Effectiveness of oral health education in children – a systematic review of current evidence (2005–2011)

Abstract

Background: So that resources and manpower are allocated in a way of most benefit to the population, systematic review of available evidence on the effectiveness of programmes and interventions is required. Objectives: To assess the quality of evidence presented in studies carried out to investigate the effectiveness of oral health education in children. Methods: The MEDLINE (PubMed) bibliographic database was searched for English-language articles published from 2005 to 2011. Fifty-five articles were identified by the literature search, and the relevance of each article was determined by examining the title and the abstract. Sixteen original research studies met the inclusion criteria. These articles were read in full and scored independently by two reviewers, with scoring based on predetermined criteria. Articles scoring less than 10 were excluded from the study. For each paper that achieved a validity score of more than 10 (n = 11), data concerning the objectives of the intervention, the types and numbers of participants and the outcomes were extracted from the article. Considering the absence of homogeneity among the articles (as a result of variation in the age of subjects, type of intervention and outcome measures) quantitative analysis was not conducted. The publications were grouped based on their outcome measures: (i) plaque and gingival health; (ii) caries incidence; (iii) knowledge, attitude and oral health-related behaviour; and (iv) toothbrushing skills. Results: The results of this analysis suggest that further efforts are required to synthesise, systematically, current information about dental health education, along with the maintenance of rigorous scientific standards in research.

INTRODUCTION

Since the 1900s, dental health education has been considered an important and integral part of dental health services and has been delivered to individuals and groups in settings such as dental practice, schools, the workplace, and day-care and residential settings for older adults. The population as a whole has also been targeted using mass-media campaigns. The educational interventions used have varied considerably, from the simple provision of information to the use of complex programmes involving psychological and behaviour-change strategies. The goals of the interventions have also been broad, so that knowledge, attitudes, intentions, beliefs, behaviours, use of dental services and oral health status have all been targeted for change. These efforts are testimony to dentistry’s long-standing, and perhaps pioneering, concern with the prevention of oral disease via changes in knowledge, attitudes and behaviours and the adoption of healthier lifestyles¹.

Since 2000, substantial literature has emerged describing studies purporting to evaluate the effectiveness of various types and combinations of educational and behaviour-modification techniques. Brown reviewed 57 such studies published between 1982 and 1992 and concluded that dental health education can result in improvements in dental health behaviours and in objective measures of oral health status but was less effective in changing attitudes and knowledge². Perhaps the most important issue is the quality of the designs used in the studies themselves. In order to avoid bias, error and various threats to validity, only the results of randomised controlled trials are usually included in systematic reviews. Locker and Kay reviewed the literature and concluded that the quality of the evidence pertaining to the effectiveness of dental health education is poor¹.

Dental health education can be delivered to individuals and groups in settings such as dental practice, schools, the workplace and day-care and residential settings for older adults. The importance of giving health education to children is that they are at an early point in their health career. Also, educating children can help us reach their families and community members. Logically, this provides a prime opportunity for influencing attitudes and behaviours at a formative stage. There is debate about the effectiveness of health education and, as a result, evidence-based information should be made available. Hence, this study was conducted with the objective of assessing the quality of the evidence presented in studies, published from 2005 to 2011, on the effectiveness of oral health education in children.

METHODOLOGY

Types of studies

We aimed to identify all randomised controlled trials educating children about oral health. The unit of randomisation was defined as the individual or the group (school, school class, etc.), as long as this was taken into account in the analysis.

Types of interventions

The following intervention groups were considered:

• •Health education given using any method
• •Demonstration of brushing technique.

Types of outcome measurements:

• •Improvement in knowledge, attitude and practices regarding oral health
• •Dental plaque and gingival bleeding
• •Caries incidence
• •Toothbrushing skills.

Search strategy

We searched the MEDLINE database (through PubMed) for articles published between 2005 and 2011 and only publications in the English language were considered. All records electronically identified were scanned, by both review authors, according to title, abstract (when available) and/or keywords, and the full text of all reports considered potentially relevant was obtained.

The subject headings used were ‘dental health education’, ‘oral health promotion’, ‘children’ and ‘effectiveness’. The reference lists from the papers retrieved by this search were reviewed and any relevant references were followed up. The studies described in the papers resulting from this search were subjected to a preliminary review and the following were excluded: reviews, case reports or editorials; studies describing interventions that were not primarily dental health education; and papers reporting an intervention described in another paper. The selected publications were grouped into the following categories according to the main outcome measure used: (i) studies focusing on plaque and gingival health; (ii) studies aiming to reduce caries levels; (iii) studies aiming to improve knowledge and attitudes; and (iv) studies focusing on improving toothbrushing skills.

Study selection

The baseline searches were carried out by two review authors. Selection of papers on the basis of the title, keywords and abstract, and decisions about eligibility, were carried out independently by both review authors. Reports that were obviously irrelevant (according to study design/duration, participants or interventions/comparisons) were not considered. The full text of every article considered for inclusion was obtained. If the information relevant to the inclusion criteria was not available in the abstract or if the title was relevant but the abstract was not available, the full text of the report was obtained. All information and data recording were carried out independently and there were no disagreements between the two review authors (Figure 1).

Figure 1.

Flowchart depicting the study design with the reasons for exclusion.

Each study was reviewed and critically appraised by two independent researchers according to a set of validity criteria (Table 1). If all criteria were met, a maximum score of 19 was achieved. A qualitative review of the objectives of each investigation, the nature of the intervention, the types and numbers of participants and the outcome of the intervention was recorded. Studies were included in this review if they achieved a validity score of 10. As the focus of this systematic review was health education, all the studies were variable in respect to outcome measures, control groups were not necessarily used, randomisation was not optimal and hence a lower score of 10 was considered for inclusion of articles.

Table 1.

Criteria used to assess the studies selected

1	Randomisation done?
2	Type of randomisation mentioned
3	Blinding
4	Control group present
5	Description of the trial design
6	Sample size estimation
7	Inclusion and exclusion criteria
8	Statistical analysis
9	Research aims defined?
10	Details of drop-outs
11	‘n’ for each group
12	Intervention and control equivalence
13	Details of intervention
14	Outcome measures defined
15	Outcome measures objectively measured
16	Means and SD of baseline and final test
17	Follow-up defined
18	Informed consent obtained
19	Ethical consent obtained

SD, standard deviation.

Fifty-five publications were identified based on the title and the abstract. Of those, 16 articles fulfilled our criteria. The articles excluded3., 4., 5., 6., 7., 8., 9., 10., 11., 12., 13., 14., 15., 16., 17., 18., 19., 20., 21., 22., 23., 24., 25., 26., 27., 28., 29., 30., 31., 32., 33., 34. included parents, caregivers and schoolteachers also in health education. On scoring these 16 articles based on the criteria we used to assess the quality of the randomised trials, five received a score of lower than 10 and hence were excluded. The systematic review of 11 articles was conducted (Table 2).

Table 2b.

Criteria with the scores of the articles included

No.	Author	Research aims defined	Details of drop-outs	‘n’ for each group	Intervention and control group equivalent	Details of the intervention	Outcome measures defined	Outcome measures objectively measured	Mean and SD of baseline and final	Follow-up defined	Informed consent	Ethical approval
1	Yazdani et al.35	✓	✓	✓	×	✓	✓	✓	✓	✓	✓	✓
2	Paulo Frazao et al.38	✓	✓	×	×	✓	×	✓	×	✓	✓	✓
3	Arikan et al.36	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
4	Saied-Moallemi et al.37	✓	×	✓	✓	✓	✓	✓	✓	✓	✓	✓
5	Shenoy et al.42	✓	✓	✓	✓	✓	✓	✓	✓	✓	×	✓
6	Reinhardt et al.39	✓	×	✓	×	✓	✓	×	×	✓	✓	✓
7	Livny et al.40	✓	✓	✓	×	✓	✓	×	✓	✓	✓	✓
8	Tolvanen et al.41	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
9	Zanin et al43	✓	✓	✓	✓	✓	✓	✓	×	✓	✓	✓
10	Tai et al.44	✓	✓	✓	×	✓	✓	✓	✓	✓	✓	✓
11	de Farias et al.45	✓	×	✓	×	✓	✓	✓	✓	✓	✓	✓

Table 2a.

Criteria with the scores of the articles included

No.	Author	Year	Study duration	Randomisation	Type of randomisation	Blinding	Control group	Description of trial design	Sample size estimation	Inclusion and exclusion criteria defined	Statistical analysis
1	Yazdani et al.35	2009	12 weeks	✓	✓	✓	✓	✓	✓	×	✓
2	Frazao38	2011	18 months	✓		✓	✓	×	×	×	✓
3	Arikan et al.36	2007	9 months	×	×	✓	×	✓	×	✓	✓
4	Saied-Moallemi et al.37	2009	3 months	✓	✓	✓	✓	✓	✓	×	✓
5	Reinhardt et al.39	2009	7 days	×	×	×	×	×	×	✓	✓
6	Shenoy et al.42	2010	36 weeks	×	×	×	✓	×	✓	✓	✓
7	Livny et al.40	2008	4 months	×	×	×	×	×	✓	✓	✓
8	Tolvanen et al.41	2009	3.4 years	✓	✓	×	✓	✓	✓	✓	✓
9	Zanin et al.43	2007	15 months	✓	×	✓	✓	×	✓	✓	✓
10	Tai et al.44	2009	3 years	✓	✓	✓	✓	✓	✓	✓	✓
11	de Farias et al.45	2009	4 months	✓	×	×	✓	✓	×	×	✓

RESULTS

Table 3 shows the distribution of these papers according to the main outcome of the intervention for each group. The majority of these studies assessed the effects of educational interventions on knowledge and attitudes or on plaque and gingival health.

Table 3.

Details of the studies included with their main findings

Category	Number of papers included	Types of intervention	Papers showing positive effect	Papers showing no effect	Conclusion
Plaque removal/gingival health	3	Leaflets, videotapes, verbal, written, puzzles, supervised toothbrushing	3	0	Short-term effectiveness of school-based intervention in improving oral cleanliness and gingival health. Verbal oral-health education more effective than written
Caries	1	Demonstration of toothbrushing	1	0	Toothbrushing is effective in vulnerable groups
Toothbrushing skills	2	Demonstration of toothbrushing	2		Tutoring by older peers and general health educators can also demonstrate the ignificant improvement in brushing skills
Knowledge, attitude and behaviours	1	Health education through videos, plays, posters	1	1 (attitude and knowledge)	Children improved oral health-related behaviours but not attitude and knowledge
Combination	2 (KAB and plaque) 1 (caries and plaque) 1 (caries, improving oral hygiene, positive oral health-related behaviour)	Various methods of health-education lectures, group discussions, puppet plays, supervised toothbrushing	4		Oral health education programmes conducted at 3-week intervals were more effective than those conducted at 6-week intervals in improving oral health knowledge

KAB, Knowledge, Attitude and Behaviors.

Improvement in plaque and gingival health

Programmes that aimed to reduce plaque levels and improve gingival health were successful, although the positive effects were only short term. However, reductions in plaque and gingival bleeding scores, although statistically significant, were usually small and of unknown clinical significance. Yazdani et al.³⁵ reported a positive outcome for oral cleanliness, which was 58% (P < 0.001) of the students in the leaflet group, 37% (P < 0.001) in the videotape group and 10% of controls. Corresponding values for gingival health were 72% (P < 0.001), 64% (P < 0.001) and 30%. For oral cleanliness, Number needed to Treat (NNT) was 2 in the leaflet group and 3 in the videotape group; for gingival bleeding, NNT in both groups was 3. While Arikan et al.³⁶ observed that the difference was non-significant at baseline and in 3 months period in both education groups (P > 0.05) and in 6 and 9 months control periods the difference in plaque index scores was non- significant in both appliance groups (P > 0.05) while the difference between the education groups was significant (P < 0.05). Saied-Moallemi et al.³⁷ in the Genaralised Estimating Equation (GEE) models, confirmed a strong intervention effect on healthy gingiva in groups in which parents were involved, namely the parental-aid group [odds ratio (OR) = 7.7, 95% confidence interval (95% CI): 2.2–27.7] and the combined group (OR = 6.6, 95% CI: 2.0–22.1). In all intervention groups, more girls than boys achieved healthy gingiva (OR = 2.5–2.6).

Reduction in caries incidence

One study relating to dental caries showed a reduction in caries incidence in the experimental group. Frazao³⁸ recorded enamel and dentine caries on buccal, occlusal and lingual surfaces of permanent molars during the 18-month follow-up of professional cross-brushing on the surfaces of first permanent molars, rendered by a specially trained dental assistant five times per year. Exposure time of surfaces was calculated and the incidence density ratio was estimated using the Poisson regression model. A difference of 21.6 lesions per 1,000 children between control and test groups was observed. Among boys (whose caries risk was higher compared with girls), the incidence density was 50% lower in the test group (P = 0.016).

Improvement of toothbrushing skills

Two studies included aimed to improve the toothbrushing skills of children; in one study, older peers or students studying in higher standards were used and in the other the hygienist demonstrated the brushing technique. Reinhardt et al.³⁹ reported that before the instruction, 10 first-graders employed a circular toothbrushing technique; after instruction, this figure trebled. Statistical analysis using McNemar’s test showed a highly significant difference (P = 0.0001). Similarly, Livny et al.⁴⁰ reported that at baseline 92% of the children brushed the labial surfaces of their front teeth but only 8% brushed the inner surfaces of their posterior teeth. Only 32% brushed the occlusal surfaces. These levels increased significantly after 4 months: 98% now brushed the labial surfaces; 43% brushed the inner surfaces of their posterior teeth; and 87% brushed the occlusal surfaces (P < 0.001). The average number of dental ‘areas’ brushed had increased (among the eight areas recorded) from 2.8 to 5.7 (P < 0.0001).

Improvement in knowledge, attitudes and oral hygiene behaviours

The analysis indicated that knowledge and attitudes could be improved through dental health education, with one study showing positive effects. Tolvanen et al.⁴¹ reported that children in the experimental group of the randomised controlled trial tended to improve their behaviour more than did those in the control group. Children in the experimental group (n = 250) were offered an individualised regimen for caries control, aiming to identify and eliminate those factors that had led to the presence of active caries. The authors concluded that the oral health-promotion programme can improve oral health-related behaviour but has less effect on improvement of knowledge and attitudes.

Combination

Programmes aimed at a combination of the outcomes also showed that short-term results were better and that a shorter follow-up time was more effective than a longer follow-up. Shenoy et al.⁴² studied the outcomes oral health knowledge and plaque and gingival scores and reported that reductions in plaque and gingival scores were highly significant in schools where the intervention was done, and were not influenced by the socio-economic status. When oral health knowledge was evaluated, highly significant changes were seen in schools which underwent intervention; these changes were more significant in schools receiving more frequent interventions. Zanin et al.⁴³ studied the outcomes in gingival and plaque scores and in decayed missing filled surfaces (dmfs) and Decayed Missing Filled Surfaces (DMFS) indices. The experimental group showed a statistically significant reduction in mean values for the two indices. The gingival and plaque scores showed better improvement in short-term evaluations but not in long-term evaluations. Regarding caries, in the control group, 23 new caries lesions could be detected in 40% of the children. Of the 12 children affected, two developed enamel caries and 10 developed caries in dentine. In the experimental group, eight new caries lesions could be detected in 6% of the children. Of the seven children affected, four developed enamel caries, one dentine caries and two developed both enamel and dentine caries. There was a statistical difference between control and experimental groups in relation to the percentage of children affected and the incidence of caries. Tai et al.⁴⁴ studied caries, gingival health and oral hygiene habit outcomes. The 3-year net mean DMFS increment score was 0.22 in the intervention schools and 0.35 in the control schools (P < 0.013). After 3 years, statistically significant differences in mean plaque (P < 0.013) and sulcus bleeding (P < 0.005) increment scores were found between the two groups. Statistically significantly higher scores were observed in restorations received and sealants placed, and a lower score in untreated dental caries, in children from the intervention group than in the control group after 3 years (P < 0.01). In addition, more children in the intervention schools adopted regular oral health behavioural practices, such as brushing their teeth at least twice a day, visiting the dentist within the past calendar year and using fluoride toothpaste. de Farias et al.⁴⁵ observed the outcomes knowledge, attitude and practices regarding oral health and plaque and gingiva scores. Final plaque scores (P = 0.014, OR = 0.46, CI = 0.24–0.86) and gingival bleeding (P = 0.013, OR = 0.49, CI = 0.28–0.90) indices decreased more in the experimental group. The experimental group also showed a statistically significant difference (P < 0.001) between the numbers of correct answers in the questionnaire after the education intervention. The authors concluded that contextualised educational activities in the school routine had positive effects on oral hygiene and the level of information about oral health, although the more informed individuals did not always practice better oral hygiene.

DISCUSSION

Before conclusions can be drawn from the results, it needs to be borne in mind that only one database was searched for this systematic review, only publications in the English language were considered and literature from conference proceedings and dissertations and unpublished literature was not searched for. The studies selected had different durations of follow-up, the age group of the study subjects was variable, the methods of health education were different and the health-education materials used were also different, so it was not possible to compare the studies quantitatively.

The main reasons for not considering quantitative analysis of the included studies were:

• •Varying lengths of follow-up
• •Variable age-groups of children
• •Inconsistent indices used as outcome measures
• •Insufficient data presented
• •Lack of control groups
• •Lack of objective outcome measures
• •Outcome measures not described or validated.

The main conclusion that can be drawn from this systematic review is that studies which have been conducted to investigate the effectiveness of oral health education in children do not have uniformity and no strict guidelines exist to conduct a randomised control trial with health education as the intervention. There are two main differences between health education as the intervention and other interventions. First, the outcome measure – knowledge and attitude – of the health education intervention cannot be measured quantitatively (and this makes comparison between studies difficult). Second, in other interventions the end points measured are in the form of mortality or morbidity, which are relatively clear-cut; however, these end points are not relevant for health education. Hence, the degree of change in the outcome (as well as its statistical significance) should be observed and reported. The environment and situation will always have an impact on the choices people make. Hence, considering only behavioural change as the ultimate goal of health education may be insufficient. Studies need to be conducted with an innovative focus of health education on the decision makers and policy makers, who can change the environment in which people live and develop their habits and who help to minimise or eliminate the risk-behaviours.

CONCLUSION

Very few systematic reviews have been conducted on the effectiveness of oral health education in children because of the variation in the study protocol used. Hence, an attempt was made to assess the quality of the literature related to health education as an intervention in children. The studies showed improvement in the plaque and gingival scores, but the results were short-lived; also, there was improvement in the knowledge of the subjects, but the attitude and behaviour did not improve proportionately. Very few studies were conducted to assess the incidence of dental caries after health education. Children showed significant improvement in toothbrushing skills when demonstration and supervision were provided. Hence, the limitations of this systematic review should be borne in mind before the results are used or extrapolated.

Acknowledgement

None.

Competing Interest

None.