Background <p>This study aimed to evaluate linear root–sinus (RS) distances in relation to the severity of transverse maxillary constriction (TMC) severity in adolescents.</p> Methods <p>A retrospective analysis of 135 adolescent CBCT scans was performed, including 90 with TMC (study group) and 45 with normal maxillary width (control group). Maxillary width at the mid-alveolar level of the first molars was measured and compared with mandibular width and age-based norms. Patients were classified into four groups: control, mild, moderate, and severe constriction. The shortest distances between roots of the first premolar (1PM), second premolar (2PM), and roots of the first molar (1&#xa0;M) to the sinus wall were recorded as RS distances. Correlations between TMC severity and RS distances were analyzed.</p> Results <p>No significant differences were found among groups for 1&#xa0;M RS distances. However, 1PM and 2PM RS distances showed significant differences (<i>p</i> &lt; .05), with control groups having greater distances than severe TMC groups. No significant correlation between TMC severity and RS distances was detected (<i>p</i> &gt; .05).</p> Conclusion <p>No statistically significant association was observed between TMC severity and RS proximity in adolescents. However, descriptive trends suggest modest differences in premolar RS distances between constriction extremes, while molar root positions appear relatively stable. These findings are hypothesis-generating and may provide clinically relevant anatomical insights for planning maxillary expansion in adolescent patients.</p>