Effect of attachment flash on clear aligner force delivery: an in vitro study

Area of Science:

• Orthodontics
• Biomaterials Engineering
• Dental Mechanics

Background:

• Clear aligner (CA) therapy effectiveness is enhanced by composite attachments.
• Attachment placement can lead to resin flash, potentially impacting CA force delivery.
• Understanding the effect of flash on attachment force is crucial for optimizing CA treatment.

Purpose of the Study:

• To investigate the impact of resin flash on the force generated by clear aligner attachments.
• To compare the force delivery of ellipsoidal and rectangular attachments with and without flash.
• To determine if flash significantly affects the mechanical performance of clear aligner attachments.

Main Methods:

• Fabrication of clear aligners using Tristar Trubalance sheets and 3D-printed resin models.
• Bonding of 17 ellipsoidal and 17 rectangular attachments to maxillary right central incisors.
• Quantification of attachment forces using Fuji Prescale pressure film and a calibrated pressure mapping system, both before and after flash removal.

Main Results:

• No statistically significant difference in mean force was observed for either ellipsoidal (p=0.07) or rectangular attachments (p=0.41) in the presence or absence of flash.
• Rectangular attachments generated significantly higher mean forces than ellipsoidal attachments (p<0.001), irrespective of flash.
• The study demonstrated high reliability in force measurements (ICC=0.96).

Conclusions:

• The presence or absence of resin flash around clear aligner attachments does not significantly alter their force generation capabilities.
• Rectangular attachments provide superior force delivery compared to ellipsoidal attachments.
• Clinical implications suggest that minor flash may not compromise clear aligner treatment efficacy related to attachment force.