(student research, class projects)
Students can research and debate the mercury-in-amalgam fillings issue. Anti-amalgam groups abound online. Here is one set of documents said to support the anti-amalgam position: http://www.flcv.com/dams.html. Here is another: http://www.thenaturalrecoveryplan.com/research.php. Students must be made aware of the bias inherent in some of these sites. Pro-amalgam positions include the ADA http://www.ada.org/en/about-the-ada/ada-positions-policies-and-statements/statement-on-dental-amalgam), the FDA (http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/DentalProducts/DentalAmalgam/ucm171094.htm) and FDI World Dental Federation (http://www.fdiworldental.org/media/11351/Safety-of-dental-amalgam-2007.pdf). It is enlightening to see how one group can cite specific scientific studies that support its position, while the group espousing the opposite position uses the same study to support their position. (reminiscent of global warming, er … I mean, climate change) Wikipedia’s page on the dental amalgam controversy can be found here: https://en.wikipedia.org/wiki/Dental_amalgam_controversy.
Also see “Web Sites for Additional Information” below for more sites on amalgam fillings.
Students can research and debate the fluoride treatment issue.
Students might be able to obtain teeth from their dentist on which to do long-term research re: dental caries formation and prevention.
Students can research and report on other equilibrium systems at work in the body.
Students can research and report on acidic and basic foods and their effects on tooth erosion/decay.
Students can research and report on types of acid contained in various candies (from food labels) and seek a correlation between type of acid and level of tartness/sourness. Here is a sample, very rudimentary experiment: http://www.education.com/science-fair/article/candy-ph/. Although rudimentary, it requires melting of each of the candies, perhaps a painstakingly slow process. This one dissolves the candies instead (although no chocolates were tested): http://cascience6isp.wikispaces.com/file/view/Emily%20K2013.pdf/415709538/Emily%20K2013.pdf. It also uses a pH meter, rather than pH paper, as in the first experiment.
Students can investigate this study on tooth erosion as it relates to Gatorade imbibement, and comment on the scientific rigor of the experiment, possibly suggesting ways to improve the procedure. (http://www.webdental.com/profiles/blogs/why-gatorade-erodes-teeth)
Interested students can test their own saliva before and after eating, to show changes in pH as a result of ingested food. The standard way of testing pH of saliva is the following: Wait at least two hours after eating or drinking to ensure that the food consumed does not alter test results. Cleanse the mouth by filling the mouth with saliva and then swallowing or spitting. Fill the mouth again with saliva and place a small amount on a pH strip. The strip will change colors based on the results. (http://www.livestrong.com/article/192281-what-is-ph-of-saliva/) Varying the times following eating can show changes in pH. Be sure to include a test after brushing the teeth.
If you’re not planning to do a debate on the role of water fluoridation in reducing tooth decay in your classes, students can research the pros and cons of this topic and write a report/make a class presentation. See the reference in the “In-Class Activities” section, above, for links to sites to begin their online research. Note: you may NOT want to give them this site: http://www.debate.org/debates/Water-fluoridation-is-safe/1/, as it contains an already-established debate. Alternatively, you may want to restrict the debate to one aspect of the controversy, as the debate above does, focusing on the safety of fluoride in the diet.
(non-Web-based information sources)
30 Years of ChemMatters
The references below can be found on the ChemMatters 30-year DVD (which includes all articles published during the years 1983 through April 2013 and all available Teacher’s Guides, beginning February 1990). The DVD is available from the American Chemical Society for $42 (or $135 for a site/school license) at this site: http://ww.acs.org/chemmatters. Click on the “Archive” tab in the middle of the screen just under the ChemMatters logo. On this new page click on the “Get 30 Years of ChemMatters on DVD!” tab at the right for more information and to purchase the DVD.
Selected articles and the complete set of Teacher’s Guides for all issues from the past three years are available free online at the same Web site, above. Simply access the link and click on the aforementioned “Archive” tab.
This article from 1986 provides a brief history of tooth decay prevention and discusses the role tooth paste plays in preventing tooth decay and the ingredients of present-day tooth pastes. The author also discusses demineralization and re-mineralization of tooth enamel. (Yohe, B. Tooth Paste. ChemMatters, 1986, 4 (1), pp 12–13)
OK, fluoride is used to prevent cavities, but where does fluorine come from? Here’s a brief history of the trials and tribulations of the search for and discovery/isolation of the element fluorine. (Davenport, D. The Back Burner: Going Against the Flow: The Isolation of Fluorine. ChemMatters, 1986, 4 (4), pp 13–15)
This 1988 article discusses sugar and artificial sweeteners. It shows their structures and discusses a “triangle of sweetness” (a 3-sided structure containing corners of a hydrogen bond donor site, a receptor site, and a hydrophobic site) to which all sweeteners must relate chemically and by shape. At the end of the article is a 2-page insert form that contains paper molecular models of glucose and cyclamate that can be cut out and then used to show how they relate to the triangle of sweetness. (Emsley, J. Artificial Sweeteners. ChemMatters, 1988, 6 (1), pp 4–8, plus 2-page insert)
Author Owsley relates the story of a horrific murder in which the body was burned and crushed, leaving almost no traceable evidence. But small bone and tooth fragments left behind were enough to test using forensic apparatus. In this case, amalgam fillings finally led to the solving of the case. (Owsley, D. Fragments of Murder. ChemMatters, 1996, 14 (2), pp 12–15)
In this article, author Baxter investigates mouthwashes and their effectiveness at reducing bad breath and tooth decay. (Baxter, R. Mouthwash: What’s in it for You? ChemMatters, 1996, 14 (4), pp 6–8)
Author Graham describes the mysterious deaths of 4 family members after a fire. He describes the symptoms of the family members and the investigation done by scientists to establish mercury poisoning—from the refining of contaminated metals from unused mercury-amalgam dental capsules. A sidebar explains the chemistry behind the toxicity of mercury. (Graham, T. Mystery Matters: Nightmare on White Street. ChemMatters, 1996, 14 (4), pp 9–11)
This is an early article on whitening of teeth that briefly discusses the history of tooth whitening, and the present-day use of carbamide peroxide as a source of hydrogen peroxide to bleach teeth. (Ruth, C. Teeth Whitening. ChemMatters, 2003, 21 (4), pp 7–9)
The December 2003 ChemMatters Teacher’s Guide accompanying the “Teeth Whitening” article above contains more on the history of whitening agents and toothpaste. It even offers a “toothbrush timeline”.
Here’s another, more recent article on artificial sweeteners. (Brownlee, C. The Skinny on Sweeteners. ChemMatters, 2011, 29 (3), pp 15–16)
The October 2011 ChemMatters Teacher’s Guide has lots more information on artificial sweeteners.
This article discusses bodily functions that result in bad smells or less-than-flattering appearance (acne, bad breath and flatulence). In his coverage of bad breath, author Rohrig discusses tooth decay as an offshoot of bad breath. He describes demineralization and remineralization and the role of fluoride in tooth decay. (Rohrig, B. Demystifying Gross Stuff. ChemMatters, 2011, 29 (3), pp 12–14)
The October 2011 ChemMatters Teacher’s Guide has lots more information about tooth decay and fluoride water treatment to combat decay.
The topic of tooth whitening is discussed in this article. It includes the safety of whitening methods used today. (Sitzman, B.; Goode, R. Open for Discussion: Teeth Whiteners. ChemMatters, 2013, 31 (1), p 5)
Web Sites for Additional Information
(Web-based information sources)
More sites on the structure of the tooth
A good black-and-white diagram of a tooth’s structure can be found at http://www1.us.elsevierhealth.com/SIMON/Bird/modern/EIC/graphics/7627_04_24.jpg.
This 2007 paper, “An Overview of the Dental Pulp: Its Function and Responses to Injury,” describes the role of dental pulp in maintaining healthy teeth: http://www.ada.org.au/app_cmslib/media/lib/0704/m70470_v1_633112728503963750.pdf.
This paper, “The Role of Dentin in Tooth Fracture”, reports on studies using scanning electron microscopes (SEM) that show that the softer-than-enamel dentin absorbs some of the stresses of mastication on the enamel, thus preventing propagation of microfractures through the enamel, which would result in cracking the enamel: https://str.llnl.gov/str/JanFeb08/pdfs/01.08.3.pdf.
More sites on the chemical structure of tooth enamel
A May 2006 article in the Journal of Chemical Education, “Calcium Phosphates and Human Beings” by Sergey V. Dorozhkin discusses at length the naturally-occurring crystalline varieties of apatite (calcium phosphate) in rocks and minerals, and its role in mammals, especially humans, in their bones and teeth. (Dorozhkin, S. Calcium Phosphates and Human Beings. J. Chem. Educ., 2006, 83 (5), p 713) The abstract of the article is available online at http://pubs.acs.org/doi/abs/10.1021/ed083p713; the pdf of the article is available only to subscribers of J Chem. Educ. at this same URL.
A series of 32 slides from Prof. Colin Robinson of the Leeds Dental Institute, UK, provides information on tooth enamel. His slides aim
To recognise the structure of calcium hydroxyapatite, the main mineral component of the dental tissues
To understand apatite structure in terms of foreign ion substitutions and their effect in relation to enamel behaviour
To recognise the variations in chemical composition of dental enamel in relation to disease and eventually development
The slides illustrate the chemical content and structural arrangement of hydroxyapatite, and the varying chemical content of tooth enamel in various locations on the tooth. (http://www.academia.edu/1732481/Dental_Enamel_Chemistry)
This page from webmineral.com provides the unit-cell structure of apatite. This page requires Java to work, and you probably will need to add this site to your “exceptions list” in Java, otherwise security prevents you from viewing it. The Java structure is rotatable, it can be animated to rotate, and you can change the appearance to include/exclude atoms, bonds, polyhedral structures, labels, etc. (http://webmineral.com/jpowd/JPX/jpowd.php?target_file=Apatite-%28CaOH%29.jpx#.Ve3uWM-FNOQ)
More sites on tooth decay
Simplyteeth.com provides a wealth of basic information about teeth, from anatomy to decay causes, prevention, and treatment: http://simplyteeth.com/.
This site discusses the dental erosion experienced by a man who drank 1.5 liters of cola per day for several years. It offers a detailed medical description of his case. It also includes photos of his teeth. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2676420/)
This PubMed site provides a very detailed 2010 report discussing tests done with colas to show their effects on teeth and the environment of the mouth: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2997506/?tool=pubmed.
This webmd.com site discusses the various causes of dental erosion: extrinsic, intrinsic and environmental: http://www.webmd.com/oral-health/guide/tooth-enamel-erosion-restoration.
This site provides a brief table of Kas and pKas of various common acids (with names and formulas), including carbonic, phosphoric and citric acids: http://2012books.lardbucket.org/books/principles-of-general-chemistry-v1.0/s31-appendix-c-dissociation-consta.html.
Here’s a site that covers rather extensively “Acidity, Basicity, and pKa”. This might be most useful as a teacher introduction/review of the topics, although portions (or maybe all for a better student) could be used by students. http://www.columbia.edu/~crg2133/Files/CambridgeIA/Chemistry/AcidityBasicitykPa.pdf
Here is a set of 9 sessions from the Khan Academy on acid-base equilibria: https://www.khanacademy.org/science/chemistry/acids-and-bases-topic/copy-of-acid-base-equilibria.
The American Chemical Society publication Chemical and Engineering News (C&EN) frequently publishes “What’s That Stuff?”, one-page articles on specific useful items. This article focuses on fluoride toothpaste and fluoridated water, and the sources for the fluoride in both: http://pubs.acs.org/cen/whatstuff/stuff/7916sci4.html, available to all.
You can access a rather detailed description of how enamel forms and how it demineralizes, as well as photomicrographs of tooth enamel, with and without fluoride, at http://www.dimensionsofdentalhygiene.com/ddhright.aspx?id=5620.
This site discusses what causes tooth decay, and how to prevent it. Its focus is on the role played by foods we eat. (http://www.human-health-and-animal-ethics.com/health/dental-care/tooth-decay.php#How%20to%20prevent%20tooth%20decay)
This site from Virtual Chembook describes the process of food, saliva and S. mutans mixing in the mouth, most likely resulting in dental cavities: http://chemistry.elmhurst.edu/vchembook/548toothdecay.html.
Dentist Brian Palmer’s site contains 3 pdf documents (among others) that discuss abfraction of teeth. Apparently, some dentists believe this theory and some do not. (http://www.brianpalmerdds.com/hypothesis_abfractions.htm)
More sites on food’s effects on tooth decay
This site from the Mayo Clinic discusses artificial sweeteners and sugar substitutes: http://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/artificial-sweeteners/art-20046936.
This 2003 paper from the American Journal of Clinical Nutrition reports on research done on the relationship between food intake and dental caries worldwide. (Touger-Decker, R. and van Loveren, C. Sugar and Dental Caries. Am J Clin Nutr, 2003, 78 (suppl), 881S–92S; http://ajcn.nutrition.org/content/78/4/881S.full.pdf+html)
More sites on effects of brushing and flossing
Here’s a site from “Save Your Smile”. Everything You Wanted to Know about Toothpaste: http://www.saveyoursmile.com/toothpaste/toothpaste-a.html.
This 1978 article from J. Chem. Educ., Chem I Supplement: Chemistry in Oral Health describes the four main ingredients in oral dentifrices. (Chemistry in Oral Health. J. Chem. Educ., 1978, 55 (11), p 736; abstract only, http://pubs.acs.org/doi/abs/10.1021/ed055p736. The article is available at this same URL only to subscribers.)
More sites on fluorine and fluoride treatment of teeth
This page from the Journal of Chemical Education discusses fluorine’s history of discovery and uses: Banks, A. What’s the Use? Fluorine. J. Chem. Educ. 1990, 67 (5), p 373; abstract here: http://pubs.acs.org/doi/abs/10.1021/ed055p736; article available to subscribers at this same URL.
Another article from J. Chem. Educ. Discusses fluoride: its history, natural source, various compounds used in dental materials, and chemistry in preventing caries. (Rakita, P. Chemistry for Everyone: Dentifrice Fluoride. J. Chem. Educ., 2004, 81 (5), pp 677–679; abstract online at http://pubs.acs.org/doi/abs/10.1021/ed081p677; article for subscribers at same URL.
An article in the 1963 Proceedings of the Nutrition Society titled, “Theories on the Mode of Action of Fluoride in Reducing Dental Decay,” presents an in-depth treatment of the role of fluoride in prevention of tooth decay, at http://journals.cambridge.org/action/displayFulltext?type=1&fid=784036&jid=PNS&volumeId=22&issueId=01&aid=784028.
The 1963 paper “Theories on the Mode of Action by Fluoride in Reducing Dental Decay” from the Proceedings of the Nutrition Society discusses then-recent research into the ways that fluoride aids in cavity-reduction: http://journals.cambridge.org/download.php?file=%2FPNS%2FPNS22_01%2FS0029665163000227a.pdf&code=6b757e835089bfe0cc1b3917051f9ad5.
Here is a 2006 very brief, 2-page flyer from the Centers for Disease Control (CDC) on the benefits of water fluoridation: http://www.cdc.gov/fluoridation/pdf/natures_way.pdf.
And a 69-page 2005 document, “Fluoridation Facts”, from the American Dental Association (ADA) provides detailed answers and facts to substantiate their answers to more than 50 commonly-asked questions about water fluoridation. The document also contains more than 350 references (vast majority of references are not linked to World Wide Web). (http://www.ada.org/~/media/ADA/Member%20Center/FIles/fluoridation_facts.ashx)
This is a 2013 video clip (9:09) from an Australian (Queensland [Qld]) ABC television news show that discusses the pros and cons of water fluoridation: http://www.abc.net.au/catalyst/stories/3821248.htm. Viewing this might be a good way to begin a research study/debate on the controversy, as it presents some of both sides of the issue.
This site from the Fluoride Action Network provides 50 reasons NOT to fluoridate drinking water: http://fluoridealert.org/articles/50-reasons/.
And from the same organization comes the document “The Case Against Fluoride”, with 40 ways to rebut claims from pro-fluoridation groups: http://www.fluoridealert.org/wp-content/uploads/proponent_claims.pdf
From the National Academy of Sciences (NAP), you can download a pdf copy of the 507-page 2006 National Research Council’s document “Fluoride in Drinking Water: A Scientific Review of EPA’s Standards” at http://www.nap.edu/openbook.php?record_id=11571. The document is replete with detailed information on all known aspects of fluoride effects on health, and only a small portion is concerned with fluoride in teeth. You can download chapter by chapter or the entire document. You can register with NAP, or you can download a copy as a guest. NAP has many very useful documents available for purchase or for free download, so it might be useful to register.
More sites on saliva and equilibrium in the mouth
This site from the European Food Information Council (EUFIC), “Saliva—more than just water in your mouth”, provides much information on the role of saliva in preventing tooth erosion. It includes material on inorganic erosion (providing calcium and phosphate ions), as its effects on bacteria (preventing bacterial build-up on enamel via its slipperiness, attracting bacteria to it instead of to enamel, thus subsequently being swallowed, and actually killing bacteria via lysozyme). (http://www.eufic.org/article/en/artid/Saliva-more-than-just-water-in-your-mouth/)
More sites on treating tooth decay—mercury amalgam fillings
The National Capital Poison Center has an extensive, well-documented Web page describing fillings in general and amalgam fillings in particular, especially relative to their safety. (http://www.poison.org/current/dentalamalgamsandmercury.htm)
This 116-page pdf document comprises the complete FDA 2008 final ruling on “Dental Devices: Classification of Dental Amalgam, Reclassification of Dental Mercury, Designation of Special Controls for Dental Amalgam, Mercury, and Amalgam Alloy. It includes more than 80 references the FDA used in its study/decision to change dental amalgams from Class I to Class II devices. (http://www.fda.gov/downloads/MedicalDevices/ProductsandMedicalProcedures/DentalProducts/DentalAmalgam/UCM174024.pdf)
This site from the European Commission, Health & Consumer Protection, Consulate-General’s Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR), presents information on amalgam fillings, and alternative materials used for fillings, through a simple series of Q & As. The document is distributed via GreenFacts.org. (http://ec.europa.eu/health/opinions/dental-amalgam-l1_en.pdf)
This 74-page 2008 document from the European Commission, Health & Consumer Protection, Consulate-General’s Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) provides detailed information on their research and findings regarding the safety of mercury amalgams. This is the complete document from which the preceding source was taken and reformatted. (http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_016.pdf)
Here is a 4:26 video clip close-up of a cavity and its repair via an amalgam restoration: https://www.youtube.com/watch?v=ehFUq2t5O-U&feature=player_embedded
The online source “Dental Amalgam: A Scientific Review and Recommended Public Health Service Strategy for Research, Education and Regulation” is an extensive report published in 1993 of research done and compiled by the Subcommittee on Risk Management of the Committee to Coordinate Environmental Health and Related Programs, of the Public Health Service. http://web.health.gov/environment/amalgam1/ct.htm.
This 6-page pdf document discusses the history, production and use of mercury amalgam in tooth fillings: http://prospect.rsc.org/metalsandlife/9.16b.pdf.
This site on the FDA Web site provides a passionate plea by doctors, dentists, and researchers, backed up by much evidence, asking the FDA to ban mercury in the United States: http://www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials/medicaldevices/medicaldevicesadvisorycommittee/dentalproductspanel/ucm236379.pdf.
The article “Toxic Teeth: Are Amalgam Fillings Safe?” from the Dr. Oz television show, discusses amalgam fillings: http://www.doctoroz.com/article/toxic-teeth-are-our-amalgam-fillings-safe.
More sites on treating tooth decay—composite fillings
Webmd.com provides a 7-page Web site detailing the work dentists do on fillings. Page 2 in particular lists advantages and disadvantages of each type of tooth filling: cast gold, mercury amalgam, and composite: http://www.webmd.com/oral-health/guide/dental-health-fillings.
The bisphenol-A.org Web site provides much information about bisphenol-A (BPA) in general, and this page specifically deals with the topic of BPA leaching from composite fillings and dental sealants: http://bisphenol-a.org/human/dental.html. Going to their “Myths about BPA” page (http://bisphenol-a.org/about/bpa-myths/index.html) gives the discerning reader a better understanding on their position concerning the health effects of BPA.