Abstract
Objectives: To obtain basic data on dental caries and gingival status of students in Myanmar, and to identify related risk indicators, including socioeconomic conditions and oral health behaviours and habits. Study design: This cross-sectional study enrolled 537 fifth-grade students in Myanmar. Oral health behaviours and dietary patterns of students were assessed using questionnaires. Oral examinations were conducted to identify dental caries and gingivitis, and the oral samples were obtained to determine the bacteria levels in dental plaque. Results: The dental caries prevalence was 68.5%, with a mean number of decayed teeth of 2.07 ± 2.15. The prevalence of gingivitis was 98.9%, and the mean number of inflamed gingival areas in the anterior region was 16.2 ± 5.4. No significant differences were found between the sexes in terms of dental caries and gingivitis. Oral hygiene was significantly poorer, and levels of bacteria in dental plaque were significantly higher in boys than in girls. Multiple linear regression tests were used to analyse the association between risk indicators and dental caries and gingivitis. Tooth brushing frequency, a daily habit of mouth rinsing, dental visit experience, consumption of sugary snacks and oral hygiene status were significantly associated with dental caries. Mother’s occupation, tooth brushing frequency, consumption of sweet drinks, oral hygiene status and bacterial levels in dental plaque were significant predictors of gingivitis. Conclusions: Myanmar students had a high prevalence of dental caries and gingivitis. Socioeconomic condition, oral hygiene status and oral health behaviours were all determined to be significant risk indicators.
Key words: Dental caries, gingivitis, Myanmar, risk indicators, student
INTRODUCTION
Oral health is an integral component of general health, and a major determinant of the quality of life. One of the most common oral diseases is dental caries, which affects 60%–90% of children globally1. In some Asian countries, dental caries is widespread and has become a major public health problem2, 3. The high prevalence of dental caries may be associated with the frequent consumption of sweet foods, lack of adequate oral hygiene and accumulation of dental plaque, past experience of dental caries in the primary dentition, female sex, low socioeconomic status4, and inadequate utilisation of dental services5, 6. Dental caries and its associated pain can interfere greatly with a child’s daily life by causing a lack of sleep, affecting academic performance and resulting in missed school days, and posing an economic burden3.
Children also have various degrees of gingivitis, which may progress to periodontitis if not treated properly7. The aetiology of gingivitis is multifactorial and has been shown to be significantly associated with oral bacterial biofilms, as well as genetic, socioeconomic, demographic, iatrogenic and behavioural factors8. Gingivitis is a more innocuous condition compared with dental caries, and is rarely associated with obvious clinical signs and symptoms other than mild and intermittent gingival bleeding9. Microorganisms in dental plaque biofilms are the main aetiological factors for the initiation of gingival inflammation, but the host response also plays a major role10.
Several studies have been conducted to investigate sex-based differences in oral diseases across various age groups. The greater burden of dental caries experience in girls has been associated with earlier tooth eruption, more frequent snacking, hormonal or physiological differences, low concentration of IgA immunoglobulin and low salivary flow rate11. Oral hygiene care, and hormonal, physiological and behavioural differences between the sexes may all contribute to the higher risk for periodontal diseases12. Considering sex-based differences in the oral health status of students may improve prevention programmes and therapeutic approaches against oral diseases13.
While culturing on agar plates has served as the conventional method for enumeration of bacterial colony-forming units (CFU), the disadvantage in that a few days are required before the results can be obtained. Recently, a dielectrophoretic impedance measurement system has been developed for the rapid quantification of bacterial concentrations within 1 minute (Panasonic, Tokyo, Japan)14. Prior studies have also demonstrated a strong correlation with conventional culture methods15. The compact size of the apparatus and its portability also make it highly suitable for surveying large samples in field conditions.
Schools are a place of learning and present a unique opportunity for promoting the importance of oral health to students16. The lack of an adequate level of oral hygiene care results in dental caries and gingivitis, which can lead not only to the early loss of deciduous teeth and damage to the permanent successors, but can also have a significant adverse effect on psychological well-being and general health17. Prior studies have demonstrated the effectiveness of implementing school oral healthcare programmes that are aimed at promoting healthy oral care practices18.
Oral health promotion and oral health education are integral components of existing national health strategies in Myanmar19. Nevertheless, current efforts in dental public health-related activities remain insufficient. Moreover, there is a lack of annually collected data on oral health in schools in Myanmar. In particular, very limited data are available on the oral health status of school students during the mixed dentition stage. This is pertinent, as the early identification of risk indicators of oral diseases would allow dental professionals to formulate and enact appropriate preventive measures. Therefore, the objectives of the present study were to collect basic data on the clinical oral health status of school students in Myanmar, and to investigate associated risk indicators, including sex-based differences, socioeconomic condition of the parents, as well as the oral health behaviours and dietary patterns of students.
MATERIALS AND METHODS
Participants
The required sample size for this study was determined to be 362 students, after accounting for 80% power, a confidence level of 95%, and compensation for a 10% non-response rate. A previous study20 that was conducted in Japan, and also part of a school oral health promotion programme, was used to inform the sample size calculation. Two townships were randomly sampled from 34 townships in Yangon Region, Myanmar, using a computer-generated random sampling method. Similarly, four schools within these two townships were randomly sampled. After obtaining permission from the education authorities of the schools, written informed consent forms were obtained from the students and their parents or guardians.
All eligible fifth-grade students in these four schools (n = 569) participated in the study. The exclusion criteria were students who: (1) had systemic disease or neuromuscular dysfunction; (2) lacked parents’ permission; and (3) were not willing to participate in the study. A total of 537 participants (251 boys and 286 girls) completed the questionnaire survey and underwent a clinical oral examination. The overall response rate was 94.4%. This cross-sectional study was conducted from December 2017 to January 2018 as part of a school oral health promotion programme.
This study was approved by the ethical committee of the Department of Medical Research in Myanmar (approval no. Ethics/DMR/2017/064), University of Dental Medicine, Yangon and Tokyo Medical and Dental University (approval no. D2017-018). This study was conducted in full accordance with the Helsinki Declaration of the World Medical Association.
Questionnaire survey
The parents provided information on their occupational status. Questions regarding their occupational status were open-ended and categorised into five groups, such as government worker, professional, unskilled worker, merchant/seller, farmer, and dependent/unemployed. The students were asked to answer questions on their oral health behaviours, such as frequency of tooth brushing (‘less than once a day’, ‘once a day’, ‘twice a day’, and ‘more than twice a day’)21, daily mouth-rinsing habit (‘once a day’, ‘twice a day’, ‘thrice a day’, and ‘never’)22, dental visit over the last 12 months (‘once’, ‘twice’, ‘three times’, ‘four times’, ‘more than four times’, ‘no visit to dental clinic during the last 12 months’, and ‘never visited a dentist’), and reasons for a dental visit (pain or trouble with teeth, gums or mouth, follow-up treatment, routine dental check-up, don’t know)23. These standardised questionnaires had been previously validated21, 22, 23.
Self-administered questionnaires assessed the dietary habits of students with regards to the availability of various types of sugary snacks and sweet drinks in their school canteen or snack shop. The children were asked to answer questions on their daily consumption of at least one or more sweet snacks (‘eat’ or ‘don’t eat’), and sweet drinks (‘drink’ or ‘don’t drink’). Questionnaires were translated into Myanmar language, and the translated versions were assessed and revised by expert panels. The Myanmar versions were pretested on a convenience sample of 25% of the students in a pilot study. Test–retest reliability was performed 2 weeks later for reliability testing. Based on the feedback received, the final questionnaire was developed after minor revisions.
Clinical oral examination
A trained dentist evaluated the oral status of all students who were present on the day of examination. An artificial light, a mirror, and a community periodontal index probe [World Health Organisation (WHO)] were used in the oral examination. Dental caries were recorded using the decayed, filled teeth (dft), and decayed, missing and filled teeth (DMFT) indices, in accordance with WHO guidelines23.
The gingival status of 12 anterior teeth was evaluated using the papillary, marginal and attached gingiva (PMA) index24: 10 interdental papilla, 12 marginal gingivae and 12 attached gingivae were assessed. Only the gingivae of erupted teeth were examined; therefore, the total PMA index score was based on 34 gingival sites.
Oral hygiene status was evaluated using the simplified oral hygiene index (OHI-S). The simplified debris index (DI-S) and simplified calculus index (CI-S) were used for the assessment. The OHI-S score was calculated by adding the DI-S (0−3) and CI-S (0−3) scores25. Cronbach’s alpha coefficient was calculated to check the intra-examiner reliability of dental caries, OHI-S and PMA index. The values were excellent for dental caries (0.90), and good for OHI-S (0.76) and PMA (0.77).
Oral bacteria
Plaque samples were collected by the same investigator who performed the clinical examination. Using a sterilised cotton swab, a plaque sample was obtained from the cervical portion of the buccal surface of the maxillary left permanent first molar. The swab was moved three times from the mesial to the distal direction, and the same procedure was repeated after the swab was reversed. If the maxillary left permanent first molar was extracted or severely damaged by caries, the maxillary right permanent first molar was used as a substitute.
Bacteria within the plaque samples were quantified with a bacteria counter (Panasonic, Tokyo, Japan) over a duration of approximately 1 minute14. This bacteria inspection apparatus utilises dielectrophoretic impedance measurement (DEPIM), and quantitatively evaluates clinical samples from the oral cavity using high electrical conductivity and selective detection of biological cells based on their variability26 or species, combined with an antigen–antibody reaction27. The results were expressed as face icons representing the seven-level ranking system, and the numerical value was displayed on an LCD screen. The first permanent molar was selected as the index tooth for dental plaque sampling, due to the longer period of exposure in the oral cavity compared with the other permanent teeth28. Additionally, it has been widely documented that dental plaque deposits are heavier in the posterior regions29. The first permanent molar has also been previously established as an index tooth for the determination of OHI-S index scores25.
In the present study, bacteria were quantified as CFU/mL, and categorised as follows: Level 1 = under 105 CFU/mL; Level 2 = 105–6 CFU/mL; Level 3 = 106–6.5 CFU/mL; Level 4 = 106.5–7 CFU/mL; Level 5 = 107–7.5 CFU/mL; Level 6 = 107.5–8 CFU/mL; and Level 7 = over 108 CFU/mL. For statistical analysis, these categories were regrouped into two levels: low (Levels 1–6) and high (Level 7) based on the median value.
Data analysis
Descriptive statistics of the study variables were calculated according to sex. Distributional differences in categorical variables were described and analysed with the chi-square test, and the mean differences of the continuous variables were analysed with the independent t-test. Questionnaires regarding the parent’s occupation, oral health behaviours, dietary habits and clinical oral health status were categorised into two groups for analysis. Multiple linear regression analyses were used to predict the association of the outcome variables [decayed permanent and deciduous teeth (DT + dt) and gingivitis (PMA index)] with the following independent variables: sex; parents’ occupation (e.g. government worker, professional, or other); tooth brushing frequency (‘more than once daily’ or ‘≤ once daily’); mouth-rinsing habit (‘yes’ or ‘no’); dental visit (‘yes’ or ‘no’); daily consumption of sweet snacks (‘eat’ or ‘don’t eat’); daily consumption of sweet drinks (‘drink’ or ‘don’t drink’); OHI-S score (low score of < 1.5 or high score of ≥ 1.5); and bacteria level [low (Levels 1−6) or high (Level 7)]. All statistical analyses were conducted using SPSS software, version 21.0 (IBM, Tokyo, Japan). The level of significance was P < 0.05.
RESULTS
Sociodemographic and health behaviours
Among the 537 students, 46.7% were boys and 53.3% were girls. Their mean age was 10.6 ± 0.7 years. The most common occupation of the fathers was an unskilled worker (74.3%), and most (59.6%) mothers were dependents/housewives. There were no significant distributional differences in the occupations of fathers and mothers, between boys and girls.
All (100.0%) students brushed their teeth at least once daily, with 36.9% brushing more than once daily. There were no significant distributional differences between boys and girls regarding tooth brushing frequency. Less than a third (28.7%) of students reported a mouth-rinsing habit after meals, with girls rinsing their mouths significantly more than boys (P = 0.004). Most (86.6%) students ate sweet snacks, but there was no significant proportional difference between sexes. The percentage of students who consumed sugary drinks was significantly higher among boys (90.0%) than girls (80.1%; P = 0.001; Table 1). More than half (55.9%) the students had either not visited a dentist within the previous 12 months, or had never visited a dentist. Moreover, the main reason for visiting a dentist was pain associated with the teeth and gums (82.7%). Only 5.5% of the students had visited a dentist for a routine oral examination. There were no significant sex-based differences with regards to history of dental visits or reasons for dental visits (Table 1).
Table 1.
Sociodemographic and oral health behavioural characteristics
| Variables | Total (n = 537) | Boys (n = 251) | Girls (n = 286) | P-value |
|---|---|---|---|---|
| Age (years), mean (SD) | 10.6 (0.7) | 10.7 (0.7) | 10.6 (0.6) | 0.922 |
| Father’s occupation, n (%) | ||||
| Government worker | 44 (8.2) | 17 (6.8) | 27 (9.4) | 0.563 |
| Professional | 34 (6.3) | 18 (7.2) | 16 (5.6) | |
| Unskilled worker | 399 (74.3) | 193 (76.9) | 206 (72.0) | |
| Merchant/seller | 40 (7.4) | 13 (5.2) | 27 (9.4) | |
| Farmer | 12 (2.2) | 6 (2.4) | 6 (2.1) | |
| Dependent/unemployed | 8 (1.5) | 4 (1.6) | 4 (1.4) | |
| Mother’s occupation, n (%) | ||||
| Government worker | 27 (5.0) | 11 (4.4) | 16 (5.6) | 0.309 |
| Professional | 5 (0.9) | 1 (0.4) | 4 (1.4) | |
| Unskilled worker | 178 (33.1) | 91 (36.3) | 87 (30.4) | |
| Merchant/seller | 2 (0.4) | 1 (0.4) | 1 (0.3) | |
| Farmer | 5 (0.9) | 4 (1.6) | 1 (0.3) | |
| Dependent/housewife | 320 (59.6) | 143 (57.0) | 177 (61.9) | |
| Tooth brushing frequency, n (%) | ||||
| Twice or more daily | 198 (36.9) | 84 (33.5) | 114 (39.9) | 0.125 |
| ≤ Once daily | 339 (63.1) | 167 (66.5) | 172 (60.1) | |
| Habit of mouth rinsing, n (%) | ||||
| Yes | 154 (28.7) | 57 (22.7) | 97 (33.9) | 0.004 |
| No | 383 (71.3) | 194 (77.3) | 189 (66.1) | |
| Sweet snacks, n (%) | ||||
| Eat | 465 (86.6) | 224 (89.2) | 241 (84.3) | 0.091 |
| Don’t eat | 72 (13.4) | 27 (10.8) | 45 (15.7) | |
| Sweet drink, n (%) | ||||
| Drink | 455 (84.7) | 226 (90.0) | 229 (80.1) | 0.001 |
| Don’t drink | 82 (15.3) | 25 (10.0) | 57 (19.9) | |
| Dental visit in previous 12 months, n (%) | ||||
| Yes | 237 (44.1) | 110 (43.8) | 127 (44.4) | 0.892 |
| No | 300 (55.9) | 141 (56.2) | 159 (55.6) | |
| Reasons for dental visit, n (%) | (n = 237) | (n = 110) | (n = 127) | |
| Pain or trouble with teeth, gums or mouth | 196 (82.7) | 92 (83.6) | 104 (81.9) | 0.375 |
| Treatment/follow-up treatment | 23 (9.7) | 9 (8.2) | 14 (11.0) | |
| Routine check-up of teeth/treatment | 13 (5.5) | 5 (4.5) | 8 (6.3) | |
| I don’t know/don’t remember | 5 (2.1) | 4 (3.6) | 1 (0.8) | |
P-value numbers marked in bold indicate numbers that are significant.
Oral health status
Table 2 shows the students’ dental caries status and gingival status. The mean number ± standard deviation (SD) of permanent teeth of all students was 21.2 ± 4.6 (20.5 ± 4.7 for boys and 21.7 ± 4.4 for girls). The number of permanent teeth was significantly higher in girls than in boys (P = 0.002). The DMFT was 0.68 ± 1.05 in boys and 0.62 ± 1.00 in girls. The numbers of decayed teeth (DT), missing teeth (MT) and filled teeth (FT) in boys were 0.66 ± 1.04, 0.01 ± 0.09 and 0.01 ± 0.14, respectively, while in girls they were 0.60 ± 0.98, 0.01 ± 0.13 and 0.01 ± 0.10, respectively. No significant sex-based differences were noted in the dental caries experience of the permanent teeth.
Table 2.
Oral health status and oral bacteria level
| Variables | Total (n = 537) | Boys (n = 251) | Girls (n = 286) | P-value |
|---|---|---|---|---|
| Permanent teeth | ||||
| Number of teeth, mean (SD) | 21.2 (4.6) | 20.5 (4.7) | 21.7 (4.4) | 0.002 |
| DT mean (SD) | 0.63 (1.00) | 0.66 (1.04) | 0.60 (0.98) | 0.494 |
| MT mean (SD) | 0.01 (0.11) | 0.01 (0.09) | 0.01 (0.13) | 0.798 |
| FT mean (SD) | 0.01 (0.12) | 0.01 (0.14) | 0.01 (0.10) | 0.890 |
| DMFT mean (SD) | 0.65 (1.02) | 0.68 (1.05) | 0.62 (1.00) | 0.510 |
| Prevalence of dental caries, n (%) | 196 (36.5) | 97 (38.6) | 99 (34.6) | 0.333 |
| Primary teeth | ||||
| Number of teeth, mean (SD) | 3.22 (3.38) | 3.52 (3.59) | 2.96 (3.17) | 0.057 |
| dt mean (SD) | 1.44 (1.93) | 1.50 (1.94) | 1.40 (1.93) | 0.539 |
| ft mean (SD) | 0.01 (0.16) | 0.01 (0.13) | 0.01 (0.18) | 0.851 |
| dft mean (SD) | 1.45 (1.94) | 1.51 (1.95) | 1.41 (1.94) | 0.551 |
| Prevalence of dental caries, n (%) | 278 (51.8) | 139 (55.4) | 139 (48.6) | 0.117 |
| Untreated caries (DT + dt), mean (SD) | 2.07 (2.15) | 2.16 (2.13) | 1.99 (2.18) | 0.384 |
| Prevalence of dental caries in primary and permanent teeth, n (%) | 368 (68.5) | 179 (71.3) | 189 (66.1) | 0.193 |
| PMA index, mean (SD) | 16.2 (5.4) | 17.1 (5.1) | 15.5 (5.6) | < 0.001 |
| Prevalence of gingivitis, n (%) | 531 (98.9) | 248 (98.8) | 283 (99.0) | 0.872 |
| DI-S score, mean (SD) | 1.30 (0.42) | 1.42 (0.42) | 1.19 (0.39) | < 0.001 |
| CI-S score, mean (SD) | 0.14 (0.27) | 0.17 (0.31) | 0.11 (0.23) | 0.014 |
| OHI-S (DI-S + CI-S), mean (SD) | 1.44 (0.59) | 1.59 (0.62) | 1.31 (0.54) | < 0.001 |
| Bacteria level, high (Level 7), n (%) | 287 (53.4) | 156 (62.2) | 131 (45.8) | < 0.001 |
P-value numbers marked in bold indicate numbers that are significant.
CI-S, simplified calculus index; dft, decayed and filled primary teeth; DI-S, simplified debris index; DMFT, decayed, missing and filled permanent teeth; dt, deciduous teeth; DT, decayed permanent teeth; FT, filled teeth; MT, missing teeth; OHI-S, simplified oral hygiene index; PMA, papillary, marginal and attached gingiva; SD, standard deviation.
No significant difference in the mean number of primary teeth was found between boys (3.52 ± 3.59) and girls (2.96 ± 3.17). The mean dft of the primary teeth was 1.51 ± 1.95 in boys and 1.41 ± 1.94 in girls. The mean numbers of decayed deciduous teeth (dt) and filled teeth (ft) were 1.50 ± 1.94 and 0.01 ± 0.13, respectively, in boys; and 1.40 ± 1.93 and 0.01 ± 0.18, respectively, in girls. There were no significant sex-based differences in the dental caries status of primary teeth.
The prevalence of caries in the permanent and primary teeth were 36.5% and 51.8%, respectively. No significant difference in dental caries prevalence was detected between boys and girls.
The mean number of sites with gingival inflammation was significantly higher among boys compared with girls (17.1 ± 5.1 vs. 15.5 ± 5.6; P < 0.001). Boys had significantly higher scores for DI-S (1.42 ± 0.42), CI-S (0.17 ± 0.31) and OHI-S (1.59 ± 0.62) compared with girls [1.19 ± 0.39 (P < 0.001), 0.11 ± 0.23 (P = 0.014) and 1.31 ± 0.54 (P < 0.001), respectively]. The prevalence of gingivitis was 98.8% in boys and 99.0% in girls; however, no sex-based difference was observed. The percentage of boys (62.2%) with high levels of bacteria (Level 7) was significantly higher than in girls (45.8%; P < 0.001).
Out of a total of 537 students, low (Levels 1–6) and high (Level 7) levels of bacteria were observed in 250 and 287 students, respectively (Table 3). Students with high levels of bacteria (Level 7) also had a significantly higher mean number of DI-S (P < 0.001), CI-S (P = 0.016), OHI-S (P < 0.001) and PMA (P < 0.001). No association was found between bacteria levels and mean decayed teeth (DT + dt; P = 0.372).
Table 3.
Association of levels of bacteria with oral health status
| Bacteria level | n (%) | DI-S mean (SD) | CI-S mean (SD) | OHI-S (DI-S + CI-S) mean (SD) | PMA mean (SD) | DT + dt mean (SD) |
|---|---|---|---|---|---|---|
| Low (Levels 1−6) | 250 (46.6) | 1.10 (0.36) | 0.11(0.24) | 1.21 (0.52) | 14.52 (5.96) | 1.98 (1.85) |
| High (Level 7) | 287 (53.4) | 1.48 (0.38) | 0.16 (0.29) | 1.64 (0.57) | 17.71 (4.49) | 2.15 (2.39) |
| P-value | < 0.001 | 0.016 | < 0.001 | < 0.001 | 0.372 |
P-value numbers marked in bold indicate numbers that are significant.
CI-S, simplified calculus index; DI-S, simplified debris index; dt, deciduous teeth; DT, decayed permanent teeth; OHI-S, simplified oral hygiene index; PMA, papillary, marginal and attached gingiva.
Risk indicators of dental caries and gingivitis
Table 4 shows the results of multiple linear regression analyses investigating the relationship between decayed teeth (DT + dt) and gingivitis (PMA), with potential explanatory variables. Significant risk predictors for decayed teeth (DT + dt) included brushing only once daily; no mouth-rinsing habit after meals; dental visits within the last 12 months; daily consumption of sweet snacks; and high OHI-S scores.
Table 4.
Multiple linear regression analysis for the association between dental caries (DT + dt) and gingivitis with their related factors
| Independent variables | Dental caries (DT + dt) |
Gingivitis (PMA) |
||||
|---|---|---|---|---|---|---|
| B | SE | P-value | B | SE | P-value | |
| Sex | 0.119 | 0.186 | 0.522 | −0.057 | 0.963 | 0.890 |
| Father’s occupation | −0.243 | 0.255 | 0.341 | −0.252 | 0.565 | 0.656 |
| Mother’s occupation | 0.694 | 0.381 | 0.069 | 1.943 | 0.843 | 0.022 |
| Tooth brushing frequency | 0.735 | 0.190 | <0. 001 | 1.604 | 0.421 | < 0.001 |
| Daily mouth rinsing habit | 0.647 | 0.203 | 0.001 | 0.713 | 0.449 | 0.113 |
| Dental visit | 0.550 | 0.181 | 0.002 | −0.445 | 0.401 | 0.267 |
| Sweet snacks consumption | 0.656 | 0.268 | 0.015 | −0.122 | 0.593 | 0.837 |
| Sweet drinks consumption | 0.188 | 0.256 | 0.463 | 1.647 | 0.567 | 0.004 |
| OHI–S | 0.531 | 0.168 | < 0.002 | 4.021 | 0.373 | < 0.001 |
| Bacteria level | −0.166 | 0.194 | 0.391 | 0.986 | 0.429 | 0.022 |
P-value numbers marked in bold indicate numbers that are significant.
B = regression coefficient; Sex: boy = 0, girl = 1; Father’s occupation: Others (unskilled workers, farmer, merchant/seller, dependent/unemployed) = 0, Professional or government worker = 1; Mother’s occupation: Others (unskilled workers, farmer, merchant/seller, dependent/unemployed) = 0, Professional or government worker = 1; Tooth brushing frequency: ≥ 2 times daily = 0, once a day = 1; Daily mouth-rinsing habit: Yes = 0, No = 1; Dental visit: No = 0, Yes = 1; Sweet snacks: No = 0, Yes = 1; Sweet drinks: No = 0, Yes = 1; OHI-S: low score (< 1.5) = 0, high score (≥ 1.5) = 1; Bacteria level: low (Levels 1−6) = 0, high (Level 7) = 1.
dt, deciduous teeth; DT, decayed permanent teeth; OHI-S, simplified oral hygiene index; PMA, papillary, marginal and attached gingiva.
Gingivitis scores (based on the PMA index) were significantly associated with the mother’s occupation (government workers or professionals, as opposed to other job types); brushing only once daily; drinking sweet drinks daily; high OHI-S scores; and high levels of bacteria.
DISCUSSION
The present study examined the oral health status and related risk indicators among students who were in the late mixed dentition period. While many studies have reported on the oral health status of preschool children,30, 31 studies targeting students with mixed dentition are very scarce, especially in Myanmar. Therefore, the findings in this study may potentially inform the development of oral health promotion strategies for students in this age group.
The dentition status of Myanmar students was poor overall in that nearly 70% of students had dental caries in the permanent or primary teeth. Compared with the findings of studies conducted in other developing countries, the mean DMFT and dental caries prevalence in the permanent dentition in the present study were lower32, 33, 34; however, the mean dft and prevalence of dental caries in the primary dentition were the same or higher than those of previous reports30, 32, 35.
A previous overview paper36 reported that nearly 60% of 12-year-old Myanmar children had gingival inflammation. In the current study, nearly all students had inflammation in at least one area of the anterior region. The index used in the aforementioned study was different from the indices used in the current study. However, the gingival condition was much poorer in the current study. A possible reason for poor oral health status among students in this study may be the lack of regular dental visits and school oral health promotion programmes. Therefore, they had fewer opportunities to receive adequate oral health education.
Decayed teeth were the greatest contributors to the DMFT scores. Only a few students had filled teeth, and more than half of the students had not visited a dental clinic. These results implied that necessary dental treatments were not regularly provided for the students, and that their parents did not acknowledge the necessity of treatment. The presence of dental caries was significantly associated with dental visits within the preceding year. A previous study37 reported that utilisation of dental services depended on two different types of health behaviours, that is preventive care and illness-related dental visits. In the present study, among students who had visited a dental clinic, 82.7% had done so because of pain or trouble in their teeth or gums. This may be attributed to the lack of oral health awareness by both students and parents. It is necessary to educate them about the importance of dental visits for the prevention of oral disease.
It has been reported across many countries that the oral health-related behaviours and habits of children are strongly influenced by the socioeconomic status of their parents.38, 39 The parents’ (especially the mothers’) level of education or knowledge has a great impact on the child’s oral health.5, 40 In this study, students whose mothers were government workers or professionals were more likely to have gingivitis. In Myanmar, people who work as government workers and professionals are regarded as having a higher socioeconomic status compared with individuals in other occupations. Therefore, it seems plausible that parents of a higher socioeconomic status are more able to afford sugary snacks and drinks for their children. Furthermore, mothers who work as civil servants or professionals spend substantial time away from their home; therefore, they may not have sufficient time to oversee their children, compared with mothers working in other occupations.
In Myanmar, every school has a canteen, and such facilities potentially serve as a readily available source of cariogenic foods and beverages. This study showed that the consumption of highly cariogenic foods, especially sweet snacks, was significantly associated with dental caries, a finding that has been firmly established in previous studies6, 41. This study also found that the consumption of sweet drinks was a risk indicator for gingivitis. This supports previous studies42, 43 that have reported that ingredients in sugary soft drinks enhance inflammation, and contribute to a higher risk of periodontal disease.
In the present study, brushing teeth only once a day was a significant risk indicator for dental caries and gingivitis. Moreover, the lack of mouth rinsing after a meal was also associated with dental caries. These results corroborated the findings of other studies6, 44. The modality of tooth brushing is an important determinant of dental caries and gingivitis. All students in this study brushed their teeth at least once daily, yet their oral health status was not necessarily good. At home, students should be taught to choose less cariogenic food, and should be guided to practice an adequate oral hygiene regimen to prevent dental caries and gingivitis. It has been widely established that the early implementation of mechanical plaque control methods such as tooth brushing and flossing is adequate to prevent plaque-induced gingivitis and dental caries in children10, 45, 46.
In the present study, the OHI-S index was found to be a risk indicator for both dental caries and gingivitis, supporting the results of previous studies conducted in other countries47, 48. This was not surprising, given that OHI-S is a direct measure of dental plaque, which is the prime aetiological agent of both caries and periodontal disease. This study found significant associations between levels of bacteria (as determined by DEPIM) and both oral hygiene and gingivitis, even after adjusting for other confounding variables in multiple linear regression analyses. This suggests that the bacterial counter machine could potentially be used to evaluate oral hygiene status, and serve as a tool to motivate students to clean their teeth. However, the study revealed that total bacteria levels in the dental plaque samples were not associated with dental caries. This may be explained by the specific plaque hypothesis, whereby only a few specific species, such as Streptococcus mutans and Streptococcus sobrinus, are actively involved in dental caries49. While the bacteria counter machine can quantitatively detect biological cells according to their variability, it cannot specifically detect cariogenic bacteria. Moreover, because this was a cross-sectional study, additional longitudinal studies are required to check the relationship.
No sex-based difference in caries experience was observed in this study, although girls had a significantly higher number of permanent teeth. Prior studies have reported that boys have a higher dental caries experience than girls33, 50. Although the OHI-S score, gingivitis (PMA index), and the number of bacteria in dental plaque were significantly lower in girls by bivariate analysis, sex was not associated with dental caries or gingivitis in multiple linear regression analyses after adjusting for other independent variables. In the current study, boys tended to consume more sugary drinks, and experienced more gingivitis compared with girls. A similar finding has also been reported in a previous study42. Among the investigated oral hygiene behaviours, the only significant difference was mouth-rinsing habit, which was significantly higher in girls. These results suggest that poor oral hygiene, oral hygiene habits and dietary behaviours were the major determinants of dental caries and gingivitis, rather than sex per se.
Children who have dental caries in the primary dentition are more likely to develop dental caries in the permanent dentition51. Thus, during the mixed dentition period, appropriate measures should be taken to promote the oral health of Myanmar students. The risk indicators of dental caries and gingivitis determined in this study may make it possible to identify students at a higher risk for oral disease, and allow for the earlier implementation of preventive measures. Moreover, the students can easily recognise their oral hygiene status by checking the face icon in the bacteria counter machine, which can be used as one of the motivating materials for the improvement of oral health.
A limitation in the present study was the representativeness of the sample. A random sampling method was employed, but the sample was chosen only from one area in Myanmar. Therefore, the results of this study may have limited generalisability to other regions in the country. As the data pertaining to oral health behaviours and habits were obtained using a self-report survey, there was a possibility of information and response bias. Another limitation in this study came from using some questions with categorical responses to record dietary sugar intake. Furthermore, this was a cross-sectional study; therefore, a longitudinal study needs to be implemented to confirm the current findings.
CONCLUSION
Myanmar students with a mixed dentition had a high prevalence of dental caries and gingivitis, as well as poor oral hygiene, and inadequate oral healthcare habits. The socioeconomic condition, oral hygiene status and oral health habits were risk indicators for dental caries and gingivitis. Cooperative efforts by school authorities, teachers, health professionals and parents in school oral health promotion programmes would be essential for the improvement of oral health status of Myanmar students.
Acknowledgements
The authors wish to express their appreciation to all school children who participated in the study.
Conflict of interest
All authors declare no potential conflicts of interest in this study.
Funding information
This study was supported by a dental hygiene research grant 2018 from the FUTOKU Foundation (Tokyo, Japan), and the Tokyo Medical and Dental University (Tokyo, Japan).
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