Evaluation of Positional Variability in Surface Roughness in Orthodontic Mini‐Implants Using Confocal Microscopy: A Multi‐Manufacturer Comparative Study
Alessandro Antonelli, Till Augustinowitz, Giulia Brunello, Kathrin BeckerABSTRACT
Objective
To compare the surface roughness of orthodontic mini‐implants (OMIs) from seven manufacturers at standardized positions, since positional variability in OMI topography has not been systematically investigated but may influence healing and stability.
Materials and Methods
Seven OMI systems ( n = 5 per system, total n = 35) were analyzed using 3D confocal laser scanning microscopy. Four locations per OMI were assessed (apex, mid, top, neck). Roughness parameters included Sa and Sz (µm), Sdr (%), Str (dimensionless), and Spc (1/mm). Linear mixed‐effects models were fitted for each parameter with Manufacturer and Location as fixed effects and Implant ID as a random intercept. Fixed effects were evaluated by Type III ANOVA; estimated marginal means (EMMs, 95% CIs) and Tukey‐adjusted pairwise contrasts summarized differences.
Results
Manufacturer, location, and their interaction were significant for all parameters ( p < 0.0001). Dentaurum consistently showed the highest mean roughness values, especially at the neck, with an overall average value for Sa ≈ 0.81 µm compared to 0.20–0.39 µm for others, Sz ≈ 9.5 µm (others 2–3 µm), and Sdr ≈ 6%–7% (others ≤ 2%). The mean Spc at the neck reached ≈65,000 1/mm for Dentaurum, while OBS showed markedly lower mean values (< 10,000 1/mm). Ortholox Plus (TigerDental) showed intermediate increases at the neck, while OBS presented the smoothest surfaces, particularly at the neck. Str indicated manufacturer‐specific isotropy: American Orthodontics and Forestadent demonstrated higher Str mean values (≈0.7–1.0) at the top and neck, whereas AbsoAnchor, Dentaurum, DualTop, OBS, and Ortholox Plus showed lower Str.
Conclusions
OMI surface roughness is strongly manufacturer‐ and position‐dependent, with the neck region amplifying inter‐system differences. Selecting OMIs from the market or customizing their design based on anatomical considerations and applied forces may optimize osseointegration and peri‐implant soft tissue health. Adjusting roughness profiles may help reduce implant migration. While long smooth necks might be advantageous in cases of extended transmucosal path.