Following orthodontic treatment, retainers are often a must. However, what biomechanical factors impact their effectiveness? This study investigates the biomechanical behavior of fixed orthodontic retainers, specifically examining how retainer stiffness and tooth resilience affect force transmission and stress distribution. The goal is to understand the mechanics that contribute to retainer bonding failure and improve long-term orthodontic stability. Using a finite element model of the lower jaw, simulations were run with variable retainer bending stiffness and tooth resilience. Applying axial or oblique loads, the study found that force transmission increased with higher tooth resilience and retainer stiffness. Smaller retainer diameters led to uneven stress distribution, creating concentrated stress peaks. Higher overall stress in the adhesive bonding area was associated with stiffer retainers, greater tooth resilience, and oblique load directions. The study suggests that excessively stiff retainers should be avoided, particularly in cases with high tooth resilience. The anterior nasal spine can serve as a reliable reference point for planning the position of the upper incisors. An increase in retainer stiffness and in tooth resilience as well as a more oblique load direction all lead to higher overall stress in the adhesive bonding area associated with a higher risk of retainer bonding failure.
Bioengineering aims to publish innovative research at the intersection of engineering and biology. This study on orthodontic retainers fits the journal's scope well by applying finite element analysis, an engineering technique, to understand a biological problem (tooth movement and retainer stability). The work offers insights relevant to dental professionals and bioengineering researchers.