Association between the Frequency of Daily Toothbrushing and Development of Nonalcoholic Fatty Liver Disease

Abstract

Background & Aims: This study aimed to evaluate the association between the frequency of daily tooth brushing and the development of nonalcoholic fatty liver disease (NAFLD). Methods: A retrospective longitudinal study was conducted from 2005 to 2012 at the Center for Preventive Medicine at St. Luke's International Hospital, Japan. Data on all participants who underwent a health checkup during the study period were collected. NAFLD was diagnosed by abdominal ultrasonography, and all participants who were diagnosed with NALFD at the time of their initial visit, consumed alcohol in any amount, or had received only one health checkup were excluded. The questionnaire for the frequency of daily tooth brushing was conducted as part of health checkups. The primary outcome was the risk of developing NAFLD according to the frequency of daily tooth brushing (1-2 times a day, or 3 times a day) compared to those who brush teeth once or less than once a day. Results: Data were collected from 25,804 people. A total of 3,289 (12.7%) participants developed NAFLD. The mean age was 45.2 years, and 6,901 (26.7%) of the participants were male. The risk of developing NAFLD significantly decreased with increased frequency of daily tooth brushing. Adjusted odds ratios (ORs) are as follows: Brushing teeth 1-2 times a day (OR: 0.85, 95% CI: 0.77-0.95), and 3 times a day (OR: 0.74, 95% CI: 0.67-0.82). Conclusions: Frequent tooth brushing was shown to significantly reduce the risk of developing NAFLD.

Association between oral health behavior and chronic diseases among middle-aged and older adults in Beijing, China

“…Possible reasons for the inconsistency between the results of these studies and the current study are differences in study design, population, measurement and classification of diseases. A few studies have found that a lower frequency of tooth brushing is related to a higher prevalence of liver diseases such as non-alcoholic fatty liver disease [ 25 ] or cirrhosis [ 46 ]. For example, a retrospective and single hospital-based study from Japan (mean age 44) showed that the risk of non-alcoholic fatty liver disease decreased significantly with increasing frequency of brushing teeth, with an OR of 1–2 times daily of 0.85 (95% CI: 0.77–0.95) and 3 times daily of 0.74 (95% CI: 0.67–0.82) compared with those who brush their teeth less than once a day [ 25 ].…”

“…A few studies have found that a lower frequency of tooth brushing is related to a higher prevalence of liver diseases such as non-alcoholic fatty liver disease [ 25 ] or cirrhosis [ 46 ]. For example, a retrospective and single hospital-based study from Japan (mean age 44) showed that the risk of non-alcoholic fatty liver disease decreased significantly with increasing frequency of brushing teeth, with an OR of 1–2 times daily of 0.85 (95% CI: 0.77–0.95) and 3 times daily of 0.74 (95% CI: 0.67–0.82) compared with those who brush their teeth less than once a day [ 25 ]. However, this is a single hospital-based study, evaluation by multicenter studies and meta-analyses by different ethnic groups should be considered.…”

“…However, another study found no association between the frequency of brushing and diabetes [ 16 ]. Additionally, a small number of other studies have discovered a link between poor oral health behavior and an increased risk of liver diseases [ 16 , 25 ] and upper aerodigestive tract cancer risk [ 26 ]. Nevertheless, the existing studies have shown that the strength of the association between oral health practices and chronic conditions may vary across ethnic or geographic populations [ 19 , 27 ], and a few studies have suggested the degree of the association between brushing practices and various chronic diseases, including musculoskeletal, digestive, respiratory, and genitourinary diseases [ 25 , 28 ].…”

Association between oral health behavior and multiple chronic diseases among middle-aged and older adults in Beijing, China

“…A few studies found that lower frequency of teeth brushing is related to higher prevalence of liver diseases, non-alcoholic fatty liver disease 17 or cirrhosis 28 . However, we did not observe associations between toothbrushing and risk of diseases of upper or lower respiratory, and liver or gallbladder.…”

“…Two cohort studies showed an association between poor oral hygiene and higher risk of diabetes 14,15 , whereas another study found no association between them 13 . In addition, oral health behavior has been associated with upper aerodigestive tract cancer risk 16 , liver diseases 13,17 . Nevertheless, the existing studies on the association between oral hygiene behavior and the risk of multiple chronic diseases have not measured the frequency of brushing accurately, and the studies on multi-system diseases and speci c regions in China are very limited.…”