Adjunctive Benefit of a Xenogenic Collagen Matrix

This is a single-centre, superiority, double blind clinical trial, with balanced randomisation and parallel two groups design. The 2 groups will be:

• CAF combined with XCM;
• CAF alone.

The objective is therefore to assess the adjunctive benefit of a xenogenic collagen matrix in combination with a coronal advanced flap.

The primary endpoint is the mean recession reduction after 6 and 12 months post treatment.

The secondary endpoints are: Percentage of complete root coverage after 6 and 12 month; Thickness of soft tissue over the root after 6 and 12 month; Recession width after 6 and 12 month; KT width; Patients satisfaction.

The following Inclusion Criteria have to be satisfied: patient (male or female) must be 18 years or older, not pregnant, and candidate for buccal root coverage procedure in the upper jaw; recession defects have to be AAA or ABA (according to Rotundo et al classification), with at least 2 adjacent RC with ≥ 2 mm RC depth and root abrasion depth less than 1 mm; Patient shows sufficient plaque control (FMPS ≤ 20%) and acceptable bleeding score(FMBS ≤ 20%); Teeth intended to treat are in the region 1 - 5; patient has to be able to comply with the study-related procedures such as exercising good oral hygiene and attending all follow-up procedures; patient is able to fully understand the nature of the proposed surgery and is able to provide a signed informed consent.

Randomisation: Computer-generated blocked for each centre, with allocation concealment by opaque sequentially numbered sealed envelopes.

Blinding: Patients and outcome assessor blind to group assignment.

Sample size: Based on a formula for cluster design to detect a difference between treatments of 1 mm in recession reduction (standard deviation of 0.93 mm - Woodyard et al. 2004) with a two-side 5% significance level, a power of 90%, a mean number of treated teeth per patient of 2.92, an intraclass correlation coefficient of 0.35, a sample size of 24 patients per treatment will be necessary.

Inclusion criteria

• The patient (male or female) must be 18 years or older
• Presence of gingival recessions in the upper jaw, involving teeth from central incisor to first molar
• Gingival recessions on at least 2 adjacent teeth with a minimal depth of 2mm and detectable cemento-enamel junction (CEJ) (abrasion step <1mm)
• The patient is able to comply with the study-related procedures such as exercising good oral hygiene and attending all follow-up procedures
• Full Mouth Plaque (FMPS) and Bleeding (FMBS) Score <20%
• The patient is able to fully understand the nature of the proposed surgery and is able to provide a signed informed consent

Exclusion criteria

• Smoker patients
• Pregnant patients
• Patients affect by uncontrolled diabetes
• General contraindications for dental and/or surgical treatment are present
• History of malignancy, radiotherapy, or chemotherapy for malignancy within the past 5 years
• The patient is taking medications or having treatments which have an effect on mucosal healing in general (e.g. steroids, large doses of anti-inflammatory drugs, anticoagulation drugs)
• The patient has a disease, which affects connective tissue metabolism (e.g. collagenases)
• The patient is allergic to collagen
• The patient is an abuser of alcohol or drug
• Patients have participated in a clinical trial within the last six months
• Presence of untreated periodontitis
• Gingival recessions on molar teeth (excluding the first) or on malpositioned teeth
• Presence of abrasion ≥ 1 mm or cervical restoration, with non-detectable CEJ