Aim: The purpose of this study was to evaluate clinical and radiographic results of implant supported fixed prosthesis with and without cantilever extensions for “All on four" implant rehabilitation of atrophied mandible.
Materials and methods: Ten completely edentulous individuals with atrophied mandibular ridges were classified into 2 groups: 1) Group I: included 5 patients with posteriorly placed mental foramen, 2) Group II: included 5 patients with anteriorly placed mental foramen. All participants were managed by 4 implants according to the “All on four" protocol using a Nobel Biocare metal guide and open flap surgery. Implants were immediately loaded by existing mandibular dentures. Group I restored with fixed prosthesis without cantilevers, and group II restored with fixed prosthesis with distal short cantilevers. Plaque and gingival index, probing depth, implant mobility and bone loss (using cone beam CT) were evaluated after prosthesis delivery (T0), six months (T6) and 12 months (T12) after delivery
Results: For posterior implants, group II showed significant higher plaque index, and gingival index than group I after 6 and 12 months. No differences in probing depth, implant mobility and bone resorption between groups was noted for anterior and posterior implants. Posterior implant showed significant higher plaque scores (for both groups) and gingival scores (for group II) than anterior implants after 6 and 12 months. Posterior implant showed significant higher pocket depth for both groups.
Conclusion: Within the limitation of this study, fixed prosthesis with short cantilever can be used successfully to rehabilitate patients with atrophied mandibular ridges and anteriorly placed mental foramen with “All on four" concept as it was associated with favourable clinical and radiographic outcomes similar to prosthesis without cantilevers