The Effect of Multimedia Message Reminders on Oral Hygiene Promotion during Removable Orthodontic Treatment: A randomized controlled trial

Background: Orthodontic appliances complicate daily oral hygiene maintenance and enhance the formation of microbial biolm on tooth surfaces and orthodontic appliances. Any tool that enhances the oral hygiene of patients during orthodontic treatment would be of imperative benecial. This trial was conducted to assess the effect of message reminders on oral hygiene of patients during removable orthodontic treatment. Methods: In this 2-arm parallel randomized controlled trial, participants were randomly allocated to two groups; one receiving messages reminder and one as the control group. The patients in the messaging group received one or two message reminders and educational videos weekly during the course of treatment. The patients with removable maxillary appliance who were in the age range of 8 to 12 years old and had daily access to Internet to receive message reminders were recruited in this study. A single blinded examiner measured the plaque index (PI), gingival index (GI) and dental caries index of patients in both groups at baseline (T0) and one (T1), three (T2) and six (T3) months after the rst day of treatment to assess their oral hygiene status during the course of treatment in both groups. Results: A total of 50 patients were enrolled and randomized to two even groups (n=25) but only 46 patients completed the study; 22 in control group, and 24 in message reminder group. The PI and GI scores were increased neither in control group nor in message reminder group during T0 and T1, signicantly. The PI and GI scores in message reminder group were signicantly lower than those in the control group at T2 (PI: P=0.003, GI: P=0.001) and T3 (PI: P=0.044, GI: P=0.012). However, slight signicant increasing in the PI and GI score were found during T2 and T3 during in message reminder group. Caries index showed no signicant difference between two group during study. Conclusion: It seems that message reminders can eciently promote oral hygiene of patients undergoing removable orthodontic treatment. Although, this promotion wasn’t progressive. for

This study was a single-center; prospective 2-arm parallel randomized controlled trial with 1:1 allocation ratio. Ethical approval was granted from Ethics Committee of Islamic Azad University, Kazerun branch (IR.IAU.KAU.REC.1399.008) registered in the Iranian Registry of Clinical Trials (IRCT20180923041092N2). There were no changes to the trial after its commencement.
Participants, eligibility criteria, and settings 50 children with age range of 8 to 12 years referred to Department of Orthodontic, School of Dentistry, Shiraz Branch, Azad University (2018-2019) for removable orthodontic treatment were requested to participate in this study if they were willing to do so and did have access to WhatsApp application by smartphone. For the purpose of standardization, children whose treatment plan included the use of a removable orthodontic appliance made of autopolymerizing acrylic resin with a midline screw and had a minimum treatment time of six months, and treated by the same orthodontist (N.N) were enrolled. The time of sending message reminder for each patients was determined with accordance to the time that parents were present at home. The patients who did not have daily access to Internet by their own smartphone or their parents, and patients who suffered from speci c nutritional regimens, systemic diseases, syndromic anomalies such as cleft lip or palate and physical or mental disability were excluded from the study.

Intervention
The participants were divided randomly into two groups of message reminder and control. Both groups received adequate oral hygiene instructions at the beginning of the study. The patients in message reminder group received message reminders in Persian and videos as oral hygiene reminder while the control group did not receive any of these. Participants were not aware of the reason behind sending message reminders or the parameters evaluated in this study.

Experimental group
In the rst phase (T1), the message reminders group received video and text messages containing information about the signi cance of oral hygiene twice a week for 4 weeks (table 1). The message reminders were sent when both parents and patients were at home. The time interval between lunch and dinner was often chosen for most patients. For the rest of the patients, a convenient time was arranged following discussion with the parents. In the second phase (T2), patients received text message and educational videos for oral hygiene once a week for 2 months. In the third phase (T3), message reminders were sent to the message reminder group once a week for 3 months. Thereafter , PI, GI, and dental caries index were recorded at baseline (T0) and one (T1), three (T2) and six (T3) months after the rst day of treatment by the same blinded examiner who did not have any information about participant's division in the two groups. This text message is from the orthodontic clinic. We have to brush our teeth for a minimum of 3 minutes after each meal. Tooth brushing helps maintain sound beautiful teeth.
Hygienic alert! How long does your tooth brush take? 1-2 minutes? Each toothbrush has around 2500 bristles. Allow all of them to do their job and clean your teeth. Your next appointment is soon. If you have forgotten to regularly brush your teeth, start now! Did you know that after eyes, teeth have the greatest impact on facial beauty? Pay more attention to the health and appearance of your teeth! Just wanted to remind tooth brushing after each meal! Do it and see the extraordinary result. See you soon! You are approaching your next appointment fast! Keep up the good work! See you soon! Please make time for tooth brushing. It significantly affects the outcome of orthodontic treatment.
A friendly reminder! Please do not forget to brush your teeth and clean the orthodontic appliance after each meal.
Your smile is the first thing noticed by others. It is your responsibility to keep your teeth clean and it is our responsibility to level and align them by orthodontic treatment.

Control group
The control group did not receive any text message or video during this period. The indices were measured at T0 (onset of study) and at the end of each phase (T1, T2 and T3) similar to message reminder group by the same blinded examiner .
Outcomes (primary and secondary) and any changes after trial commencement The PI was measured using the Silness-Loe PI. 25 For this purpose, presence of dental plaque was evaluated at four areas namely mesiobuccal, buccal, distobuccal and lingual of teeth #44, 24, 32, 12, 36 and 16, and each surface was given a score of 0 to 3 ( Table 2). The GI was determined by assessing the degree of gingival in ammation around teeth #44, 24, 32, 12, 36 and 16. As shown in Table 3 each surface was allocated a score of 0 to 3. This index is used for assessment of the severity of gingival in ammation and its quanti cation. Bleeding on probing is an important criterion in this index. 26 All teeth were examined for caries as shown in Table 4 and were allocated a score of 0 to 6. Presence of caries was determined by clinical examination. 27 Table 2. Plaque Index (PI) ore Presentation

No plaque
A film of plaque adhering to the free gingival margin and adjacent area of the tooth. The plaque may be seen in situ only after application of disclosing solution or by using the probe on the tooth surface.
Moderate accumulation of soft deposit s within the gingival pocket, or the tooth and gingival margin which can be seen with the naked eye.
Abundance of soft matter within the gingival pocket and/or on the tooth and gingival margin.  On the day of delivery of removable orthodontic appliance (T0), patients received a hygienic package including an Oral-B uoridated toothpaste (with 1100 ppm uoride) and a soft Trisa toothbrush (6+ years). Both groups received instructions on tooth brushing during the course of orthodontic treatment and recommendations regarding maintenance of orthodontic appliance. The modi ed Bass tooth brushing technique was taught to all patients. They were requested to brush each of the upper and lower dental arches for 2-3 minutes, three times a day. Also, patients received comprehensive information regarding dental plaque, dental calculus, and their effects on oral health.
No changes to the study design were made after commencement.

Interim analyses and stopping guidelines
Not applicable.

Sample size selection
Randomization Participants were randomized according to the minimization method proposed by Pandis. 28 Randomization ensured patients' allocation to both groups with 1:1 ratio. The rst participant was allocated to one of group at random. For each subsequent participant, we determined that allocation to which group would lead to better balance between the groups in the variables of interest. Allocation concealment, and implementation were performed before randomization process by a researcher who was not involved in the study.

Sample size calculation:
A total of 40 participants were required to achieve 85% power (instituted by G power, version 3.0.1; Franz Faul universitat, Kiel, Germany) and detect signi cant differences considering the effect size of 0.47 (P < 0.05). Considering the possible dropouts, the sample size was increased to 50.
Examiner clinician, the person performing the data entry and the statistician were blinded to the intervention. It was not possible to blind the participants because the patients knew whether they had received the message reminder.

Statistical analysis
Data were analyzed using SPSS version 24. After descriptive analysis of the data, their normal distribution was evaluated using the Shapiro-Wilk test and Levene's test. The effects of sociodemographic such as gender, father's education level (primary school graduate or below, secondary school, post-secondary or above), mother's education level (same grades as father's), father's job (self-employed, employee, unemployed), and mother's job (same levels as father's ) on the patients behavior modi cation in plaque controls were analyzed using Bivariate analysis. For comparison between two groups employed the Mann-Whitney U test, and for others we used the Kruskal-Wallis H test.
Friedman test was used for intra-group comparisons of the mean PI and GI in each group of the message reminder g and control groups among T0, T1, T2, and T3. The Wilcoxon Mann Whitney test was used to compare the mean PI and GI between the message reminder and control groups at each phase (T0, T1, T2 and T3).
The McNemar and Cochrane's tests were used for intra-group comparison of dental caries. The Pearson chi square test was applied to compare the two groups in terms of dental caries at each time point. Level of signi cance was set at 0.05. The intraclass correlation coe cient (ICC) for measurement of PI, GI and caries index was determined by assessing 10

Baseline data
The baseline characteristics for sex, age, and recruitment site in both groups were similar and are illustrated in Table 5. The results of Bivariate analysis between sociodemographic and patient's behavior modi cation in plaque controls are presented in Table 6.     Comparison of message reminder and control groups revealed a signi cant difference in the mean PI at T2 (P=0.003) and T3 (P=0.044). The control group did not show signi cant increasing in PI score during study period. However, PI score in the message reminder group signi cantly decreased over the time from T0 to T2 (P=0.003) and T0 to T3 (P=0.042); and signi cantly increased from T2 to T3 (P=0.014) ( Table 7) (Figure 2). Signi cant differences in GI score between message reminder and control groups was found at T2 (P=0.001) and T3 (P=0.012). GI score in the message reminder group signi cantly decreased from T0 to T2 (P=0.002), T0 to T3 (P=0.043), T1 to T2 (P=0.046) ); however signi cant increase in gingival index was observed during T2 to T3 (P=0.031). In the control group, no signi cant change in PI was noted during the study period; except signi cant increase from T0 to T2 (P=0.043) (Tables 8) (Figure 3).  Dental caries index Table 9 shows no signi cant change in caries index during the study period in the message reminder and control groups (P>0.05). The ICC was found to be 0.81-0.86, which indicated complete agreement in measurements. T 0 to indicate baseline; T 1 , after 1 month; T 2 , after 3 months; T 3, after 6 months * P=.05; ** P=.01; *** P=.001; ****P=.0001

Harms
No harm was observed or reported from the participants in the study.

Discussion
To the best of authors' knowledge, this study is the rst randomized controlled trial to assess the effect of message reminders on oral hygiene status of children and adolescents between 8-12 years using removable orthodontic appliances. In the present study, minimization method was used for participant randomixation; minimization is a method of randomization used to ensure the balance of important prognostic factors among the groups and does not have the disadvantages of other randomization methods. List of randomization is not prepared in this method before the onset of study; instead, it is prepared in the process of selection of participants. It is a dynamic method of randomization. 28 The gender of participants presented no effect on the behavior modi cation in plaque controls in this study; similarly, it has been reported that oral hygiene of patients in xed orthodontic appliances was not different regarding sex differences. [20][21] Mother's and father's job status and their educational level had no sigini cant impact on behavior modi cation. Sun et al, reported that among some family factors such father's and mother's education level and household income, only household income presented the most in uence on subjects' OHRQo. 29 Concerning some cultural impacts, the exact report of household income may not be possible in some population and it may hold some errors and under-report results. Therefore, we ignored this part to be studied.
The effect of message reminders on oral hygiene was evaluated by measuring the PI, GI and caries index. The results showed that the message reminder group had signi cantly lower PI and GI at T2 (3 months after the onset of treatment) and T3 (6 months after the onset of treatment). However, no signi cant difference was found between the message reminder and control groups in PI or GI at T1 (one month after the onset of treatment). According to psychosocial studies, the mean time required for change of behavior to a habit is approximately 66 days. 30 Thus, absence of a signi cant difference between the two groups at T1 may be due to inadequate time for formation of a new habit. 30 Moreover, it has been shown that at the beginning of treatment, the conditions are very challenging for patients since they ought to get used to the new appliance and learn how to practice oral hygiene and clean the appliance. This explains the reason why at T1, challenges encountered by patients to get used to the appliance can result in insigni cant effect of message reminders on PI and GI compared to T2 in the two groups.
Previous studies revealed that orthodontic appliances complicate daily oral hygiene practice in patients ,which may lead to accumulation of dental plaque and microbial bio lm on tooth surfaces and orthodontic appliances. [2][3][4][5] Nonetheless, the current results showed signi cant increase in GI in the control group between T0-T3 and no signi cant increase in PI during the course of study. This trend of change can be due to the fact that patients knew that they were participating in a study and this positively affected the behavior of patients in the control group with regard to oral hygiene. Oral hygiene instructions provided for both groups at the beginning of the study may have in uenced the results accordingly.
Thus, signi cantly lower PI and GI in the message reminder group at T2 and T3 is strong evidence supporting the positive effect of message reminder on oral hygiene status. The current results were in agreement with those of studies that reported the positive e cacy of message reminders for oral hygiene promotion of patients during xed orthodontic treatment. [20][21][22][23] Evidence shows that dental caries following orthodontic treatment can negatively affect the patients' perception of orthodontic treatment, which would negatively impact the future attendance of patients. 20 Although initial enamel lesions may develop within 2-3 weeks following microbial plaque accumulation on tooth surfaces, 31 the current study did not show any signi cant change in caries index in the two groups during the 6-month course of treatment and the two groups were the same in this respect. Eppright et al. 20 suggested that studies on initial enamel lesions should follow-up patients for more than 6 months.
Several studies have evaluated the positive e cacy of SMS and email reminders for acceptance of orthodontic treatment by patients. [20][21][22][23] In our study, the message reminder group showed a signi cant reduction in oral hygiene indices over time compared to the control group; although the trend of this reduction was not the same throughout the study. During T2-T3, a signi cant increase in PI and GI was noted in the message reminder group. Signi cant increase in PI and GI in T3 can be due to the decreased impact of the "novelty effect"; the novelty effect is de ned as initial improvement in performance in response to increased interest in new technology. 18 Thus, after a while, the new technology, i.e. the SMS or email reminders would no longer have its initial novelty and attractiveness and gradually loses its e cacy. Although the current study was performed over a longer period of time (6 months) compared to previous studies, [20][21][22][23] it appears that assessment of the long-term effects of reminders requires further studies.
Sending weekly text or multimedia messages to parents to remind their children to adhere to their oral hygiene protocol does not seem to a di cult task for a private o ce. At present, several communication companies provide services with regard to automatic sending of message reminders and many of such services are available free of charge in the Web. Moreover, particular applications in smartphones can be used as reminders. Providing such services would strengthen the communication between orthodontists and patients and indicate that the orthodontists are concerned about each and every one of their patients. Such behaviors can positively affect the patient satisfaction as well.

Generalizability
The generalizability of these results might be limited to 8 to12 years old children with removable orthodontic appliance.

Limitation
This study was a single-center study; a multi-centric study would increase the sample in a shorter period and would increase validation of results. In this study, we used just clinical indices to determine oral hygiene status, further studies with microbial evaluation of acrylic base plate can be useful.

Conclusion
Sending message reminders and educational videos to parents emphasizing the signi cance of oral hygiene maintenance is an e cient method to promote oral hygiene status of orthodontic patients. Moreover, orthodontists can use an active reminder system to increase patient cooperation during orthodontic treatment.  PI score trend during T0 to T3