Table 1.
Characteristics of the Study Population
| n (%) | |||
|---|---|---|---|
| Variable | Cases (N=131) | Controls (N=1019) | p-Valuea |
| Age, years, mean±SD | 32.9±4.1 | 32.3±4.2 | 0.94 |
| Region of residence | <0.0001 | ||
| Fukuoka prefecture | 52 (39.7) | 679 (66.6) | |
| Other than Fukuoka Prefecture in Kyushu | 76 (58.0) | 238 (23.4) | |
| Okinawa prefecture | 3 (2.3) | 102 (10.0) | |
| Education, years | 0.47 | ||
| <13 | 23 (17.6) | 211 (20.7) | |
| 13–14 | 50 (38.2) | 338 (33.2) | |
| ≥15 | 58 (44.3) | 470 (46.1) | |
| Smoking | 0.21 | ||
| Never | 86 (65.7) | 723 (71.0) | |
| Ever | 45 (34.4) | 296 (29.1) | |
| Toothbrushing frequency, times/day | 0.32 | ||
| <2 | 17 (13.0) | 131 (12.9) | |
| 2 | 58 (44.3) | 518 (50.8) | |
| ≥3 | 56 (42.8) | 370 (36.3) | |
| Use of an interdental brush | 0.30 | ||
| No | 64 (48.9) | 547 (53.7) | |
| Yes | 67 (51.2) | 472 (46.3) | |
a
χ2 test or t-test.