Whitening of tooth Dentistry

1. Tooth Whitening: Legal and
Clinical Considerations
MJDF Study Group
28/08/18
Laura Howard

2.  Chemical process using oxidizing agents that work on
tooth surface to penetrate enamel and dentine
resulting in a change of colour
What is Vital Tooth Whitening?

3.  Tooth colour = combination of optical properties of enamel, dentine and pulp
 Important to identify aetiology for effective treatment
 Extrinsic – superficial accumulation and adherence
 Tobacco, coffee, tea, red wine, medications (CHX, iron supplements, tannin)
 Brown, black, green colouration
 Intrinsic
 Trauma to developing tooth
 loss of vitality, remnant blood pigments infiltrating dentinal tubules
 Tetracycline, fluorosis, amelogenesis and dentinogenesis imperfecta, MIH, hypoplasia
 Iatrogenic origin – amalgam, residual GP from RCT
 Discolouration from ageing process may be considered intrinsic – more secondary
dentine formation and thinning of enamel layer
 Extrinsic discolouration can be removed with prophylactic cleaning, intrinsic
staining necessitates chemical bleaching
What are the causes of tooth
discolouration?

4.  Carbamide peroxide (CH6N2O3)
 Most home bleaching kits, breaking down into a solution of hydrogen peroxide
and urea
 Active hydrogen peroxide calculated as 1/3 of concentration of Carbamide
peroxide
 Eg 10% Carbamide peroxide = 3.6% hydrogen peroxide
 Hydrogen peroxide
 Most bleaching agents contain this in some form
 Breaks down into reactive free radicals that penetrate the tooth and oxidise
the pigment molecules (resulting in smaller molecules with reduced colour
reflectance)
 Potential adverse effects with inappropriate applications, abuse or
inappropriate whitening products
 Non-hydrogen peroxide
 Sodium Perborate as active ingredient
What are the most common dental
bleaching agents?

5.  Medical
 Undergoing radiation/chemotherapy for melanoma, photosensitive drugs
 Pregnant/breastfeeding women – no supported proof of any harmful side effects
however advised to postpone
 G-6P dehydrogenase deficiency
 Age
 Under 18 years of age
 Allergy
 Previous allergy to bleaching or any ingredients
 Dental
 Quality of enamel – inappropriate if surface/thickness is compromised
 Cavities, micro-cracks, thinned enamel
 Periodontal disease
 Hypersensitivity
 Patients Habits
 Heavy smoking habit – rapid recurrence of discolouration
When is vital bleaching
contraindicated?

6.  Initial colour of teeth
 Yellow or orange intrinsic discolouration responds best
 Bluish/grey discolouration more difficult
 Patient responsiveness
 Compliance
 Oral hygiene
 Smoking habits
 Avoiding substances that can stain teeth
 Coffee, tea, cola, mustard, ketchup, red wine, soy sauce, beetroot
 Bleach concentration
 Conc and length of time in contact with tooth surface
What are the main factors for
success of vital bleaching?

7.  Enamel undergoes a reduction in micro-hardness
 Dissolution of calcium phosphate of enamel
 Calcium lost in 12 hours of bleaching = soft drink/juice for a
few minutes
 Termination of bleaching process – re-calcification occurs
 Whether or not the re-calcified enamel is of the same
quality originally deposited into the enamel matrix remains
uncertain
Is bleaching harmful to enamel?

8.  Research has shown 2 contradictory opinions
 Halogen, Plasma arc, LED, UV
 Light source may increase the hydrogen peroxide temperature,
accelerating the reaction and formation of hydroxyl and oxygen
free radicals
 Temperature rise of 10°C increase the speed of hydrogen peroxide
decomposition by 2.2 times
 Incorporated colour pigments in the bleach promote maximum
absorption of light and subsequent conversion to heat
 The use of light source is not necessary to enhance the whitening
process
Does the use of light sources
enhance the whitening process?

9.  Level of sensitivity can differ from slight to unbearable
 Carbamide demineralisation process may extend to the EDJ
 Under cold temperatures this can be transferred through open
channels to dentine
 Negative pressure on the end of the odontoblastic processes can
create pain sensation
 Management
 NSAIDs
 Desensitiser application including toothpaste ( KNO3 e.g. Sensodyne
Pronamel)– seals dentine tubule orifice, preventing movement of fluid
 Alternative bleaching product (5%CP?), decrease treatment duration, night-
on/night-off
 Discontinue treatment
Why do some patients experience
sensitivity?

10.  Weekly visit to dentist is necessary to observe any
initial bleaching results
 2-5 weeks for desired results
 Usually 8 syringes of 1.2ml for normal treatment
 For more severe discolouration, time and quantity
may require to be doubled
At Home Technique – what is the
average time of treatment?

11.  Saturation point
 When only hydrophilic colourless structures remain
 Clinically – when the patient visits two successive times with
no colour change
 Patient must understand that bleaching isn’t permanent
treatment
 Periodic re-bleaching required
 Teeth will return to pre-bleaching colour in 3-4 years
 Suggested one in-office bleaching or 3 week at home session
per year
When can we stop the bleaching
treatment and how often can it be
repeated?

12.  Residual oxygen or peroxide in the tooth structure
inhibits the set of bonding resin
 Prevents formation of resin tag into etched enamel
 Recommended that 2 weeks should be left after
completion of whitening
 Prevent poor bonding
 Obtain colour stability
Is there any delay in providing
adhesive restorations?

13.  The Cosmetic Products Enforcement Regulation 2013 (EU)
 Maximum concentration is 6% hydrogen peroxide (16% Carbamide
Peroxide)
 Products containing/releasing 0.1-6% hydrogen peroxide must only
be made available through treatment by registered dentists (can be
carried out by dental hygienist/therapist or CDT working to dentist's
prescription)
 Clinical examination required
 For each cycle of use, the treatment is first administered by dental
practitioner or under his/her supervision to ensure level of safety
 Thereafter it can be completed by the patient
 Patient must be over 18 years old
 Products containing or releasing less than 0.1% hydrogen peroxide
are safe over the counter
Are there any safety regulatory issues
concerning bleaching?

14.  References
 Frequently Asked Questions about Vital Tooth
Whitening, Emilie Mchantaf et al, Restorative and
Aesthetic Dentistry, Dental Update 2017, p56-63
 Position Statement on Tooth Whitening, GDC, July 2016
Thanks for listening! ☺