Analysis of inflammatory complications around implantsupported removable dentures in long-term follow-up: a retrospective study

BACKGROUND: Implantsupported removable dentures are inferior to implant-supported crowns and fixed partial dentures in several aspects; however, in some cases they remain the only prosthetic option. Data on the incidence of inflammatory complications associated with different designs of removable dentures are limited.

AIM: To compare the incidence and types of inflammatory complications in periimplant tissues in edentulous patients using implant-retained overdentures supported by two or four implants with resilient or rigid attachments.

METHODS: A retrospective observational study was conducted. The total number of supporting implants placed under these prostheses was 198. An analysis of the condition of supporting implants (n = 198) and removable dentures (n = 56) fabricated between 2015 and 2025 was performed. Inclusion criteria: complete edentulism, presence of an implantretained overdenture with a bar, and followup data of at least 5 years. According to the design, dentures were classified into those with a bar on four implants with resilient or rigid attachments, and those with a bar on two implants with resilient attachments. The bars were mostly cast from a cobalt-chromium alloy, the denture base was made of polymethyl methacrylate, and the attachments were manufactured by Bredent (Germany). The primary outcome (implant loss rate) and secondary outcomes (mucositis, bone resorption of one-third or one-half of the implant height) were analyzed. The studied parameters were measured during clinical examination and radiographic evaluation.

RESULTS: The study included 56 prostheses supported by 198 implants. The mean service life of implant-retained overdentures, regardless of their design, did not exceed five years. After five years of follow-up, 24.2% of the 198 supporting implants remained. The remaining implants demonstrated bone resorption: 14.6% had resorption of one-half of the implant length and 9.6% had resorption of one-third. All functioning prostheses were supported by four implants: those with resilient attachments accounted for 17.8% of the implants under bar-retained dentures, and those with rigid attachments accounted for 46.7% of the implants under bar-retained dentures. Removable dentures supported by a bar on two implants were no longer present after 5 years due to loss of the supporting implants.

CONCLUSION: This study demonstrates the advantage of overdentures supported by four implants with rigid attachment to the bar in the treatment of complete edentulism. Resilient attachment reduces prosthetic effectiveness in terms of service life and the incidence of inflammatory complications. The functional longevity of overdentures on two implants does not exceed five years. Their service life can be extended through regular followup adjustment of the denture base, attachment components, and implant and denture hygiene.