الفهرس 
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Abstract
Introduction: patients with atrophied edentulous mandible are usually suffering from reduced retention & stability of their dentures. The use of mini dental implants to retain removable and complete dentures is considered among the most common treatment modalities with high efficacy.
Purpose: to evaluate the stress distribution in atrophied mandibular ridges by using four mini implants to retain an over denture with three different mini implant designs and evaluate fatigue behavior using finite element analysis.
Materials and methods: Using solidworks and a patient CBCT data, a digital model for atrophied mandible was constructed. Four mini implants were added to the model in the inter foraminal region. The model was replicated into three models that differ only in implant design. A three implant designs are used (single piece, two pieces with internal connection, two Pieces with external connection).
A 100N (vertical & oblique) bilateral loads were applied through the over denture and Von Mises stresses were analyzed along the implants and surrounding bone. Fatigue test was also done for each simulation using ANSYS (R18.2) software.
Results: The least amount of stress surround implant at compact bone was in model 3 (two pieces with internal connection), but in relation to stress on implant the minimal is in model 1 (single piece).
Conclusion: The least amount of stresses resulting in the compact bone around the implants was recorded in model C (two pieces implant with internal connection). In case of resorbed ridge, using four mini implants with two pieces (internal connection). On the other hand the least amount of stresses delivered to the implant itself was in model.