Ashraf Badawy Ibrahim*, Mohamed Maamoun El-Sheikh**, Mohamed Nabeel M. El-gendy***.
^{* Dentist in ministry of health and population in Egypt.
** Professor of Prosthodontic and Vice Dean of Community Service and Environmental Development, Faculty of Dentistry, Tanta.
*** Lecturer of Prosthodontics, Prosthodontic Department, Faculty of Dentistry, Tanta.}.

Abstract:
Aim of the work: The aim of this in-vitro study was to compare between stress distribution around straight and tilted posterior dental implant with different lengths under removable partial denture using electrical strain gauge.
 Methods: Four models representing mandibular unilateral distal extension edentulous area in right side were fabricated from epoxy resin and divided into four groups according to the length and angulation of the implant: Group (A), Single vertical straight implant 8mm length was placed at the second molar region. For Group (B): Single vertical straight implant 10mm length was placed at the second molar region. For Group (C): Single 30o mesially tilted implant 8mm length was placed at the second molar region. For Group (D): Single 30o mesially tilted implant 10mm length was placed at the second molar region. Locator abutment was screwed to the implant and removable partial denture was fabricated for every group. 100 N vertical and 65 N oblique static loads were applied at the central fossa of the second molar artificial tooth in the prosthesis. Strain gauge technology was used to measure the microstrains around peri-implant area. Data were collected, tabulated and statistically analyzed using one-way ANOVA and LSD tests.
 Results: The results revealed that the microstrain with vertical and oblique static loads in group (A) similar to group (C) and in group (B) similar to group (D) (with variation in implant angulation but constant length), but the microstrain with vertical and oblique static loads in group (A) more than group (B) and in group (C) more than group (D) (with variation in implant length but constant angulation). Conclusions: The microstrain distribution was quite similar for both vertical and tilted implants but in increased implant length can help reduce the microstrain.
Keywords: Locator attachment, Microstrain, Strain gauge, Tilted Implant.