Table 1.
Characteristics of included studies.
| Study | Regions; Name of cohort | Study design | Age(years) | Follow-up times (years) | Sample size | Cognitive assessment | Tooth loss assessment | Results |
|---|---|---|---|---|---|---|---|---|
| Shimazaki et al., 2001 | Japan; Kitakyushu City | Prospective cohort | 59–107 | 6 | 156/517 | Medical records; Incident and mortality dementia | Number of remaining teeth (reference ≥20 teeth) | With denture, OR (95%CI) 1–19 teeth: OR 1.9 (0.8–4.6) Edentulous:1.7 (0.7–4.0) Without denture, OR (95%CI) 1–19 teeth: 2.3 (0.9–5.8) Edentulous: 2.4 (0.9–6.5) |
| Stein et al., 2007 | USA; the Nun Study | Retrospective cohort | 40–75 | 12 | 32/144 | the Mini-Mental State Examination and Activities of Daily Living; Incident dementia | Number of remaining teeth excluding non-third molars (reference 10–28 teeth) | HR (95%CI): 17–28: Reference 10–16:HR 0.4 (0.10–1.76) 1–9:HR 1.8 (0.58–5.46) 0: HR 0.9 (0.25–3.12) 10–28: Reference 0–9 teeth: HR 2.20(1.1–4.5) |
| Arrive et al., 2012 | France; The Personnes Age'es QUID (PAQUID) Study | Prospective cohort | 66–80 | 15 | 72/405 | DSM-III Revised; Incident dementia | Number of missing teeth (reference < 11 teeth) | Higher school level, HR (95%CI): ≥11 teeth: 1.07(0.57–2.02) Unified: 0.93(0.5–1.75) # Lower school level: ≥11 teeth: 0.30(0.11–0.79) Unified: 3.33(1.27–8.73) # |
| Paganini-Hill et al., 2012 | USA; The Leisure World Cohort Study | Retrospective cohort | 52–105 (median 81) | 18 | 1145/5468 | Follow-up questionnaires, hospital records, death certificates, and in-person evaluations; Incident dementia | Number of remaining teeth (reference ≥26 teeth) | Men, HR (95%CI): 16–25 teeth: 1.17 (0.86–1.58) 1–15 teeth: 1.21 (0.84–1.73) 0 teeth: 1.20 (0.77–1.87) Women, HR (95%CI) 16–25 teeth: 0.94 (0.80–1.10) 1–15 teeth: 0.96 (0.79–1.17) 0 teeth: 1.07 (0.84–1.36) |
| Yamamoto et al., 2012 | Japan; the Aichi Gerontological Evaluation Study (AGES) Project | Prospective cohort | ≥ 65 | 4 | 220/4425 | Standardized questionnaire; Incident dementia | Number of remaining teeth (reference ≥20 teeth) | HR (95%CI) with/without dentures: ≤ 19 teeth: 1.01(0.67–1.51) Few teeth with dentures: 2.70 (1.84–3.94) Few teeth without dentures 4.57 (2.63–7.94) |
| Batty et al., 2013 | UK; Action in Diabetes and Vascular disease: Preterax and Diamicron Modified-Release Controlled Evaluation (ADVANCE) trial | Prospective cohort | 55–88 | 5 | 109/1140 | DSM-IV | Number of remaining teeth (reference ≥22 teeth) | HR (95%CI): 1–21 teeth: 1.24 (1.05, 1.46) 0 teeth: 1.48 (1.24, 1.78) |
| Stewart et al., 2015 | Sweden; the Prospective Population Study of Women (PPSW) in Gothenburg | Retrospective cohort | 25–74 | 37 | 158/697 | DSM-III Revised; Incident dementia | Number of remaining Teeth(reference ≥25 teeth) | Women, OR (95%CI) ≥25 teeth: 21–24 teeth:1.24 (0.74–2.09) 9–20 teeth: 1.25 (0.72–2.17) <9 teeth: 1.81 (1.03–3.19) Lowest vs. Highest Quartile: 1.62 (0.84–3.11) |
| Takeuchi et al., 2017 | Japan; The Hisayama Study | Prospective cohort | ≥60 | 5 | 180/1566 | DSM-III Revised; Incident dementia | Number of remaining Teeth(reference ≥20 teeth) | HR (95% CI) 10–19 teeth:1.62 (1.06–2.46) 1–9teeth: HR 1.81 (1.11–2.94) 0 teeth: HR 1.63 (0.95–2.80) |
DSM-IV, Diagnostic and Statistical Manual of Mental Disorders-IV; HR, hazard ratio; OR, odds ratio; CI, confidential interval; CCD, Cardiovascular and cerebrovascular diseases.
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Unified data were from the reciprocal of the original data.