Non-Inferiority of Fibroguide Collagen Membrane Compared to Autologous Connective Tissue Graft for Coverage of Multiple Adjacent Recession. Multicenter Trial.

Objectives Primary objective: to assess non-inferiority of differences in root coverage of recession defects comparing the use of Volume Stable Collagen Matrix (VCMX, Geistlich Fibro-Gide®) ed to the use of CTG at 12 months Secondary objectives: to assess if VCMX is non-inferior in terms of complete root coverage, percentage of root coverage and professional evaluation of aesthetics. Moreover, the study is also designed to test if VCMX Geistlich Fibro-Gide® reduces morbidity, shortens time to recovery and improves patient based related outcomes with respect to the use of autologous connective tissue graft harvested from the patient own palate when used to obtain root coverage of multiple adjacent gingival recessions. Moreover, as adverse events, complete root coverage, and professional evaluation of aesthetics will be assessed

Design and Outcomes This will be a parallel group, controlled, assessor-blind, randomized, multicenter, multinational, clinical trial.

The statistical design will be a non-inferiority trial in terms of the professional outcomes measuring root coverage and aesthetics and a superiority trial in terms of patients related outcomes.

Based on a recently completed and published RCT with similar design (Geistlich Mucograft® study), the sample size has been estimated in 80 subjects per treatment arm (about 200 recessions/arm) to be analyzed with a multilevel statistical approach and a non-inferiority margin of 0.25 mm in recession coverage. The non-inferiority margin has been set as 50% of the clinically relevant difference estimated at 0.5 mm.

Randomization will be performed by computer generated random codes, using random permuted blocks with a block size of 4 to avoid uneven splits and minimization for the key prognostic factor cigarette smoking. Allocation will be concealed to the surgeons until completion of preparation of the recipient bed by opaque envelopes. A central study registrar will perform patient registration.

Study locations will include academic centers and a practice-based research network in Italy, Germany, and Spain.

A single examiner, blind with respect to the treatment assignment, will perform all primary outcome measurements at each center. Trained personnel not involved with the surgical intervention will: i) administer patient questionnaires, ii) provide instructions and collect patient diaries. A single calibrated investigator with specific experience in using the specific score will centrally perform assessment of esthetic scores on standardized digital images.

A biostatistician blind with respect to treatment assignment will perform the analysis.

Interventions and Duration The two intervention groups will consist of surgery with connective tissue graft from the palate (standard of care control) and surgery with the application of Geistlich Fibro-Gide®. Experienced clinicians will deliver treatment consisting of root coverage surgery using coronally advanced flaps, the most utilized procedure for coverage of multiple recessions. Surgery will be standardized and the same procedures/materials will be employed to ensure consistency essentially as performed in the completed Mucograft study.

The total duration of the Followfollow-up of individual patients will be up to 1 year and extended to 3 years for the collection of long-term follow-up data.

Sample Size and Study Population Study population will consist of 160 subjects with a minimum of two adjacent RT1 and RT2 (with periodontal attachment <2 mm) recessions of the gingival margin (average 2.5 recessions per subject, of which one should be 3 mm or deeper) requiring surgical intervention for root coverage. Heavy smokers (>10 cigarette/day) will be excluded.