A 2-center comparison of orthodontist's perceptions of orthodontic treatment difficulty.

The aim of this study was to determine which factors correlate with easy and difficult treatments and to assess the use of the Index of Complexity, Outcome & Need (ICON) as an indicator for treatment difficulty. The study was conducted at 2 centers using a retrospective cross-sectional questionnaire-based design. The participants were specialist orthodontic practitioners in Dresden, Germany and Cardiff, UK. Sixteen specialist orthodontists participated. Each supplied 10 completed cases--5 they regarded as being easy and 5 as being difficult. The specialist orthodontists completed a questionnaire and stated up to 5 reasons why they considered the case easy or difficult. Two examiners were calibrated in the use of the ICON. Logistic regression analysis using a forward conditional systematic model with complexity of case (ie, easy or difficult) as the dependent variable demonstrated statistical significance of the following patient-related factors: pretreatment ICON score, number of appointments, and age. Chi-squared testing demonstrated statistical significance of the following factors: cooperation, extent of overbite, presence of dysfunction, extent of overjet, anchorage, angulation of teeth, presence of crossbite, center-line shift, nonextraction treatment, age at start of treatment, compliance during the course of treatment, oral hygiene level. This study indicates that the main distinguishing factors between easy and difficult cases appear to be pretreatment age, number of appointments, and pretreatment ICON score. However, the odds ratios were not sufficiently high for these factors to be strong predictors of difficulty.