الفهرس 
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Abstract
Purpose: The aim of this study was to compare different techniques (objective versus subjective techniques) to evaluate available restorative space and their effect on strain distributed around two implant retained mandibular overdenture. Materials and Methods: An acrylic resin model representing completely edentulous mandible was constructed. Two dummy implants of 13mm length and 3.7mm diameter were inserted in canine regions, 2mm thickness of simulated mucosa soft liner material was used. Four mandibular edentulous stone casts were duplicated from acrylic resin model. Occlusion rims were constructed and identical size and shape of artificial teeth were arranged.The restorative space was evaluated using objective techniques [ruler (G1) Boley gauge (G2), periodontal probe (G3)] and subjective techniques [silicon matrix index (G4)].Eight strain gauges were placed on 2mm away from the implant at mesial, distal, buccal, and lingual surfaces. Another two strain gauges were place in polished surface opposing to two canines implant area to measure overdenture deformation. Static load of 70N with 0.1mm/min speed was applied to the first molar in bilateral and unilateral loading using universal testing machine. Results: In bilateral loading the lingual side showed higher strain value compared to buccal side while distal side showed higher strain value than mesial side. There was no significant difference between all groups in bilateral loading (P>0.318). Further comparison within groups using Tukey test, there was significant difference in mesial and lingual surfaces (P>0.010 and (P>0.048 respectively) while other surfaces were showed no significant difference in all groups. In unilateral loading condition there was no significant differences in loading side (P>0.198) and in non-loading (P>0.884) in all tested groups. Polished surface showed slightly higher strain value compared to periimplant areas. G4 showed higher strain value than other tested groups. There was no significant differences between all groups in polished surface in right side (P>0.910) and left side (P>0.803). Conclusion: Regardless the evaluation technique of restorative space, the strain transmitted to the polished surface and around implants was nearly the same as there was insignificant difference between groups