Name: __________________________Date: ____________Period



Name: __________________________Date: ____________Period: _________

Toothpaste Lab

Purpose: To discover the best working toothpaste.

Background Information: Baking Soda is a weak base. Adding it to toothpaste should raise the pH of toothpaste and inhibit the growth of bacteria that flourish in a slightly acidic environment and cause tooth decay. People expect to see foam when they brush their teeth, so foaming agents are added.

Toothpastes claim to clean, remove plaque, prevent cavities, and whiten teeth. Is there really a difference in toothpastes? Is one truly superior to another? Does a higher price mean a toothpaste is better?

Teeth are the calcified structures in our mouths that are used to break down food. Teeth are made of multiple tissues of varying density and hardness. The two major parts of a tooth are the crown and the root. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by our gums. The crown is the visible portion that extends above the gums. The crown is covered by a glossy, white, hard coating called enamel. Enamel is composed primarily of the mineral hydroxylapatite, which is a crystalline calcium phosphate. The enamel is the hardest substance in the human body, but is it brittle, subject to injury, and can also be worn down by abrasive action or acidic foods.

Almost immediately after a thorough cleaning, a thin, biofilm called the pellicle begins to coat the teeth, gums, and tongue. Pellicle is derived from proteins in saliva. Bacteria, along with stains from food and drink, collect on the pellicle forming a gel-like material called plaque. The bacteria in the plaque ferment the sugars and starches in foods to produce lactic acid which dissolves the calcium and phosphorus in the tooth enamel. When enough demineralization occurs, bacteria can enter the dentin and cause decay. Tooth decay or cavities are known as dental caries.

Plaque can seep below the gumline and cause a mild gum disease called gingivitis resulting in gum inflammation. Within 2 to 14 days of plaque formation, the plaque deposits will bond with minerals in the saliva to form a calcified deposit called calculus, more commonly known as tartar. The calcified tartar can only be removed by professional cleaning.

Oral hygiene is the practice of keeping the mouth clean and is a means of preventing dental caries, gingivitis, periodontal disease, bad breath, and other dental disorders. It consists of both professional and personal care. Healthcare professionals recommend regular tooth brushing at least twice a day (morning and evening) and after meals. A toothbrush is able to remove most plaque, except in areas between teeth and raises the pH of the tooth surface neutralizing acids. Flossing is also considered a necessity to maintain oral hygiene. When used correctly, dental floss removes plaque from between teeth and at the gum line, where periodontal disease often begins and could develop caries.

Regular cleanings, usually done by dentists and dental hygienists, remove tartar that may develop even with regular brushing and flossing. Professional cleaning may also include tooth scaling, which uses various instruments to remove deposits from teeth.

Toothpaste is a paste or gel dentifrice used, with a toothbrush, to clean and maintain the aesthetics and health of teeth. Toothpaste serves as an abrasive that aids in removing the dental plaque and food from the teeth, assists in suppressing halitosis, and delivers active ingredients such as fluoride or xylitol to help prevent tooth and gum disease.

Toothpastes are complex mixtures of abrasives and surfactants; anticaries agents, such as fluoride; tartar control ingredients, such as tetrasodium pyrophosphate and methyl vinyl ether/maleic anhydride copolymer; pH buffers; humectants (to prevent dry-out and increase the pleasant mouth feel); and binders, to provide consistency and shape. (See Table 1). Binders keep the solid phase properly suspended in the liquid phase to prevent separation of the liquid phase out of the toothpaste. They also provide body to the dentifrice, especially after extrusion from the tube onto the toothbrush.

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Table 2 lists typical ingredients used in toothpaste formulations; the final combination will depend on factors such as ingredient compatibility and cost, local customs, desired benefits, and quality to be delivered in the product.

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Pre-lab questions:

1. Define dentifrice: _____________________________________________________________

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2. Define halitosis: ______________________________________________________________

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3. Define surfactant: _____________________________________________________________

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4. Why are humectants used in toothpastes? _________________________________________

_____________________________________________________________________________

_____________________________________________________________________________

5. Choose two different toothpastes, one of them must contain baking soda. Write their names and ingredients below:

|Toothpaste’s Name: (Section B) |Toothpaste’s Name with baking soda: |Toothpaste’s Name: |

| |(Section C) |(Section D) |

| | |Vanderwood’s Clean Em Up |

|Ingredients: |Ingredients: |Ingredients: water, glycerin, baking |

| | |soda, salt |

Lab Results:

Record all results on the Report Sheet. See attached paper.

SAFETY PRECAUTIONS:

• Wear goggles or safety glasses at all times in the laboratory.

• There are no health hazards associated with any of the substances used in this experiment.

• Do not taste or put into your mouth any of the toothpastes used during this experiment.

DISPOSAL:

• All solid substances used in this experiment can be disposed of in the trash can.

• All liquid substances used in this experiment can be disposed of in the sink or trash can.

PROCEDURE PART 1:

A. Preparation of toothpaste solutions for testing

• Weigh about 0.5 g of toothpaste into the plastic vial with a cap. Label your vials with your name and the toothpaste’s name.

• Add 10 mL of water to the vial. Turn vial upside-down then right-side up 20 times.

• Place the vial on the lab table and let sit for 15 minutes.

• Repeat this procedure for each sample of toothpaste you are testing. You are testing 3 different samples.

• Save these solutions for use in parts B and C in the procedure below.

B. Determination of foaming ability

• After the vial has sat for 15 minutes, measure the height of the foam above the water in mm. The foaming ability is the height of the foam (in mm) above the water.

• Remember that 10 mm = 1 cm

C. Determination of pH

• Be sure to record the foaming ability measurement before doing this step! (You can move on to steps D and E as you wait.)

• Measure the pH of each solution contained in your plastic vials using a pH meter. Be sure to thoroughly rinse the pH meter after each solution tested.

D. Determination of hard and sharp edged abrasive particles

• Squeeze a small amount of toothpaste onto your finger.

• Using another finger, squeeze and rub the toothpaste between your fingers to test for the presence of hard and sharp edged abrasive particles.

• Record your observations. Rate on a scale of 1-5 with 1 being very smooth to 5 being gritty.

• Repeat this test for each sample of toothpaste you are using.

E. Determination of Spreadability

• Measure about 1 g of toothpaste onto the center of a watch glass.

• Stack a second watch glass over the sample in the same orientation. (You are basically making a watch glass sandwich with toothpaste in the center.) Be careful to avoid sliding of the plate.

• Set the watch glass contraption on the lab table then place a filled 500mL water bottle on the top watch glass.

• After 1 minute, remove the water bottle and measure the diameter (in mm) of the toothpaste.

• Repeat this test for each sample of toothpaste you are using.

PROCEDURE PART 2:

F. Cleaning Ability

• Note: In the procedure below, you will test the cleaning ability of 3 different toothpastes on the shell of the stained egg.

• Using a permanent marker, divide (and label) the eggshell into four equal parts like this:

• These will be the areas of the egg that you will be cleaning; one area for each toothpaste tested as well as one control group area.

• It is very important to use the same method of testing for each toothpaste otherwise you will introduce other variables into your experiment. Make sure to use the same number of brush strokes while testing each toothpaste. We recommend using 15 brush strokes, but your group may decide to use more brush strokes, if necessary, to obtain results. Just make sure to use the same number of brushstrokes for each toothpaste tested! (This is a comparison of cleaning ability, so do not use excessive brushing!) To allow for a proper comparison of results, repeat the brushing procedure as exact as possible for each toothpaste tested.

• You will record your observation by rating the cleaning ability on a scale of 1-5 with 1 being "didn't clean" at all to 5 being "like a brand new egg."

• Section A: (control group with no toothpaste)

o Moisten a toothbrush with water and shake off any excess water.

o Brush a portion of section A on the egg with the damp toothbrush for 15 strokes. (One brushstroke is considered one complete back and forth motion).

o Inspect the egg to see if any color is removed and record your results.

• Section B: (One chosen toothpaste without baking soda)

o Rinse the toothbrush with water, shake of the excess water, and place a pea-sized amount of a toothpaste of your choosing on the brush.

o Brush a portion of section B on the egg with the toothpaste for 15 strokes (the same number of strokes you used previously.)

o Rinse the egg and the toothbrush and record your results.

• Section C: (Another chosen toothpaste with baking soda)

o Rinse the toothbrush with water, shake of the excess water, and place a pea-sized amount of your 2nd chosen toothpaste on the brush.

o Brush a portion of section B on the egg with the toothpaste for 15 strokes (the same number of strokes you used previously.)

o Rinse the egg and the toothbrush and record your results.

• Section D: (Esperanza Toothpaste of baking soda, water, and salt)

o Rinse the toothbrush with water, shake of the excess water, and place a pea-sized amount of the Esperanza toothpaste on the brush.

o Brush a portion of section B on the egg with the toothpaste for 15 strokes (the same number of strokes you used previously.)

o Rinse the egg and the toothbrush and record your results.

Name:_________________________________________ Per:___ TOOTHPASTE LAB

Post-lab questions:

1. a) Which toothpaste was the most abrasive?

b) Which was the least abrasive?

2. How did abrasiveness relate to cleaning ability? Explain at least 2 pieces of evidence from your experiment to support your answer.

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3. List the toothpastes in order from highest pH (most alkaline) to lowest pH (most acidic).

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4. a) Which toothpaste exhibited the most foaming ability?

b) Which toothpaste exhibited the least foaming ability?

5. How did the foaming results relate to the cleaning ability of the toothpaste? Explain at least 2 pieces of evidence from your experiment to support your answer.

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6. a) Which toothpaste exhibited the greatest cleaning ability?

b) Which toothpaste exhibited the least cleaning ability?

7. Can you attribute cleaning ability to any specific ingredients in the toothpaste? (Explain.)

8. Compare the ingredients in the commercial toothpastes you tested. Is there any significant differences in the toothpastes? (Explain.)

9. Which toothpaste had the most spreadability and explain why this may be important?

10. In your opinion, which of the two commercial toothpastes was the best value? (Explain.)

11. Conclusion: On a separate piece of paper, write a paragraph or two explaining what you learned from this lab. Be sure to address the results of your experiment to support your findings.

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