الفهرس 
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Abstract
This in vitro study was done on a six standard educational edentulous mandibular models. According to the implant number the models were classified into two major groups and according to the mucosal thickness each major group was subdivided into three subgroup as follow:-
Group I:- This group had two telescopic attachment over two implants bilaterally on the canine region, and was subdivided into three subgroup according to mucosal thickness (1, 2, 3 mm) respectively.
Group II:- This group had four telescopic attachment over four implants, two in the canine region and two in the second premolar region, and was subdivided into three subgroup according to mucosal thickness (1, 2, 3 mm) respectively.
Strain gauges were bonded mesially, distally, bucally and lingually around each implant. Strain gauge analysis was used to measure the stress around each implant. Universal loading testing machine was was used to apply loading condition on the overdentures. Stress were measured during loading on the first molar in the right side. Data was collected and statistically analysis.
To evaluate the effect of mucosal thickness on stress distribution around implant retained mandibular overdenture with different distribution of resilient telescopic attachment.
The results of this study revealed that:-
At distal, mesial, buccal and lingual sites of loading side, greatest strain recorded with 1mm thickness, lowest with 3mm thickness. With exception of buccal sites , all sites at non-loading side recorded greater strain with 2mm thickness and lowest strain with 3mm thickness.
For all sites (mesial, distal, buccal and lingual), group I was associated with greater strain than group II at loading site for 1 and 2mm thickness. At non loading side, group I had greater strain than group II for 1mm thickness and group II had greater strain than group I for 2mm thickness. For 3mm thickness no significant differences between groups were detected at both loading and non-loading sides.
For group I, Loading side recorded greater strain than non-loading side at all measurement sites (mesial, distal, buccal and lingual) for all mucosal thickness except mesial and lingual sites at 1mm thickness which record greater strain at non-loading side compared to loading side
For group II, loading side recorded greater strain than non-loading side at all measurement sites (mesial, distal, buccal and lingual) for 1 and 3 mm mucosal thickness. At 2mm thickness, the non loading side recorded more strain than loading side at all measurement sites.
There was a significant differences between measurement sites (distal, mesial, buccal and lingual), for all mucosal thicknesses in both groups at loading and non loading side. At loading side, The distal site recoded the greatest strain while the mesial site recorded the lowest in group I. The lingual site recoded the greatest strain while the buccal site recorded the lowest in group II. There was a greater variation in recorded microstrain between measurement sites at non-loading side.
from results of this study, it can be concluded that:-
1- Increased mucosal thickness may decrease the stress distribution around implants retaining mandibular overdenture.
2- Increasing the number of implants retaining mandibular overdenture with different distribution of resilient telescopic attachments, will decrease the stresses exerted upon each implant.
Recommendation:-
Future clinical studies are recommended to evaluate the soft and hard tissue changes around implants retaining mandibular overdenture with different distribution of resilient telescopic attachment with different mucosal thickness.