Statement of problem: Orientation of occlusal plane for edentulous complete denture patients, considered to be one of the most important bases for excellent prognosis, also occlusion of implants installed in mandible play an important role in success and longevity of complete mandibular overdenture.
Objective: The aim of this study was to evaluate the effect of different occlusal plane orientation on masticatory performance and phonetics in implant supported mandibular overdenture.
Materials and methods: Fourteen completely edentulous patients were selected to participate in this study, the patients were divided randomly into two groups after implants were placed in the canine region by 4 months, according to the type of occlusal plane oriented. Group I patients received overdenture constructed with posterior occlusal plane adjusted parallel to camper's line while group II the occlusal plane was adjusted to coincide with 2/3 the height of retromolar pad posteriorly and corners of mouth anteriorly. Masticatory efficiency and speech analysis were evaluated after one week and then one month following overdenture insertion, the results were collected, tabulated and statistically analysed.
Results: ANOVA test revealed statistically non-significant difference between the two groups during chewing the soft food. While there is a significant difference between the two groups during chewing the hard food. Voice onset time, After one week and after one month, there was no significant difference between both groups for (v) and (f) sounds, while significant difference as regard values of voice onset time in different follow up intervals in each group.