Purpose: This study aimed to evaluate Peri-implant strain with locator and bar attachment during dislodging of maxillary implant overdenture
Materials and methods: Four implants were inserted in completely edentulous acrylic maxillary model in canine and premolar areas. Experimental maxillary overdentures with 4 metal hooks were constructed and connected the implants with bar attachments (group I) or locator attachment (group 2). Two strain gauges were bonded at buccal and palatal surface of each implant. Micro strains were measured at buccal and palatal surface of canine and premolar implants during the vertical dislodging of the overdenture. Dislodging was made by chains connected at one end to the metal hooks and to a universal testing machine at the other end.
Results: For canine and premolar implants, locator attachment showed significant higher microstrain values than bar attachments at buccal and palatal gauge positions. For bar group, no difference between buccal and palatal strain gauge positions was detected. However, for locator attachments, buccal strain gauges demonstrated significant higher strain than palatal gauges. For buccal and palatal strain gauges, canine implants showed higher strains than premolar implants for both groups
Conclusion: Within the limitation of this in vitro study, could be concluded that bar attachments may be recommended to retain maxillary implant overdentures than locator attachments in terms of reduced peri-implant stresses that occur during the denture dislodgment which may lead to increased bone resorption around the implants.