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Table 2 Agreement and reliability of repeated measurements for four methods in terms of the distance from 0M1 related to a single tooth

From: New insights in the reproducibility of visual and electronic tooth color assessment for dental practice

  Visual 2D Visual 3D Electronical 2D Electronical 3D
Value Value Value Value
Number of paired observations 840a 840a 839b 840b
Mean distance (SD) d1 from 0M1 for the 1st measurement 15.0 (3.28) 13.4 (2.89) 15.8 (2.97) 13.1 (3.69)
Mean distance (SD) d2 from 0M1 for the 2nd measurement 14.9 (3.23) 13.3 (2.76) 15.9 (2.94) 13.4 (3.73)
Pooled SD of the 1st and 2nd measurement 3.25 2.83 2.96 3.71
Difference d2 – d1 (standard deviation) −0.17 (1.98) −0.08 (2.11) 0.09 (1.42) 0.26 (2.09)
Agreement within |d(0M1)|  < 2.7, proportion (95% CI) 83.7 (81.0–86.1)*** 70.6 (67.4–73.7)** 93.6 (91.7–95.1)***,† 77.3 (74.3–80.1)**,***
Agreement within |d(0M1)|  < 3.7, proportion (95% CI) 94.0 (92.2–95.6) 94.0 (92.2–95.6) 97.0 (95.6–98.1) 93.1 (91.2–94.7)***,†
Limits of agreement −4.04 – 3.70 − 4.21 – 4.06 −2.70 – 2.88 −3.84 – 4.36
Number of observations outside the limits of agreement total (lower; higher); expected: 30–55 50 (38; 12) 38 (13; 25) 53 (26; 27) 52 (20; 32)
Largest mean d(0M1) value 22.2 20.7 24.8 24.9
Smallest mean d(0M1) value 11.2 7.3 11.2 3.3
SEM(2,1) 1.400 1.489 1.007 1.489
SEM(3,1) 1.396 1.489 1.005 1.479
SDCD(2,1) 3.88 4.13 2.79 4.13
SDCD(3,1) 3.87 4.13 2.79 4.10
ICC(1,1) (95% CI) 0.81 (0.79–0.84)**,*** 0.72 (0.69–0.75)** 0.88 (0.87–0.90)*** 0.84 (0.82–0.86)***
ICC(2,1) (95% CI) 0.81 (0.79–0.84)**,*** 0.72 (0.69–0.75)** 0.88 (0.87–0.90)*** 0.84 (0.82–0.86)***
ICC(3,1) (95% CI) 0.82 (0.79–0.84)**,*** 0.72 (0.69–0.75)** 0.88 (0.87–0.90)*** 0.84 (0.82–0.86)***
  1. SD denotes standard deviation, CI denotes confidence interval, SEM denotes standard error of measurement, SDCD denotes smallest detectable color difference, ICC denotes intraclass correlation coefficient
  2. a V1 versus V2, V3 versus V4, V5 versus V6 acc. to the flow chart
  3. b E1 versus E2, E3 versus E4, E5 versus E6 acc. to the flow chart
  4. Classifications for the interpretation of agreement
  5. ** good [60–80); *** very good [80–92); excellent [92–100]
  6. Classifications for the interpretation of reliability in terms of ICC
  7. * fair [0.4–0.6); ** good [0.6–0.8); *** very good [0.8–0.92); excellent [0.92–1.0]