The purpose of this study was to compare the retention of different three retention mechanisms (metal housing with nylon cap, PEEK and retention sil) in ball attachment retained mini-implant mandibular over denture.

Methodology: A total of fifteen completely edentulous male patients were selected from outpatient clinic of the prosthodontics department. the patients were then randomly divided into three groups as six patients per group. Group I: overdentures retained by
with conventional metal housing and nylon caps, Group II: overdentures retained by
with silicone housing retention sil, Group III: overdentures retained by
with PEEK housing.
All patients were scheduled for retention evaluation in a regular follow up visits at time of insertion, 3 months and 6months.
Results:
The results revealed there was a statistical significance increase in retention values in Group III : overdentures retained with PEEK housing when compared to Group I and Group II and the least retention values were recorded in Group II: overdentures retained with silicone housing retention sil at throughout the whole follow up period, While the comparison between different intervals revealed insignificant difference in all groups as P>0.05 (retention insignificantly decreased in all groups) at all intervals.