Retention Evaluation of Implant-Supported Palateless Maxillary Overdentures Retained by PEEK Telescopic Attachment

Background: Retention and stabilization of implant-supported overdenture is associated with more patient satisfaction, chewing capability, and oral health-related quality of life. There are a variety of implant retention systems which can be utilized to retain an implant overdenture. Telescopic attachments provide excellent retention resulting from friction. Objective: This study evaluates the retention force and fatigue resistance of ready-made polyether ether ketone (PEEK) telescopic attachment in different numbers and positions of dental implants in palateless maxillary overdenture. Method: Five edentulous maxillary models were fabricated from cold-cure poly methyl methacrylate resin. The study models were divided into two groups; the first group (3-implant supported overdenture) and the second group (4-implant supported overdenture). Each group is subdivided into subgroups according to the different implant positions. One palateless maxillary denture was constructed over each model. Ready-made PEEK telescope attachments correspond to implant abutments embedded in the inner surface of these overdentures. Initial anterior, posterior, and central retention values of overdentures were estimated and compared with the retention after 540 cycles of insertion and removal using a digital force gauge. One-way ANOVA testing was used to compare the means of the models of group one, an Independent sample t-test was used to compare the means of the models of group two, and a comparison of retention value between the groups and Paired sample t-test was applied for determining the difference between initial and secondary retention value (p<0.05). Results: The anterior retention value was significantly decreased when the dental implants were placed distally while the posterior and central retention values were significantly increased. Also, retention value increased as implant number increased; the lowest mean retention values were recorded with Group one and the highest values were with Group two. The final retention value was significantly decreased after 540 times insertion and removal. However, the values of secondary retention are still larger than the minimum retention value that was reported (5–7 N) to achieve sufficient patient satisfaction. Conclusion: The implant location and number affect the retention value of palateless maxillary overdenture. Continuous insertion and removal of the prosthesis for daily hygiene practice lead to decreases in retention values.