BackgroundThe high resorption rate of intra-oral Onlay block grafts, coupled with morbidity and limited bone availability, means that the use of guided bone regeneration (GBR) may be preferable for vertical augmentation of mandibular atrophic posterior sectors. Aims: To evaluate the bone gain and surface resorption of the intraoral Onlay block graft compared to the GBR; as well as to study postoperative complications, survival and success rates of dental implant, and peri-implant marginal bone loss.Material and MethodsAn electronic search was performed in the PubMed, Scopus, and Web Of Science databases on bone augmentation with intraoral autologous onlay block graft or GBR until December 2021.ResultsOf 214 potentially eligible papers, 11 complied with the inclusion criteria: 5 studies on block graft technique, 5 on GBR technique and 1 was a comparison of both treatment groups. In the block graft group, the mean vertical bone gain was 4.05mm with a mean resorption of 0.84mm (17.70%); the complication rate was 20%; the survival and success rates were 100% and 92.23% respectively and the mean peri-implant bone loss was 0.22mm at 12 months. For the GBR group, the mean bone gain was 4.7mm with a mean resorption of 0.33mm (15.08%); the complication rate was 11.6%; the survival rate was 100% and the mean peri-implant bone loss was 0.95mm at 12 months.ConclusionsDespite the limitations, the GBR technique seems to achieve greater bone gain with less superficial resorption as well as fewer complications, but it presents a greater peri-implant loss at 12 months.Key words:Onlay block graft, Guided Bone Regeneration, intraoral bone, augmentation procedure.