الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The fitting surface of the mandibular surface was loaded with a thin mix of zinc oxide euginol impression paste .After setting, ridge base distances were measured from reference lines and points drawn on the denture and represents the anterior, middle and posterior ridge-base relations .The distances were measured immediately, 6 and 12 months after denture insertion. The difference between measurements, was calculated and statistically analyzed. The results of this study revealed that: 1-There was statistically insignificant increase in the mean ridge base distance along the whole residual alveolar ridge after the first six months within both groups. 2-There was statistically significant increase in the mean ridge base distance along the whole residual alveolar ridge after the second six months in the functional impression group. However, this increase was statistically significant in the posterior ridge base distance after the second six months in the dual impression group. 3-There was statistically insignificant difference in the mean ridge base distance along the whole residual alveolar ridge between both groups after the first six months. 4-There was statistically insignificant difference in the anterior and middle ridge base distance between both groups after the second six months of the study. However, there was a statistically significant increase in the posterior ridge base distance in dual impression technique group compared to functional group after the second six months of the study. Within the limitation of this study regarding patient number and study time, it could be concluded that: (1)Regardless the impression technique used for the implant retained mandibular overdenture; the ridge base relation was not maintained after the second six months of this study. Therefore, the ridge base relation of implant retained overdenture must be re-established after six months of denture insertion. (2)The impression technique affects the pattern and amount of the ridge base loss. In this study, the dual impression technique demonstrated uneven loss of this relation by increasing the posterior ridge base distance compared to the middle and anterior areas. Although the ridge base relation was not maintained by the functional impression technique after the second six months, it revealed even loss of this relation along the whole residual alveolar ridge. (3)This study recommended a further longitudinal study to monitor the ridge base relation, maintenance of the attachment and prognosis of the implant.