A Randomized Controlled Trial Comparing Collagen Matrix to Collagen Membrane as Socket Seal in Alveolar Ridge Preservation

The primary study objective is to compare soft tissue thickness in the centre of the site between collagen matrix and collagen membrane at 4 months following ARP.

Secondary study outcomes relate to the same comparison and include the following variables: wound reduction after 7 days and 21 days, socket wound healing score after 7 days, 21 days and 4 months, changes in bone and soft tissue dimensions including soft tissue profile between pre-op and 4 months.

Patients will be included in an intra-subject RCT on ARP following screening and written consent at the Department of Periodontology and Oral Implantology of the University Hospital in Ghent.

A sample size calculation was performed in SPSS Statistics 28 (IBM, New York, USA) using the paired samples t-test. The calculation was based on finding a mean difference of 0.5 mm in the final soft tissue thickness between test and control sites with a standard deviation of 0.6 mm (Eeckhout et al., 2022). With alpha set at 0.05 and a power of 0.08, the sample size calculation indicated 14 patients to be included. To compensate for possible dropouts, this number was increased to 18 patients.

Randomization, allocation concealment and blinding Since this is an intra-subject RCT, every patient receives the test treatment as well as the control treatment. A coin flip will determine which site in each patient is treated with the collagen matrix (test site) and which one with the collagen membrane (control site). Group allocation will be determined just after ARP and remains concealed for the evaluating examiner and statistician to allow for unbiased registrations and analyses, respectively.