Removable four implant-supported mandibular overdentures rigidly retained with telescopic crowns or milled bars: a 3-year prospective study

Purpose: The present study evaluated implant survival/success rate, peri-implant parameters and prosthodontic maintenance efforts for four implant-supported mandibular overdentures (IOD) rigidly retained on either milled bar or double crowns (telescopic) attachments. Material and methods: In a randomized prospective trial, 51 patients with edentulism received four mandibular interforaminal implants and complete maxillary dentures. For IOD, rigid denture stabilization was chosen randomly selecting 26 patients for milled bars (group I) and 25 patients for double (telescopic) crowns (group II). During a 3-year follow-up period, implant survival/success, peri-implant parameters (marginal bone resorption, pocket depth, plaque-, bleeding-, gingival index [BI and GI], calculus) and prosthodontic maintenance efforts were evaluated and compared between both retention modalities used. Results: Forty-five patients (23 group I, 22 group II) were available for a 3-year follow-up (dropout rate: 11.8%) presenting a high implant survival/success rate (100%). Peri-implant marginal bone resorption, pocket depth as well as BI and GI did not differ for both rigid retention modalities. However, annually higher values for plaque- (NS) and calculus index (P