Abstract
Objectives: The aim of this study was to investigate the oral health of Nepalese schoolchildren relative to their sociodemographic characteristics. Methods: This school-based, cross-sectional study was conducted among 5–6-, 12- and 15-year-old Nepalese children in 18 randomly selected districts of the 75 in Nepal. Clinical parameters were recorded according to the World Health Organization (WHO) guidelines. Results were presented as mean (SD) and proportions; the chi-square test, t-test and one way-ANOVA were also performed. The risk of dental caries in association with the place of residence was presented according to the outcome of a binary logistic regression analysis. Results: The mean d-value for the 5–6-year-old children was 5.0 (4.22), which was higher than the mean D-values for the 12- and 15-year-old subjects, of 1.3 (1.77) and 1.9 (2.28), respectively. The youngest children, as well as children from the Kathmandu Valley, were likely to have more untreated caries lesions than children in the other age groups. The mean number of teeth with severe consequences of dental caries (pulpitis/ulceration/fistula/abscess or pufa/PUFA) was 1.3 (1.91) for the 5–6-year-old children, 0.1 (0.35) for the 12-year-old children and 0.3 (0.75) for the 15-year-old children. All age groups had gingival bleeding on probing in more than 15% of teeth. Children from rural locations had significantly more gingival bleeding than urban children. The same was true for 15-year-old girls compared with boys of the same age. Conclusions: Among Nepalese children, oral diseases are common, and geographical variation is prevalent. The health policy should address the alarming oral health situation and need for urgent treatment and population-based preventive programmes that is evident in Nepal.
Key words: Dental caries, geo-maps, gingival bleeding, oral health, Nepal
Introduction
The global burden of oral diseases has increased in the past two decades, with dental caries being the most prevalent1. Dental caries and periodontal diseases affect a majority of children globally2. Oral diseases, mainly caries and periodontitis, account for approximately 15 million years of life lost annually1. The impact of periodontal diseases on general health is well established3. Of concern, untreated caries may also cause pain, discomfort and even severe general infections4. Despite being preventable and treatable, these diseases often remain untreated, particularly in developing countries5. There is lack of knowledge on the aetiology of the diseases. Poor access to oral health care, especially in remote areas of developing countries, may result in failure to treat oral diseases, while in developed countries, oral health care is mostly included in primary health care (PHC) services6.
Nepal is a landlocked, multi-ethnic country which is divided into three ecological and five administrative developmental regions and 75 districts. The first National Oral Health Pathfinder Survey conducted in Nepal in 2004 among World Health Organization (WHO) index age groups revealed that the prevalence of dental caries is low, except among 5–6-year-old children, but the prevalence of gingivitis is high among all children7. According to the WHO recommendation, clinical oral health surveys should be conducted every 5–6 years to gather information on the oral health situation and services needed8. Consequently, a national oral health survey incorporating all these aspects was considered necessary because of recent changes in the Nepalese society9.
The aim of this study was to investigate the oral health of Nepalese schoolchildren relative to their sociodemographic characteristics. We hypothesised that there is residence-related variation in the prevalence of dental caries but not in the prevalence of gingivitis.
Methods
This study was a school-based, cross-sectional clinical study conducted among schoolchildren, representing WHO index age groups (5–6, 12 and 15 years of age), from 27 schools in 18 out of 75 districts in Nepal (Figure 1).
Figure 1.
Geo-maps showing the untreated caries experience among Nepalese schoolchildren.
Sample sites
Stratified random sampling was used considering the ecological regions (Tarai in the south, Mountain in the north and Hill in between) and the administrative developmental regions (Eastern, Central, Western, Mid-Western and Far-Western). Three districts from each five developmental region were selected to represent simultaneously each ecological region. In the Kathmandu Valley, the most densely populated urban area in Nepal, all three districts were included (Figure 1). The sample sites were considered as location with access to oral health care (or urban)/Location with no access to oral health care (or rural), based on access to a health-care clinic (government-operated or private) with a dental office and staff facilities within 10 km from the sample site. The decision was made after consulting a district health officer or primary health centre. Ethnicity among the study population was classified into seven groups, as suggested by the Nepal Demography and Health Survey (2006)10. After obtaining the list of schools from the Ministry of Education, the sample sites were selected using convenience sampling (one to two schools per district).
Study population
To estimate the sample size, a power calculation was carried out using the G*power software (GPOWER version 3.1; Samsovej 21, Hinnerup, Denmark) with 95% power and the Mann–Whitney U-test to analyse differences between means [e.g. difference in the number of decayed primary (d) and decayed permanent (D) teeth: d/D = 0.3] with alpha-type error at 0.05. The sample size of n = 340 in each age group was considered sufficient.
Lists of students in all age groups were requested from the participant schools before the study. All 5–6-year-old children, accompanied by their parents as requested, were included without randomising. A maximum of 60 children in the two oldest age groups could be examined each day, and randomisation was carried out as follows. First, the children were asked to form two lines (according to their age) in the school assembly ground. If, for instance, 120 children were present, every second child was selected to participate (sample fraction). One school refused to participate. Accordingly 1,137 out of 1,151 schoolchildren gave their permission and participated in both the survey and the clinical examination. The participation rates in each developmental region were as follows: 96.68% for the Eastern region; 99.64% for the Central region; 97.80% for the Western region; and 100% for both Mid-Western and Far-Western regions.
The age (birth year) and date of birth of each child were obtained from the school authorities and recorded in the individual data-collection sheet before the study.
Clinical examination
The clinical examination was conducted according to the WHO guidelines and criteria8. The protocol was confirmed during the training sessions. Clinical examinations were performed in the school premises using external [light-emitting diode (LED)] headlights, intra-oral mirrors and WHO Community Periodontal probes. The examiners wore a uniform, a disposable mask and gloves. The participant lay down on a bench and the examiner was seated behind them.
Cariological status
The cariological status was evaluated at the tooth level by visual-tactile examination, investigating the depth and estimating activity (as well as the texture) of tooth surfaces using the WHO probe. Teeth were not cleaned professionally or air-dried before the examination. Each tooth was scored as sound, decayed, filled with or without caries, missing because of caries or fissure sealed. Teeth with even one surface affected were considered as carious or filled. Missing because of caries was confirmed by asking the participant/parent the cause.
pufa/PUFA
The recently developed pufa/PUFA index measures the consequences of untreated dental caries11. The index measures the following: visible pulp or pulp involvement (p/P), and/or ulceration of the oral mucosa as a result of root fragments (u/U), and/or a fistula (f/F), and/or an abscess (a/A). The pufa/PUFA index was assessed as advised originally11 and the lowercase letters were used for primary dentition and uppercase letters for permanent dentition. Only one score was assigned per tooth. In addition to mean (SD) pufa/PUFA scores, pufa/PUFA sum scores were calculated as the total number of teeth with any pufa/PUFA criterion.
Gingival status
The gingiva of all teeth present was examined at six sites (distobuccal, midbuccal, mesiobuccal, distolingual, midlingual and mesiolingual). The tip of the probe was gently inserted between the gingiva and the tooth, following the anatomical configuration. A per-tooth score was registered based on the absence or presence of bleeding at any of the sites.
Dental trauma
If any signs of treated/untreated trauma were present, the tooth was recorded as traumatised as follows: enamel fracture only; enamel and dentine fracture; pulp involvement; tooth missing as a result of trauma; treated trauma.
Fluorosis
The modified Dean’s fluorosis index was used to record enamel fluorosis12. This index categorises fluorosis as follows: normal; questionable; very mild; mild; moderate; or severe.
Treatment urgency
According to clinical findings, individuals were provided with one of the following scores: no oral treatment need; preventive treatment needed (no caries, mild gingivitis); prompt treatment needed (caries, gingivitis); or immediate treatment needed.
Quality control and quality assurance
Three registered Nepali dentists were trained and calibrated to conduct the clinical examinations. All findings were recorded manually on data-collection sheets, based on the WHO model8, by two trained enumerators. Two senior researchers with experience of similar oral health surveys and validation processes conducted the training and calibration sessions.
Training provided in April 2016 covered both theoretical and practical requirements. All trainees were provided with the WHO manual8. A lecture provided detailed information, with illustrations, on the clinical parameters to be investigated. During the calibration, 20 extracted teeth with a variety of carious lesions were examined. A consensus was reached by the examiners and trainees about the score. The examiners were trained to use 20 g of gingival probing force with the help of a letter scale (Electronic Letter Scale, Art. no 34-9710, Helsinki, Finland).
After the theory session, each trainee, under the supervision of the trainers, examined five children from each age group and the enumerators practised recording the findings. To ensure a high quality of the clinical examination, the training session was repeated briefly before the field stage and again 1 week later. Because the field stage lasted only 11 weeks, further training or calibration was not considered necessary. Intra-examiner agreement was calculated using extracted teeth and it ranged from 0.84 to 0.97. A total of five children were examined by the three examiners, while the trainers acted as the gold standard. The inter-examiner kappa value for d/D was 0.87, for pufa/PUFA was 0.63, for dental trauma was 1.00 and for fluorosis was 0.53.
Fluoride in drinking water
To assess the concentration of fluoride in school drinking water, water samples (500 ml) were collected in commercially available clean and dry bottles. The fluoride concentration (ppm) was assessed using the SPANDS fluoride reagent solution (Hach Company, Loveland, CO, United States).
Ethical clearance
The study protocol and material were approved by the Ethics Committee, School of Medical Sciences, Kathmandu University (IRC No. 60/15, KUSMS) and permission for the study was obtained from the Northern Ostrobothnia Hospital District (18/2016). The Ethics Committee also approved the consent procedure. The entire study was conducted in full accordance with the World Medical Association Declaration of Helsinki. The Ministry of Health and the Ministry of Education, Government of Nepal, gave their written permission for the study, and the district health and education authorities also gave their permission. The schools were contacted via an informative letter describing the study. Written consent was required from the school headteacher before starting the field phase. A letter was also sent to the schools requesting the participation of the older children and parents of the youngest ones. Parents of the youngest children gave written consent, while verbal consent was obtained and recorded from the older children. Participation was voluntary and the clinical examination caused no physical harm or pain to the participants.
Statistical analysis
The data recorded manually on data sheets were transferred to the SPSS software (IBM SPSS Statistics for Windows, version 24.0. Armonk, NY: IBM Corp.) for analyses.
Demographic information about the study population was presented for age group, gender (male/female), location with access to oral health care (urban/rural), ecological region, developmental region, ethnicity and district. The mean (SD) values of d/D, dmf/DMF (for which d/D > 0 indicates a present caries treatment need and dmf/DMF > 0 indicates a present caries treatment need and past caries experience), pufa/PUFA, bleeding on probing (BOP) (number of teeth with gingival bleeding) were calculated. Proportions of children with d/D/dmf/DMF > 0, pufa/PUFA > 0, dental traumas > 0, fluorosis > 0 and BOP > 15% and with different treatment needs were calculated.
The t-test and one-way ANOVA were used to compare the means between the groups. To compare the proportions between groups, the chi-square test was performed. To assess the effect of geographical variation on dental caries prevalence, a binary logistic regression model was carried out [odds ratio (OR) and 95% confidence interval (CI)], having untreated carious lesions (d/D) as the dependent variable and gender and place of residence as the independent variables – the Kathmandu Valley was used as the reference and the OR estimates were illustrated using geo-mapping. The statistical significance level was set at P < 0.05.
Geographical Information System
To visualise the results in the present study, the examination sites were geo-referenced and imported to ArcGIS, version 10.5 (Environmental Systems Research Institute, Inc., Redlands, CA, USA) to create geo-maps.
Results
Altogether, 1,137 children were examined clinically. The children were distributed quite evenly in the study group according to age and gender (Table 1). The proportion of those requiring restorative treatment (d/D > 0) was 78.8% among the 5–6 years age group, 53.4% among the 12 years age group and 60.8% among the 15 years age group. The proportions of those with d/D > 0 and dmf/DMF>0 were almost identical (Table 2).
Table 1.
Demographic information on the study population
| Characteristic | Participants (%) | Total % (n) | ||
|---|---|---|---|---|
| 5–6 years of age (n = 340) | 12 years of age (n = 414) | 15 years of age (n = 383) | ||
| Gender | ||||
| Boys | 51.8 | 51.4 | 54.3 | 52.5 (597) |
| Girls | 48.2 | 48.6 | 45.7 | 47.5 (540) |
| Developmental region | ||||
| Eastern | 15.9 | 21.7 | 23.2 | 20.5 (233) |
| Central | 23.8 | 22.2 | 28.7 | 24.9 (283) |
| Western | 19.4 | 20.3 | 19.1 | 19.6 (223) |
| Mid-western | 17.4 | 15.0 | 9.1 | 13.7 (156) |
| Far-western | 23.5 | 20.8 | 19.8 | 21.3 (242) |
| Ecological region | ||||
| Mountain | 31.8 | 32.6 | 30.5 | 31.7 (360) |
| Hill | 50.6 | 47.3 | 47.3 | 48.3 (549) |
| Tarai | 17.6 | 20.0 | 22.2 | 20.1 (228) |
| Location | ||||
| With access to oral health care (Urban) | 50.9 | 51.7 | 57.2 | 53.3 (606) |
| With no access to oral health care (Rural) | 49.1 | 48.3 | 42.8 | 46.7 (531) |
| Ethnic group | ||||
| Brahaman/Chhetri | 51.8 | 49.0 | 45.7 | 48.7 (554) |
| Tarai Madhesi | 3.2 | 4.3 | 7.0 | 4.9 (56) |
| Dalits | 10.3 | 9.7 | 7.8 | 9.2 (105) |
| Newar | 5.0 | 4.8 | 9.1 | 6.3 (72) |
| Janajati | 27.6 | 29.5 | 28.7 | 28.7 (326) |
| Muslim | 2.1 | 2.7 | 1.6 | 2.1 (24) |
Table 2.
Dental caries experience, untreated dental caries and pulp involvement, ulceration, fistula or abscess (pufa/PUFA) experience in relation to age group, gender, location, developmental region, ecological region and ethnicity
| Age group | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Variables | 5–6 years | 12 years | 15 years | ||||||
| dmf>0 Mean (SD) | d>0 Mean (SD) | pufa>0 Mean (SD) | DMF>0 Mean (SD) | D>0 Mean (SD) | PUFA>0 Mean (SD) | DMF>0 Mean (SD) | D>0 Mean (SD) | PUFA>0 Mean (SD) | |
| Gender | *,† | ||||||||
| Boys | 5.22 (4.14) | 5.16 (4.10) | 1.29 (1.74) | 1.28 (1.87) | 1.24 (1.82) | 0.09 (0.32) | 1.88 (2.20) | 1.77 (2.16) | 0.23 (0.68) |
| Girls | 4.71 (4.40) | 4.66 (4.35) | 1.28 (2.08) | 1.47 (1.72) | 1.44 (1.70) | 0.11 (0.38) | 2.11 (2.53) | 2.00 (2.41) | 0.33 (0.82) |
| Location | |||||||||
| Urban | 5.06 (4.52) | 4.98 (4.45) | 1.24 (1.98) | 1.29 (1.74) | 1.26 (1.71) | 0.11 (0.35) | 1.85 (2.19) | 1.74 (2.14) | 0.28 (0.78) |
| Rural | 4.88 (4.01) | 4.86 (3.98) | 1.33 (1.84) | 1.45 (1.87) | 1.42 (1.82) | 0.10 (0.35) | 2.18 (2.56) | 2.05 (2.45) | 0.27 (0.71) |
| Developmental region | **,‡ | **,‡ | *,‡ | ||||||
| Eastern | 5.47 (3.81) | 5.39 (3.70) | 1.48 (2.09) | 1.33 (1.76) | 1.30 (1.72) | 0.11 (0.34) | 2.24 (2.97) | 2.18 (2.95) | 0.34 (0.85) |
| Central | 4.02 (3.95) | 3.94 (3.89) | 0.78 (1.27) | 1.81 (2.02) | 1.78 (2.00) | 0.12 (0.42) | 1.99 (2.08) | 1.86 (2.02) | 0.14 (0.44) |
| Western | 7.13 (5.00) | 7.07 (4.96) | 1.92 (2.38) | 1.40 (1.96) | 1.33 (1.93) | 0.15 (0.42) | 1.95 (2.14) | 1.70 (1.78) | 0.28 (0.68) |
| Mid-western | 4.45 (3.84) | 4.45 (3.84) | 1.07 (1.65) | 1.12 (1.51) | 1.12 (1.51) | 0.05 (0.22) | 1.43 (2.16) | 1.32 (2.07) | 0.40 (1.04) |
| Far-western | 4.20 (3.95) | 4.18 (3.90) | 1.23 (1.91) | 1.10 (1.55) | 1.06 (1.49) | 0.05 (0.22) | 1.98 (2.24) | 1.95 (2.24) | 0.31 (0.82) |
| Ecological region | **,‡ | **,‡ | *,‡ | *,‡ | |||||
| Mountain | 5.60 (4.40) | 5.55 (4.38) | 1.55 (1.91) | 1.78 (2.00) | 1.73 (1.95) | 0.15 (0.45) | 2.48 (2.73) | 2.29 (2.59) | 0.37 (0.83) |
| Hill | 4.80 (4.13) | 4.73 (4.04) | 1.13 (1.87) | 1.34 (1.75) | 1.32 (1.73) | 0.08 (0.29) | 1.94 (2.18) | 1.83 (2.14) | 0.21 (0.65) |
| Tarai | 4.34 (4.37) | 4.34 (4.37) | 1.27 (1.99) | 0.76 (1.34) | 0.75 (1.34) | 0.08 (0.27) | 1.39 (2.04) | 1.38 (2.00) | 0.25 (0.77) |
| Ethnic group | *,‡ | *,‡ | *,‡ | ||||||
| Brahaman/ Chhetri | 4.98 (4.06) | 4.92 (3.98) | 1.28 (1.90) | 1.22 (1.60) | 1.21 (1.59) | 0.06 (0.26) | 1.94 (2.26) | 1.86 (2.23) | 0.29 (0.72) |
| Tarai madhesi | 3.28 (2.97) | 3.28 (2.97) | 0.82 (1.48) | 0.67 (1.24) | 0.56 (0.99) | 0.06 (0.24) | 1.71 (2.19) | 1.63 (2.08) | 0.08 (0.27) |
| Dalits | 4.75 (4.39) | 4.72 (4.35) | 1.28 (2.01) | 1.00 (1.64) | 0.93 (1.48) | 0.10 (0.45) | 1.74 (2.07) | 1.74 (2.07) | 0.26 (0.86) |
| Newar | 5.53 (4.75) | 5.53 (4.75) | 1.18 (1.88) | 1.80 (1.91) | 1.80 (1.91) | 0.30 (0.66) | 2.20 (2.23) | 2.15 (2.24) | 0.29 (0.67) |
| Janajati | 5.30 (4.71) | 5.25 (4.68) | 1.41 (2.00) | 1.78 (2.12) | 1.73 (2.10) | 0.14 (0.37) | 2.22 (2.68) | 2.00 (2.50) | 0.30 (0.85) |
| Muslim | 2.72 (2.93) | 2.72 (2.93) | 0.58 (1.14) | 1.28 (1.74) | 1.28 (1.74) | 0.10 (0.31) | 0.17 (0.41) | 0.17 (0.41) | 0.00 (0.00) |
Values are given as mean [standard deviation (SD)].dmf/DMF, decayed, missing or filled primary (lowercase) or permanent (uppercase) tooth, d/D; decayed primary (lowercase) or permanent (uppercase) tooth, pufa/PUFA, pulp involvement, ulceration, fistula or abscess in primary (lowercase) or permanent (uppercase) teeth.
t-test.
One-way ANOVA.
P < 0.05.
P < 0.001.
Among the 5- to 6-year-old children, the prevalence of dental caries was significantly higher among participants from the Western region than among participants from the other regions (Table 2). Among them, a higher risk for restorative treatment need (d) per se was discovered in remote districts (Banke, Mugu, Mustang, Okhaldhunga, Palpa and Surkhet) compared with the Kathmandu Valley (Figure 1). On the other hand, living outside the Kathmandu Valley was a protective factor among children in the 12- and 15-year age-groups. Regarding ecological region, the need for restorative treatment was lowest in Tarai and highest in the Mountain region, among all age groups (Table 2, Figure 1).
The prevalence of pufa/PUFA>0 was highest (47.1%) among 5–6-year-old children, while the respective figures were 19.6% for the 12-year-old children and 16.7% for the 15-year-old children. The most common sequela of untreated dental caries was pulpitis, and abscess and fistula were, respectively, the second and third most common sequelae; the difference between the prevalence of the components was statistically significant (P < 0.001) between the 5–6-year-old children and the 15-year-old children (Table 3). [Corrections added on 20 June 2018 after initial online publication: The percentage values in the first sentence have been amended.]
Table 3.
Prevalence (%) of different components of the pulp involvement, ulceration, fistula or abscess (pufa/PUFA) index in primary (lowercase) or permanent (uppercase) teeth, in relation to age group, gender, location, developmental region, ecological region and ethnicity
| Age group | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Variable | 5–6 years | 12 years | 15 years | |||||||||
| p | u | f | a | P | U | F | A | P | U | F | A | |
| Gender | ||||||||||||
| Boys | 43.2 | 0.0 | 10.8 | 10.8 | 7.0 | 0.0 | 0.5 | 0.5 | 13.0 | 0.0 | 0.5 | 1.4 |
| Girls | 38.4 | 0.6 | 7.9 | 9.1 | 8.0 | 0.0 | 0.0 | 1.5 | 17.1 | 0.6 | 1.1 | 2.3 |
| Location | ||||||||||||
| Urban | 39.9 | 0.0 | 8.70 | 19.2 | 7.9 | 0.0 | 0.0 | 0.9 | 14.6 | 0.5 | 0.5 | 2.3 |
| Rural | 40.9 | 0.6 | 10.2 | 10.8 | 7.0 | 0.0 | 0.5 | 1.0 | 15.2 | 0.0 | 1.2 | 1.2 |
| Developmental region | ||||||||||||
| Eastern | 48.1 | 1.9 | 5.6 | 13.0 | 8.9 | 0.0 | 0.0 | 2.2 | 18.0 | 0.0 | 1.1 | 3.4 |
| Central | 32.1 | 0.0 | 6.2 | 2.5 | 6.5 | 0.0 | 0.0 | 2.2 | 8.2 | 0.0 | 0.9 | 1.8 |
| Western | 54.5 | 0.0 | 12.1 | 18.2 | 13.1 | 0.0 | 0.0 | 0.0 | 19.2 | 0.0 | 0.0 | 1.4 |
| Mid-western | 33.9 | 0.0 | 13.6 | 10.2 | 4.8 | 0.0 | 0.0 | 0.0 | 14.3 | 0.0 | 2.9 | 0.0 |
| Far-western | 38.8 | 0.0 | 10.0 | 8.8 | 3.5 | 0.0 | 1.2 | 0.0 | 17.1 | 0.0 | 0.0 | 1.3 |
| Ecological region | ||||||||||||
| Mountain | 45.4 | 0.9 | 10.2 | 11.1 | 8.9 | 0.0 | 0.7 | 1.5 | 21.4 | 0.0 | 0.9 | 1.7 |
| Hill | 40.7 | 0.0 | 8.7 | 6.4 | 7.1 | 0.0 | 0.0 | 0.5 | 11.6 | 0.0 | 1.1 | 1.7 |
| Tarai | 33.3 | 0.0 | 10.0 | 18.3 | 6.0 | 0.0 | 0.0 | 1.2 | 12.9 | 1.2 | 0.0 | 2.4 |
| Ethnic group | ||||||||||||
| Brahaman/Chhetri | 42.6 | 0.0 | 11.9 | 9.1 | 4.4 | 0.0 | 0.5 | 1.0 | 17.1 | 0.6 | 0.0 | 1.7 |
| Tarai madhesi | 27.3 | 0.0 | 0.0 | 9.1 | 0.0 | 0.0 | 0.0 | 5.6 | 7.4 | 0.0 | 0.0 | 0.0 |
| Dalits | 31.4 | 0.0 | 5.7 | 11.4 | 5.0 | 0.0 | 0.0 | 0.0 | 10.0 | 0.0 | 0.0 | 3.3 |
| Newar | 35.3 | 0.0 | 11.8 | 0.0 | 20.0 | 0.0 | 0.0 | 0.0 | 14.3 | 0.0 | 2.9 | 5.7 |
| Janajati | 44.7 | 1.1 | 7.4 | 12.8 | 12.3 | 0.0 | 0.0 | 0.8 | 15.5 | 0.0 | 1.8 | 0.9 |
| Muslim | 28.6 | 0.0 | 0.0 | 14.3 | 9.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
a/A, abscess; f/F, fistula; p/P, pulp involvement; u/U, ulceration of the oral mucosa as a result of root fragments.
From the youngest to the oldest age groups, the mean number of teeth with BOP was 13.1 (4.87), 14.8 (6.52) and 19.0 (6.58). The proportion of those with BOP>15% was more than 90% in all age groups. Additionally, children’s location with no access to oral health care (rural) had significantly higher BOP than the others (Table 4). The prevalence of dental trauma was 1.8% for 5–6-year-old children, 5.1% for 12-year-old children and 6.3% for 15-year-old children. The prevalence was similar throughout the country (Table 4).
Table 4.
Number of teeth with gingival bleeding and prevalence of bleeding on probing (BOP), dental trauma and fluorosis in relation to age group, gender, location, developmental region, ecological region and ethnicity
| Variables | 5-6-year-olds | 12-year-olds | 15-year-olds | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gingival bleedingmean (SD) | Bleeding on probing | Dental trauma (%) | Fluorosis (%) | Gingival bleedingmean (SD) | Bleeding on probing | Dental trauma (%) | Fluorosis (%) | Gingival bleedingmean (SD) | Bleeding on probing | Dental trauma (%) | Fluorosis (%) | ||||
| BOP ≤ 15% | BOP > 15% | BOP ≤ 15% | BOP > 15% | BOP ≤ 15% | BOP > 15% | ||||||||||
| Gender | |||||||||||||||
| Boys | 13.22 (4.85) | 4.0 | 96.0 | 1.7 | 4.5 | 13.72 (6.55) | 7.0 | 93.0 | 7.0 | 12.7 | 18.80 (6.40) | 1.9 | 98.1 | 7.2 | 13.0 |
| Girls | 12.88 (4.90) | 6.7 | 93.3 | 1.8 | 3.7 | 15.83 (6.33) | 3.5 | 96.5 | 3.0 | 10.9 | 19.13 (6.78) | 2.3 | 97.7 | 5.1 | 12.6 |
| Location | ***,‡ | **,† | ***,‡ | **,† | **,† | *,‡ | **,† | ||||||||
| Urban | 12.01 (4.84) | 6.9 | 93.1 | 2.3 | 7.5 | 13.59 (6.92) | 8.9 | 91.1 | 7.0 | 16.4 | 18.32 (6.72) | 2.7 | 97.3 | 5.9 | 17.4 |
| Rural | 14.14 (4.67) | 3.6 | 96.4 | 1.2 | 0.6 | 15.98 (5.82) | 1.5 | 98.5 | 3.0 | 7.0 | 19.79 (6.29) | 1.2 | 98.8 | 6.7 | 6.7 |
| Developmental region | ***,§ | ***,† | **,† | ***,§ | ***,† | *,† | ***,§ | *,† | |||||||
| Eastern | 11.15 (3.49) | 3.7 | 96.3 | 0.0 | 5.6 | 13.60 (6.56) | 8.9 | 91.1 | 2.2 | 15.6 | 17.31 (6.92) | 4.5 | 95.5 | 6.7 | 16.9 |
| Central | 14.64 (4.08) | 0.0 | 100.0 | 1.2 | 4.9 | 16.92 (5.64) | 1.1 | 98.9 | 7.6 | 13.0 | 21.15 (5.99) | 0.9 | 99.1 | 7.3 | 7.3 |
| Western | 10.55 (6.25) | 19.7 | 80.3 | 4.5 | 4.5 | 12.38 (7.48) | 14.3 | 85.7 | 8.3 | 14.3 | 17.05 6.86) | 2.7 | 97.3 | 4.1 | 17.8 |
| Mid-western | 15.05 (4.45) | 1.7 | 98.3 | 0.0 | 5.1 | 15.40 (5.93) | 1.6 | 98.4 | 1.6 | 9.7 | 18.89 (6.65) | 2.9 | 97.1 | 0.0 | 5.7 |
| Far-western | 13.34 (4.09) | 2.5 | 97.5 | 2.5 | 1.3 | 15.44 (5.88) | 0.0 | 100.0 | 4.7 | 5.8 | 19.53 (5.68) | 0.0 | 100.0 | 9.2 | 14.5 |
| Ecological region | ***,§ | *,† | ***,† | ***,§ | ***,† | *,† | ***,† | ||||||||
| Mountain | 15.44 (4.07) | 0.9 | 99.1 | 0.0 | 0.0 | 16.81 (5.85) | 1.5 | 98.5 | 2.2 | 8.9 | 20.16 (6.37) | 0.0 | 100.0 | 5.1 | 8.5 |
| Hill | 12.29 (4.80) | 6.4 | 93.6 | 2.3 | 3.5 | 14.18 (6.64) | 7.1 | 92.9 | 5.6 | 7.7 | 18.31 (6.88) | 4.4 | 95.6 | 7.2 | 7.2 |
| Tarai | 10.95 (4.78) | 10.0 | 90.0 | 3.3 | 13.3 | 12.71 (6.42) | 7.2 | 92.8 | 8.4 | 26.5 | 18.64 (5.97) | 0.0 | 100.0 | 5.9 | 30.6 |
| Ethnic group | ***,† | **,§ | *,† | ***,† | |||||||||||
| Brahaman/ Chhetri | 13.54 (4.55) | 4.5 | 95.5 | 1.1 | 1.1 | 13.56 (6.13) | 5.9 | 94.1 | 8.4 | 11.8 | 18.70 (6.45) | 2.3 | 97.7 | 7.4 | 8.6 |
| Tarai madhesi | 15.36 (3.78) | 0.0 | 100.0 | 0.0 | 27.3 | 16.33 (5.99) | 0.0 | 100.0 | 0.0 | 27.8 | 22.04 (5.56) | 0.0 | 100.0 | 7.4 | 33.3 |
| Dalits | 13.03 (5.38) | 5.7 | 94.3 | 2.9 | 5.7 | 17.48 (5.93) | 2.5 | 97.5 | 2.5 | 5.0 | 17.23 (6.12) | 0.0 | 100.0 | 10.0 | 43.3 |
| Newar | 12.65 (5.07) | 5.9 | 94.1 | 0.0 | 0.0 | 14.00 (8.71) | 20.0 | 80.0 | 5.0 | 5.0 | 18.83 (7.59) | 8.6 | 91.4 | 2.9 | 11.4 |
| Janajati | 12.22 (5.29) | 7.4 | 92.6 | 3.2 | 4.3 | 15.78 (6.55) | 4.1 | 95.9 | 1.6 | 12.3 | 19.24 (6.67) | 0.9 | 99.1 | 4.5 | 5.5 |
| Muslim | 9.57 (1.90) | 0.0 | 100.0 | 0.0 | 42.9 | 13.55 (7.41) | 0.0 | 100.0 | 0.0 | 18.2 | 16.50 (5.54) | 0.0 | 100.0 | 0.0 | 33.3 |
SD, standard deviation.
χ-test.
t-test.
One-way ANOVA.
P < 0.05.
P < 0.01.
P < 0.001.
In most districts, the fluoride level was low, exceeding 0.8 ppm only in one district (Parsa), and only 4% of the study population was exposed to the optimal level of fluoride in drinking water (Table 5). A high fluoride concentration was associated with reduced caries experience, while no significant effect of optimal fluoride level was found for the permanent dentition (Table 5). Fluorosis was seen in 4.1% of 5–6-year-old children, in 11.8% of 12-year-old children and in 12.8% of 15-year-old children. In all three age groups, those living in the Eastern and Tarai regions and in urban locations had a significantly higher degree of fluorosis than children living in the other regions (Table 4).
Table 5.
Dental caries experience in relation to fluoride levels in drinking water
| Fluoride level (ppm) | n | Number of sample sites | dt | dmf | DT | DMF |
|---|---|---|---|---|---|---|
| <0.5 | 915 | 21 | 4.93 (4.27) | 4.97 (4.31) | 1.61 (2.03) | 1.68 (2.10) |
| 0.5 – 0.8 | 177 | 5 | 5.60 (3.89) | 5.71 (4.04) | 1.64 (2.14) | 1.66 (2.16) |
| >0.8 | 45 | 1 | 1.89 (2.53) | 1.89 (2.53) | 1.45 (2.08) | 1.48 (2.16) |
| P | 0.060 | 0.055 | 0.505 | 0.855 |
Values are given as mean (standard deviation), dt/DT, decayed primary (lowercase) or permanent (uppercase) tooth; dmf/DMF, decayed, missing or filled primary (lowercase) or permanent (uppercase) tooth.
Almost three-quarters (73.6%) of the children needed prompt treatment, while only 0.8% needed preventive treatment. About one-quarter (25.6%) needed treatment urgently. The proportion of those needing treatment urgently was significantly higher (46.2%) among those 5–6 year of age than among those 12 (14.5%) and 15 (15.1%) years of age (P < 0.001). Children from the Mountain region (P = 0.051) and the Central developmental region (P < 0.001), or belonging to the Brahaman/Chhetri ethnic group (P = 0.317) needed treatment more urgently than the children in other regions/groups.
Discussion
Epidemiological studies on oral health must be routinely conducted to monitor the trends and risks of oral diseases. The present cross-sectional study provides information on the current oral health situation among schoolchildren in Nepal, a developing country. An increasing trend in the prevalence of oral diseases among Nepalese children was found when the results were compared with the previous National Oral Health Pathfinder Survey7 conducted in Nepal. In particular, the caries and gingival status of 5–6-year-old children are alarming. The number of subjects (in each age group) and the number of sample sites in the present study is in agreement with the WHO recommendation on pathfinder surveys8. Furthermore, the 18 districts surveyed in the present study also include one metropolitan city (Kathmandu), four sub-metropolitans (Bhaktapur, Birgunj, Butwal, Lalitpur), two major cities (Mahendranagar, Nepalgunj) and 11 villages (Figure 1).
The geographical variation in oral diseases identified here supports earlier findings regarding the link between diseases, access to health services and sociodemographic background13., 14.. Indeed, including the place of residence in the analyses enhances the value of a cross-sectional study, such as this one15. In Nepal, the majority of children reported high consumption of sugar-containing foods16., 17.. Commercially produced foods enriched with fermentable carbohydrates are nowadays readily available in all parts of Nepal17. Lack of knowledge of the impact of such a harmful diet may, indeed, be one reason for poor oral health. The importance of oral health habits (mainly dietary sugar and toothbrushing) in dental caries prevalence was recently reported in a 6-year follow-up study conducted in North Korea18.
In addition to behavioural factors, the high prevalence of untreated dental caries and gingival bleeding in the Mountain and Western regions region may be a result of limited oral health promotion, lack of preventive measures and poor access to oral health services. A recent study on the dentist:population ratio in Nepal supports our findings19. Dentist density and distance to travel for oral health services have also been found to influence oral health service use and oral health behaviours20. The association between ethnicity and caries experience was evident, in the present study, mainly in indigenous (Newari and Janajati) children, and caries experience was even higher than previously reported concerning the children in Chepang21. A possible explanation for this might be the low socio-economic status and low literacy rate among Dalits and Janajati, but not among Newaris22. We can only speculate on the cause of high caries level among Newari children - perhaps dietary factors and oral hygiene habits - but this needs further investigation. These findings should be borne in mind while making health-promotion policies and planning and targeting resources.
Caries with harmful consequences was most prevalent in the primary dentition. This suggests that environmental, sociodemographic and behavioural factors pose a real risk to early childhood caries in today’s Nepal23. In all age groups, hardly any lesions had been restored, which explains the identical values obtained for mean dt/DT and dmft/DMFT. Regarding caries status, the results of epidemiological studies conducted in Sudan24, Bhutan25 and Albania26 were in concordance with those obtained in the present study, whereas the caries prevalence among Afghani27 and Lao15 children was higher. This mean that caries experience clearly reflects the increasing trend in tooth decay in low- and middle-income countries; emphasis should be put on prevention because disparities exist.
BOP was considered to indicate gingivitis28 because BOP has a good correlation with gingival index scores of 2 and 329. The results can be considered as reliable when trained and calibrated examiners probe using standard force30. The prevalence of BOP was high in general and significantly higher in rural than in urban communities, which is in concordance with the results reported in Laos15 and Brazil31 among 12-year-old subjects. Our results indicate future periodontal disease among the participants if gingival BOP is left untreated32. Interestingly, gingival BOP tended to be higher in the older age groups and among girls. This supports the impact of hormonal changes on the periodontium during puberty33.
The prevalence of dental trauma was low compared with that reported in previous studies conducted among these age groups15., 34.. Accidents and sports are known to cause tooth trauma35 and this should also be investigated in Nepal. Among the 12-year-old children, the prevalence of fluorosis was identical to findings from Sudan24.
The sample size was determined at baseline on the basis of power calculations. Despite the randomisation in the older age group, a shortcoming of the study is that the schools in each district were selected by convenience sampling, which might have led to selection bias. Furthermore, not considering the clustered design and data during analysis can be considered as a limitation of our study. Only those children in the youngest age group accompanied by their parents were included. The decision to investigate access to oral health care based on urban/rural location is appropriate because of centralisation of dental care only in major cities, which are all located in Tarai and in the Kathmandu and Pokhara valleys and not in every district.
The sample represented different ecological and developmental areas and location (urban/rural). Intra- and interexaminer agreement indicated that the outcome is reliable. Inclusion of bitewing radiographs would have been valuable, but in this case was not possible.36 However, the protocol included the rarely used pufa/PUFA index, which indicates the severity of caries status. Furthermore, the field sites, training and the protocol followed WHO guidelines and standardised validation methods8, and the agreement within and between the examiners was moderate to good for all variables37. In addition, multiple variables were included in the protocol, as suggested by the WHO8.
The Geographic Information System is an innovation that provides a complete overview on analysis of geographical variation of the disease. The inclusion of geo-mapping in the present study allowed the generation of valuable and new information on the association between residence and oral health, as performed previously in developed countries38., 39.. Geo-mapping can be used for planning and for reviewing the outcome of health policies40.
The results from the present study support and suggest the need for more effective population-based preventive programmes. The role of fluoride in preventing dental caries is well established. Cost-effective methods, such as water fluoridation and salt fluoridation, are beneficial41. However, water fluoridation is not feasible in Nepal as people use multiple sources (more than 40,000) of drinking water42. The possibility of salt fluoridation should be investigated, as there is only one salt processing company42. Brushing with fluoridated toothpaste is the most effective and widely used topical fluoride practice and has become common also in Nepal since fluoridated toothpaste became readily available in the late 1990s.43 However, the problem of affordability and accessibility of fluoridated toothpaste in Nepal still exists; all toothpastes are imported from multinational private companies and cost has remained high for ordinary citizens because of taxes. Measures to reduce the cost of fluoridated toothpaste in developing countries, including reducing taxes and producing toothpaste locally, were proposed previously by Goldman et al44. Toothbrushing frequency needs to be improved because the majority of Nepalese children report brushing their teeth only once per day16. Similarly, annual application of silver diamine fluoride45 could be integrated with the ongoing Nepal National Vitamin A Program (NVAP), which could decrease the incidence of early childhood caries. Nevertheless, the cost- and time- effective programmes must be implemented.
The original hypothesis that there is residence-related variation in the prevalence of dental caries was confirmed. Dental caries with serious consequences is common, especially among 5–6-year-old Nepalese children and particularly in the Western developmental region. In all age groups, the situation was the best in Tarai, where in three out of seven districts, the fluoride concentration was ≥0.5 ppm. This should be further investigated. Schoolchildren from the Mountain region and from the Kathmandu Valley have a higher risk for dental caries compared with children from other regions/districts. The cause of this is a matter of speculation but it may be a result of behavioural issues. Behaviour modifications, such as toothbrushing with fluoridated toothpaste and limiting sugar intake according to the WHO guidelines (to <10% of total energy), will reduce the risk of dental caries as well as other possible non-communicable diseases46. Gingival bleeding, a sign of a risk of future periodontal disease, is common throughout the country and in all age groups. Geo-mapping is a valuable tool and should be utilised in the monitoring of oral health and its risk factors in populations. In conclusion, the present study highlights the need for national oral health promotion programmes and primary health-care-based dental services in Nepal.
Acknowledgements
The authors would like to dedicate this work to Late Professor Aubrey Sheiham for his continuous support and contribution to the School Oral Health: Nepal project. This work was financially supported by the Center for International Mobility (CIMO), Finland.
Conflict of Interest
The authors declare no conflicts of interest.
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