Vijayakumar, N M (2013) Comparative Study of Changes in Pharyngeal Airway Dimension and Hyoid Bone Position following Nonsurgical Orthodontic Treatment in Class I and Class II Subjects. Masters thesis, Tamil Nadu Govt Dental College and Hospital, Chennai.
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Abstract
BACKGROUND: Pharyngeal airway dimensions, narrowing of pharyngeal passage and hyoid bone positions are of interest in orthodontics .It is evident that there exists a mutual correlation between position of the hyoid bone, volume of pharyngeal airway and dentofacial structures. Therefore it is relevant to evaluate the changes in nasopharyngeal airway and hyoid bone position in subjects with moderate dentofacial deformities, who had orthodontic treatment. This retrospective, analytical cephalometric study had been undertaken to investigate correlation in skeletal Class I and skeletal Class II subjects who had undergone non-surgical orthodontic treatment. AIM: The aim of this study was to evaluate and compare the changes in pharyngeal airway dimension and hyoid bone position following non-surgical orthodontic treatment in Class I and Class II dentofacial deformities. MATERIALS AND METHODS: 40 sets (pre & post treatment ) of lateral cephalograms of subjects (20 skeletal Class I & 20 skeletal Class II malocclusion) were analysed. The control group consisting of 20 lateral cephalograms of subjects with normal occlusion and good visibility of hyoid bone were used .All cephalograms were taken in natural head position, with PLANMECA PM 2002 CC PROLINE machine. All the radiographs were scanned with CANON D520 MF scanner and digitized. A Cephalometric analysis software AX CEPH version 2.3.0.74 was used to analyse the radiographs. RESULTS: Pretreatment hypopharynx area was significantly constricted in both Class I and Class II groups with highly significant reduction (p value < 0.001) in Class II groups in comparison with normoocclusion group. In Class I malocclusion group there was a significant decrease in overall upper airway dimensions, with more reduction in glossopharynx and hypopharynx areas following orthodontic treatment with only velopharynx and glossopharynx areas approximating to the values of the normoocclusion group. In Class II malocclusion the glossopharynx and hypopharynx areas were widened significantly, still the hypopharynx area was not widened to the level of normoocclusion group. After treatment the hyoid was retracted postero inferiorly in Class I group and in Class II group the hyoid bone was shifted anterosuperiorly. Still the hyoid position was not approximated to that of normoocclusion group. There was no statistically significant (p value > 0.05) sexual dimorphism in both pharyngeal airway dimensions and hyoid bone positions in all three groups. CONCLUSION: There is a definite difference in pharyngeal airway dimension and hyoid bone position in different malocclusions. It was evident that Non-surgical orthodontic treatment had a significant influence on the pharyngeal airway dimensions and hyoid bone positions in Class I and Class II malocclusion corrections.
| Item Type: | Thesis (Masters) |
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| Uncontrolled Keywords: | Pharyngeal Airway ; Hyoid Bone ; Lateral Cephalograms ; Class I & Class II Malocclusion. |
| Subjects: | DENTAL > Orthodontics and Dentofacial Orthopedics |
| Depositing User: | Subramani R |
| Date Deposited: | 12 Nov 2017 15:14 |
| Last Modified: | 12 Nov 2017 15:14 |
| URI: | http://repository-tnmgrmu.ac.in/id/eprint/3910 |
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