Association between adenoid-to-tonsil size ratio and craniofacial characteristics in children with adenotonsillar hypertrophy: a cross-sectional study.

Adenotonsillar hypertrophy (ATH) is a major cause of upper airway obstruction and is associated with specific craniofacial characteristics. However, the craniofacial morphology of children with ATH is controversial. This study aimed to clarify these discrepancies by investigating the association between the adenoid-to-tonsil (A/T) size ratio and craniofacial characteristics in children with ATH, and examining whether age modifies these associations. Children aged 6-10 years were recruited and classified into ATH or no hypertrophy (NH) groups based on lateral cephalograms. For children with ATH, the relative size of the adenoids and tonsils was quantified using the A/T length ratio measured on lateral cephalograms. Based on the median A/T ratio, the ATH group was further divided into two equal-sized groups: a tonsil-dominant (TD) and an adenoid-dominant (AD) group. Craniofacial differences between groups were evaluated. In addition, associations between the A/T ratio and craniofacial morphology were assessed in the ATH cohort. We further examined whether age (6-8 vs. 8-10 years) acted as a moderator of these associations using interaction analyses. A total of 563 children (207 AD, 207 TD, and 149 NH) were included. TD group exhibited greater SNB (B = 0.65, p = 0.028) and Go-Me (B = 0.69, p = 0.038), along with smaller Ar-Go-Me (B = - 0.98, p = 0.029) and Wits (B = - 0.68, p = 0.026) than AD group. In addition, the A/T ratio was positively associated with SGn/FH (B = 0.74, p = 0.048). Moreover, interactions between age and the A/T ratio were observed for MP-SN (B = 2.45, p = 0.044) and Ar-Go-Me (B = 2.86, p = 0.045), and Go-Me (B = - 2.12, p = 0.013). The relative size of the adenoids and tonsils may be associated with craniofacial morphology in children with ATH, with lower A/T ratios tending to be associated with mandibular protrusion and overgrowth, whereas higher ratios appearing to be associated with clockwise mandibular rotation. Notably, age may modify these associations, suggesting the potential importance of timely airway evaluation and management in orthodontic practice.