Soft tissue reconstructive techniques at implant sites

Dental implants have shown to be a reliable tool for single, multiple and full-arch rehabilitations 1. Dental implants have a very high success rate in terms of osseointegration, however biological, prosthetic and esthetic complications are not rare. While the significance of peri-implant bone volume and the necessity of performing bone augmentation if deficient, has been extensively discussed 2, 3, the critical role of peri-implant soft tissue on implant esthetics and health has also been the topic of significant discussion in the last decade 4. The peri-implant phenotype has been defined recently by Avila-Ortiz et al. as the morphologic and dimensional features characterizing the clinical presentation of the tissues that surround and support osseointegrated implants 5. The peri-implant phenotype encompasses a soft tissue component, which includes the peri-implant keratinized mucosa width (KMW), the mucosal thickness (MT) and the supracrestal tissue height (STH), and an osseous component, characterized by the peri-implant bone thickness (BBT). This definition does not only apply to buccal and facial sites, but also to lingual and palatal peri-implant locations. Like the periodontal phenotype 6, the peri-implant phenotype is site-specific and may change over time in response to environmental factors 5. Peri-implant keratinized mucosa width is the height of keratinized tissue in an apico-coronal direction between the soft tissue margin and the mucogingival junction (MGJ). KMW may be completely absent in certain cases in which there is only alveolar mucosa surrounding the implant(s) 5. While several investigators have shown that an insufficient KMW around dental implants is associated with more plaque accumulation, tissue inflammation, mucosal recession and attachment loss 7-11, others have failed to reach such conclusions 12-14. However, recent evidence seems to suggest that KMW plays a protective effect on peri-implant tissues. In a 10-year prospective study, Roccuzzo et al. observed significantly greater plaque accumulation and deeper mucosal recession (peri-implant soft tissue dehiscence [PSTD]) for implants without KMW. In addition, more sites from the group of implants without KMW required additional treatment, including surgeries with free gingival graft (FGG) or antibiotics. Patients with implants without KMW that received FGG reported reduced discomfort and showed better plaque control 15. Souza et al. confirmed that KMW plays a role on patient brushing comfort 16. More recently, a 4-year prospective study by Perussolo and coworkers showed that implant with narrow KMW width (< 2 mm) had higher level of brushing discomfort, plaque index and bleeding on probing than implants with wide KMW (≥ 2 mm). In addition, implants with narrow KMW were found to have higher marginal bone loss, leading the authors to conclude that KMW width ≥ 2 mm may have a protective effect on peri-implant tissues 9. In a cross-sectional study, it was found that reduced KMW width is a risk indicator for the severity of peri-implant mucositis, 7 and in line with this finding, Schwarz et al. concluded that KMW plays a role on the prevention and resolution of peri-implant mucositis 17. Furthermore, the absence of peri-implant KMW has also been related to lower patient esthetic satisfaction 18, verifying the importance of the soft tissue component on implant esthetics 19, 20.