Objective Isolated Pierre Robin sequence （Ⅰ-PRS） is caused by abnormal mandibular development， and

traditional sparse landmark-based methods are insufficient to capture its complete 3D morphology. This study aimed to use dense correspondence-based 3D geometric morphometrics to precisely quantify mandibular features in Ⅰ-PRS and establish a morphological classification system. Methods This retrospective case-control study included CT data from 200 infants with Ⅰ -PRS and 31 normal infants. Mandibular models were generated through 3D reconstruction， and point-to-point registration was performed using dense correspondence analysis. Principal component analysis （PCA） was used to explore morphological variation within the Ⅰ-PRS group， followed by K-means clustering and canonical variate analysis （CVA） for subtype classification and validation. Results The Ⅰ-PRS mandible showed significant dysmorphology compared to normal controls， with the greatest variations found at the symphysis and mandibular angle. PCA and cluster analysis identified three stable morphotypes： Type I （short body， flat arch）； Type Ⅱ（short ramus， V-shaped narrow arch， with posterior ramus rotation）； and Type ⅡI （high-angle， flat arch）. CVA confirmed the high statistical validity of this subtyping. Conclusion This study successfully quantified the morphological features of the Ⅰ-PRS mandible using dense correspondence analysis and， for the first time， identified and defined three objective morphological subtypes. This classification system provides an important morphological basis for understanding the clinical heterogeneity of Ⅰ-PRS and for guiding precision diagnosis and personalized surgical treatment.

Isolated Pierre Robin sequence, Mandible, 3D geometric morphometrics, Dense correspondence analysis,

Morphological subtyping, Principal component analysis