Artefact of fixed orthodontic auxiliary appliance in craniofacial CT image

ABSTRACT Purpose. The study aimed to evaluate the artefacts from different types of fixed orthodontic auxiliary appliance. Methodology. This is an in-vitro cross-sectional study. Six different types of the fixed auxiliary appliance were placed consecutively into a cadaveric skull head in combination with orthodontic brackets. All scans were performed by a single operator using the same CT machine followed by a standard scanning protocol. Artefact intensity for all data sets was quantified by calculating the standard deviation (SD) of the grey values within the dataset by following a standard method. All the axial slices were divided into two anatomical zones according to the Frankfort horizontal (FH) plane. The zone-A covered the axial slices which were above the FH plane and zone B consist of axial slices which were below the FH plane One-way ANOVA Tamhane test was used for the data analysis. The level of significance (p) was set at 0.05. Result. The mean artefact score of CT images with the fixed orthodontic auxiliary appliances was significantly higher than the control images at zone B. In addition, there was no significant difference (p = 0.061) observed between the CT images with fixed orthodontic auxiliary appliances and control images within the zone A. Conclusion. Fixed orthodontic auxiliary appliances produced a significant amount of noise below the FH plane and removal of this appliance before a CT scan will improve the image quality significantly within the area.