This study was conducted strictly on patients who received cobalt–chromium RPD dentures processed at the Faculty of Dentistry, UKM, and delivered by undergraduate students under the supervision of specialists within a 2-year duration. These criteria ensure standardisation in the material and design principles of the RPD, which influences gingival health [27]. A maximum duration of 2 years was selected as older RPDs without adequate postplacement care may have integrity defects [28]. Participants above 75 years were excluded due to possible changes in cognitive function [29] and manual dexterity [30], which may both affect the study outcome.
Most published studies on dental-related mobile applications were native applications. PWA was chosen in the present study because of its multi-platform advantage. Phone operating systems and application stores do not restrict its usage, hence the cost-effective development and distribution [31]. PWA also requires less installation space than native application, thereby addressing user’s memory space concern [32]. Although PWA is inferior to native application in terms of its ability to access user contacts or calendar, this extra feature was not necessary in the ‘Oral and Denture Guide’ PWA.
The scale in the index by Jeganathan et al. is widely used to assess the DP in RPDs [8, 33, 34] and presents high values of agreement with reliability test [25]. Consistently measuring the distribution of plaque on dentures is difficult to perform by visual inspection alone [35]. Thus, in the present study, dentures images were superimposed with gridlines to aid in scoring, as described in the methodology section earlier. Scoring was conducted by a single examiner to reduce measurement error [35].
To the authors’ knowledge, this is the first clinical study to develop and evaluate the efficacy of a mobile application for post-denture delivery education of patients with RPD. The results revealed no significant difference in knowledge gain between the participants in the PWA and control groups. Comparison with previous studies [7, 8] on the influence of the method of education on RPD wearers’ knowledge was not possible because these studies measured oral hygiene instead of knowledge score as an outcome.
Considering the participants who installed the PWA had the advantage of having a take-home reference material, their performance was expected to improve during the follow-up test at T2. However, the results showed a decline in their knowledge scores compared with that at T1, which was a similar trend to that in the control group. This outcome differed from the findings of Marchetti et al., who revealed knowledge gain and retention in participants exposed to mobile application. These positive results were attributed to the periodic reinforcement of oral health education by the mobile application developed in their study [15].
On the contrary, active reminders were not sent to the PWA participants in the current study, because the authors were interested in knowing the actual usage on the basis of the participant’s own initiative. Moreover, the study by Marchetti et al. was conducted on adolescents, whereas half of the participants in the present study were seniors. The storage capacity of working memory differs between older (aged 60–79 years) and younger (aged 18–25 years) individuals [36]. Furthermore, some processing deficits of the working memory possibly exist in older adults [36], thereby reducing their knowledge scores in the questionnaire.
Despite the drop in the knowledge scores during T2, the significant increase in the scores compared with those during T0 showed that the PWA was indeed effective in delivering valuable information to the participants. Comparison of knowledge gain between the participants below 60 years of age and those aged 60 years and above revealed no significant difference, indicating that the elderly benefitted from the PWA as much as the younger age group. This finding is encouraging, because it may address the problem of elderly patients receiving insufficient denture care information [6, 37].
The participants’ oral hygiene was significantly improved by the ‘Oral and Denture Guide’ PWA compared with that of the control group. This finding was in agreement with the findings from the studies on oral-hygiene focused applications [14, 16]. Although no significant difference was found in the PI score between the PWA and control groups, gingival status may be a more reliable measurement of improvement in oral hygiene [38]. The plaque levels assessed may be misleading, because some participants could be more meticulous with their oral hygiene on the day of measurement, resulting in less plaque.
For denture hygiene, no significant difference was found in the DP scores between the PWA group and the control group. This result differed from that of Ribeiro et al., who reported better denture hygiene in the group provided with written illustrated educational material than in the control group [8]. However, this significant difference only started to become evident at the 6-month and 12-month reviews, whereas the participants in the present research were only followed up for 3 months. Moreover, denture hygiene instructions were repeated when necessary during the review sessions. Thus, Ribeiro et al.’s positive results may be attributed to the periodic reinforcement.
Acceptance is an attitude towards a technology that could influence technology adoption. In the present study, the participants’ acceptance of this educational approach was assessed by exploring the actual usage [26] and their response to PWA. The usage frequency (Fig. 4) was lower than that obtained by Underwood et al., who reported that 44.8% of participants used the oral health application of interest two times daily. However, most of them used it for less than a week [10]. Although the reported frequency of use was high, the majority of their participants were aged 7–12 years. Moreover, the data reported were based on self-reported usage, which is a subjective measure, whereas the values reported in the present study includes data from the usage log statistics [26]. Besides, the participants in the present study reported that they mainly used the PWA as a source of reference and found the section on denture care to be most useful, thereby substantiating the role of PWA in conveying post-denture delivery instructions. Considering that elderly people take time to adopt new technologies but do so if they find these technologies beneficial [39], the participants’ overall response towards PWA was reasonably good.
This study had some limitations. Some differences may exist amongst the RPDs that possibly influenced the GI scores between the PWA group and the control group. Given that the participants received their RPDs within a 2-year duration, increased surface roughness in old dentures [40] could affect cleanliness. Denture design factors, such as the lingual plate major connector, may affect not only the quantity but also the quality of plaque intraorally; thus, these factors may have considerable effects on gingival health [33].
Besides, the participants were only followed up for 3 months without periodic reinforcement during reviews. Retention of the knowledge gained and improvement in behavioural habits over an extended period were not certain. Moreover, participants may not change their old practises on denture care despite acquiring new knowledge [7]. Thus, the effect of the knowledge gain on their denture hygiene routine is uncertain. The results obtained could not be extrapolated to the general population because the PWA may only be useful to a specific group in the society due to limitations, such as language, literacy and the need for a mobile device with Internet access.
Future studies may incorporate behaviour modification techniques when developing mobile applications and exploring their effect on denture hygiene utilisation and habits. Mobile applications could also be improvised, such as adding a read-out loud function or using comprehensive videos to overcome issues of language and literacy. Mobile applications are expected to be widely used amongst all ages in the society as smartphones gradually replace conventional mobile phones. The results of this study suggested that the elderly are receptive to this new educational approach; thus, mobile application developers should consider them as target users and incorporate design features that are user-friendly for elderly people.