Student Number : 9000040F -
M Dentistry research report -
Faculty of Health Sciences / This study assessed the sagittal soft-tissue changes of the lower lip and chin area in 22 patients
subsequent to mandibular autorotation following surgical vertical impaction of the maxilla. A
subgroup of six patients in addition had undergone advancement genioplasty procedures.
Lateral cephalometric radiographs were taken immediately prior to surgery and on average 15
months following surgery. Sixteen cephalometric landmarks were identified on each
radiograph and these were digitized using a Kontron Videoplan Image Analysis System to
enable differences reflecting changes to be assessed.
The comparison between those cases that had had maxillary elevation only and the six cases
that had received additional advancement genioplasty procedures revealed statistically
significant differences in relation to the proportional changes in the chin area. Therefore, when
studying the soft-tissue chin changes following mandibular autorotation, these six patients
were excluded from the sample. It was found that there was no significant difference in the
lower lip response between the two groups and therefore when studying the lower lip changes,
the two groups could be pooled.
The soft-tissue changes in the chin area showed statistically and clinically significant
correlations. In the horizontal plane, a ratio of 0.9:1 was found for the changes between sulcus
inferior and point B, between soft-tissue pogonion and hard-tissue pogonion, and between
soft-tissue gnathion and hard-tissue gnathion. In the vertical dimension, soft-tissue gnathion followed hard-tissue gnathion in a ratio of 0.9:1, whereas soft-tissue menton followed hardtissue
menton in a ratio of 1:1.
In the study of the lower lip response, a significant correlation with a ratio of 1:1 existed for
the horizontal change in the lower lip as measured at labrale inferius relative to both lower
incisor tip and lower incisor anterius. In the vertical dimension, stomion inferius followed
lower incisor anterius in a ratio of 1.3:1, while labrale inferius followed lower incisor anterius
in a ratio of 1.5:1.
Multiple regression analyses revealed that presurgical tissue thickness exerted no influence
upon the strength of the correlations between changes expressed at corresponding soft- and
hard-tissue landmarks located in the lower lip and soft-tissue chin area.
Based on the findings of this study, it is suggested that the soft-tissue to hard-tissue ratios may
be applied to prediction tracings with enhanced confidence. As a result, the tracings will
reflect a more accurate prediction of the lower lip and soft-tissue chin positions following
autorotation of the mandible.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/1875 |
| Date | 17 November 2006 |
| Creators | Ksiezycki-Ostoya, Beata Katarzyna |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 112988 bytes, 923220 bytes, 70658 bytes, 53612 bytes, 46332 bytes, 237329 bytes, 824368 bytes, 41619 bytes, 50335 bytes, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf, application/pdf |
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