Investigating the Effect of Ultrasound on Preventing the Relapse of Severe Crowding : A Quasi- Experimental Clinical Trial

Aim Orthodontic relapse after alignment remains a major clinical concern. This study aimed to evaluate whether adjunctive low-intensity ultrasound could reduce the rate of orthodontic relapse and improve post-treatment stability compared with no intervention.Methods In this quasi-experimental clinical trial, ۳۹ patients (mean age ۱۹.۳ ± ۵.۷ years) with Class I malocclusion and severe dental crowding were enrolled after completion of alignment. Participants were randomly allocated to an ultrasound group (n = ۲۰) or a control group (n = ۱۹). The ultrasound group received therapeutic ultrasound (EME, Pesaro, Italy) at ۱ MHz, ۱۰۰ mW/cm², ۲۰% duty cycle (۲۰۰ μs on/۸۰۰ μs off; ۱۰۰۰ cycles/s), for ۱۰ min/session over ۱۰ sessions. In both groups, archwires were then removed for ۲ months; the control group received no additional intervention. Dental casts were obtained at archwire removal (baseline) and after ۲ months. Outcomes were inter-canine width, inter-molar width, arch length, arch circumference, and modified Little’s irregularity index. Analyses used Chi-square, independent t-test, and paired t-test with .Results All ۳۹ participants were included in the analyses. Over ۲ months, between-group differences in changes of inter-canine width, inter-molar width, arch length, arch circumference, and modified Little’s irregularity index were not statistically significant (P > ۰.۰۵). In both groups, modified Little’s irregularity index differed significantly between the maxilla and mandible (ultrasound: P = ۰.۰۲۵; control: P = ۰.۰۰۲). Within-group analysis showed a significant reduction in mandibular arch circumference in the ultrasound group (P = ۰.۰۰۷) and a significant increase in maxillary arch circumference in the control group (P = ۰.۰۱۸).Conclusion Under the conditions of this trial, low-intensity ultrasound did not reduce orthodontic relapse in the maxilla or mandible during the ۲-month post-alignment period.

کلیدواژه ها:

Orthodontic retention ، Relapse ، Ultrasound