Comparison of dental plaque reduction after use of electric toothbrushes with and without QLF-D-applied plaque visualization: a 1-week randomized controlled trial

Quantitative light-induced fluorescence-digital (QLF-D)-applied visualisation can be used to detect dental plaque on both human and animal teeth [1‐7]. Red auto-fluorescence of dental plaque reflects endogenous porphyrins associated with products of microbiota metabolism [8, 9]; the fluorescence of porphyrins corresponds to characteristic bands of absorbance between wavelengths of 390 nm and 425 nm, named Soret bands [10, 11]. Although not all dental plaque on the teeth showed red fluorescence [12, 13], old and matured dental plaque does when exposed to light of approximately 400-nm wavelength. Previous studies revealed that the amount of red auto-florescent plaque is closely related to incidence of caries [13‐15] and gingivitis [16].

Electric toothbrushes have rapidly developed as an established alternative to manual tooth brushing over the past three decades [17‐19] and are now widely available; they can be classified into three types: oscillating-rotating, sonic, and ultrasonic. Evidence from multiple studies suggests that oscillating-rotating brushes reduce plaque and gingivitis more than do sonic brushes [20‐22]. Compared with manual toothbrushes, electric toothbrushes removed dental plaque more efficiently among visually impaired school students [23], residents of nursing homes [24], and generally healthy people [20]. Most recently, we developed an oscillating-rotating electric toothbrush with a QLF-D built-in brush head that includes a light source and camera. Users of this toothbrush can observe red-fluorescent dental plaque on the tooth surface while brushing their teeth in real-time via a monitor, such as a tablet or smartphone. The purpose of the current study was to evaluate the efficacy of this system in the reduction of dental plaque relative to the use of an electronic toothbrush in the absence of a monitor among generally healthy participants without clinical gingivitis over the course of a one-week period. The present study is, to the best of our knowledge, the first to report on the use of this novel system comprising an oscillating-rotating electric toothbrush with a QLF-D built-in brush head and monitor.

All participants were non-smokers. Cronbach’s α was 0.825 for SEOH. No adverse events were observed or reported during the study. Differences in sex ratio (monitor use group: man 6, woman 4; monitor non-use group: man: 4, woman 6), age (monitor use group: 21; monitor non-use group: 21) were nonsignificant. GI, PHP, and SEOH scores between the two groups were also nonsignificant. Comparisons of each variable at baseline and follow-up are presented in Table 1. In the monitor-usage group, PHP scores had significantly decreased by the follow-up exam (6 to 16; range, 0–2 and 13–21, respectively; P = 0.029). While in the monitor non-use group, PHP scores did not change significantly between baseline and follow-up (14 to 13; range, 6–20 and 2–26, respectively). There were no significant differences in the GI and SEOH scores between baseline and follow-up regardless of monitor usage.

The present study evaluated the effects of the newly developed electric toothbrush with a QLF-D-applied dental plaque visualisation system on the removal of dental plaque. As this device can aid in visualising dental plaque on tooth surfaces in real time, users of this device can easily observe dental plaque remaining on a tooth surface as they brush via a monitor, for example, on a tablet or smartphone. Our results clearly demonstrate that brushing teeth while looking at a monitor that depicts red-autofluorescent dental plaque improves the efficacy of dental-plaque removal relative to brushing teeth without a monitor.

The usage of the new device did not influence gingivitis status as assessed via GI; nevertheless, this finding suggests that the new device had no harmful impact on the gingiva. Participants in this study were dental students and did not have clinical gingivitis. To evaluate the effect of this device on gingivitis, a trial including patients with clinical gingivitis is required.

Self-efficacy for oral health as assessed by SEOH did not change from baseline to follow-up. A previous study on adolescents attending school demonstrated that an 8-week oral health education program using Qscan, a device based on QLF-D, significantly reduced plaque index and improved oral health knowledge, attitude, and behaviour [29]. Participants in the present study were not provided with any educational information on oral health behaviour and tooth brushing was done individually. Although a period of 1 week might have been too short to modify behaviour or self-efficacy of oral health, our research in context with the aforementioned prior findings suggests that the use of the visualisation system alone might be insufficient to improve oral health-related attitude, behaviours, or self-efficacy.

Due to the camera device, the height of head of the toothbrush was higher than that of a common electric toothbrush. However, the unique shape did not have a harmful effect, as a result of GI.

This study has several limitations. First, the trial period was short. Although the major outcome of the present study was the effect of tooth brushing while visualising red-auto-fluorescent dental plaque on reducing dental plaque, the study’s time course was too brief to observe any effect on gingiva or self-efficacy of oral health. Further research on the therapeutic effects of the new device on gingivitis conducted over a longer period is needed. Second, all participants were young dental students. They had good eyesight and no impediments to necessary arm movements. To confirm the applicability of our findings to other age groups, future experiments should enrol middle- and old-aged participants. In addition, the participants featured good oral health-related self-efficacy for oral hygiene at baseline. Assessments of the monitor system should be performed with participants unrelated to dentistry to observe its effect on oral-health-related behaviour and self-efficacy. Third, to avoid obscuring the visual field on the tooth surface while brushing, a dentifrice without a foaming agent was supplied to the participants. As such liquid-type dentifrices account for only 22% of dentifrice-consumption in Japan, further studies on more commonly used types of dentifrice are required to validate our findings.

Despite the limitations of the present study, tooth brushing while looking at a monitor that depicts red-fluorescent dental plaque with application of a QLF-D system efficiently reduced dental plaque relative to brushing teeth without a monitor.