About this trial

This study is part of a doctoral research project in Oral Health Sciences and Technologies, with a specialization in Dental Hygiene, at the Faculty of Dental Medicine, University of Lisbon.

With the advancement of technology, smartphones and mobile applications (apps) have become an integral part of daily life, especially among adolescents and young adults, who are the main users of these devices. In 2023, global app downloads reached an estimated 257 billion, including a growing number of health-related apps, known as Mobile Health or mHealth, and, more specifically, apps targeting oral health.

Oral diseases, such as dental caries and periodontal disease, remain a major public health issue due to their high prevalence and impact on quality of life. Although these conditions are preventable, the adoption and maintenance of healthy behaviors continues to be challenging. Mobile apps may serve as an effective complement to oral health consultations, promoting motivation, adherence to recommendations, and communication with healthcare professionals.

Despite the increasing availability of oral health apps, evidence regarding their effectiveness is still limited. Many of these tools lack scientific rigor and fail to adequately meet users' needs.

In this context, an original Portuguese-language mobile application for promoting oral health was developed, based on current scientific evidence and preliminary exploratory studies involving adolescents and oral health professionals. These studies aimed to identify the most relevant features for this type of tool. The app was designed using the Behaviour Change Wheel (BCW) model, widely recognized for structuring effective behavior change interventions in health.

This mobile app was developed by a multidisciplinary team from the University of Lisbon, involving experts from various faculties, including Psychology, Sciences, Dental Medicine, and Fine Arts. As an original tool, it is not yet available on app stores.

The main aim of this study is to test the effectiveness of this app as a complement to oral health consultations in a population of adolescents living in Portugal, contributing to the advancement of knowledge in this field and to the promotion of more innovative and user-centered clinical practices.

These are the specific objectives of the study:

1. To assess the effectiveness of the app when used as a complement to dental hygiene consultations in relation to several oral health indicators, namely risk of dental caries, gingival inflammation, dental plaque presence, and oral self-care behaviors. 2. To analyze the level of satisfaction and usability of the app's features.

The main hypotheses are:

1. The app will significantly improve oral health indicators, including plaque levels, gingival inflammation, and caries risk, compared to a control group. 2. The app will increase adherence to recommended oral hygiene behaviors (e.g., brushing frequency, interdental cleaning). 3. Adolescents using the app will report higher motivation and self-efficacy for oral self-care. 4. The app will demonstrate high usability and user satisfaction, supporting its potential for broader implementation.

Eligibility criteria

This trial accepts healthy volunteers

Qualifiers

Be aged between 15 and 18 years at baseline.

Be fluent in Portuguese.

Have access to a mobile phone or computer/tablet with internet.

Be willing to participate in the study by providing signed assent/consent. For participants under 18 years old, consent must be signed by a legal guardian.

Disqualifiers

Current or previous use of any oral health-related mobile application.

Not being responsible for their own oral hygiene.

Trial design

Design model

Parallel

Treatments tested in this trial

Oral Health Behavioral change
Behavioral
The app includes goal setting (e.g., brushing twice daily, using floss or interdental brushes), self-monitoring tools (e.g., daily brushing checklists), and individualized feedback provided by oral health professionals through a private section of the app. It also incorporates modeling via instructional videos, direct suggestions for healthy habits, reinforcement through badges and motivational messages upon task completion, and prompts to reinforce key messages and behaviours. These components are based on the Behaviour Change Wheel (BCW) framework and are specifically adapted to adolescent users. Although the control group does not receive a digital behavioural intervention, the oral health education and motivational strategies provided during the hygiene consultation are also informed by the BCW framework, ensuring a consistent theoretical basis across both study arms.
MHealth
Other intervention
Use of a mobile application (UL Smile) to deliver structured oral health content and behavioural strategies directly to adolescents via their smartphones. The app provides personalized and interactive tools, including guided brushing animations, educational videos, and digital reminders. It is designed to be used independently by participants throughout the 3-month study period, integrating oral health promotion into their daily routines in a familiar and accessible format. Participants in the control group do not have access to the mobile application and will receive only the standard oral hygiene consultation.
Oral Health education
Other intervention
Delivery of evidence-based information on oral hygiene practices, prevention of dental caries and gum disease, use of oral hygiene products, and the impact of diet on oral health. The educational content in the experimental group is delivered through short, age-appropriate videos and visual resources developed in collaboration with oral health and communication experts. Messages are designed to promote awareness, self-efficacy, and long-term habit formation. In the control group, oral health education is provided through a standard hygiene consultation using traditional methods, such as verbal explanations and demonstration with oral cavity models, without the use of the mobile application.

Treatment groups

150 Participants

are divided into 2 treatment groups

Group A: ULSMILE groupExperimental treatment 3 interventions

Group B: CONTROL groupActive comparator 2 interventions

Trial outcomes

Primary outcomes

1

Dental caries risk assessed by Cariogram

Evaluation of each participant's individual risk of developing dental caries using the Cariogram tool, a validated computer-based model that considers clinical, behavioural, microbiological, and salivary factors to generate a visual and numerical (percentage) estimation of caries risk. This tool incorporates ten parameters, although it is not mandatory to use all of them, the simplified version can be applied with seven parameters, while still maintaining its clinical usefulness. Each parameter is scored on a scale from 0 to 3, where 0 represents the most favourable condition and 3 the least favourable, contributing differently to the final risk estimation. In the present study, due to resource constraints, Cariogram will be applied without the collection of salivary and microbiological data, acknowledging that this decision may reduce the accuracy of the caries risk assessment.

Time frame

Baseline and 3-month follow-up

2

Gingival inflammation

Measurement of gingival inflammation using the percentage of bleeding sites upon gentle probing, following the Bleeding on Probing Index (BOP), which reflects the presence and severity of gingival inflammation.

Time frame

Baseline, 1-month, and 3-month follow-up

3

Dental Plaque accumulation

The Simplified Oral Hygiene Index (OHI-S) will be used to evaluate soft debris and calculus based on two components: the Debris Index-Simplified (DI-S) and the Calculus Index-Simplified (CI-S). Each component measures the amount of debris or calculus on specific tooth surfaces, allowing the effectiveness of oral hygiene practices to be monitored over time. Teeth will be dried and six specific tooth surfaces examined with a mouth mirror and periodontal probe, each surface scored from 0 to 3 for debris and 0 to 3 for calculus, according to the extent of crown coverage. Component scores will be calculated by averaging the surface scores, and the final OHI-S will be the sum of DI-S and CI-S (range 0-6), categorized as excellent (0), good (0.1-1.2), fair (1.3-3.0), or poor (3.1-6.0) to describe oral hygiene status in the trial.

Time frame

Baseline, 1-month, and 3-month follow-up

4

Oral self-care behaviours

Evaluation of participants' oral hygiene behaviours using a structured self-reported questionnaire administered at two time points (baseline and 3-month follow-up). The questionnaire includes 6 items assessing perceived oral health status, frequency and duration of toothbrushing, use of fluoride toothpaste, use and type of interdental cleaning aids (e.g., dental floss, interdental brushes), and frequency of their use. Questions are closed-ended, using yes/no responses, multiple-choice options, or frequency scales, with a few items allowing open responses for further specification.

Time frame

Baseline and 3-month follow-up

Secondary outcomes

1

Oral health knowledge

Evaluation of participants' knowledge regarding oral health concepts, including causes and prevention of dental caries, correct oral hygiene practices, and the importance of diet and fluoride. Data will by validated self-reported questionnaire administered at two time points. Participants answer to 10 items on a 5-point Likert scale.

Time frame

Baseline and 3-month follow-up

2

App usage frequency (UL Smile)

Frequency of use of the UL Smile mobile application, as self-reported by participants during the final questionnaire and based on in-app records, including how often brushing animations, videos, or reminders were accessed. Questions are closed-ended, using yes/no responses, multiple-choice options, or frequency scales, with a few items allowing open responses for further specification.

Time frame

3-month follow-up

3

Perceived usefulness of the app

Participants' perception of the usefulness and impact of the UL Smile app on their oral hygiene behaviours and knowledge is assessed through closed-ended questions, using yes/no responses. Participants are asked whether they found the UL Smile app useful (yes/no). Those who respond affirmatively indicate, via multiple-choice options, which aspects they found beneficial. Options include: motivation to brush teeth at least twice daily, learning correct brushing technique, assistance in maintaining adequate brushing duration, or other specified benefits.

Time frame

3-month follow-up

4

Satisfaction with the mobile application UL Smile

Overall satisfaction with the UL Smile app, including design, clarity of content, ease of use, and relevance to users' needs, assessed through a satisfaction Likert scale in the final questionnaire, ranging from 0 ("not satisfied at all") to 5 ("very satisfied").

Time frame

3-month follow-up

Other outcomes

1

Suggestions for app improvement

Open-ended responses collected in the final questionnaire, where participants are invited to provide suggestions to improve the app's content, design, and functionalities, based on their experience during the study. Responses will be thematically analyzed to guide future development.

Time frame

3-month follow-up

2

Qualitative feedback on app usability

Participants will respond to open-ended questions in the final questionnaire, providing written feedback on their experience using the UL Smile app. They will be asked to identify the feature they liked the most and the one they liked the least, as well as to share any additional comments about what they found helpful or unhelpful. Responses will be thematically analyzed to inform future improvements to the app's content and design.

Time frame

3-month follow-up

UL Smile: A Mobile Health Application to Promote Oral Health in Portuguese Adolescents

About this trial

Eligibility criteria

Qualifiers

Disqualifiers

Trial design

Treatments tested in this trial

Treatment groups

Trial outcomes

Primary outcomes

Secondary outcomes

Other outcomes

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