The influence of different Cheek and lip retractors and emissivity on intraoral infrared thermography.

Abstract

To assess the influence of two conventional and one adapted cheek and lip retractors and three emissivity setting values on intraoral infrared thermography (IT) temperature values. The sample was composed by 50 volunteers. Three cheek and lip retractors were tested: Group 1 - flex retractor (FR); Group 2 - FR adapted with Styrofoam; Group 3 - U-type retractor (UR) for cheek and lip. All thermograms were acquired using FLIR T650 infrared camera. A set of three thermograms in frontal norm were acquired for each lip and cheek retractor at 0.91, 0.96 and 0.98Ɛ, with an interval of 15 minutes between each set of images to avoid thermal interference. All images were assessed by two observers. The ROIs' mean temperature of the four upper incisors were recorded. Two-way ANOVA and Sidak posttest were used for data assessment with a significance level of 5%. Group 3 showed higher mean temperature than groups 1 and 2 at all emissivity settings for all assessed teeth (p < 0.05). 0.91Ɛ showed higher temperature than 0.96Ɛ and 0.98Ɛ for all assessed variables (p < 0.01). Contralateral teeth assessed using Group 3 at 0.91Ɛ showed statistical differences between each other (p < 0.05). No statistical difference was observed between contralateral teeth assessed using Group 1 and 2 at 0.96 and 0.98Ɛ (p > 0.05). The choice of cheek and lip retractor and emissivity setting can interfere on intraoral IT temperature values. U-type cheek and lip retractor and 0.91Ɛ setting should not be used for IT image acquisition when assessing dental tissues.