1. ? To measure the alveolar resorption processes that occur in patients wearing mandibular overdentures on 2 implants and fully-removable maxillary dentures, and to evaluate the same process on patients wearing fullyremovable dentures on both arches. 2.- To verify whether Kelly?s Combination Syndrome occurs in the group of patients wearing overdentures. Method and Material: Forty patients were evaluated, of which a ?cases? group was formed by 25 patients wearing mandibular overdentures on 2 lower jaw implants and fully-removable dentures on the opposite arch. The other 15 patients formed a control group that wore fully-removable dentures on both arches. Each one of the patients underwent orthopantograms from the moment the dentures were inserted until an average of 6 years later, which were assessed based on the Xie et al. method to estimate vertical bone loss. Once the data was collected, it was subjected to statistical analysis. Results: In terms of the maxillary midline, we observed a greater loss in patients wearing overdentures, which was statistically significant, as it registered 0.32 mm/year. Mandibular bone loss was 2.5 times less in patients in the cases group. The rest of the clinical criteria for Kelly?s Combination Syndrome were not observed. Conclusions: Kelly?s Combination Syndrome did not occur in the patients in the cases group. In spite of the greater bone loss on a premaxillary level in this group, the placing of the overdenture on the implants significantly reduced mandibular bone resorption.