Flossing Is Associated with Improved Oral Health in Older Adults

Abstract

The effect of preventive oral habits is largely unexplored in older individuals. The purpose of this study was to evaluate the associations between home use of flossing and prevalence of periodontal disease and caries in older adults. Five-year incident tooth loss was also evaluated. Data on 686 individuals ≥65 y-old from the Piedmont 65+ Dental Study were examined including: 1) interproximal clinical attachment level (iCAL), 2) interproximal probing depth (iPD), 3) numbers of caries, and 4) missing teeth. Flossing behavior was evaluated according to the Periodontal Profile Class (PPC) system. Five-year follow-up data ( n = 375) was evaluated for incident tooth loss. Dichotomous and categorical variables were analyzed using Pearson chi-square tests as well as covariate-adjusted Cochran-Mantel-Haenszel tests. Multiple linear regression compared clinical parameters based on flossing behavior. Elderly flossers had lower (mean, SE) %iCAL≥3 mm (38.2, 2.38 vs. 48.8, 1.56) and %iPD≥4 mm (8.70, 1.41 vs. 14.4, 0.93) compared to nonflossers ( P ≤ 0.005). Flossers showed less coronal caries compared to nonflossers ( P = 0.02). Baseline number of missing teeth (mean, SE) was 11.5 (0.35) in nonflossers compared to 8.6 (0.53) in flossers ( P < 0.0001). Regular dental visitors had lower oral disease levels compared to episodic dental users. The majority of flossers classified into PPC-Stage I (health) whereas nonflossers classified as PPC-Stages V, VI, and VII (disease). At the 5-y follow-up visit, the average tooth loss for flossers was ~1 tooth compared to ~4 teeth lost for nonflossers ( P < 0.0001). Among all teeth, molars showed the highest benefit (>40%) for flossing behavior ( P = 0.0005). In conclusion, the extent of oral disease for older individuals was significantly less in flossers than in nonflossers. Flossers showed less periodontal disease, fewer dental caries, and loss of fewer teeth over a 5-y period. These findings further support flossing as an important oral hygiene behavior to prevent oral disease progression in older adults.

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https://doi.org/10.1177/0022034520916151
Journal of Dental Research
2020, Vol. 99(9) 1047 –1053
© International & American Associations
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Research Reports: Clinical
Introduction
With the world population aging, there is a growing focus on
what constitutes health in older adult populations (World
Health Organization 2015). Good oral health is considered a
key factor in healthy ageing and is associated with improved
general health, reduced morbidity and mortality in older adults
(Holm-Pedersen et al. 2008; Tonetti et al. 2017). Since there is
a consistent peak of severe tooth loss at the age of 65 over the
past 2 decades, it is important to understand whether preven-
tive oral hygiene regimens in older adults can improve oral
health and tooth retention (Tonetti et al. 2017).
The key to promoting optimal oral health in older adults is
to control its two most common diseases—periodontal disease
and caries—which are chronic multifactorial diseases of which
microbial biofilm are a fundamental etiology (Loe et al. 1965;
Beck and Drake 1975; Listgarten et al. 1975; Hunt et al. 1992;
Guggenheim et al. 2004; Socransky and Haffajee 2005; Curtis
et al. 2011; Hajishengallis et al. 2012; Jiao et al. 2013; Teles
et al. 2013; Takahashi 2015; Sanz et al. 2017). A change in the
microbial communities (dysbiosis) of the tooth-adherent dental
plaque is consistently related to the progression from oral
health to disease (Feres et al. 2016; Sanz et al. 2017). Therefore,
the mechanical disruption of microbial biofilm’s adherence to
the tooth by toothbrushing and interdental cleaning is recom-
mended as part of home care (Jepsen et al. 2017).
There is a need for epidemiological surveillance of oral dis-
ease and tooth loss in older populations (Tonetti et al. 2017).
We and others have previously addressed the challenges of
conducting randomized clinical trials to evaluate prevention of
oral disease by flossing/interdental cleaning, which include a)
916151JDRXXX10.1177/0022034520916151Journal of Dental ResearchFlossing and Elderly Adult Oral Health
research-article2020
1Department of Comprehensive Oral Health, Adams School of Dentistry,
University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
2Department of Oral and Craniofacial Health Sciences, Adams School of
Dentistry, University of North Carolina at Chapel Hill, Chapel Hill, NC,
USA
3Department of Biostatistics, Gillings School of Global Public Health,
University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
4Department of Comprehensive Care, School of Dental Medicine, Tufts
University, Boston, MA, USA
A supplemental appendix to this article is available online.
Corresponding Author:
J.T. Marchesan, Department of Comprehensive Oral Health,
Periodontology, Adams School of Dentistry, University of North
Carolina at Chapel Hill, 3506 Koury Oral Health Sciences Building,
Campus Box #7455, Chapel Hill, NC 27599-7455, USA.
Email: julie_marchesan@unc.edu
Flossing Is Associated with Improved
Oral Health in Older Adults
J.T. Marchesan1, K.M. Byrd2, K. Moss2, J.S. Preisser3, T. Morelli1,
A.F. Zandona4, Y. Jiao1, and J. Beck1
Abstract
The effect of preventive oral habits is largely unexplored in older individuals. The purpose of this study was to evaluate the associations
between home use of flossing and prevalence of periodontal disease and caries in older adults. Five-year incident tooth loss was also
evaluated. Data on 686 individuals ≥65 y-old from the Piedmont 65+ Dental Study were examined including: 1) interproximal clinical
attachment level (iCAL), 2) interproximal probing depth (iPD), 3) numbers of caries, and 4) missing teeth. Flossing behavior was
evaluated according to the Periodontal Profile Class (PPC) system. Five-year follow-up data (n = 375) was evaluated for incident tooth
loss. Dichotomous and categorical variables were analyzed using Pearson chi-square tests as well as covariate-adjusted Cochran-Mantel-
Haenszel tests. Multiple linear regression compared clinical parameters based on flossing behavior. Elderly flossers had lower (mean, SE)
%iCAL≥3 mm (38.2, 2.38 vs. 48.8, 1.56) and %iPD≥4 mm (8.70, 1.41 vs. 14.4, 0.93) compared to nonflossers (P ≤ 0.005). Flossers showed
less coronal caries compared to nonflossers (P = 0.02). Baseline number of missing teeth (mean, SE) was 11.5 (0.35) in nonflossers
compared to 8.6 (0.53) in flossers (P < 0.0001). Regular dental visitors had lower oral disease levels compared to episodic dental users.
The majority of flossers classified into PPC-Stage I (health) whereas nonflossers classified as PPC-Stages V, VI, and VII (disease). At the
5-y follow-up visit, the average tooth loss for flossers was ~1 tooth compared to ~4 teeth lost for nonflossers (P < 0.0001). Among all
teeth, molars showed the highest benefit (>40%) for flossing behavior (P = 0.0005). In conclusion, the extent of oral disease for older
individuals was significantly less in flossers than in nonflossers. Flossers showed less periodontal disease, fewer dental caries, and loss
of fewer teeth over a 5-y period. These findings further support flossing as an important oral hygiene behavior to prevent oral disease
progression in older adults.
Keywords: OHI, interdental cleaning, elderly, prevention, periodontal disease, caries

1048 Journal of Dental Research 99(9)
ethical reasons of assigning individuals into a nonflossing regi-
men, b) amount of time required for the development of caries
and periodontal disease, and c) funding issues to support this
type of study (Vernon et al. 2017; Vernon and Seacat 2017;
Marchesan et al. 2018). Randomized controlled trials (RCTs)
are often expensive and some fail to generate useful evidence
for clinical practices (Mc Cord et al. 2018). Other types of
studies that are used to measure the effectiveness of an inter-
vention include observational studies that represent non-
experimental “real world” scenarios at the population level
(Anglemyer et al. 2014). Previous evaluations by our group of
available cross-sectional data from the National Health and
Nutrition Examination Survey (NHANES 2011–2012 and
2013–2014) showed that interdental cleaning was associated
with less oral disease, including caries, periodontal disease
parameters, and number of teeth (Marchesan et al. 2018).
While this study evaluated a large number of individuals (n =
6,891), it did not provide longitudinal information. In addition,
the NHANES study surveys adults aged over 30 y of age, with
a mean age of ~50 y of age (Marchesan et al. 2018) and does
not directly address older individuals who live in the commu-
nity. In children, professional flossing done for 1.7 y reduced
the risk for developing caries by 40% (Hujoel et al. 2006), and
recent analysis of multiple RCTs showed that the usage of
floss—in addition to toothbrushing—in adults may reduce gin-
givitis or plaque compared to brushing alone at 1, 3, and 6 mo
(Worthington et al. 2019). This emerging evidence further sup-
ports flossing as an effective intervention for reducing the bur-
den of oral disease.
The purpose of this study was to evaluate the associations
between home use of flossing and prevalence of periodontal
disease and caries in older adults. Five-year incident tooth loss
was also evaluated. We hypothesized that elderly individuals
who flossed had improved oral health and lost less teeth over a
5-y period when compared to nonflossers. In this present study,
we accessed longitudinal data available from the Piedmont 65+
Dental Study (Dental PDS) that collected data from individuals
aged ≥65 y over a 5-y period. We evaluated if flossing, in addi-
tion to tooth brushing, was associated with a) less periodontal
disease, b) fewer coronal and interproximal caries, and c)
fewer teeth lost over a 5-y period when compared to brushing
alone.
Methods
The Piedmont Health Study of the Elderly is the parent study
of the Piedmont 65+ Dental Study (Dental PDS) and was a
cohort of the health status of a random sample of non-
institutionalized people aged ≥65 in five contiguous North
Carolina counties (Brown et al. 1994; Beck et al. 1997). In
1988 the University of North Carolina initiated Dental PDS
from the parent population, which selected a random sub-sample
stratified on dentate status and race. The study conforms to
STROBE guidelines. Dental examinations and interviews
were conducted in the home (private residence) of the partici-
pants by one of five calibrated examination teams composed
of a dentist-examiner and a recorder. Dental examinations
were conducted at baseline (1988) and at 5 y (1993) using the
same methodology. Detailed descriptions of the study sam-
pling methods are published elsewhere (Graves et al. 1992;
Drake et al. 1994). Clinical measurements (probing depth and
clinical attachment level) were evaluated at the mesial-buccal
and buccal region of all present teeth (up to 32 teeth). A total
of 686 individuals were evaluated based on the available clini-
cal data: percent of sites with interproximal clinical attach-
ment levels (iCAL)≥3 mm, percent of sites with interproximal
probing depth (iPD)≥4 mm, number of coronal and interproxi-
mal caries (unfilled), number and type of lost teeth in a 5-y
period. A PD≥4 mm and a CAL≥3 mm were selected based on
previous studies using these as variables for periodontal
pathologic features, including our previous study that evalu-
ated the interdental cleaning behavior of NHANES partici-
pants (Moss et al. 2009; Akinkugbe et al. 2017; Marchesan
et al. 2018).
To evaluate the influence of the behavior on current peri-
odontal disease classification systems, we used the PPC-Stages
classification developed at the University of North Carolina at
Chapel Hill (Morelli et al. 2017; Beck et al. 2018; Morelli
et al. 2018). The PPC-Stages classification is based on number
of teeth, crowns, probing depth, clinical attachment level,
bleeding on probing, plaque index, and gingival index that are
imputed into an algorithm and classify individuals into 7 cate-
gories [from PPC-Stage I (Health) to Stage VII (Severe tooth
loss)] (Morelli et al. 2017; 2018). Information for decayed,
interproximally decayed, and missing teeth was evaluated for
686 individuals. Longitudinal information on the number of
teeth at 60-mo (5-y) was utilized for the tooth loss analysis
(n = 375).
Flossing exposure was assessed based on the question: “Do
you use dental floss? How often?”. The following answers
were given as options: Answer: “A) Not at all, B) Daily (7
times per week), C) Several times per week (2 to 6 times), D)
One time per week, E) Less often than once per week”.
Individuals were divided into 2 main categories of nonflossers
(response A) Not at all) and flossers (responses B–E).
Dental utilization (dental treatment) was assessed based on
the following question: “Would you say that you use a dentist
on a regular basis, or do you only go when you are in discom-
fort or when you need something fixed?”. The answers given
as options were: “A) Regular basis, B) Only when in discom-
fort, C) When something needs to be fixed, D) Don’t go to the
dentist”. Individuals were divided into 2 categories of regular
users (response A) Regular basis) and episodic (responses
B–D).
Statistical Analysis
Pearson chi-square tests were used to compare demographic
variables between flossers and nonflossers. Multiple linear
regression adjusted for race, sex, age, diabetes, smoking, edu-
cation, brushing, and dental utilization was used to compare
clinical parameters based on flossing behavior. Sensitivity

Flossing and Elderly Adult Oral Health 1049
analysis was done to account for individuals who were lost to
follow-up at the 5-y visit. Five-year tooth loss models were
weighted using the inverse of the predicted probability of being
followed versus dropout using study demographics.
Results
Demographics and Clinical Characterization
The baseline demographics of the individuals included in the
study varied by flossing behavior (Table 1). Mean age was
slightly higher in nonflossers than flossers (73.6 vs. 72.3, P =
0.002). Compared to flossers, a higher percentage of non-
flossers were African Americans, males, diabetic, had a basic
education and infrequent dental visits. Conversely when com-
pared to nonflossers, a higher percentage of flossers were
Caucasians, females, non diabetic, with advanced education,
and regular dental visits when compared to nonflossers (Table
1). Nonflossers had a greater tendency to be smokers than floss-
ers, but the difference was not statistically significant (P = 0.57).
For the analysis at 5 y, 311 (45.3%) individuals were lost to
follow-up. Younger individuals, females, and those with regu-
lar dental utilization were statistically significantly more likely
to have completed the 5-y follow-up (Appendix Table 1). The
most frequent reason that individuals did not complete the 5-y
follow-up visit was death (n = 121, 38.9%; Appendix Table 2).
Flossing and Oral Disease
Our analysis shows that individuals identified as flossers dem-
onstrated a statistically significant lower number of sites with
interproximal clinical parameters of periodontal disease
(iCAL≥3 mm, iPD≥4 mm; Table 2). In addition, individuals
who flossed also had less coronal caries (P = 0.02) and a trend
for fewer interproximal caries (P = 0.06, Table 2). Individuals
who flossed also showed significantly lower numbers of miss-
ing teeth even when third molars were excluded (P < 0.0001).
Mean number of missing teeth excluding third molars in non-
flossers was 11.5 (0.35) compared to 8.6 (0.53) in flossers
(Table 2).
Table 3 stratifies the relationships from Table 2 by regular
and episodic dental use. In general, episodic dental users have
higher levels of disease than regular dental users. Table 3 indi-
cates that periodontal parameters of iCAL and iPD were sig-
nificantly lower only for flossers compared to nonflossers that
were regular dental users, with a similar trend that did not
reach statistical significance observed for episodic dental
users. On the other hand, flossers who were episodic dental
users had significantly fewer coronal carious lesions with a
non significant similar trend for regular dental users.
Interproximal caries surfaces did not show significant differ-
ences between flossers and nonflossers, but a strong trend
favoring flossers was seen in episodic dental users (Table 3, P
= 0.06). Flossing behavior favored numbered of teeth regard-
less of the dental utilization, with flossers having an additional
~2 teeth if they were episodic dental users and ~3.5 teeth if
they were regular dental users (Table 3).
We then evaluated the distribution of individuals based on
different periodontal disease classification systems and strati-
fied these classes by flossing behavior. When comparing floss-
ing behavior categories using the PPC-Stages classification
system, flossers were more likely to be PPC-Stage I Health
(Table 4). Nonflossers were more likely to be Stage V, VI, and
VII of disease (Table 4).
Flossing and 5-y Tooth Loss
We evaluated the number of individuals that had lost teeth for
each oral hygiene regimen group (flossers and nonflossers)
during the 5-y period. The majority of individuals (regardless
of their flossing habit) retained their teeth rather than losing
one or more tooth, with a range of 58.6% to 91.9% individuals
retaining their teeth between both flossing categories (Table 5).
Overall, the percent of individuals retaining their teeth was sig-
nificantly higher among flossers. This pattern was true when
evaluating individuals retaining all incisors, canines, and
Table 1. Demographics According to Flossing Behavior (n = 686).
Nonflossers Flossers P Value
Age, y, mean (SD) 73.6 (5.9) 72.3 (5.0) 0.002
African American 315 (68.2) 64 (28.6) <0.0001
Caucasian 147 (31.8) 160 (71.4)
Female 247 (53.5) 153 (68.3) 0.0002
Male 215 (46.5) 71 (31.7)
Diabetics 92 (20.0) 27 (12.1) 0.01
Nondiabetic 369 (80.0) 197 (88.0)
Smoker 93 (20.1) 41 (18.3) 0.57
Nonsmoker 369 (79.9) 183 (81.7)
Basic Education 395 (85.9) 109 (48.7)
<0.0001Intermediate Education 29 (6.3) 44 (19.6)
Advanced Education 36 (7.8) 71 (31.7)
Episodic dental utilization 362 (80.8) 49 (21.9) <0.0001
Regular dental utilization 86 (19.2) 175 (78.1)
Data are presented as n (%) unless otherwise indicated.
Table 2. Clinical Parameters (mean, SE) of Periodontal Disease, Caries,
and Number of Missing Teeth Stratified by Flossing Behavior
(n = 686).
Nonflossers Flossers P Value
iCAL≥3 mm (% sites) 48.8 (1.56) 38.2 (2.38) 0.0008
iPD≥4 mm (% sites) 14.4 (0.93) 8.70 (1.41) 0.002
Coronal caries (surfaces) 1.16 (0.10) 0.66 (0.16) 0.02
Interproximal caries (surfaces) 0.56 (0.06) 0.35 (0.08) 0.06
Missing teeth (n) 14.7 (0.38) 11.8 (0.58) 0.0001
Missing teeth (n excluding third
molars)
11.5 (0.35) 8.6 (0.53) <0.0001
Means adjusted for race, sex, age, diabetes, smoking, education, brushing,
and dental utilization; P values based on multiple linear regression.
iCAL, interproximal clinical attachment level; iPD, interproximal probing
depth.

1050 Journal of Dental Research 99(9)
premolars (P < 0.0001 for each category) with a similar trend
for individuals retaining all molars (P = 0.08) (Table 5).
In addition, we further analyzed the impact of flossing
behavior over the 5-y period in the mean number and type of
teeth that were lost. Because we identified a relatively large
percentage of dropouts, we present the weighted sensitivity
analysis results in Table 6. Unweighted analysis demonstrates
nearly identical results (data not shown). Elderly flossers lost
fewer teeth across all tooth types (molars, premolars, canines,
and incisors), with an average loss of ~1 tooth compared to ~4
teeth lost in nonflossers over the 5-y period (P < 0.0001, Table
6). Nonflossers showed 18.7%, 23.9%, and 21.8% increased
tooth loss for premolars, canines, and incisors, respectively
(Table 6). The most dramatic difference between groups was
identified for molars, with 41.6% increase of loss in non-
flossers compared to flossers in the 5-y period (Table 6).
Discussion
Older individuals have higher levels of oral disease overall as
a reflection of time of exposure to multiple risk factors (Tonetti
et al. 2017). Preservation of a functional dentition into old age
is possible and provides benefits in the overall quality of life of
an individual (Holm-Pedersen et al. 2008). This current study
Table 3. Clinical Parameters (mean, SE) of Periodontal Disease, Caries, and Number of Missing Teeth Stratified by Dental Visits and Flossing Behavior
(n = 686).
Episodic Dental Users Regular Dental Users
Nonflossers Flossers P Value Nonflossers Flossers P Value
iCAL≥3 mm (% sites) 56.3 (1.72) 46.2 (4.86) 0.051 38.1 (2.90) 25.7 (1.99) 0.0007
iPD≥4 mm (% sites) 17.8 (1.11) 13.1 (3.13) 0.17 9.46 (1.29) 3.02 (0.88) <0.0001
Coronal caries (surfaces) 1.64 (0.13) 0.63 (0.38) 0.01 0.23 (0.06) 0.13 (0.04) 0.20
Interproximal caries (surfaces) 0.81 (0.07) 0.39 (0.20) 0.06 0.12 (0.04) 0.05 (0.02) 0.15
Missing teeth (n) 15.9 (0.42) 13.4 (1.17) 0.049 13.3 (0.70) 9.70 (0.48) <0.0001
Missing teeth (n excluding third molars) 12.7 (0.38) 10.5 (1.08) 0.054 10.0 (0.67) 6.35 (0.46) <0.0001
Means adjusted for race, sex, age, diabetes, smoking, education, brushing, and dental utilization; P values based on multiple linear regression.
iCAL, interproximal clinical attachment level; iPD, interproximal probing depth.
Table 4. Periodontal Disease Classification Systems by Flossing Behavior (n = 686).
PPC-Stages Nonflossers Flossers Chisq/CMH P Value
n462 224
Stage I (health) 45 (9.7) 90 (40.2) <0.0001/<0.0001
Stage II Mild 19 (4.1) 12 (5.4)
Stage III Moderate 4 (0.9) 2 (0.9)
Stage IV Severe 41 (8.9) 7 (3.1)
Stage V Mild TL-Hi GI 128 (27.7) 56 (25.0)
Stage VI Mod TL-Red 121 (26.2) 34 (15.2)
Stage VII Severe TL 104 (22.5) 23 (10.3)
Comparison of observed frequencies is based on unadjusted Pearson chi-square tests (first P value) and Cochran-Mantel-Haenszel (CMH) tests
(second P value) adjusted for race, sex, age, diabetes, smoking, education, brushing, and dental utilization. Data are presented as n (%).
GI, gingival index; Hi, high; Mod, moderate; Red, reduced periodontium; TL, tooth loss.
Table 5. Percent of Individuals Losing Teeth Over 5-y by Tooth Type and Flossing Habit (Including Individuals Who Became Edentulous) n = 375.
Nonflossers Flossers Chisq/CMH P Values
All molars retained 147 (61.5) 96 (70.6) 0.08/0.01
1+ molar(s) lost 92 (38.5) 40 (29.4)
All premolars retained 140 (58.6) 112 (82.4) <0.0001/0.0002
1+ premolar(s) lost 99 (41.4) 24 (17.7)
All canines retained 148 (61.9) 125 (91.9) <0.0001/<0.0001
1+ canine(s) lost 91 (38.1) 11 (8.1)
All incisors retained 141 (59.0) 119 (87.5) <0.0001/<0.0001
1+ incisor(s) lost 98 (41.0) 17 (11.5)
Comparison of observed frequencies is based on unadjusted Pearson chi-square tests (first P value) and Cochran-Mantel-Haenszel (CMH) tests
(second P value) adjusted for race, sex, age, diabetes, smoking, education, brushing, and dental utilization. Data are presented as n (%).

Flossing and Elderly Adult Oral Health 1051
evaluates a preventive oral health behavior in older individu-
als, which are still relatively neglected in the dental field of the
aging world (Tonetti et al. 2017). We provide an assessment of
the impact of flossing behavior in community-dwelling people
aged <65 y. Our results show that flossing was associated with
improved oral health measures. This conclusion is consistent
with our previous study that evaluated data from NHANES in
>6,000 US adults aged ≥30 y that identified that interdental
cleaning was associated with less sites with iCAL≥3 mm,
iPD≥4 mm, coronal caries, icaries, and more present teeth
compared to individuals identified as non-interdental cleaners
(Marchesan et al. 2018). It is important to note that flossing
may be heavily influenced by a healthy lifestyle that in turn
could be influenced by socioeconomic status and educational
levels and other factors that result in an individual’s habits.
Although our study cannot establish causal relation, multiple
difficulties in conducting RCTs to address the benefits of inter-
dental cleaning exist, including allowing time for disease to
develop. Until such trials are conducted, longitudinal studies
are the best level of evidence available to assess potential risk
associated with tooth loss. Our results in no way assume cau-
sality of the association we found. It simply means that by
adjusting to these social and demographic characteristics,
flossing is associated with lower future tooth loss. While the
question addressing the practice of the oral regimen was dis-
tinct between studies (NHANES analysis addressed all forms
of interdental cleaning and the current PDS addressed specifi-
cally flossing), both studies concluded that a person who has
the habit of cleaning between their teeth at least 1x/week
exhibited less oral disease. Therefore, improved oral health
measurements were identified in adults (aged ≥30 y) and older
adults (aged ≥65 y) that reported having a type of interdental
cleaning behavior.
The periodontal disease parameters of iCAL≥3 mm and
iPD≥4 mm selected to be used in the present study have been
previously used in other studies (Moss et al. 2009; Akinkugbe
et al. 2017; Marchesan et al. 2018) and have the advantage of
being translated to a clinical meaning independent of disease
classifications that change over time. In addition to the peri-
odontal phenotype discussed above, we evaluated the number
of individuals distributed among periodontal disease catego-
ries based on flossing behavior. For this analysis, we used the
PPC-Stages classification (Morelli et al. 2017; Beck et al.
2018; Morelli et al. 2018). Since this classification was recently
proposed, there are currently not many studies utilizing these
outcomes to evaluate data. Our data show that the majority of
flossers were PPC-Stage I (PPC-Stages classification) and
majority of nonflossers were PPC-Stage V, VI, and VII. Other
cross-sectional studies that evaluated the association of
flossing/interdental cleaning with a periodontal disease classi-
fication include the analysis of the NHANES 2011–2014 pop-
ulation by Cepeda (Cepeda et al. 2017) and our group
(Marchesan et al. 2018). When periodontitis was defined by
the Centers for Disease Control and Prevention (CDC) defini-
tion (combining mild, moderate, and severe periodontitis),
flossing was associated with a modestly lower prevalence of
periodontitis (Cepeda et al. 2017). When the PPC-Stages clas-
sification was applied to the same NHANES dataset, the
majority of individuals were distributed under the PPC-A
Health category (Marchesan et al. 2018). Within the limitations
of any cross-sectional analysis, our results support an associa-
tion of healthy periodontal categories and flossing behavior.
In the current study we further stratified the clinical data
based on frequency of dental appointments (dental use) as this
may affect the oral health of flossers and nonflossers. The
results showed that the preventive oral health behaviors of den-
tal visits and flossing correlated with elderly individuals hav-
ing less oral disease. These results are in accordance to other
previous reports (Dolan and Atchison 1993; Yellowitz and
Schneiderman 2014; Lee et al. 2019). Recent analysis of 3,255
elderly Koreans (aged 55 to 79 y) identified that toothbrushing
frequency and frequent dental visits (within 1 y) were also cor-
related with number of existing teeth (Lee et al. 2019).
Together, the data further support interventions aimed at pre-
serving existing teeth in the elderly population.
Tooth loss is the final negative outcome that can occur with
the presence of caries and periodontal disease. Tooth loss can
lead to loss of masticatory function, loss of self-esteem, and
decreased quality of life. It has been previously shown that the
most commonly missing teeth are the molars (Marcus et al.
1996) due to the multirooted nature of the teeth and the diffi-
culty of accessing the teeth. In accordance, our data shows that
molars were the tooth type with the greatest flossing benefit
seen over the 5-y period. It is important to note that the indi-
viduals included in the present study lived in the community.
Individuals that moved to a setting of assisted care living (due
to physical and/or mental conditions) were excluded from the
study. Therefore, the elderly individuals included in the present
study were more likely to be capable of being compliant with
self-oral hygiene regimens, more similar to younger adults.
Table 6. Mean (SE) 5-y Tooth Loss by Tooth Type and Flossing Habit (Including People Who Became Edentulous) n = 375.
Nonflossers (n = 239) Flossers (n = 136) P Value Difference
All Teeth 4.22 (0.34) 1.16 (0.47) <0.0001 27.49%
Molars 1.20 (0.12) 0.50 (0.14) <0.0005 41.67%
Premolars 1.28 (0.12) 0.24 (0.16) <0.0001 18.75%
Canines 0.71 (0.07) 0.17 (0.09) <0.0001 23.94%
Incisors 1.60 (0.14) 0.35 (0.19) <0.0001 21.88%
Means adjusted for race, sex, age, diabetes, smoking, education, brushing, and dental utilization via multiple linear regression. Sensitivity analysis
accounted for loss to follow-up.

1052 Journal of Dental Research 99(9)
Cognitive impairment and dementia that can occur with aging
are known to lead to the inability to accurately perform self-
care and increase the prevalence of oral disease (Ellefsen et al.
2009; Teng et al. 2016; Delwel et al. 2017).
There are some limitations to our study. Firstly, we must
note that the individuals enrolled in this study that initiated in
1988 likely had less access to preventive oral health approaches
compared to today. Therefore, the results of this study may not
completely represent results from a present-day study.
Additionally, loss to follow-up due to death is an undesired
outcome that can occur at a higher rate in elderly individuals
for obvious reasons and can produce biased results. Therefore,
to address this, we included the weighted sensitivity analysis
(Table 5). After this adjustment, the results remained nearly
identical supporting that elderly flossers lost fewer teeth across
all tooth types (molars, premolars, canines, and incisors), with
an average loss of ~1 tooth compared to ~4 teeth lost in non-
flossers over the 5-y period. Finally, the study is based on the
report of the individual regarding their flossing behavior. This
approach can influence the hygiene habits of an individual. It
also permits individuals to provide untruthful answers, which
is not an uncommon behavior observed by dentists and dental
hygienists. However, this longitudinal study showed that floss-
ing was negatively related to tooth loss and a false report of
flossing would bias in the other direction. Thus, this may be a
conservative estimate of the relationship between flossing and
tooth loss.
Together, our data show that older individuals who live in
the community and floss one or more times per week have
lower clinical measures of periodontal disease, fewer caries,
and a higher number of teeth. At the 5-y follow-up visit, the
average loss for flossers was ~1 tooth compared to ~4 teeth lost
for nonflossers. These findings further support flossing behav-
ior as an important oral hygiene habit to prevent oral disease
progression in older adults.
Author Contributions
J.T. Marchesan, contributed to data analysis and interpretation,
drafted and critically revised the manuscript; K.M. Byrd, T.
Morelli, Y. Jiao, contributed to data interpretation, critically
revised the manuscript; K. Moss, contributed to data acquisition,
analysis, and interpretation, critically revised the manuscript; J.S.
Preisser, A.F. Zandona, contributed to data analysis and interpre-
tation, critically revised the manuscript; J. Beck, contributed to
conception, design, data acquisition, and interpretation, critically
revised the manuscript. All authors gave final approval and agree
to be accountable for all aspects of the work.
Acknowledgments
The authors would like to thank Dr. Steve Offenbacher for his
mentorship and support during the development of this study. The
authors would like to thank the following support funding agency/
grant numbers—National Institutes of Health K01 DE027087-01
(JTM), K08DE026537 (KMB), K23 DE025093 (TM), and grant
R01-09060. The authors declare no potential conflicts of interest
with respect to the authorship and/or publication of this article.
ORCID iDs
K.M. Byrd https://orcid.org/0000-0002-5565-0524
J.S. Preisser https://orcid.org/0000-0002-7869-2057
J. Beck https://orcid.org/0000-0001-5415-8311
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