Associations between disability type and untreated dental decay among community dwelling US adults

Abstract

Objective

Individuals with disabilities face elevated risks of adverse oral health outcomes compared with the general population, including worse periodontal health, increased edentulism, and untreated dental decay. Given the varied impacts of different disabilities on people's health and well‐being, this study aims to investigate diverse associations between untreated decay and cognitive, physical, emotional, and sensory disabilities among US adults.

Methods

This cross‐sectional study analyzed questionnaire and clinical examination data on 7084 adults (≥20 years) from the 2015–18 National Health and Nutrition Examination Survey cycles. Sociodemographics, oral health behaviors, health conditions, and disability were all examined. The prevalence of tooth decay was calculated as the proportion of adults with untreated decay. Survey‐weighted multivariable logistic regression was used to assess associations between disability and untreated decay.

Results

In general, untreated decay was more than twice as prevalent in individuals with three or more disabilities as in those without any disabilities (34.5% vs. 13.2%, p < 0.001). After adjusting for confounders, lack of functional dentition was the most significant predictor of untreated decay prevalence (adjusted odds ratio: 2.97, 95% CI: 2.37–3.72). Other significant factors were younger age (20–44), non‐Hispanic black race or ethnicity, low‐income status, having an underlying chronic condition, not having a past‐year dental visit, symptomatic dental visits, and current tobacco use.

Conclusion

No associations were found between disability type (cognitive, emotional, physical, and sensory) and untreated decay among community‐dwelling US adults. Several health‐related, social, and behavioral factors emerged as primary predictors of untreated decay. Further research is needed to explore disability types and dental caries determinants.

INTRODUCTION

The prevalence of disabilities among United States (US) adults is substantial, affecting nearly one in four individuals [1]. The International Classification of Functioning, Disability and Health (ICF) defines disability as “…an umbrella term for impairments, activity limitations and participation restrictions. It denotes the negative aspects of the interaction between an individual (with a health condition) and that individual's contextual factors (environmental and personal factors).” [2] Individuals with disabilities may encounter significant challenges in accessing adequate dental care, increasing the risk of poorer periodontal health, edentulism, untreated dental caries, and limited restorative care compared with the general population [3]. It is important to note that the oral health challenges listed are not necessarily the direct result of cognitive, emotional, physical, and/or sensory disabilities, but may be due to effects secondary to the disability. These may include reduced ability to plan, remember, cope, and/or understand; limited dexterity; and/or reliance on others for personal care, transportation, and funds. Societal and political decisions exacerbate these issues by failing to support people equitably. Social inequities, such as inadequate support systems and lack of accessible healthcare services, significantly contribute to the oral health disparities observed in this population. Barriers such as provider hesitancy, transportation or logistical difficulties in visiting dentists, insufficient follow‐up care, and increased emergency department use further worsen these disparities [4, 5]. Adopting a biopsychosocial perspective helps us understand that poor oral hygiene is not just an indirect outcome of disability but a result of complex barriers requiring comprehensive, equitable solutions.

Of paramount concern is the persisting unmet dental care need among the population with disabilities [6]. Current literature has primarily focused on individual disability types and their specific healthcare requisites, illustrating varied impacts on oral health [7, 8, 9]. A compelling need persists, however, to understand the intricate relationships among various disabilities and their collective associations with oral conditions. Moreover, just as the non‐disabled population must cope with chronic conditions such as diabetes, cardiovascular disease, and others, individuals with disabilities often contend with these same chronic conditions, but complicated in both presentation and treatment when considered in combination with their underlying disabilities [10]. These comorbidities pose additional challenges, contributing to compromised oral health through factors like poor oral hygiene, increased inflammatory load, dry mouth, cognitive and physical deficits, and overall systemic health deterioration [11].

Prior literature extensively has explored the association between individual disability categories and their specific oral health outcomes among adults [7, 8, 9]. Notably, developmental disabilities, cognitive impairments, emotional disabilities, physical limitations, and sensory impairments exhibit unique patterns in their impact on oral health. For example, studies have found links between developmental disabilities like cerebral palsy, Down syndrome, and intellectual deficits, and elevated oral health risks, including higher rates of untreated caries, pronounced periodontal diseases ³ , heightened caries rates and inadequate oral hygiene [12]. Cognitive disabilities, such as memory loss, exhibited links between self‐care abilities and impaired oral hygiene [7] while an association between impaired delayed memory and a serological marker of periodontitis was found by Noble et al. [8] In addition, emotional disabilities, such as depression and anxiety, were positively correlated with tooth decay, tooth loss, and mild periodontitis, which were attributed to factors like poor oral hygiene, smoking habits [13], diet, and effects of psychiatric medications, such as changes in the amount and consistency of saliva [14].

Physical disabilities, defined as experiencing limitations in activities of daily living, are associated with self‐rated poor oral health, gum diseases, and tooth loss, often linked to diminished self‐care abilities and functional independence [9]. People with sensory disabilities, including visual and hearing impairments, also present with a variety of poorer oral health outcomes. Studies revealed inadequate oral hygiene practices, disparities in availability of dental resources among individuals with visual impairment [15], suboptimal oral hygiene attributed to socioeconomic factors [16], and poor oral health‐related quality of life (OHRQoL) among those with hearing impairment [17].

While the literature has focused on individual disability types, research exploring the relationship among concurrent impairments and oral health is limited. Study findings by Lee et al. [18] indicated that individuals with any disability exhibit more dental issues, such as caries, tooth loss, and fewer restorations, compared with those without disabilities, emphasizing the need for comprehensive analyses distinguishing among disability types.

In light of the gaps in the current literature, the rationale of this study is to provide a comprehensive analysis of various disability types and their associations with oral health, particularly untreated dental decay. This study bridges existing knowledge gaps by using nationally representative population‐based data to provide insights useful to public health programs that target oral health disparities among people with disabilities.

Notably, because of National Health and Nutrition Examination Survey (NHANES) recruitment methods, this study only includes non‐institutionalized individuals who are well enough to participate in a lengthy interview and dental exam. In general, this requirement excludes individuals with the most severe disabilities, those who are institutionalized, and those who lack capacity to provide informed consent or participate in the survey independently.

METHODS

Study design

To conceptualize potential relationships between various kinds of disabilities and the study outcome of untreated dental decay, a theoretical framework was developed based on the existing literature and the context of the NHANES disability and oral health data (Figure 1). Central to this framework are oral health‐related behaviors as primary risk factors for untreated dental decay, in addition to other health‐related factors such as sociodemographics, underlying chronic conditions, and prolonged medication use inducing dry mouth. This framework does not encompass downstream factors such as oral biology, and upstream determinants like social influences, healthcare system, or political factors affecting oral health, due to data limitations.

FIGURE 1.

A conceptual framework illustrating potential links between disability and untreated dental decay. [Color figure can be viewed at wileyonlinelibrary.com]

A cross‐sectional analysis was conducted using data from the NHANES to explore the associations between various disabilities and untreated dental decay. The analysis utilized two NHANES cycles: 2015–2016 and 2017–2018, excluding subsequent cycles due to lack of similar methodology (i.e., lack of identical oral health‐related and disability questions, etc.). NHANES is conducted by the National Center for Health Statistics (NCHS) and employs a stratified, multistage, clustered sampling design to obtain a nationally representative sample of noninstitutionalized, civilian residents of all ages. The survey includes clinical examinations, selected medical and laboratory tests, and self‐reported data through in‐home personal interviews and physical examinations in a mobile examination center.

In order to ensure adequate sample size for subgroup analyses, NHANES oversamples certain groups, such as Hispanics, non‐Hispanic Blacks, non‐Hispanic, non‐Black Asians, low‐income white, individuals at or below 185% of federal poverty level, children aged 0–11, and adults aged 80 and over. Individual and survey weights were employed to enable generalization of results to the entire US population. Detailed NHANES sampling methodology documentation is available online [19, 20].

This analysis included 7084 adults aged 20 or older who completed both the personal interview and dental examination, without missing data in the 2 cycles (Figure 2). In terms of data management, all variables were converted into categorical variables, as described in Data S1.

FIGURE 2.

A flowchart illustrating how the sample size was derived from NHANES cycles 2015–16 and 2017–18. [Color figure can be viewed at wileyonlinelibrary.com]

Outcome (dependent) variable

The primary outcome of the study is untreated dental decay. For the 2015–18 cycles, NHANES dentist examiners received extensive training and calibration sessions, with ongoing monitoring (including random repeated examinations) and recalibration, to ensure consistent and high‐quality oral health data [21]. Typically, NHANES cycles exhibit high kappa scores, suggesting excellent reliability and reproducibility. For instance, kappa scores for untreated dental caries in NHANES 2011–14 ranged from 0.93 to 1.00 [22]. NHANES records dental examination results for permanent teeth, assigning a specific variable to each tooth. A tooth is categorized as decayed if it was coded as ‘J' (permanent root tip present, but no restorative replacement) or ‘Z' (permanent tooth with unrestored dental carious surface condition). Therefore, the binary outcome variable, untreated dental decay, was assigned if the participant had any decayed teeth (excluding third molars), that received either a ‘J' or ‘Z' code.

Main explanatory (independent) variables

Independent variables include disabilities and oral health behaviors. A 12‐item disability questionnaire (DLQ‐I) from NHANES, provided by the Disability and Health Branch at CDC, was administered to assess function and activity limitations among NHANES study participants. For this study, we use the term “disability” to encompass a range of related concepts such as impairments and functional limitations. While we recognize that the ICF differentiates these terms, “disability” is the term used in NHANES and serves as a national benchmark, facilitating comparisons with other studies. Therefore, it is applied to refer to all similar concepts, with distinctions emphasized.

Disabilities

Cognitive disabilities are defined as having mental health disorders that primarily affect learning, memory, perception, and problem solving [23]. Cognitive disabilities were assessed through one item that assessed participant's self‐reported responses to questions regarding difficulty concentrating, remembering, or making decisions.

Emotional disabilities are defined as having persistent emotional or behavioral responses that adversely affect performance in the educational, workplace, and home environment that cannot be explained by intellectual, sensory, or health factors [24]. Four items assessed emotional disabilities by participants' reporting of frequency and severity of anxiety and depression symptoms.

Physical disabilities are defined as “limitations on a person's physical functioning, mobility, dexterity, or stamina [25] due to impairments of physical structure or function.” Physical disabilities were examined using two items: Mobility was assessed through questions regarding difficulty walking or climbing stairs. Self‐care was assessed through one question regarding difficulty dressing or bathing.

Sensory disabilities are defined as a deficit of one or more senses; sight, hearing, smell, touch, taste, or spatial awareness [26]. In this study, sensory disabilities were assessed using two items assessing respondents' difficulty hearing and seeing.

The total number of disabilities was also assessed for each participant. Seven disabilities (cognitive disability, severe anxiety, severe depression, physical disability including mobility and self‐care disability, and difficulty seeing and hearing) were considered. Frequent anxiety and depression were excluded from this variable because they are highly correlated with severe anxiety and severe depression. Responses were categorized as no disabilities, one disability, two disabilities, and three or more disabilities.

Functional dentition

A functional dentition was assessed based on the number of opposing teeth (i.e., functional units present). It is defined as “having a minimum of 20 teeth with 6 posterior functional units, which is associated with adequate chewing efficiency and ability.” [27] For this study, a functional dentition included all participants with 6 or more opposing pairs of posterior teeth, while a lack of functional dentition included those having fewer than 6 opposing pairs of posterior teeth.

Oral health behaviors

The four self‐reported oral health‐related behaviors assessed by the NHANES questionnaire were included in this study: diet, flossing, dental care utilization, and tobacco use. Alcohol use was first considered but was dropped because of a high percentage of missing responses. Diet was assessed through participants' rating of their diet on a Likert scale from poor to excellent. Excellent, very good, and good responses were combined to denote a healthy diet. Frequency of flossing or use of inter‐dental devices during the previous 7 days was assessed on a continuous scale from zero to seven. Flossers included those who flossed for 2 days or more in the past 7 days. Dental care utilization was assessed in two areas; time since last dental visit (in the past year vs. more than a year ago) and reason for the visit (routine vs. symptomatic care or treatment). Current tobacco use was assessed on a binary scale regarding whether participants had used any combustible tobacco product in the last 5 days.

Covariates

In addition to assessing the number and types of chronic conditions, other covariates included prescribed medication use (number of prescriptions and medication type, namely, dry mouth inducing vs. not), and socio‐demographic characteristics of age, sex, race/ethnicity, income‐level, education‐level, marital status, and military status. All variables were categorized for analysis.

Statistical analysis

The Statistical Analysis System (SAS), version 9.4, was used for all analyses. Significance level was set at 5% (p < 0.05). Because of NHANES' complex sampling strategy and the unequal probability for participant selection, all analyses included individual, stratum, and cluster weights. Data analysis consisted of descriptive statistics with frequency distributions and bivariate regression for disability variables and covariates by the presence or absence of untreated dental decay. Inferential statistics, including multivariable logistic regression, was conducted to identify the factors associated with untreated dental decay. Initially, for logistic regression, a stepwise model selection was conducted on unweighted data. Subsequently, weights were incorporated to develop the final adjusted model, addressing survey design complexities and enhancing the model's precision. p‐values together with the 95% confidence intervals for the odds ratios were reported from the adjusted model.

RESULTS

Socio‐demographic and health‐related characteristics

The study encompassed 7084 participants, with an average and median age of 50.5 and 51, respectively. The sample population was primarily aged 45–64 years (44.2%) and predominantly female (52.2%) and non‐Hispanic White (68%). Nearly 20.4% were categorized as low income as described by the federal poverty guideline income limit, while 11.8% had not completed high school.

Nearly a third of the sample (29%) reported having any single type of disability, while more than half (52%) had at least one disability. From most to least reported function or activity limitations were difficulty walking or climbing (13.8%); serious difficulty concentrating, remembering, or making decisions (9.6%); serious difficulty hearing (9.5%); severe anxiety (9%) and severe depression (7.3%); serious difficulty seeing (5.3%); and difficulty dressing or bathing (4.7%). Almost half of the participants reported multimorbidity (46.7%), indicating multiple chronic conditions and use of multiple prescription medications (48.5%). Regarding health behaviors, a majority reported healthy diets (71%) and flossing more than once a week, with over half having a dental visit within the past year for routine care. A considerable portion (22%), however, were current smokers. Untreated dental decay prevalence, defined as having at least one tooth with untreated caries, stood at 22.4% (Table 1).

TABLE 1.

Descriptive statistics of socio‐demographic and health‐related characteristics of US adults, NHANES 2015–2018 (n = 7084).

Demographics / socioeconomic risk factors:	Weighted* n (%, SE)
Age
20–44	49,423,120 (30.9, 1.3)
45–64	70,716,436 (44.2, 1.0)
65–74	24,994,283 (15.6, 0.9)
75+	14,777,591 (9.2, 0.6)
Sex
Male	76,441,349 (47.8, 0.6)
Female	83,470,081 (52.2, 0.6)
Race/ethnicity
Hispanic	20,584,530 (12.9, 1.5)
Non‐Hispanic White	108,806,251 (68.0, 2.4)
Non‐Hispanic Black	15,901,183 (9.9, 1.3)
Other race, including multi‐racial	14,619,465 (9.1, 0.9)
Income level
Low	32,604,638 (20.4, 1.1)
Middle	19,129,759 (12.0, 0.6)
High	108,177,032 (67.6, 1.5)
Education level
No high school degree	18,840,671 (11.8, 0.9)
High school degree	141,070,759 (88.2, 0.9)
Marital status [4]
Not in a relationship	50,489,411 (31.6, 1.3)
In a relationship	109,422,018 (68.4, 1.3)
Military status
No	142,098,081 (88.9, 0.7)
Yes	17,813,348 (11.1)
Disabilities:
Cognitive disability (Have serious difficulty concentrating?)
No	144,603,476 (90.4, 0.6)
Yes	15,307,953 (9.6, 0.6)
Emotional disability
Frequency of anxiety (How often do you feel worried, anxious?)
Experience no anxiety symptoms	31,635,489 (19.8, 0.7)
Experience anxiety symptoms	128,275,940 (80.2, 0.7)
Severity of anxiety (How worried or anxious were you?)
Never	31,635,489 (19.8, 0.7)
Non‐severe anxiety	113,858,900 (71.2, 0.8)
Severe anxiety	14,417,041 (9.0, 0.6)
Frequency of feeling depressed (How often do you feel depressed?)
Experience no depression feelings	73,123,658 (45.7, 1.1)
Experience depression feelings	86,787,772 (54.3, 1.1)
Severity of depression (How depressed did you feel?)
Never	73,123,658 (45.7, 1.1)
Non‐severe depression	75,099,473 (47.0, 1.0)
Severe depression	11,688,300 (7.3, 0.5)
Physical disability
Mobility (Have serious difficulty walking or climbing stairs?)
No	137,892,527 (86.2, 0.9)
Yes	22,018,902 (13.8, 0.9)
Self‐care (Difficulty dressing or bathing)
No	152,387,289 (95.3, 0.4)
Yes	7,524,141 (4.7, 0.4)
Functional dentition (Having 6 or more opposing posterior teeth i.e., functional units)
Functional dentition	101,631,056 (63.6, 1.5)
Lack of functional dentition	58,242,365 (36.4, 1.5)
Sensory disability
(Have serious difficulty seeing?)
No	151,510,753 (94.7, 0.4)
Yes	8,400,677 (5.3, 0.4)
(Have serious difficulty hearing?)
No	144,723,443 (90.5, 0.6)
Yes	15,187,987 (9.5, 0.6)
Number of disabilities
No disabilities	76,826,985 (48.1, 1.5)
One disability	46,326,389 (29.0, 0.8)
Two disabilities	18,746,066 (11.7, 0.6)
Three or more disabilities	17,973,981 (11.3, 0.8)
Chronic conditions*
No chronic condition	42,351,159 (26.5, 0.9)
One chronic condition	42,842,996 (26.8, 0.8)
Multimorbidity (more than one condition)	74,717,275 (46.7, 1.2)
Medications
Medicine Count
No prescription medications	55,422,633 (34.7, 1.1)
One prescription medication	26,911,687 (16.8, 0.7)
More than one prescription medication	77,577,110 (48.5, 1.1)
Medicine type
No dry mouth inducing medications	108,180,271 (67.6, 0.9)
Dry mouth inducing medications	51,731,159 (32.3, 0.9)
Healthiness of the diet (How healthy is your diet)
Unhealthy diet	46,357,073 (29.0, 1.0)
Healthy diet	113,554,357 (71.0, 1.0)
Dental Flossing (How many days use dental floss/device)
Non‐flossers	54,682,376 (34.2, 1.2)
Flossers	105,229,053 (65.8, 1.2)
Dental care utilization
Time since last dental visit (When did you last visit a dentist)
Last dental visit more than a year ago	61,683,362 (38.6, 1.5)
Last dental visit in the past year	98,228,067 (61.4, 1.5)
Reason for visiting the dentist (Main reason for last dental visit)
Symptomatic care and treatment	59,787,163 (37.4, 1.6)
Routine care	100,124,267 (62.6, 1.6)
Current tobacco use
Non‐current tobacco users	124,670,974 (78.0, 1.0)
Current tobacco users	35,240,455 (22.0, 1.0)
Prevalence of untreated tooth decay	35,798,844 (22.4%)

Abbreviation: SE, standard error.

^*A summary score was calculated to sum up the number of conditions each participant has (out of 20 chronic conditions: asthma, diabetes, hay fever, anemia, body mass index (BMI)/obesity, blood transfusion, arthritis, gout, congestive heart failure, coronary heart disease, angina, heart attack, stroke, emphysema, thyroid problem, chronic bronchitis, liver condition, COPD, jaundice, and cancer).

Untreated dental decay by socio‐demographic characteristics, disability status, chronic conditions, medicinal use, and oral health behaviors

Though caries experience (total number of decayed, missing and filled teeth) always increases with age, in our study, the proportion of untreated decay decreased with age but was higher among non‐Hispanic Blacks (36.8%) and Hispanics (26.8%) compared with Whites (19.7%). Higher rates of untreated decay were also associated with not being in a relationship, and having lower income or education. Untreated tooth decay was significantly associated with difficulty concentrating (p < 0.0001), frequent depression symptoms (p = 0.04), severe anxiety (p = 0.0003) and depression (p = 0.0016), difficulty walking or climbing stairs (p < 0.0001), difficulty dressing or bathing (p < 0.0001), lack of functional dentition (p < 0.0001), and difficulty seeing (p < 0.0001). Individuals with three or more disabilities had 3.5 times higher odds of having untreated dental decay than individuals with no disabilities. Individuals taking medications showed a lower likelihood of untreated decay. Oral health behaviors such as a healthy diet, flossing, last dental visit in the past year, and not seeking dental care for symptoms or treatment were negatively associated with untreated decay, while current smoking exhibited a positive association (Table 2).

TABLE 2.

Univariate Logistic Regression Analysis of factors associated with untreated dental decay in permanent teeth (decayed teeth [DT] ≥1) among adults aged ≥20, United States, National Health and Nutrition Examination Survey, 2015–2018 (n = 7084).

Prevalence of untreated tooth decay in permanent teeth among US adults‐NHANES 2015–2018 (weighted data)
Variable	No untreated tooth decay present n (%)	Untreated tooth decay present n (%)	Unadjusted OR (95% CI)	p‐value
Demographics/socioeconomic risk factors
Age (years)				<0.0001
20–44	74.6	25.4	2.1 (1.7–2.8)	<0.0001
45–64	76.2	23.8	1.9 (1.5–2.6)	<0.0001
65–74	82.4	17.6	1.3 (1.0–1.9)	0.07
75+(ref)	86.3	13.7	1.0	***
Sex				<0.0001
Female (ref)	80.0	20.0	1.0	***
Male	75.1	24.9	1.3 (1.1–1.5)	0.0006
Race/ethnicity				<0.0001
Non‐Hispanic White (ref)	80.3	19.7	1.0	***
Hispanic	73.2	26.8	1.5 (1.1–2.0)	0.0067
Non‐Hispanic Black	63.2	36.8	2.4 (1.9–3.0)	<0.0001
Other race, including multi‐racial	79.7	20.3	1.0 (0.8–1.3)	0.76
Income level				<0.0001
Low (ref)	62.0	38.0	1.0	***
Middle	70.8	29.2	0.7 (0.6–0.8)	<0.0001
High	83.5	16.5	0.3 (0.3–0.4)	<0.0001
Education level				<0.0001
No high school degree (ref)	65.5	34.5	1.0	***
High school degree	79.2	20.7	0.5 (0.4–0.6)	<0.0001
Marital status				<0.0001
Not in a relationship (ref)	71.6	28.4	1.0	***
In a relationship	80.4	19.6	0.6 (0.5–0.7)	<0.0001
Military Status				0.59
No (ref)	77.7	22.3	1.0	***
Yes	76.8	23.2	1.1 (0.9–1.3)	0.59
Disabilities
Cognitive disability (have serious difficulty concentrating?)				<0.0001
No (ref)	78.6	21.4	1.0	***
Yes	68.2	31.8	1.7 (1.4–2.1)	<0.0001
Emotional disability
Frequency of anxiety (how often do you feel worried, anxious?)				0.73
Experience no anxiety symptoms (ref)	78.1	21.9	1.0	***
Experience anxiety symptoms	77.5	22.5	1.0 (0.8–1.3)	0.73
Severity of anxiety (how worried or anxious were you?)				0.0003
Never (ref)	78.1	21.9	1.0	***
Non‐severe anxiety	78.7	21.2	1.0 (0.8–1.2)	0.71
Severe anxiety	67.4	32.6	1.7 (1.3–2.3)	0.0006
Frequency of feeling depressed (how often do you feel depressed?)				0.04
Experience no depression feelings (ref)	79.5	20.5	1.0	***
Experience depression feelings	76.0	24.0	1.2 (1.0–1.5)	0.04
Severity of depression (how depressed did you feel?)				0.0016
Never (ref)	79.5	20.5	1.0	***
Non‐severe depression	77.4	22.6	1.1 (1.0–1.4)	0.18
Severe depression	67.0	33.0	1.9 (1.4–2.7)	0.0004
Physical disability
Mobility (have serious difficulty walking or climbing stairs?)				<0.0001
No (ref)	78.9	21.1	1.0	***
Yes	69.3	30.7	1.7 (1.4–2.0)	<0.0001
Self‐care (difficulty dressing or bathing)				<0.0001
No (ref)	78.0	22.0	1.0	***
Yes	69.2	30.8	1.6 (1.3–1.9)	<0.0001
Functional dentition (having 6 or more opposing posterior teeth i.e., functional units)				<0.0001
Functional dentition (ref)	85.3	14.6	1.0	***
Lack of functional dentition	64.1	35.8	3.3 (2.7–3.9)	<0.0001
Sensory disability
(Have serious difficulty seeing?)				<0.0001
No (ref)	78.3	21.7	1.0	***
Yes	65.1	35.0	1.9 (1.5–2.6)	0.0001
(Have serious difficulty hearing?)				0.45
No (ref)	77.8	22.2	1.0	***
Yes	75.9	24.1	1.1 (0.8–1.5)	0.45
Number of disabilities				<0.0001
No disabilities (ref)	86.8	13.2	1.0	***
One disability	70.3	29.7	2.8 (2.3–3.4)	<0.0001
Two disabilities	69.4	30.6	2.9 (2.2–3.4)	<0.0001
Three or more disabilities	65.5	34.5	3.5 (2.8–4.3)	<0.0001
Chronic conditions				0.35
No chronic condition (ref)	77.2	22.8	1.0	***
One chronic condition	76.2	23.8	1.1 (0.9–1.3)	0.58
Multimorbidity (more than one condition)	78.7	21.3	0.9 (0.7–1.1)	0.41
Medications
Medicine Count				<0.0001
No prescription medications (ref)	72.7	27.3	1.0	***
One prescription medication	80.2	19.8	0.7 (0.5–0.9)	0.0037
More than one prescription medication	80.2	19.8	0.7 (0.6–0.8)	<0.0001
Medicine type				0.21
No dry mouth inducing medications (ref)	77.0	23.0	1.0	***
Dry mouth inducing medications	78.9	21.1	0.9 (0.7–1.1)	0.21
Healthiness of the diet [2] (how healthy is your diet)				<0.0001
Unhealthy diet (ref)	71.9	28.1	1.0	***
Healthy diet	79.9	20.1	0.6 (0.5–0.8)	<0.0001
Dental flossing (how many days use dental floss/device)				<0.0001
Non‐flossers (ref)	72.9	27.1	1.0	***
Flossers	80.0	20.0	0.7 (0.6–0.8)	<0.0001
Dental care utilization
Time since last dental visit (when did you last visit a dentist)				<0.0001
Last dental visit more than a year ago (ref)	63.4	36.5	1.0	***
Last dental visit in the past year	86.5	13.5	0.3 (0.2–0.3)	<0.0001
Reason for visiting the dentist [5] (main reason for last dental visit)				<0.0001
Symptomatic care and treatment (ref)	64.0	36.0	1.0	***
Routine care	85.7	14.3	0.3 (0.3–0.3)	<0.0001
Current tobacco use				<0.0001
Non‐current tobacco users (ref)	82.4	17.6	1.0	***
Current tobacco users	60.8	39.2	3.0 (2.6–3.5)	<0.0001
Total: % (# million)	77.6 (124.1)	22.4 (35.8)

Note: Bivariate logistic regression was used to examine the association between each covariate and untreated dental decay. For each covariate, p‐values for the comparisons between each category and the reference category were provided following the p‐value for the overall covariate effect. *** denotes that the OR is 1.00 for the reference group.

Factors associated with untreated dental decay

After adjusting for potential confounders, those adults with a lack of functional dentition exhibited increased odds of untreated decay (adjusted odds ratio [aOR]: 2.97, 95% CI: 2.37–3.72) compared with those with a functional dentition. Other factors among this sample that were protective against untreated dental decay were high‐income (aOR 0.64, 95% CI = 0.55–0.74; p = <0.0001), past year dental visit (aOR 0.41, 95% CI = 0.33–0.51; p = <0.0001), routine dental visit (aOR 0.55, 95% CI = 0.47–0.65; p = <0.0001), and more than one prescription medication (aOR 0.74, 95% CI = 0.61–0.90; p = 0.01). Other significant predictors of untreated dental decay were age (untreated decay decreases as age increases at all ordinal age levels), non‐Hispanic Black race (aOR = 1.57, 95% CI = 1.26–1.95; p = 0.0002), one underlying chronic condition (aOR = 1.25, 95% CI = 1.02–1.54; p = 0.01), and current tobacco use (aOR = 1.72, 95% CI = 1.44–2.05; p = <0.0001) (Table 3).

TABLE 3.

Multivariable Logistic Regression of factors significantly associated with untreated dental decay among adults aged ≥20, United States, National Health and Nutrition Examination Survey, 2015–2018 (N = 7084).

Characteristic	Had untreated dental decay, aOR (95% CI)	p‐value
Age		0.0024
20–44	3.09 (2.07, 4.61)	<0.0001
44–64	2.42 (1.62, 3.16)	<0.0001
65–74	1.65 (1.21, 2.26)	0.0024
75+(ref)	***	***
Race/ethnicity		0.0002
Hispanic	1.11 (0.84,1.47)	0.44
Non‐Hispanic White (ref)	***	***
Non‐Hispanic Black	1.57 (1.26, 1.95)	0.0002
Other race, including multi‐racial	0.89 (0.68, 1.11)	0.26
Income level		<0.0001
Low (ref)	***	***
Middle	0.85 (0.71, 1.03)	0.11
High	0.64 (0.55, 0.74)	<0.0001
Functional dentition (having 6 or more opposing posterior teeth i.e., functional units)		<0.0001
Functional dentition	***	***
Lack of functional dentition	2.97 (2.37, 3.72)	<0.0001
Chronic conditions		0.04
No chronic condition (ref)	***	***
One chronic condition	1.25 (1.02, 1.54)	0.04
Multimorbidity (more than one condition)	1.00 (0.77, 1.29)	0.98
Medication Count		0.0042
No prescription medications (ref)	***	***
One prescription medication	0.80 (0.60, 1.07)	0.12
More than one prescription medication	0.74 (0.61, 0.90)	0.0042
Time since last dental visit (when did you last visit a dentist)		<0.0001
Last dental visit more than a year ago (ref)	***	***
Last dental visit in the past year	0.41 (0.33–0.51)	<0.0001
Reason for visiting the dentist (main reason for last dental visit)		<0.0001
Symptomatic care and treatment (ref)	***	***
Routine care	0.55 (0.47–0.65)	<0.0001
Current tobacco use		<0.0001
Non‐current tobacco users (ref)	***	***
Current tobacco users	1.72 (1.44, 2.05)	<0.0001

Note: Survey logistic regression (proc surveylogistic in SAS) was used to fit the selected final model. For each covariate, p‐values for the comparisons between each category and the reference category were provided following the p‐value for the overall covariate effect. *** denotes that the OR is 1.00 for the reference group.

DISCUSSION

To our knowledge, this is the first study to examine the association between disability types and untreated dental decay in community‐dwelling adults using representative national data. This cross‐sectional analysis utilized NHANES data from 2015 to 2018, involving adults aged 20 years and older. In total, 22.4% of our sample had untreated decay, slightly lower than reported from NHANES 2016 data, suggesting continued decreases in untreated decay among US adults [28]. Our data aligns closely with national disability prevalence rates reported by use of the 2019 Behavioral Risk Factor Surveillance System (BRFSS) [29].

Most disability types examined showed associations with untreated decay in the univariate analyses, but these associations disappeared after adjusting for potential confounders. Several health‐related, social, and behavioral factors—particularly lack of functional dentition—were associated with having untreated decay. Adults lacking functional dentition were almost three times more likely to have untreated decay versus their counterparts. Considering the potential social desirability bias in self‐reported oral health practices like diet and flossing, the absence of a sufficient number of teeth to function may be the most reliable sign of poor individual oral health practices. It could also indicate that individuals are unable to eat healthier foods and instead turn to consuming readily available, soft, or unhealthy foods.

Our findings on sociodemographic factors (age, race, and income) corroborate previous NHANES and other studies' results ([13, 28, 30]). Although our study revealed a correlation between untreated decay and chronic diseases, this relationship was significant only for single conditions, not for multiple conditions. Nonetheless, other researchers [8] found an association between chronic conditions and unmet dental care needs, including untreated dental decay in adults with asthma [31]. Weakened immune systems from chronic conditions may hinder oral infection resistance [8]. Managing complex health demands often requires medications that may compromise oral health by reducing the amount and character of saliva, and the necessity to prioritize primary healthcare over dental care, leading to delayed dental visits. In this respect, adults who had routine dental check‐ups within the past year had lower odds of untreated decay than those who sought symptomatic care or treatment, or had their last dental visit more than a year ago. Conversely, tobacco use was positively correlated with tooth decay, underscoring the adverse effects of nicotine and related tobacco combustion products on saliva, the immune system, and oral tissues.

Flossing showed a negative correlation with untreated decay in the bivariate analysis, despite the lack of significance as a caries predictor in the regression analysis. Previous research on flossing's effectiveness against tooth decay in children and adults is inconsistent and limited [31], but shows effectiveness in reducing gingivitis when coupled with brushing [32]. The use of multiple medications was negatively associated with untreated decay, suggesting a complex interaction among age, chronic conditions, and medication use, as explored by Dwyer et al. [33] Unexpectedly, individuals not using prescription medications showed higher odds of untreated decay, warranting further exploration. This finding may be influenced by medication types, their dosages and specific side effects, or presence of one or more underlying undiagnosed or untreated chronic conditions.

Our findings that disabilities were not associated with dental caries were both convergent and divergent from the literature. For instance, Aldosari et al. [13] found that depression was associated with periodontal disease and missing teeth but not with untreated decay among adults. In contrast, a Hungarian study [34] reported poorer oral health among physically disabled patients, marked by frequent dental caries and missing teeth.

Disabilities can indirectly contribute to dental caries by impairing an individual's ability to maintain a healthy diet, practice good oral hygiene, and access dental care, with changes in oral biology, including reduced saliva production, often compounding these challenges. Oral hygiene and dental care mainly address existing problems rather than preventing them, so understanding caries prevention in individuals with disabilities must also consider dietary habits and saliva production. Additionally, research has linked the oral health impacts of disabilities to risk factors like poor dental hygiene, unhealthy diets, smoking, and side effects of psychotropic medications [13, 14]. Lack of functional independence and self‐care difficulties further exacerbate disability challenges [34]. Societal and systemic factors, including income, race, and the accessibility, affordability, and availability of dental healthcare services, also compound the risk of untreated dental caries within disabled populations [35].

A major strength of this study is the use of NHANES, which serves as a large and representative data set of the American population. NHANES also employs comprehensive standardized dental examinations that were designed to reduce examiner errors and increase the reliability of the data. Additionally, this study is the first of its kind to capture data regarding an array of disabilities, including psychological, physical, and sensory. Addressing health‐related needs among this population should go beyond the boundaries of a specific medical condition and should capture various functional, emotional, and informational need aspects. Even though access to care and behavior change continues to be a top priority in the healthcare industry, attention should be paid to holistic care models that identify patients who have difficulties with activities of daily living, self‐care, and seeking preventive and restorative dental care.

There are a few limitations to this study. Cross‐sectional data from data sources like NHANES is appropriate for assessing associations, but it cannot be used to infer causality. Additionally, much of the information regarding covariates (demographics, income, preventive care practices, smoking status, etc.) is self‐reported interview data that is subject to recall and social desirability bias. The limitations of the NHANES questionnaire means that important dental caries risk factors must be inferred or determined from other information. For example, biological factors such as xerostomia (which was indirectly inferred from reported medications), the oral microbiome, and malocclusion, as well as behavioral factors such as tooth brushing, may have been a more valid indicator of oral hygiene than flossing. NHANES is designed for surveillance purposes, specifically caries measures (decayed, missing, and filled teeth in this case), which are limited in their validity due to uncertainties regarding whether a tooth was lost due to decay or for another reason. Lastly, although NHANES is designed to capture a representative sample of the US population, it excludes institutionalized individuals and those who lack capacity to give informed consent or participate independently, limiting its generalizability. This is especially important for this analysis because severe disabilities and chronic conditions are more prevalent in institutionalized populations, which our sample does not include. Therefore, our results should be interpreted with caution.

IMPLICATIONS FOR FUTURE RESEARCH

The study results highlight the intricate nature of oral health in non‐institutionalized populations with disabilities. Further research should explore how intraoral cameras can be used to assess oral health status of institutionalized individuals with complex disabilities. These cameras provide rapid, high‐quality imaging that can be evaluated remotely, enabling thorough examinations and early problem detection without the need for patients or dentist examiners to travel. Images could be scored by a panel of trained and calibrated examiners anywhere there is an internet connection. This technology could particularly benefit those with severe disabilities who struggle to access traditional dental care. Future studies should evaluate the effectiveness of intraoral imaging techniques in institutional settings, and their potential to improve surveillance and reduce healthcare disparities in this vulnerable and difficult‐to‐reach population. Studies should also collect quality information on oral health practices, dental care availability, types and dosages of medications, and how disability may impact individual daily lives and their interaction with the healthcare system.

CONCLUSION

After adjusting for confounders, the associations between each disability type (cognitive, emotional, physical, and sensory) and untreated decay were no longer significant. Instead, several health‐related, social, and behavioral factors emerged as primary predictors of untreated decay among community dwelling US adults. Continued research is warranted to understand the relationships between various disabilities and the social and behavioral determinants of dental caries.

FUNDING INFORMATION

This research was supported by the National Institutes of Health (NIH), and National Institute of Dental, Oral and Craniofacial Research (NIDCR). The authors received compensation, either in the form of a stipend or salary, from the NIH during their involvement in the project.

CONFLICT OF INTEREST STATEMENT

The authors declare no conflict of interest.

INFORMED CONSENT

Informed consent of all survey participants was received through NHANES prior to their involvement in the surveys.

Supporting information

DATA S1. Supporting Information.

Biographies

Ishita Singh is a Dental Public Health Research Fellow at the National Institute of Dental, Oral and Craniofacial Research (NIDCR) at National Institutes of Health (NIH).

Xiaobai Li is a statistician at the Biostatistics and Clinical Epidemiology Unit, Office of Director, Clinical Research Center, National Institutes of Health (NIH)

Timothy J. Iafolla is Chief of the Program Analysis and Reports Branch and a Supervisory Science Policy Analyst at the Office of Science Policy and Analysis, National Institute of Dental, Oral and Craniofacial Research (NIDCR), National Institutes of Health (NIH).

Shahdokht Boroumand is a Dental Public Health Consultant for the Dental Public Health and Research Fellowship within the Office of Science Policy and Analysis, National Institute of Dental, Oral and Craniofacial Research (NIDCR), National Institutes of Health (NIH).

Hosam Alraqiq is a Health Science Analyst and Director of the Dental Public Health and Research Fellowship within the Office of Science Policy and Analysis, National Institute of Dental, Oral and Craniofacial Research (NIDCR), National Institutes of Health (NIH).

Singh I, Li X, Iafolla TJ, Boroumand S, Alraqiq H. Associations between disability type and untreated dental decay among community dwelling US adults. J Public Health Dent. 2024;84(4):439–452. 10.1111/jphd.12644