Current Pediatric Research

Research Article - Current Pediatric Research (2017) Volume 21, Issue 4

Study on DMFT related factors in some adolescents.

Yu-Hee Lee1and Jung-Ok Choi2*

1Division of Public Health, Graduate School of Inje University, Busan, 47392, Korea.

2Department of Dental Hygiene, Youngsan University, Yangsan, 50510, Korea.

*Corresponding Author:
Jung-Ok Choi, Assistant Professor
Youngsan University, Dental Hygiene
5611, Sanhakgwan, 288, Junam-ro
Yangsan, Gyeongsangnam-do 50510
Republic of Korea.
E-mail: [email protected]

Accepted date: December 18, 2017

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Objective: The objective of this study is to analyze the effects of oral health care behaviors on decayed, missing and filled teeth (DMFT) in some Korean adolescents. Methods: For this study, the data of the Korea National Health and Nutrition Examination Survey (KNHANES) VI-3 (2015) were used. The study subjects included a total of 463 adolescents aged 12 to 19 years. The data were analyzed with the SPSS program. For general and oral-related characteristics, descriptive statistics and for determination of the relationship, the correlation analysis and multiple regression analysis were performed. Results: The DMFT index tended to change with age, income level which was found to be an important factor affecting DMFT. In addition, sex, age, BMI, income level, tooth brushing, floss, interdental brush, gargle was significant in the correlation analysis between DMFT and each items. Conclusions: Dental caries, one of the major oral diseases, is active in adolescence and it is very important to form oral care habits at this time and develop oral care programs based on the findings.


Adolescents, Age, DMFT, Oral health.


Adolescence is a time of transition from childhood to adulthood, with physical, psychological, and social characteristics. In particular, at this time, dietary habits and oral hygiene management are not controlled by the caregiver, and oral care is neglected by various problems such as peer relationship, study and appearance. Thus, it is known that adolescents become susceptible to oral diseases [1]. In adolescence, dental caries, which is known as one of the two major oral diseases, frequently occurs, and it is important to acquire the method to maintain oral health through education [2]. These backgrounds are supported by studies having reported that adolescents gradually have a perception of health and form health beliefs through behaviors or attitudes, which makes an influence throughout their lifetime [3,4].

Dental caries is a dental hard tissue disease, in which demineralization is caused, and organic matter is destructed, thereby resulting in the defect of tooth structure. It is also the largest cause of tooth loss in adolescence [5,6]. Once dental caries occurs, the tooth cannot be returned to the original condition, and it increases with age. To prevent this, there should be changes in the knowledge, attitude and behavior along with tooth brushing and use of oral hygiene aids [7].

WHO uses the DMFT index as a diagnostic criterion to assess the level of experience of dental caries, which is calculated by summing the numbers of teeth that experienced dental caries progression, dental loss by dental caries, and dental caries treatment [8]. It is the most commonly used and the most common standard in clinical practice. According to the National Oral Health Survey conducted in Korea, the DMFT index in 12 year old children tends to decrease gradually from 2.86 in 2000 to 2.16 in 2006 and 2.1 in 2010 [9]. In addition, dental caries has been reported to take 8th place in the frequent disease ranking in Korea in 2010, holding a high rank among dental diseases [10]. Dental caries is an important factor in evaluating oral health, and it is obviously one of the serious oral diseases.

Therefore, this study aimed to determine the effects of various behaviors for the oral health of adolescents on the DMFT index based on the Korea National Health and Nutrition Examination Survey (KNHANES) and to prepare fundamental data for the education on dental caries management for oral disease prevention of adolescents.

Materials and Methods

Study Subjects

The Korea National Health and Nutrition Examination Survey (KNHANES) VI-3 (2015) were used as law data. 463 adolescent samples aged 12 to 19 years old were extracted and were included without missing items in this study.

Study Method

This study was used sex, age, body mass index, income level, health insurance, tooth brushing, dental floss, interdental toothbrush, gargle solution, oral examination, visiting dental clinic and DMFT variables based on the data of KNHANES VI-3.

The data of Gender, age, use of oral health products were analyzed without conversion. Age was not divided individually, but 12 to 15 years old and 16 to 19 years old. The body mass index was classified into 'underweight' for a BMI below 18.5, ‘normal’ for a BMI of 18.5 or higher and below 23.0, ‘overweight’ for a BMI of 23.0 or higher and below 25.0, and ‘obesity’ for a BMI of 25.0 or higher. The data related to family income were separated by income quintiles. The data of DMFT index was calculated with based on the presence or absence simply.

Statistical Analysis

This study used the original data of the KNHANES VI-3, we conducted a composite sample analysis. And the composite sample design was made by applying the questionnaire and examination survey. Frequency analysis and descriptive statistics were performed to confirm the general characteristics and oral characteristics of the subjects, and chi - square tests were performed to confirm DMFT according to general characteristics and oral characteristics. Correlation analysis was performed to investigate the relationship of related variables and multiple logistic regression analysis was performed to identify the factors affecting DMFT. For statistical analysis of this study, SPSS ver. 24.0 (IBM corp., Armonk, NY, USA) was used.


General Characteristics of the Subject

In order to identify the general characteristics of the subjects, the frequencies and descriptive statistics were calculated.

Of the total 463 subjects, there were 253 males (52.2%) and 210 females (47.8%). In terms of age, 287 subjects (56.7%) were between 12 and 15 years old, and 176 subjects (43.3%) were between 16 and 19 years old. Income level was the highest among the fourth quintile as 159 (32.1%). Most of the subjects were covered by work type of health insurance. In terms of BMI, 87 subjects (17.6%) were low weight, 240 subjects (53.2%) were normal, 57 subjects (11.5%) were overweight and 79 subjects (17.6%) were obese (Table 1).

Variables Group N (%)
Sex Male 253 (52.2)
Female 210 (47.8)
Age 12-15 287 (56.7)
16-19 176 (43.3)
Income level Low 55 (13.8)
Middle low 112 (25.4)
Middle high 159 (32.1)
High 137 (28.6)
Health insurance Regional type 129 (30.5)
Work type 300 (61.2)
Medicaid 29 (7.4)
No 5 (0.9)
BMI Low weight 87 (17.6)
Normal 240 (53.2)
Overweight 57 (11.5)
Obesity 79 (17.6)

Table 1. General characteristics.

Oral-Related Characteristics of the Subject

In order to identify the oral-related characteristics of the subjects, the frequencies and descriptive statistics were calculated.

The number of tooth brushing was 0-1 time in 49 subjects (10.0%); 2 times in 182 subjects (39.9%); 3 times in 173 subjects (35.8%), and 4 times or more in 63 subjects (14.3%). In terms of the yesterday tooth brushing status, 16 subjects (3.0%) did not brush their teeth, while 451 subjects (97.0%) brushed their teeth. As for the use of dental floss, 422 subjects (91.7%) did not use dental floss, and 45 subjects (8.3%) did. As for the use of interdental brush, 419 subjects (90.3%) did not use interdental brush, and 48 subjects (9.7%) did. In terms of the use of mouthwash, 396 subjects (85.0%) did not use mouthwash and 71 subjects (15.0%) did.

215 subjects (45.0%) who received oral examination for one year were slightly less than half. A total of 261 subjects (55.4%) visited the dental clinic during the year.

Additionally, as for the dental caries experience in permanent teeth, among the 467 adolescents, 190 subjects (38.6%) did not experience dental caries and 277 subjects (61.4%) experienced dental caries (Table 2).

Variables N (%)
Tooth brushing frequency 0-1 49 (10.1)
2 178 (39.3)
3 173 (36.1)
4 or more 63 (14.4)
Tooth brushing/1 day No 16 (3.0)
Yes 447 (97.0)
Use of floss No 418 (91.6)
Yes 45 (8.4)
Use of interdental brush No 416 (90.4)
Yes 47 (9.6)
Use of gargle No 392 (84.9)
Yes 71 (15.1)
Oral examination/1 year No 248 (55.0)
Yes 215 (45.0)
Visiting dental clinic/1 year No 202 (44.6)
Yes 261 (55.4)
DMFT No 187 (38.2)
Yes 276 (61.8)

Values are presented as number (weighted %) or mean ± standard error.

Table 2. Oral characteristics.

Comparison of DMFT According to General Characteristics

The chi-square analysis was performed to test whether there was a difference in the presence of DMFT depending on the general characteristics of the subjects. The result is presented in Table 3.

Variables DMFT p*
No Yes
Sex Male 107 (39.7) 146 (60.3) 0.535
Female 80 (36.6) 130 (63.4)
Age 12-15 139 (48.2) 148 (51.8) 0.000**
16-19 48 (25.1) 128 (74.9)
Income level Low 14 (24.6) 41 (75.4) 0.005*
Middle low 40 (30.9) 72 (69.1)
Middle high 64 (39.0) 95 (61.0)
High 69 (50.5) 68 (49.5)
Health insurance Regional type 46 (35.2) 83 (64.8) 0.096
Work type 134 (42.6) 166 (57.4)
Medicaid 5 (15.4) 24 (84.6)
No 2 (27.5) 3 (72.5)
BMI Low weight 36 (40.2) 51 (59.8) 0.395
Normal 101 (40.9) 139 (59.1)
Overweight 20 (35.6) 37 (64.4)
Obesity 30 (30.0) 49 (70.0)

Table 3.DMFT according to general characteristics

The age and Income level were both higher in the group with DMFT than in the group without DMFT. Among them, there was a significant difference in the DMFT between the age groups of 12 to 15 years old and 16 to 19 years old (p=0.000). Comparisons the fourth quartile of income, the results are also significant (p=0.005).

Comparison of DMFT According to Oral Characteristics

The chi-square analysis was performed to test whether there was a difference in the presence of DMFT depending on the oral-related characteristics. The result is presented in Table 4. In the result of comparison for the presence of DMFT according to the use of dental floss, interdental brush, and mouthwash, the subjects who did not use oral hygiene aids were more likely to experience DMFT than those who used them. Among them, there were statistically significant differences in tooth brushing for a day (0.008), the use of mouthwash (0.009).

Variables DMFT p*
No Yes
Toothbrushing frequency 0-1 26 (49.0) 23 (51.0) 0.346
2 63 (35.2) 115 (64.8)
3 74 (36.7) 99 (63.3)
4 or more 24 (42.8) 39 (57.2)
Toothbrushing/ 1 day No 11 (71.6) 5 (28.4) 0.008*
Yes 176 (37.2) 271 (62.8)
Use of floss No 171 (38.7) 247 (61.3) 0.538
Yes 16 (33.3) 29 (66.7)
Use of interdental brush No 167 (38.4) 249 (61.6) 0.809
Yes 20 (36.5) 27 (63.5)
Use of gargle No 169 (40.7) 223 (59.3) 0.009*
Yes 18 (24.2) 53 (75.8)
Oral examination
/ 1 Year
No 94 (35.7) 154 (64.3) 0.261
Yes 93 (41.3) 122 (58.7)
Visiting dental clinic / 1 Year No 84 (39.9) 118 (60.1) 0.562
Yes 103 (36.9) 158 (63.1)

Table 4. DMFT according to oral characteristics.

Correlation between DMFT and Related Variables

The analysis result for determining the relationship between related variables is shown in Table 5. As a result of correlation analysis between 12 general and oral-related characteristics and DMFT, significant correlations were shown in 10 items. Among them, the income level showed a negative correlation.

Variables DMFT
Sex 0.099**
Age 0.255**
Income level -0.042*
Health insurance -0.007
BMI 0.346**
Tooth brushing frequency 0.053**
Tooth brushing/1 day 0.045**
Use of floss 0.086**
Use of interdental brush 0.027*
Use of gargle 0.064**
Oral examination/1 year -0.002
Visiting dental clinic/1 year 0.037**

Table 5. The relevance among variables.

Factors Affecting the Presence or Absence of DMFT

Multiple regression analysis was performed for general characteristics and oral characteristics and only corrected values were shown as follows. The age group was a factor that significantly affected the presence of DMFT (P=0.000). As for gargle solution, the OR of unused gargle (95% CI) was 2.40 (1.30-4.42) compared to used gargle, though it was significant. As for income level, compared to high, the OR of middle high (95% CI) was 0.52 (0.32- 0.84), the OR of middle low was 0.35 (0.18-0.66) and the OR of low was 0.41 (0.17-0.97) (Table 6).

Variables OR (95% CI) p*
Age 12-15 (Reference) 0.000*
16-19 2.81 (1.71-4.62)
Gargle Yes  (Reference) 0.005*
No 2.40 (1.30-4.42)
Income level High  (Reference) 0.004*
Middle high 0.52 (0.32-0.84)
Middle low 0.35 (0.18-0.66)
Low 0.41 (0.17-0.97)

Table 6.Factors affecting the presence or absence of DMFT ..


In adolescence, the permanent dentition is completed after the mixed dentition period. It is important to manage the permanent teeth that are erupted at this time, and as an oral-related emotional characteristic, it is essential to have knowledge, attitude and behavior about oral health. The factors causing dental caries that frequently occurs at this time are very complex and multiple and multidimensional analysis is required for prevention [11].

In terms of the number of tooth brushing of the subjects, twice a day accounted for the highest proportion at 39.3% and 3% of the subjects answered that they did not brush yesterday for the whole day. With regard to the use of oral hygiene aids, dental floss was 8.4%, and mouthwash was 15.1%. The result of the frequency of tooth brushing was consistent with that of Ma et al. [12] and the result of the use of oral hygiene aids was similar to that of Kim et al. [13] in the use of mouthwash. In addition, Lim et al. [14] reported that the use of oral hygiene aids was effective in inhibiting bleeding and tartar formation.

In this study, in terms of the relationship between general characteristics and the presence of DMFT, there was a significant difference in DMFT depending on age. Dental caries continues to increase since the permanent teeth first erupt at age 6 and more than 80% of adults experience it. It is reported that the DMFT index also increases with age [12]. This result seems to be consistent with the result that dental caries in permanent teeth also increases with age in adolescence. Moreover, there was a significant difference depending on the yesterday’s tooth brushing status. This result supports the previous studies having reported that adolescents have a high intake of sugar, which affects dental caries, and nonfulfillment of tooth brushing, which is the most basic of oral hygiene management, leads to dental caries [15]. The use of mouthwash, one of oral hygiene aids, was found to affect DMFT and it has been reported that the effect of the mouthwash is exhibited due to the control of microbial activity that causes many diseases in the mouth [16]. Proper use of these oral hygiene aids can manage dental plaque in the areas where it is difficult to remove dental plaque by general tooth brushing, thereby reducing dental caries.

As a result of the correlation analysis with DMFT, it was confirmed that dental caries is not caused by one factor as described above. The multiple regression analysis on DMFT showed that the DMFT index was 2.81 times higher in 16~19 years old compared to 12~15 years old. This was similar to the report of the Ministry of Health and Welfare that as age increases, the DMFT index increases, which is statistically significant [5,17]. On the other hand, Kim [18] reported that gender was a related factor, and male students had a higher DMFT index than female students, but this was not consistent with the result of the present study. In this study, DMFT is lowered as the income level is lowered. The results of other studies show that the lower the income level was found to have a poor oral health status and this is in contrast to the results of this study [19,20]. These results were unexpected, probably because the subject of this study is adolescents and not a subject of direct economic activity. Therefore, it is interpreted that there are various and complex factors affecting DMFT in addition to economic income level.

DMFT-related studies have been performed not only domestically but also internationally, and the present study is also expected to provide data to evaluate the trend of dental caries [21-23].

The proper management of dental caries is to remove the risk factors and one of them is proper tooth brushing and use of oral hygiene aids. This study was also conducted to identify the relationship between oral care behaviors and DMFT. It is thought that oral hygiene should be thoroughly managed through education about oral care by identifying the characteristics of adolescents.


This study was conducted to investigate the relationship between oral health behaviors and the presence of DMFT in adolescents aged 12 to 19 years old using the raw data of the Korea National Health and Nutrition Examination Survey (KNHANES) VI-3 (2015). As a result, the following conclusion was obtained. First, the DMFT index increased significantly with age and the use of oral hygiene aids led to more effective dental caries prevention compared to brushing teeth without using them. Therefore, it was confirmed that dental caries can be sufficiently prevented if appropriate oral hygiene management is carried out.


This work was supported by a 2017 research grant from Youngsan University, Republic of Korea.