Abstract

Background

Chronic psychosocial stress experienced in childhood is thought to be associated with long-term health and disease risk. In particular, early life adversity (ELA)—experiences that represent a deviation from the expected environment and require adaptation, including childhood abuse, sexual assault, neglect, and chronic poverty—create risks for lifelong chronic diseases [1, 2]. Emerging evidence indicates the relationship between ELA with oral health problems [3–6]. The Japan Gerontological Evaluation Study (JAGES) reported a significant association between the experience of abuse in childhood and the reduction of residual teeth in old age. The experience of childhood abuse increased the risk of having fewer remaining teeth by 14% [4]. A cross-sectional study among Uruguayan people aged 65–74 found that the prevalence and severity of tooth loss were positively correlated with social factors such as poor socioeconomic status, use of public health services, and frequent drinking [7]. However, most previous work focused on single types of adversity, such as physical abuse [4] or poverty [5, 6].

Poor oral health, particularly edentulism, is considered a putative risk factor for frailty [7] and mortality [8]. It is a debilitating and irreversible condition and is described as the “final marker of disease burden for oral health” [9]_. As Sussex pointed out from a sociological perspective on the “epidemic of edentulism”, among older New Zealanders, edentulism is influenced by the combined effects of geography, economics, the dental care system and the professional culture, especially economic and social disadvantage [10]. The relationship between ELA and oral health conditions is well established. For example, periodontal disease (PD), the leading cause of tooth loss, is one of the most prevalent chronic inflammatory conditions in the world. Engel’s biopsychosocial model offers a more integrative theoretical orientation on how ELAs “get under the skin” to influence oral health outcomes. ELA induced consistent activation of the hypothalamic–pituitary–adrenal axis and the consequent release of the chronic stress hormone cortisol, placing a chronic burden on the body’s neuroendocrine and immune functions [11]. The latter contributes to an elevated oral inflammatory load, demonstrated as hyperactive neutrophils that are pivotal to periodontal tissue damage [12]. In addition, studies have shown that a number of ELA, such as poverty and childhood maltreatment, reflect a chronic situation and are linked to particular gene expression patterns, characterized by upregulated transcripts involved in inflammation and downregulated transcripts involved in antiviral responses (termed conserved transcriptional response to adversity; CTRA) [13]. This transcriptional pathway is believed to encourage chronic low-grade inflammation in response to stressful events, providing a mechanistic link between ELA and the emergence of inflammation-related illnesses [14]. In the context of oral health, immune systems dysregulated by ELA may increase susceptibilities to pathogenic bacteria and oral infection, potentially leading to tooth decay or periodontal diseases, one of the proximal causes of tooth loss.

Given that edentulism is relatively common in China with 4.5% of adults aged 65 to 74 years [15], the present study set out to identify ELA with indicators of edentulism among a representative population of 17,610 older adults from 450 villages/urban communities in 150 counties in 28 of China’s 30 provinces excluding Tibet across China, ad to provide an empirical basis for early prevention of edentulism and reduction of the health hazard effects of ELA.

We extended prior work by examining the relative associations of deprivation and threat as two forms of ELAs with edentulism. A recent conceptual model posits that two core underlying dimensions—threat and deprivation—encompass a wide variety of adverse experiences common in childhood [16–18]. Threat includes experiences involving harm or threat of harm, while deprivation involves an absence of expected inputs from the environment, such as cognitive and social stimulation. These dimensions cut across numerous adverse experiences that share the underlying experience of threat or deprivation to varying degrees. We hypothesized that ELA characterized by threat (i.e., physical abuse), in particular, would be associated with edentulism.

Methods

Results

Descriptive statistics for key variables are presented in Table ​Table1.1. A total of 17,610 older adults in China were included in the study. Nearly 15.9% of older adults with an average age of 63.6 years (SD=9.4, ranged 50–118 years) had lost all permanent teeth. Prevalence of edentulism was higher in older age groups, and was lower in adults who are male, married and living with the spouse, as well as those living in urban areas. Participants who experienced three or more types of threat-related ELA had a higher rate of edentulism (26.0%) than participants with no deprivation-related ELA (16.1%). Older adults who experienced three or more types of deprivation-related ELA had a higher rate of edentulism (24.0%) than participants with no deprivation-related ELA (13.6%).

Table 1

Participant characteristics

	N	%/mean (SD)	Edentulism, %		N	%/mean (SD)	Edentulism, %
Edentulism	16,868	15.9		Deprivation	15,049	1.2 (0.9)
Sociodemographic covariates				Biological mother absent	15,049	7.2	23.6¶a
Sex	17,610			1	6841	45.5	17.0¶b
Female	9200	52.2	17.3¶b	2	3430	22.8	19.3¶b
Male	8410	47.8	14.4	≥3	1455	9.7	24.0¶b
Education	17,610			Marital status	17,610
<Primary	7931	45.0	22.6¶b	Married and lived with spouse	13,700	77.8	13.5
Primary school	3597	20.4	13.6¶b	Widowed	2475	14.1	31.3¶b
Middle school	3894	22.1	8.8¶b	Others	1435	8.1	11.5
≥High school	2188	12.4	7.2	Hukou residence	17,610
Early life adversity (W1)				Rural	10,008	56.8	19.1¶b
Threat	15,323	0.9 (1.1)		Urban	7602	43.2	10.1
Unsafe community dwelling	15,323	8.5	21.7¶a	Current health conditions
Peer bullying	15,323	13.0	16.2	Hypertension	10,490	24.0	19.2¶a
Female guardian physical abuse	15,323	23.7	18.8¶a	Diabetes	10,490	5.9	16.7
Male guardian physical abuse	15,323	16.2	20.1¶a	Dyslipidemia	10,490	10.4	16.0
Sibling beat	15,323	6.2	20.5¶a	Pulmonary diseases	10,490	10.7	23.1¶a
Parental conflict	15,323	21.2	17.3§a	Heart diseases	10,490	12.0	20.51¶a
0	7628	49.8	16.1	Kidney diseases	10,490	6.7	21.9§a
1	3945	25.7	16.7	Disability	13,983	3.3	15.6
2	2168	14.1	18.7§b	Depressive symptoms	13,171	18.9	19.3¶a
≥3	1582	10.3	26.0¶b	Alcohol drinking	17,610	26.0	12.2
				Current smoke	17,610	27.0	15.1

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^aCompared with no adversity exposure group

^bCompared with the lowest group

P<0.05; ^§P<0.01; ^¶P<0.01

Associations between distinct dimensions of ELA and edentulism are presented in Table ​Table2.2. Logistic regression analysis showed threat, instead of deprivation, was associated with edentulism in Chinese adults aged 50 and older. Two types of threat-related ELA exposure were associated with 1.65-fold and 1.73-fold higher risk for edentulism in both male (95% CI 1.23, 2.21) and female participants (95% CI 1.31, 2.29) than those with no threat-related ELA exposure; three or more threat-related ELA exposure was associated with 3.15-fold and 3.37-fold higher risk for edentulism in both male (95% CI 2.34, 4.24) and female participants (95% CI 2.49, 4.56).

Table 2

The associations between distinct dimensions of early life adversity and edentulism

Early life adversity (ELA)	Adjusted odds ratio (95%CI)
	Male	Female
Threat-related ELAa
0	Ref	Ref
1	1.44 (1.12, 1.86)§	1.19 (0.95, 1.49)
2	1.65 (1.23, 2.21)¶	1.73 (1.31, 2.29)¶
≥3	3.15 (2.34, 4.24)¶	3.37 (2.49, 4.56)¶
Deprivation-related ELAb
0	Ref	Ref
1	0.85 (0.64, 1.14)	1.08 (0.83, 1.39)
2	0.82 (0.60, 1.13)	1.20 (0.90, 1.59)
≥3	0.97 (0.68, 1.39)	1.25 (0.90, 1.73)
Age	1.10 (1.09, 1.11)¶	1.09 (1.08, 1.10)¶

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^a Adjusted for age, BMI, education, household annual income, hukou residence, marital status, disease history and deprivation-related ELA

^b Adjusted for age, BMI, education, household annual income, hukou residence, marital status, disease history and threat-related ELA

P<0.05; ^§ P<0.01; ^¶ P<0.001

Discussion

The present study investigated the association of deprivation and threatening early growth adversity ELA with edentulism in this nationally representative sample of Chinese older adults and discovered that threat, but not deprivation, was associated with edentulism. High exposure to threat-related ELA was linked to edentulism in a dose–response relationship, with a significant 3.15- and 3.37-fold increase in the risk of edentulism among older men and women, respectively.

Our finding demonstrated that 15.9% of the Chinese older population reported edentulism, which is slightly higher than national studies from US and Australia. The US Centers for Disease Control and Prevention (CDC) reported that the prevalence of edentulism in people aged 65 years and older was 12.9% in 2015–2018 [20]. Data from Australian National Adult Oral Health Study 2017–2018 reported a prevalence of 8.1% of edentulism in people aged 55–74 years [21]. However, our current finding on the prevalence of edentulism is similar with data from India (16.3%) and Russia (18%) according to the World Health Organization (WHO) Study on Global Ageing and Adult Health (SAGE) Wave 1 [22]. The higher detection rate of edentulism in the Chinese elder population compared to that of the USA and Australia might be associated with patterns of infrequent preventive dental care and lower national awareness about the importance of oral health. In addition, nearly 90% of Australians have access to fluoridated drinking water, and nearly 97% of Australian children and adults brush their teeth daily with fluoride toothpaste [23]. There is consistent evidence that community water fluoridation and the widespread use of fluoride toothpaste play the most important role in preventing dental caries in Australia [24, 25]. As dental caries is considered a major cause of tooth loss [26], caries prevention reduces the risk of tooth loss.

Our study has the following advantages, First CHARLS represents the samples of the middle-aged and the elderly, through a rigorous multi-stage probability sampling procedure to select study participants, and use effective quality control, which contains a wide range of information, meet the science related to the aging problem and the need of policy research, and in harmony with the leading international research, Ensure cross-study comparability of results [19]. Second, this survey is the first to study the relationship between ELA and edentulism through two dimensions of abuse and deprivation, which is innovative.

There are several limitations in this research. First, the self-reported nature of edentulism assessment may lead to biased information. However, previous studies have shown relatively high agreement between the self-reported and clinically-assessed number of teeth in national surveys [27]. Second, the current study obtained ELA through retrospective self-report, which is inevitably subject to recall bias. Third, detailed information on the cause and duration of tooth loss, as well as periodontal diseases or oral hygiene behaviors at different life stages, is not available in the present study. Fourth, this report only stays in quantitative research and lacks qualitative research, which needs to be further supplemented in subsequent studies. Furthermore, specific clinical data on dental health status at each life stage would be useful to investigate the mechanisms whereby ELA affects dental status In older age. Despite the limitations, the current study is the first study to elucidate the relationship between distinct dimensions of ELA and edentulism using a representative sample of adults in China.

The current study found an association between threat-related ELA, instead of deprivation-related ELA, with risk of edentulism. Most previous studies regarding the relationships between threat-related ELA and edentulism focused on single forms of ELA indicators [4]. Thus this finding is an extension of previous work considering the complex and interrelated nature of co-occurring exposure to ELA-related threats. The mechanism by which threat-related ELA causes edentulism is unclear. Recent evidence shows the association between ELA involving threats (e.g., violence exposure) with accelerated biological ageing across multiple indicators [28, 29], e.g., telomere shortening. Telomere length has been associated with impaired periodontal homeostasis and the pathophysiology of periodontitis [30], and loss of periodontal attachment has also been negatively correlated with telomere length, resulting in alveolar bone resorption [31] and possibly tooth loss.

In contrast, individuals exposed to deprivation-related ELA—including those characterized by neglect, lack of primary caregivers and chronic material deprivation (food shortage)—do not tend to exhibit a high risk for edentulism that is associated with threat. This finding is consistent with the 2012 Health and Retirement Study (HRS) in the United States demonstrating childhood financial hardship was not associated with odds of edentulism in later life [32]. Changes in social and economic position throughout the course of a person's life may have a greater impact on their oral health later in life than ELA exposure associated with deprivation. In contrast, current research suggests that people who suffer deprivation are more likely to have ongoing challenges in a number of cognitive domains, including linguistic skills and executive functioning [33, 34]. Future research on the probable mechanisms by which dental care services and teeth loss are influenced by disadvantaged childhood environments would be helpful.

The present study provides support for the association between ELA with edentulism in a representative sample of the older Chinese population. ELA prevention ought to be taken into account when developing appropriate preventive measures and treatments to enhance child welfare and parent–child connections, which may eventually aid in reducing oral health disparities. By encouraging early intervention and facilitating suitable preventive treatment, policies and initiatives seeking to reduce lifetime cumulative exposures to adversities will close the oral health gap.

Conclusions

Our finding demonstrates that a specific dimension of ELA (i.e., threat but not deprivation) was associated with edentulism in the representative sample of older adults in China, provides preliminary evidence of biological aging in oral health effects of the different dimensions of ELA. Future research should clarify the biological pathways between different dimensions of ELA and increased risk of edentulism.

Acknowledgements

Abbreviations

Author contributions

All authors have made substantial contributions to conception and design of the study. SY and CX conceptualized and designed this study. SY analyzed and interpreted the data. TZQ, CX, SY, LY and HCL revised manuscript for intellectual content. All authors read and approved the final manuscript.

Funding

This work was supported by Scientific Research Projects of Anhui Medical University (for Xin Chen, Grant Number: 2020xkj145), and Disciplinary Construction Project from School of Dentistry in Anhui Medical University (for Xin Chen, Grant Number: 2021kqxKFY04). The funding provides financial support for open-access journal charges and article processing fees.

Availability of data and materials

Please contact China Health and Retirement Longitudinal Study (CHARLS) for data requests at http://charls.pku.edu.cn/.

Declarations

Footnotes

Contributor Information

Ying Sun, Email: nc.ude.umha@nusgniy.

Xin Chen, Email: moc.qq@7647925662.

References