Multibraided Fixed Retainers with Different Diameters after Magnetic Resonance Imaging (MRI): In Vitro Study...

Area of Science:

• Dental materials science
• Biomaterials engineering
• Medical imaging physics

Background:

• Orthodontic fixed retainers are commonly used to maintain tooth alignment post-treatment.
• Patients with fixed retainers may require magnetic resonance imaging (MRI) for diagnostic purposes.
• Concerns exist regarding potential heating and compromised bonding of metallic orthodontic appliances during MRI.

Purpose of the Study:

• To evaluate the in vitro heating effects and bonding efficacy of stainless steel multibraided fixed retainers under 1.5-tesla (T) and 3-T MRI conditions.
• To determine if different wire diameters of the retainers influence heating or bonding strength after MRI exposure.

Main Methods:

• 180 human mandibular incisors were used to create 45 four-tooth specimens.
• Handmade multibraided fixed retainers (0.008″, 0.010″, 0.012″ wire diameters) were bonded to the incisors.
• Specimens were divided into nine groups: three for 1.5 T MRI, three for 3 T MRI, and three controls (no MRI).
• Temperature changes, shear bond strength (SBS), and adhesive remnant index (ARI) were measured before and after MRI exposure.

Main Results:

• No significant temperature increase was observed after 1.5 T MRI exposure (p > 0.05).
• A significant temperature increase was noted in all 3 T MRI groups (p < 0.05), but changes were clinically irrelevant (< 1 °C).
• No significant differences in temperature variations were found across different wire diameters (p > 0.05).

Conclusions:

• No significant changes in shear bond strength (SBS) or adhesive remnant index (ARI) were observed after MRI exposure (p > 0.05).
• The tested stainless steel multibraided fixed retainers demonstrated negligible overheating and maintained bonding integrity.
• These findings indicate that the tested fixed retainers are safe for patients undergoing 1.5 T and 3 T MRI examinations.