Clinical outcomes of small-diameter implant-retained overdentures: a retrospective analysis

Aims To analyze the survival rate of small-diameter implant (SDI) retained overdenture and evaluate the implant and attachment complications, as well as prosthetic maintenances, over a follow-up period of ‰¤4.5 years.

Materials and methods Implant placement procedures were performed by dentists at the Advanced General Dentistry Clinic, Faculty of Dentistry, Mahidol University (Thailand) for all patients treated since 2016. Panoramic and periapical radiographs were taken before and after implant placement, to assess bone height around the implant. SDIs of 3 mm diameter and 10 mm length (PW plus®, PWSE, Nakhon Pathom, Thailand) were placed. After implantation for at least 2 months, corresponding housings were incorporated into overdentures using a conventional loading protocol. Assessment of implant survival rate, implant complications, and prosthetic maintenances were conducted as part of a regular implant checkup during the recall period from 2019-2020. Subsequently, patient characteristics, implant survival rate and complications, attachment complications, and prosthetic maintenance procedures were analyzed using descriptive statistics.

Results Patients included in the study (n = 27) had a mean age of 68 years, and received 119 SDIs (41 in maxilla, 78 in mandible) and 38 overdentures (15 complete overdentures, 23 removable partial overdentures). The implant survival rate was 98.3% at mean survival time of 19.4 months (range, 6-55 months). After overdenture delivery, complications related to implant, attachments, and prosthetic maintenances were recorded. One implant complication (peri-implantitis) was recorded among 119 SDIs (0.8%). Attachment (Equator®) complications included: deformation of attachment matrices (34.4%), loss of attachment screw preload (14.0%), wear of metal housing (1.6%), wear of attachment head (0.8%), and dislodgement of attachment screw (0.8%). Prosthetic maintenance procedures comprised occlusal adjustment (72.7%), tissue surface adjustment (6.8%), denture base repair (6.8%), addition of artificial teeth (2.3%), and repair of artificial teeth (2.3%).

Conclusion Our findings suggest that SDI retained overdenture is a successful treatment modality with a high implant survival rate (98.3%) over a 4.5 year follow-up period. Nevertheless, SDI retained overdenture maintenance is crucial.