Three-dimensional analysis of aligner gaps and thickness distributions using advanced laboratory-based hard x-ray tomography

Abstract

Physical and mechanical properties of aligners determine the clinical success of orthodontic treatments. A main element of the successful orthodontic tooth movements is the fitting of the aligner’s surface to the backside of the related teeth. The complex human tooth anatomy and the aligner’s production make gaps inevitable. The aim of the tomography study is the morphological assessment of the recently introduced NaturAligner (Bottmedical AG, Basel, Switzerland). Using the advanced micro-CT system (nanotom m, phoenix|xray, Waygate Technologies, Wunstorf, Germany), a series of eight different aligners, placed on the 3D-printed model of the upper jaw, were visualized. Based on these 3D datasets, the gaps between model and aligner were automatically segmented and the thickness distribution of the aligners automatically determined. This quantification, validated by manual inspection, clearly indicated that aligners fitted better the model, when higher process temperatures were applied.