RESUMEN
BACKGROUND: The aim of this study was to compare the microstrain transmitted to peri-implant tissues of implant-assisted mandibular overdentures 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 middle. 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 A implants were kept solitary with an OT-Equator attachment, while group B implants were kept splinted with a bar associated with two mini-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. A vertical load of 100 N using the universal testing machine was applied unilaterally on the left mesial fossae of the mandibular first molar and bilaterally on the bar attached to the mandibular premolar molar region of the overdentures. Statistical analysis was conducted using IBM SPSS version 28. Normality was checked by using the Shapiro-Wilk test and normality plots. The Mann-Whitney U test was then used to analogize the groups. RESULTS: There was a statistically significant difference between groups A and B upon application of vertical unilateral and bilateral loadings of 100 N, with mean microstrain values of P 0.05. Group A (OT-Equator attachment) showed lower strain values than Group B (OT-Equator bar attachment) upon application of vertical, unilateral, and bilateral loadings of 100 N. CONCLUSIONS: Implant-assisted mandibular overdenture with a solitary attachment is associated with lower microstrain values around the implants after application of unilateral and bilateral vertical loadings of 100 N.