Managing Peri-Implant Soft Tissue: Plastic Surgery and Protocols for Long-Term Stability

The quality of peri-implant soft tissue is a fundamental determinant of both aesthetic outcome and the implant's long-term biological prognosis. The traditional paradigm identifying keratinization as an essential requirement for implant maintenance has been replaced by a more nuanced understanding that considers mucosal biotype — meaning the combination of keratinized tissue quantity, vertical mucosal thickness, and connective tissue composition — as a more accurate predictive parameter. The distinction between "thick-flat" and "thin-scalloped" phenotype in the implant planning approach isn't aesthetic but biological: thick tissue shows a more predictable healing response, lower risk of post-loading peri-implant recession, and greater resistance to prosthetic trauma.

Peri-implant keratinized mucosa width (KMW) has been debated for decades. Lin et al.'s meta-analysis (J Periodontol, 2013) documented significantly higher bleeding-on-probing rates (OR 2.1) in implants with KMW <2 mm compared to those with KMW ≥2 mm, regardless of hygiene quality. The proposed mechanism is greater mobility of the adjacent non-keratinized alveolar tissue which, with the functional movements of opening and closing, exerts tension on the peri-implant mucosal junction — analogous to the epithelial junction zone — favoring pocket formation and bacterial invasion. The clinical threshold of 2 mm of KMW is therefore frequently adopted as the intervention criterion for pre- or peri-implant mucosal augmentation surgery.

Peri-implant mucosal thickness — measured clinically by vertical probing under local anesthesia or with tissue ultrasonography (Pictor® Plus, ISOMED) — determines the amount of expected peri-implant bone resorption after placing prosthetic components. The concept of an implant "biological width" — analogous to the periodontal biological attachment — occupies roughly 3-4 vertical mm coronoapically. When mucosal biotype is thinner than this height (thin mucosa, <2 mm thick), the system will resorb crestal bone to "create" the necessary biological space, resulting in exposure of the first implant thread and potential aesthetic compromise. Preventive treatment — submucosal connective tissue grafting before or at the same time as implant placement — increases mucosal thickness by an average of 0.8-1.8 mm (Thoma et al. review, J Clin Periodontol, 2018), preventing bone resorption mediated by inadequate biological width.

Connective tissue grafting techniques for increasing peri-implant mucosal biotype include the connective tissue graft (CTG) with palatal harvesting, the free gingival graft (FGG), and porcine- or bovine-derived collagen xenografts (Mucoderm®, Mucograft®). Palatal CTG — the harvest site of choice for the quality of its dense connective tissue — is taken using a two-parallel-incision technique or the "trap-door" technique, at a harvest depth of 1.5-2 mm beneath the epithelium (to include the dense submucosal connective tissue, rich in thick collagen fibers and low in cells). The ideal timing for CTG is the day of implant placement, with the receiving site prepared as a tunnel or pouch flap: this choice allows simultaneously increasing biotype and positioning the mucosal margin coronal to the implant level, without the access limitations of a pre-healed site.

Managing peri-implant mucosal recession — a late complication with a prevalence of 7-26% at 5 years depending on implant three-dimensional position, biotype and prosthetic characteristics — requires a treatment strategy tailored to the cause. Recessions of biological etiology (peri-implantitis with concurrent bone loss) require treating the infectious component before any mucogingival intervention. Recessions of mechanical/malposition etiology (implant placed too labially, overcontoured restoration exerting pressure on the mucosal margin) require correcting the mechanical cause — prosthetic modification or, in severe cases, explantation and repositioning. Isolated post-surgical recessions, without bone loss and with favorable anatomy, can benefit from root-coverage techniques adapted to the implant site: the subcrestal tunnel with CTG is the technique with the most favorable evidence, with complete coverage documented in 68-79% of treated sites (Zucchelli et al., 2019).

The emergence profile of the implant prosthetic component — the shape of the transition between the implant collar and the prosthetic crown — directly and continuously shapes peri-implant soft tissue. A convex emergence profile exerting pressure on peri-implant mucosa favors recession; a concave or straight profile allows soft tissue to mature into a stable anatomical shape. Designing the emergence profile with the implant provisional (provisional-driven implant planning) — through progressively widened profiles over the first 6-8 weeks of provisional loading — is the most effective technique for conditioning soft tissue toward a shape favorable to long-term stability and the aesthetics of the final restoration.