Effect of Bonding Height on Force-Moment Generation in Orthodontic Fixed Lingual Retainers: An In Vitro Study

Area of Science:

• Orthodontics
• Biomaterials
• Biomechanical Engineering

Background:

• Fixed lingual retainers are crucial for maintaining orthodontic treatment outcomes.
• Understanding the biomechanical behavior of these retainers under load is essential for clinical success.

Purpose of the Study:

• To investigate the influence of different bonding heights on force and moment generation in orthodontic fixed lingual retainers.
• To compare the biomechanical performance of stainless-steel and nickel-titanium retainers.

Main Methods:

• Three types of lingual retainers (two stainless-steel, one nickel-titanium) were tested in a biomechanical setup.
• Vertical forces and labiolingual moments were measured under a standardized vertical displacement (0.3 mm).
• The effect of bonding height (incisal, middle, gingival thirds) was evaluated.

Main Results:

• Both forces and moments increased with vertical loading.
• Retainer material significantly influenced force and moment generation, with nickel-titanium showing higher values.
• Bonding height did not significantly affect the measured forces and moments.

Conclusions:

• Retainer type exerts a greater influence on force and moment development compared to bonding height.
• Multistranded stainless-steel retainers may exhibit greater susceptibility to deformation under occlusal loading.
• Further research is needed to establish the clinical significance of bonding height in fixed lingual retainers.