<abstract xmlns="http://www.w3.org/1999/xhtml">

<sec>
<h3>Background</h3>
<p>Few studies have focused on the impact of malocclusion on lip – tooth relationships during smiling and speech.</p>
</sec>
<sec>
<h3>Aim</h3>
<p>To evaluate the impact of different malocclusions on lip – tooth relationships during smiling and speech, using video images.</p>
</sec>
<sec>
<h3>Methods</h3>
<p>One hundred and three subjects with Class I (N = 31), Class II division 1 (N = 26), Class II division 2 (N = 16) and Class III malocclusions (N = 30) were asked to repeat the same sentence and then smile in front of a video camera. Nine frames were extracted from each subject’s video clip: at rest, posed smile, unposed smile and during the pronunciation of the sounds: ‘che’, ‘fa’, ‘se’, ‘chee’, ‘tee’ and ‘mee’. On each frame, up to 10 parameters describing the lip – tooth relationships were measured.</p>
</sec>
<sec>
<h3>Results</h3>
<p>In all frames, there were no statistically significant differences in the upper central incisor display ratios among the malocclusion groups (<italic>p</italic> > 0.05). The buccal corridor ratio in the posed and unposed smiles did not differ significantly among the malocclusions (<italic>p</italic> > 0.05). The most frequently visible last maxillary tooth was the first premolar in the posed smile, and the second premolar in the unposed smile. In each malocclusion group, the upper central incisor display ratio varied significantly among the nine frames and the buccal corridor ratio during the unposed smile was less than the ratio during the posed smile; although this was only significant in the Class II division 2 subjects. The smile arc was similar in all malocclusions.</p>
</sec>
<sec>
<h3>Conclusions</h3>
<p>In each malocclusion the upper central incisor display ratio varied significantly among the nine frames. In each group, the buccal corridor ratio during the unposed smile was less than that during the posed smile, but only the Class II division 2 group was significantly different. The smile arc did not differ among the malocclusions.</p>
</sec>
</abstract>

Background
Few studies have focused on the impact of malocclusion on lip – tooth relationships during smiling and speech.


Aim
To evaluate the impact of different malocclusions on lip – tooth relationships during smiling and speech, using video images.


Methods
One hundred and three subjects with Class I (N = 31), Class II division 1 (N = 26), Class II division 2 (N = 16) and Class III malocclusions (N = 30) were asked to repeat the same sentence and then smile in front of a video camera. Nine frames were extracted from each subject’s video clip: at rest, posed smile, unposed smile and during the pronunciation of the sounds: ‘che’, ‘fa’, ‘se’, ‘chee’, ‘tee’ and ‘mee’. On each frame, up to 10 parameters describing the lip – tooth relationships were measured.


Results
In all frames, there were no statistically significant differences in the upper central incisor display ratios among the malocclusion groups (p > 0.05). The buccal corridor ratio in the posed and unposed smiles did not differ significantly among the malocclusions (p > 0.05). The most frequently visible last maxillary tooth was the first premolar in the posed smile, and the second premolar in the unposed smile. In each malocclusion group, the upper central incisor display ratio varied significantly among the nine frames and the buccal corridor ratio during the unposed smile was less than the ratio during the posed smile; although this was only significant in the Class II division 2 subjects. The smile arc was similar in all malocclusions.


Conclusions
In each malocclusion the upper central incisor display ratio varied significantly among the nine frames. In each group, the buccal corridor ratio during the unposed smile was less than that during the posed smile, but only the Class II division 2 group was significantly different. The smile arc did not differ among the malocclusions.

Lip - tooth relationships during smiling and speech: an evaluation of different malocclusion types

Australasian Orthodontic Journal

This work is licensed under the Creative Commons Attribution 4.0 International License.

Background
Few studies have focused on the impact of malocclusion on lip – tooth relationships during smiling and speech.


Aim
To evaluate the impact of...

Lip - tooth relationships during smiling and speech: an evaluation of different malocclusion types

Published Online: Dec 14, 2023

Page range: 153 - 159

Received: Dec 01, 2009

Accepted: Jun 01, 2010

DOI: https://doi.org/10.2478/aoj-2010-0025

© 2010 Roozbeh Rashed et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.