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There has been an increase in consumer-facing mobile health (mHealth) apps in recent years. Prior reviews have characterized the availability, usability, or quality of popular mHealth apps targeting a range of health behaviors, but none has examined apps that promote better oral health care. Oral disease affects billions of people worldwide and mobile phone use is on the rise, so the market for well-designed and effective oral health apps is substantial.
We examined the content and usability of popular oral health promotion apps to better understand the current state of these self-help interventions and inform the need and opportunity for future app development.
Between February and March 2018, we identified oral health-focused apps that were designed for Android or iOS, available in English, and targeted adult consumers (as opposed to children or dental health professionals). The sample was limited to the most popular and highly rated apps on each platform. For each app reviewed, we assessed its basic descriptive characteristics (eg, platform, cost), evidence of a theoretical basis or empirical validation, key program functionality, and the extent to which the app addressed diet and tobacco and alcohol use as risk factors for oral disease. We characterized the framing (ie, gain vs loss) of all persuasive messaging and conducted a heuristic analysis to assess each app’s usability as a persuasive health technology.
Thirty-three apps were eligible for review based on the selection criteria. Two-thirds (22/33, 67%) were geared toward the general public as opposed to dental clinic patients, insurance plan members, or owners of specific electric toothbrushes. Most (31/33, 94%) were free to download, and a majority (19/33, 58%) were sponsored by software developers as opposed to oral health experts. None offered any theoretical basis for the content or had been empirically validated. Common program features included tools for tracking or reminding one to brush their teeth and assistance scheduling dental appointments. Nineteen apps (58%) included educational or persuasive content intended to influence oral health behavior. Only 32% (6/19) of these included a larger proportion of gain-framed than loss-framed messaging. Most of the apps did not mention diet, alcohol or tobacco—important risk factors for oral disease. Overall, the apps performed poorly on standard usability heuristics recommended for persuasive health technologies.
The quality of the reviewed apps was generally poor. Important opportunities exist to develop oral health promotion apps that have theoretically grounded content, are empirically validated, and adhere to good design principles for persuasive health technologies.
Untreated oral conditions, including dental caries, severe periodontitis, and edentulism, affect about 3.5 billion people worldwide [
We believe mobile phones offer a promising strategy for reaching the public to deliver low-cost oral health promotion apps. According to a 2018 survey by the Pew Research Center, 77% of US residents now own a mobile phone [
Along with the growth in mobile phone usage, there has been rapid growth in consumer-facing health promotion apps [
Prior reviews have examined the efficacy of mobile health (mHealth) apps for behaviors such as weight loss and physical activity [
To address the gap in the literature and inform future oral health intervention development, we conducted a systematic review of the most popular oral health apps available for Android and iOS phones. To do this, we sought to review the content and assess the usability of each app. Our content review included an examination of the basic features and functionality, inclusion of key oral health discussion topics, analysis of message framing, and assessment of whether the developers cited a theoretical or empirical basis for the content. The findings from this comprehensive review inform the overall quality of popular oral health promotion apps and speak to both the need and opportunity for additional mHealth intervention development.
We identified oral health-focused apps in the App Store and Google Play between February and March 2018. Apps were identified using the following search phrases:
To limit the search to those most popular, we followed the example of Abroms et al [
For each app we documented the developer/sponsor, platform, cost, number of installations, and user ratings. We summarized the basic functionality and noted whether the app or its descriptive summary at the app store indicated that it had been empirically validated. We also conducted a literature review to identify empirical evaluations that might be included in the list. Next, we documented whether each app or its descriptive summary included any reference to a theoretical or empirical basis for the educational or persuasive content.
In addition, we characterized the framing of all persuasive health messages used. According to prospect theory, potential losses are more motivating than potential gains when risky actions are being considered, but gains are more motivating than losses for low-risk behaviors [
Because diet and tobacco and alcohol use are important risk factors for oral disease [
All content was reviewed and characterized using the methods outlined above by the first author (BT). A second reviewer (JM) reviewed the summarized findings and validated the first author’s characterization of key content elements including message framing, level of discussion focused on key topics such as tobacco and alcohol, and whether the content linked diet, alcohol, or tobacco to oral disease risk.
Each of the apps reviewed is an example of a persuasive health technology [
To further assess the quality of the selected apps, we reviewed and rated each based on 10 heuristics recommended for improving the usability of persuasive health technologies [
Appropriate functionality: technology should meet usability, mobility, visibility, and durability needs according to the settings in which it might be used. The technology should function effectively in the user’s environment by being easy to use and integrate into one’s daily life and routine.
Not irritating or embarrassing: technology should not irritate or embarrass the user, even after using the product repeatedly and regularly over a long period of time. This relates to aspects such as the presence of the product itself in the user’s environment; the degree to which the technology intrudes upon the user’s daily life; the timing, type, accuracy, and amount of feedback given; and the capability for customized settings and privacy controls.
Protects user’s privacy: system allows users to keep personal information private. Users can control what, when, to whom, and how much information is made public. Any public information is kept abstract.
Use of positive motivation strategies: technology recognizes when target behaviors have been performed or goals have been met and uses positive reinforcement strategies to promote continued progress. App avoids use of punishment for failure to perform target behaviors or meet goals.
Usable and aesthetically appealing design: visual design of the technology is attractive and appealing and adheres to basic usability standards. Design captures and sustains the user’s interest, enhances user engagement with the technology, and adds to the credibility and usability of the product.
Accuracy of user information: technology should not inaccurately record or misrepresent the user’s behavior (for instance, due to limitations in automatic sensing capabilities or the inability to use the device in certain environments). If necessary—to obtain an accurate, comprehensive account of behavior—the technology should allow users to edit data records and/or manually input additional data that the device is incapable of detecting automatically.
Appropriate time and place: information, feedback, and assistance are provided at an opportune time and place (ie, when and where it is needed, at the most appropriate time, and in the most effective manner).
Visibility of user’s status: technology should always keep the user informed about progress toward goals through appropriate feedback within a reasonable time frame. Feedback is accurate and easily understood (eg, through use of abstract displays, summary data).
Customizability: users should be able to customize aspects of the technology, for example, creating personalized goals and customizing product settings (public/private data, interface, etc). However, customizability should not interfere with persuasive aspects.
Educate users: users should understand why their actions promote positive behaviors and how their goals are being met. This includes which specific behaviors lead to the accomplishment of a larger goal. The technology should engage users in an active process whereby they learn information and gain skills relevant to their goals, particularly skills that would enable them to continue to progress toward goals even in the absence of the technology.
Best and worst case examples of usability by heuristic domain.
Heuristic | Best case | Worst case |
Appropriate functionality | Has a comprehensive set of persuasive health features such as a toothbrush timer, goal tracking, and reminders that run smoothly Is intuitive and easy to use Free of errors and crashes |
Primary function is a toothbrush timer, which doesn’t work Lacks basic features such as reminders, sound controls, etc. Has frequent errors and crashes repeatedly |
Not irritating or embarrassing | Free of ads and other unnecessary interruptions Functions smoothly, navigation is intuitive, and screens and features load quickly Gives user the ability to customize settings and controls such as sound, timer length, and privacy |
Frequently interrupts user with full-screen ads, flashing banners, and solicitations Slow loading times; disorganized, inconsistent navigational controls No user guides, assistance, or help of any kind provided |
Protects user’s privacy | Log-in/password protected Informs/reassures user about privacy protections and rights Allows user to control their data permissions/usage |
No log-in/password option No mention of privacy policy or what happens to data Shares data publicly or with third parties such as advertisers |
Use of positive motivation strategies | Primarily uses gain-framed messaging and positive imagery throughout Positively reinforces achievement of target behavior: “Great job! Keep it up!” Rewards user with badges, points, or other incentives when achieving target behaviors/goals |
No positive motivation strategies are used at all; says nothing when you complete a tooth brushing session Primarily uses loss-framed messaging and negative imagery (eg, cartoon of person suffering from bad breath) Warns potential mates will run from you if you have bad breath |
Usable and aesthetically appealing design | Interface is well designed and professional looking High-quality, attractive images and graphics are used Navigational elements and controls are intuitive and easy to use, keep the user well oriented |
Unappealing color choices, such as a puke-green background Poor image quality; pixelated, unattractive imagery and graphics; reuses the same image for different sections Disorganized, disorienting, and inconsistent navigation controls |
Accuracy of user information | Option to track multiple aspects of user information and behavior Tracking features are accurate, editable, and function appropriately Allows user to manually input, edit, or delete their information |
Has no ability to track or store user information/behavior Tracking features do not function properly or are highly inaccurate Does not provide a way to input, edit, or delete existing user information |
Appropriate time and place | Information is coherent and well organized for consumption Provides user with mini-tutorials when accessing new features Simply shaking the device allows the user to easily report an issue |
Textual information is plagued by spelling, grammatical, or syntax errors; difficult to consume No guides, assistance, or help of any kind is provided for the user App randomly asks user to solve math problems |
Visibility of user’s status | Provides summary data of user’s stats on home screen Provides more in-depth explanation of user progression data with historical graphs/charts Shows progression bars as user works toward goals |
No user data is tracked, so there is no feedback on status or progress towards goals Does not let the user know which content they’ve reviewed; doesn’t provide option to do so Toothbrush timer is tiny; difficult to see progress |
Customizability | Provides ability to customize colors, sounds, and notifications Provides ability to choose from among several oral hygiene goals Provides ability to create multiple user profiles so a family can share the device, for instance |
No ability to customize colors, sounds, or notifications No ability to set personalized goals or tailor oral hygiene strategies, such as timer length No ability to customize privacy settings or control user data |
Educates users | Provides educational material on the benefits of oral hygiene practices Provides videos that explain how to properly brush, floss, and perform other types of oral care Positively reinforces target behaviors by reminding user of end-goal benefits |
No educational, instructional, or persuasive content whatsoever No clear goals for the user to achieve Does not attempt to engage the user in any process or explain why user should perform certain types of behaviors |
For each of the heuristics above, we applied a standard severity scoring system recommended by Nielsen [
A total of 33 apps met the selection criteria and were reviewed (
Common design features included the ability to provide feedback on the app (12/33, 36%), customize aspects of appearance or sounds (12/33, 36%), set up a log-in account (9/33, 27%), access customer support (9/33, 27%), customize one’s oral health goals (8/33, 24%), and share progress with others (5/33, 15%). Four apps (12%) specifically promoted oral hygiene products for purchase; 6 included gamification features such as awarding badges for behavioral milestones and accomplishments.
Key functions are presented in
None of the apps cited a theoretical foundation for design or content. Only 1 mentioned any evaluation of the app’s impact on changing users’ knowledge, attitudes, or behavior. The cited study, however, was limited to a cross-sectional survey of users’ perceptions and did not assess the actual effectiveness of the intervention in a randomized or longitudinal study [
More than half (19/33, 57%) of the apps included written content intended to influence oral health behavior as opposed to simply providing instructional directions for how to use the features or functionality (eg, toothbrush timer). The majority of these apps (15/19, 79%) included a mix of gain- and loss-framed messages (
Examples of gain-framed messages included:
To keep your teeth and gums healthy you should clean between teeth daily with floss or an interdental cleaner.
Brush your way to a fresh smile.
Examples of loss-framed messages included:
In general, the higher the frequency and quantity of sugary foods and drinks you intake per day, the more at risk you are of developing tooth decay.
If you don’t floss and brush your teeth regularly, any food trapped between your teeth will be broken down by the bacteria and may be responsible for bad breath.
Twelve apps (36%) included some discussion of diet, but the discussion was either brief (5/12, 42%) or partial (5/12, 42%). Only 2 provided more comprehensive dietary information. Most of the apps that mentioned diet (7/12, 58%) recommended limiting or avoiding sugary foods that cause tooth decay or bad breath, and 33% (4/12) mentioned that acidic food or drinks can damage teeth. Several apps (3/12, 25%) endorsed eating a diet rich in fruits and vegetables, but 1 suggested eating fruits and vegetables could stain one’s teeth.
Eleven apps (33%) briefly or partially discussed tobacco use. None included a full discussion of the effects of tobacco on oral health outcomes. Five of the 11 apps that included some tobacco discussion (45%) advised people not to use or to quit tobacco, 36% (4/11) emphasized tobacco’s role in causing bad breath, 36% (4/11) emphasized that tobacco causes tooth stains, and 36% (4/11) linked tobacco use to oral disease. None referred people to stop-smoking treatment services.
Nine apps (27%) briefly addressed alcohol use. Seven of these (7/9, 78%) suggested drinking be limited or avoided to reduce the risk of unwanted oral health issues such as bruxism, bad breath, dry mouth, tooth decay, or stained teeth. Only 1 app noted that alcohol use is a risk factor for oral cancer. None referred people to treatment services to reduce their drinking.
Reviewed apps.
Name | Platform | Sponsor | Cost | Number of installsa | Number of user ratingsa | Average user ratinga |
24/7 Live Dentist Response | iOS | Digital health company | Free | Unknown | Unknown | Unknown |
Bad Breath | Android | App developer | Free | 1000 | 3 | 3.7 |
Bad Breath Guide | iOS | Dental provider | Free | Unknown | Unknown | Unknown |
Brush DJ | Android & iOS | App developer | Free | 100,000 | 1207 | 4.1 |
Brushing and Whitening Teeth | Android | App developer | Free | 5000 | 106 | 4.4 |
Brush'n'Save | Android | Dental provider | Free | 10,000 | 74 | 4 |
Brushy | Android | App developer | Free | 10,000 | 115 | 3.3 |
Colgate Connect | iOS | Oral hygiene product company | Free | Unknown | 81 | 4.3 |
DDS Anywhere | Android & iOS | App developer | Free | 5000 | 23 | 4 |
Delta Dental | Android & iOS | Insurance provider | Free | 100,000 | 793 | 3 |
Dentacare - Health Training | Android | App developer | Free | 10,000 | Unknownb | Unknownb |
DentAdvisor: Oral Care Expert | iOS | App developer | $1.99 | Unknown | Unknown | Unknown |
Dental Care | Android | App developer | Free | 1000 | 9 | 4.6 |
Dental Care—Target Smile | Android | App developer | Free | 1000 | 40 | 4.9 |
Dental Desk | Android | Dental provider | Free | 10,000 | 66 | 4.6 |
Do I Grind | Android & iOS | Digital health company | Free | 1000 | 40 | 4.1 |
FoodForTeethc | iOS | Dental provider | Free | Unknown | Unknown | Unknown |
Healthy Teethd | iOS | App developer | Free | Unknown | Unknown | Unknown |
Kolibree | Android & iOS | Oral hygiene product company | Free | 5000 | 136 | 3.3 |
Let’s Brush Free | iOS | App developer | Free | Unknown | Unknown | Unknown |
Moment of Tooth | iOS | App developer | Free | Unknown | 8 | 4.9 |
My Dental Care | Android & iOS | Dental provider | Free | 500 | 14 | 5 |
MySmile | Android & iOS | App developer | Free | 10,000 | 126 | 4.1 |
Oral-B App | Android & iOS | Oral hygiene product company | Free | 1,000,000 | 12,489 | 3.3 |
Philips Sonicare | Android & iOS | Oral hygiene product company | Free | 50,000 | 564 | 2.7 |
QuickBrush Toothbrush Timer | Android | App developer | Free | 10,000 | 176 | 4.2 |
Smile—Dental Hygiene Analysis | iOS | Dental provider | Free | Unknown | 14 | 3.6 |
Tooth Notes | iOS | App developer | $0.99 | Unknown | Unknown | Unknown |
Toothbrush Pacer | Android | App developer | Free | 10,000 | 98 | 4 |
Toothbrush timer | Android | App developer | Free | 100,000 | 1046 | 3.5 |
Toothbrush Timer | Android | App developer | Free | 50,000 | 776 | 3.8 |
Toothy: Brush Floss Rinse! | iOS | App developer | Free | Unknown | 401 | 4.6 |
United Concordia Dental Mobile | Android & iOS | Insurance provider | Free | 50,000 | 232 | 3.3 |
aDetails on the number of installations, number of user ratings, and average rating are only available in the App Store for some iOS-based apps. Data presented on apps available for both Android and iOS list data from Google Play only. User ratings scored on a 1 (worst) to 5 (best) scale. All data were current as of the time of this review.
bThis app was released as a beta version, so rating information was not yet being tracked.
cFull app name: FoodForTeeth—Food Database and Diet Diary.
dFull app name: Healthy Teeth—Tooth Brushing reminder with timer.
Summary of key app functions.
Key function | Total, n (%) |
Tooth brushing timer | 20 (61) |
Tips for better oral hygiene | 16 (48) |
Oral health educational content | 13 (39) |
Oral hygiene alerts or reminders | 13 (39) |
Tracking of oral health behaviors (eg, brushing) | 9 (27) |
Tracking of dental appointments | 7 (21) |
Ability to communicate with a dental professional | 5 (15) |
Ability to search for dentists | 5 (15) |
Gain and loss framing in apps with persuasive health messages. Table does not include apps that provided instructional content only (n=14).
App name | Total messages, N | Gain framed, n (%) | Loss framed, n (%) | Neutral framed, n (%) |
MySmile | 22 | 0 (0) | 9 (41) | 13 (59) |
Do I Grind | 21 | 3 (14) | 11 (52) | 7 (33) |
Delta Dental | 81 | 8 (10) | 30 (37) | 43 (53) |
Bad Breath | 159 | 31 (20) | 46 (29) | 82 (52) |
United Concordia Dental Mobile | 113 | 7 (6) | 18 (16) | 89 (79) |
Bad Breath Guide | 352 | 48 (14) | 74 (21) | 220 (63) |
Brushing and Whitening Teeth | 424 | 9 (2) | 16 (4) | 98 (23) |
Dental Desk | 172 | 6 (4) | 16 (9) | 154 (90) |
FoodForTeetha | 499 | 50 (10) | 73 (15) | 377 (76) |
My Dental Care | 691 | 45 (7) | 70 (10) | 576 (83) |
DentAdvisor: Oral Care Expert | 909 | 42 (5) | 77 (9) | 777 (86) |
QuickBrush Toothbrush Timer | 13 | 1 (8) | 1 (8) | 11 (85) |
Brush DJ | 19 | 0 (0) | 0 (0) | 19 (100) |
Dental Care | 430 | 69 (16) | 65 (15) | 295 (69) |
Dental Care—Target Smile | 48 | 1 (2) | 0 (0) | 47 (98) |
Moment of Tooth | 21 | 8 (38) | 5 (24) | 8 (38) |
Let’s Brush Free | 21 | 5 (24) | 0 (0) | 16 (76) |
Philips Sonicare | 11 | 8 (73) | 1 (9) | 2 (18) |
Oral-B App | 23 | 18 (78) | 2 (9) | 3 (13) |
aFull app name: FoodForTeeth—Food Database and Diet Diary.
Although not all the reviewed apps included explicit health persuasion messages, all were intended to influence users’ oral health attitudes and behavior. Thus, we reviewed all 33 apps using the heuristics recommended for persuasive health technologies.
Number of apps receiving usability severity scores for each persuasive health technology heuristic.
Heuristic | No issues (score=0) | Cosmetic issues (score=1) | Minor issues (score=2) | Major issues (score=3) | Usability catastrophe (score=4) |
Appropriate functionality | 0 | 0 | 5 | 26 | 2 |
Not irritating or embarrassing | 0 | 1 | 9 | 20 | 3 |
Protects user privacy | 2 | 0 | 4 | 5 | 22 |
Use of positive motivation strategies | 0 | 3 | 1 | 17 | 12 |
Usable and aesthetically appealing design | 0 | 6 | 13 | 12 | 2 |
Accuracy of user information | 0 | 0 | 3 | 14 | 16 |
Appropriate time and place | 0 | 4 | 2 | 25 | 2 |
Visibility of user status | 0 | 4 | 1 | 20 | 8 |
Customizability | 0 | 0 | 5 | 10 | 18 |
Educates users | 0 | 0 | 4 | 20 | 9 |
We selected 33 of the most popular and highly rated oral health apps available for Android and iOS and reviewed the design, content, and usability of each. As a group, apps were of poor quality. All were intended to influence adults’ oral health attitudes and behaviors, but none were empirically validated to demonstrate their effectiveness. None cited any theoretical basis for the content, which is not unusual for mHealth apps, but since the majority were created by developers who did not appear to be affiliated with oral health or behavioral science experts, it is likely that the content and design of most were not driven by sound behavioral theory. As a case in point, prospect theory suggests that gain-framed messages are more effective at promoting preventive health behaviors than loss-framed messages [
The oral health educational content had other issues, as well. For example, diet, tobacco, and alcohol are significant risk factors for oral disease [
It is also notable that of the apps that included any discussion of tobacco and alcohol, very few linked use of these substances to oral cancer risk. Most highlighted the cosmetic (eg, stained teeth) or social implications (eg, bad breath) of their use instead. Given the independent and synergistic effects that these substances have on oral disease [
Finally, the reviewed apps all had significant usability issues based on our heuristic review. Only 2 took measures to protect users’ privacy, and none received a perfect severity score (ie, 0) on the other 9 heuristics. Significant usability issues (severity score of 3 or 4) were noted for most apps across the heuristic domains. Three apps sponsored by companies promoting oral health products (Oral B, Philips Sonicare, and Colgate Connect) were generally well designed and received higher scores but were narrowly intended to promote use of their products, resulting in lower overall scores as persuasive health technologies.
This study has a number of notable strengths, including its novelty. To our knowledge, this is the first review of oral health promotion apps. As such, this paper addresses an important gap in the literature. It also establishes the need and opportunity to create high-quality oral health promotion apps targeting adults. Oral disease affects billions of people worldwide [
Another strength of this review is its comprehensive nature, in which both the quality of persuasive health content and user-centered design of the apps were evaluated. Our application of Kientz’s persuasive health technology heuristics is also novel. Typically, these heuristics are used to identify a range of user issues and each issue is scored based on its severity rather than assigning a score to each heuristic domain or an overall severity score to the entire app. However, our approach was reasonable for the purposes of this review since it allowed us to compare the relative quality of the user design across apps using a common evaluation and scoring scheme.
Study limitations should also be noted. First, it is possible that there are existing oral health apps which are of higher quality than that of the most popular apps we reviewed. Resource restraints prevented us from reviewing all of the available apps (nearly 3000 were identified based on our keywords), but we believe our focus on the most popular apps is reasonable because these are the apps which are most frequently being used by the public. Next, the downside of our comparative heuristic review is that it treated each heuristic as equally important, which may not be the case. For this reason, we presented both overall app severity scores and domain-specific scores so readers can get a better sense of where usability issues were observed. But we acknowledge that depending on the nature of the app, performance in some heuristic categories may be more important than others so in future reviews it might be more appropriate to differentially weight the domains. Another limitation is that our heuristic review was performed by a single coder trained in user-centered design using standardized scoring criteria. More typically, if the goal had been to delineate all of the observed issues, a group of coders might be used. This was prohibited due to limited project resources but is also unlikely to have changed our conclusion about the quality of the design of these apps as a group based on the pervasiveness and severity of issues observed. Finally, we note that our review was limited to content that was available through installation of each app. Additional content only available to certain audiences such as health plan members or owners of purchased electric toothbrushes and protected via account log-in could not be viewed.
Many oral health apps are available to consumers, but based on this review of the most popular and highly rated ones, the quality of these apps is generally poor. Important opportunities exist to develop oral health promotion apps whose content is theoretically grounded and evidence-based and that adhere to good design principles for persuasive health technologies.
This research was supported by the National Institute for Dental and Craniofacial Research (U01DE024462; principal investigator: JBM). We are grateful to Ella Thompson for her management of this project, Tooka Zokaie for her participation in an initial review of available oral health apps, and Annie Shaffer for her assistance with the final manuscript preparation. A portion of the findings in this paper were presented at the 2018 annual meeting of the Society of Behavioral Medicine in New Orleans, Louisiana.
None declared.