Resorbable membranes are well described and employed for horizontal guided bone regeneration (GBR). However, the currently available literature does not provide information on the bone volumetric changes during the healing that follows GBR procedures and dental implant placement. Therefore, the aim of this pilot study was to initially analyze the volumetric bone changes after treating pristine edentulous mandibular defects with lateral GBR using freeze-dried bone allograft (FDBA) and collagen resorbable membrane. Six patients were selected for the analysis. Clinical changes in bone volume before and after GBR were measured. In addition, digital volumetric analysis of the augmented ridges was performed preoperatively, as well as 4 and 6 months after the GBR procedure. At the time of dental implant placement, bone cores were collected during the osteotomy for histologic analysis. Data on volume changes showed a mean of 297.5 ± 134 mm3 augmented bone volume at 4 months with 5% ± 3.78% resorption from 4 to ≥ 6 months. Histologic bone core analysis showed 44.9% ± 5.1% mineralization in the area of augmentation. Within the limitations of this pilot study, resorbable membranes exhibited reliability for GBR in intercalated mandibular defects, providing sufficient bone volume gain at ≥ 6 months for implant stabilization and limited resorption during graft healing. Keywords: 3D, bone graft, dental implants, guided bone regeneration, histomorphometry, volumetric