Hemostatic Gelatin Sponge Versus Collagen Matrix in Alveolar Ridge Preservation

Patients in need of extraction of two teeth followed by implant replacement, with \> 50% buccal bone present following tooth extraction and with 1 or 2 neighbouring teeth present, were invited to participate in an intra-subject RCT comparing hemostatic gelatin sponge to collagen matrix as socket seal in alveolar ridge preservation. The sample size calculation indicated 16 patients to be included per group. To compensate for dropouts, this number was increased to 20 patients per group. Coincidence (coin flip) determined which site is treated with the gelatine sponge and which with the collagen matrix. Teeth were extracted without flap elevation. When deemed necessary by the clinician, papillary incisions were made for minimal reflection, which enabled to place elevators without damaging soft tissues. Buccal soft tissues were never raised. Following wound debridement and rinsing, the alveolar socket was filled with collagen-enriched deproteinized bovine bone mineral (C-DBBM, Bio-Oss Collagen® 100 mg or 250 mg, Geistlich Pharma AG, Wolhusen, Switzerland) up to the level of the oral bone crest. Subsequently, a collagen matrix (Mucograft Seal®, Geistlich Pharma AG, Wolhusen, Switzerland) or gelatin spons (Spongostan Dental® 1x1x1 cm, Ethicon, Johnson \& Johnson, New Brunswick, VS) was sutured on top with 4 to 6 single sutures (Seralon 6/0, Serag Weissner, Naila, Germany) to protect the underlying C-DBBM. Changes in soft tissue height at the buccal and oral aspect is the primary outcome. A small-field low-dose CBCT image was taken at T0 (immediately postop) and T3 (4 months). Those images were superimposed in specialized software (OnDemand3D, Cybermed Inc., Seoul, South-Korea). Changes in soft tissue height were calculated by subtracting soft tissue height at T3 from soft tissue height at T0. Secondary outcomes included wound healing and closure in the first three weeks, changes in hard and soft tissues and mucosal scarring after 4 months.