This study was a parallel-group, randomized, controlled, single-blind clinical trial and was conducted in the Department of Advanced General Dentistry between January 2021 and May 2022. In this trial, the data analysts were blinded to the group assignments to ensure unbiased statistical analysis. This study was registered with the Clinical Research Information Service and is reported following the CONSORT-EHEALTH (Consolidated Standards of Reporting Trials of Electronic and Mobile Health Applications and Online Telehealth) checklist (Multimedia Appendix 1) [10].

Participants were recruited via offline recruitment strategies. The study recruited participants through notices posted at Yonsei University Dental Hospital and within Yonsei University. Interested individuals underwent a screening process, including a review of medical records and an oral examination, to confirm eligibility based on the study criteria. The inclusion criteria were as follows: patients (1) with good general health and who were aged >19 years; (2) who had 24 or more teeth, including implants or bridges; and (3) who used a smartphone. The exclusion criteria were as follows: patients (1) with moderate to severe periodontitis [11]; (2) with orthodontic devices in the oral cavity; (3) with removable dentures; (4) with salivary gland–related diseases; (5) with halitosis caused by systemic diseases (eg, digestive system–related diseases, liver-related diseases, kidney-related diseases, medication-related osteonecrosis of the jaw); (6) who had received head and neck radiation therapy; (7) who were pregnant or lactating; (8) who lacked communication skills (including disabled individuals); and (9) whose work was related to dentistry or medicine

The sample size was 150 participants, divided into 3 groups of 50 each. The sample size was calculated using G-Power 3.1.9.2, with an effect size of 0.3, significance level of .05, and statistical power of 85%, considering a dropout rate of 15% [12]. The study participants were randomly divided into 3 groups (ORT, ITT, and MT) using block randomization (block size: 5) via software (Excel, Microsoft Corp) before the start of the study. Participants identified as eligible were randomized using a computerized randomization tool by 2 independent researchers who were not involved in the rest of the study. Before participating in the study, participants who met the inclusion criteria completed a self-reported questionnaire.

In this study, an MT and 2 types of smart toothbrushes were used: (1) ITT and (2) ORT (Figure 1).

The ITT (Mombrush; XiuSolution) was chosen as the primary intervention due to its advanced telemonitoring capabilities. This toothbrush connects to the Mombrush ProCare smartphone app via Bluetooth, allowing for real-time tracking of brushing behavior, including frequency, duration, and technique.

After installing the Mombrush ProCare app on the participants’ smartphones, they brushed according to the video guide on how to brush with the rolling method (Multimedia Appendix 2). Participants in the ITT group were also registered in the Mombrush advisor application, which allowed the researcher to check the records of continuous brushing habits, regular brushing habits, brushing balance, and brushing areas in real time. These brushing records were stored on a cloud server and reviewed weekly by dental professionals, who provided personalized feedback on regular brushing habits, brushing balance, and brushing zones.

The ORT with a CrossAction brush head (Oral-B Genius 8000; Procter & Gamble), which was included as a comparator, features smartphone-guided brushing without telemonitoring capabilities. It represents an advanced electric toothbrush widely used in practice, enabling a direct comparison with the telemonitoring approach.

Selected participants were instructed to install the Oral-B app and connect the electric toothbrush to their smartphone via Bluetooth (Multimedia Appendix 3). Participants brushed in Clean mode using the coaching function provided by the app. Since this app was an on-device app, the researcher could not check the brushing records in real time, so the researcher received a screenshot of the brushing records once a week and provided feedback.

The American Dental Association reference MT (PRO-SYS Sensitive Toothbrush; Benco Dental) was selected for the control group and serves as the standard brushing method. This allowed for the evaluation of the added benefits provided by digital and telemonitoring interventions.

The MT group recorded the number of brushing strokes in a brushing diary after receiving brushing instruction. Participants in the MT group sent their brushing diaries to the researcher once a week. The diaries were reviewed, and a professional provided feedback.

All participants were instructed to brush their teeth with the products distributed at least twice daily during the study period and to abandon other oral hygiene aids, such as dental floss, interdental brushes, and mouthwashes. All groups were provided with standard sodium fluoride toothpaste (1450 ppm NaF) for use with their assigned toothbrush.

All statistical analyses were performed using SPSS (version 25; IBM Corp). Data were tested for normality using the Kolmogorov Smirnov test. One-way ANOVA and chi-square tests were used to analyze the demographics and questionnaire responses of the study participants. Independent-sample t tests were used to compare changes in brushing habits by group. SHS, QHI, and volatile sulfur compounds were analyzed using repeated measures ANOVA with Bonferroni multiple comparison tests. Changes in microbiota within groups were analyzed using a paired-samples t test. All statistical analyses were 2-tailed, and the statistical significance level was set at P<.05.

The Institutional Review Board (IRB) of the Dental Hospital at Yonsei University reviewed and approved the study protocol prior to the trial in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments (IRB number: 2-2020-0032). All participants completed a written consent form and were given information regarding the study. All data were anonymized to ensure participant confidentiality.

A total of 161 participants completed the screening; 11 of the screened participants did not meet the inclusion criteria, resulting in 150 participants who completed the study (Figure 2). The general characteristics of the participants are presented in Table 1. The average age of the participants was 31.90 (SD 7.34) years, and 61 (61/150, 40.7%) men and 89 (89/150, 59.3%) women were included. Regarding their academic qualifications, a bachelor’s degree was the most common academic qualification in all groups. There were no statistically significant differences in general characteristics among the 3 groups. Similarly, there were no statistically significant differences between the groups in the self-reported questionnaire on current oral care habits and awareness of telemonitoring toothbrushes at the beginning of the study.

The mean SHS increased over time in the MT group (3.16, SD 4.86 to 5.66, SD 5.20) and decreased at the 1-month recall in the ORT and ITT groups (1.53, SD 3.24 and 1.41, SD 3.49, respectively). Compared with the MT group, the SHS significantly decreased over time in the ITT group (P=.004; Figure 3A). Regarding QHI, the mean scores decreased from baseline at the 1-month recall in all 3 groups (ORT group: 2.2, SD 0.72 to 1.39, SD 0.53; ITT group: 1.79, SD 0.72 to 1.19, SD 0.69; MT group: 1.99, SD 0.84 to 1.74, SD 0.79). However, at the 6-month recall, the scores in the ORT and MT groups increased (ORT group: 1.68, SD 1.11; MT group: 1.86, SD 1.25), while that in the ITT group decreased (0.85, SD 0.63; P<.001; Figure 3B). However, there were no significant differences in H₂S and CH₃SH levels among the 3 groups during the entire study period (Figures 3C and 3D).

Regarding the microbiota, there were no significant differences in the high-risk periodontal microbiota over time among the 3 groups (Figures 4A-4C). Likewise, there was no significant difference in the ratio of caries-risk microbiota to anticaries microbiota between the ORT and ITT groups (Figures 4D and 4E). However, in the MT group, the ratio of caries-risk microbiota significantly increased at the 3-month (P<.001) and 6-month (P=.005) recalls compared with baseline and at the 3-month (P=.048) and 6-month (P=.03) recalls compared with the 1-month recall. Conversely, the ratio of anticaries microbiota significantly decreased at the 3-month and 6-month recalls (Figure 4F).

The groups completed a self-reported questionnaire on current oral care habits and awareness of telemonitoring toothbrushes after finishing the study. On the questionnaire, the most common answers to the question regarding the most effective function of a telemonitoring toothbrush were the brushing guide function by the ORT and MT groups and the standard brushing training by the ITT group (P<.001; Table 2). The most inconvenient feature of the telemonitoring toothbrush was inaccurate toothbrush position recognition, according to participants in the ORT and ITT groups (P<.001). In the ORT and ITT groups, 88% (44/50) and 82% (41/50) of the participants, respectively, indicated that the smart toothbrush was helpful for oral health, and 76% (38/50) and 92% (46/50) of the participants, respectively, reported that their brushing ability had improved. Mean satisfaction with the smart toothbrush was 7.90 (SD 1.21) and 7.11 (SD 1.67) in the ORT and ITT groups, respectively; these were significantly lower in the ITT group than in the ORT group (P=.008). The need for a smart toothbrush was not significantly different between the ORT (mean 7.44, SD 1.64) and ITT (mean 7.71, SD 1.67) groups.

When comparing the average number of toothbrushing events and minutes per toothbrushing event by group, at baseline and after study completion, the number of toothbrushing events decreased significantly in the ORT group (P=.02) and slightly in the ITT and MT groups (Table 3). The average number of minutes spent per toothbrushing event increased in all 3 groups, especially in the MT group (P=.01).

This study demonstrated that ITTs could improve oral hygiene management. The SHS and QHI, indicators of oral hygiene, improved significantly more for the ITT group than the ORT and MT groups when the values at baseline and the 6-month recall were compared between the groups. Along with these results, changes in the oral microbiota were also confirmed. We classified Streptococcus sanguinis as anticaries microbiota and compared its quantitative ratio against caries-risk microbiota, such as Streptococcus mutans, Streptococcus sobrinus, Actinomyces gerencseriae, Scardovia wiggsiae, Veillonella parvula, and Candida albicans. In the ITT group, the proportion of anticaries microbiota increased over time. In the ORT group, the proportion of anticaries microbiota increased until the 3-month recall; however, it decreased at the 6-month recall. In the MT group, the proportion of anticaries microbiota continued to decrease at all time points. Although reducing caries-risk microbiota is important, increasing anticaries microbiota is also an important part of oral hygiene [17,18]. These findings highlight the importance of compliance and sustained engagement in oral hygiene maintenance, which was facilitated by continuous feedback in the ITT group.

The importance of compliance effects for smartphone-based digital health care devices has been reported in previous studies. For example, a telemonitoring application for blood glucose management by individuals with diabetes was effective at the beginning of use, but as satisfaction with the application decreased, the effectiveness also decreased [19]. Using telemonitoring to control asthma has also been reported to be effective. However, a higher level of outpatient care was received compared with national averages [20]; therefore, we cannot rule out the possibility that this may have had an impact on compliance with continued application use.

Based on the questionnaire administered before and after the study, 83% of the participants in the ORT and ITT groups who used smart toothbrushes responded that their brushing abilities improved. Among the 2 groups using smart toothbrushes, the SHS and QHI improved more in the ITT group, whereas satisfaction with the smart toothbrush was higher in the ORT group. This might be due to Oral-B’s fancy hardware and application appearance and easy-to-use charging method compared with the ITT.

In the 2000s, an interactive toothbrush equipped with a monitoring function using toothbrushing and grip axis recognition was introduced [21]. With the advancement in modern technology, it has become possible to provide instructional brushing videos on smartphones and app-based brushing monitoring using real-time motion recognition via Bluetooth [22]. In addition, messages and chat apps are known to help improve brushing, and recently released smart toothbrushes are equipped with various functions, such as messages and motion recognition. An interactive toothbrush with a smartphone app has the advantage of recording toothbrushing data, enabling dental specialists to provide personalized feedback and improve habits through toothbrushing notifications [23,24]. In particular, these findings suggest that children and adolescents who use an interactive toothbrush will benefit from plaque removal and improved gingival health [25-27]. We believe that our study is meaningful in that we have suggested an optimal oral hygiene management method for patients, by comparing clinical efficacy not only between interactive and manual toothbrushes but also between 2 different smart toothbrushes.

The medical paradigm has recently changed to include quick information use and interactive communication using smartphones, which are gradually being used for telemedicine, remote monitoring, and health intervention provision [28-30]. In dentistry, apps to improve oral hygiene are used in various ways, and many studies have verified their effectiveness [31,32]. These innovative smartphone-based mobile apps are also being used as digital therapeutics. Digital therapeutics and software medical devices that provide evidence-based therapeutic interventions to prevent, manage, and treat medical disorders or diseases have been launched in various countries [33]. Moreover, the results of this study showed that smart toothbrushing is not limited to hardware only. An interactive app that encourages the correction of toothbrushing habits has the potential to be used as a digital treatment. In addition, although the duration of and scores for toothbrushing temporarily improved immediately after recall in this study, it was confirmed that interest in brushing had decreased at the 3-month and 6-month recalls, which was probably a long recall period. This suggests that, when using a smart toothbrush, the recall interval with a dental professional should not be too long to promote effective teledentistry treatments, such as a digital therapeutic, and that patient compliance with the smart toothbrush is important.

The ITT group had significant improvements on the SHS and QHI, demonstrating that telemonitoring toothbrushes enable proper oral hygiene management compared with manual and oscillating-rotating toothbrushes. This highlights the importance of expert feedback through the transmission of users’ toothbrushing data. However, it was confirmed that interest in toothbrushing declined at the 3-month and 6-month recalls, which were long recall periods. In the future, additional research will be needed on the appropriate feedback cycle and compliance with the app by participants.