Impact of number of functional teeth on independence of Japanese older adults

Kenji Maekawa^{1

2}, Tomoko Ikeuchi³, Shoji Shinkai^{3

4}, Hirohiko Hirano³, Masahiro Ryu^{1

5}, Katsushi Tamaki^{1

6}, Hirofumi Yatani^{1

7}, Takuo Kuboki^{1

2}; Kusatsu ISLE Study Working Group Collaborators; Aya Kimura-Ono^{1

8}, Takeshi Kikutani^{1

9}, Takashi Suganuma^{1

10}, Yasunori Ayukawa^{1

11}, Tomoya Gonda^{1

7}, Toru Ogawa^{1

12}, Masanori Fujisawa^{1

13}, Shoichi Ishigaki^{1

7}, Yutaka Watanabe^{3

14}, Akihiko Kitamura³, Yu Taniguchi¹⁵, Yoshinori Fujiwara³, Ayako Edahiro³, Yuki Ohara³, Junichi Furuya¹⁰, Junko Nakajima⁵, Kento Umeki¹⁶, Kentaro Igarashi¹⁶, Yasuhiro Horibe⁵, Yoshihiro Kugimiya⁵, Yasuhiko Kawai¹⁶, Hideo Matsumura¹⁷, Tetsuo Ichikawa¹⁸, Shuji Ohkawa¹³, Kazuyoshi Baba¹⁰

Affiliations

¹ Research Planning and Promotion Committee, Japan Prosthodontic Society, Tokyo, Japan.
² Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.
³ Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
⁴ Kagawa Nutrition University, Sakado, Japan.
⁵ Tokyo Dental College, Tokyo, Japan.
⁶ Kanagawa Dental University Graduate School, Yokosuka, Japan.
⁷ Osaka University Graduate School of Dentistry, Osaka, Japan.
⁸ Okayama University Hospital, Okayama, Japan.
⁹ The Nippon Dental University, Tokyo, Japan.
¹⁰ Showa University School of Dentistry, Tokyo, Japan.
¹¹ Kyushu University Faculty of Dental Science, Fukuoka, Japan.
¹² Tohoku University Graduate School of Dentistry, Sendai, Japan.
¹³ Meikai University School of Dentistry, Sakado, Japan.
¹⁴ Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan.
¹⁵ National Institute for Environmental Studies, Ibaraki, Japan.
¹⁶ Nihon University School of Dentistry at Matsudo, Chiba, Japan.
¹⁷ Nihon University School of Dentistry, Tokyo, Japan.
¹⁸ Tokushima University Graduate School, Institute of Biomedical Sciences, Tokushima, Japan.

PMID: 36408675
PMCID: PMC10099778
DOI: 10.1111/ggi.14508

Impact of number of functional teeth on independence of Japanese older adults

Kenji Maekawa et al. Geriatr Gerontol Int. 2022 Dec.

. 2022 Dec;22(12):1032-1039.

doi: 10.1111/ggi.14508. Epub 2022 Nov 21.

Authors

Affiliations

¹ Research Planning and Promotion Committee, Japan Prosthodontic Society, Tokyo, Japan.
² Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.
³ Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
⁴ Kagawa Nutrition University, Sakado, Japan.
⁵ Tokyo Dental College, Tokyo, Japan.
⁶ Kanagawa Dental University Graduate School, Yokosuka, Japan.
⁷ Osaka University Graduate School of Dentistry, Osaka, Japan.
⁸ Okayama University Hospital, Okayama, Japan.
⁹ The Nippon Dental University, Tokyo, Japan.
¹⁰ Showa University School of Dentistry, Tokyo, Japan.
¹¹ Kyushu University Faculty of Dental Science, Fukuoka, Japan.
¹² Tohoku University Graduate School of Dentistry, Sendai, Japan.
¹³ Meikai University School of Dentistry, Sakado, Japan.
¹⁴ Faculty of Dental Medicine, Hokkaido University, Sapporo, Japan.
¹⁵ National Institute for Environmental Studies, Ibaraki, Japan.
¹⁶ Nihon University School of Dentistry at Matsudo, Chiba, Japan.
¹⁷ Nihon University School of Dentistry, Tokyo, Japan.
¹⁸ Tokushima University Graduate School, Institute of Biomedical Sciences, Tokushima, Japan.

PMID: 36408675
PMCID: PMC10099778
DOI: 10.1111/ggi.14508

Abstract

Aim: To examine the relationship between the number of present and functional teeth at baseline and future incidence of loss of independence.

Methods: Participants were community-dwelling older individuals who participated in a comprehensive geriatric health examination conducted in Kusatsu town, Japan, between 2009 and 2015. The primary endpoint was the incidence of loss of independence among participants, defined as the first certification of long-term care insurance in Japan. The numbers of present and functional teeth at baseline were determined via an oral examination. Demographics, clinical variables (e.g., history of chronic diseases and psychosocial factors), blood nutritional markers, physical functions, and perceived masticatory function were assessed.

Results: This study included 1121 individuals, and 205 individuals suffered from loss of independence during the follow-up period. Kaplan-Meier estimates of loss of independence for participants with smaller numbers of present and functional teeth were significantly greater than for those with larger numbers of teeth. Cox proportional hazard analyses indicated that a smaller number of present teeth was not a significant risk factor after adjusting for demographic characteristics. However, the number of functional teeth was a significant risk factor after the adjustment (hazard ratio: 1.975 [1.168-3.340]). Additionally, higher hazard ratios were observed in other adjusted models, but they were not statistically significant.

Conclusions: The number of functional teeth may be more closely related to the future incidence of loss of independence than the number of present teeth. This novel finding suggests that prosthodontic rehabilitation for tooth loss possibly prevents the future incidence of this life-event. Geriatr Gerontol Int 2022; 22: 1032-1039.

Keywords: community-dwelling older adults; functional teeth; loss of independence; oral health; present teeth.

PubMed Disclaimer

Figures

**Figure 1**
Flow diagram for the selection of study participants.

**Figure 2**
Kaplan–Meier estimates of the loss of independence categorized by numbers of present teeth (left) and functional teeth (right). Significant statistical differences were observed using log‐rank tests (number of present teeth: P < 0.001; number of functional teeth: P = 0.022).

See this image and copyright information in PMC

Cited by

Differences in Cumulative Long-Term Care Costs by Dental Visit Pattern Among Japanese Older Adults: The JAGES Cohort Study.
Kiuchi S, Takeuchi K, Saito M, Kusama T, Nakazawa N, Fujita K, Kondo K, Aida J, Osaka K. Kiuchi S, et al. J Gerontol A Biol Sci Med Sci. 2024 Sep 1;79(9):glae194. doi: 10.1093/gerona/glae194. J Gerontol A Biol Sci Med Sci. 2024. PMID: 39101529 Free PMC article.
The symptom network of oral health conditions in older populations with oral frailty: a cross-sectional study.
Chengrui Z, Ying X, Wei L, Bin C. Chengrui Z, et al. BMC Oral Health. 2025 Apr 1;25(1):471. doi: 10.1186/s12903-025-05795-9. BMC Oral Health. 2025. PMID: 40170022 Free PMC article.
Association between number of functional teeth and physical function among community-dwelling older adults: Korean Frailty and Aging Cohort Study.
Lim N, Lee D, Shin SY, Won CW, Kim M. Lim N, et al. BMC Geriatr. 2024 Dec 20;24(1):1024. doi: 10.1186/s12877-024-05585-y. BMC Geriatr. 2024. PMID: 39707218 Free PMC article.

References

1. Watanabe Y, Hirano H, Arai H et al. Relationship between frailty and oral function in community‐dwelling elderly adults. J Am Geriatr Soc 2017; 65: 66–76. - PubMed
1. Kamdem B, Seematter‐Bagnoud L, Botrugno F, Santos‐Eggimann B. Relationship between oral health and Fried's frailty criteria in community‐dwelling older persons. BMC Geriatr 2017; 17: 174. - PMC - PubMed
1. Horibe Y, Watanabe Y, Hirano H et al. Relationship between masticatory function and frailty in community‐dwelling Japanese elderly. Aging Clin Exp Res 2018; 30: 1093–1099. - PubMed
1. Komiyama T, Ohi T, Miyoshi Y et al. Association between tooth loss, receipt of dental care, and functional disability in an elderly Japanese population: the Tsurugaya project. J Am Geriatr Soc 2016; 64: 2495–2502. - PubMed
1. Komiyama T, Ohi T, Miyoshi Y et al. Relationship between status of dentition and incident functional disability in an elderly Japanese population: prospective cohort study of the Tsurugaya project. J Prosthodont Res 2018; 62: 443–448. - PubMed

MeSH terms

Actions
Actions
Actions
Actions
Actions
Actions
Actions

LinkOut - more resources

Full Text Sources

Save citation to file

Email citation

Add to Collections

Add to My Bibliography

Your saved search

Create a file for external citation management software

Your RSS Feed

Impact of number of functional teeth on independence of Japanese older adults

Affiliations

Impact of number of functional teeth on independence of Japanese older adults

Authors

Affiliations

Abstract

Figures

Similar articles

Cited by

References

MeSH terms

LinkOut - more resources

Full Text Sources