Bar Versus Locator Implant Assisted Maxillary Overdentures Opposing Two Implants Retained Mandible Overdentures: A Study of Chewing Efficiency and Electromyographic Activity

Two implants retained mandibular overdenture opposing conventional maxillary complete denture may induce a combination syndrome, implant supported maxillary overdenture was indicated to avoid this phenomena. Selection of splint or solitary attachment for this issue is a matter of debate.This study aimed to compare and evaluate chewing efficiency and electromyographic activity of patients wearing implant assisted maxillary overdentures by bar versus locator attachments opposing two implants retained mandibular over dentures. Six completely edentulous healthy male patients were selected for this study .After three months of conventional complete denture construction, the electromyographic (EMG) activity of masseter muscle and chewing efficiency measured by unmixed fractions of (UF) of double colored chewing gum were evaluated(Group I): ( control group). Two implants were installed bilaterally in the mandibular canines areas; and four implants were installed in the maxilla. After the osseointegeration period, bar assisted maxillary overdenture was constructed against mandibular locator retained overdenture and the (UF) and EMG were evaluated after three months (Group II) . After two weeks resting period, the bar attachments in was replaced by locator attachments (Group III) and the evaluation was done after three months of denture insertion. After two weeks resting period , the bar in group II was replaced by locator and the locator in group III was replaced be bar attachment to evaluate the (UF) and EMG after three months of replacement.Statistically significant difference in (UF) and ( EMG) activity of masseter muscle between implant assisted overdenture and conventional complete denture groups. 2- A statistically insignificant difference in(UF) and ( EMG) activity of masseter muscle between bar and locator assisted maxillary overdentures. Four implant assisted maxillary overdentures opposed by two implant retained mandibular overdentures significantly improve the chewing efficiency and EMG activity of masseter muscle compared with conventional complete dentures regardless the attachment design( splint bar or solitary locator) used for the maxillary overdenture.