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Dental age-based assessment of retromolar morphology in skeletal Class III patients: Implications for mandibular
Thuy-Trang Thi Ho1, Tu Manh Nguyen2, Loc Minh Lu1
1Department of Orthodontics, Faculty of Dentistry, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam.
Background/Purpose:
In skeletal Class III malocclusion, evaluation of mandibular third molar development is clinically important for orthodontic treatment planning, particularly in relation to posterior space conditions. This study aimed to assess the association between dental age of mandibular third molars and retromolar morphological characteristics in skeletal Class III patients.
Materials And Methods:
This retrospective cross-sectional study included panoramic radiographs from 157 patients diagnosed with skeletal Class III malocclusion based on clinical examination and lateral cephalometric analysis. Mandibular third molar development was evaluated using Demirjian mineralization stages (D-H), representing stages from crown completion to root maturation. Retromolar morphology was evaluated using retromolar space (RMS), the RMS-to-crown width ratio (Ganss ratio), and the mesiodistal angulation between the second and third molars (Beta angle). Correlations between dental age and these morphological parameters were analyzed.
Results:
As dental age progressed, RMS increased from 5.59 mm to 9.18 mm and the Ganss ratio from 0.45 to 0.70, whereas the Beta angle decreased from 35.82° to 24.80°. Dental age showed moderate positive associations with RMS and the Ganss ratio (P < 0.001), but no significant association with the Beta angle (P = 0.479). These findings indicate coordinated changes between third molar development and retromolar morphology in skeletal Class III patients.
Conclusion:
Dental age-related changes in retromolar morphology may provide useful radiographic information for describing posterior space conditions in skeletal Class III patients.
