adverse event, risk, benefit, bimaxillary proclination treatment, randomized trial, posttreatment stability, patients who underwent bimaxillary proclination treatment
Patients with bimaxillary proclination have protruded upper and lower front teeth, which increases lip protrusion.1 It is commonly seen in Afro-Caribbean and Asian individuals. According to a recent study, 31% to 37% of orthodontic patients at one institution in Malaysia have this condition.2 The main aim for treatment of bimaxillary proclination is to refine facial aesthetics for a more flattened profile.3 This is usually done by removing four first premolar teeth and doing further orthodontic work, such as installing braces.
After treatment with braces, a retainer appliance is usually worn to keep teeth aligned. The bimaxillary proclination can return,4 particularly if the amount of tooth realignment was significant.5 Several types of retainers, both permanent and removable, are available to prevent bimaxillary proclination relapse after orthodontic treatment. Bonded retainers (metal wires attached to front teeth) are typically used with patients at risk for relapse,6,7 but these patients may also have a higher risk for caries if not monitored closely since the retainer and teeth need routine cleaning. Removable retainers, commonly made of plastic or acrylic, are easier to clean but need to be worn by a patient to be effective. There is limited evidence to support choice of retainer type to maintain the result of treatment for bimaxillary proclination.
A researcher in Malaysia designed a small study to examine posttreatment stability in patients with bimaxillary proclination. The randomized study involved three groups of nine participants who wore bonded retainers, removable retainers, or both. Participants wore removable retainers part time, at least 8 hours daily, for 12 months. The researcher monitored the participants every 3 months, taking x rays and recording changes in tooth alignment of the upper and lower arch using a standard index of relapse.8 One year after the study period, participants were assessed again for relapse, and participants who relapsed were eligible to receive a replacement retainer. The protocol was registered at Clinicaltrials.gov.
During the first follow up visit at 3 months, the researcher noted a significant opening of space in a participant who was given a bonded retainer. Although the participant was concerned about this gap, the researcher did not consider it attributable to relapse, did not alter the protocol, and continued to recruit other participants. Two other participants with bonded retainers experienced the same issue, but the space was not large enough to qualify as relapse according to the index being used. The study continued to completion without any recorded severe adverse events.
Questions
Do you have any concerns about the scientific validity of the study? If so, how might those concerns relate to ethical principles or values?
Is it justifiable for the researcher to have continued with the study as designed despite participant concerns that were not formally considered serious adverse events? Would it have been advisable to modify the design of the retainers before additional participants were recruited?
The protocol to take an x-ray every 3 months (up to 1 year) after treatment is not a standard practice. Based on ALARA (as low as reasonably achievable) principles, is it justified to expose patients to radiation for this study?
