The reliability of the Index of Orthodontic Treatment Need over time.

The aim of this investigation was to establish whether the Index of Orthodontic Treatment Need is reliable over time between the ages of 11 and 19 years. It consisted of a longitudinal sample of 314 11- and 15-year-old and 142 19-year-old subjects who had not received orthodontic treatment or extractions. The changes in the aesthetic component (AC) and the dental health component (DHC) of the Index of Orthodontic Treatment Need (IOTN) were measured between the ages of 11 and 19 years. The results suggested that the dental health component of IOTN was reliable over time between the ages of 11-19 years despite temporal changes in the separate occlusal traits that comprise the index. The aesthetic component of IOTN tended to show an improvement over time. The Index of Orthodontic Treatment Need is a reliable index over time when taking into account occlusal changes that are occurring during the 11-19-year age range. The study provides some reassurance to clinicians that an IOTN grading at age 11 years is unlikely to change by the time the patient is 19 years. Refereed Scientific Paper