Purpose: This study aimed to compare two treatment modalities; All on four fixed prostheses
and locator retained overdentures; to rehabilitate patients having problems associated with
edentulous maxilla opposing mandibular implant assisted overdentures.
Materials and methods: Ten patients complaining from looseness and instability of their
maxillary dentures that oppose mandibular 2-implant-retained overdentures were randomly
divided into 2 groups: Group I included 5 patients who received four implants according to the
All-on- four Concept (2 parallel middle implants and 2 posterior implants with distal inclination).
Implants were immediately loaded with fixed acrylic prosthesis, then after 6 months the
prosthesis was replaced with fixed ceramometal restoration, Group II, included 5 patients who
received four implants that were immediately loaded with Locator retained maxillary
overdentures using new maxillary dentures. Clinical (plaque index (PI), gingival index (GI),
probing depth (PD) and implant stability (IS)) and radiographic (marginal bone loss (MBL)
outcomes were recorded at baseline (T0), 6 (T6) and 12 (T12) month after prosthesis insertion.