This study evaluates and compares the mechanical behavior of two collagen membranes in an in vitro model simulating membrane-stabilized horizontal guided bone regeneration (GBR). Megreen ® (bovine pericardium, BP) and Bio-Gide ® (porcine dermis, PD) were tested under wet conditions. Two models were developed: (1) a balloon dilation test to assess the membrane’s capability to accommodate bone graft material and (2) a bone graft compression model to evaluate tear resistance during graft compaction