1.Background

As the global elderly population increases, interest in healthy aging is increasing. Physical disabilities in the elderly make it difficult to access dental care, and inac-tivity creates financial barriers to dental care. And taking medications for chronic diseases causes dry mouth and oral diseases¹⁾. Health and oral health influence each other. Therefore, maintaining oral health is important in order to age well.

The experience of oral problems increases with age. Dental caries, periodontal disease, dry mouth, and oral cancer contribute to tooth loss. And tooth loss increases temporomandibular joint symptoms in older adults²⁾. Also pain-free chewing is important for maintaining general health as it relates to food selection and nutritional intake³⁾. When masticatory function is reduced, cognitive function and mental health are also affected⁴⁾. Therefore, main-taining teeth can delay oral frailty.

Recently, the rate of tooth loss has been decreasing. However, poor oral care and the prevalence of oral disea-ses are still high⁵⁾. Therefore, preventive management of oral frailty is necessary for aging well.

The rate of oral frailty varies from person to person. Factors such as number of retained teeth, number of func-tional teeth, and oral muscle strength play a role⁶⁾. Main-taining 20 teeth is important for successful oral frailty⁷⁾, Maintaining a nutritious diet is important to avoid decrea-sed salivary gland function, wound healing ability, and sarcopenia⁸⁾. Additionally, the oral cavity is responsible for digestive functions, and the microbiome increases dige-stive ability and is involved in regulating immune system function. Therefore, oral health also affects metabolism and regenerative capacity in old age⁹⁾.

The effects of oral diseases and systemic diseases have been presented in various studies. Tooth loss and diabetes accelerate cognitive decline in old age¹⁰⁾, and Stress from dental treatment in patients with high blood pressure and orthostatic hypotension, and cough reflex in patients with lung disease are factors that avoid treatment¹¹⁾. The mus-culoskeletal system is necessary to hold a toothbrush and perform oral hygiene procedures¹²⁾. Therefore, the need for oral health care for aging well is emphasized.

Oral problems that frequently affect older adults, such as tooth loss, dry mouth, and chewing limitations, are asso-ciated with poorer quality of life¹³⁾. Poor oral health im-pairs self-esteem and social interaction, which has a negative impact on aging well and mental health¹⁴⁾. Poor oral health has a negative impact on aging well by impai-ring self-esteem and social interaction¹⁵⁾. As such, oral health is essential for cognition, social interaction, and aging well. If oral problems are not resolved, poor health can accelerate¹³⁾. Maintaining teeth enables well-being and social connection. And oral care education reduces the risk of social isolation in older adults¹⁶⁾.

In previous research, studies on the impact of each factor related to oral health have been conducted, comprehensive exploration to determine the direction of oral health research for aging well is insufficient. Therefore, it is necessary to review the research topic through analysis of the main key-words of the study using existing research data.

2.Objectives

Accordingly, this study sought to identify research trends through text analysis of studies related to oral health and aging over the past 12 years. In addition, we aim to iden-tify factors related to oral health in aging well through fre-quent text and text-to-text correlation analysis and provide basic data needed to prevent oral senescence in aging well.

1.Ethics statement

This study utilizes existing data published in PubMed and has low research ethics risk. The collected data is secondary data and does not contain personal information. The study was conducted after Konyang University IRB exemption approval (IRB KYU NON2023-012).

2.Study design

The research data was analyzed based on English literature published in PubMed from 2012 to 2023 aging well and oral health search terms were used. The research period was selected over the past 12 years, starting with the year when aging oral health research increased. There were 201 papers, including reviews and clinical trials, exclu-ding books, documents, and abstracts.

When organizing keywords and MeSH terms in Excel, 115 papers were finally selected, excluding basic experi-mental research related to aging well oral health. The literature was organized by author, title, journal, volume, year of publication, and keywords. Two people cross-exa-mined the keywords and combined similar keywords (Table 1).

Table 1

Research Procedure and Contents

Research procedure	Contents	Details of research
Research data collection	Data collection	∙Aging-well oral health research literature search: Author, title, journal, volume, year of publication, keyword summary
Analyze	Key word analysis	∙ Key word extraction, frequency analysis
	Network analysis	∙ Core node subject cluster analysis, central structure analysis, cohesive structure analysis
Result	Result interpretation	∙ Result interpretation

3.Statistical methods

Network keyword analysis used the Net-Miner 4.0 program. Keyword frequency analysis, degree centrality analysis, and cohesive structure analysis were performed.

Key word frequency analysis was conducted to identify important key words in aging well oral health research. Degree centrality analysis can confirm organic connec-tivity through the degree of connection between keywords. The narrower the spacing between keywords, the higher the correlation¹⁷⁾. Cohesive structure analysis constructs a community of texts with strong cohesion, analyzed clus-tered keywords to identify the close connection between keywords. Cohesive structure analysis is a group of sub-ject words with more intra-group links than inter-group links. The modularity value, an indicator calculated from this analysis, determines group suitability¹⁸⁾. Through co-hesive structure analysis, the interrelationship of key words was identified and clustered concepts were derived. In this study, group 4, Step 70, modularity value was 0.17. If the modularity value is a positive number, it is judged to be modular.

1.Key word frequency analysis of the study subjects

There were 520 keywords presented in 115 academic papers related to aging well oral health. There were a total of 70 key keywords. As for the main keywords 15 key-words with a frequency of 3 or more were identified. Table 2 shows the frequency and ratio of the relevant keywords. The most frequently appearing keyword in aging well oral health research was psychology in 31 articles (26.96%). Next is Adults 19 (16.52%), Sex Factor 17 (14.78%), Adolescent 13 (11.30%), Dental Prosthesis and Alzheimer Disease 11 (9.57%), Dental caries 8 (63.96%), Cognitive. Dysfunction and Bacteria were 7 (6.09%) (Table 2).

Table 2

Key Word Frequency Analysis of the Study Subjects (n=115)

Key word	Number	%	Key word	Number	%
Psychology	31	26.96	Deglutition	4	3.48
Adult	19	16.52	Health policy	3	2.61
Sex factors	17	14.78	Muscle	3	2.61
Adolescent	13	11.30	Frailty	2	1.74
Dental prosthesis	11	9.57	Attitude to health	2	1.74
Alzheimer disease	11	9.57	Caregivers	2	1.74
Dental caries	8	6.96	Quality of life	2	1.74
Cognitive dysfunction	7	6.09	Dementia	1	0.87
Bacteria	7	6.09	Dental care	1	0.87
Diet	5	4.35	Periodontal diseases	1	0.87
Cause of death	5	4.35	Dental plaque	1	0.87
Bite force	4	3.48	Medicare	1	0.87

2.Study subjects’ results of degree centrality analysis

The results of the degree centrality analysis are shown in Table 3. Research keywords with high degree centrality included Sex factors (0.909), Dental caries (0.864), Quality of life (0.833), Tooth loss (0.818), Health status (0.727), and Life expectancy (0.712). This shows that various stu-dies related to aging well oral health are conducted focu-sing on the above keywords.

Table 3

Study Subjects’ Results of Degree Centrality Analysis (n=115)

Key word	Degree centrality	Key word	Degree centrality
Sex factors	0.909	Oral hygiene	0.500
Dental caries	0.864	Preventive	0.500
Quality of life	0.833	Epidemiology	0.470
Tooth loss	0.818	Diagnosis	0.455
Health status	0.727	Diet	0.455
Life expectancy	0.712	Root caries	0.455
Diabetes	0.697	Smoking	0.455
Saliva	0.682	Psychology	0.455
Memory disorders	0.621	Biological	0.455
Social support	0.621	Attitude to health	0.455
Periodontal diseases	0.621	Bite force	0.455
Independent living	0.591	Deglutition	0.455
Health behavior	0.591	Esthetics	0.455
Health services	0.591	Dental care	0.439
Cognitive dysfunction	0.576	Nutrition	0.409
Microbiology	0.576	Adolescent	0.379
Dentition	0.576	Child	0.364
Taste	0.561	Socioeconomic	0.364
Personal satisfaction	0.545	Professional role	0.348
Eating	0.545	Frailty	0.318

The structural analysis of degree centrality is shown in Fig. 1. In the center of the degree centrality map, there are key keywords with high frequency of occurrence: Sex factors (0.909), Dental caries (0.864), Quality of life (0.833), Tooth loss (0.818), Health status (0.727), and Life expec-tancy (0.712). Over the past 12 years, research on aging well oral health has focused on various keywords such as Sex factors, Dental caries, Quality of life, Tooth loss, Health status, Life expectancy, Diabetes, Saliva, Memory disor-ders, Social support, and Periodontal diseases. It was con-firmed that it was performed properly.

Fig. 1. Structural analysis of degree centrality.

The results of grouping keywords with high cohesion based on the modularity value presented in the community analysis are shown in Fig. 2. Modularity value ranges from −1 to 1, and if it appears as a positive number, it means that modularity is appropriate.

Fig. 2. Group 1 network map keyword.

The modularity value of this study was 0.175 and there were 4 community groups. Aging Well Oral Health Research Results: Group 1 was mastication and nutrition, Group 2 was research on oral diseases, systemic diseases and manage-ment, Group 3 was research on oral health, mental health and costs by life cycle, and Group 4 was oral frailty and quality of life. It consisted of research.

Group 1, there were 14 keywords, and the average degree centrality index was 0.367. Key keywords consisted of Saliva (0.682), Taste (0.561), Eating (0.545), Nutrition (0.409), Edentulous (0.258), Prevalence, Mastication (0.227), and personal satisfaction (0.545). This was grouped into research on chewing and nutrition related to aging well oral health (Table 4, Fig 3).

Table 4

Group 1 (Mastication and Nutrition) Network Map Keyword

Key word	Degree centrality
Eating	0.545
Saliva	0.682
Taste	0.561
Nutrition	0.409
Edentulous	0.258
Denture	0.152
Mastication	0.227
Jaw	0.182
Stress	0.167
Personal satisfaction	0.545
Prevalence	0.258
Nursing home	0.152
Comorbidity	0.091
Sex factors	0.909

Fig. 3. Cohesive structure analysis of university-linked education.

Group 2, there were 12 keywords, and the average degree centrality was 0.400. Key keywords include Dental caries (0.864), Periodontal Diseases (0.621), Microbio-logy (0.576), Bacteria (0.152), Inflammation (0.197), Oral Hygiene (0.500), Diabetes (0.697), Dementia (0.182), Pneu-monia (0.152), Cognitive Dysfunction (0.576), Disease Pro-gression (0.197), and Medicare (0.091). It was confirmed that this consists of research on oral diseases and serious diseases and management related to aging well oral health (Table 5, Fig. 4).

Table 5

Group 2 (Oral diseases, Systemic Diseases and Manage-ment) Network Map Keyword

Key word	Degree centrality
Dental caries	0.864
Periodontal diseases	0.621
Microbiology	0.576
Bacteria	0.152
Inflammation	0.197
Oral hygiene	0.500
Diabetes	0.697
Dementia	0.182
Cognitive dysfunction	0.576
Pneumonia	0.152
Disease progression	0.197
Medicare	0.091

Fig. 4. Group 2 network map keyword.

Group 3 had 17 keywords, and the average degree centrality was 0.429. Key keywords are Life Expectancy (0.712), Child (0.364), Adolescent (0.379), Adult (0.182), Socioeconomic (0.364), Epidemiology (0.470), Tooth loss (0.818), Dental care (0.439), Fluoridation (0.182), Profe-ssional role (0.348). It was composed of Depression (0.273), Memory disorders (0.621), Dentition (0.576), Health promotion (0.288), Health status (0.727), Cost (0.273), and Insurance (0.273). It was confirmed that this consists of studies related to oral health, mental health, and costs by life cycle (Table 6, Fig. 5).

Table 6

Group 3 Network (Oral Health, Mental Health) Map Keyword

Key word	Degree centrality
Life expectancy	0.712
Child	0.364
Adolescent	0.379
Adult	0.182
Socioeconomic	0.364
Epidemiology	0.470
Tooth loss	0.818
Dental care	0.439
Fluoridation	0.182
Professional role	0.348
Depression	0.273
Memory disorders	0.621
Dentition	0.576
Health promotion	0.288
Health status	0.727
Cost	0.273
Insurance	0.273

Fig. 5. Group 3 network map keyword.

Group 4 had 23 keywords, and the average degree centrality was 0.434. Key keywords are Quality of life (0.833), Frailty (0.318), Root caries (0.455), Burning syn-drome (0.242), Xerostomia (0.106), Deglutition (0.455), Muscle (0.273), Bite force (0.455), Diet (0.455), Malnu-trition (0.288), Esthetics (0.455), and Diagnosis (0.455). And psychology (0.455), Biological (0.455), Preventive (0.500), Smoking (0.455), Social support (0.621), Health behavior (0.591), Health services (0.591), Attitude to health (0.455), Independent living (0.591), Hospitalization (0.242), and Physical functional performance (0.242). It was confirmed that this consists of oral frailty symptoms and quality of life (Table 7, Fig. 6).

Table 7

Group 4 (Oral Frailty and Quality of Life) Network Map Keyword

Key word	Degree centrality	Key word	Degree centrality
Quality of life	0.833	Psychology	0.455
Frailty	0.318	Biological	0.455
Root caries	0.455	Preventive	0.500
Burning syndrome	0.242	Smoking	0.455
		Social support	0.621
Xerostomia	0.106	Health behavior	0.591
Deglutition	0.455	Health services	0.591
Muscle	0.273	Attitude to health	0.455
Bite force	0.455	Independent living	0.591
Diet	0.455	Hospitalization	0.242
Malnutrition	0.288	Physical functional performance	0.242
Esthetics	0.455
Diagnosis	0.455

Fig. 6. Group 4 network map key-word.

1.Interpretation and comparison to previous studies

As a result of analyzing keywords in research related to oral health, which is an essential factor for aging well, the keywords with the highest frequency were general characteri-stics of research subjects, oral factors, and mental factors.

Oral factors included Bacteria, Dental caries, and Dental Prosthesis, and mental factors included Psychology, Cog-nitive dysfunction, and Alzheimer Disease. It has been confirmed that many studies on cognitive influencing factors related to oral health have been conducted for aging well over the past 12 years.

As a result of the centrality analysis, the core topics of aging well oral health were Dental caries, Tooth loss, Health status, Quality of life, and Life expectancy. Tooth loss and impaired oral health lead to physical decline and dysfun-ction, as they contribute to aging¹⁹⁾. This confirmed that keywords related to oral disease, health, and quality of life were the focus of the study, taking into account life expectancy in a super-aging society.

As a result of the cohesive structure analysis, group 1 was conceptualized as mastication and nutrition. Although masticatory parameters change with age, aging itself does not impair masticatory function. Loss of teeth and lack of saliva in old age are causes of mastication disorders. Food bolus formation for swallowing depends on the number of mastications, muscle strength, and the amount of saliva released. This shows the negative consequences of eating habits and nutrition, confirming the importance of chewing and nutrition for aging well²⁰⁾.

Group 2 confirmed studies on the effects of oral diseases and systemic diseases such as inflammation, diabetes, dementia, pneumonia, and cognitive dysfunction. These were studies that recognized the importance of oral health contributions such as type 2 diabetes, periodontitis, pneumonia in elderly people with dysphagia, and patho-physiological effects. In order to age healthily, it is impor-tant to be aware of the impact of poor oral health²¹⁾.

Group 3 consisted of oral health, mental health, and costs by life cycle. Preventing tooth loss is essential for oral care throughout each life cycle²²⁾. In order to maintain oral health throughout each life cycle, the need for self-management education and the preventive effects of professional care was suggested. In particular, educational programs inclu-ding oral exercises are effective in improving articulation, functional performance of the tongue, and swallowing func-tion in older adults without disabilities²³⁾.

Such oral function has an important impact on depre-ssion and cognitive health in old age. Depression affects oral health due to neglect of oral hygiene, intake of cario-genic nutrition, and avoidance of necessary dental care. This increases the risk of dental caries and periodontal disease. The severity of depression in older adults increases with the number of missing tooth, number of cavities, and prevalence of dry mouth²⁴⁾. And Mastication disorders and cognitive disorders are interrelated²⁵⁾, Therefore Policy support is needed to improve oral health and health in the age of super-aging.

Some studies have shown that disparities in an indi-vidual’s oral health are primarily influenced by socioe-conomic conditions and the availability and accessibility of oral health services²⁶⁾. Therefore, policy support research for oral health promotion is needed to improve this.

Group 4 was conceptualized in terms of oral senescence symptoms and quality of life.

Oral frailty is associated with sarcopenia due to frequent habitual intake of inappropriate food and poor nutritional status. And low tongue pressure reflects frailty and dys-phagia in older people ²⁷⁾. As a result, oral frailty is asso-ciated with mastication and swallowing problems and causes nutritional deficiencies. Some studies suggest that sarco-penia is associated with mortality²⁸⁾.

Masticatory disorders in older adults can lead to decreased nutrition, communication, self-esteem, and quality of life¹⁵⁾. Many studies are evaluating the impact of various aspects such as self-esteem, social interaction, and school or work performance to evaluate the impact of oral health on quality of life ¹⁵⁾.

In summary, Factors affecting oral health with increa-sing age were investigated including root caries, bite force, burning syndrome, and xerostomia. Research trends on well-aging include chewing and nutrition, oral and sys-temic diseases, oral health and mental health, oral aging, and quality of life. In order to live a healthy old age in a super-aging society, it was necessary to recognize and manage the importance of oral health.

2.Suggestion

In the results of this study, the aging well oral health study consisted of chewing and nutrition, oral disease and mental disease, oral health and mental health, oral frailty, and quality of life. As the elderly population has increased worldwide, the development of a systematic intervention program was necessary to improve oral health throughout the life cycle. And oral senescence emphasizes the risk of developing dementia. There is a need for continued research on the impact of oral dysfunction on mental health and quality of life in the super-aging society. Lastly, in order to age well in a super-aging society, exploratory research from various perspectives is needed to improve quality of life by preventing oral senescence.

3.Limitations

In this study, network keyword analysis was conducted on 12 years of literature related to aging and oral health. In future research, it is necessary to expand the period and target research period and conduct big data analysis to increase generalizability.

None.

No potential conflict of interest relevant to this article was reported.

This study was approved by the institutional review board of Konyang University (IRB No. NON2023-012).

None.

Dataset1. 115 articles searched in PubMed.