Editor's Summary and Q&A

Introduction The aim of the study was to quantify the forces delivered by thermoplastic appliances made of 2 materials with 2 thicknesses to a maxillary central incisor during tipping. Methods Two materials were tested, each in 2 thicknesses: Erkodur (Erkodent Erich Kopp GmbH, Pfalzgrafenweiler, Germany) 1.0 and 0.8 mm, and Biolon (Dreve Dentamid GmbH, Unna, Germany), 1.0 and 0.75 mm. For each material, 5 appliances were produced. To measure the forces applied, an isolated measuring tooth, part of a standardized resin model, was deflected in 0.05° steps from 0° to 0.42° in the vestibular and palatine directions, after placing the respective appliance on the model. For statistical analysis, the force components Fx/tipping and Fz/intrusion at a displacement of ± 0.151 mm from the incisor edge were selected. Means and standard deviations were calculated. The Wilcoxon 2-sample test for group pairings was used. Results The norms for the mean Fx forces ranged from 1.62 (SD, 0.41) to 5.35 N (SD, 0.63). The mean Fz forces were between 0.07 (SD, 0.13) and −2.47 N (SD, 0.34). The highest intrusive forces were measured during vestibular displacement of the measuring tooth. The forces delivered by the thick appliances were overall significantly higher ( P P Conclusions The forces applied were mostly too high when compared with those stated in the literature as ideal. In addition to thickness, the thermoforming process influences the magnitude of the force delivered by a thermoformed appliance.