Objectives: Aim was to assess whether immediate loading (IL) is more effective than delayed loading (DL) for 2-implant bar-retained mandibular overdentures in terms of oral health-related quality of life (OHRQoL) improvement over a period of 24-month.

Methods: In this randomized controlled trial, 32 edentulous patients (mean age: 65.7 ± 10.6 years, 50.0% female) were included. Potential participants had to be unsatisfied with the retention of their current mandibular complete denture and demanded implant treatment for inclusion in the study. OHRQoL was assessed with the 49-item Oral Health Impact Profile (OHIP) at baseline before treatment and 1, 3, 6, 12, and 24 months after implant loading and insertion of implant-retained bars for overdenture support. A mixed-effects model with patients as random effect and an unstructured covariance matrix was developed to address repeated outcome measurement.

Results: Patients' OHRQoL impairment at baseline was substantial indicated by mean OHIP summary score of 45.1 points. OHIP summary scores decreased substantially from baseline to 1-month follow-up to a mean of 33.5 points (P = .020). OHRQoL further improved during study period indicated by OHIP summary score of 25.7 points at 24-month follow-up. Raw treatment effects (IL vs. DL) ranged from -1.2 OHIP points for 12-month follow-up to 5.8 OHIP points for 24-month follow-up. Assuming constant treatment and time effects, treatment effect was small and not statistically significant (-0.7 OHIP points; P= .918).

Conclusion: A 2-implant bar-retained mandibular overdentures substantially improves OHRQoL over a period of at least 24 months. There seems to be no significant effect of implant loading protocol.