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Analysis of the Effect of Daily Water Intake on Oral Health: Result from Seven Waves of a Population-Based Panel Study - MDPI
water
Article
Analysis of the Effect of Daily Water Intake on Oral Health:
Result from Seven Waves of a Population-Based Panel Study
Yu-Rin Kim

                                          Department of Dental Hygiene, Silla University, 140 Baegyang-daero, 700 beon-gil, Sasang-gu,
                                          Busan 46958, Korea; dbfls1712@hanmail.net; Tel.: +82-10-6686-8130

                                          Abstract: Proper moisture is an essential condition for maintaining the homeostasis of the body,
                                          enhancing immunity, and preventing constipation, and it is an indispensable substance for main-
                                          taining human life and health. As the bacteria that cause oral disease are affected by water intake,
                                          there is a strong relationship between water intake and oral disease. Therefore, the purpose of
                                          this study is to determine the effect of daily water intake on oral disease. The data analyzed were
                                          from a seven-year period (2010–2017) from the National Health and Nutrition Survey, conducted
                                          annually by the Korea Centers for Disease Control and Prevention. Out of a total of 48,422 people,
                                          134 people in the ‘7 cups’ group were selected as subjects. Each time a person drank
                                          one less cup of water per day, the prevalence of periodontal disease increased by 1.018 times, the
                                          prevalence of dental caries increased by 1.032 times, and the experience of dental caries increased by
                                          1.075 times. Even in Model 2, for which age and gender were adjusted, there was a significant effect.
                                          In addition, there was a significant impact in Model 3, which adjusted for oral health behavior, except
         
                                   for permanent caries prevalence. Based on the above results, oral health behavior and state were
                                          positive in those who consumed more water per day. Therefore, it is suggested that the government’s
Citation: Kim, Y.-R. Analysis of the
                                          active promotion of water intake recommendations and policies should be prepared to include water
Effect of Daily Water Intake on Oral
                                          intake as a component of improving oral health.
Health: Result from Seven Waves of a
Population-Based Panel Study. Water
2021, 13, 2716. https://doi.org/          Keywords: habits; oral health; periodontal disease; self-care; water
10.3390/w13192716

Academic Editor: Vincenzo
Romano Spica                              1. Introduction
                                                Water accounts for 60% of an adult’s weight. Roughly 70% of the water is distributed
Received: 19 August 2021                  within the cells, while the rest is distributed outside the cells in the form of epilepsy,
Accepted: 25 September 2021
                                          plasma, lymphatic fluid, and other body fluids [1]. This water transports nutrients and
Published: 1 October 2021
                                          waste products as major components of blood and acts as a solvent for various biochemical
                                          reactions in the body [2]. In addition, it controls body temperature in the form of sweat,
Publisher’s Note: MDPI stays neutral
                                          digests food as a component of various digestive fluids, and acts as a lubricant to smoothly
with regard to jurisdictional claims in
                                          move joints and internal organs in the form of synovial fluid and mucus [3,4]. Water
published maps and institutional affil-
                                          also plays a role in protecting the internal organs and fetus in the cerebrospinal fluid and
iations.
                                          amniotic fluid of pregnant women. Therefore, proper moisture is an essential condition for
                                          maintaining the homeostasis of the body, enhancing immunity, and preventing constipation,
                                          and it is an indispensable substance in maintaining human life and health [5]. When the
                                          balance of water is broken or the body lacks too much water, the human body exhibits
Copyright: © 2021 by the author.          a dehydration reaction. If 2% of the total amount of water in the body decreases, we
Licensee MDPI, Basel, Switzerland.
                                          feel thirst, and if it decreases by 2–4%, muscle fatigue is easily induced, and motor and
This article is an open access article
                                          cognitive functions are reduced. If more than 10% is lost, fatal organ damage and clinical
distributed under the terms and
                                          shock can result and put a life at risk, whereas a loss of more than 15–20% can worsen
conditions of the Creative Commons
                                          dehydration, thereby leading to death [6,7]. Without water, humans can only survive for
Attribution (CC BY) license (https://
                                          2–4 days [5,8,9]; therefore, maintaining adequate moisture is very important. Since 5–10%
creativecommons.org/licenses/by/
4.0/).
                                          of water must be exchanged every day, the amount of water required per day depends on

Water 2021, 13, 2716. https://doi.org/10.3390/w13192716                                                       https://www.mdpi.com/journal/water
Water 2021, 13, 2716                                                                                            2 of 10

                       body weight, temperature, activity, and body calorie consumption [10–13]. As such, the
                       total amount of water intake that must be supplied to our body from the outside is 1–3 L,
                       thereby indicating a wide range [14,15]. Although it is recommended to consume 30 mL
                       per kg of body weight [16] or 1 mL of water per kilocalorie [12], the amount of water that
                       adults consume through water or beverages per day is reported as an average of 2 L [17].
                       Moreover, as age increases, the intake of water decreases, leading to increased vulnerability
                       to many diseases [18]. Lack of water can cause systemic problems, as well as various
                       health-related symptoms in the oral cavity, such as dry mouth, burning in the mouth due
                       to thirst, or low saliva secretion. If these symptoms persist, it can become an environment
                       that causes oral disease [19]. Saliva is not only necessary to maintain the normal function of
                       oral tissues, but also to suppress oral disease occurrence, and if salivary secretion decreases
                       below normal levels, it can cause oral mucosal diseases and oral diseases. When salivation
                       is lowered, salivary buffering capacity and saliva pH are lowered, and this can significantly
                       cause and increase dental caries [20].
                             Dental diseases are broadly classified into dental caries and periodontal diseases, both
                       of which are caused by microbial infection. Among more than 500 kinds of bacteria present
                       in the oral cavity, the microbe that is most closely related to dental caries is Streptococcus
                       mutans (S. mutans), a decisive causative agent that induces tooth decay by damaging
                       the hard structure of the teeth [20–22]. Prevotella intermedia (P. intermedia), one of the
                       major pathogens of periodontal disease, is known to be a powerful causative agent of
                       adult periodontitis, pregnancy gingivitis, and ulcerative gingivitis [23,24], and it has been
                       reported to be found in oral lesions [22,23]. These bacteria are affected by the amount
                       of water intake; the prevalence of P. intermedia, in particular, decreased as the amount of
                       water intake increased [25]. In Hong’s [20] study, it was reported that less P. intermedia
                       causing the periodontal disease was detected in the group drinking 3 to 4 glasses of water
                       per day, and Jung et al. [25] reported that dental caries-causing S. mutans were detected
                       in the group with the least water intake. However, these differences were not significant
                       results and need to be re-confirmed. Therefore, it is necessary to evaluate the relationship
                       between dental caries and periodontal disease according to the amount of water ingested
                       per day. The majority of studies previously conducted have examined the relationship
                       between water intake and systemic diseases [3–9] and on water intake relationships in the
                       elderly [18,25]. Furthermore, there are few studies on the relationship between oral health
                       behavior and oral health state in all age groups. Therefore, this study aims to compare
                       demographic characteristics, oral health behaviors, and oral health state according to the
                       amount of water intake by using the 7-year data from the National Health and Nutrition
                       Survey, which represents the Korean people, and identify the substantial impact of water
                       intake on periodontal disease and dental caries in order to use the results as fundamental
                       data confirming the importance of water intake.

                       2. Materials and Methods
                       2.1. Study Design
                            Data for seven years (2010–2017) from the National Health and Nutrition Survey
                       conducted annually by the Korea Centers for Disease Control and Prevention were ana-
                       lyzed. Before analyzing the panel survey, we accounted for varying sample sizes from
                       2010 to 2017 and missing values of variables to ensure a balanced dataset. The National
                       Health and Nutrition Survey is a government-designated, statistics-driven study based
                       on Article 17 of the Statistics Act (approval no. 117002). In the 5th round, the 1st year
                       survey is 2010-02CON-21-C, the 2nd year survey is 2013-12EXP-03-5C, and the 3rd year
                       survey is 2012-01EXP-01-2C. In the 6th round, the 1st year survey is 2013-07CON-03-4C,
                       and the second year survey is 2013-12EXP-03-5C. In the 3rd year, the survey was conducted
                       without deliberation by the Research Ethics Review Committee, as it corresponds to the
                       research conducted by the State for public welfare directly pursuant to Subparagraph 1 of
                       Article 2 (2).
conducted by the State for public welfare directly pursuant to Subparagraph 1 of A
                       2 (2).
Water 2021, 13, 2716                                                                                                3 of 10

                       2.2. Study Population
                             The sampling was performed using a two-stage, stratified, cluster extraction m
                         2.2. Study Population
                       with probability proportionality. Of the total 64,758, 48,422 people were selected, ex
                              The sampling was performed using a two-stage, stratified, cluster extraction method
                       ing  those who were taking medication, those with systemic diseases, and smoker
                         with probability proportionality. Of the total 64,758, 48,422 people were selected, excluding
                       pending
                         those who onwere
                                      the taking
                                           intakemedication,
                                                   of water,those
                                                                134 with
                                                                     people   in the
                                                                          systemic     ‘7 cups’
                       were classified. There were no other ingredients added to the water, and the standa  group  were
                         classified. There were no other ingredients added to the water, and the standard for 1 cup
                       1 cup  is 200 mL (See Figure 1).
                         is 200 mL (See Figure 1).

                         Figure 1. The flow of sample selection in this study.
                       Figure 1. The flow of sample selection in this study.
                         2.3. Variables
                         2.3.1.
                       2.3.     Dependent Variables
                            Variables
                              We identified demographic characteristics, oral health behaviors, and oral health
                       2.3.1. Dependent    Variables
                          status as key dependent variables. Demographic characteristics considered were survey
                         year,We   identified
                                gender,          demographic
                                         age, marital              characteristics,
                                                       status, education,  economy, andoralincome,
                                                                                             health confirmed
                                                                                                      behaviors,     andthe
                                                                                                                  using    oral heal
                       tushealth  survey
                             as key      from the National
                                       dependent              Health Demographic
                                                       variables.    and Nutrition Survey.    Economy wasconsidered
                                                                                        characteristics      classified into were s
                         ‘currently
                       year,         employed’
                               gender,            or ‘unemployed’,
                                          age, marital               and income was
                                                           status, education,          classifiedand
                                                                                   economy,       into income,
                                                                                                       ‘low’, ‘middle-low’,
                                                                                                                   confirmed usin
                         ‘middle’, ’middle-high’, and ‘high’. In the oral health behavior section, toothbrushing
                       health    survey from
                          time consisted           the and
                                           of 9 items,  National
                                                            the useHealth     and Nutrition
                                                                     of oral health               Survey.
                                                                                    products consisted    of Economy
                                                                                                              5 items, with was clas
                       into  ‘currently
                         1 for  yes and 0 employed’       or ‘unemployed’,
                                           for no. The dental                    and income
                                                                 treatment consisted             was
                                                                                       of 9 items,     classified
                                                                                                    with  1 for the into   ‘low’, ‘m
                                                                                                                     case of
                       low’,   ‘middle’,
                          receiving         ’middle-high’,
                                     treatment                 andof‘high’.
                                                 and 0 for the case            In the treatment.
                                                                       not receiving   oral health    behavior
                                                                                                   To consider     section,
                                                                                                                 oral  health toothb
                       ing time consisted of 9 items, and the use of oral health products consistedyes
                          status, chewing   inconvenience    and  experience  in toothache  were   checked,  with  1  for of 5 items
                       1 for yes and 0 for no. The dental treatment consisted of 9 items, with 1 for the c
                       receiving treatment and 0 for the case of not receiving treatment. To consider oral
                       status, chewing inconvenience and experience in toothache were checked, with 1 f
Water 2021, 13, 2716                                                                                         4 of 10

                       and 0 for no. Speech problems and chewing problems were measured on a 5-point scale;
                       the higher the score, the less serious the problem. Self-oral health consciousness was also
                       measured on a 5-point scale on which the lower the score, the better. Dental caries and
                       periodontal disease were directly examined by a public health dentist in the province at a
                       mobile examination center. A subject was recorded as having periodontal disease if their
                       periodontal pocket was more than 3 mm deep using a probe. Permanent tooth caries and
                       experience of permanent tooth caries were recorded by checking tooth caries using explorer.
                       The presence of the disease was marked as 1, and the absence of the disease was marked
                       as 0.

                       2.3.2. Independent Variables
                            We divided the population into three categories to determine their water intake. In
                       the KNHNS, respondents were asked the question, ‘How much water (mineral water) do
                       you drink per day?’ The unit was measured as ‘cup (200 mL)’, and it was divided into
                       4 groups as ‘7 cups’ according to water intake.

                       2.4. Statistical Analyses
                             Data analysis was conducted using IBM SPSS ver. 21.0 (IBM Co., Armonk, NY, USA),
                       and complex sampling analysis with stratification variables, colony variables, and weights
                       assigned was applied to all analyses. The comparison of demographic characteristics and
                       oral health behaviors according to 134 people in the ‘7 cups’
                       group was conducted using a complex sample chi-squared test. Logistic regression analysis
                       and linear regression analysis were performed in order to determine the effect of daily
                       water intake on oral health, and ‘Don’t Know’, ‘Not Applicable’, and ‘Missing Values’ in 8,
                       9, 88, and 99 were all excluded. Factors affecting the results of regression analysis were
                       identified and analyzed with three models (Model 1: crude model; Model 2: adjusted for
                       age and gender; Model 3: adjusted for oral health behavior). The number of subjects in
                       all tables was presented with an unweighted frequency, and the significance level of the
                       statistical test was set to 0.05.

                       3. Results
                       3.1. Demographic Characteristics According to Daily Water Intake
                             The ratio of the ‘7 cups’ group was highest in 2010 (Figure 2). In the ‘7 cups’ group, the ratio of ‘21–40 years old’ was higher, and in the ‘1–4 cups’ group
                       and ‘5–7 cups’ group, the ratio of ‘41–60 years old’ was higher. In the ‘7 cups’ group, the ratio of men was higher than that of women.
                       As for marital status, the ratio of married people was higher in all groups. In the ‘7 cups’ group, middle-low income was highest. In the ‘1–4 cups’ group,
                       low income was highest, and in the ‘5–7 cups’ group, middle income was highest. As for
                       education, in the ‘7 cups’ groups,
                       high school graduate was highest. In terms of economic activities, employed was higher
                       than currently unemployed regardless of the group. There were significant differences in
                       all items of demographic characteristics (Table 1) (p < 0.05).
OR PEER REVIEW                                                                                                                           5 of 10
      Water 2021, 13, 2716                                                                                                                       5 of 10

                                                Figure 2. Percentage of daily water intake by year (%).
                 Figure 2. Percentage of daily water intake by year (%).
                                      Table 1. Demographic characteristics according to daily water intake N (%).
          Table 1. Demographic characteristics according to daily water intake N (%).
                                                              7 Cups
                                                                                                                                                p
                                                             (N = 134)          (N = 27,223)         (N = 14,693)        (N = 6372)
                         7 Cups
               Age                 ≤20                    21 (15.7)            7879 (26.1)            2772 (17.0)    1037 (14.7) p             0.000
                             134) 21–40              27,223)
                                                          34 (38.2)
                                                                               14,693)
                                                                               5048 (26.2)
                                                                                                          (N = 6372) 1869 (38.7)
                                                                                                      3300 (31.1)
      ≤20                    21 (15.7)41–60                35 (27.0)
                                                     7879 (26.1)                6758(17.0)
                                                                              2772   (28.8)           46541037
                                                                                                           (35.1) (14.7) 2159 (35.1) 0.000
                                         ≥61                 44 (19.1)           7538 (18.8)          3769 (16.8)        1307 (11.5)
     21–40 Gender            34 (38.2)Male           5048 (26.2)
                                                           57 (46.0)          3300
                                                                               10,189(31.1)
                                                                                      (42.0)          69351869
                                                                                                           (54.6) (38.7) 3746 (66.2)           0.000
                                       Female                77 (54.0)          17,034 (58.0)         7758 (45.4)        2626 (33.8)
     41–60                   35 (27.0)               6758 (28.8)              4654 (35.1)                  2159 (35.1)
             Married                   Single                42 (42.7)          9910 (39.3)           4149 (32.6)        1929 (36.3)           0.000
      ≥61                    44   (19.1)
                                      Married        7538   (18.8)
                                                             92 (57.3)        3769
                                                                               17,271(16.8)
                                                                                      (60.7)         10,5311307
                                                                                                            (67.4)(11.5) 4435 (63.7)

      Male    Income         57 (46.0)Low                   23 (20.4)
                                                    10,189 (42.0)               5424(54.6)
                                                                              6935   (21.2)           27373746
                                                                                                           (19.9) (66.2) 1263 (20.5) 0.000 0.031
                                     Middle-low             34 (25.7)           5567 (20.7)           2867 (20.0)        1271 (20.7)
     Female                  77   (54.0)
                                       Middle       17,034 (58.0)
                                                            25 (17.5)         7758
                                                                                5358(45.4)
                                                                                     (19.7)           30272626
                                                                                                           (20.5) (33.8) 1249 (19.3)
                                    Middle-high             27 (18.5)           5484 (19.8)           2939 (19.6)        1254 (19.6)
     Single                  42   (42.7)High         9910 (39.3)
                                                            22 (17.9)         4149
                                                                                5170(32.6)
                                                                                     (18.7)           30241929
                                                                                                           (20.1) (36.3) 1296 (19,9) 0.000
    Married
          Education          92 (57.3)         17,271 (60.7)
                                Elementary school      37 (19.9)             10,531
                                                                               12,089 (67.4)
                                                                                      (35.8)          47004435
                                                                                                           (24.0) (63.7) 1485 (16.7)       0.000
                                    Middle school            17 (15.0)          2666 (11.1)           1670 (12.0)         807 (12.5)
      Low                    23   (20.4)
                                     High school     5424   (21.2)
                                                             25 (25.6)        2737
                                                                                5554(19.9)
                                                                                     (26.5)           39281263
                                                                                                           (34.0) (20.5) 2017 (37.8) 0.031
                                     University              43 (39.5)          5612 (26.6)           3725 (31.2)        1775 (33.1)
  Middle-low                 34 (25.7)               5567 (20.7)              2867 (20.0)                  1271 (20.7)
        Economic activity            Employed                65 (61.2)         10,041 (55.2)          6818 (62.0)        3468 (67.0)           0.000
     Middle                  25   (17.5)
                                    Unemployed       5358   (19.7)
                                                             47 (38.8)        3027
                                                                                9475(20.5)
                                                                                     (44.8)           51491249
                                                                                                           (38.0) (19.3) 1999 (33.0)
                                                      Note: By complex sample chi-square test, p < 0.05.
  Middle-high                27 (18.5)               5484 (19.8)              2939 (19.6)                  1254 (19.6)
      High                   22 (17.9) 3.2. Oral5170  (18.7)
                                                 Health               3024to(20.1)
                                                        Behavior According                   1296 (19,9)
                                                                             Daily Water Intake

   Elementary                                   In terms of toothbrushing, brushing before dinner and before going to bed was highest
                             37 (19.9) in the ‘7 cups’ group. There were significant differences
                             17 (15.0) in all items.
                                                2666As(11.1)
                                                        for the use of1670  (12.0) products, the
                                                                       oral health             807use
                                                                                                   (12.5)
                                                                                                      of electric toothbrushes was
     school
                                       highest in the ‘
Water 2021, 13, 2716                                                                                                                       6 of 10

                                     ‘>7 cups’ group; there were significant differences in all items except for the use of oral
                                     health products. In dental treatment, simple caries treatment and prosthetic treatment
                                     were highest in the ‘7 cups’ group. There were
                                     significant differences in all items except went to the dentist, oral examination, simple
                                     caries treatment, trauma treatment, and prosthetic treatment (Table 2) (p < 0.05).

                                    Table 2. Oral health behavior according to daily water intake N (%).

                                                                               7 Cups       p
                             I brushed my teeth yesterday. (N = 45,858)       119 (98.2)     25,635 (98.0)   14,010 (98.9)   6094 (99.0)   0.000
                        I brushed my teeth before breakfast. (N = 12,762)      35 (31.2)      6698 (29.2)     4057 (31.3)    1972 (35.0)   0.000
                         I brushed my teeth after breakfast. (N = 31,825)      74 (61.2)     17,637 (65.9)    9936 (68.0)    4178 (65.1)   0.037
                             I brushed my teeth before lunch. (N = 589)         2 (1.3)        286 (1.2)       196 (1.3)      105 (1.8)    0.002
   Toothbrushing            I brushed my teeth after lunch. (N = 20,774)      54 (46.3)      11,373 (45.1)    6517 (47.4)    2830 (47.3)   0.000
                           I brushed my teeth before dinner. (N = 1012)         4 (3.6)        490 (2.1)       323 (2.4)      195 (3.3)    0.000
                           I brushed my teeth after dinner. (N = 27,191)      59 (49.5)      14,533 (56.0)    8771 (61.9)    3828 (61.8)   0.000
                            I brushed my teeth after a snack. (N = 1252)        1 (0.8)        624 (2.5)       424 (3.0)      203 (3.2)    0.002
                       I brushed my teeth before going to bed. (N = 18,974)   52 (45.0)      10,696 (44.2)    5596 (42.4)    2630 (45.7)   0.000
                             Use of oral health products (N = 2659)             7 (18.7)      1292 (22.8)     911 (25.3)      449 (23.8)   0.131
                                     Use of floss (N = 7013)                   16 (24.0)      3536 (21.6)    2344 (23.7)     1117 (25.1)   0.000
     Oral health
                              Use of interdental brush (N = 6230)               8 (6.9)       3095 (18.1)    2098 (20.3)     1029 (22.3)   0.000
      products
                                 Use of mouthwash (N = 6184)                   11 (12.6)      3008 (17.9)    2182 (21.4)      983 (20.9)   0.000
                             Use of electric toothbrush (N = 1758)              9 (10.8)       862 (5.2)      576 (5.8)        311 (6.8)   0.000
                                 I went to the dentist. (N = 19,279)           44 (39.8)     10,685 (40.9)   6027 (42.3)     2523 (40.6)   0.092
                             I had an oral examination. (N = 14,173)           27 (65.2)      7852 (73.3)    4449 (74.3)     1845 (73.5)   0.374
                             I had periodontal treatment. (N = 3403)             5 (8.5)      1693 (15.7)    1196 (19.5)     509 (18.9)    0.000
       Dental
                            I had simple caries treatment. (N = 5892)          13 (36.7)      3345 (31.6)    1784 (30.9)      750 (29.8)   0.383
     Treatment
                                  I had pulp treatment. (N = 3348)              5 (15.2)      1763 (16.8)    1091 (19.1)     489 (19.2)    0.010
   (within the last
                                 I had oral health care. (N = 7225)            12 (33.2)      3760 (37.5)    2401 (42.3)     1052 (43.8)   0.000
        year)
                               I had surgical treatment. (N = 2343)             5 (16.9)      1201 (11.7)     776 (13.1)      361 (14.9)   0.000
                                I had trauma treatment. (N = 416)               1 (2.7)        226 (2.3)       119 (2.2)       70 (2.8)    0.364
                              I had prosthetic treatment. (N = 3972)           12 (20.2)      2158 (18.3)    1284 (19.6)      518 (18.3)   0.250
                                                 Note: By complex sample chi-square test, p < 0.05.

                                     3.3. Oral Health Status According to Daily Water Intake
                                          Chewing inconvenience was highest in the ‘1–4 cups’ group, and the experience in
                                     toothache was highest in the ‘7 cups’ group, and self-oral health consciousness was worst
                                     in the ‘
Water 2021, 13, 2716                                                                                                                             7 of 10

                                       Table 3. Oral health status according to daily water intake N(%).

                                                                           7 Cups             p
                         Chewing inconvenience (N = 9222)                 22 (21.2)         5148 (22.8)       2833 (20.8)       1219 (19.8)      0.000
                        Experience in toothache (N = 10,197)              37 (35.1)         5551 (30.4)       3180 (32.7)       1429 (32.7)      0.008
   Oral health                    † Speech problem                       4.26 ± 0.01        4.33 ± 0.01       4.40 ± 0.01       4.45 ± 0.01      0.000
     status                      † Chewing problem                       3.74 ± 0.13        3.70 ± 0.01       3.78 ± 0.01       3.85 ± 0.02      0.000
                          † Self-oral health consciousness               3.34 ± 0.10        3.28 ± 0.01       3.29 ± 0.01       3.33 ± 0.02      0.032
  −
  \   Oral disease        Prevalence of periodontal disease             Permanent caries prevalence            Permanent caries experience
                            OR (95% CI)                p                OR (95% CI)          p               OR (95% CI)           p
                                                                           1.032                                 1.075
      Model 1            1.018 (1.006~1.029)             0.002                                 0.000                                   0.000
                                                                       (1.023~1.041)                         (1.062~1.089)
                                                                           1.022                                 1.060
      Model 2            1.018 (1.006~1.029)             0.003                                 0.000                                   0.000
                                                                       (1.013~1.032)                         (1.046~1.073)
                                                                           1.001                                 0.952
      Model 3            1.097 (1.017~1.184)             0.017                                 0.947                                   0.032
                                                                       (0.970~1.033)                         (0.911~0.996)
       Note: By complex sample chi-square test, † by complex sample linear regression analysis, −\ by complex sample logistic regression analysis,
       Model 1: crude model, Model 2: adjusted for age and gender, Model 3: adjusted for oral health behavior.

                                      4. Discussion
                                            As interest in immunity increases following the COVID-19 pandemic, interest in the
                                      effect of water intake on immune function and systemic diseases is growing [26]. Recently,
                                      it has been suggested that mild dehydration can lead to changes in various cognitive
                                      functions, such as concentration, arousal, and short-term memory [27]. On the other
                                      hand, Benton [28] argued that there are very few studies on the effect of dehydration
                                      on cognitive function, and confounding factors such as fatigue and body temperature
                                      related to dehydration are not well controlled, thereby making it difficult to draw a definite
                                      conclusion. While studies on water, systemic diseases, and mental disorders continue,
                                      studies confirming the relationship between water and oral disease are mostly those related
                                      to bacteria [25] and those limited to the elderly [18,25]. For this reason, it is necessary to
                                      expand these studies; as such, this study expanded and investigated subjects by using the
                                      data from the National Health and Nutrition Survey representing Korea and analyzed the
                                      relationship between water and oral disease through the data from 2010 to 2017.
                                            Women’s water intake was lower than that of men, which is the same result reported
                                      in studies conducted in the US and Canada [29–31] and is theorized to be a complex result
                                      influenced by female hormones [32]. Differences in water intake according to gender are
                                      an area requiring further research. In addition, it is necessary to consider socioeconomic
                                      aspects to increase water intake, as the water intake was lower in high-income, education,
                                      and unemployed states.
                                            In regard to toothbrushing among the oral health behaviors, water intake was high
                                      in all groups except for before dinner and before going to bed and was also high in all
                                      groups using oral health products except for the use of electric toothbrushes in which
                                      water intake was high. This indicates that oral health behavior is good in the group that
                                      consumes more water per day, which is consistent with the study of Nam et al. [19] that
                                      water intake behavior and oral care behavior are related. However, there is no relationship
                                      between tongue brushing, the number of brushings, brushing time, and the use of auxiliary
                                      oral hygiene products among oral health behaviors; as a result, further research is deemed
                                      necessary. In addition, it was found that the group with high water intake received
                                      relatively simple treatments and preventive treatments, and the group with low water
                                      intake received more serious treatments. It is theorized that people receive more treatment
                                      to maintain and promote oral health due to a higher degree of interest in health, including
                                      water intake.
                                            In the oral health status section, the group who consumed less water per day experi-
                                      enced a high incidence of toothache and perceived that they had bad oral health status. In
                                      addition, the group with high water intake had no speech problems, chewing problems,
Water 2021, 13, 2716                                                                                               8 of 10

                       or chewing inconvenience. As such, it was confirmed that oral health and water intake
                       are highly related, as oral health problems were low in the group who consumed more
                       water per day. In fact, the prevalence of periodontal disease increased by 1.018 times, the
                       prevalence of dental caries increased by 1.032 times, and the experience of dental caries
                       increased by 1.075 times each time a person drank one less cup of water per day. Although
                       this was analyzed by adjusting for age, gender, and oral health behavior affecting water
                       intake and oral disease, the result was found to be significant, thereby confirming the
                       importance of water intake for oral disease.
                             Since dental caries and periodontal disease are multifactorial diseases in which several
                       factors act in combination, water intake cannot be limited as the cause of increasing or
                       decreasing the likelihood of oral disease. In addition, periodontal disease was diagnosed
                       when the depth of the periodontal pocket was 3 mm or more in the examination for
                       the prevalence of periodontal disease investigated in the National Health and Nutrition
                       Examination Survey. This can lead to overdiagnosis if the depth of the periodontal pocket
                       is 3 mm in the case of prosthetic teeth or implants that are not natural teeth. Nevertheless, it
                       has been confirmed that water intake is highly related to oral diseases, and so it is thought
                       that a recommended intake of water should be included in dietary guidelines to prevent
                       oral diseases considering the importance of water intake. A limitation of this study is
                       that only associations, not causal relationships, can be drawn from the results owing to
                       its cross-sectional design, where investigations are restricted to a certain point within a
                       short window of time. Another limitation is that there are very few previous studies on
                       water intake and oral health behaviors and state for all age groups, so it was somewhat
                       difficult to compare and interpret the results of this study. A final limitation was that we
                       did not consider other sources of hydration (e.g., from other drinks and liquid foods, as
                       well as environmental (micro)/climatic conditions and lifestyles related to hydration, such
                       as humidity and temperature, physical activity, sport, drugs, water fluoridation area, eating
                       habits, etc.) that could influence the results of this study. Therefore, additional research
                       considering the various water sources of the subject is required. Despite these limitations,
                       it is meaningful that this study was analyzed through representative data of the National
                       Health and Nutrition Examination Survey to motivate Koreans regarding water intake.
                       Moreover, this study is significant in providing data that can be used for direction setting
                       when establishing policies or business plans for the recommendation of water intake at the
                       national level. The relationship between water intake and oral health requires further and
                       continuous research, and follow-up studies to establish standards of proper water intake in
                       order to lower oral disease are necessary.

                       5. Conclusions
                            Based on the above results, people who consumed more water were at lower risk of
                       dental caries and periodontal disease. Additionally, people who consumed more water
                       were at lower risk of poor oral health status. Therefore, it is concluded that the govern-
                       ment’s active promotion of water intake recommendations and policies should be prepared
                       to include water intake as important in support of improved oral health.

                       Funding: This research received no specific grant from funding agencies in the public, commercial,
                       or not-for-profit sectors.
                       Institutional Review Board Statement: The study was conducted according to the guidelines of the
                       Declaration of Helsinki, and approved by the Institutional Review Board (In the 5th round, the 1st
                       year survey is 2010-02CON-21-C, the 2nd year survey is 2013-12EXP-03-5C, and the 3rd year survey
                       is 2012-01EXP-01-2C. In the 6th round, the 1st year survey is 2013-07CON-03-4C, and the 2nd year
                       survey is 2013-12EXP-03-5C. In the 3rd year, the survey was conducted without deliberation by the
                       Research Ethics Review Committee, as it corresponds to the research conducted by the State for
                       public welfare directly pursuant to Subparagraph 1 of Article 2 (2).).
                       Informed Consent Statement: Informed consent was obtained from all subjects involved in the study.
                       Acknowledgments: This study used the KNHANES data.
Water 2021, 13, 2716                                                                                                                  9 of 10

                                   Conflicts of Interest: The authors declare no conflict of interest.

References
1.    Jéquier, E.; Constant, F. Water as an essential nutrient: The physiological basis of hydration. Eur. J. Clin. Nutr. 2010, 64, 115–123.
      [CrossRef]
2.    Perrier, E.; Vergne, S.; Klein, A.; Poupin, M.; Rondeau, P.; Le Bellego, L.; Armstrong, L.E.; Lang, F.; Stookey, J.; Tack, I. Hydration
      biomarkers in free-living adults with different levels of habitual fluid consumption. Br. J. Nutr. 2013, 109, 1678–1687. [CrossRef]
3.    Lee, J.S. The effects of gender, obesity rate, nutrition knowledge and dietary attitude on the dietary self-efficacy on adolescents.
      Korean J. Community Nutr. 2003, 8, 652–657.
4.    Swallow, J.A. Quantitative study of enamel dissolution under conditions of controlled hydrodynamics. J. Dent. Res.
      1997, 56, 524–530. [CrossRef]
5.    Verbalis, J.G. Disorders of body water homeostasis. Best Pract. Res. Clin. Endocrinol. Metab. 2003, 17, 471–503. [CrossRef]
6.    EFSA Panel on Dietetic Products, Nutrition, Allergies. Scientific opinion on dietary reference values for water. EFSA J.
      2010, 8, 1459.
7.    Hillyer, M.; Menon, K.; Singh, R. The effects of dehydration on skill-based performance. Int. J. Sports Sci. 2015, 5, 99–107.
      [CrossRef]
8.    Daniels, M.C.; Popkin, B.M. Impact of water intake on energy intake and weight status: A systematic review. Nutr. Rev.
      2010, 68, 505–521. [CrossRef] [PubMed]
9.    Ruth, J.L.; Wassner, S.J. Body composition: Salt and water. Pediatr. Rev. 2006, 27, 181–187. [CrossRef]
10.   Committee on Nutrition and the Council on Sports Medicine and Fitness. Sports drinks and energy drinks for children and
      adolescents: Are they appropriate? Pediatrics. 2011, 127, 1182–1189. [CrossRef] [PubMed]
11.   Sawka, M.N.; Latzka, W.A.; Matott, R.P.; Montain, S.J. Hydration effects on temperature regulation. Int. J. Sports Med.
      1998, 19, S108–S110. [CrossRef] [PubMed]
12.   Sawka, M.N.; Cheuvront, S.N.; Carter, R. Human water needs. Nutr. Rev. 2005, 63, S30–S39. [CrossRef] [PubMed]
13.   Raman, A.; Schoeller, D.A.; Subar, A.F.; Troiano, R.; Schatzkin, A.; Harris, T.; Bauer, D.; Bingham, S.A.; Everhart, J.E.; Newman,
      A.B.; et al. Water turnover in 458 American adults 40–79 yr of age. Am. J. Physiol. Renal Physiol. 2004, 286, F394–F401. [CrossRef]
      [PubMed]
14.   Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate (the
      US/Canada); Panel on Dietary Reference Intakes for Electrolytes and Water; The National Academies Press: Washington DC, USA,
      2005; pp. 1–616. [CrossRef]
15.   Chidester, J.; Spangler, A. Fluid intake in the institutionalized elderly. J. Am. Diet Assoc. 1997, 97, 23–28. [CrossRef]
16.   Feddes, J.J.; Emmanuel, E.J.; Zuidhoft, M.J. Broiler performance, body weight variance, feed and water intake, and carcass quality
      at different stocking densities. Poultry Sci. 2002, 81, 774–779. [CrossRef]
17.   Pêgo, C.; Guelinckx, I.; A Moreno, L.; Kavouras, S.; Gandy, J.J.; Martinez, H.; Bardosono, S.; Abdollahi, M.; Nasseri, E.;
      Jarosz, A.; et al. Total fluid intake and its determinants: Cross-sectional surveys among adults in 13 countries worldwide. Eur. J.
      Nutr. 2015, 54, 35–43. [CrossRef]
18.   Armstrong-Esther, C.; Browne, K.; Armstrong-Esther, D.; Sander, L. The institutionalized elderly: Dry to the bone! Int. J. Nurs.
      Stud. 1996, 33, 619–628. [CrossRef]
19.   Nam, J.Y.; Kim, H.J.; Park, S.M.; Choi, S.H.; Jeon, H.I.; Kim, M.J.; Lee, M.K. The influence of water drinking on oral management
      behavior and bad breath in college students. AJMAHS 2017, 7, 421–429. [CrossRef]
20.   Hong, M.H. Study on detection of oral bacteria in the saliva and risk factors of adults. JKAIS 2014, 15, 5675–5682. [CrossRef]
21.   Kang, K.H.; Kim, Y.K.; Lee, H.S.; Jin, I. Analysis of gene expression in response to acid stress of streptococcus mutans Isolated
      from a Korean child. JKAIS 2009, 10, 2990–2996. [CrossRef]
22.   Sofia, D.F.; Marika, B.; Arthur, C.O. Streptococcus mutans, caries and simulation models. Nutriens 2010, 2, 290–298. [CrossRef]
23.   Park, S.N.; Kook, J.K. Development of quantitative real-time PCR primers for detection of development prevotella intermedia.
      Int. J. Oral Biol. 2015, 40, 205–210. [CrossRef]
24.   Peck, S.Y.; Ku, Y.; Rhyu, I.C.; Hahm, B.D.; Han, S.B.; Choi, S.M.; Chung, C.P. The frequency of detecting prevotella intermedia and
      prevotella nigrescens in Korean adult periodontitis patients. J. Periodontal Implant Sci. 2000, 30, 419–429. [CrossRef]
25.   Joung, H.Y.; Choi, Y.; Choe, H.J.; Jung, I.H. A Convergence study of Water intake on relationship between Xerostomia, Halitosis,
      Oral microorganisms in the Elderly. J. Korea Converg. Soc. 2019, 10, 309–316. [CrossRef]
26.   Paik, I.Y.; Yun, D.S.; Suh, S.H.; Roh, H.T. Effects of Different Fluid Replacements during Exercise in High Ambient Temperature
      on Inflammatory Cytokine Responses and Immune Function in Elite Athletes. KJSS 2011, 22, 2076–2087. [CrossRef]
27.   Popkin, B.M.; D’Anci, K.E.; Rosenberg, I.H. Water, hydration, and health. Nutr. Rev. 2010, 68, 439–458. [CrossRef]
28.   Benton, D. Dehydration influences mood and cognition: A plausible hypothesis? Nutrients 2011, 3, 555–573. [CrossRef] [PubMed]
29.   Kant, A.K.; Graubard, B.I.; Atchison, E.A. Intakes of plain water, moisture in foods and beverages, and total water in the adult
      US population—Nutritional, meal pattern, and body weight correlates: National Health and Nutrition Examination Surveys
      1999–2006. Am. J. Clin. Nutr. 2009, 90, 655–663. [CrossRef] [PubMed]
30.   Park, S.; Sherry, B.; O’Toole, T.; Huang, Y. Factors associated with low drinking water intake among adolescents: The Florida
      Youth Physical Activity and Nutrition Survey, 2007. J. Am. Diet Assoc. 2011, 111, 1211–1217. [CrossRef] [PubMed]
Water 2021, 13, 2716                                                                                                           10 of 10

31.   Pintar, K.D.M.; Waltner-Toews, D.; Charron, D.; Pollari, F.; Fazil, A.; McEwen, S.A.; Nesbitt, A.; Majowicz, S. Water consumption
      habits of a south-western Ontario community. J. Water Health 2009, 7, 276–292. [CrossRef] [PubMed]
32.   Stachenfeld, N.S. Hormonal changes during menopause and the impact on fluid regulation. Reprod. Sci. 2014, 21, 555–561.
      [CrossRef] [PubMed]
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