The aim of the present study was to test whether or not one of two GBR membranes is superior to the other in terms of: i) vertical defect resolution and bucco-oral width of regenerated bone at the implant shoulder after 6 months, ii) postoperative complications and during the 6-month follow-up and, iii) histologically assessed newly formed bone at 6 months. In 27 patients, 27 implants were placed in single-tooth gaps. The augmented dehiscence defects were then randomly covered with either a resorbable membrane or a titanium-reinforced non-resorbable membrane. Both treatment modalities were clinically and radiologically effective in regenerating bone on the buccal aspect of single tooth dental implants showing dehiscence- type defects. Despite a higher initial horizontal thickness, sites with the resorbable membrane experienced a significantly higher reduction in bone thickness after 6 months compared to the non- resorbable membrane. Schlagwörter: dental implants, guided bone regeneration, membrane, CBCT