Natural head position and lower incisor irregularity: Is there a relationship?

Area of Science:

• Orthodontics
• Craniofacial morphology
• Biometrics

Background:

• Natural head position (NHP) is a key indicator of craniofacial posture.
• Lower incisor irregularity is a common orthodontic concern.
• Understanding the relationship between NHP and incisor irregularity may inform treatment planning.

Purpose of the Study:

• To assess the relationship between dynamic natural head position (NHP) measurements and lower incisor irregularity.
• To identify potential gender differences in this relationship.

Main Methods:

• 103 subjects (51 males, 52 females) had plaster models and dynamic NHP measurements taken.
• NHP was measured using an inclinometer and data logger.
• Lower incisor irregularity was quantified using Little's irregularity index.
• Statistical analyses included Mann-Whitney U, Kruskal-Wallis, and Spearman correlation tests.

Main Results:

• Significant gender differences were found in sagittal NHP measurements (p=0.031) and incisor irregularity (p=0.023).
• No significant difference in NHP was observed across different levels of incisor irregularity.
• Males exhibited a significant positive correlation between incisor irregularity and sagittal NHP measurements (r=0.369, p=0.008).
• Females showed no significant correlation between incisor irregularity and NHP measurements.

Conclusions:

• A significant correlation exists between lower incisor irregularity and sagittal NHP measurements in males.
• Females present with a more forwardly inclined NHP compared to males.
• Male subjects tend to have greater lower incisor irregularity than female subjects.