.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Stähli
authors.affiliation: Department of Periodontology, University of Bern, Bern, Switzerland.
authors.forename: Mario A
authors.initials: MA
authors.lastname: Bassetti
authors.affiliation: Department of Periodontology, University of Bern, Bern, Switzerland.
authors.forename: Anton
authors.initials: A
authors.lastname: Sculean
mesh_terms: D003238:Connective Tissue / Q000637:transplantation; D015921:Dental Implants; D005881:Gingiva / Q000637:transplantation; D005893:Gingivoplasty / Q000379:methods*; D006801:Humans; D007576:Jaw, Edentulous, Partially / Q000601:surgery; D013524:Surgical Flaps; D014727:Vestibuloplasty / Q000379:methods*
chemical_list: D015921:Dental Implants
keywords: Peri-implant keratinized mucosa; Peri-implant soft tissue volume; Re-entry; Second-stage surgery