The concept of “mobile health” (mHealth) refers to the promotion of healthcare through mobile apps and wireless connections [1].

Nowadays, mobile phones are regularly used by people of all ages and may also be useful in medicine to promote prevention and healthy behaviors, allowing everyone to access reliable information anytime and anywhere [2]. These tools aim to monitor significant factors related to diet, exercise, and therapeutic adherence, which play an important role in several diseases ^[3][4][5][3,4,5]. The development of mobile apps was meant to promote prevention, diagnosis, disease management, and therapeutic adherence monitoring [6].

In recent years, dentistry has made steps forward as far as research and technological innovation are concerned, leading to significant progress in all the main dental fields [7].

The invention of 3D printing has revolutionized the production of drill guides and implants in oral surgery and of physical models in orthodontics and prosthodontics [8].

Intraoral scanners have become a fundamental part of the digital workflow; digital impressions allow a more precise bite registration, avoiding distortions related to analogue procedures [9].

Nowadays, it is possible to combine 3D printing and intraoral and extraoral scans to design and manufacture customized appliances for patients affected by craniofacial disorders [10].

Some authors have experimented with the ability of AI (artificial intelligence) to diagnose oral diseases, such as head and neck cancer lesions and periodontitis, but also to make therapeutic decisions, for example, to choose between an extractive and a non-extractive treatment for an orthodontic patient [11]. Research about the use of AI in dentistry is currently growing, involving mainly radiological diagnostic imaging [12]. AI can also play a significant role in orthodontics, helping clinicians to make diagnoses, manage orthodontic treatments, assess patients’ compliance, and make patients feel more involved and cared for [13]. The introduction of teledentistry, a combination of telecommunications and dentistry, has represented an interesting innovation to improve oral healthcare [14]. MHAs represent one of the latest trends arousing interest in the literature [7]. MHAs also represent an important means of spreading oral health care information [15]. In the last few years, an increasingly high number of available health-related apps has been evident, reaching 325,000 apps in 2017 [16], with 612 oral health-related apps that could be downloaded from the App Store in 2019 [17]. MHAs provide meaningful information as far as different fields of dentistry are concerned. They motivate patients to maintain good oral hygiene using positive reinforcement to prevent dental caries [18]. These tools could be particularly helpful for orthodontic patients to avoid plaque accumulation, gingival inflammation, and dental caries, which can lengthen treatment times and result in periodontal health worsening [19].

2. Oral Hygiene

The role of microbial plaque in the etiology of dental caries and periodontal disease is well-known and documented ^[20][63]. Although most of the population performs daily oral hygiene, several studies have reported that most individuals fail to reduce their mouth plaque scores ^[21][64]. According to Toniazzo et al., MHAs can represent an effective tool to improve patients’ oral hygiene ^[22][65]. Some studies showed that MHAs providing patients with brushing instructions resulted in raising awareness of the importance of proper brushing and improving patients’ brushing techniques ^[23][24][42,44]. MHAs have proved to be effective in reducing mouth plaque scores and, consequently, periodontal inflammation and gingival bleeding ^[23][24][25][42,44,47]. Alkadhi et al. observed that MHAs providing oral hygiene instructions can the decrease dental plaque index compared to verbal oral hygiene instructions, although further studies with longer follow-up periods are recommended. A short-term follow-up is mentioned as the limitation of the study. ^[26][41] Similarly, Alkilzy et al. found out that MHAs are useful to reduce plaque accumulation; the results might have been influenced by Hawthorne effects, according to whom subjects involved in a study may tend to modify their behaviors. Furthermore, a longer follow-up period should be considered ^[23][42]. Kay et al. showed that MHAs are successful in improving brushing outcomes, at least in the short term ^[24][44]. It has been observed that adolescents prefer receiving oral health information through smartphone applications and social media ^[27][66]. In fact, Marchetti et al. showed that the use of a mobile oral health app leads to an improvement in adolescents’ periodontal health over a long period of time. The study was conducted in a single school, and this could be a limitation, even if subjects were selected to be representative of the study population. Another limitation is the absence of validation of the questionnaire used ^[25][47].

3. Children’s Oral Health

Early childhood caries (ECC) is known to be the most common chronic disease in early childhood ^[28][67]. Young children are not typically able to perform proper brushing autonomously, so the supervision of parents plays a fundamental role in their oral hygiene ^[29][68]. Parents must teach little children health skills and good eating habits ^[30][23]. Morais et al. described MHAs in their integrative review as effective tools for children, combining educational and interactive approaches ^[31][69]. It has been shown that the use of MHAs improves mothers’ knowledge and practice about children’s oral health. In particular, MHAs were successful in improving children’s gingival status over a long period of time. The study faced some limitations: some smartphones blocked notifications because of security systems, and subjects without smartphones and preschoolers could not take part in it ^[32][50]. Moreover, MHAs represent a modern and particularly successful tool to teach children the correct brushing technique, as reported by the work of Desai et al., in which a significant positive impact on children’s brushing skills was noticed compared to traditional oral hygiene instructions. The limitations of the study are that the sample may not be representative of the study population, a longer follow-up should be taken into consideration, subjects not using a smartphone cannot be involved in the study, and tongue cleaning was not contemplated. Furthermore, the study promoted the modified bass technique, which is difficult to learn for children ^[33][43]. A reduced dental plaque index and better hygienic control were observed in children whose mothers used oral health mobile applications. Nevertheless, it would be necessary to analyze MHAs’ outcomes on dental caries over time and to investigate mothers’ oral hygiene to seek a correlation between mothers’ and children’s oral healthcare ^[34][51]. Oral health practitioners have shown to be favorable to advising MHAs to little children’s parents. Further studies are recommended, extending the research to all the existing app stores and adopting different scales to evaluate clinical outcomes in children’s oral hygiene ^[35][52].

4. Severe Apnea–Hypopnea Sleep Obstructive Syndrome

Obstructive sleep apnea–hypopnea syndrome (OSAHS) causes impaired sensorimotor deficits in the upper airway muscles ^[36][70]. Myofunctional therapy with daily exercises is one of the most novel treatments designed to reinforce the oropharyngeal muscles to avoid the collapse of the upper airways ^[37][71]. According to the recent literature, MHAs provide healthy sleep habits and raise enthusiasm among patients with OSAHS, although further studies are needed to achieve major accuracy and reliability in these apps ^[38][72]. Patients can learn oropharyngeal exercises using MHAs. It has been shown that oropharyngeal exercises performed with the support of mobile applications reduce OSAHS gravity and symptoms. Future studies involving a large number of participants are encouraged to support this evidence. ^[39][48].

5. Compliance and Duration of Treatment of Orthodontic Patients

In recent years, research has led to significant advances in fixed orthodontics, improving bonding techniques with high-performance and innovative materials ^[40][73]. It is well documented that fixed orthodontic appliances make it more difficult to maintain good oral hygiene ^[41][74]. As a result, patients with fixed orthodontic appliances might undergo plaque accumulation, which can lead to the development of white spot lesions or even dental caries ^[42][75]. The duration of orthodontic treatment might be influenced by behavioral factors such as missed appointments, an unplanned debonding of brackets, and bad oral hygiene, which are signs of poor patient compliance ^[43][76]. According to a systematic review, professionals should recommend MHAs since they can be effective in reducing the duration of orthodontic treatment and the intensity of self-reported pain among orthodontic patients ^[44][77]. Furthermore, MHAs can also remind patients about elastic and mobile device wear, promote better oral hygiene, and result in earlier treatment outcomes ^[45][78]. However, it has been observed that a very low to moderate level of evidence supports the effects of MHAs in improving orthodontic patients’ behaviors ^[46][79]. It has been shown that MHAs providing oral hygiene instructions and timely reminders through push notifications improve the oral hygiene of patients with fixed orthodontic appliances, leading to reduced plaque indices and gingival inflammation levels ^[26][47][41,49]. According to Li et al., MHAs are effective in reducing orthodontic treatment duration by improving patients’ compliance and decreasing bracket bond failure. It would be necessary to perform the study on larger samples, involving complex orthodontic cases and adopting a longer follow-up period ^[48][46].

6. Oral Care and Swallowing-Related Quality of Living in Elderly Age

Many elderly people experience xerostomia, swallowing alteration, reduced tongue pressure, and functional impairment of the tongue, mouth, and lips ^[49][80], which can interfere with proper food intake and digestion and, consequently, a good quality of life ^[50][81]. Recently, several MHAs addressed to elderly people have been devised to improve their health and related quality of life ^[51][82]. In particular, some MHAs have been designed to teach elderly people to perform oral exercises and intraoral and extraoral massages to improve their oral health. As a result, Ki et al. described positive effects on elderly people’s oral care: tongue pressure increase, oral dryness reduction, basal salivary flow rate increase, and swallowing-related quality of living improvement. Further studies adopting a longer follow-up period and a larger number of participants are required ^[52][45].

7. Dental Anxiety

Despite the impressive technological innovation of modern dentistry in recent years, many people still suffer from dental anxiety ^[53][21]. Due to this condition, anxious patients tend to postpone or even avoid dental treatments, with consequent negative outcomes for their oral health and related quality of life ^[54][83]. It has been proven that mHealth may be useful to overcome this issue; mobile applications can produce large effects in reducing dental anxiety compared to other non-pharmacological methods ^[55][84]. Huang et al. reported that MHAs allow dentists to perform a teleconsultancy assessing both the physical and psychological patient status. Using this effective tool, the oral health practitioner can follow the patient before the dental procedures, helping to manage dental anxiety up to the post-operative period and addressing possible complications. It should be considered that MHAs’ impact on dental anxiety might be influenced by some aspects, such as sex, age, and possible anxiety disorders, which were not homogeneously represented in the study population ^[56][53].

8. Traumatic Dental Injuries

Dental trauma often occurs in children and adolescents; a proper diagnosis and timely treatment are necessary to allow a favorable long-term prognosis ^[57][85]. In their review, van Mechelen et al. included 18 MHAs, among which only 1 app recommended the use of mouth guards to prevent dental injuries, while none of them suggested how to manage them ^[58][86]. Parents have to be able to properly manage dental trauma. Iskander et al. compared the effectiveness of MHAs and posters to deliver dental trauma information to parents and showed that both these tools were effective ^[59][87]. It is also extremely important to spread knowledge about the management of traumatic dental injuries among non-oral health professionals such as teachers, gym instructors, etc., for whom MHAs have been designed. Zaror et al. validated an MHA regarding dental injury identification and related epidemiologic information collection. The next step is to test this MHA in real cases of trauma in different settings (e.g., schools and gyms) to evaluate its usability in stressful conditions ^[60][61].

9. Dental Erosion

The prevalence of dental erosion is increasing, mainly among young people ^[61][88]. This process has a multifactorial etiology and, if not correctly diagnosed and treated, can lead to esthetic and functional problems ^[62][89]. MHAs have been designed to improve the management of dental erosions. These tools are addressed both to oral practitioners and patients, promoting a stronger relationship between professionals and patients. Butera et al. demonstrated that oral practitioners can use this type of app to monitor the status of patients’ dental erosion over time, detecting possible progressions in the erosive process, while patients can receive personalized oral hygiene instructions from oral practitioners to avoid further deterioration. Preliminary clinical results have been encouraging, and important enhancements to these apps are expected in the future ^[63][64][54,90].

10. Awake Bruxism

Bruxism has been described as a jaw-muscle behavior in otherwise healthy individuals ^[65][91]. Several studies recommended the use of ecological momentary assessment (EMA) principles to study awake bruxism ^[66][25]. A smartphone application has been developed for the EMA of awake bruxism. By sending push notifications, it alerts patients and collects data about their jaw-muscle condition in real time. A good compliance rate has been detected, encouraging further adoption of this tool both for clinical management and research ^[67][56]. Câmara-Souza et al. managed to evaluate awake bruxism frequency in college preparatory students in correlation to psychological factors thanks to MHAs. The authors did not find any difference as far as compliance is concerned between workdays and weekends but noticed that some subjects showed a lack of compliance, probably due to the impossibility of using their smartphones during the day and, consequently, of reacting to the alerts. Therefore, it would be necessary to rely on other technological devices, such as smartwatches ^[68][55]. According to the studies included, MHAs are an effective tool to gather data about awake bruxism that can be used both for clinical activity and research. In fact, these data enable patients to become aware of their habits and monitor their changes over time, promoting a deeper knowledge of this condition ^[69][70][39,58]. It is desirable to carry out further studies involving MHAs to detect the frequency of AB in healthy subjects and in subjects with conditions such as orofacial pain, sleep disorders, and psychosocial impairment to better analyze the correlation with this phenomenon ^[71][72][57,59].