Effect of the Number of Mini-Dental Implants on the Bone Height Level in Mandibles Rehabilitated with Mini-Implant-Retained Overdentures: A Cohort Clinical Study.

Purpose: Implant-supported overdentures have shown promise in improving stability and function. The present study aimed to evaluate the bone level around implant-retained overdentures (IODs), comparing rehabilitations with 3 or 4 implants.

Materials and methods: Twenty-four edentulous participants were selected for this study; they were aged 60-70, with adequate rounded ridge, height, and width bone level. The participants were divided into two groups: Group 1, four mini-implants installed in the interforaminal area retaining mandibular overdentures; Group 2, three mini-implants placed in the interforaminal area. Patients underwent surgical procedures, postoperative care, and follow-up evaluations over one year to assess implant stability and bone level changes. Patients were recalled for re-evaluation and adjustments (6, 9, and 12 months) for clinical assessment and analysis of the marginal bone height changes around the implants. The statistical analysis for the comparison used an independent t-test, and between central and peripheral implants, a paired t-test; significance level if p ≤ 0.05.

Results: Comparing the results between central and peripheral implants revealed a non-significant difference in Group 1; therefore, in Group 2, there was only a significant difference after 12 months, in which the peripheral implant bone level was significantly higher than the central implant (p = 0.03). The intergroup evaluation revealed that Group 2 demonstrated significantly higher bone height levels than Group 1 (p = 0.0001). The bone level between central and peripheral implants decreased significantly in every successive interval of all implants except the central implant of Group 1.

Conclusion: The findings suggest distinct differences in bone-level changes between central and peripheral implants and between the two different groups of implants.