Clinical Research Associates

A. Research Questions

1. Do bleaches meet manufacturer's claims?
2. How many shade changes does each bleach lighten teeth?
3. Of the bleach products tested, do some perform better
than others?

B. Step-by-Step Procedures For In-House Clinical Evaluation

Materials & Procedures For In-House Clinical Evaluation:

a. Iodometric Assay (U.S. Pharmacopeia, USPXXII NFXVII, 1990 Carbamide Peroxide Assay pp 223)

Materials:

1 Burette 25cc - 50cc
1 Meniscus guide
1 Magnetic stir plate
3 Stir bars
1 Top loading balance accurate to .01g
3 250ml Iodine flasks with stoppers
1 Permanent marker
3 Timers/stop watches
3 Disposable weighing dishes
1 Spatula, micro weighing
Disposable 5 ml pipets
Pasteur Pipets
Rubber bulbs
Water squirt bottle
Burette Stand and clamp

Reagents:

Tooth whitening gel samples
Deionized water
Potassium Iodide, 99%
Sodium thiosulfate, 0.1N Volumetric standard
Ammonium Molybdate solution (10%)
Starch Indication solution
Glacial Acetic Acid

Procedure:

1. Record flask number in lab book.
2. Weigh out approximately 1.00 gram of gel into flask being careful to keep gel off walls of flask. Record weight in lab book.
3. Add 25ml of deionized water to flask. Add stir bar.
4. Add 5ml of glacial acetic acid to flask.
5. Place on magnetic stir plate and gently stir unitl gel has dissolved in solution.
6. Carefully add 2 grams of potassium iodide, gently mix.
7. Add 3 drops of ammonium molybdate solution and place in the dark for 10 minutes.
8. Fill burette with sodium thiosulfate and record height in ml using bottom of meniscus. Place flask onto stir plate and titrate with sodium thiosulfate until solution becomes a light straw yellow color.
9. Add 4 ml of starch indicator solution and continue to titrate to a colorless end point. Record the final end point.
10. Calculate the Carbamide Peroxide content by using the following formula: Volume of sodium thiosulfate used (ml) x 0.1N x 4.704 / weight of gel (grams).
11. Record data in lab book.
12. Repeat steps 1 - 11 until three results are obtained within 0.2% of each other. Average three results and record percent.

Materials:

1 Burette 25cc - 50cc
1 Meniscus guide
1 Magnetic stir plate
3 Stir bar
1 Top loading balance accurate to .01g
1 Permanent marker
3 50ml beakers
Water squirt bottle

Reagents:

Tooth whitening gel samples
Deionized water
Potassium Permanganate, .1 N Volumetric standard
Hydrosulfuric Acid, 2N

Procedure:

1. Record beaker number in lab book.
2. Weigh out 1.0 gram of gel into beaker. Record weight in lab book.
3. Add 20 ml of deionized water to beaker.
4. Add 20 ml of Hydrosulfuric Acid 2N and stir until gel has dissolved in solution.
5. Fill burette with potassium permanganate and record height in ml using top of meniscus.
6. Titrate gel solution immediately until solution turns a slight magenta/pink color. Each rapid turn of the buret knob should release only about 1 ml of potassium permanganate.
7. Record in lab book the final end point in ml.
8. Calculate the percent hydrogen peroxide using the following formula: 1.701 x 0.1N x Volume of potassium permanganate used (ml)/ gel weight (grams).
9. Record data results in lab book.
10. Repeat steps 1 - 9 until three results are obtained within 0.2% of each other. Average three results and record percent.

2. Taste Test

Materials:

23 bleach dispensers, one from each gel evaluated
1 Cup for each subject
Cotton tip applicators
Water
Sheet with grading criteria listed

Procedure:

1. Subject was seated and given grading criteria sheet. Using a cotton tip applicator a drop of bleach was applied to the maxillary central incisor (tooth #8).
2. Subject was asked to move gel to the gingiva and other teeth using their lips and tongue.
3. Subject ranked gel taste and texture according to the following scale:
Poor- Extremely offensive and intolerable taste and texture.
Fair- Mildly offensive, but tolerable taste and texture.
Good- Not offensive, taste and texture both good.
Excellent- Refreshing taste, and texture feels good.
4. A score was given between 1 and 4 based on the criteria, and scores were recorded (1=Poor, 4 = Excellent)
5. These steps were followed using 25 subjects.
6. The scores given for each gel were averaged.