Influence of the clear aligner trimline on incisor tooth movement, and patient experiences during orthodontic treatment

Adult patients (18-50), receiving non-extraction clear aligner treatment will be prospectively recruited to the study. Patients will be asked to wear the aligners for 22 hours per day, on a 9 day interval. The aligners will be custom manufactured in sets of 3, with each set manufactured to either a straight, or scalloped trimline. The clear aligners utilised are TGA approved, commercially available, and the intended use in this project falls within the described scope and intended purpose of the device (ARTG Entry: 320157), (Emergo Asia Pacific Pty Ltd T/a Emergo Australia). The diagnostic and digital treatment planning for the orthodontic tooth movement will be performed for each individual, in line with the therapeutic aims and goals of treatment. Auxiliary features such as bonded tooth attachments may be utilised; these are placed intra-orally at the commencement of treatment by tooth surface preparation with 37% phosphoric acid, bonding agent, and adhesive composite resin. Block randomisation (n=4) will be done to assign participants to the start with the aligner of either the scalloped or straight aligner. After the initial 3 aligners, the subsequent set of 3 will be of the alternate design (e.g. Scalloped -> Straight -> Scalloped), a continuous manner (e.g. No cessation / break between designs). Patients will be consecutively recruited. The straight trimline aligner will serve as the intervention for this trial. Participants will be recalled on a monthly basis for a clinical examination to assess the outcome of tooth movement for the particular set of aligners. This will be done by capturing 3D tooth positional data using a intra-oral scanner. The method is non-invasive and does not exposure participants to any ionising radiation. After the tooth position data is captured, patients will then progress to the first aligner of the subsequent design. Patient comfort and satisfaction with the aligners will be assessed using validated qualify of life measures, including the OHIP-14 Questionnaire, and a visual analogue scale. These questionnaires will be repeated for each aligner design, to assess the patient's acceptance for each set of aligners. The trial will end after a period of 4 months, or 2 sets of each aligner design. Orthodontic treatment will continue after this time point in a continuous manner, until treatment completion. Treatment will be administered by specialist orthodontists, and specialist registrars.