Effects of clear aligner-based expansion screw and nickel-titanium palatal expander on airway dimensions and sleep parameters in unilateral cleft lip and palate patients: a randomized clinical trial.

Abstract

Purpose: This study compared the outcomes of clear aligner-based expansion screw (CAE) and nickel-titanium palatal expanders in mixed dentition patients with elevated sleep questionnaire scores.

Methods: A randomized clinical trial was conducted on 24 UCLP patients presenting with transverse maxillary deficiency and elevated sleep questionnaire scores. Participants were allocated to treatment with either CAE or NiTi palatal expander. Cone-beam computed tomography (CBCT) and polysomnography (PSG) were performed before and after expansion. Changes in airway volume and sleep parameters were assessed. Correlation analyses were conducted to determine associations between expansion characteristics and airway or PSG outcomes.

Results: Pre- and post-expansion Cone-Beam Computed Tomography (CBCT) and polysomnography (PSG) showed that both modalities significantly improved pharyngeal airway volume and sleep parameters. Both groups demonstrated significant improvements in pharyngeal airway volume and PSG parameters. CBCT-based transverse measurements confirmed significant increases in intercanine width, intermolar width, basal bone width, and buccal tipping of molar in both groups, with group1 showing significantly greater gains in intercanine and intermolar width than group 2. Correlation analysis revealed statistically significant positive correlations between the change in intercanine width and increases in nasopharyngeal, oropharyngeal, and total pharyngeal airway volume, and between the change in intermolar width and oropharyngeal airway volume; no significant correlations were observed for J-J' width, basal bone width, or buccal tipping of molar with airway or PSG parameters. A statistically significant negative correlation was observed between skeletal expansion and Δ minimum SpO₂ in the NiTi group.

Conclusion: Both CAE and NiTi palatal expanders significantly improved airway dimensions and sleep parameters in UCLP patients. Anterior transverse widening (intercanine and intermolar width) correlated positively with airway volume gains, whereas basal skeletal widening (J-J' width, basal bone width) and molar inclination did not, suggesting that the overall expansion effect rather than its mechanistic subtype may be the primary driver of functional benefit. Both appliances demonstrated comparable clinical effectiveness.