Purpose: This longitudinal study investigated the relationship between secondary stability and circumferential bone level of narrow diameter implants to retain mandibular overdentures (MO) after 1 and 3 years. Materials and methods: Thirty patients (19 men, 11 women) with a mean age of 67.5 were monitored by the implant stability coefficient (ISQ) and the vertical (VBL) and horizontal (HBL) bone level assessed by CBCT were measured on the 4 implant faces. Two-way ANOVA with repeated measures followed by Sidak’s post-hoc test was used to compare ISQ, VBL and HBL over time and between faces. Results: The linearity and association between ISQ and VBL and HBL were analyzed by Spearmann’s correlation and linear regression tests. ISQ, VBL and HBL did not differ significantly over time (p≥0.05). The comparison between the faces showed that only VBL presented significant differences (p≤0.05) at 1 and 3 years between the following faces: distal and mesial; lingual and mesial; and mesial and buccal. A positive and moderate correlation was observed between ISQ and HBL of the lingual (r=0.502; p<0.01) and mesial (r=0.536; p<0.01) faces at 1 year. The VBL of the mesial face, HBL of the mesial and lingual faces and the overall HBL at 1 year were associated with the ISQ values obtained on these faces. Conclusion: VBL and HBL remained stable across all implant faces over the 3-year follow-up period. Nevertheless, the lingual face demonstrated the greatest VBL, whereas the mesial face exhibited the highest stability, with minimal VBL observed in the third year. Early bone remodeling, particularly during the first year of OM use, may affect implant stability and appears to be associated with HBL changes on the lingual and mesial faces.
