Assessment of Oropharyngeal Dimensions in Class I Malocclusion with Different Growth Patterns in Iranian Adults

Abstract

Introduction:

Any changes in oropharyngeal dimensions during orthodontic treatment or surgery can not only alter the growth path and pattern but also affect treatment stability. Therefore, awareness of normal dimensions in Class I malocclusions is of great importance. This study aimed to investigate oropharyngeal dimensions in Class I malocclusions with different growth patterns.

 Materials:

In this descriptive study, 80 adult participants (12 females and 14 males in the Low Angle group, 20 females and 7 males in the Normal Angle group, and 18 females and 7 males in the High Angle group) were selected from the patients who visited the orthodontic department of the Faculty of Dentistry, Islamic Azad University, during 2021-2022. All participants had Class I malocclusion, were within the age range of 18-25 years, had normal respiration, and had no history of orthodontic treatment, orthopedic surgery, or craniofacial anomalies. Lateral cephalometric radiographs were taken for all participants. A total of 37 measurements (12 measurements for evaluating the oropharyngeal airway pathway and 25 measurements for evaluating craniofacial morphology) were assessed. The differences between the groups were statistically evaluated using a one-way ANOVA test.

Results:

According to the ANOVA analysis, 21 out of 25 measurements related to craniofacial morphology showed statistically significant differences among different growth patterns. Among the parameters related to oropharyngeal morphology, the MPT (mouth-throat passage) was found to be greater in the Normal Angle group compared to the High Angle group (P=0.05), and the C3H parameter was greater in the Normal Angle group compared to the Low Angle group (P=0.04). The SPAS (superior airway width) was reported to be lower in the High Angle group compared to the Normal Angle group (P=0.08). These parameters did not show significant differences among the other groups. Additionally, no significant differences were found in tongue dimensions (TGH, TGL), middle and lower airway width (IAS, MAS), and vertical airway height (VAL) among the three groups.

Conclusion:

In samples with Class I malocclusion, different vertical growth patterns influence soft palate thickness, the position of the hyoid bone relative to the third cervical vertebra, and possibly the width of the superior airway passage.