Discussion
irregularity, crowding, orthodontic
INFLAMMATION, DENTAL PLAQUE, INFLAMMATORY RESPONSE
Our clinical study was performed as a single-blind crossover RCT with a 28-d brushing period to compare the effectiveness of an LED toothbrush with a manual toothbrush in reducing dental plaque and gingival inflammation. A randomized design was used to minimize bias error. The crossover trial allowed us to compare the outcomes from using 2 different types of toothbrushes within the same participants. Because the crossover RCT eliminates the variation among participants, with the same sample size, the results from the 2 interventions can be determined with greater precision, compared with a parallel group trial in which each participant is exposed to only one intervention [We recruited patients who were undergoing fixed orthodontic appliances for more than 1 month because this allowed time for the patients to adapt their brushing skills with the fixed orthodontic appliance, thus, the outcomes were not influenced by the time-dependent acquisition of brushing skills. In addition, to exclude the variation in dental crowding from confounding the results, only participants who had an irregularity index less than 1 mm were recruited. We excluded participants with a higher irregularity index because the crowding may be considerably resolved by the treatment during the period between the first and second interventions, which was 56 days or 2 orthodontic treatment visits. This might affect the outcomes of the interventions and could lead to a sequence effect in the crossover design. Furthermore, dental crowding might limit the LED light exposure to the dental plaque in the crowded areas. The patients performed their assigned brushing methods at home to simulate the normal condition. At baseline, the GI and PI scores were not significantly different between group 1 and 2. Overall, the LED toothbrush use did not significantly reduce the GI and PI scores compared with the manual toothbrush. However, the GI and PI scores decreased in both toothbrush groups. This might be explained by the Hawthorne effect where patients change their behavior because they knew that they would be observed [Previous studies on the effectiveness of an LED toothbrush were conducted in non-orthodontic patients. A study using a blue LED toothbrush (405–420 nm wavelength and 2 mW/cmThe results of our study demonstrated that the LED toothbrush effectively reduced the PI score on the non-bracket side. The reduction in dental plaque was 1.6-fold higher in the LED group, compared with the manual group. In contrast, the opposite outcomes were found on the bracket side. The metal brackets and archwires might limit the LED light exposure to the dental plaque. These results imply that the LED toothbrush successfully reduced dental plaque by inhibiting bacterial viability in the light-accessible area. In addition, the clinical results in the present study revealed that the LED light was less effective compared with the in vitro results. This might also be because when brushing, the participants used toothpaste that might reduce the LED rays so that the oral biofilm was not maximally exposed to the LED light. Perhaps an alternative toothbrush design, where the light is placed outside of the bristle zone might be better because the LED light would not be blocked by the bristles and toothpaste when brushing.Our results revealed that the manual toothbrush performed better than the LED toothbrush in reducing dental plaque in the proximal areas on the bracket side. In accordance with the patients’ comments in our questionnaires, most of the patients who preferred the manual toothbrush complained that the LED toothbrush was larger than their usual toothbrush. Thus, the LED toothbrushes were more difficult to hold and brush in restricted spaces like the proximal areas. Our results also revealed that patients who were compliant were equally compliant with using the manual toothbrush and the LED toothbrush. Additionally, older patients were significantly more compliant with the manual toothbrush than younger patients. In this study, the participants’ age was the only confounder that had the influence over a treatment outcome, which was the change in GI score on the non-bracket side. According to previous studies, the inflammatory response in gingival tissue to dental plaque is higher in older patients [When using aPDT, the mechanism of the bactericidal effect of light is that the bacteria contains a photosensitizer, an agent that absorbs the light [The activity of blue light against The exposure time is one of the most important factors for the bactericidal effect of an LED toothbrush. Previous in vitro studies [Overall, our study adds clinical evidence concerning the effectiveness of the LED toothbrushes, especially for fixed orthodontic patients. However, we tested only the blue-light LED toothbrush, and our in vitro study was performed only on Future clinical studies with different light colors from an LED toothbrush, an exogenous photosensitizer, or new LED toothbrush designs would be beneficial for more solid evidence, especially in orthodontic patients with fixed appliances. Moreover, in vitro investigations using other bacterial strains or more complex biofilms should be performed.