Treatment of edentulous patients is one of the most demanding tasks the dentist can meet in his everyday practice. Implant based methods help to improve functioning of dentures and life quality of so treated patients.The aim of the study was to evaluate the chewing efficiency of patients treated with lower complete implant-supported overdentures and the simultaneous evaluation of treatment results by patients.For the investigation were chosen edentulous patients, treated with upper conventional complete dentures and lower complete overdentures supported on two implants. In this group of patients, were conducted investigations of chewing efficiency changes, based on the Optocal test and overdentures functioning evaluation made by patients in the survey.The objective evaluation of the chewing efficiency indicated the decrease of this value in the five years of observations. Lower complete overdentures supported on implants significantly increased the comfort of chewing of edentulous patients.The results of the study let us to assess positively the result of the therapy using titanium implants and lower complete overdentures. The therapy described significantly increases the life comfort of the edentulous patients. Decreasing chewing efficiency indicated by the research result should be compensated with the dentures maintaining or the prostheses exchange after about five years of use.