How Clear Aligners Affect Breathing Problems During Sleep: A Study Comparing Different Treatments in the Same People

This randomized crossover experiment will have each participant serve as their own control i.e., half of the patient will be initially assigned to wear clear passive aligners (control) while other half will wear advancement aligner (intervention). After 3days, they switch, the first half which received clear passive aligners will now receive advancement aligners and vice versa. Randomization will be conducted using online software (randomiser.com), with sequence numbers concealed in envelopes. While blinding the treating clinician and participant is unfeasible, data will be analysed blindly. The research settings shall be craniofacial laboratory of department of orthodontics, faculty of dentistry, University of Otago, where all the screening, recruitment and appliance delivery will take place. Phase one will consist of three sessions: during the first session, volunteers will be screened for eligibility, and those who qualify will provide written informed consent. They will then complete the demographic and sleep health questionnaires, including the STOP BANG Score and their usual time of night sleep . The participant shall also be enquired whether they had a health condition or disability that limited their activities and lasted for over six months (General Health Screening Form). Additionally, the questions will ask if they received a diagnosis of any physical or mental conditions, such as diabetes, heart disease, asthma, depression, or anxiety, within the last five years. Their Body Mass Index (BMI) will be calculated using the standard formula (weight in kg/height in m²). At the second session, a lateral cephalogram shall be taken for sample participants to rule out any enlarged nasal turbinate. Eligible participants will also undergo intraoral scanning and centric occlusion bite registration to fabricate clear passive aligners (Angel Aligner, Shanghai, China). Participants shall be asked to do baseline recordings for snoring frequency and intensity using the home-based Polysomnography (PSG) device, Compumedics® Somfit PRO, during the sleep for two consecutive nights along with sleep stages (EEG) and muscle (EMG) activity of suprahyoid and jaw elevator muscles by using a wearable surface EMG device (MREMG, Dunedin, New Zealand) during the sleep for two consecutive nights. Participants shall be instructed on how to operate the device independently. Additionally, participants shall be instructed to record if they have any consumption of alcohol, seasonal allergy and approximate time they slept on the night of recording as these factors have been found to influence the quality and duration of sleep . At the end of the session, the participants will return all the recording devices for data download. Third session-Randomization will be conducted prior to the second session, after which half of the participants will be assigned to wear clear passive aligners while other half will be assigned to mandibular advancement aligners (MAAs). Participants shall then be instructed to do the sleep recordings from third session onwards similarly as they did for baseline recordings. After a three-day washout period, participants will switch conditions, with those who initially were part of MAA arm will now receive passive aligners, and vice versa. They will then repeat the snoring and EMG recordings for another two nights. At the end of the session, the participants will return all the recording devices for data download. The appliances shall be delivered under the care of registered Specialist Orthodontist with over 30 years of experience.