Table 1. SPICO criteria for this systematic review.

SPICO: Study design, Participants, Interventions, Comparisons, and Outcomes; OSA: obstructive sleep apnoea; AHI: apnoea-hypopnoea index; SaO2: oxygen saturation

Criteria	Study details
Population	Study participants, aged 4 to 16 years, diagnosed with obstructive sleep apnoea (OSA), may present skeletal malocclusion and respiratory symptoms
Intervention	Orthodontic interventions include rapid maxillary expansion, rapid palatal expansion, personalized oral appliances, mandibular positioning devices, twin block appliances, and comprehensive orthodontic protocols
Comparison	Comparison between control and treatment group
Outcome	Key assessments include AHI, SaO2 levels, polysomnographic variables, skeletal/cephalometric changes, nasal parameters, upper airway morphology, and clinical symptoms
Study design	Prospective and retrospective studies, clinical trials, and observational studies