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BDS3 Operative Dentistry > Tooth Whitening > Flashcards

Tooth Whitening Flashcards

1
Q

What are extrinsic causes of tooth discoloration? (5)

A
  • Smoking
  • Tannins (tea, coffee, red wine, Guinness)
  • Chromogenic Bacteria (tend to be more common in children - get black and green stain)
  • Chlorhexidine (if used excessively)
  • Iron supplements
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2
Q

What are intrinsic causes of tooth discoloration? (9)

A
  • Fluorosis
  • Tetracycline (antibiotic)
  • Non-vitality (blood products)
  • Physiological (age changes)
  • Dental materials (amalgam, root filling materials)
  • Porphyria (red primary teeth)
  • Cystic fibrosis (grey teeth)
  • Thalassemia, sickle cell anaemia (blue, green or brown teeth)
  • Hyperbilirubinemia (green teeth)
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3
Q

What should the first method of tooth whitening for extrinsic staining be?

A
  • Should always be HPT (clean the teeth and sometimes this is all you need)
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4
Q

What are the 2 different types of tooth bleaching?

A
  • External vital bleaching
  • Internal non-vital bleaching
  • Can be used together in non-vital teeth
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5
Q

How does vital external bleaching work? (5)

A
  • Discoloration is caused by the formation of chemically stable, chromogenic products within the tooth substance
  • These are long chain organic molecules
  • Bleaching oxidises these compounds
  • Oxidation leads to smaller molecules which are often not pigmented
  • Oxidation can cause ionic exchange in metallic molecules leading to lighter colour
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6
Q

What is the active agent in vital external bleaching?

A
  • Hydrogen peroxide (H2O2)
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7
Q

How does hydrogen peroxide work in external bleaching? (8)

A
  • Forms an acidic solution in water
  • Breaks down to form water and oxygen
  • Free radical per hydroxyl (HO2) is formed. This is the active oxidising agent
  • Fast reacting oxidising agent
  • Used as bleaching agent in industry, used to bleach hair, used as a disinfectant
  • Seldom an ingredient in modern tooth bleaching products
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8
Q

What are the constituents of a vital external bleaching gel? (10)

A
  • Carbamide peroxide
  • Carbopol
  • Urea
  • Surfactant
  • Pigment dispersers
  • Preservative
  • Flavour
  • Potassium Nitrate
  • Calcium Phosphate
  • Fluoride
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9
Q

What is the role of Carbamide peroxide in in vital external bleaching gel? (4)

A
  • Active ingredient
  • Breaks down to produce hydrogen peroxide and urea
  • 10% carbamide peroxide -> 3.6% H2O2 + 6.4% Urea
  • Urea increases pH (this counteracts the acidic nature so you don’t end up with as an acidic solution as you would with hydrogen peroxide on its own)
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10
Q

There is a maximum amount of hydrogen peroxide which we can prescribe. What is it?

A

6%

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11
Q

What is the role of Carbopol in vital external bleaching gel? (4)

A
  • Thickening agent
  • Slows down the release of oxygen so slows down the reaction
  • Increases the viscosity of the gel -> stays where you put it (stays on teeth and stays in tray)
  • Slows diffusion into enamel
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12
Q

What is the role of Urea in vital external bleaching gel? (2)

A
  • Raises the pH

- Stabilises Hydrogen Peroxide (so slows down the reaction)

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13
Q

What is the role of Surfactant in vital external bleaching gel?

A
  • Allows the gel to wet the tooth surface
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14
Q

What is the role of Potassium Nitrate and Calcium Phosphate in vital external bleaching gel?

A
  • Tooth desensitising agents
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15
Q

What is the role of fluoride in vital external bleaching gel? (2)

A
  • Prevents erosion

- Desensitising effect

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16
Q

What are the factors that can affect the success of the bleaching? (4)

A
  • Time (more time -> more effect)
  • Cleanliness of the tooth surface (cleaner -> better)
  • Concentration of solution (higher concentration -> more and quicker effect)
  • Temperature (Higher -> quicker effect)
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17
Q

What should we do with the patient prior to starting vital external bleaching with them? (2)

A
  • Before you start always check the patient is dentally fit. Any leakage around carious cavity margins will lead to pulpal damage
  • Take an initial shade, agree it with the patient and record it in their notes. Better still take a photo with a shade guide included in the picture
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18
Q

When giving external vital bleaching to a patient what do we need to warn them of prior to treatment? (6)

A
  • Sensitivity
  • Relapse
  • Restoration colour (they do not change colour the same way as teeth)
  • Allergy
  • Might not work
  • Compliance with regime
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19
Q

What are the 2 types of vital external bleaching?

A
  • Chair-side/in-office
  • Home
  • There are advantages and disadvantages to both
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20
Q

What are the advantages of in office bleaching? (3)

A
  • Controlled by dentist
  • Can use heat/light (which will speed up the process)
  • Quick results for patient
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21
Q

What are the disadvantages of in office bleaching? (4)

A
  • Time for dentist
  • Can be uncomfortable (involves some sort of gingival mask)
  • Results tend to wear off quicker (a lot of the whitening effect is caused by drying out of the tooth from the patient having their mouth open for a long period of time)
  • Expensive
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22
Q

What is the bleaching technique for in office bleaching? (7)

A
  • Thorough cleaning of teeth
  • Ideally rubber dam
  • At least gingival mask
  • Apply bleaching gel to tooth
  • Apply heat/light
  • Wash/dry/repeat
  • Takes 30mins to 1 hour
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23
Q

Why is heat/light/laser used in in office bleaching?

A
  • Mainly a marketing technique
  • No evidence of better bleaching with these additional procedures
  • Light and laser are really just heat sources which speed up the reaction
  • Often get a good initial result but this is mainly due to dehydration and wears off quickly
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24
Q

What is essential in in-office bleaching?

A
  • Protection of the gingivae is essential
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25
Q

What is the most common technique of vital bleaching?

A
  • Home bleaching
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26
Q

What % of Carbamide peroxide gel can we prescribe for home bleaching kits?

A
  • 10%-15%
  • 16.7% Carbamide peroxide equates to 6% hydrogen peroxide which is the maximum strength solution. Anything stronger that this is illegal
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27
Q

What is home vital bleaching?

A
  • Patient uses solution at home
  • Custom tray made
  • Bleaches slowly, over several weeks
  • Easy for dentist and patient
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28
Q

What is the technique for making a custom tray for home vital bleaching? (4)

A
  • A custom made set of mouth guards is required
  • Alginate impressions of teeth
  • 0.5mm thick, soft, acrylic, vacuum formed soft splint made
  • Should stop short of gingival margin (1mm)
  • Buccal spacer to allow for placement of gel
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29
Q

What needs to be done in the surgery for home vital bleaching? (3)

A
  • Full mouth cleaning/polishing of teeth in surgery
  • Fit trays and check extension/comfort
  • Instruction in use
30
Q

What needs to be done at home for home vital bleaching? (6)

A
  • Brush and floss teeth
  • Load tray (1mm^2 dot buccally on each tooth)
  • Fit tray in mouth (requires to be in place for at least 2 hours but preferably over night)
  • Clear written instructions given
  • Review at 1 week
  • Results are variable
31
Q

How are the results for home vital bleaching variable? (3)

A
  • Most patients see a result within 2-3 days
  • Normally reached maximum by 3-4 weeks
  • If no change in 2 weeks then it is not going to work
32
Q

When would we bleach teeth due to age related darkening/discoloration?

A
  • Teeth with yellow/orange discoloration respond better than those with bluish/grey discoloration
33
Q

What kind of fluorosis would we consider bleaching for?

A

Mild fluorosis

34
Q

When would we consider bleaching for a patient who is a smoker?

A
  • Post smoking cessation

- Don’t bleach a smokers teeth as it is a waste of time

35
Q

When would we bleach the teeth of someone with tetracycline staining?

A
  • Prolonged treatment
  • Better with yellow and brown than grey
  • Can take months
36
Q

What are some problems we can have with bleaching? (7)

A
  • Sensitivity
  • Wears off
  • Cytotoxicity/mutagenicity
  • Gingival irritation
  • Tooth damage
  • Damage to restorations
  • Problems with bonding to teeth
37
Q

How common is sensitivity in tooth whitening?

A
  • Common 60%+
  • Worse initially
  • Resolves over 2-3 days post bleaching
38
Q

What are predictors of sensitivity? (5)

A
  • Pre-existing sensitivity
  • High concentration of bleaching agent
  • Frequency of change
  • Bleaching method (more likely from office bleaching than home bleaching)
  • Gingival recession
39
Q

Why does bleaching wear off?

A
  • Oxidised chromogens gradually reduce with time

- Retreatment 1-3 years, varies

40
Q

When might we get cytotoxicity/mutagenicity?

A
  • No evidence for 10% Carbamine peroxide

- High conc H2O2 can cause problems

41
Q

When can gingival irritation occur?

A
  • Related to the concentration

- Must check tray extension is correct

42
Q

One possible side effect is tooth damage. IS this common?

A
  • No evidence of this on over 15 years
43
Q

Does bleaching cause damage to restorations? (4)

A
  • Probably not
  • Teeth bleach, composite doesn’t
  • Patients must be aware of this before treatment starts
  • If you change the restorations to match the bleached teeth continued bleaching will be required or fillings will be too light in colour
44
Q

Explain if tooth bleaching has problems in bonding and how we should alter or treatment?

A
  • Residual oxygen from the peroxide remains within the enamel structure initially

It gradually dissipates over a short time:

  • Delay restorative procedures for at least 24hrs post bleaching
  • Better to delay for a week
45
Q

Chlorine dioxide is another bleaching agent. Do we use it?

A
  • NEVER
  • This is something that is used in beauty salons
  • This material is so acidic (pH of about 3) that it strips the enamel from the surface of the tooth
  • As a result of chlorine dioxide use teeth are more prone to re-staining, develop a rough surface and become extremely sensitive
46
Q

What are the causes of internal tooth discoloration? (3)

A
  • Dead pulp -> bleeding into dentine
  • Blood products diffuse and darken
  • Grey discoloration
47
Q

What are the indications for internal non-vital bleaching? (3)

A
  • Non-vital tooth
  • Adequate RCT
  • No apical pathology
48
Q

What are contraindications for internal non-vital bleaching? (2)

A
  • Heavily restored tooth (better with crown or veneer)

- Staining due to amalgam

49
Q

What is the limitation with internal non-vital bleaching?

A
  • Doesn’t always work but generally worth a go
50
Q

What are the advantages of internal non-vital bleaching? (3)

A
  • Easy
  • Conservative
  • Patient satisfaction
51
Q

What are the risks of internal non-vital bleaching? (1)

A

External cervical resorption:

  • due to diffusion of H2O2 through dentine into periodontal tissues
  • High conc H2O2 and heat
  • Trauma important (this tends to occur more in teeth that have been affected by trauma - this is not something that happens commonly)
52
Q

What is the technique of internal non-vital bleaching? (17)

A
  • Record shade
  • Prophylaxis (clean tooth externally)
  • Rubber dam
  • Remove filling from access cavity
  • Remove GP from pulp chamber and 1mm below amelo-cemental junction
  • Place 1mm RMGIC over GP to seal canal (seals dentine and prevents root resorption)
  • Remove any very dark dentine
  • Etch the internal surface of the tooth with 37% phosphoric acid
  • Place 10% carbamide peroxide gel in cavity
  • Cotton wool over this
  • Seal with GIC
  • Repeat procedure at weekly intervals
  • Once final shade obtained restore the palatal cavity
  • Place white GP or similar in the pulp chamber
  • Restore with light shade of composite
  • Will gradually darken again
  • Retreatment every 4-5 years (variable)
53
Q

How often should you repeat internal non-vital bleaching? (2)

A

Repeat until

  • Required shade achieves
  • No change

Normally takes 3-4 visits. If no change after 4 visits it is not going to work and consider crown/veneer/composite build up

54
Q

What is combination bleaching? (6)

A
  • Inside-outside bleaching
  • Remove GP, as before, cover with RMGIC
  • Make bleaching tray (palatal not buccal reservoir)
  • Bleach placed in access cavity and in tray
  • Replaced frequently over about a week
  • Tricky for patient as must wear tray the whole time (difficult for patient but gets good results)
55
Q

What is micro-abrasion? (2)

A
  • Removes discoloration limited to the outer layers of enamel
  • Combination of erosion (acid) and abrasion (pumice)
56
Q

What are indications for micro-abrasion? (4)

A
  • Fluorosis
  • Post orthodontic demineralisation
  • Demineralisation with staining
  • Prior to veneering if dark staining is present
57
Q

What is the technique for micro-abrasion? (12)

A
  • Clean teeth thoroughly
  • Rubber dam (seal is very important)
  • Mix 18% HCl and pumice
  • Apply to teeth
  • Gently rub with prophy cup 5 seconds/tooth
  • Wash
  • Repeat up to 10x
  • Remove rubber dam
  • Polish teeth with fluoride prophy paste
  • Apply fluoride gel or varnish (Fluoride to help harden the surface and decrease sensitivity)
  • Review after 1 month
  • Can be repeated (too much can lead to yellowing of the tooth as the dentine begins to show through, too much will lead to permanent sensitivity)
58
Q

What are the advantages of micro-abrasion? (3)

A
  • Quick
  • Easy
  • No long term problems (pulpal damage, caries)
59
Q

What are the disadvantages of micro-abrasion? (4)

A
  • Acid
  • Sensitivity
  • Only works for superficial staining
  • Works much better for brown staining than white marks
60
Q

What can we use for micro-abrasion instead of HCl?

A
  • You can use 37% phosphoric acid
  • HCl removes 100 microns
  • Phosphoric acid only removes 10 microns
  • Etch first with phosphoric acid and for longer 30s prior to using pumice
  • It is not as effective but the acid is readily available to GDP
61
Q

What is resin infiltration? (4)

A
  • Don’t remove the surface layer
  • Infiltrate the white area with resin
  • Changes the refractive index of the white area
  • Masks it and makes it look like the surrounding enamel
62
Q

What is resin infiltration used for? (3)

A
  • Marketed initially as a method of treating early caries by resin infiltration
  • Used for treatment of white spot lesions
  • Hydrophilic resin impregnation of the porous enamel surface in white area
63
Q

Resin infiltration appears to demonstrate an immediate masking effect but…?

A
  • The durability of esthetic results requires longer term study:
  • Due to potential staining
  • Aging of the low viscosity resins used
64
Q

What Act covers teeth whitening?

A
  • The cosmetic products (safety amendment) regulations 2012 came into force in October 2012
  • In the UK tooth bleaching products are considered a cosmetic as opposed to the USA (and most of the rest of the world) where they are a medical device
65
Q

Prior to prescribing anything in relation to tooth whitening an appropriate clinical examination is carried out. What are we looking for? (2)

A
  • Free of dental pathology
  • Medical contraindications (very rare. Glucose-6-phosphate dehydrogenase deficiency + acatalasemia (neither group can metabolise hydrogen peroxide)
66
Q

What is illegal in terms of tooth whitening? (2)

A
  • IT is illegal for tooth whitening products which contain more than 6% hydrogen peroxide or for any associated products which release greater than 6% hydrogen peroxide to be supplied or administered for cosmetic purposes
  • Products containing or releasing between 0.1% and 6% hydrogen peroxide cannot be used on any person under 18 years of age except where such use is intended wholly for the purpose of preventing disease
67
Q

What is safe and on the market for use directly to the consumer?

A
  • Products containing 0.1% hydrogen peroxide, including mouth rinse, toothpaste and tooth whitening or bleaching products are safe and will continue to be available on the market
68
Q

What can be used legally but not sold directly to the consumer?

A
  • Tooth whitening products containing or releasing between 0.1%-6% hydrogen peroxide should not be made directly available to the consumer, other than through treatment by a registered dentist (or dental hygienist or dental therapist or clinical dental technicians working to a dentists prescription)
  • Breach of these regulations is a criminal offence
  • This is enforced through trading standards
69
Q

Tooth whitening or bleaching products containing between 0.1%-6% hydrogen peroxide should be used as follows…? (2)

A
  • Exposure to these products should be limited to ensure that the products are only used in terms of frequency and duration of application
  • The products should not be directly available to the consumer, only through the dentist, hygienist, therapist or clinical dental technician
70
Q

Who can whitening products be sold by?

A
  • Only dentists
  • The first cycle of the treatment must be supervised
  • After the first cycle the produce may be provided for use by the consumer
71
Q

What will happen if a dentist is found to be supplying bleaching products in excess of 6%?

A
  • They will be prosecuted by trading standards
  • ## If a dental professional is found to be using a product in excess of 6% for cosmetic purposes,, they will face fitness to practice proceedings
72
Q

What will happen if a non-dentist is found to be providing tooth whitening products?

A
  • Non-registrants providing tooth whitening will be prosecuted by the GDC under the Dentists Act 1984 for illegal practice of dentistry

BDS3 Operative Dentistry (3 decks)

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