Paediatric Sleep-Disordered Breathing: Pharyngeal Airway and Lymphoid Tissues in Risk Assessment

Background/Objectives: Upper airway constriction and craniofacial structural variation are recognised risk factors for paediatric sleep-disordered breathing (SDB). Population-specific normative cephalometric reference data are lacking, and are needed to characterise these features in paediatric orthodontic patients, especially in Asian populations. This study examined upper airway structure and lymphoid tissue hypertrophy in a large paediatric orthodontic population. The aims of the study were to investigate upper airway differences across skeletal patterns, age, gender, and ancestry groups, establish pharyngeal airway, skeletal, dental, and soft tissue cephalometric dimensions, and determine adenotonsillar hypertrophy prevalence in a large paediatric orthodontic population in Singapore. Methods: Lateral cephalograms of children aged 7–11 years were obtained from a national dental centre, and a retrospective analysis was performed. Standardised cephalometric measurements were used to assess airway, skeletal, dental, and soft tissue parameters, with comparisons across demographic and skeletal groups. Results: A total of 404 children (203 boys, 201 girls; aged 7.04–10.99 years) were included in the final analysis. Thirteen airway variables differed significantly by gender and age, six by antero-posterior, and four by vertical skeletal pattern. One variable (AH-CV) differed between Chinese and non-Chinese children. A form of lymphoid tissue hypertrophy (Ad/Np ≥ 0.5 and/or Tn/Op ≥ 0.5) was present in 92.3% of subjects, comprising combined adenotonsillar hypertrophy (49.5%), isolated tonsillar hypertrophy (36.6%), and isolated adenoid hypertrophy (6.2%). Conclusions: Cephalometric norms for upper airway, skeletal, dental, and soft tissue structures in a 7–11-year-old orthodontic population in Singapore were reported. Adenotonsillar hypertrophy was present in nearly half of the subjects, while isolated tonsillar hypertrophy affected about one-third. Patients who were younger, male, Chinese, Class I, Class II, and had increased mandibular plane angles displayed cephalometric features associated with anatomical risk indicators for SDB. These population-specific cephalometric reference data provide a benchmark for contextualising upper airway and craniofacial measurements in paediatric orthodontic patients, supporting the potential utility of cephalometric assessment to identify children who may benefit from referral for comprehensive SDB evaluation.