An objective system for appraising clear aligner treatment difficulty: clear aligner treatment complexity assessment tool

Abstract Background : Recent years has witnessed a remarkable evolution of clear aligner technology and clear aligners are becoming more and more versatile in managing orthodontic patents. The aim of this study was to develop an objective evaluation system for assessing clear-aligner treatment difficulty. Methods : A total of 100 eligible patients were recruited in this study. Based on clinical data (dental models, radiographs and photographs), difficulty levels were evaluated by two experts and regarded as the gold standard. Difficulty scores were determined through an evaluation system encompassing three domains (dental model analysis, radiographic examinations and clinical examinations). The reliability of the evaluation system was examined through analyzing the agreement between difficulty levels and difficulty scores. Moreover, multivariate linear regression test was used to examine the independent effect of each variable (e.g. overbite and crowding) on difficulty level. Results : The results revealed that the assessment of treatment complexity by this objective evaluation system matched perfectly with the gold standard (kappa=0.80). The multivariate regression test revealed that difficulty level was significantly associated with difficulty score (β=0.13, p<0.001), age (β=-0.04, p=0.015<0.01), tooth extraction (β=1.14, p<0.001) and number of difficult tooth movement (β=0.09, p=0.005<0.05). This objective evaluation system elaborated in this study is viable and reliable in appraising clear-aligner treatment difficulty in clinical practice. Conclusions : We suggest practitioners, especially general practitioners, use this evaluation system for appropriate clear-aligner patient selections.