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BDS3 Op Tech > tooth whitening > Flashcards

tooth whitening Flashcards

1
Q

2 types of causes of tooth discolouration

A

extrinsic and intrinsic

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2
Q

5 extrinsic sources of tooth staining

A
  • smoking (commonest)
  • tannins
    • tea
    • coffee
    • red wine
    • guiness
  • chromogenic bacteria (younger)
  • chlorohexidine
  • iron supplements
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3
Q

9 intrinsic causes of tooth discolouration

A
  • Fluorosis
  • Tetracycline rarer now, can be acne teens, bands
  • 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)
  • Hyperbilirubinaemia (green teeth) rare
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4
Q

cause of this tooth discolouration

A

pipe smoking

higher tar contant so greater discolouration than regular cigarettes

EX

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5
Q

cause of this tooth discolouration

A

black stain by chromogenic bacteria

EXO

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6
Q

cause of this tooth discolouration

A

tetracycline staining

see in bands - relates to formation of tooth and time tetracylcine given

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7
Q

cause of this tooth discolouration

A

porphyria

red primary teeth

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8
Q

cause of this tooth discolouration

A

fluorsis

quite common in some regions

INT

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9
Q

first method for tooth whitening

A

non and minmally invasive methods of treatment

hygiene phase therapy - scaling

can be all that is needed

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10
Q

2 types of tooth bleaching

A

external vital bleacing

internal non-vital bleaching

can be used together in non-vital teeth

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11
Q

simplest tooth bleaching method

A

external vital bleaching

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12
Q

how does external vital bleaching work

A

Discolouration 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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13
Q

active agent in bleaching

A

hydrogen peroxide H2O2

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14
Q

H2O2 in external vital bleaching

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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15
Q

active oxidising agent in H2O2

A

Free radical per hydroxyl (HO2)is formed.

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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16
Q

3 uses of free radical hydroxyl (HO2) formed from H2O2

A
  • 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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17
Q

H2O2 in water

A

acidic solution formed

breaks down to form water and oxygen

free radical hydroxyl (HO2) is formed

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18
Q

10 constituents of bleaching gel

A
  • Carbamide peroxide
  • Carbopol
  • Urea
  • Surfactant
  • Pigment dispersers
  • Preservative
  • Flavour
  • Potassium Nitrate
  • Calcium Phosphate
  • Fluoride
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19
Q

active ingredient in vital external bleaching

A

carbamide peroxide

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20
Q

how is carbamide peroxide the active ingredient in external vital bleaching

A

breaks down to produce hygrogen peroxide and urea

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21
Q

10% carbamide peroxide ->

A

3.6% H2O2 + 6.4% Urea

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22
Q

role of urea as a breakdown substance of carbamide peroxide

A

Urea increases pH – counteracts acidification of solution by H2O2

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23
Q

carbopol role in vital external bleaching

A

Thickening agent – prevent sliding off

Slows the release of oxygen

Increases the viscosity of the gel so stays where you put it

  • Stays on teeth
    • Keeps bleaching agent on tooth for longer
  • Stays in tray

Slows diffusion into enamel

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24
Q

urea role in external vital bleaching

A

raises pH

stabilises hydrogen peroxide

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25
Q

surfactant in external vital bleaching

A

allows gel to wet the tooth surface

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26
Q

potassium nitrate and calcium phophate

in external vital bleaching

A

tooth desensitising agents

sensitivity problem in tooth whitening

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27
Q

fluroide role in external vital bleaching

A

prevents eroision

densensitising effect

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28
Q

4 factors affecting bleaching

A

time

cleanliness of tooth surface

concentration of solution

temperature

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29
Q

time effect on bleaching

A

more time -> more effect

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30
Q

cleanliness of tooth surface effect on bleaching

A

cleaner -> better

nothing in between tooth and bleach

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31
Q

temperature effect on bleaching

A

higher -> quicker effect

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32
Q

concentration of solution effect on bleaching

A

higher concentration -> more and quicker effect

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33
Q

what to do before start any tooth whitening procedure

A

Before you start always check patient is dentally fit.

  • Any leakage around carious cavity margins will lead to pulpal damage
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34
Q

once pt deemed dentally fit for tooth whitening

what is the intial stage of the procedure

A

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

  • Prevents future disagreement
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35
Q

why take shade before commencing any treatment

A
  • Dehydration of tooth from rubber dam emphasise change*
  • tooth no longer natural colour*
  • Remember to select shade before doing any work
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36
Q

6 warnings for pt about external vital bleaching

A
  • Sensitivity
  • Relapse
  • Restoration colour
  • Allergy
  • Might not work
  • Compliance with regime
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37
Q

what to say about sensitivity post external vital bleaching

A

won’t last forever

worse intially

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38
Q

restoration colour and external vital bleaching

A

doesn’t change like organic tooth

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39
Q

2 types of external vital bleaching

A

chair side/in office

home

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40
Q

3 advantages of in office external vital bleaching

A

controlled by dentist

can use heat/light - help speed up process

quick results for pt

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41
Q

4 disadvatages of in office external vital bleaching

A

time for dentist - 1hr of dentist not really doing much

can be uncomforatble - dam, open for long

results tend to wear off quicker - dehydration of tooth in procedure emphasises change

expensive

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42
Q

in office external vital bleaching procedure

A
  • Thorough cleaning of teeth
  • Ideally rubber dam
    • At least gingival mask – light cure guard
  • Apply bleaching gel to tooth
  • Apply heat/light
  • Wash/dry/repeat
  • Takes 30mins to an Hour
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43
Q

heat/light/laser in external vital bleaching

A
  • Often used with In-office bleaching
  • Mainly a marketing technique
    • No evidence of better bleaching with these additional procedures
  • Light and Laser are really just heat sources
  • Often a good initial result
    • Mainly due to dehydration
    • Wears off quickly
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44
Q

what is essential in external vital bleaching

A

protection of gingiva

esp as everything is very dry

  • Historically higher concentrations of bleaching gel were used 35% H2O2
    • ​now 6% max
  • Even with weaker solutions care is necessary
45
Q

home vital bleaching uses

A

commonest

10%-15% Carbamide Peroxide Gel

  • 16.7% Carbamide Peroxide equates to 6% hydrogen peroxide which is the maximum strength of solution. 15% tends to be the highest accessible
    • Anything stronger than this is illegal
  • Patient uses solution at home
  • Custom made tray
  • Bleaches slowly, over several weeks
  • Easy for dentist and patient
46
Q

16.7% carbamide peroxide =

A

6% hydrogen peroxide which is the maximum strength of solution.

15% tends to be the highest accessible (10-15% in home vital bleaching kits)

47
Q

commonest bleaching technique

A

home vital bleaching

48
Q

home vital bleaching requires what to be made

A

custom made set of mouth guards are required

  • Alginate impressions of teeth
    • 0.5mm thick soft, acrylic, vacuum formed soft splint made

Should stop short of gingival margin (1mm)

  • Don’t want bleaching solution to be in contact

Buccal spacer to allow for placement of gel

49
Q

important design of home bleaching guard

A

should stop short of gingival margin (1mm)

Don’t want bleaching solution to be in contact

50
Q

type of custom made mouth guard for home vital bleaching

A

0.5mm thick soft, acrylic, vacuum formed soft splint made

from alginate impressions

51
Q

3 stages of home vital bleaching procedure

A

make custom vacuum formed splint

surgery app

home care

52
Q

steps in surgery before home vital bleaching

A
  • Full mouth cleaning/polishing of teeth in surgery
  • Fit trays and check extension/comfort
  • Instruction in use
    • Clear written instructions given
  • Review at 1 week
53
Q

home steps for home vital external bleaching

A
  • Brush and floss teeth
  • Load tray
    • 1mm2 dot buccally on each tooth – only a small amount
      • No advantage to having excess, no harm to swallow
  • Fit tray in mouth
  • Requires to be in place for at least 2 hrs
  • Preferably overnight
54
Q

how much gel should be placed in home vital bleaching splint

A

1mm2 dot buccally on each tooth – only a small amount

No advantage to having excess, no harm to swallow

55
Q

results of home vital bleaching kits

A

Results are variable

  • Most patient see a result within 2 – 3 days
  • Normally reached maximum by 3 – 4 weeks

If no change in 2 weeks it is not going to work

56
Q

when to bleach?

4 factors

A
  • age related darkening/discolouration
  • mild fluorisis light brown stains
  • stopped smoking
  • tetracyclin staining
57
Q

age impact on bleaching decision

A

more exposure to extrinsic stains

Teeth with yellow/orange discolouration respond better than those with bluish/grey discolouration

58
Q

when to bleach smokers

A

don’t bleach active smokers - waste of time

only bleach smokers when successfully stopped

59
Q

when to bleach tetracyclin stains

A

debatable - pt choice ultimately

  • Prolonged treatment
  • Better with yellow and brown than grey
  • Can take months
60
Q

8 problems with bleaching

A
  • Sensitivity
  • Wears off
  • Cytotoxicity/Mutagenicity
  • Gingival irritation
  • Tooth damage
  • Damage to restorations
  • Problems with bonding to tooth
  • pt expectations need to be realistic
61
Q

sensitivity in bleaching

A
  • Common 60%+ most
  • Worse initially
  • Resolves over 2-3 days post bleaching
    *
62
Q

how can bleach induced sensitivity be managed

A

Few have to stop treatment due to it

Can do bleach day, day off, bleach day, day off

  • Needs regular to work (weeks off doesn’t work)
63
Q

5 predictors for pts being sensitive after bleaching

A
  • Pre-existing sensitivity
  • High concentration of bleaching agent
  • Frequency of change – change solution multiple times quickly
  • Bleaching method
  • Gingival recession
64
Q

issue of bleaching wearing off

A
  • Oxidised chromogens gradually reduce with time
  • Retreatment 1-3 years, varies
65
Q

cytotoxic/mutagenicity risk of bleaching

A

carcinogenic risk

  • No evidence for 10% Carbamine peroxide
  • High conc H2O2 can cause problems not in dental conc
66
Q

gingival irritation in bleaching

A

tend to be uncommon

related to conc

must check tray extension correct (1mm short of gingival margin)

67
Q

tooth damage and bleaching

A

no evidence and been in use for 15+ years

68
Q

damage to restorations from bleaching

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 - cycle

69
Q

problems with bonding and bleaching

A

Residual oxygen from the peroxide remains within the enamel structure initially

Gradually dissipates over a short time

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

Oxygen inhibited layer when bond to composite normally - REVISE

70
Q

what is chlorine dioxide

A

product used in some beauty salons and cruise liners

NEVER USE

71
Q

issue with chlorine dioxide

A

Softens and strips enamel from tooth surface

  • Chlorine dioxide has a pH of around 3 and will soften the tooth surface.

As a result of chlorine dioxide use,

  • teeth are more prone to re-staining,
  • develop a rough surface and become extremely sensitive.
72
Q

causes of internal discolouration

A

dead pulp -> bleeding into dentine

  • blood products diffuse and darken
  • grey discolouration
73
Q

indications for internal non-vital bleaching (3)

A
  • non-vital tooth
  • adeqaute RCT
  • no apical pathology
74
Q

what is internal non-vital tooth bleaching trying to do

A

dead pulp -> bleeding into dentine

  • Blood products diffuse and darken
  • Grey discolouration

Try to oxidise blood products to get back to correct tooth colour

75
Q

2 contraindications to internal non-vital tooth bleaching

A
  • Heavily restored tooth
    • Better with crown or veneer
  • staining due to amalgam
76
Q

limitation of internal non-vital tooth bleaching

A

doen’t always work but generally worth a go as non-invasive

unsure why

77
Q

3 advantages of internal non-vital tooth bleaching

A
  • Easy
  • Conservative
  • Patient satisfaction
78
Q

risk in internal non vital tooth bleaching

A

external cervical resorption - not common

due to diffusion of H2O2 through dentine into periodontal tissue

tend to be seen more in

  • high conc H2O2
  • trauma

less heat and lower conc used now = lower risk

79
Q

technique for internal non-vital tooth bleaching

A
  • Record shade
  • Prophylaxis, clean 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
      • Prevent leaching of H2O2
  • Remove any very dark dentine
  • Etch the internal surface of the tooth with 37% phosphoric acid
    • Open pores in dentine
  • Place 10% carbamide peroxide gel in cavity
  • Cotton wool over this
  • Seal with GIC

Repeat procedure at weekly intervals

80
Q

how long to repeat internal non-vital tooth bleaching

A
  • Repeat until
    • Required shade achieved
    • 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.

81
Q

how much GP to remove from pulp chamber in internal non vital tooth bleaching

A

all GP from pulp chamber and 1mm below ACJ

82
Q

why place 1mm RMGIC over GP

A

to seal canal

seals dentine and prevents root resorption and leaching of H2O2

83
Q

etch with

A

37% phosphoric acid

84
Q

reason for etching in internal non-vital bleaching

A

open pores in dentine

85
Q

temporary seal between internal non vital appoinments

A

GIC

86
Q

on achieving required shade in internal non-vital tooth bleaching then

A

restore the palatal cavity

  • Place white GP or similar in pulp chamber
  • Restore with light shade of composite

But ensure easy to regain access – as not permanent

Will gradually darken again

  • Retreatment every 4 – 5 years? Variable
87
Q

combination bleaching

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 (pt in charge)
    • Tricky for patient, must wear tray whole time – wear 24 hours a day

Bit more complicated than internal non-vital bleaching– can be faff for pt; but good results

88
Q

microabrasion

A

Removes discolouration limited to the outer layers of enamel

  • Combination of erosion (acid) and abrasion (pumice)
    • Polishing off outer layers of enamel like giving pt tooth wear
89
Q

4 indications for microabrasion

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

superficial staining only

deeper stains in enamel not suited

90
Q

technique for microabrasion

A
  • Clean teeth thoroughly
  • Rubber dam (seal is very important)
    • crucial- HCl = damage gingiva
  • 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 F gel or varnish
    • Fluoride to help reharden the surface and decrease sensitivity
  • Review after one month
    • Can be hard to tell success as teeth can appear frosty due to acid used

Can be repeated – cannot be used too often as removing enamel

91
Q

issues in many repetitions of microabrasion

A
  • Too much can lead to yellowing of the tooth as the dentine begins to show through
  • Too much will lead to permanent sensitivity
92
Q

why polish teeth with F prophy paste after microabrasion

A

as softened teeth with HCl

93
Q

concentration of HCl used in microabraion and time

A

18% HCl and pumice

  • Apply to teeth
  • Gently rub with prophy cup 5 seconds/tooth
94
Q

advantages of microabrasion (3)

A
  • Quick
  • Easy
  • No long-term problems
    • Pulpal damage
    • caries
95
Q

4 disadvantages of microabrasion

A
  • Acid
  • Sensitivity
  • Only works for superficial staining
  • Works much better for brown staining than white marks
96
Q

alternative to 18% HCl for use in microabrasion

A

37% phosphoric acid rather than HCl

  • HCl removes 100microns
  • Phosphoric acid only removes 10microns (10% of HCl)

Etch first with phosphoric acid and for longer (30s) prior to using pumice.

  • Takes longer

​Not as effective but this acid is readily available to GDP

97
Q

resin infiltration used to treat tooth discolouration of

A

white stains

98
Q

resin infiltration in tooth discolouration tx

A

Don’t remove the surface layer

  • Infiltrate the white area with resin (more porous enamel)
  • Changes the refractive index of the white area
  • Masks it and makes it look like the surrounding enamel

Marketed initially as a method of treating early caries by resin infiltration

  • Used for treatment of white spot lesions
  • Hyrdophilic resin impregnation of the porous enamel surface in white area
99
Q

pro and con of resin infiltration

A

Resin infiltration appears to demonstrate an immediate masking effect

BUT

  • The durability of esthetic results requires longer term study
    • due to potential staining
    • Aging of the low viscosity resins used
  • Resin – long term benefits unclear currently*
  • Can be good as adjunct as non-invasive management*
100
Q

UK vs USA view on tooth bleaching products

A

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.

101
Q

law in regards tooth whitening UK

A

The Cosmetic Products (Safety Amendment) Regulations 2012 (implementing Directive 2011/84 EU which amends directive 76/768/EEC) came into force in October 2012

102
Q

what must be carried out prior to any tooth whitening procedures

A

pt must be deemed dentally fit

An appropriate Clinical Examination is carried out

  • Free of Dental Pathology – caries, cavities, perio, apical etc
  • Medical contraindications
    • Very rare
    • Glucose-6-Phosphate dehydrogenase deficiency
    • Acatalasemia
      • Neither group can metabolise hydrogen peroxide
103
Q

2 medcial conditions that cannot metabolise hydrogen peroxide

therefore risk in tooth bleaching

A
  • Glucose-6-Phosphate dehydrogenase deficiency
  • Acatalasemia
104
Q

max concentration of H2O2 in tooth whitening produts

A

6% for cosmetic purposes

105
Q

who cannot have products containing 0.1-6% H2O2

A

cannot be used on any person under 18 years of age

  • except where such use is intended wholly for the purpose of preventing disease.
    • E.g. mental health benefit due to discoloration central incisor
106
Q

what level of H2O2 is safe and can be sold on market

A

Products containing, 0.1% hydrogen peroxide, including mouth rinse, toothpaste and tooth whitening or bleaching products

107
Q

range of H2O2 % which should not be available to public to buy

A

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 dentist’s prescription).

  • Breach of these regulations is a criminal offence.
  • This is enforced through trading standards
108
Q

tooth whitening/bleaching products 0.1-6% H2O2

used how

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 a dentist, hygienist, therapist or clinical dental technician

Whitening products can only be sold by dental practitioners

  • The first cycle of treatment must be supervised
  • After the first cycle the product may be provided for use by the consumer

Concentrations exceeding 6% hydrogen peroxide remain prohibited, unless wholly for the purpose or prevention of disease.

It is a criminal offence to breach these guidelines

109
Q

what will happen if supply products in excess of 6% H2O2

A

Dentists supplying bleaching products if in excess of 6% 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 (after prosecuted by Trading Standards)

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

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