Science Research Project. Dental Whitening and Enamel Loss

Transcription

1 Science Research Project 2015 Dental Whitening and Enamel Loss

2 Introduction The solid part of the tooth consists of 3 main parts; 1. Dentine or the tooth bone, forms the largest portion 2. Enamel which covers crown portion of the tooth is above the gum 3. Cementum the thin layer on the root, the portion that is below the gum. Tooth Enamel Enamel is the outer coating of the tooth. It can be worn down by excessive scrubbing or acidic foods. The best protection for enamel is fluoride. The enamel is the hardest compact part of the tooth and is make up of 96.5% of inorganic matter (lime and magnesium phosphates, traces of calcium and fluoride, carbonite of lime and salts) and 3.5% of organic matter. Figure 2 The structure of the human tooth Things we eat and put in our mouths over years gets into the porous enamel layer of the tooth and cannot be brushed or scoured away. These types of stains on a tooth are usually considered harmless but many people find them unattractive. Erosion On the other hand, erosion occurs when the enamel is dissolved from the tooth s surface. Excessive eating of certain foods and drinks, containing acid, causes the enamel surface of the tooth to erode. Saliva in the mouth is meant to dilute or clean away foods and acids naturally from the teeth but when high levels of acid are present, this system can no longer keep up and acid erosion can occur. Brushing or scouring the tooth s surface when acid is present increases the eroding effect on the enamel. Whitening Toothpastes In Australia, 92% of toothpastes are made by, Colgate-Palmolive and GlaxoSmithKline. These two major companies are responsible for the hundreds of oral products on the store shelves. Tooth-whitening products are the largest segment in the oral care market. Common ingredients of whitening toothpastes include fluoride and an abrasive (which helps the paste retain moisture) and sweetener as well as water, flavour and a lathering agent. Few contain a bleaching agent which is required to physically alter the colour of teeth. Extract from the Australasian Dentist Magazine Many dental whitening products attack enamel, causing dissolution of the surface enamel and exposing a porous surface This investigation sought to explore the relationship between whitening toothpastes and nonwhitening toothpastes and; i) ph ii) change in tooth width with toothpaste use iii) change in whiteness Some toothpastes that contain Stannous (Tin II) Fluoride which has proven to prevent enamel erosion 88% better than Sodium Monofluorophosphate Na 2PO 3F. Although the ph of SnF 2 is lower than 7, the acidic effect works by the formation of Calcium Fluoride crystals on the surface

3 of the enamel. This then becomes soluble in the next acid attack which forms the ability of remineralisation due to the rich content of fluoride in the surrounding solution. This study incorporated five toothpastes, three whitening and two non whitening. Ten teeth were used, two with each type of toothpaste. The study was conducted over a period of twenty one days.

4 Abstract, Aim and Hypothesis Abstract The aim of the experiment was to determine whether whitening toothpastes have a lower ph than non-whitening toothpastes, whether whitening toothpastes whiten teeth more than nonwhitening toothpastes and whether whitening toothpastes cause a greater loss of dental enamel than non-whitening toothpastes. In total 10 molar teeth, 3 whitening and 2 non-whitening toothpastes were used. Each of the toothpastes was used to brush two different teeth daily for 21 days. In between brushing, the teeth were soaked in saline solution so as to replicate the conditions of the oral environment. Each tooth was marked to indicate where the caliper was to be placed for taking measurements on days 0, 11 and 21. Images of the teeth were taken under a microscope before and after testing. A tooth colour shade guide was used to determine the colour of the teeth on days 0, 11 and 21. The whitening toothpastes produced significant changes in tooth whiteness with the nonwhitening toothpastes bringing about no change. The ph measurement showed no relationship between toothpaste types. However, the Oral B Original Toothpaste proved acidic due to the ingredient called Stannous Fluoride. The results showed that all the whitening toothpastes caused the more loss of dental enamel than the non-whitening toothpastes. The White Glo whitening toothpaste caused the most erosion of enamel. Both non-whitening toothpastes caused no erosion. Aim To determine if; a) A loss of dental enamel occurs more when using whitening toothpastes than when using non-whitening toothpastes b) The ph is lower in whitening toothpastes than non-whitening toothpastes c) Whitening toothpastes improve whiteness more than non-whitening toothpastes Hypothesis Whitening toothpastes cause greater loss of dental enamel, improve whiteness and have a lower ph than non-whitening toothpastes.

5 Risk Assessment Step 1 Identify the Hazard CSIS User code (for chemical s only) Step 2 Strategies to minimize the hazard Step 3 Assessment of risk (see table below) Step 4 What if something goes wrong? Step 5 Packing up Unsterilised teeth can be health hazard to those handling N/A Use gloves and sterilise teeth before handling by soaking in bleach for 24 hours 2+1=3=Moderate Wash hands immediately and consult doctor if irritation occurs Wipe down bench and or anything that has come into contact with teeth Electronic caliper is slightly sharp and may cut skin N/A Keep electronic caliper away from the edges of benches and away from contact of sharp edges with skin 2+1=3=Moderate Seek first aid if required Pack away carefully Glass may break and cut skin Pumice may be inhaled when used with the polishing lathe or get into eyes Curing Light will cause retinal N/A N/A N/A Place glassware away from edges of benches and keep outside dry to minimise slipperiness Wear a facial mask and safety glasses Avoid looking directly into light and 1+2=3=Moderate 2+2=4=Moderate 4+1=5=Moderate In case of breakage consult adult. Empty glassware, brush up and place in broken glass bin. Wipe up any spills. SKIN: If cuts occur, seek first aid Wash eyes with water and/or seek medical attention if coughing pursues Seek Medical attention as Pack away carefully Wipe down any remaining pumice off benches and equipment Ensure the device is turned off

6 damage if the operator looks directly into light always wear UV radiation protection glasses soon as possible before replacing it into its case Dental UV curing light will damage teeth if too hot (usually applies to older models) N/A Hold the curing light about 3mm away from a finger and if your finger gets too hot then it could do damage to teeth 2+1=3=Moderate If the UV light becomes too hot, do not use on teeth. Ensure the device is turned off before replacing it into its case Mandatory precautions: Covered shoes, safety glasses, hair exceeding shoulder length tied back A. What is the potential impact or consequence of the hazard? B. What is the likelihood of the event happening? Add numbers in columns A and B together How to assess the risk Action 1 = MINOR First aid required with little or no time lost 1 = LOW If could happen but only rarely 1 2 = LOW RISK Proceed with caution 2 = MODERATE Medical treatment required, some lost time 2 = MODERATE It could happen occasionally 3 4 = MODERATE Consult with teacher 3 = SERIOUS Medical treatment required, extended lost time 3 = HIGH It could frequently happen 5 6 = HIGH Reassess the need to perform the practical/consult with teacher

7 Equipment Quantity Equipment 10 *Extracted Sterilised Teeth 2L Gelflex Saline Solution 10 Small Rectangular containers (8cm x 4.5cm x 1.5cm) 200mL 3M Transbond Plus Band Cement Dental Adhesive paste 1 Plastic spatula 12 50mL beakers 1 Global G6 Surgical microscope (19x magnification with built in camera) 1 Electronic Caliper LCD Vernier Micrometer 30mL Renfert Die Dental model hardener liquid 1 Generic Calico Cloth Mop Rotating Polisher 1 Generic Small Calico cloth polishing lathe 1 SDI Radii Plus Curing Light 1 Data logger 2 ph indicator probe data logger attachment 110g (W1) Colgate Optic Whitening toothpaste (commercially sold) 95g (W2) Oral B 3D White Whitening toothpaste (commercially sold) 150g (W3) White Glo Whitening toothpaste (commercially sold) 40g (T1) Colgate Original Toothpaste (commercially sold) 40g (T2) Oral B Original Toothpaste (commercially sold) 1 Camera 1 Permanent Marker 1 Metal Spatula *Please note that the patients have given permission for their already extracted teeth to be used in this Science Research Project however they wish to remain anonymous.

8 1 Safety Glasses 1 UV light protection glasses 1 Large rubber bowl 1 Roll of paper towels 1 Oral B Electric Toothbrush with timer and pressure control 10 50mL small round containers 1 cup Pumice (volcanic rock powder used with polishing machine) 1g 37% Phosphoric Generic Dental Etch 1 Apron 1 Oral B Dental Whitening shade guide 1 Electronic mass scale 5 Small watch glass 1 Pen 500mL Distilled water 2 Stirring rod 1 Measuring cup (1 cup) 1L Tap Water 6 cups Heraus Gypsum Dental Stone Power 1 Nikon Coolpix x990 camera with macro lens 1 Permanent Marker 1 Micro Brush 1 Pencil 300mL Bleach 1 Dental Probe *Please note that the patients have given permission for their already extracted teeth to be used in this Science Research Project however they wish to remain anonymous.

9 Method Preparation of Teeth Samples: 1. All ten teeth samples were sterilised for hygiene purposes by being soaked in a beaker of bleach solution for 24 hours. 2. One cup of pumice powder and three quarters of a cup of water were mixed together in a rubber bowl. 3. The surface of the tooth that needed to be polished was placed against the tiny frayed edges of the cloth mop. 4. A small amount of the pumice and water mixture was placed on top of the tooth and the rotating polishing cloth mop was turned on to the high speed setting. The pumice was continuously pushed in between the tooth and the cloth mop while it was rotating. Only the rounded/circumference sides of the tooth were polished. 5. To determine if the tooth was polished the pumice was then washed off the tooth and held up to a light. If any dull abraded surfaces were present, step 4 was repeated. 6. Steps 3 and 4 were repeated for the remaining nine teeth. 7. The teeth were then washed and placed in a container of saline. Pumice Small Calico Cloth Polishing Lathe Figure 2 Tooth being polished against the calico rotating polishing cloth mop Tooth Figure 3 Diagram showing the sides of the tooth polished Only the rounded tooth surface was polished (above the line)

10 Method Identification and handling of teeth: 8. Half a cup of dental stone powder was placed into a large rubber bowl. 9. A small cup filled with tap water was gently trickled into the centre of the bowl while the mixture was stirred using a long plastic spatula. 10. When the mixture became a thick but smooth texture (similar to that of custard) no more water was poured in and the mixture was poured into a small rectangular mold. The mold was then tapped onto a hard flat surface until all the air bubbles had been removed. 11. After 1 to 2 minutes, the tooth was inserted into the centre of the dental stone which had already begun to set. The tooth was inserted root first until only 4-6 millimetres of the tooth s root (from under the gum line) remained visible. 12. Steps 8 to 11 were repeated for the remaining nine teeth. 13. After about 45 minutes the stones had fully set and was removed from the rectangular lids. (Fig. 5) 14. Dental model hardener liquid was then painted on the entire surface of the stones using a small brush ensuring that the liquid did not come into contact with the tooth. (Fig. 6) 15. After the surfaces of the dental stone had dried, each of the stones were randomly selected and labelled for identification purposes. Non-Whitening T1A Colgate Original Toothpaste Tooth A T1B Colgate Original Toothpaste Tooth B T2A Oral B Original Toothpaste Tooth A T2B Oral B Original Toothpaste Tooth B Whitening W1A Colgate Optic White Toothpaste Tooth A W1B Colgate Optic White Toothpaste Tooth B W2A Oral B 3D White Toothpaste Tooth A W2B Oral B 3D White Toothpaste Tooth B W3A White Glo Whitening Toothpaste Tooth A W3B White Glo Whitening Toothpaste Tooth B Semi Dried Dental Stone Tooth Figure 4 Tooth inserted into semi dried dental stone and left to dry for around 45 minutes Figure 5 Dental Stone painted with Dental model hardener liquid to prevent any cracks or breakages in the stone Figure 6 Stone removed from lid and randomly selected and labelled

11 Method Dental Adhesive: 16. The dental etch was placed on the surface of the tooth where the adhesive was intended to go. It remained there for 10 to 20 seconds and afterwards, the dental etch was washed off beneath a tap. 17. The tooth was dried and adhesive was placed onto the tooth. (Figure 7) 18. A dental probe was used to ensure that the edge of the dental adhesive was straight on the peak convexity of the rounded surface of the tooth (cusp) (Fig. 8) 19. A curing light was then used to dry the dental adhesive to the tooth. (Fig. 9) 20. Steps 16 to 19 were repeated for the remaining teeth. Figure 7 Applying adhesive to the etched surface of the tooth Figure 8 Dental probe being used to create a straight line of the dental adhesive to enable accurate measurements using a caliper Dental probe ensured that the adhesive was straight Figure 9 Curing light used to cure the dental adhesive to the tooth UV light is extremely strong and must be looked at through UV protection glasses Peak Convexity of tooth cusp Figure 10 Diagram illustrating the peak convexity of the tooth cusp where the dental adhesive was placed

12 Method Documentation of the enamel surface of the teeth: 21. Each tooth was photographed under a microscope (an operating surgeon s microscope, 19x magnification with built in camera). Each tooth was photographed from both the side views off the tooth (showing adhesive) (Fig. 11) 22. Using a Nikon Coolpix 990 camera with a macro lens, photos were taken of each tooth and the matching shade on the guide. The matching shade number was recorded for each tooth. (Fig. 12) 23. A pencil marking was made on both the tooth and stone on the intended measurement spot to ensure that all measurements were accurate. (Fig. 13) 24. The electronic caliper was used to measure the width of each tooth. The dental adhesive and pencil markings on the tooth and the plaster were used as a guide to measuring from the exact same spot each time. (Fig. 14) 25. Step 23 & 24 was repeated 5 times for each tooth. Figure 11 Photo taken of side view of tooth showing dental adhesive Figure 12 Each tooth was photographed using the Nikon camera. The shade guide was positioned above the tooth to show the colour Figure 13 Pencil marking made on both tooth and stone for future measurements Figure 14 Measuring the width of the tooth using an electronic caliper

13 Method Testing the ph of the Toothpastes: 26. Using a spatula, 1g of toothpaste was dissolved in 25mL of distilled water in a 50mL beaker. (Fig. 15) 27. Using two different ph probes attached to a data logger, the ph level of the 25mL solution was measured twice with each probe by placing in the centre of the solution. (Fig. 16) 28. After each measurement, the probe used was washed with distilled water. 29. Steps 26 and 28 were repeated for the rest of the toothpaste solutions. Figure 15 Toothpastes allocated to a 50mL beaker Probe 1 (in use) Probe 2 Figure 16 ph probe dipped into the centre of the stirred solution and the ph was recorded

14 Method Testing: 30. Each tooth was placed upside down in a small round container filled with saline solution 24 hours before the start of the experiment. (Fig. 17) 31. Twice a day, each tooth was removed from the saline and brushed for a total of 20 seconds with its assigned toothpaste. One side (with the adhesive) was brushed for 10 seconds and the same was repeated on each side (with the adhesive). 32. When brushing teeth, the electric tooth brush attachment would time how long you have brushed the teeth for and also ensure you aren t brushing the teeth too hard. (A warning sign would appear once you pressed too hard with the tooth brush) (Fig.18) 33. The teeth were then submerged in the saline solution in between applications of the whitening and non-whitening toothpastes. 34. This testing was repeated for 21 days. 35. The containers of saline were washed out and replaced every 5 days. Figure 17 Saline is squirted into a small round container the tooth is then placed upside down into the saline Figure 18 When too much pressure is placed on the tooth with the brush, a warning sign appears on the timer

15 Method Mid-Testing Measurements Day 11: 36. Steps 22 and 24 were repeated on day 11. Measuring Findings Day 21: 37. Using a Nikon Coolpix 990 camera with a macro lens, photos were again taken of each tooth and the matching shade on the guide. The matching shade number was recorded for each tooth. 38. The electronic caliper was used to re-measure the width of each tooth from one exact point to the other, each time. 39. Dental adhesive and pencil markings on the tooth and the plaster were used as a guide to measuring from the exact same spot each. 40. The dental adhesive was then removed from the tooth using a hand scaler 41. After day 21, each tooth was photographed under a microscope (an operating surgeon s microscope, 19x magnification with built in camera). Each tooth was photographed 4 times. i) Before the removal of the first adhesive ii) After the removal of the first adhesive iii) Before the removal of the second adhesive iv) After the removal of the second adhesive. 42. The images of the teeth were compared with those taken on day 0 for signs of enamel abrasion.

16 ph Results ph of 1g toothpastes dissolved in 25mL of Distilled Water ph Toothpaste Probe Trial 1 Trial 2 Avg. ph T1 A B T2 A B W1 A B W2 A B W3 A B

17 Tooth Measurements Tooth Width Measurements on day 1, 11, 21 for teeth brushed daily using Non- Whitening toothpastes Tooth Width (mm) Toothpaste Trial Day 0 Day 11 Day 21 T1A Avg Tooth Variance 0.000% T1B Avg Tooth Variance 0.000% T2A Avg Tooth Variance % T2B

18 Avg Tooth Variance % Tooth Width Measurements on day 1, 11, 21 for teeth brushed daily using Whitening toothpastes Tooth Width (mm) Toothpaste Trial Day 0 Day 11 Day 21 W1A Avg Tooth Variance % W1B Avg Tooth Variance % W2A

19 Avg Tooth Variance % W2B Avg Tooth Variance % W3A Avg Tooth Variance % W3B Avg Tooth Variance %

20 Tooth Shade Tooth shades over duration of testing Tooth Tooth Shade Lightest Shade Darkest Shade B1 A1 B2 D2 A2 C1 C2 D4 A3 D3 B3 A3.5 B4 C3 A4 C4 Shades Lighter T1A T1B T2A T2B EMS No change EMS No change EMS No change EMS No change W1A E M S 7 W1B E M S 6 W2A E M S 4 W2B E MS 4 W3A EM S 6 W3B E M S 3 E = End M = Mid-way S = Start

21 Pictorial Evidence of Abrasion Tooth Time (Day) Colour Chart Photo Microscope Photos T1A Day 0 Day 11 Day 21 T1B Day 0 Day 11 Day 21 T2A Day 0 Day 11

22 Day 21 T2B Day 0 Day 11 Day 21 W1A Day 0 Day 11 Day 21 W1B Day 0 Day 11

23 Day 21 W2A Day 0 Day 11 Day 21 W2B Day 0 Day 11 Day 21 W3A Day 0 Day 11

24 Day 21 W3B Day 0 Day 11 Day 21

25 Discussion The majority of the data presented within the results supports the hypothesis that whitening toothpastes cause greater loss of dental enamel and improve whiteness. The ph measurements showed no relationship between toothpaste types and there was no distinct pattern regarding the ph of whitening and the ph of non-whitening toothpastes. The repeat ph tests were consistent and therefore the measurements are reliable. These results do agree with the secondary source article from the Indian Society of Periodontology. This article was written about a clinical study proven that an acidic toothpaste containing Stannous (Tin II) Fluoride prevents enamel erosion and remineralises the teeth. The average percentage loss of dental enamel was greater on the teeth that were tested with the whitening toothpastes. Both non-whitening toothpastes had a 0% loss of tooth enamel compared to the whitening toothpastes which ranged from 0.7% (Oral B 3D White Test A) to 1.2% (White Glo Test B) loss of enamel. The results of the White Glo Whitening Toothpaste in both tests indicate that it created the largest loss of dental enamel compared to the other two whitening products tested, with an overall percentage loss of 1.1%. The results in both tests for Oral B 3D White whitening toothpaste showed the lowest average percentage of 0.7% enamel loss in comparison to the other two whitening products. A visual method of identifying enamel loss was also performed. Under magnification the enamel surface of the tooth was viewed looking for any evidence of enamel loss (unsmooth surfaces) on the unprotected surfaces of the tooth. This was identified in one whitening toothpaste mainly Colgate Optic whitening toothpaste. The comparison of texture was observed between the originally prepared polished surfaces to the abraded surface. Again the dental adhesive was used as a protective layer on the enamel. At the end of testing, signs of unsmooth surfaces were found in the teeth tested with the whitening toothpastes and showed the removal of surface texture demonstrating a loss of dental enamel had occurred. This agrees with the findings of the caliper measurement results. In between brushes, the teeth were soaked in saline in to attempt to replicate the oral environment. Saliva substitutes were difficult to locate and were costly. Keeping the teeth in saline also prevented them from discoloring due to desiccation therefore allowing valid colour results. Visual examination of the colour of the teeth using a shade guide was undertaken and when compared to the colour at the end of the testing both tests showed similar results. The non-whitening toothpastes had no change in colour and the results show that whitening toothpastes had a colour change, ranging from 3 to 7 shades lighter across the three products. The results of the Oral B 3D Whitening

26 Toothpaste in both tests indicate the least effective in whitening the tooth colour compared to the other whitening products used. This whitening toothpaste while resulting in the least whitening effect it also caused the least loss of enamel on the tooth. The results indicated that the Colgate Optic White and White Glo whitening toothpastes had quite similar whitening results. The White Glo whitening toothpaste was effective in whitening the teeth it was also the most abrasive causing the most enamel loss on the tooth. The results from both tests of every toothpaste proved reliable in determining the accuracy of the results as they both reflected similar results with an acceptable margin of error. The measurements for the loss of enamel was accurate because the size of the tooth was measured with the electronic caliper 5 times with producing similar results. Teeth generally possess irregularities on the enamel surface on the lateral sides and also have a curved surface. This makes it difficult to determine the exact dimensions of the tooth. To ensure accuracy in the measurements, a sensitive electronic caliper was used and the tooth s surface was polished before testing to remove surface irregularities to a certain extent. Dental adhesive was used as a location marker on the tooth (as well as for a visual surface comparison of abrasion) to ensure the caliper was placed into and measured the same point each time. The dental adhesive also improved the accuracy of the measurements because it created an indication for where the electronic caliper was placed when taking repeated measurements. An electronic toothbrush with a pressure control timer on it enabled the experiment to remain controlled. Although the same pressure was attempted to be maintained, it is almost impossible to control exactly the same pressure the entire process. Differences in pressure can cause different abrasive affects and this is indeed a limitation of the experiment. There are several areas of possible improvement within the experiment and method. One of these would be, if given more time, to lengthen the experiment by another three weeks as it appears that whitening toothpastes continue to remove dental enamel. Access to more teeth, would enable the investigation to be performed using a different range of non-whitening toothpastes. Due to the cost, other whitening methods such as whitening strips and dental whitening kits were not used in this experiment. Alterations to the method would include measuring each tooth with the caliper from different angles and sides of the tooth. Overall, the White Glo Whitening Toothpaste proved to be the most abrasive of tooth enamel when brushed into teeth twice a day for 21 days.

27 Conclusion The three whitening toothpastes, did whiten teeth more than the two non-whitening toothpastes tested. The three whitening toothpastes caused a significantly greater loss of the dental enamel than the two non-whitening toothpastes. Acknowledgements Jo-anne McGrouther (Teacher) - Provided guidance regarding the proposed aim and method of the experiment - Assisted in the editing and made improvements of report - Gave advice regarding ph testing, i.e. advised the use of distilled water when testing the ph of the toothpastes - Provided encouragement over the course of the project Dr. Clem Maloof (Dental Practitioner) - Provided access to all dental equipment and products used in experiment - Advised the proper use of the machinery and tools to ensure safety and correct usage - Provided the 10 teeth samples - Provided financial support, i.e. purchased the toothpastes and electronic toothbrush

28 Bibliography 1. Choice.com.au,. 'Toothpaste Marketing'. N.p., Web. 10 Feb 'Does Dental Whitening Result In Calcium Loss In Enamel?'. Australasian Dentist, Author Unstated November December (2015): 74, 75. Print _001.jpg, Healthwise Incorperated Print. 4. Toothpaste. 1st ed. David A. Katz, Web. 11 Feb Brand, Richard W, and Donald E Isselhard. Anatomy Of Orofacial Structures. Print. 6. 'A Randomised Clinical Study To Measure The Anti Erosion Benefits Of A Stannous Containing Sodium Fluoride Dentifrice'. Indian Society of Periodontology 19.2 (2015): Print.