Classification and characterization of class III malocclusion in Chinese individuals.
BACKGROUND
Class III malocclusion is a maxillofacial disorder that is characterised by a concave profile and can be attributed to both genetic inheritance and environmental factors. It is a clinical challenge due to our limited understanding of its aetiology. Revealing its prototypical diversity will contribute to our sequential exploration of the underlying aetiological information. The objective of this study was to characterize phenotypic variations of Class III malocclusion via a lateral cephalometric analysis in a community of Chinese individuals.


METHODS
One-hundred-and-forty-four individuals (58 males ≥18 and 86 females ≥16) with Class III malocclusion ranging from mild to severe were enrolled in this study. Principal component analysis and cluster analysis were performed using 61 lateral cephalometric measurements.


RESULTS
Six principal components were discovered in the examined population and were responsible for 73.7 % of the variability. Four subtypes were revealed by cluster analysis. Subtype 1 included subjects with mild mandibular prognathism with a steep mandibular plane. Subjects in subtype 2 showed a combination of prognathic mandibular and retrusive maxillary with a flat or normal mandibular plane. Subtype 3 included individuals with purely severe mandibular prognathism and a normal mandibular plane. Individuals in subtype 4 had a mild maxillary deficiency and severe mandibular prognathism with the lowest mandibular plane angle.


CONCLUSIONS
The six principal components extracted among the 61 variables improve our knowledge of lateral cephalometric analysis for diagnoses. We successfully identified four Class III malocclusion subtypes, indicating that cluster analysis could supplement the classification of Class III malocclusion among a Chinese population and may assist in our on-going genetic study.
Department of Orthodontics, School & Hospital of Stomatology, Shanghai Engineering Research Centre of Tooth Restoration and Regeneration, Tongji University, Shanghai, 200072, China.
Cai
C
Li
Department of Orthodontics, School & Hospital of Stomatology, Shanghai Engineering Research Centre of Tooth Restoration and Regeneration, Tongji University, Shanghai, 200072, China.
Ying
Y
Cai
Department of Orthodontics, School & Hospital of Stomatology, Shanghai Engineering Research Centre of Tooth Restoration and Regeneration, Tongji University, Shanghai, 200072, China.
Sihui
S
Chen
Department of Orthodontics, School & Hospital of Stomatology, Shanghai Engineering Research Centre of Tooth Restoration and Regeneration, Tongji University, Shanghai, 200072, China. orthodboy@126.com.
Fengshan
http://orcid.org/0000-0002-7451-7796
F
Chen
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D044466:Asian People / Q000235:genetics* / Q000706:statistics & numerical data; D002508:Cephalometry / Q000379:methods; D016000:Cluster Analysis; D015331:Cohort Studies; D005260:Female; D006785:Hospitals, University; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008313:Malocclusion, Angle Class III / Q000145:classification* / Q000208:ethnology / Q000235:genetics; D015999:Multivariate Analysis; D025341:Principal Component Analysis; D012720:Severity of Illness Index; D055815:Young Adult
Class III malocclusion; Cluster analysis; Mandibular prognathism; Multivariate; Principal component analysis; Subtypes