An investigation of inter-examiner reproducibility in recording malocclusion parameters during orthodontic epidemiologic studies

ABSTRACT

This study assesses inter-examiner reproducibility in recording various malocclusion parameters and Index of Orthodontic Treatment Need (IOTN) grade during patient examination by utilising the kappa statistic. Five previously calibrated orthodontists clinically examined 233 non-orthodontically treated schoolchildren aged 14-17 years for recording various malocclusion parameters. The examination was repeated twice, thirty days apart and precluded the use of study-models or radiographs. Although good inter-examiner reproducibility was observed in recording incisor class, IOTN dental health grade, type of posterior crossbite, and excellent for parameters with absolute criteria like erupted supernumeraries, etc, substantial examiner variation resulted in only fair reproducibility for recording IOTN esthetic category, canine class, overbite category, traumatic overbite and upper centre-line shift of two millimetres or more from the facial midline. Reproducibility for detecting occlusal displacement in the presence of crossbite was poor, and kappa statistic was incalculable for recording openbite and number of upper incisors rotated 30° or more. Kappa was also incalculable for recording IOTN dental health subcategory due to the creation of asymmetric tables caused by rarely chosen subcategory options. Despite prior agreement between previously calibrated examiners on evaluation criteria, detection of certain malocclusion parameters during an epidemiological examination can prove to be challenging. Epidemiological studies that report on prevalence of malocclusion in the population should always report on the kappa reproducibility, especially if the study is carried out by multiple examiners.