The purpose of this in-vitro study was to evaluate adaptation and stresses induced over the abutment teeth and residual ridge through different designs of maxillary major connectors. Materials and methods: An acrylic resin model was fabricated and three different designs of upper major connectors were constructed, the first design was anterior palatal strap, the second design was anterior palatal bar and the third design was anterior-posterior palatal strap. Stress analysis was evaluated using

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... train gauge and strain developed was recorded. The adaptation was measured by Leica Micro System LTd, made in Germany. Data were calculated, tabulated and analyzed using statistical ANOVA test to compare between the last 10 readings obtained from the different designs when unilaterally and bilaterally loaded. Data were presented as mean and standard deviation (SD) values. Results: The results revealed that the stresses transmitted to the abutments teeth and residual ridge by the anterior palatal bar major connector was of lower values than those recorded when the anteroposterior and anterior palatal strap were used. Regarding the adaptation of the major connectors no significant differences occurred before or after loading. Conclusion: It can be concluded that much higher stresses transmitted by the anteroposterior palatal strap and the anterior palatal strap than that transmitted by the anterior palatal bar. Future research should focus on the minimal dimensions for relevant major connectors' adaptation. (3890)