Efficacy of GuruNanda® Teeth Whitening Strips – Express: An In-Vitro Evaluation of Dental Cleaning and Whitening Performance

An in-vitro evaluation of dental cleaning and whitening performance

Objective

The objective of this in-vitro evaluation was to determine the dental cleaning and whitening efficacy of GuruNanda® Teeth Whitening Strips – Express compared with a de-ionized water control, using a simulated extrinsic staining model on bovine enamel. The study measured differences in enamel lightness (L*) and color gradation (BG*) before and after treatment using a VITA Easyshade V colorimeter, following internationally accepted standards for dental material testing.

Process

Healthy bovine incisors were sectioned into enamel blocks (5 × 5 × 2 mm), embedded in resin, polished, and acid-etched. The specimens were stained for 48 hours in a standardized mixed-dye solution containing coffee, red wine, soy sauce, and black tea to simulate extrinsic discoloration.

The study consisted of two groups:

  • Test Group: GuruNanda® Teeth Whitening Strips – Express
  • Control Group: Filter paper soaked in de-ionized water

Each group included eight enamel blocks. Baseline measurements of lightness (L* before) and shade guide values (BG* before) were obtained using a VITA Easyshade V colorimeter. Each treatment involved a simulated 60-minute product contact, after which post-treatment readings (L* after, BG* after) were recorded. This procedure was repeated daily for 14 days, with enamel blocks stored in artificial saliva between sessions. Evaluation parameters included change in whiteness (ΔL* = L* after − L* before) and change in color gradation (ΔBG* = BG* after − BG* before). Statistical analyses were performed using paired and independent-sample t-tests (SPSS v26), with significance set at p < 0.05.

Results

Table 1. Change in Enamel Lightness (L*) Before and After Each Treatment

Day L* Value (A) ΔL* (A) L* Value (C) ΔL* (C) p-Value (A vs C)
0 44.08 ± 3.26 — 44.70 ± 2.80 — —
1 65.56 ± 5.53 21.49 ± 5.94 45.65 ± 5.64 0.95 ± 4.76 < 0.001
2 74.26 ± 5.79 30.19 ± 6.08 52.14 ± 5.65 7.44 ± 4.24 < 0.001
3 82.71 ± 2.59 38.64 ± 3.49 54.58 ± 4.13 9.88 ± 3.24 < 0.001
4 80.31 ± 6.62 36.24 ± 5.57 54.69 ± 6.17 9.99 ± 4.55 < 0.001
5 82.69 ± 5.98 38.61 ± 5.88 55.43 ± 4.97 10.73 ± 4.61 < 0.001
6 84.23 ± 4.44 40.15 ± 4.88 54.74 ± 6.52 10.04 ± 5.21 < 0.001
7 85.75 ± 3.91 41.68 ± 5.22 56.48 ± 5.42 11.78 ± 3.87 < 0.001
10 88.93 ± 2.79 44.85 ± 3.84 59.78 ± 3.65 15.08 ± 3.24 < 0.001
14 89.49 ± 3.05 45.41 ± 3.53 62.15 ± 4.79 17.45 ± 4.33 < 0.001

Figure 1. L* value represents brightness; higher values indicate whiter enamel. ΔL* denotes change in whiteness after each treatment interval.

Table 2. Change in Color Gradation (VITA Bleached Guide 3D-MASTER)

Day BG* (A) ΔBG* (A) BG* (C) ΔBG* (C) p-Value (A vs C)
0 29.00 ± 0.00 — 29.00 ± 0.00 — —
1 28.75 ± 0.71 −0.25 ± 0.71 29.00 ± 0.00 0.00 ± 0.00 < 0.001
2 20.00 ± 5.01 −9.00 ± 5.01 29.00 ± 0.00 0.00 ± 0.00 < 0.001
3 14.38 ± 3.20 −14.63 ± 3.20 28.88 ± 0.35 −0.13 ± 0.35 < 0.001
4 13.25 ± 4.74 −15.75 ± 4.74 28.50 ± 1.07 −0.50 ± 1.07 < 0.001
5 12.13 ± 4.52 −16.88 ± 4.52 28.63 ± 1.06 −0.38 ± 1.06 < 0.001
6 10.25 ± 3.28 −18.75 ± 3.28 28.50 ± 1.07 −0.50 ± 1.07 < 0.001
7 9.38 ± 2.67 −19.63 ± 2.67 28.38 ± 1.06 −0.63 ± 1.06 < 0.001
10 6.00 ± 2.27 −23.00 ± 2.27 28.13 ± 1.36 −0.88 ± 1.36 < 0.001
14 5.25 ± 1.83 −23.75 ± 1.83 27.88 ± 1.73 −1.13 ± 1.73 < 0.001

Figure 2. BG* value progression over 14 days. Smaller BG* values indicate whiter enamel. ΔBG* represents change in color gradation.

Figure 3. Comparative whitening performance of GuruNanda® Teeth Whitening Strips – Express versus control: visual progression of enamel brightness across 14 days.

Observation

GuruNanda® Teeth Whitening Strips – Express demonstrated statistically significant whitening activity, producing visibly brighter enamel blocks after a single simulated use. A ΔL* exceeding 21 points indicated substantial color improvement compared to the control (p < 0.001). Over the 14-day study period, incremental increases in L* and decreases in BG* values confirmed a cumulative whitening effect. Visual inspection corroborated instrumental findings, showing noticeable brightening after each application.

Conclusion

This in-vitro evaluation confirmed that GuruNanda® Teeth Whitening Strips – Express deliver high cleaning and whitening efficacy, effectively removing extrinsic stains and increasing enamel lightness without compromising surface integrity. The significant increase in L* values and decrease in BG* values highlight its rapid whitening potential. These results support its use as a safe, enamel-friendly, and fast-acting whitening solution suitable for express applications or ongoing maintenance.