Open AccessResearch

Dental status and incident falls amongolder Japanese: a prospective cohort
study
Tatsuo Yamamoto,1 Katsunori Kondo,2 Jimpei Misawa,2 Hiroshi Hirai,3
Miyo Nakade,4 Jun Aida,5 Naoki Kondo,6 Ichiro Kawachi,7 Yukio Hirata1

To cite: Yamamoto T,
Kondo K, Misawa J, et al.
Dental status and incident
falls among older Japanese:a prospective cohort study.
BMJ Open 2012;2:e001262.
doi:10.1136/
bmjopen-2012-001262< Prepublication history forthis paper is available online.
To view this file please visit
the journal online(http://dx.doi.org/10.1136/
bmjopen-2012-001262).
Received 4 April 2012
Accepted 5 July 2012
This final article is available
for use under the terms of
the Creative Commons
Attribution Non-Commercial
2.0 Licence; see
http://bmjopen.bmj.com

For numbered affiliations see
end of article.
Correspondence to
Dr Yukio Hirata;
hiratay@kdcnet.ac.jp

ABSTRACT
Objective: To examine if self-reported number ofteeth, denture use and chewing ability are associatedwith incident falls.
Design: Longitudinal cohort study (the Aichi
Gerontological Evaluation Study).
Setting: 5 Japanese municipalities.
Participants: 1763 community-dwelling individuals
aged 65 years and older without experience of falls
within the previous year at baseline.
Main outcome measures: Self-reported history ofmultiple falls during the past year at the follow-up
survey about 3 years later. Baseline data on thenumber of teeth present and/or denture use andchewing ability were collected using self-administeredquestionnaires. Logistic regression analyses controlled
for sex, age, functional disability during follow-up
period, depression, self-rated health and educational
attainment.
Results: 86 (4.9%) subjects reported falls at thefollow-up survey. Logistic regression models fully
adjusted for all covariates showed that subjects having
19 or fewer teeth but not using dentures hada significantly increased risk for incident falls (OR2.50, 95% CI 1.21 to 5.17, p¼0.013) compared withthose having 20 or more teeth. Among subjects with19 or fewer teeth, their risk of falls was not
significantly elevated so long as they wore dentures(OR 1.36, 95% CI 0.76 to 2.45, p¼0.299). No
significant association was observed between chewing
ability and incident falls in the fully adjusted model.
Conclusions: Having 19 or fewer teeth but not using
dentures was associated with higher risk for theincident falls in older Japanese even after adjustment
for multiple covariates. Dental care to prevent tooth
loss and denture treatment for older people might
prevent falls, although the authors cannot exclude thepossibility that the association is due to residual
confounding.

INTRODUCTION
Falls occur frequently in older people andadversely affect their quality of life. Morethan one-third of persons aged 60 years andolder fall each year in Japan,1 England2 andARTICLE SUMMARY
Article focus
An association has been reported between dental
occlusion and physical function including lower
extremity dynamic strength and balance.
- Whether number of teeth, denture use andchewing ability predict subsequent incidence offalls is unknown.
- The aim of this study was to examine if selfreported number of teeth, denture use andchewing ability are associated with incident falls.
-

Key messages
Having 19 or fewer teeth but not using dentures
was a strong independent predictor of incident
falls in a community-dwelling older population.
- In addition to preventing tooth loss, denture
treatment for older people might prevent falls.
-

Strengths and limitations of this study
Strengths of this study include large sample size,
population-based sampling and control for manypotential confounding factors.
- The following limitations should be considered:
the information on dental status and falls was
self-reported and misclassification of cases ispossible. Moreover, we cannot exclude thepossibility that the association is due to residual
confounding.
-

the USA,3 and in half of cases, falls arerecurrent.3 The consequences of falls aresevere: 6% of falls lead to a fracture and 24%
lead to other serious injuries.2 Thus, falls
impose a burden on the sustainability ofhealth and long-term care in Japan and manyother countries, where population is rapidly
ageing.4 In Japan, the annual health andlong-term care costs attributable to falls areabout 730 thousand million Japanese yen in
2002, which amounts to roughly 5% of theentire health and long-term care costs.5
A number of studies6 including those using
Japanese data7 have identified risk factors forfalls, including female sex, older age, having
a history of falls, arthritis, cerebrovascular

Yamamoto T, Kondo K, Misawa J, et al. BMJ Open 2012;2:e001262. doi:10.1136/bmjopen-2012-001262

1

Dental status and incident falls among older Japanesedisease, depression and the impairment of muscle
strength
and/orbalance.
Although
exerciseprogrammes including balance training are effective,8
multifactorial fall prevention programmes to addressthese risk factors have not been successful in reducing
falls.9 A recent systematic review concluded that there islimited evidence to suggest that multifactorial fall
prevention programmes in primary care, community or
emergency care settings are effective in reducing thenumber of falls.10 Therefore, identification of additional
modifiable risk factors may be helpful to establish more
effective programmes for fall prevention.
Unhealthy dental status is a candidate risk factor for
falls.11 12 A longitudinal study showed that partial orcomplete loss of dental occlusion was associated witha decline in lower extremity dynamic strength andbalance function.13 One 1-year prospective longitudinal
study using 146 demented older people reported theassociation between dental occlusion and subsequentphysical health.14 Researchers have argued that thesepotential links between dental health and physicalhealth may be because jaw position affects body
posture.11 Proprioceptive receptors of the masticatory
muscular system and dentoalveolar ligaments provide
sensory afferent input,15 and hence poor dental occlusion may decrease that proprioception, thereby interfering with the stability of head posture (and increasing
the risk of falling). However, whether or not dental
occlusion and chewing ability actually predict thesubsequent incidence of falls is largely unknown.
Therefore, this prospective study aimed to determine
the association between dental health in terms of thenumber of teeth present, denture use and chewing
ability and the incidence of falls in a large cohort ofolder Japanese people.
METHODS
Study population
Our analyses were based on data from the Aichi
Gerontological Evaluation Study (AGES) Project, an ongoing Japanese prospective cohort study.16 17 The
detailed protocol of the AGES and baseline characteristics of the study participants have been published elsewhere.16 18 In brief, the AGES aims to investigate thefactors related to the loss of healthy years, such asfunctional decline, cognitive impairment or deathamong non-institutionalised older people. The sample
was restricted to those who did not already have a physical or cognitive disability at baseline, defined by notreceiving public long-term care insurance benefits andself-reported dependence in walking, toileting andbathing.
The sampling frame for the AGES cohort was selected
as follows. In 2003, the residential registers of fivemunicipalities in Aichi prefecture were obtained withthe cooperation of city officials. From these comprehensive registers, we selected a random sample of one inthree citizens aged 65 years or older in four towns (1281,
2

1537, 1766 and 1873) and a random sample of 1666 ina city. They (N¼8123) were then mailed the baseline
questionnaire, inviting them to participate in the AGES
cohort study. Responses were obtained from 3998
subjects (49.2%), and 3981 subjects were identified
using ID. We mailed a follow-up survey between March
2006 and March 2007 to the 3471 subjects after
excluding 510 subjects who died or started receiving
insurance benefits due to certified disability (N¼472) or
could not be traced (N¼38). Two thousand six hundredand forty subjects responded to the follow-up survey(76.1%) and formed the analytic sample for our study.
After excluding 166 and 545 subjects who experienced
multiple and single falls, respectively, as well as 106
subjects without information of falls at baseline, we wereleft with 1823 subjects who did not report experiencing
falls at baseline. After excluding 56 subjects without
information on falls at follow-up and four subjects
without information on age, a total of 1763 subjects
formed the final analytic population of this study. The
AGES protocol was reviewed and approved by the Ethics
Committee on Research of Human Subjects at Nihon
Fukushi University.
Outcome variables
History of falls was ascertained by asking, “Have you had
any falls over the past year?” with possible answers of“multiple times,” “once” or “none.” Multiple falls wasused as an outcome and the last two categories werecombined because previous studies have found thatsingle fallers are more similar to non-fallers than torecurrent fallers on a range of medical, physical andpsychological risk factors.3 19 20
Dental health variables
Dental status and chewing ability were assessed using
a self-administered questionnaire. Respondents wereasked to classify their dental status as having 20 or moreteeth, having 19 or fewer teeth with dentures, having 19
or fewer teeth without dentures, having few teeth with
dentures or having few teeth without dentures. Data
from having 19 or fewer teeth with dentures and thosefrom having few teeth with dentures were combined.
Data from having 19 or fewer teeth without dentures andthose from having few teeth without dentures were also
combined.
Chewing ability was ascertained by asking, “How is yourability to chew?” with possible answers being “I can chew
anything I want,” “I can chew most foods with some
exceptions,” “I can eat limited foods as I cannot chew
very well,” “I can hardly chew anything” and “I haveliquid foods as I cannot chew at all.” Data from the last
three categories were combined due to the small
number of respondents.
Covariates
Studies suggest that falls are associated with sex,7 21 age,2 7
stroke,7 severe foot problems,2 impaired vision andimpaired hearing,2 activities of daily living (ADL),3 6 21

Yamamoto T, Kondo K, Misawa J, et al. BMJ Open 2012;2:e001262. doi:10.1136/bmjopen-2012-001262

Dental status and incident falls among older Japanesebody mass index (BMI),21 use of sedatives,2 depression,2 self-rated health,21 exercise,2 mobility2 andsocioeconomic status.22 Therefore, associations of incident fall with sex, age, present illness related to falls,
ADL, BMI, use of sedatives, depression, self-rated
health, exercise (how much they walked in minutes perday), frequency of outings, educational attainment andequivalised household income were analysed. Selfreported current medical treatment of stroke, osteoporosis, joint disease/neuralgia, injury/fracture,
impaired vision and/or impaired hearing was used asa variable for present illness related to falls. To evaluate
functional status, the survey asked whether the
respondents had difficulty or needed someone’s assistance in performing any of the following ADL: basing,walking and using the toilet.23 Subjects without difficulty for all three ADL items were categorised into ADL
without limitation and those with at least one ADL itemwith difficulty into ADL with limitation. BMI was categorised into three groups (<18.5, 18.5e24.9 and 25.0
or more).24 Depression was assessed with the shortversion of the Geriatric Depression Scale-15 developed
for self-administration in the community using a simple
yes/no format25 and was categorised into three groups:
0e4 (no), 5e9 (mild) and 10e15 (moderate to severe).
To adjust household income for household size,
equivalised income was calculated by dividing thehousehold income by the square root of the number ofhousehold members and grouped into one of the sevencategories. In addition to these covariates, data on
functional disability during follow-up period werecollected from the public long-term care insurance
database maintained by each participating municipality
and used as a covariate. Incidence of functional
disability was determined based on when a person
newly qualified for the insurance benefit, new registrations to the public long-term care insurance database.26
The distribution of each covariate at baseline for theoverall AGES 2003 cohort (n¼32 891) has beenreported elsewhere.16
Statistical analysis
Categorical variables that included missing data wererecorded by reassigning missing values to separate“missing” categories in order to maximise the number ofsubjects included in the statistical analysis and thereby
maximise statistical power. Logistic regression models
were used to calculate the ORs and 95% CIs for theincident falls at the follow-up. First, univariate ORs were
calculated for each dental health variable and eachcovariate. Variables that were marginally significant(p<0.10) in the univariate analyses were selected ascovariates for subsequent multivariate analysis. Then,logistic regression analysis was performed for eachdental variable after including sex, age, functional
disability during follow-up period, depression, self-rated
health and educational attainment as covariates. All
statistical analyses were conducted using IBM SPSS
Statistics V.19 (IBM Co.).

RESULTSA total of 86 (4.9%) of the 1763 respondents reported
the incidence of multiple falls at the follow-up survey.
Table 1 shows the rates of fallers and non-adjusted ORs
for reporting multiple falls at the follow-up survey
according to dental health variables and covariates.
Univariate models showed that poor dental status,
chewing ability, male sex, older age, lower functional
disability during follow-up period, depression, poor selfrated health and low educational attainment were eachassociated with incident falls.
In the fully adjusted model, subjects with 19 or fewer
teeth without dentures had a 2.50 (95% CI 1.21 to 5.17)fold increased risk for incident falls compared with thosehaving 20 or more teeth(Table 2). No significant association was observed between incident falls and chewing
ability after adding all covariates in the logistic regression model. When the two dental health variables wereentered simultaneously into the same model with fulladjustment for all covariates, there was no change in theORs for any of the dental status variables.
DISCUSSION
Results of the present study showed that subjects with 19
or fewer teeth without dentures had a significantly
higher risk for incident falls than those with 20 or moreteeth, even after adjusting for multiple potential
confounding factors including demographics, physicaland mental health status, and socioeconomic status.
These findings are consistent with those of a 1-year
longitudinal study using 146 older patients with severe
dementia, showing that patients with functionally inadequate dental status had significantly more frequent falls
than those with functionally adequate occlusioncomposed of natural teeth, dentures or both.14 Interestingly, among subjects with 19 or fewer teeth, their riskof falls was not significantly elevated so long as they wore
dentures. These results suggest that the poor dental
occlusion due to not using dentures after losing teeth isa strong risk factor for falls among subjects with 19 or
fewer teeth.
There are several possible pathways between not using
dentures after losing teeth and incident falls. One
possibility is that the loss of occlusion due to not using
dentures may result in a decrease in functional balance
and these functional declines lead to falls. A crosssectional study suggests that dental occlusal condition isassociated with balance function.12 An 8-year longitudinal study showed that partial or complete loss of
occlusion was associated with a decrease in balance
function.13 Because balance deficit is a well-known risk
factor for falls,6 it is plausible that poor balance may
explain the increased risk of falls among subjects withpoor dental occlusion.
A clinical study showed that dental occlusion affects
postural and gaze stabilisation because proprioceptive
receptors of the masticatory muscular system anddentoalveolar ligaments provide sensory afferent input,

Yamamoto T, Kondo K, Misawa J, et al. BMJ Open 2012;2:e001262. doi:10.1136/bmjopen-2012-001262

3

Dental status and incident falls among older Japanese
Table 1 Univariate associations of dental health variables and covariates with incident falls
Totaln
Dental status$20 teeth586#19 teeth with dentures
958#19 teeth without dentures
198
Missing
21
Chewing ability
Can chew anything719
Can chew most foods
935
Cannot chew very well
97
Missing
12
Sex
Female853
Male910
Age (years)
65e69
707
70e74
569
75e79
325
80e84
120
$85
42
Present illness related to falls*
No
1224
Yes
539
Activities of daily living
Without limitation
1669
With limitation or missing
94
Functional disability during follow-up period
No
1734
Yes
29
Body mass index
<18.5
113
18.5e24.9
1196
$25.0
380
Missing74
Use of sedatives
No
1602
Yes
161
Depression
No
1143
Mild
311
Moderate to severe
77
Missing232
Self-rated health
Excellent
162
Good
1192
Fair
321
Poor
59
Missing
29
Exercise (walk in minute/day)
$60
430
30e59
569
<30
564
Missing
200
Frequency of outings
Almost everyday
843
2e3 times a week
532
Once a week or less
335
Missing
53

4

Fallersn (%)

OR (95% CI)

p Value

17 (2.9)49 (5.1)
17 (8.6)
3 (14.3)

1.00
1.80 (1.03 to 3.16)
3.14 (1.57 to 6.28)
5.58 (1.50 to 20.76)

0.039
0.001
0.010

30 (4.2)
47 (5.0)
9 (9.3)0 (0.0)1.00
1.22 (0.76 to 1.94)
2.35 (1.08 to 5.11)
0.00 (0.00)

0.414
0.031
0.999

32 (3.8)
54 (5.9)

1.00
1.62 (1.03 to 2.53)

0.035

23 (3.3)
27 (4.7)
18 (5.5)
12 (10.0)
6 (14.3)

1.00
1.48 (0.84 to 2.61)
1.74 (0.93 to 3.28)
3.30 (1.60 to 6.84)
4.96 (1.90 to 12.93)

0.175
0.084
0.001
0.001

58 (4.7)
28 (5.2)

1.00
1.10 (0.69 to 1.75)

0.682

81 (4.9)5 (5.3)1.00
1.10 (0.44 to 2.79)

0.838

81 (4.7)
5 (17.2)

1.00
4.25 (1.58 to 11.43)

0.004

8 (7.1)52 (4.3)
21 (5.5)5 (6.8)1.68 (0.78 to 3.62)
1.00
1.29 (0.77 to 2.17)
1.59 (0.62 to 4.12)

0.342
0.336

80 (5.0)
6 (3.7)1.00
0.74 (0.32 to 1.72)

0.478

39 (3.4)
21 (6.8)
8 (10.4)
18 (7.8)

1.00
2.05 (1.19 to 3.54)
3.28 (1.48 to 7.29)
2.38 (1.34 to 4.24)

0.010
0.004
0.003

6 (3.7)50 (4.2)
21 (6.5)
9 (15.3)
0 (0.0)1.00
1.14 (0.48 to 2.70)
1.82 (0.72 to 4.60)
4.68 (1.59 to 13.80)
0.00 (0.00)

0.769
0.206
0.005
0.998

20 (4.7)
16 (2.8)
38 (6.7)
12 (6.0)

1.00
0.59 (0.30 to 1.16)
1.48 (0.85 to 2.58)
1.31 (0.63 to 2.73)

0.126
0.167
0.474

37 (4.4)
27 (5.1)
20 (6.0)
2 (3.8)1.00
1.17 (0.70 to 1.94)
1.38 (0.79 to 2.42)
0.85 (0.20 to 3.65)

0.189

0.557
0.256
0.831
Continued

Yamamoto T, Kondo K, Misawa J, et al. BMJ Open 2012;2:e001262. doi:10.1136/bmjopen-2012-001262

Dental status and incident falls among older Japanese
Table 1

Continued

Educational attainment (years)
$13
10e12
6e9
<6
Missing
Equivalised household income (yen)<500 000
500 000e999 999
1 000 000e1 499 999
1500 000e1 999 999
2000 000e2 999 999
3000 000e3 999 999$4000 000
Missing

Total
nFallersn (%)

OR (95% CI)

p Value

184
506
953
53
67

4 (2.2)23 (4.5)
49 (5.1)
4 (7.5)6 (9.0)1.00
2.14 (0.73 to 6.28)
2.44 (0.87 to 6.84)
3.67 (0.89 to 15.22)
4.43 (1.21 to 16.21)

0.165
0.090
0.073
0.025

53
108
139
262
429
263
164
345

0 (0.0)7 (6.5)7 (5.0)15 (5.7)
16 (3.7)
15 (5.7)
5 (3.0)21 (6.1)

0.00 (0.00)
1.00
0.77 (0.26 to 2.25)
0.88 (0.35 to 2.21)
0.56 (0.22 to 1.39)
0.87 (0.35 to 2.20)
0.45 (0.14 to 1.47)
0.94 (0.39 to 2.26)

0.997
0.627
0.780
0.213
0.773
0.187
0.882

*Stroke, osteoporosis, joint disease/neuralgia, injury/fracture, impaired vision and/or impaired hearing.

and hence poor dental occlusion may decrease thatproprioception and interfere with the stability of headposture.15 Another clinical study showed that denture
use improves postural swaying.27 Because using dentures reduced the OR for incident falls in the present
study, proprioceptive receptors of the masticatory
muscular system might be more strongly associated withbalance function and falls than those of dentoalveolar
ligaments.
Some subjects with 20 or more teeth may have had
dentures in the present study; however, the information
was not obtained. Subjects with 20 or more teeth without
dentures may be more appropriate than those with 20 ormore teeth with/without dentures as a reference, andlack of the information might underestimate the association between dental status and incident falls.
However, studies show that people having at least 20
teeth usually can eat anything even they do not ware
dentures.28 29 Therefore, the lack of the information of
with/without dentures in subjects having 20 or moreteeth may be negligible.
We excluded individuals with history of falls because
we wanted to examine prospectively the risk of incident
falls. In addition, there is a theoretical possibility that
history of falls might confound the association between
number of teeth and risk of future falls, that is, history offalls in the past can be a prior common cause of (1)number of teeth (because some people may break teeth
when they fall) and (2) past falls predict future falls. For
these reasons, we felt that it was justified to exclude thosewith fall history at baseline.
In the present study, self-reported chewing ability was
not associated with the incident falls. This result
disagreed with those from a cross-sectional study
showing a significant association between chewing ability
judged from number of foods chewable and one-leg
standing time.30 Because self-reported mastication canbe modified by cooking (eg, cooking soft meal helps

chewing ability) and is more subjective than selfreported number of teeth present and denture use, thismight dilute the association between self-reported
chewing ability and the incident falls. A study using 5643
subjects aged 40e89 years showed that number of functional teeth which differentiate subjects with and without
subjective dysphagia, defined as suffering any kind of
subjective impairment to eating function, including
biting difficulty, declined with age.31 Additional studies
using objective measures for chewing ability are required
to clarify the relationship between chewing ability andthe incident falls.
Using dentures does not always recover chewing
ability. For example, a cross-sectional study showed that
biting forces among removable partial and complete
denture wearers were 35% and 11%, respectively, when
expressed as a percentage of the subjects with naturaldentition.32 These results may explain the different
associations of dental status and chewing ability withincident falls in the present study. When both dental
status and chewing ability were simultaneously enteredin the fully adjusted logistic regression model in thepresent study, only dental status was still significantly
associated with incident falls.
Men were at increased risk of falls in the present study,
which disagrees with a meta-analysis7 based on people
aged 60 years or older showing that female sex was a risk
factor. On the other hand, our study result is also similar
to another large study of 12 684 individuals aged 85 years
or older.21 We feel that the association between sex andrisk of falls might vary according to the study population.
Indeed, current clinical guidelines for the prevention of
falls do not include sex as a risk factor,6 33 and thus it
may not be a settled question.
Strengths and limitations
We note some strength of the present study including
large sample size, population-based sampling andYamamoto T, Kondo K, Misawa J, et al. BMJ Open 2012;2:e001262. doi:10.1136/bmjopen-2012-001262

5

Dental status and incident falls among older Japanese
Table 2 Multivariate adjusted OR and 95% CI for the association of dental status and chewing ability with incident falls
OR (95% CI)
Dental status$20 teeth
1.00#19 teeth with dentures
1.36 (0.76 to 2.45)#19 teeth without dentures
2.50 (1.21 to 5.17)
Missing5.75 (1.23 to 26.78)
Chewing ability
Can chew anything
Can chew most foods
Cannot chew very well
Missing
Sex
Female1.00
Male
1.86 (1.16 to 2.96)
Age (years)
65e69
1.00
70e74
1.31 (0.73 to 2.34)
75e79
1.42 (0.74 to 2.74)
80e84
2.51 (1.17 to 5.39)$85
3.78 (1.27 to 11.19)
Functional disability during follow-up period
No
1.00
Yes
2.30 (0.75 to 7.06)
Depression
No
1.00
Mild
1.82 (1.01 to 3.26)
Moderate to severe
2.47 (1.02 to 5.97)
Missing
2.14 (1.09 to 4.17)
Self-rated health
Excellent
1.00
Good
1.14 (0.47 to 2.77)
Fair
1.43 (0.54 to 3.78)
Poor
2.71 (0.83 to 8.77)
Missing
0.00 (0.00)
Educational attainment (years)
$13
1.00
10e12
2.49 (0.83 to 7.45)
6e9
2.21 (0.77 to 6.33)<61.77 (0.37 to 8.56)
Missing
2.78 (0.68 to 11.38)

control for many potential confounding factors.
However, the present study has a number of limitations.
First, measurement of dental status was based on selfreport, not based on clinical examination. However, thevalidity and reliability of self-reported number of teeth
has been established by multiple studies and widely usedin epidemiological surveys.34 For example, validation
studies in the USA and Japan have reported a highagreement between self-reported and examined numberof teeth (Pearson’s correlation coefficient: r¼0.97 and
0.93, respectively) in 50 community-dwelling individuals
aged 70 years or older and 2496 subjects with a mean ageof 59.35 36 Second, self-report of falls may not be
perfectly accurate.37 However, the associations withdemographic factors and other covariates are in thegenerally expected direction, suggesting that there may
be sufficient value in this outcome.
6

p Value

OR (95% CI)

p Value

1.00
0.97 (0.59 to 1.59)
1.47 (0.64 to 3.37)
0.00 (0.00)

0.910
0.361
0.999

0.010

1.00
1.86 (1.16 to 2.96)

0.009

0.366
0.290
0.018
0.017

1.00
1.36 (0.76 to 2.42)
1.57 (0.82 to 3.02)
2.84 (1.34 to 6.04)
4.63 (1.59 to 13.49)

0.302
0.178
0.007
0.005

0.144

1.00
2.11 (0.70 to 6.37)

0.184

0.046
0.045
0.026

1.00
1.82 (1.01 to 3.26)
2.49 (1.03 to 6.02)
2.07 (1.06 to 4.04)

0.045
0.042
0.032

0.767
0.474
0.097
0.998

1.00
1.07 (0.44 to 2.59)
1.33 (0.50 to 3.54)
2.60 (0.81 to 8.34)
0.00 (0.00)

0.877
0.568
0.109
0.998

0.102
0.140
0.476
0.156

1.00
2.59 (0.87 to 7.72)
2.50 (0.87 to 7.12)
2.24 (0.49 to 10.27)
3.17 (0.77 to 13.01)

0.089
0.087
0.299
0.110

0.299
0.013
0.026

CONCLUSIONSThe primary implication of this study is the importanceof maintaining the dental occlusion, especially withnatural teeth, in order to prevent falls among older
adults. The loss of teeth might be an independent risk
factor for incident falls, but it could be prevented byusing dentures. Promoting dental care including properuse of denture might be an additional option for theprevention of falls in addition to current interventions
targeting conventional risk factors, which warrants
further interventional studies testing the effects ofdental care and denture use on the prevention of falls.
Author affiliations
1
Division of Sociological Approach in Dentistry, Department of Dental
Sociology, Kanagawa Dental College, Yokosuka-shi, Kanagawa, Japan
2
Center for Well-being and Society, Nihon Fukushi University, Nagoya-shi,
Aichi, Japan

Yamamoto T, Kondo K, Misawa J, et al. BMJ Open 2012;2:e001262. doi:10.1136/bmjopen-2012-001262

Dental status and incident falls among older Japanese
3

Department of Civil and Environmental Engineering, Faculty of Engineering,
Iwate University, Morioka-shi, Iwate, Japan
4
Department of Nutrition, Faculty of Health and Nutrition, Tokaigakuen
University, Nagoya-shi, Aichi, Japan
5
Department of International and Community Oral Health, Tohoku University
Graduate School of Dentistry, Sendai-shi, Miyagi, Japan
6
Department of Health Sciences, Interdisciplinary Graduate School of Medicine
and Engineering, University of Yamanashi, Chuo-shi, Yamanashi, Japan
7
Department of Society, Human Development and Health, Harvard School of
Public Health, Boston, Massachusetts, USA

11.
12.
13.
14.
15.

Contributors TY and YH had the idea for the study, participated in its design,
performed the statistical analysis and drafted the manuscript, and YH is theguarantor. KK is coordinator of Aichi Gerontological Evaluation Study Project,helped develop the idea of the study, participated in acquiring the data andwith design and edited the manuscript. JM participated in design of study andedited the manuscript. HH and MN participated in acquiring the data and withdesign and critically revised the manuscript. JA, NK and IK participated in thedesign of the study, deciding on statistical methods used, helped ininterpreting the results and revising the manuscript.
Funding This study was supported in part by a grant of the Strategic Research
Foundation Grant-aided Project for Private Universities from Ministry of
Education, Culture, Sport, Science and Technology, Japan (MEXT),
2009e2013, and Health Labour Sciences Research Grant, Comprehensive
Research on Aging and Health (H22-Choju-Shitei-008) from the Japanese
Ministry of Health, Labour and Welfare.

16.

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21.

Competing interests None.

22.

Ethical approval The Aichi Gerontological Evaluation Study protocol including
the present study was reviewed and approved by the Ethics Committee on
Research of Human Subjects at Nihon Fukushi University.

23.

Provenance and peer review Not commissioned; externally peer reviewed.

24.

Data sharing statement No additional data available.
25.

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