Stern snap angle versus locator attachment: In vitro strain analysis study around two inclined implants used To retain mandibular overdenture

Aim:the aim of this study was to compare two different concepts of attachment in case of two implant retained mandibular overdenture.
Materials and Methods Four experimental acrylic mandibular edentulous model were constructed. In the canine regions of each model, two recesses were prepared in different inclination at 20⁰ to the residual ridge (Group I, buccally inclined) (Group II, lingually inclined), (Group III, mesially inclined), and (Group IV, distally inclined) degree of lingual implant inclination. Two laboratory implants (3.3mm x 11mm) were inserted in each model and covered with 2mm simulated mucosa. Four duplicate mandibular dentures were constructed and connected to the implants using Locator attachments and Stern snap angle attachments. Four linear strain gauges were bonded to the acrylic resin at mesial, distal, buccal and lingual surface of each implant to monitor the strain around the implants on loading and non-loading sided during unilateral and bilateral load application                                                                                                                     
Results:At different sites of inclination (mesial, distal , buccal and lingual) during unilateral and bilateral load application : distally and lingually inclination recorded the highest strain values, and mesially and buccally inclination recorded the lowest values. And at different groups (regardless of inclination, loading side and loading application) the locator attachment recorded the highest strain values, and stern snap angle attachment recorded the lowest values.
Conclusion: During unilateral and bilateral loading regarding inclination the stern snap angle recorded lowest strain than locator attachment. This means that the stern snap angle attachment seems to be more favorable in the stress distribution around inclined implant than a Locator attachment.