Single versus two-implant mandibular overdentures using early-loaded titanium-zirconium implants with hydrophilic surface and ball attachments: 1-year randomized clinical trial

Objective: This randomized clinical trial aimed to compare the outcomes of the mandibular overdenture retained by one (1-IOD) or two (2-IOD) implants.

Materials and methods: Participants received new complete dentures, were assessed at baseline and randomly assigned to groups. Early loaded single midline implant (1-IOD) or two implants in the canine regions bilaterally (2-IOD). Ball attachments were used for overdenture retention. Post-treatment outcomes (6- and 12-month follow-ups) included patient satisfaction, oral health-related quality of life measures, and chewing function. Data analysis included within- and between-group comparisons, and Generalized Estimating Equations. Both superiority and non-inferiority hypotheses were tested.

Results: Forty-seven participants were included (1-IOD = 23; 2-IOD = 24). Significant improvements in OHIP-Edent were observed after insertion of new dentures and at the 1-year follow-up compared with baseline. No differences were found between the 1- and 2-IOD groups for the OHIP-Edent and QoLFAST scores. Patient satisfaction with the mandibular denture improved significantly from baseline to the 6-month follow-up and remained unaltered until 1 year, with no differences between groups. The magnitudes of treatment effect sizes were moderate to large for patient-reported outcomes. Progressive improvement in chewing function occurred in both groups. Non-inferiority testing based on a 15% non-inferiority margin showed inconclusive results for patient-reported outcomes, whilst chewing function in the 1-IOD group was concluded to be not inferior to the 2-IOD group.

Conclusions: Results support the use of both 1- and 2-IOD. The 1-IOD was also an acceptable alternative to the 2-IOD as a secondary option for the treatment of the edentulous mandible.