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. 2026 Apr 17;26:921. doi: 10.1186/s12903-026-08319-1

Table 2.

L*, a*, and b* values of clear aligners at baseline (t0), after staining (t1), and after cleaning (t2) for each experimental group

Timepoint L* (Mean ± SD) a* (Mean ± SD) b* (Mean ± SD)

Group 1

ICC + 0 min

Baseline (t0) 86.31 ± 8.09A 1.01 ± 0.55A 3.98 ± 1.86A
After Staining (t1) 83.64 ± 2.79AB -1.41 ± 1.53B 16.97 ± 4.41B
After cleaning (t2) 85.77 ± 3.87B -0.45 ± 1.03B 13.48 ± 2.56C

Group 2

ICC + 5 min

Baseline (t0) 81.23 ± 7.09A 1.22 ± 0.54A 3.37 ± 1.19A
After Staining (t1) 83.83 ± 4.86AB -0.81 ± 1.07B 16.56 ± 4.04B
After cleaning (t2) 81.59 ± 5.95B -1.31 ± 0.77B 14.90 ± 3.02C

Group 3

ICC + 10 min

Baseline (t0) 78.26 ± 5.58A 1.09 ± 0.76A 3.87 ± 1.11A
After Staining (t1) 81.32 ± 4.47AB -0.48 ± 1.28B 18.38 ± 3.23B
After cleaning (t2) 83.63 ± 4.21B -1.33 ± 1.06B 16.22 ± 2.34C

Group 4

CP + 0 min

Baseline (t0) 79.51 ± 6.06A 1.27 ± 0.42A 2.79 ± 1.65A
After Staining (t1) 83.00 ± 3.15AB -0.40 ± 1.34B 19.71 ± 3.77B
After cleaning (t2) 85.07 ± 2.62B -1.09 ± 1.03B 16.14 ± 3.09C

Group 5

CP + 5 min

Baseline (t0) 82.08 ± 9.42A 1.25 ± 1.01A 3.53 ± 1.21A
After Staining (t1) 84.22 ± 4.81AB -0.12 ± 1.55B 16.41 ± 4.10B
After cleaning (t2) 83.06 ± 3.16B -0.94 ± 1.09B 14.67 ± 3.64C

Group 6

CP + 10 min

Baseline (t0) 81.60 ± 6.13A 1.43 ± 0.53A 3.20 ± 1.36A
After Staining (t1) 81.86 ± 5.56AB 0.07 ± 1.48B 17.82 ± 3.76B
After cleaning (t2) 85.14 ± 3.41B -0.61 ± 1.11B 14.28 ± 3.37C

SD Standard deviation, ICC Invisalign Cleaning Crystals, CP Corega Proguard, 0 min No ultrasonic cleaning, 5 min 5 min of ultrasonic cleaning, 10 min 10 min of ultrasonic cleaning

Different uppercase superscript letters within the same group column indicate statistically significant differences over time based on Bonferroni pairwise comparisons