To review systematically the bone gain and superficial resorption rate of the onlay block bone grafts versus the cortical tenting technique, as well as secondarily study the postoperative complications, implant survival and success rates, and peri-implant marginal bone loss. Following the recommended methods for systematic reviews and meta-analyses (PRISMA), an electronic search was performed in the PubMed (MEDLINE), EMBASE and the Cochrane Library of the Cochrane Collaboration (CENTRAL) databases to identify all relevant articles published up to March 2021 on onlay block bone grafts and cortical tenting technique. Eighteen papers complied with the inclusion criteria. In onlay grafts, the vertical bone gain mean was 4.24 mm, and resorption 20.91%; and 4.29 mm in the horizontal augmentation with a resorption of 10.28%. The complication rate was 14.8%. The implant survival and success rates were 100% and 92%; and the mean peri-implant bone loss ranged from 0.6 to 1.26 mm. In cortical tenting technique, the vertical bone gain mean was 6.17 mm and the resorption of 9.99%; and 5.55 mm in the horizontal augmentation with a 6.12% of resorption. The complication rate was 24.6%. The implant survival and success rates were 96.63% and 100%; and the mean peri-implant bone loss ranged from 0.27 to 0.77mm. Despite the limitations, both techniques offer a predicTable way to reconstruct atrophic alveolar ridges, though the cortical tenting technique seems to achieve a greater bone gain and a lower surface resorption. Current evidence is still limited due to the inadequate follow-up, lack of information referred to methodological quality and sample attrition.