Reaction Characteristics of a toothbleaching agent containing H2O2 and NaF: In Vitro study of crysta

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Reaction Characteristics of a tooth-bleaching
agent containing H2O2 and NaF In Vitro study of
crystal structure change in treated
hydroxyapatite and chemical states of
incorporated fluorineJ. Cosmet. Sci., 56,
121-134 (March/April 2005)Y. Tanizawa

• Meredith Baker
• Chem 421
• February 10, 2006

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Many, many whitening products.
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I know which one I would choose

• Whitening is preferable from a cosmetic point of
  view

• Superficial discoloration can result from
  smoking, coffee, red wine
• These stains can be helped polishing abrasives
  such as toothpaste

• Internal discoloration defects in tooth
  development and medications such as tetracycline
• Cannot be removed by polishing abrasives,
  therefore formulation of bleaching agents has
  been a focus of oral care researchers and product
  developers

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Hydrogen Peroxide to the Rescue!

• Carbamide peroxide was used as an
  anti-inflammatory agent in dental treatment
• Active ingredient hydrogen or carbamide peroxide
  concentration ranging from 1 to 45
• Penetrates the enamel and dentin to oxidize the
  molecules of the staining elements
• Treatment is safe, however, 50 of patients
  experience sensitivity following
  treatment..leading to lower concentrations of
  active ingredient which lengthens treatment time
• So this study examines the mechanism of hydrogen
  peroxide and sodium fluoride in combination in
  order to lessen the adverse effects of tooth
  bleaching agents

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HAP(Hydroxyapatite)Ca10(PO4)6(OH)2

• Model substance for tooth enamel makes up bone
  mineral and the matrix of teeth
• Bioactive can be incorporated into bone
  structures, supports bone ingrowth and
  osseointegration without breaking down
• Chemical nature allows for substitutions of
  hydroxyl groups typically carbonate, fluoride
  and chloride

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X-ray Powder Diffraction

• X-ray powder diffractometer
• schematic

• Reflection of x-rays from two planes of atoms in
  a solid

Sample XRD spectra
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X-ray diffraction
No change in HAP XRD pattern with the addition
of hydrogen peroxide
HAP Treatment with H2O2/NaF Appearance of CaF2
HAP Treatment with NaF No change in XRD pattern
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X-ray photoelectron spectroscopy

• Used to determine the chemical composition of a
  surface
• XPS uses x-rays to eject electrons from
  inner-shell orbitals
• Emission intensity vs electron binding energy

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XPS

• XPS scan of HAP treated with NaF
• b. XPS scan of HAP treated with H2O2/NaF

Left Ca/P molar ratio of a vs. b Right F/Ca
molar ratio of a vs. b
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X-ray Photoelectron Spectroscopy
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XPS narrow scan spectra (Ca2p) of HAP
Binding energy values shift from HAP to CaF2

• HAP treated in H2O2/NaF
• HAP treated in NaF
• untreated

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Dihydrated Dicalcium Phosphate(DCPD)

• Background Information
• Precursor phase to remineralization process
• A constituent found in dental calculus and
  precarious lesions
• Dissolution of HAP forms intermediate product
  DCPD
• Often coexists with HAP in dental hard tissue

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DCPD XRD

• Untreated DCPD
• DCPD treated in H2O2
• DCPD treated in H2O2/NaF

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Real tooth experiments
Amino Acid Composition AA comparison between
enamel stain and saliva
XPS wide scan spectra of tooth before and after
bleaching Note the disappearance of N and the
appearance of F after bleaching
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Conclusions

• Fluoride compounds formed on the surface of HAP
  following treatment with H2O2 and NaF
• DCPD transformed into FHAP following treatment
  with H2O2 and NaF
• FHAP and CaF2 enhance remineralization and
  therefore the use of sodium fluoride should
  lessen the discomfort that could arise from
  hydrogen peroxide bleaching systems

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Special Thanks To.

• Dr. Bell
• My apartment.especially Alicia Surdyk, who is
  not a science major but came anyway, and Jane
  Dimmitt who is fabulously, and very
  appropriately, using the White Light

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References

• Tanizawa, Y., Reaction Characteristics of a
  tooth-bleaching agent containing H2O2 and NaF In
  Vitro study of crystal structure change in
  treated hydroxyapatite and chemical states of
  incorporated fluorine, J. Cosmet. Sci., 56,
  121-134 (March/April 2005)
• XRD info
• Binghamton University - Stan Whittingham
• http//materials.binghamton.edu/labs/xray/xray.h
  tml
• XPS info
• University of Maryland
• http//www.chem.umd.edu/facility/xps.html
• University of Adelaide, Australia
  http//www.chemistry.adelaide.edu.au/external/soc
  -rel/content/xps.htm