Transfer accuracy of silicone and 3D-printed trays for indirect bonding of orthodontic brackets

Background/Objectives: The ideal positioning of brackets is one of the most time-consuming procedures in orthodontics. The aim of this study was to compare the transfer accuracy between digitally planned bracket positions of additively manufactured trays (ADT) and polyvinyl-siloxane trays (PST). In addition, a comparison between practitioners was made. Materials/Methods: 25 pre-existing digital mandibular dental casts were selected. The position of the brackets (discovery smart, Dentaurum) was planned digitally. Additively manufactured trays were printed and polyvinyl-siloxane trays were produced. Two examiners with different levels of experience placed the brackets on the 25 models once with ADTs and once with PSTs. The bracket position after transfer were compared to the digital plan (GOM Inspect). A linear deviation of < 0.25 mm and angular deviation of < 1° are defined as clinically acceptable. Results A total of 1.400 buccally bonded brackets and tubes were analyzed. In terms of linear deviations, a total of 97,58% of the transferred brackets were within the clinical acceptable values in the PST and 96,75% in the ADT respectively, 90,79% and 96,42% for the angular deviations. No statistically significant difference was found for the transfer of the brackets between the two examiners (p = 0.227), between the accuracy of ADT and PST (p = 0.102) and between the tooth groups (p = 0.299). Conclusions ADT and PST are both effective indirect bonding methods for orthodontic brackets, with transfer accuracy independent of practitioner experience. The transfer accuracy is the highest for the incisors, followed by premolars, canines and molars.