Surgical Protocol for Prevention of Mucositis

The main goal of implant therapy is to obtain long-term peri-implant health. Among local risk factors in the etiology of peri-implant diseases the absence of keratinized tissue (KT) around the implant has been reported. In fact, a certain amount of KT width, providing better sensory isolation and, hence, less pain discomfort during brushing, may be useful to facilitate plaque control. A good plaque control should maintain periimplant health during time.

A very recent systematic review assessed the effect of soft tissue grafting procedures on peri-implant health, revealing that soft tissue grafting using autogenous tissue for gain of KT results in a significant decrease of PI, BOP and GI values and significantly lower PI and GI values and higher marginal bone levels at the study endpoint compared to maintenance groups.

Based in the available data in literature, it has been demonstrated that the level of brushing discomfort was significantly higher in sites with \<2 mm of KT width, which exhibited more plaque and more bleeding on probing than sites with ≥2 mm of KT width. Therefore, various procedures and materials were proposed in the past to augment the soft tissues around dental implant. Soft-tissue grafting seems beneficial, especially in posterior mandible, when patients complains of soreness during oral hygiene procedures and plaque control is less than ideal and it may be facilitated by a better topography. The surgical procedures most frequently used to increase the width of keratinized tissue around an implant-supported restoration include an apically positioned split-flap/vestibuloplasty (APF) with or without the application of autogenous tissue (i.e., free gingival graft) or a xenogeneic collagen matrix.

However, it remains unclear whether or not surgical procedures for gain of KT may establish peri-implant health limiting the incidence of peri-implant disease and may positively affect self-performed oral hygiene measures reducing peri-implant soft tissue inflammation when compared with non-augmented, inadequately dimensioned implant sites. Neither do clinical suggestions exist for a specific soft tissue transplant to obtain more favorable outcomes.

The aim of the present randomized controlled clinical trial is to assess the effect of soft tissue augmentation procedures at diseased (mucositis) implant sites in terms of:

* occurrence of peri-implant health (absence of BoP/suppuration, PPD\>6mm, longitudinal radiographic bone loss) at 3, 6 and 12 months
* reduction of BoP (%) at 3, 6 and 12 months
* marginal bone loss (MBL) at 12 months
* improvement of self-performed oral hygiene measures (PI, VAS) at 3, 6 and 12 months and post-operative morbidity (VAS) at 7 days.
* change in tissue morphology: increase of KT width (2D in mm.) and tissue volume (volumetric 3D) at 3, 6 and 12 months and aesthetic (blinder examiner) at 6, 12 months.

Eligibility Criteria:
Inclusion Criteria:

* Systemic healthy patients
* appropriate oral hygiene standards (full mouth plaque scores \<20%)
* periodontal health (BoP \< 10%) or gingivitis (BoP \> 10%) in a healthy or reduced periodontium
* clinical signs of mucositis (presence of BoP) at the affected implant-supported fixed prosthesis
* \< 2mm of KT at the mid-buccal aspect of implant-supported fixed prosthesis
* \< 10 cigarette/die

Exclusion Criteria:

* any systemic disease that would negatively influence wound healing or known allergy to collagen
* more than 10 cigarettes/day
* sites with implant-supported rehabilitations presenting poor marginal adaptation (confirmed by an explorative probe and radiographic examination)
* implant-supported rehabilitations with inadequate access to hygiene