Table 3.
Characteristics of Studies Integrated relating to RQ1–1.
| No | Authors | Study Design | Study Population | Intervention | Comparison | Outcome |
|---|---|---|---|---|---|---|
| 1 * | Matsubara et al., 2021 | RCT | 50 older adults aged 65 and above (MMSE score ≥21 to ≤26) | N = 25 intervention group (mean age: 77.0 years) | N = 25 control group (mean age: 72.8 years) | MMSE, chewing ability with gum chewing, and masticatory performance with test gummy jelly |
| 2 * | Tan et al., 2020 | Pilot quasi-experimental study | 4 completely edentulous patients (mean age: 73.0 ± 1.4years; 2 males, 2 females) | N= 4 implant retained removable denture | N = 4 complete removable denture | 3MS - Modified MMSE, Masticatory performance using color changing gum |
| 3 | Cho et al., 2021 | Case-control | 308 Koreans aged ≥ 65 (mean age: 78.69 6 ± 5.76 years, 68 males, 240 females | N = 89, poor masticatory function; N=109, with cognitive impairment (MMSE score <24) | N = 99, good masticatory function; N= 199, normal (MMSE score ≥ 24) | MMSE, Chewing ability for 5 food items, subjective masticatory ability |
| 4 | Jung et al., 2022 | Case-control | 295 Korean adults aged > 60 years (85 males, 200 females) | N = 100, poor masticatory function | N = 109, good masticatory function | MMSE |
| 5 | Kim et al., 2017 | Case-control | 295 Koreans aged ≥ 70 | N = 60, poor masticatory function; N= 59, with cognitive impairment (MMSE score ≤ 20) | N = 56, good masticatory function; N= 236, normal (MMSE score ≥ 21) | MMSE, Masticatory Performance using color changing gum |
| 6 | Kimura et al., 2013 | Case-control | 269 Japanese aged ≥ 75 (mean age 80.6 ± 4.7 years; 88 males, 181 females) | N = 105, poor masticatory function | N = 164, good masticatory function | MMSE, HDSR, FAB |
| 7 | Shin et al., 2020 | Case-control | 101 Korean women aged ≥ 65 (mean age: 80.64 ± 4.83 years) | N = 29, poor masticatory function; N= 40, with cognitive impairment (MMSE score <24) | N = 36, good masticatory function; N= 61, normal (MMSE score ≥ 24) | MMSE, Masticatory Performance using color-changing gum |
| 8* | Weijenberg et al., 2015 | Case-control | 114 Dutch older persons with dementia aged ≥ 67 | N = 56, poor masticatory function (mean age: 85.2 ± 6.4 years; 4 males, 52 females) | N = 58, good masticatory function (mean age: 85.3 ± 5.4 years; 11 males, 47 females) | MMSE, attention, working memory |
| 9 | Kim et al., 2020 | Case-control | 7029 Korean adults > 45 years | N = 1243, poor masticatory function; N= 2043, with cognitive impairment (MMSE score <24, mean ag:e 75.39 ± 0.21 years; 624 males, 1419 females) | N = 2868, good masticatory function; N= 4986, normal (MMSE score ≥ 24, mean age: 65.38 ± 0.12 years; 2363 males, 2623 females) | MMSE, Chewing ability using self-report questionnaire |
| 10 | Seraj et al., 2017 | Case-control | 50 older adults aged ≥ 60 (25 males, 25 females) | N = 26, poor masticatory function; N= 31, with cognitive impairment (MMSE score <24, mean age: 73.5 ± 11.8 years; 14 males, 17 females) | N = 24,good masticatory function; N= 19, normal (MMSE score ≥ 24, mean age: 67.7 ± 5.4 years; 11 males, 8 females) | MMSE, Index of Chewing ability (questionnaire) |
| 11 | Takehara et al., 2020 | Case-control | 369 Australian men aged ≥ 78 (mean age: 83.8 ± 4.2 years) | N = 101, poor masticatory function; N= 17, with cognitive impairment (MMSE score <24) | N = 268, good masticatory function; N= 352, normal (MMSE score ≥ 24) | MMSE, Chewing ability for 11 food items |
| 12 * | Elsig et al., 2015 | Case-control | 51 older adults aged ≥ 75 | N = 29, with Dementia (mean age: 82.5 ± 6.3 years; 7 males, 22 females) | N = 22, normal (19) or with mild cognitive impairment (3) (mean age: 81.9 ± 6.5 years; 5 males, 17 females) | Masticatory Performance using two-color mixing test |
| 13 * | Miura et al., 2003 | Case-control | 88 Japanese women aged ≥ 65 | N = 44, with cognitive impairment (HDSR score ≤ 20, mean age: 81.1 ± 5.5 years) | N = 44, normal (HDSR score ≥ 21, mean age: 82.3 ± 8.0 years) | HDSR, Chewing ability using food intake questionnaire |
| 14 * | Campos et al., 2017 | Case-control | 32 older adults with removable dentures (11 completely edentulous, 5 partially edentulous in each group) | N = 16, with mild Alzheimer’s Disease (mean age: 76.7 ± 6.3 years; 8 males, 8 females) | N = 16, healthy (mean age: 75.23 ± 4.4 years; 8 males, 8 females) | Masticatory Performance using Optocal artificial test food |
| 15 * | Kugimiya et al., 2019 | Cross-sectional | 1118 Japanese aged ≥ 70 (MMSE ≥24; mean age: 77.0 ± 4.7 years; 445 males, 673 females) | Comparison among gender | Comparison among gender | MMSE |
*Studies not included in the meta-analyses but considered as evidence (see Discussion).
RQ: Research question; RCT: Randomized Controlled Trial; MMSE: Mini-Mental State Examination; HDSR: Hasegawa Dementia Scale-Revised; FAB: Frontal Assessment Battery.