Impact of Loading Protocol for Two-Implant-Retained Mandibular Overdentures on OHRQoL

Objectives: Aim of this study was to assess whether immediate loading is more effective than delayed loading for two-implant bar-retained mandibular overdentures in terms of Oral Health-Related Quality of Life (OHRQoL) improvement over a period of 24 months.
Methods: In this randomized controlled trial, a total of 32 edentulous patients (mean age: 65.4±10.8 yrs, 53.1% female) of the Prosthodontic Department of the University Bern, Switzerland, 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. Allocation to either immediate loading (IL) or delayed loading (DL) group was performed using a computer-generated randomization list. Primary study outcome was OHRQoL 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 bar 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 the study period indicated by an 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 5.0 OHIP points (95% confidence interval: -11.3 to 21.2), but not statistically significant.
Conclusions: A two-implant bar-retained mandibular overdentures substantially improves OHRQoL over a period of up to 24 months. However, there seems to be no significant difference between immediate and delayed implant loading.