A Comparative Study to Evaluate Microstrain of Low-profile Attachment Associated with and Without Bar Connection in Implant Assisted Mandibular Overdenture (In Vitro Study)

Abstract

Abstract Background: Edentulous patients can have substantial difficulties using their conventional complete dentures due to a lack of retention, support, and stability and the related compromise in chewing ability. Endosseous implants have been shown to be a valuable rehabilitation for completely edentulous patients. Various attachment systems can be used for retaining mandibular overdentures such as bar, ball and socket, magnet, and locator. This study was done to compare the microstrain transmitted to peri-implant tissues of implant-assisted mandibular overdenture using two different low profile attachment designs; OT- Equator attachment with and without bar attachment. Materials and Methods: A completely edentulous epoxy resin mandibular model was used, in which two parallel dental implants were inserted at the canine region bilaterally and one in the midline. Sixteen identical complete edentulous mandibular overdentures were fabricated following conventional, standardized techniques and were divided equally between two groups according to the design and placement of the OT-Equator. Group I were kept solitary with OT- Equator attachment loaded on three implants, while group II were splinted of three implants with a bar associated with 2 OT- Equator attachments in-between. Sixteen identical mandibular complete overdentures were constructed to which attachments were picked up. The difference in stress distribution was measured using strain gauges and compared between the two studied groups. Vertical load of 100 N using the universal testing machine were applied unilaterally on the left mesial fossae of mandibular first molar and bilaterally on bar attached in mandibular premolar molar region of the overdentures. Results: Results revealed a statistically significant difference between groups I and II upon application of vertical bilateral and unilateral loading of 100 N, with mean microstrain values of P 0.05. Group I (OT-Equator attachment) showed lower strain values than Group II (OT-Equator bar attachment) upon application of vertical, unilateral, and bilateral loading of 100 N. There was a positive correlation between the diameter of the attachment and the magnitude of stresses that are transferred to the cortical bone. Conclusions: There was statistically significant difference in microstrain values at the peri implant tissues between OT-Equator attachment group and OT-Equator bar attachment group for implant assisted mandibular overdenture upon application of unilateral and bilateral vertical loading 100 N, Solitary OT-Equator attachment showed less microstrain values with favorable stress distribution when compared to OT-Equator bar attachment for implant-assisted mandibular overdenture.