Effectiveness of “Safeguard Your Smile,” an oral health literacy intervention, on oral hygiene self-care behaviour among Punjabi immigrants:A randomized controlled trial

Abstract

Background

Research shows that immigrants have higher rates of oral diseases, poorer access to dental care services, and lower levels of health literacy than their Canadian-born peers. Oral health literacy has emerged as a potential pathway to reduce oral health disparities. The scarcity of studies on oral health literacy interventions, particularly among immigrants, lent urgency to this study, the purpose of which was to evaluate the effectiveness of an oral health literacy intervention promoting oral hygiene self-care behaviour among Punjabi immigrants.

Methods

The study used a parallel group, non-blinded, randomized controlled trial design. One hundred and forty (140) Punjabi immigrants between 18 and 60 years of age were enrolled. Participants were randomly allocated to receive either the Safeguard Your Smile (SYS) intervention or a conventional pamphlet. The following outcome measures were assessed at baseline and 3 months post-intervention: self-reported oral hygiene self-care behaviour and knowledge, plaque and gingival indices, and oral health literacy. A linear mixed model for repeated measures was used to compare the intervention and control groups (between) at pre- and post-intervention (within).

Results

Participants who received the SYS intervention showed improvements ( p <0.0001) for the following dependent variables: oral hygiene self-care knowledge and behaviour, oral health literacy, and plaque and gingival indices.

Conclusions

SYS intervention enhanced positive oral hygiene self-care behaviour among Punjabi immigrants with low oral health literacy. SYS intervention can be employed among other vulnerable groups with low levels of oral health literacy to improve oral hygiene self-care behaviour.

WHY THIS ARTICLE IS IMPORTANT TO DENTAL HYGIENISTS .

• Oral health literacy is an important determinant of oral health.

• Immigrants have lower oral health literacy levels and higher rates of oral diseases than their Canadian-born peers.

• This study shows that a community-based oral health literacy intervention designed for an immigrant population improved oral hygiene self-care behaviour and clinical outcomes for this group.

INTRODUCTION

G ood oral health is integral to general health and is vital for one’s overall quality of life and well-being.¹ To date, preventable oral diseases such as dental decay and gum diseases remain concentrated among vulnerable Canadian populations such as immigrants, Indigenous peoples, and seniors.² In 2014, Ghiabi et al. reported that 53% of immigrants had untreated dental decay, 89% had gingivitis, and 73% had periodontitis versus 32% of native-born Canadians.³

It has been reported that immigrants experience a gradual deterioration in their general health status^{4, 5} in part due to significant economic, cultural, and linguistic barriers to care, and limited health literacy.⁶ Calvasina et al. reported that Brazilian immigrants face challenges accessing and navigating the Canadian dental care system because of low income, language barriers, and lack of self-efficacy/knowledge about the dental system.⁷ Brodeur et al. conducted a survey of 5,795 immigrant women in Quebec and found that recent immigrant women use fewer preventive dental services as compared to long-term immigrants and non-immigrants.⁸ This reported difference was primarily due to financial and cultural barriers.⁸ MacEntee et al. stated that older Punjabi-speaking immigrants have difficulty accessing a dentist and that they manage their oral diseases with either home remedies, emergency room visits or during return visits to India.⁹ Marshall et al. reported that Punjabi and Chinese populations have unmet general health needs including dental care due to economic reasons, unfamiliarity with the Canadian health system, and limited health literacy.¹⁰

The 2003 International Adult Literacy and Life Skills Survey (IALSS) found that 60% of immigrants lacked sufficient literacy skills to cope with the demands of life and work in today’s complex society as compared to 37% of Canadians.¹¹ The Canadian Public Health Association (CPHA) recommends that improvements in health literacy are critical to achieving positive health outcomes among immigrants and reducing health disparities.¹²

Oral health literacy is an important determinant of oral health^13,14 and a potential pathway to reduce oral health disparities.^15-17 Oral health literacy refers to the “degree to which individuals have the capacity to obtain, process, and understand basic health information and services needed to make oral health related decisions.”¹⁸ Atchinson et al. reported that immigrants have lower oral health literacy as compared to non-immigrants.¹⁹ Studies have shown that oral health literacy is associated with 1) poor oral health knowledge^20-22 , 2) poor oral health behaviours^23-25 , 3) less dental services utilization^26,27 , and 4) poor oral health status^28-32 . Ueno et al. demonstrated a significant relationship between the low level of oral health literacy, poor oral health behaviours, and poor oral hygiene status.²⁴

Dental plaque (a sticky layer containing bacteria), if not managed at an early stage, may lead to dental caries, periodontitis, oral infections, tooth loss or even contribute to other systemic diseases such as diabetes, cardiovascular diseases, and bacterial pneumonia.³³ Prevention and management of oral diseases are critically dependent upon one’s daily oral hygiene self-care behaviour, healthy dietary intake, and regular dental visits. Nevertheless, elementary oral hygiene self-care behaviour is often not adequately practiced primarily due to lack of awareness of its importance.³⁴

In light of the prevalence of low oral health literacy among vulnerable groups in the United States, several documents such as the Surgeon General’s report³⁵ , the National Institute of Dental and Craniofacial Research’s report¹⁴ , two reports by the Institute of Medicine, and the American Dental Association’s health dentistry action plan^36-38 have recommended that community-wide effective oral health literacy interventions are needed to raise public awareness of the causes and preventive measures of oral diseases.³⁹

Evidence from the US and Australia has shown that community-based oral health literacy interventions have the potential to reduce risk factors for oral diseases among Indigenous peoples³⁹ and seniors²⁴ . Although the field of oral health literacy has advanced in other developed countries, minimal oral health literacy related research^7,40,42 has been conducted in Canada. The scarcity of research on oral health literacy interventions among immigrants lent urgency to the present study.

Specific objective

The specific objective of this study was to evaluate whether the “Safeguard Your Smile” (SYS) oral health literacy intervention would be effective in promoting positive oral hygiene self-care behaviour among Punjabi immigrants. The researchers hypothesized that the SYS would improve oral health literacy and oral health (gingivitis) among intervention participants compared to a non-intervention control group.

Safeguard Your Smile intervention

A detailed developmental process of the SYS intervention has been described by the research team in a previous publication. In brief, the “Behavior Change Wheel” method was used to develop an oral hygiene self-care behavioural intervention for adult Punjabi immigrants with low oral health literacy. The SYS intervention comprised 5 components:

• 1) Reviewing a photonovel specifically designed for this intervention in partnership with Punjabi community participants to understand the risk factors of dental plaque and gingivitis as well as the benefits and risks of action or inaction of oral hygiene self-care behaviour on oral and general health.

• 2) Demonstrating the adequate tools and skills of toothbrushing, flossing, and tongue cleaning (frequency, duration, and technique) on a dentoform and employing the “teach back” technique to ensure it is well understood by the participants.

• 3) Encouraging participants to make a concrete plan specifying when, where, and how they would perform the daily routine of oral hygiene self-care and, in case they missed it, identifying their coping plan. Furthermore, participants were encouraged to identify their preferred environmental prompt/cue that could act as a reminder to perform their daily oral hygiene self-care routine, e.g., particular time of day, activity or technologies such as mobile phone alerts. Each participant was advised to register their individual concrete plan and preferred cue on the last page of the photonovel provided to them.

• 4) Encouraging participants to track the progress of their oral hygiene self-care routine daily on the provided calendar at the back of the photonovel for a complete 3 months after the intervention.

• 5) Follow-up by the lead researcher (through phone calls to each participant of the intervention group) once a month for reinforcement of their behaviour.

METHODS

Study design

This study used a parallel-group, non-blinded randomized controlled trial design. The 2-by-2 repeated measures design consisted of 2 groups of participants—one group (intervention) received the SYS intervention; the other group (control) received a conventional English language oral hygiene self-care pamphlet. Each participant was measured once at baseline and again 3 months after the SYS intervention. The goal was to compare the change across time in the intervention group to the change across time in the control group.

Ethical approval

The randomized clinical trial was reviewed and approved by the “Comité d’éthique de la Recherche en Santé” (i.e., the ethics review board of the Université de Montreal) and was registered at www.clinicaltrials.gov (Clinical Trial number: NCT02521155). As an incentive, the study participants received a soft toothbrush, dental floss, and fluoride toothpaste (having 0.254% sodium fluoride).

Study participants

P articipants were recruited from Montreal metropolitan areas with a dense population of Punjabi immigrants through a variety of methods, such as referrals from the members of our community partner organization, word of mouth, visits to Punjabi community temples, community centres, and grocery stores. To be eligible, participants had to meet the following inclusion criteria: 1) Punjabi immigrants who were residing in Montreal, 2) between the ages of 18 and 60 years, 3) in good general health, and 4) gave written informed consent. Exclusion criteria were 1) non-permanent residents, 2) use of orthodontic appliances, 3) self-reporting of presence of any disease of soft/hard oral tissues (e.g., advanced periodontitis); any systemic diseases (e.g., diabetes); and intake of medications such as anticonvulsants, calcium channel blockers, and chemotherapy.

Sample size

Calculation of the study sample size was based on estimates from a previous study by Hjertsted et al.²³ Experimental group plaque index (mean±sd): pre 0.36±0.20; post: 0.28±0.21 change = 0.08. Control group plaque index (mean±sd): pre 0.36±0.20; post 0.34±0.21 change = 0.02 control group. The correlation between measurement pairs was estimated at 0.8. Sample size estimation, based on a test for 2 groups of pre-post scores, was calculated as n = 70 for each group for an effect size = 0.45, with a power of 80% and alpha = 0.05 using a 2-sided t-test.

Variables

The independent variable was the group (intervention versus control). Dependent variables were oral health literacy (OHL), oral hygiene self-care knowledge, oral hygiene self-care behaviour, plaque index (PI), and gingival index (GI). Additionally, age due to significant differences between the control and intervention group and language of the questionnaire were considered covariates. Variables were measured using the following instruments.

Two-Stage Rapid Estimate of Adult Literacy in Dentistry

Each participant’s oral health literacy levels (both intervention and control groups) were measured using the Two-Stage Rapid Estimate of Adult Literacy in Dentistry (TS-REALD).⁴³ TS-REALD is a validated word recognition routing test in which participants are asked to read a list of 5 dental words aloud and 1 point is given for the correct pronunciation. This test categorizes the participants depending on their scores into 3 groups for further testing: 1) low literacy stage-2 (4-word test); 2) average literacy stage-2 (6-word test); and high literacy stage-2 (3-word test). The score from the routing test is added to the stage-2 score to produce the raw score. This raw score is translated into a scaled score by using the scaled score translational table that had been derived using psychometric testing.^41,43

Loe and Silness plaque and gingival indices

Using the Loe and Silness plaque index, which is a simple and non-invasive method⁴⁴ , the deposits of dental plaque for each participant were assessed. Participants were asked to chew a harmless dental plaque disclosing tablet and let it mix with their saliva, swish it for 30 seconds, spit it out, and rinse with water. The red colour of the disclosing tablet remaining on the teeth made deposits of plaque visible and facilitated assessment of where dental plaque was overlooked while brushing. The dental plaque disclosing tablets (GUM Red-Cote) were bought from the dental store at the Université de Montr é al. They contain medicinal ingredient DC Red 28 and the following non-medicinal ingredients: cherry flavouring, dextrose/malt dextrose blend, FD&C Blue #1, magnesium stearate, mannitol powder, and sodium saccharin.

Dental plaque index scores were assessed using a sterilized mouth mirror and the Loe and Silness index only on the 6 Ramfjord teeth (16, 12, 24, 36, 32, 44 on proximal, buccal, and lingual sides). A score of 0 = no dental plaque seen in the gingival area; a score of 1 = dental plaque present on the free gingival margin; a score of 2 = moderate accumulation of dental plaque at the gingival margin seen by the naked eye; and a score of 3 = abundant dental plaque in the gingival margin. Using a blunt dental probe and mouth mirror, researchers used the Loe and Silness gingival index to assess gingivitis. A score of 0 = no gingival inflammation; 1 = mild inflammation or slight change in colour of gingiva; 2 = moderate inflammation or moderate glazing, redness, edema and hypertrophy, tendency to bleed; and a score of 3 = severe inflammation, marked redness and hypertrophy, tendency to spontaneous bleeding.

Self-administered questionnaire

The self-administered questionnaire included items to capture sociodemographic information, oral hygiene self-care related knowledge and skills, and oral hygiene self-care behaviour (frequency, duration, and adequate technique). This questionnaire was used to measure both pre- and post-intervention oral hygiene self-care knowledge and oral hygiene self-care behaviour for both intervention and control groups. This questionnaire was translated into the Punjabi language and was provided to the participants who could not read or write in English.

Procedure

After recruitment and obtaining free and informed consent, 140 participants were randomly assigned to the experimental or control group using a computer-generated random sequence provided by a statistician at the Université de Montr é al, Canada. For data recording purposes, the intervention group participants were invited in small groups (3 to 4 participants) to one of the participant’s homes or to a suitable, quiet place mutually agreed upon by the participants. The lead researcher (NK) then provided a one-hour SYS intervention to the intervention group participants and gave a conventional pamphlet to the control group. NK ensured that all 5 components of the intervention were delivered, the one-hour time allotted for the intervention was respected, and that all questions and concerns of participants regarding the intervention were addressed. At post-intervention (i.e., after 3 months) the outcome measures were once again assessed. As shown in Figure 1, the equipment required during the intervention included the photonovel, a pamphlet, a dentoform, a long brush and, for the dental plaque examination, a lab coat, surgical gloves, sterilized mouth mirror, disclosing tablet, mask, and an examination light. A schematic of our research study is presented in Figure 2.

Figure 1.

Equipment used during SYS intervention

Statistical analysis

Prior to the main data analysis, a consistency check of baseline characteristics of both groups was conducted by crosstabulation. The distribution of socioeconomic characteristics such as age, gender, income, education level, occupational status, and insurance status across intervention and control groups was tested using the Chi-squared test for contingency table. To ensure the validity of the Chi-squared test, the variables were regrouped into categories (income, education, and occupational status) having less than 5 entries.

In order to test the effect of the intervention on oral hygiene self-care knowledge and oral hygiene self-care behaviour, the scores of the number of correct answers given by the participants on the self-administered questionnaire used pre- and post-intervention were aggregated. The study involved 2 independent factors: 1) within subject time (i.e., measurements before and after intervention) and 2) assigned group membership (i.e., intervention and control group).

We employed a linear mixed model repeated measure (LMMRM) by incorporating the variables for group (intervention vs control), time (pre- and post-intervention), the interaction term between time and group, age, and language of self-administered questionnaire if deemed appropriate.

A sensitivity analysis was performed using the Worst Outcome Carried Forward (WOCF) to handle study drop outs and unanswered questionnaire items.⁴⁵ The WOCF in this study consisted of using the pre-intervention values measured as observed data in the post-intervention. This strategy ensures that, even if the data is not missing at random, our results are robust to the worst-case scenario.

Figure 2.

Schematic of our research study

RESULTS

Sample characteristics

Initially 140 participants were recruited and consented to participate in the study. However, 21 people (15%) dropped out between pre-test and post-test primarily due to reasons such as work schedules, lack of interest or unavailability. All participants were Punjabi immigrants who reported being born in Punjab and confirmed the Punjabi language as their mother tongue. More than half (60%) of the participants were female, and the age of most participants (46.4%) ranged between 32 and 45 years. The education level reported by 37.7% of participants was a college/technical education; 26.8% reported having completed a university education. Almost 63.6% were full-time workers (including 14.3% who were self-employed), 5% worked part time, 1.4% were occasional workers, 22.1% were homemakers, and only 2.9% reported being out of work. In total, 72.9% of participants reported having no dental insurance, 24.3% had insurance through their workplace, and 2.9% had private insurance. Participants randomized into intervention and control groups differed as a function of age since females in the age group 32 to 45 years were over-represented in the intervention group compared to the control group.

Randomization check

Table 1 illustrates the socioeconomic characteristics of 140 participants (those who completed the intervention as well as the dropouts). Both intervention and control groups were homogenous since no significant differences were found at baseline and post-intervention except for age, which was significantly different between the control and intervention groups ( p <0.01).

Table 2 shows the baseline outcomes measures of the intervention and control groups. Although the p value of the gingival index is less than 0.05, this apparent difference has no clinical relevance.

Linear mixed model for repeated measures

Table 3 illustrates the differences between pre- and post-intervention measurements in the control group (first column), as well as differences between the intervention and control groups at pre-intervention (second column). The third column demonstrates group differences at post-intervention. The significant p values ( p <0.0001) in the third column suggest that the SYS intervention was effective.

In Table 3, the interaction term in the linear mixed model can be interpreted as the effect of the SYS intervention group versus the control group on the post-intervention outcome measures. Here, for both oral hygiene self-care knowledge and oral hygiene self-care behaviour, the participants who received SYS answered correctly on average 3.57 (95% CI: 2.88 to 4.26) and 3.10 (95% CI: 2.5 to 3.69) questions, respectively, more than those who received the conventional pamphlet. Furthermore, in the clinically measured plaque and gingival indices, the intervention group showed a change of 0.93 (95% CI: –1.04 to –0.81) and 0.93 (–1.06 to –0.80) in their plaque and gingival index scores, respectively, and there was an increase in the OHL scores of 5.10 (3.85 to 6.34) points.

The effect of the SYS intervention was far more positive as compared to the control group effect. It should be noted that the WOCF imputation model also yielded the positive effect of the SYS intervention, which remained highly significant across all 5 outcomes (Figure 3).

Table 1.

Socioeconomic characteristics of participants

Characteristics	Control group N = 70 (%)	Intervention group N = 70 (%)	P value
Age in years 18 to 31 32 to 45 46 to 60	19 (27.1) 25 (35.7) 26 (37.1)	18 (25.7) 40 (57.1) 12 (17.1)	0.013
Gender Female Male	36 (51.4) 34 (48.6)	48 (68.6) 22 (31.4)	0.057
Annual income $0 to $49,999 $50,000 to $89,999 $90,000+ $ Unknown	33 (24.3) 15 (22.9) 5 (14.3) 15 (7.1)	40 (18.6) 12 (35.7) 4 (11.4) 14 (5.7)	0.704
Education level College/technical High school or less University	25 (35.7) 24 (34.2) 21 (30)	28 (40) 25 (35.7) 17 (24.3)	0.694
Occupation status Full-time worker Part-time worker Self-employed/part time	35 (50) 20 (17.1) 15 (1.4)	34 (48.6) 22 (27.1) 14 (24.3)	0.930
Insurance status Insured Not insured	51 (72.9) 19 (27.1)	51 (72.9) 19 (27.1)	1.000

^*χ²,p < 0.01

DISCUSSION

This study evaluated the effectiveness of the SYS, an oral health literacy intervention aimed to promote positive oral hygiene self-care behaviour among Punjabi immigrants. Statistically significant positive differences between the 2 groups (intervention and control) for the dependent variables of oral hygiene self-care knowledge and behaviour, oral health literacy, and plaque and gingival indices were observed. To our knowledge, this study is the first attempt to evaluate effectiveness of an oral health literacy intervention promoting oral hygiene behaviour among Punjabi immigrants.

The findings of our study are partially in line with a previous study done by Mills et al., which demonstrated that a series of educational sessions can improve oral health knowledge and self-efficacy.⁴¹ However, their study’s sample size was quite small (15 participants), therefore their results cannot be generalized. Their study also lacked evidence to show success of their educational interventions in achieving sustainable oral health related behaviour change.⁴¹ Another pre-post study was conducted among 67 older, primarily Caucasian adults, which employed a community-based educational intervention involving multiple interactions that significantly and positively affected oral health literacy and oral hygiene status among older adults.²³ However, the theoretical underpinning of these previous oral health literacy interventions was unclear. Thus, our study differs from both previous studies since it implemented an oral health literacy intervention based on the behaviour change wheel model and evaluated its effectiveness among a much larger sample size (140 Punjabi immigrants) than the previous studies.

Figure 3.

Effects of the SYS intervention on oral hygiene self-care knowledge, oral hygiene self-care behaviour, OHL scores, gingival indices, and plaque indices

Table 2.

Baseline characteristics of outcome measures

Outcome measures	Control group (N = 70)	Intervention group (N = 70)	P value
Oral hygiene self-care knowledge
Mean (SD)	2.843 (1.528)	2.4 (1.511)	0.087
Median	3	2
Interquartile range	2 to 4	2 to 4
Oral hygiene self-care behaviour
Mean (SD)	2.417 (1.441)	2.643(1.642)	0.051
Median	2	3
Interquartile range	1 to 4	1 to 4
OHL score
Mean (SD)	32.21 (7.190)	35.06 (7.615)	0.050
Median	31.00	35.00
Interquartile range	31.00 to 38.00	27.00 to 40.25
Plaque index
Mean (SD)	1.324 (0.488)	1.353 (0.347)	0.069
Median	1.33	1.33
Interquartile range	1.000 to 1.570	1.160 to 1.500
Gingival index
Mean (SD)	0.958 (0.664)	1.054 (0.560)	0.036
Median	0.935	1.19
Interquartile range	0.3775 to 1.442	0.520 to 1.370

Interestingly, beyond the effect of the SYS on the intervention group, this study found that even the control intervention had a beneficial effect on oral health self-care knowledge, oral health self-care behaviour, and oral health literacy scores of the control group participants. This improvement may be due to the oral hygiene self-care related information provided in the conventional pamphlet.

A m ajor strength of this study, which separates it from the others, is that the outcomes were measured both clinically (plaque and gingival indices before and after intervention) and through self-reported questionnaires measuring oral health literacy, oral hygiene self-care knowledge and behaviour. One of the limitations of the study was that the oral health literacy measurement tool utilized did not capture all dimensions of oral health literacy levels, given that it is primarily a word recognition assessment tool which cannot differentiate between lack of background knowledge in oral health related domains, lack of familiarity with language and types of materials used or cultural differences in approaches to oral health care.

Future oral health literacy intervention studies should develop and employ a more precise measurement tool that captures all dimensions of oral health literacy. In addition, future studies should implement and evaluate such interventions in other community groups. Furthermore, rigorous evaluations of the cost-effectiveness of these interventions to optimize oral health literacy intervention procedures for different ethnic, age, and gender groups are needed. The effectiveness of behaviour change interventions is often limited in the sense that, after the intervention is over, the acquired behaviours are generally lost in the long term. Therefore, the authors recommend that future research consider incorporating technology elements in addition to human guidance into interventions, ensuring sustainable oral health related behavioral changes. For example, mobile phone reminders can offer support through persuasion and contribute to enhancing long-term sustainability of behaviour.

Finally, this study found that most respondents received oral hygiene self-care information from their medical care providers. Thus, it is recommended that future research studies explore the effectiveness of oral health literacy interventions that improve oral health by integrating oral health literacy interventions into primary health care settings.

CONCLUSION

The field of oral health literacy research is still waiting for the development of a new oral health literacy instrument capable of capturing all dimensions of oral health literacy. Despite its limitations, the novel attempt of this research study to implement and evaluate a theoretically grounded and community-based oral health literacy intervention is a contribution to the scarce literature on oral health literacy interventions among immigrants. The present study provides evidence that oral health literacy interventions such as the SYS can successfully promote positive oral hygiene self-care behaviour among immigrants with low oral health literacy levels.

Table 3.

Linear mixed model repeated measure analysis

Fixed effects
Outcome variable	Time pointa (Pre versus post) Control group		Randomized group assignmentb (Control versus intervention)		Randomized group assignment Interaction with timec
	Effect (95% CI)	Significance	Effect (95% CI)	Significance	Effect (95% CI)	Significance
Oral hygiene self-care knowledge	0.82 (0.34 to 1.31)	0.0008	0.27 (-0.27 to 0.81)	0.8365	3.57 (2.88 to 4.26)	<0.0001
Oral hygiene self-care behaviour	0.48 (0.07 to 0.90)	0.0216	-0.23 (-0.75 to 0.30)	0.8006	3.10 (2.50 to 3.69)	<0.0001
OHL score	1.41 (0.53 to 2.29)	0.0014	0.66 (-1.93 to 3.25)	0.692	5.10 (3.85 to 6.34)	<0.0001
Plaque index	-0.07 (-0.21 to 0.27)	0.0962	0.04 (-0.08 to 0.17)	0.5171	-0.93 (-1.04 to -0.81)	<0.0001
Gingival index	-0.01 (-0.72 to 0.29)	0.1889	0.11 (-0.07 to 0.29)	0.7814	-0.93 (-1.06 to -0.80)	<0.0001

^aThis can be interpreted as the effect of control measurement (pre and post) on the outcome of interest.^bThis can be interpreted as the effect of random group assignment on the pre-intervention measurement on the outcome of interest.^cThis can be interpreted as the effect of actual intervention versus control intervention in the post-intervention measurement on the outcome of interest.

CONFLICT OF INTEREST

The authors have declared no conflicts of interest.