Soft tissue facial changes in patients 18 years or older after bone-anchored maxillary expansion - a pilot study
Creators: Grewal, Gursimrit K
Publisher: name: University of Alberta Library
Year: 2024

<p>Abstract</p>

<p>Introduction: Maxillary expansion is a therapeutic modality utilized by orthodontists in order to increase the transverse dimension of the maxilla and correct transverse maxillary discrepancies that is commonly utilized in cases with posterior crossbite and maxillary crowding. This thesis will elaborate on how bone-anchored maxillary expansion can affect soft-tissue changes in adult patients. The importance of this thesis is that unlike similar articles we will be utilizing a 3D facial scanner, in conjunction with a CBCT to evaluate the soft tissue changes after maxillary expansion. Linear changes will be measured to determine the changes from pre-maxillary expansion compared to post-maxillary expansion.</p>

<p>Methods: The sample population includes 20 patients and were randomly assigned to the Dresden (Group A) and Moon expander (Group B) groups. The inclusion criteria were as follows: requirement of maxillary expansion treatment for the groups, need of post-expansion orthognathic surgery would be included, full permanent dentition erupted (except 3rd molars),<br>
treatment may involve post-expansion tooth extraction or not, no syndromic characteristics or systemic diseases clinically determined or based on previous records and male and female<br>
between ages 18-30 years.</p>

<p>Each patient in Group A and B will undergo CBCT and 3D facial photographs/scannings at pre- treatment (before maxillary expansion), and after the completion of expansion. These pre- and post-treatment soft tissue measurements will be compared to determine soft tissue changes due to maxillary expansion. To determine measurements from the 3D facial scans, the OrthoInsight software will be used. To determine CBCT landmark measurements, 3D Slicer software will be<br>
used. The landmarks that will be included is: nasal width, mouth width, alar base width, upper philtrum width, nasal tip prominence, nasolabial angle, upper lip thickness, upper lip to E-line, lower lip to E-line, upper lip height, lower lip height, height of nose, and lower anterior facial height (LAFH).</p>

<p>Results: It can be inferred that there are no statistically significant changes from T0 to T1 for any measurements except for endocanthion. Measuring endocanthion on the two imaging<br>
modalities can lack reliability due to its lack of clear demarcation.<br>
The study questioned whether there was an inconsistency in measuring the patients with either the CBCT or 3D facial scanner. The conclusion was that at T0, the following measurements had inconsistencies between the two imaging modalities: height of nose, lower lip to E-line, lower<br>
anterior facial height, height of lower lip, and nasal tip prominence. At T1, the following measurements had inconsistencies: height of vermillion border, lower anterior facial height, mouth width, height of lower lip, nasal tip prominence, and endocanthion.<br>
In addition, there was no statistical significant difference between the Dresden and Moon expander on the changes in the facial soft tissue.</p>

<p>Conclusions: In research question 1, measuring endocanthion on the two imaging modalities can lack reliability due to its lack of clear demarcation. For research question 2, the inconsistencies of these measurements mainly stem from the CBCT field of view, not including the soft tissue menton. Specifically, the lower anterior facial height and height of lower lip. Furthermore, the<br>
absence of the nasion point in select patients, attributed to the CBCT&#39;s field of view limitations, could potentially create a discrepancy in the height of nose measurement. Moreover, the<br>
complexity of visualizing the mouth region in the CBCT scans may impact the precision and reliability of lip-related measurements in the study.<br>
Furthermore, this research study concluded that there is no difference between the Dresden and Moon expander on the soft tissue changes.</p>