Mandibular implant-supported overdentures: a prospective evaluation of the burden of prosthodontic maintenance with 3 different attachment systems.

PURPOSE A prospective study on mandibular implant-supported overdentures using more than 2 Brånemark implants splinted with multiple round bars evaluated a hypothesis that unnecessary prosthodontic maintenance would result from the contravention of accepted biomechanical principles. MATERIALS AND METHODS A randomized prospective trial on 59 edentulous patients details prosthodontic maintenance and complications of 52 mandibular overdentures (11 unsplinted, 41 splinted) over a 3-year period. RESULTS Prosthodontic maintenance was greater in the first year than in subsequent years, regardless of design. Comparison between the splinted designs with round bars revealed no statistically significant difference with either retentive clip activation or fractures. More than 70% of the retention clips in the 2-implant (single round bar) design needed activation, as compared to 44% of those with the 3-implant (double round bar) or 4-implant (triple round bar) design. Retention clip fracture occurred in 30% of patients with 3 or 4 implants and 16% of those with 2 implants. Relining the overdentures, regardless of design, revealed an excessive maintenance burden in 40% of overdentures. Remaking of overdentures was necessary in 21% of patients. CONCLUSION Multiple round bars splinting 3 or 4 implants can still be a treatment concept in mandibular overdenture treatment. Results from prospective evaluation of this design indicate less prosthodontic maintenance of clip activation but more clip fractures than with 2 implants splinted with single round bars, although not at statistically significant levels.