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Table 1 Baseline characteristics of patients and their dental clinics according to tooth loss

From: A multilevel analysis of the importance of oral health instructions for preventing tooth loss: The 8020 Promotion Foundation Study of Japanese Dental Patients

  Tooth loss p value
Absence (n = 1797) Presence (n = 691)
Patient-level variables Mean (SD)  
 Age (years) 57.0 (14.7) 65.5 (11.2)  < 0.001
 Number of teeth 24.9 (4.5) 21.2 (6.0)  < 0.001
 Number of decayed teeth 0.4 (1.2) 0.6 (1.4) 0.009
 Mean PPD (mm) 2.8 (0.8) 3.2 (1.0)  < 0.001
 BOP (%) 23.3 (25.5) 30.4 (28.5)  < 0.001
n (%)
 Gender
  Male 549 (67.3) 267 (32.7)  < 0.001
  Female 1248 (74.6) 424 (25.4)  
 Smoking
  Never 1307 (75.2) 430 (24.8)  < 0.001
  Past 362 (65.5) 191 (34.5)  
  Current 128 (64.6) 70 (35.4)  
 Diabetes mellitus
  No 1702 (72.9) 632 (27.1) 0.002
  Yes 95 (61.7) 59 (38.3)  
 Tooth brushing frequency (times per day)
  ≥ 3 685 (76.8) 207 (23.2)  < 0.001
  2 917 (70.8) 379 (29.2)  
  ≤ 1 195 (65.0) 105 (35.0)  
 Use of secondary oral hygiene productsa
   Yes 1356 (73.0) 502 (27.0) 0.082
  No 441 (70.0) 189 (30.0)  
 Bleeding during tooth brushing
  No 1,192 (75.6) 385 (24.4)  < 0.001
  Yes 605 (66.4) 306 (33.6)  
 Eating between meals
  No 205(63.5) 118 (36.5)  < 0.001
  Sometimes 986 (72.5) 374 (27.5)  
  Everyday 606 (75.3) 199 (24.7)  
 Reason for dental visit
  Treatment 527 (63.0) 309 (37.0)  < 0.001
  Both treatment and maintenance 313 (68.6) 143 (31.4)  
  Maintenance 957 (80.0) 239 (20.0)  
 Education level (years)
  ≥ 13 933 (77.2) 276 (22.8)  < 0.001
  ≤ 12 868 (67.6) 415 (32.4)  
 Economic status
  Low 307 (72.1) 119 (27.9) 0.728
  Middle 1,241 (72.6) 468 (27.4)  
  High 249 (70.5) 104 (29.5)  
 Working status
  Yes 1,079 (77.9) 306 (22.1)  < 0.001
  No 718 (65.1) 385 (34.9)  
Clinic-level variablesb
 Age of dental clinic director
  30s or 40s 600 (76.5) 184 (23.5) 0.005
  50s 907 (70.5) 380 (29.5)  
  60s or over 290 (69.5) 127 (30.5)  
 Gender of dental clinic director
  Male 1,680 (72.0) 653 (28.0) 0.201
  Female 117 (75.5) 38 (24.5)  
 Number of dental hygienists
  0 295 (69.6) 129 (30.4) 0.005
  1–3 1,199 (71.4) 478 (28.6)  
  ≥ 4 311 (78.7) 84 (21.3)  
 Time for oral health instruction (min)
  0 243 (68.5) 112 (31.5) 0.003
  1–9 570 (69.0) 256 (31.0)  
  10–19 613 (74.3) 212 (25.7)  
  ≥ 20 371 (77.0) 111 (23.0)  
  1. SD standard deviation, PPD probing pocket depth, BOP breeding on probing
  2. aDental floss or interdental brush
  3. bThese are the clinic information for each patient based on linking clinic data to patient data