RESEARCH ARTICLE

Associations between dental knowledge,
source of dental knowledge and oral healthbehavior in Japanese university students: A
cross-sectional study
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Ayano Taniguchi-Tabata1, Daisuke Ekuni1,2*, Shinsuke Mizutani3, Mayu YamaneTakeuchi1, Kota Kataoka1, Tetsuji Azuma1, Takaaki Tomofuji4, Yoshiaki Iwasaki5,
Manabu Morita1
1 Department of Preventive Dentistry, Okayama University Graduate School of Medicine, Dentistry andPharmaceutical Sciences, Okayama, Japan, 2 Advanced Research Center for Oral and Craniofacial
Sciences, Okayama University Dental School, Okayama, Japan, 3 Section of Geriatric Dentistry, Departmentof General Dentistry, Fukuoka Dental College, Fukuoka, Japan, 4 Department of Community Oral Health,Asahi University School of Dentistry, Gifu, Japan, 5 Health Service Center, Okayama University, Okayama,Japan* dekuni7@md.okayama-u.ac.jp

OPEN ACCESS
Citation: Taniguchi-Tabata A, Ekuni D, Mizutani S,
Yamane-Takeuchi M, Kataoka K, Azuma T, et al.
(2017) Associations between dental knowledge,
source of dental knowledge and oral healthbehavior in Japanese university students: A crosssectional study. PLoS ONE 12(6): e0179298.
https://doi.org/10.1371/journal.pone.0179298
Editor: Fernando Guerrero-Romero, Mexican
Social Security Institute, MEXICO
Received: February 27, 2017
Accepted: May 26, 2017
Published: June 8, 2017
Copyright: © 2017 Taniguchi-Tabata et al. This is
an open access article distributed under the termsof the Creative Commons Attribution License,
which permits unrestricted use, distribution, andreproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: The individual datacannot be publicly deposited or included as
supporting information due to ethical or legal
restrictions; i.e., potentially identifying or sensitive
participant information, and no permission to open
the data in the process of informed consent. The
Ethics Committee of Okayama University Graduate
School of Medicine, Dentistry and Pharmaceutical
Sciences, and Health Service Center at Okayama
University are imposing them. Interested
researchers may submit data sharing queries to

Abstract
The aim of this study was to investigate the associations between dental knowledge, thesource of dental knowledge and oral health behavior in a group of students at a university inJapan. A total of 2,220 university students (1,276 males, 944 females) volunteered toundergo an oral examination and answer a questionnaire. The questionnaire assessed dental knowledge, the source of dental knowledge and oral health behavior (e.g., daily frequency of tooth brushing, use of dental floss and regular dental checkups). The odds ratio
and 95% confidence interval for oral health behavior based on dental knowledge and sourceof dental knowledge were calculated using logistic regression models. Of the participants,
1,266 (57.0%) students obtained dental knowledge from dental clinics, followed by school(39.2%) and television (29.1%). Logistic regression analyses indicated that use of dental
floss was significantly associated with source of dental knowledge from dental clinics (P =0.006). Receiving regular dental checkups was significantly associated with source of dental
knowledge; the positive source was dental clinic (P < 0.001) and the negative sources wereschool (P = 0.004) and television (P = 0.018). Dental clinic was the most common source ofdental knowledge and associated with better oral health behavior among the Japanese university students in this study.

Introduction
In research on major chronic diseases, more emphasis has been placed on the influence of
health behavior rather than standard risk factors [1]. This concept has spread to the field of

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Source of dental knowledge and oral health behavior

Takayuki Maruyama (t-maru@md.okayama-u.ac.
jp).
Funding: The authors received no specific funding
for this work.
Competing interests: The authors have declaredthat no competing interests exist.

dentistry as well. In fact, oral diseases including periodontal disease can be prevented by adopting proper oral health behavior [2–4].
Proper oral health behavior such as tooth brushing, use of dental floss and receiving regulardental checkups prevents periodontal disease [5,6]. Furthermore, oral health behavior is also
associated with various factors including dental knowledge [7–9], attitude [8–10], lifestyle [11–13], stress [14,15], education level [16], socioeconomic status [17,18], sense of coherence [19]and self-efficacy [5]. Among these factors, we focused on dental knowledge in a previous study
and found that university students with dental knowledge practiced better oral health behavior
such as use of dental floss [20].
University students are able to obtain dental knowledge through various means. For example, a television campaign as a source of dental knowledge demonstrated a significant impact
on knowledge of periodontal health and disease in adults [21–23]. Another study also suggested that school is meaningful for oral health education of children as a source of dental
knowledge [24]. Furthermore, dental knowledge from dental clinics may be effective at modifying oral health behavior [25–27]. Therefore, there may be effective sources of dental knowledge that contribute to oral health behavior or periodontal disease. However, few studies havereported the influence of various sources of dental knowledge on oral health behavior.
According to these results, we hypothesized that both the source of dental knowledge anddental knowledge itself correlate with oral health behavior in university students. The aim of
this study was to investigate the associations between the source of dental knowledge, dental
knowledge and oral health behavior in a group of students at a university in Japan.

Materials and methods
Study population
In April 2014, first-year students (n = 2,288) at Okayama University were invited in this study
and 2,270 students received voluntary oral examinations and completed a questionnaire(response rate = 99.2%). The participants were recruited from 11 faculties (Faculties of Letters,
Education, Law, Economics, Science, Pharmaceutical Sciences, Engineering, Environmental
Science and Technology, Agriculture, Medicine and Dentistry). The inclusion criteria wereyoung adults (18–24 years old), and students who received oral examinations and completed
the questionnaire. The exclusion criteria were participants aged  25 years old and those who
had provided incomplete responses in the questionnaire. Participants aged  25 years old(n = 25) and those who had provided incomplete responses in the questionnaire (n = 25) were
excluded. Finally, data from 2,220 students (1,276 males, 944 females) were subjected toanalysis.
Informed consent was obtained verbally from each participant. The protocol of this study
was approved by the Ethics Committee of Okayama University Graduate School of Medicine,
Dentistry and Pharmaceutical Sciences (No. 808).

Questionnaire
A self-administered questionnaire was delivered by postal mail to each participant before dental examinations were conducted. In addition to sex and age, the questionnaire included thefollowing items.
Dental knowledge. Questionnaire items asked participants whether they could explain
dental terms, such as calculus, dental plaque, dental floss, sealant, periodontal disease, temporomandibular disorder, fluoride-containing mouthwash, topical application of fluoride and8020 movement [20]. “8020 movement” is a Japanese social campaign aiming to retain 20 ormore of one’s own teeth at the age of 80 [28]. Answers were given in a “yes/no” format.

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Source of dental knowledge and oral health behavior

Source of dental knowledge. Participants were also requested to state where theyacquired dental knowledge. Participants were able to indicate up to three sources from the following: dental clinic, school, television, family, internet, newspaper, acquaintance andpublication.
Oral health behavior. Participants were asked about the following oral health behavior:
daily frequency of tooth brushing ( 2 times/ 1 time); use of dental floss (yes/no); and receiving regular dental checkups during the past year (yes/no) [5,6].

Oral examination
Five dentists (D.E., A.T., S.M., M.Y-T. and K.K.) examined the participants’ periodontal status.
The periodontal status was assessed using the Community Periodontal Index (CPI) [29] using
a CPI probe (YDM, Tokyo, Japan) to evaluate six sites on each tooth (mesio-buccal, mid-buccal, disto-buccal, disto-lingual, mid-lingual and mesio-lingual). For periodontal examination,
the following 10 teeth were selected: two molars in each posterior sextant and the upper rightand lower left central incisors. As bleeding on probing (BOP) is an earlier and more sensitive
indicator of gingival inflammation than the probing depth [30], the percentage of teeth exhibiting BOP (%BOP) among the ten examined teeth was also assessed [20]. The intra- and interexaminer reliabilities, evaluated by κ statistics, of the CPI score were > 0.8.
Statistical analyses. The unpaired t test and chi-squared test were used to determine significant differences according to sex. Secondly, the chi-squared test was used to determine significant differences according to oral health behavior.
The odds ratio (OR) and 95% confidence interval (CI) were calculated using a logistic
regression model. Each oral health behavior was considered a dependent variable. The multivariate analysis included sex, age, dental knowledge and the source of dental knowledge as
independent variables. Independent variables were selected when the P value was <0.05 forthe chi-square test or unpaired t-test in each variable.
Lastly, we evaluated the significant differences in oral health behavior between the twogroups of periodontal statuses using the chi-squared test. The CPI and %BOP were divided
into the following two groups: presence of probing pocket depth (PPD)  4 mm (CPI codes 0,
1 or 2 vs. CPI codes 3 or 4) or %BOP (< 20 vs.  20) [31].
All statistical analyses were performed using SPSS (version 22.0; IBM, Tokyo, Japan) with alevel of significance set at P < 0.05.

Results
Table 1 shows the differences in parameters between males and females. Males had worse oral
health behavior than females (P < 0.01). Additionally, males had significantly less dental
knowledge of the seven terms than females (P < 0.05). More than half of the students acquired
dental knowledge from a dental clinic, followed by school and television. In contrast, newspaper, acquaintance and publication were rarely chosen as the source of dental knowledge.
There were no significant differences in dental knowledge and source of dental knowledge
between the two groups of tooth brushing frequency (Table 2). There were significant differences in dental knowledge of calculus, dental floss and sealant according to use of dental floss
and receiving regular dental checkups (P < 0.05). Participants who acquired dental knowledge
from a dental clinic reported significantly greater use of dental floss and regular dental checkups than participants who did not (P < 0.05) However, participants who acquired dental
knowledge from school or television reported significantly lower use of dental floss and regulardental checkups than participants who did not (P < 0.05).

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Source of dental knowledge and oral health behavior

Table 1. Differences in parameters between males and females.
Males

FemalesTotal

P value an = 1,276

n = 944n = 2,220

18.4 (0.7)

18.3 (0.7)

18.4 (0.7)

0.009

Two times

1,052 (82.4)

870 (92.2)

1,922 (86.6)<0.001One time

224 (17.6)

74 (7.8)298 (13.4)

Use of dental floss

Yes

139 (10.9)

153 (16.2)

292 (13.2)<0.001

Regular dental checkups

Yes

182 (14.3)

197 (20.9)

379 (17.1)<0.001

Dental plaqueYes

433 (33.9)

347 (36.8)

780 (35.1)

0.168

CalculusYes

364 (28.5)357 (37.8)

721 (32.5)<0.001

Periodontal diseaseYes

278 (21.8)

269 (28.5)

547 (24.6)<0.0018020 movement

Yes

217 (17.0)

250 (26.5)

467 (21.0)<0.001

Temporomandibular disorderYes

128 (10.0)

171 (18.1)

299 (13.5)<0.001

Dental floss

Yes

83 (6.5)

115 (12.2)

198 (8.9)<0.001

Topical application of fluorideYes

41 (3.2)

50 (5.3)

91 (4.1)

0.014

Fluoride-containing mouthwash

Yes

26 (2.0)

21 (2.2)

47 (2.1)

0.762

Sealant

Yes

15 (1.2)

25 (2.6)40 (1.8)

0.010

Dental clinic

Yes

687 (53.8)

579 (61.3)

1,266 (57.0)<0.001

SchoolYes

453 (35.5)

417 (44.2)

870 (39.2)<0.001

TelevisionYes

383 (30.0)

262 (27.8)645 (29.1)

0.246

FamilyYes

287 (22.5)

204 (21.6)

491 (22.1)

0.621

Internet

Yes

289 (22.6)

136 (14.4)

425 (19.1)<0.001

NewspaperYes

40 (3.1)

37 (3.9)77 (3.5)

0.318

AcquaintanceYes

52 (4.1)

23 (2.4)

75 (3.4)

0.035

PublicationYes

36 (2.8)

19 (2.0)55 (2.5)

0.226

Age
Oral health behavior
Tooth brushing (daily frequency)

Dental knowledge

Source of dental knowledge

Values are reported as mean (standard deviation) for age and number (percentage) for dichotomous variables.
aCompared males and females using t test or chi-square test.

https://doi.org/10.1371/journal.pone.0179298.t001

Regarding the association between oral health behavior and dental knowledge or source ofdental knowledge, the parameters that showed the significant differences in oral health behavior were partially different between males and females (Tables 3 and 4).
In logistic regression analyses, daily frequency of tooth brushing was significantly associated with sex (P < 0.001) (Table 5). Use of dental floss was significantly associated with sex(P = 0.004); having knowledge of dental floss (P < 0.001) and sealant (P = 0.048); and dental
clinic as the source of dental knowledge (P = 0.006). Regular dental checkups were significantly
associated with sex (P = 0.006), having knowledge about dental plaque (P = 0.008), calculus(P < 0.001), dental floss (P = 0.016) and sealant (P = 0.008), and the source of dental knowledge (P < 0.05). The positive source was dental clinic (P < 0.001) and the negative sourceswere school (P = 0.004) and television (P = 0.018).
The association between oral health behavior and periodontal status is shown in S1 Table.
Participants with low %BOP scores (< 20%) had significantly higher frequencies of using dental floss and regular dental checkups than participants with higher %BOP scores ( 20%)
(P < 0.001) (S1 Table).

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Source of dental knowledge and oral health behavior

Table 2. Association between oral health behavior and dental knowledge or source of dental knowledge.
Tooth brushing (dailyfrequency)

Use of dental floss

Regular dental checkups

Two times

One time

Yes

No

Yes

No

n = 1,922

n = 298n = 292n = 1,928

n = 379n = 1,841

Dental knowledge
Dental plaqueYes

682 (35.5)

98 (32.9)

126 (43.2)**654 (33.9)

138 (36.4)

642 (34.9)

CalculusYes

635 (33.0)

86 (28.9)

123 (42.1)**

598 (31.0)

173 (45.6)**

548 (29.8)

Periodontal diseaseYes

481 (25.0)

66 (22.1)

86 (29.5)*

461 (23.9)

103 (27.2)

444 (24.1)8020 movementYes

406 (21.1)

61 (20.5)60 (20.5)407 (21.1)

84 (22.2)

383 (20.8)

Temporomandibular disorderYes

266 (13.8)

33 (11.1)

37 (12.7)

262 (13.6)

59 (15.6)240 (13.0)

Dental floss

Yes

171 (8.9)

27 (9.1)

57 (19.5)**

141 (7.3)

58 (15.3)**

140 (7.6)

Topical application of fluoride

Yes

80 (4.2)

11 (3.7)

18 (6.2)

73 (3.8)

25 (6.6)*

66 (3.6)

Fluoride-containing mouthwash

Yes

43 (2.2)

4 (1.3)

11 (3.8)*

36 (1.9)

12 (3.2)

35 (1.9)

Sealant

Yes

37 (1.9)

3 (1.0)13 (4.5)**

27 (1.4)

17 (4.5)**

23 (1.2)

Dental clinic

Yes1,104 (57.4)

162 (54.4)

201 (68.8)**

1,065 (55.2)

301 (79.4)**965 (52.4)

SchoolYes

752 (39.1)

118 (39.6)

98 (33.6)*772 (40.0)

115 (30.3)**755 (41.0)

TelevisionYes

549 (28.6)

96 (32.2)

69 (23.6)*

576 (29.9)

80 (21.1)**

565 (30.7)

FamilyYes

418 (21.7)

73 (24.5)

82 (28.1)**

409 (21.1)

91 (24.0)

400 (21.7)

Internet

Yes

363 (18.9)

62 (20.8)64 (21.9)361 (18.7)

62 (16.4)

363 (19.7)

NewspaperYes

70 (3.6)

7 (2.3)9 (3.1)68 (3.5)

11 (2.9)66 (3.6)

AcquaintanceYes

62 (3.2)

13 (4.4)

13 (4.5)

62 (3.2)

9 (2.4)66 (3.6)

PublicationYes

51 (2.7)

4 (1.3)7 (2.4)48 (2.5)

7 (1.8)48 (2.6)

Source of dental knowledge

Values are reported as number (percentage).
*P < 0.05**P < 0.01, chi-square test.
https://doi.org/10.1371/journal.pone.0179298.t002

Discussion
In this study, we focused on the associations between the source of dental knowledge, dental
knowledge and oral health behavior. We found that differences in the source of dental knowledge were associated with oral health behavior in university students; that is, both positive andnegative associations between the sources and oral health behavior were observed.
The source of dental knowledge from dental clinics contributed to good oral health behavior, i.e., use of dental floss and regular dental checkups. A previous study found that oral healtheducation at dental clinics was effective at modifying oral health behavior [25–27], which was
confirmed by our results. Since dentists are important sources of oral disease prevention for
the general public [32], dental clinics could be the most effective location for university students to improve oral health behavior.
It is interesting to note that school and television were negatively associated with regulardental checkups (Table 5). Previous studies found that oral health education in primary or secondary school could improve oral health behavior [33–39]. On the other hand, other studies inschool-based education programs found no improvement [40,41]. A mass media health education campaign on television could not demonstrate a significant impact on behavior [42,43].
Furthermore, a recent study suggests that oral health program without repetition could transiently improve oral health behavior, but could not sustain improved oral health behavior in
the long-term [44]. Thus, oral health education should be repeated with either method to keep

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Source of dental knowledge and oral health behavior

Table 3. Association between oral health behavior and dental knowledge or source of dental knowledge in males.
Tooth brushing (daily frequency)

Use of dental floss

Regular dental checkup

Two times

One time

Yes

No

Yes

No

n = 1,052

n = 224n = 139n = 1,137

n = 182n = 1,094

Dental knowledge
Dental plaqueYes

364 (34.6)

69 (30.8)

63 (45.3)*

370 (32.5)

76 (41.8)*357 (32.6)

CalculusYes

303 (28.8)

61 (27.2)

55 (39.6)*

309 (27.2)

84 (46.2)**

280 (25.6)

Periodontal diseaseYes

232 (22.1)

46 (20.5)

38 (27.3)

240 (21.1)

45 (24.7)

233 (21.3)

8020 movement

Yes

177 (16.8)

40 (17.9)

23 (16.5)

194 (17.1)

30 (16.5)

187 (17.1)

Temporomandibular disorderYes

109 (10.4)

19 (8.5)

17 (12.2)

111 (9.8)

22 (12.1)

106 (9.7)

Dental flossYes

65 (6.2)

18 (8.0)

18 (12.9)*

65 (5.7)

26 (14.3)**

57 (5.2)

Topical application of fluorideYes

35 (3.3)

6 (2.7)6 (4.3)35 (3.1)

11 (6.0)*30 (2.7)

Fluoride-containing mouthwash

Yes

22 (2.1)

4 (1.8)7 (5.0)*19 (1.7)

8 (4.4) *18 (1.6)

Sealant

Yes

14 (1.3)

1 (0.4)3 (2.2)

12 (1.1)

5 (2.7)*10 (0.9)

Source of dental knowledge
Dental clinic

Yes

569 (54.1)

118 (52.7)

92 (66.2)*

595 (52.3)

135 (74.2)**552 (50.5)

SchoolYes

369 (35.1)

84 (37.5)

44 (31.7)

409 (36.0)

57 (31.3)

396 (36.2)

TelevisionYes

313 (29.8)

70 (31.3)

36 (25.9)347 (30.5)

38 (20.9)*345 (31.5)

FamilyYes

230 (21.9)

57 (25.4)

36 (25.9)

251 (22.1)

41 (22.5)

246 (22.5)

Internet

Yes

238 (22.6)

51 (22.8)

34 (24.5)

255 (22.4)

40 (22.0)249 (22.8)

NewspaperYes

35 (3.3)

5 (2.2)4 (2.9)36 (3.2)

7 (3.8)33 (3.0)

AcquaintanceYes

40 (3.8)

12 (5.4)

9 (6.5)43 (3.8)

4 (2.2)48 (4.4)

PublicationYes

33 (3.1)

3 (1.3)5 (3.6)31 (2.7)

5 (2.7)31 (2.8)

Values are reported as number (percentage).
*P < 0.05**P < 0.01, chi-square test.
https://doi.org/10.1371/journal.pone.0179298.t003

its positive results [41,44,45]. Taken together, the other sources except for dental clinics might
not encourage regular dental checkups repeatedly.
A previous study found that oral health education from school teachers or dentists wasequally effective in improving oral health knowledge and the oral hygiene status of adolescents[46]. However, the outcome of oral health education programs is dependent on the teachers’
instructions or motivations [47–49]. This finding may support our result that obtaining dental
knowledge from school was negatively associated with receiving regular dental checkups.
On the other hand, multifaceted interventions such as education programs, with a combination of methods (lectures and small-group discussions), improved knowledge, skills and attitude compared to single interventions or no interventions [50]. In terms of an education
program, “television”, “family”, “internet”, “newspaper”, “acquaintance” or “publication”
involved no intervention, but “school” can have multifaceted interventions. This study demonstrated that school was one of the major sources of dental knowledge. However, school was
negatively associated with oral health behavior. Therefore, more effective intervention to promote better oral health behavior among students should be introduced in the Japanese education curriculum.
In this study, the most common source of dental knowledge was dental clinic, followed byschool. However, approximately 20 years ago, schools were the most common source of dental
knowledge in Japan [24]. In other countries, more than 60% of adults obtained dental knowledge from dentists or dental clinics [32, 51]. Furthermore, in the United States and other western countries, adults visited the dental clinic more often [52–54]. In Japan, the rate of regular

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Source of dental knowledge and oral health behavior

Table 4. Association between oral health behavior and dental knowledge or source of dental knowledge in females.
Tooth brushing (dailyfrequency)

Use of dental floss

Regular dental checkup

Two times

One time

Yes

No

Yes

No

n = 870n = 74n = 153n = 791n = 197n = 747

Dental knowledge
Dental plaqueYes

318 (36.6)

29 (39.2)

63 (41.2)

284 (35.9)

62 (31.5)285 (38.2)

CalculusYes

332 (38.2)

25 (33.8)

68 (44.4)289 (36.5)

89 (45.2)*

268 (35.9)

Periodontal diseaseYes

249 (28.6)

20 (27.0)

48 (31.4)

221 (27.9)

58 (29.4)

211 (28.2)8020 movement

Yes

229 (26.3)

21 (28.4)

37 (24.2)

213 (26.9)

54 (27.4)

196 (26.2)

Temporomandibular disorderYes

157 (18.0)

14 (18.9)

20 (13.1)

151 (19.1)

37 (18.8)

134 (17.9)

Dental floss

Yes

106 (12.2)

9 (12.2)

39 (25.5)**

76 (9.6)

32 (16.2)

83 (11.1)

Topical application of fluorideYes

45 (5.2)

5 (6.8)12 (7.8)

38 (4.8)

14 (7.1)

36 (4.8)

Fluoride-containing mouthwash

Yes

21 (2.4)0 (0)4 (2.6)17 (2.1)

4 (2.0)17 (2.3)

Sealant

Yes

23 (2.6)

2 (2.7)

10 (6.5)*

15 (1.9)

12 (6.1)*

13 (1.7)

Source of dental knowledge
Dental clinic

Yes

535 (61.5)

44 (59.5)

109 (71.2)*

470 (59.4)

166 (84.3)**

413 (55.3)

SchoolYes

383 (44.0)

34 (45.9)

54 (35.3)*

363 (45.9)

58 (29.4)**359 (48.1)

TelevisionYes

236 (27.1)

26 (35.1)

33 (21.6)

229 (29.0)

42 (21.3)*

220 (29.5)

FamilyYes

188 (21.6)

16 (21.6)

46 (30.1)*

158 (20.0)

50 (25.4)

154 (20.6)

Internet

Yes

125 (14.4)

11 (14.9)30 (19.6)*

106 (13.4)

22 (11.2)

114 (15.3)

NewspaperYes

35 (4.0)

2 (2.7)5 (3.3)32 (4.0)

4 (2.0)33 (4.4)

AcquaintanceYes

22 (2.5)

1 (1.4)4 (2.6)19 (2.4)

5 (2.5)18 (2.4)

PublicationYes

18 (2.1)

1 (1.4)2 (1.3)17 (2.1)

2 (1.0)17 (2.3)

Values are reported as number (percentage).
*P < 0.05**P < 0.01, chi-square test.
https://doi.org/10.1371/journal.pone.0179298.t004

dental checkups has been increasing [55]. Thus, the source of dental knowledge may change
from school to dental clinics.
The percentage of participants who could explain dental floss was different from that of participants who used dental floss. The previous study shows that the percentage of participants
who comprehend dental floss was different to that of participants who used dental floss [56].
Thus, explainable level of dental knowledge might not completely imply oral health behavior.
On the other hand, dental knowledge of dental floss was positively associated with use of dental
floss, which was supported by the previous study [56]. As the relationship between knowledge
and behavior can be complex, further studies are needed.
In our study, use of dental floss and receiving regular dental checkups were associated with
%BOP (S1 Table); that is, participants with good oral health behavior had good periodontal
status. This result supports the findings of a previous study [6]. Thus, acquiring dental knowledge from dental clinics may effectively induce good oral health behavior, which contributes
to achieving and maintaining good periodontal status.
There are some limitations associated with our study. First, a causal association could not
be shown because the study was cross-sectional. Second, other possible confounders, such as
attitude [9–10], lifestyle [11–13], stress [14,15], education level [16], socioeconomic status[17,18], sense of coherence [19] and self-efficacy [5], were not included in this study. Third, we
did not investigate the effects of frequency of obtaining information from the source, interaction between the assessed knowledge and the sources, frequency of dental floss use, the recall

PLOS ONE | https://doi.org/10.1371/journal.pone.0179298 June 8, 20177 / 11

Source of dental knowledge and oral health behavior

Table 5. Adjusted OR and 95% CIs for oral health behavior.
Use of dental floss

Tooth brushing (dailyfrequency)
Two times per day
Age
Sex

Regular dental checkups

Yes

Yes

OR

95% CI

P valueOR

95% CI

P valueOR

95% CI

P value

1.02

0.85–1.21

0.856

1.08

0.92–1.26

0.362

0.98

0.84–1.15

0.789

1.10–1.75

0.007

0.51–0.90

0.008

1.47–2.53<0.001

0.65–1.17

0.379

1.09–2.30

0.016

0.67–1.99

0.600

0.58–2.57

0.594

1.27–5.03

0.008

2.22–3.85<0.001

0.53–0.89

0.004

0.54–0.94

0.018

0.74–1.29

0.872

Male

1.00

Female

2.52

No

1.00

Yes

1.09

No

1.00

Yes

1.08

Periodontal disease

No

1.00

Yes

1.08

Dental floss

No

1.00

Yes

0.75

Topical application of fluoride

No

1.00

Yes

0.90

No

1.00

Yes

1.68

No

1.00

Yes

1.67

No

1.00

Yes

1.02

School

No

1.00

Yes

0.88

Television

No

1.00

Yes

0.84

Family

No

1.00

Yes

0.83

1.00
1.90–3.34<0.001

0.80–1.48

0.597

0.79–1.49

0.614

1.45

1.00
1.12–1.87

0.004

1.39

0.84–1.52

0.418

0.68

0.88–1.61

0.259

1.93

Dental knowledge
Dental plaqueCalculus

Fluoride-containing mouthwash
Sealant

1.00
1.13

1.00

1.00
1.19

1.00

1.00
0.77–1.50

0.656

0.96

1.00
0.70–1.32

0.815

1.00
0.47–1.19

0.219

2.30

1.00
1.58–3.35<0.0011.00
0.45–1.82

0.773

0.57–4.94

0.345

0.83

0.46–1.51

0.543

1.16

0.73–3.29

0.250

1.22

1.00

1.00
0.50–5.55

0.406

0.79–1.32

0.868

2.06

1.58
1.00

1.00
1.55

0.88

1.00
1.01–4.20

0.048

2.53

1.12–1.94

0.006

2.92

Source of dental knowledge
Dental clinic

1.00
1.47

1.00

1.00
0.68–1.14

0.319

0.79

1.00
0.60–1.03

0.083

1.00
0.64–1.11

0.219

0.78

1.00
0.58–1.06

0.110

1.00
0.62–1.11

0.219

1.30

0.69
0.71
1.00

0.97–1.73

0.077

0.98

Adjusted for age, sex, dental knowledge and source of dental knowledge.
https://doi.org/10.1371/journal.pone.0179298.t005

interval for the dental checkups, the experience and pattern of dental visitation, or the relation
between oral health status and dental visitation pattern, which might affect oral health behavior. Finally, all participants were recruited from Okayama University students. It may limit theability to extrapolate these findings to the general young population.

Conclusion
The source of dental knowledge from dental clinics as well as having dental knowledge wereassociated with better oral health behavior in university students in Japan.

Supporting information
S1 Table. Association between oral health behavior and periodontal status.
(DOCX)PLOS ONE | https://doi.org/10.1371/journal.pone.0179298 June 8, 20178 / 11

Source of dental knowledge and oral health behavior

Acknowledgments
The authors thank Dr. Muneyoshi Kunitomo, Hirofumi Mizuno and Hisataka Miyai (Department of Preventive Dentistry, Okayama University Graduate School of Medicine, Dentistry
and Pharmaceutical Sciences, Okayama, Japan) for helping with data entry.

Author Contributions
Conceptualization: DE SM MM.
Data curation: AT-T DE SM.
Formal analysis: AT-T.
Investigation: AT-T DE SM MY-T KK TA.
Methodology: AT-T DE SM TT MM.
Project administration: AT-T DE MM.
Resources: AT-T.
Supervision: MM.
Validation: AT-T.
Visualization: AT-T.
Writing – original draft: AT-T.
Writing – review & editing: AT-T DE SM MY-T KK TA TT YI MM.

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