A 1.5-year randomized controlled trial comparing standard-sized implants and two diameters of mini-implants immediately loaded by mandibular overdenture: radiographic outcomes, short-term survival, and success rate

OBJECTIVE: This study aims to evaluate the marginal bone level changes (MBLC), survival, and success rate of 4 mini-implants (MIs) of two different diameters versus two standard-sized implants (SIs) that were loaded functionally and immediately by a complete mandibular denture. MATERIALS AND METHODS: The study comprised 29 participants with conventional complete dentures; they were randomly allocated into three groups. Group S included 11 participants who received two SIs of 3.75 mm diameter, group M3 included 8 participants who received four MIs of 3 mm diameter, and group M2.5 included 10 participants who received four MIs of 2.5 mm diameter. MBLC was evaluated on each implant's mesial and distal sides after 18 months of loading. A paired t-test and one-way ANOVA were used for intragroup and intergroup comparisons, respectively (P ≤ 0.05). The evaluation of survival and success rates adhered to the criteria established by the International Congress of Oral Implantologists in Pisa (2007). RESULTS: Immediate loading was employed in all cases. No failure occurred in any case. The success rate after 18 months was 90.91% in the S group, 90.63% in the M3 group, and 90% in the M2.5 group. MBLC after 18 months of loading were 0.76 ± 0.62 mm mesially and 0.63 ± 0.90 mm distally in the S group, 1.04 ± 0.72 mm mesially and 1.05 ± 0.84 mm distally in the M3 group, and 1.37 ± 0.73 mm mesially and 1.11 ± 0.68 mm distally in the M2.5 group. CONCLUSION: The SIs group showed better radiographic results and success rates than the MIs groups. As the diameter of the implant decreases, the mean MBLC increases. However, the results of the MIs groups were within acceptable limits. The survival rate was 100% in the three groups.