Volume Assessment of the Effect of Obturators on Facial Form Following Surgery for Head and Neck Cancer Using Stereophotogrammetry

Abstract

Purpose To determine if stereophotogrammetry could be used to determine the effects of obturators on facial contour in relation to the measurement of facial volumes. Materials and Methods Stereophotogrammetry images were recorded from 20 subjects with and without their obturators in place. These were converted into a stereolithographic format and overlaid. Registrations were made using the tissues on the normal areas of the face. Difference images were created, enabling surface areas and volumes to be calculated. To assess repeatability of measurement, 2 readings were recorded on each of 2 separate registrations. Data analysis between the sets of readings used correlation coefficients and paired t‐tests. Coefficients of repeatability were also calculated. Results A comparison of readings for the surface areas showed the method of measurement was repeatable with no significant differences between the 2 repeated readings for registration 1 (p = 0.977, coefficient of repeatability = 101 mm2), registration 2 (p = 0.085, coefficient of repeatability = 106 mm2), and the mean of the two readings for registration 1 compared with registration 2 (p = 0.355, coefficient of repeatability = 103 mm2). Similar results were found for the volume measurements with no significant differences between the repeated readings for registration 1 (p = 0.862, coefficient of repeatability = 229 mm3), registration 2 (p = 0.200, coefficient of repeatability = 209 mm3), and the mean of the 2 readings for registration 1 compared with those for registration 2 (p = 0.131, coefficient of repeatability 339 mm3). There was a statistically significant range of volumes that appeared to have been restored by the obturators (p < 0.0005). Conclusions Stereophotogrammetry is reliable in assessing the effects of obturators on facial form. In the sample of subjects, obturators generally appeared to be effective in supporting facial tissues following surgical resections of the maxilla and therefore contribute in some degree to the restoration of facial appearance.

Effect of obturators on facial form following surgery for head and neck cancer and impact on the perception of appearance

“…These were the same individuals recruited in a previous study [11] appearance, mastication and speech. However, there was variation between the individuals on the location and magnitude of the surgical resection and whether it had been possible to retain any natural maxillary teeth.…”

“…One set of images was recorded with the research participants wearing their maxillary obturator and the second set when they had removed it. Details of how the participants were seated and the accuracy of the system [11] is described by Coward et al (2019).…”

“…An account of how the stereophotogrammetry images were converted and displayed as a colour coded single difference image to show facial changes resulting from wearing an obturator has also been given in detail [11] by Coward et al (2019). This involved loading the two images of the subject with and without the obturator.…”

“…This gave a total of 4 surface area and depth measurements for each participanttwo from the first registration and two from the second. The mean of the four measurements was used [11] as described by Coward et al (2019) to determine the surface area and mean depth differences restored by the obturators.…”

“…However, in a recent piece of work images were recorded of subjects with and without their obturators in place using a stereophotogrammetry technique, and it was possible to show that overlaying and registration of the separate images was consistent and reproducible [11]. This allowed the effect of obturators in restoring facial volume to be measured and therefore provided some objective evidence on their efficacy in providing facial support.…”