Tooth Whitening Flashcards
what are the 2 main types of tooth discolouration
- extrinsic
- intrinsic
what are the causes of extrinsic tooth discolouration
○ Smoking
§ The most common cause
[Lot more discolouration in a pipe smoker than cigarette]
○ Tannins
○ Chromogenic Bacteria
[Commoner in children]
○ Chlorhexidine
[When taken in excessive amounts]
○ Iron supplements
what are tannins found in
§ Tea
§ Coffee
§ Red Wine
§ Guinness
what are the causes of intrinsic tooth discolouration
○ Fluorosis
[Quite common]
○ Tetracycline
[Used to be common, still can be likely in older people but now there is a lot more antibiotics available]
○ Non-vitality (blood products)
○ Physiological (age changes)
○ Dental Materials
○ Porphyria (red primary teeth)
○ Cystic Fibrosis (grey teeth)
○ Thalassemia, Sickle Cell anaemia (blue, green or brown teeth)
○ Hyperbilirubinaemia (green teeth)
[Theoretically this is true but never seen]
how can tetracycline cause intrinsic tooth discolouration
□ This relates to the formation of the tooth and to when the tetracycline was actually given so this can still be seen in teenagers who have been given this
□ Eg a wisdom tooth might have this banded discolouration on it because it was the only tooth still forming when the antibiotic was given
□ Can also make the bone around the tooth a different colour because the bone can absorb the drug too
what dental materials can cause intrinsic tooth discolouration
▪ Amalgam
▪ Root filling materials
□ Some materials that used to be used gave a pink colour to the tooth
what should the first method of tooth whitening for extrinsic staining always be
First method of tooth whitening for extrinsic staining should always be HPT
○ Ie clean the patients teeth
○ Hygiene phase therapy, scaling can remove staining
what are the 2 types of tooth bleaching
External Vital Bleaching
Internal Non-vital Bleaching
when can the 2 types of tooth bleaching be used together
Can be used together in non-vital teeth
what is discolouration caused by
• Discolouration is caused by the formation of chemically stable, chromogenic products within the tooth substance.
[Generally what causes discolouration is colour stable, long chain organic molecules which are within the teeth ie they are either present in the teeth initially or they are absorbed into the tooth surface]
These are long chain organic molecules.
how does bleaching work on discolouration
• Bleaching oxidises these compounds.
• Oxidation leads to smaller molecules which are often not pigmented
○ Either breaks them up into smaller compounds
- Or alternatively the other thing that can cause staining is metallic oxide groups and by oxidising these this can change the ionic level that the metallic group is at and this normally goes from being coloured to colourless
- Oxidation can cause ionic exchange in metallic molecules leading to lighter colour.
what role does hydrogen peroxide play in bleaching
- hydrogen peroxide breaks down to get oxygen free radicals
- This then reacts chemically with the large organic chromogenic molecules within your teeth and breaks them down into smaller molecules which don’t impact colour to the teeth
in vital external bleaching, what is hydrogen peroxide and how does it work
Hydrogen peroxide (H2O2) is the active agent
○ 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
§ This is the important part that causes the breakdown of the molecules
○ Fast reacting oxidising agent
what are the uses of hydrogen peroxide
○ Used as bleaching agent in industry
○ Used to bleach hair
○ Used as a disinfectant
○ Seldom an ingredient in modern tooth bleaching products.
what are the constituents of bleaching gel
○ Carbamide peroxide ○ Carbopol ○ Urea ○ Surfactant ○ Pigment dispersers ○ Preservative ○ Flavour ○ Potassium Nitrate ○ Calcium Phosphate ○ Fluoride
what is carbide peroxide role in bleaching gel
- Active Ingredient
- Breaks down to produce Hydrogen Peroxide and Urea
- 10% Carbamide peroxide → 3.6% H2O2 + 6.4% Urea
• Urea increases pH
○ Counteracts the acidic nature so that you don’t end up with as an acidic material as if you were using hydrogen peroxide on its own
what is the maximum amount of hydrogen peroxide that can be prescribed in a bleaching gel
The maximum amount of hydrogen peroxide that can be prescribed is 6%
what is carbopol role in bleaching gel
• Thickening agent
○ Without this it would be a very thin liquid being painted onto the teeth so it would just run straight off again
• Slows the release of oxygen
○ Slows reaction and keeps material in the tray for longer
• Increases the viscosity of the gel → stays where you put it
○ Stays on teeth
○ Stays in tray
• Slows diffusion into enamel
what is the role of urea in bleaching gel
- Raises pH
* Stabilises Hydrogen Peroxide
what is the role of surfactant
• Allows the gel to wet the tooth surface
what are the roles of potassium nitrate and calcium phosphate
• Tooth desensitising agents
○ Sensitivity is a problem with tooth bleaching
what is the role of fluoride in bleaching gels
• Prevents erosion
○ Hydrogen peroxide is an acidic substance despite the urea in it
• Desensitising effect
what factors affect bleaching
• Time
○ More time → more effect
○ Ie more time for the chemical reaction to occur then the more bleaching will take place
• Cleanliness of the tooth surface
○ Cleaner → better
○ If there is nothing between the tooth surface and the bleach then it will work better
• Concentration of solution
○ Higher concentration → more and quicker effect
• Temperature
○ Higher → quicker effect
what must you check before starting bleaching
- Before you start always check patient is dentally fit
Any leakage of the bleach 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
○ Good to ensure you don’t end up in a dispute with them later on if they think there has been no change as you can actually prove the difference then
what do you need to warn the patient about with bleaching
• Sensitivity
• Relapse
○ Ie the treatment doesn’t last forever
• Restoration colour
○ Restorations don’t change colour the same way teeth do
- Allergy
- Might not work
- Compliance with regime
what are the 2 types of external vital bleaching
Chair-side / in-office
Home
what are the advantages of in-office bleaching
○ Controlled by dentist
○ Can use heat/light
§ This can speed up the process
○ Quick results for patient
what are the disadvantages of in-office bleaching
○ Time for dentist
§ Dentist has to stay there while it is happening
§ Takes an hour, not a lot else to do during this time
○ Can be uncomfortable
§ Have to lie with your mouth open for an hour
§ Also the technique can be uncomfortable for the patient
○ Results tend to wear off quicker
§ For restorations want to select the composite before you put the dental dam on because the teeth can dry out and change colou
§ Patient might get a really good, white effect to begin with but actually a lot of this will be caused by dehydration of the tooth
○ Expensive
§ Eg have to pay for the dentist to be there
explain the in-office bleaching technique
• Thorough cleaning of teeth
• Ideally rubber dam
• At least gingival mask
○ Need to protect the gums
- Apply bleaching gel to tooth
- Apply heat/light
- Wash/dry/repeat
- Takes 30mins to an Hour
what is a gingival mask
Essentially a light curing material (similar to composite) which is placed around the gingival margins to protect them
what is the different to using light / laser techniques rather than using heat
- 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
○ Heats up the area to speed up the reaction and also dehydrates your teeth
• Often a good initial result
○ Mainly due to dehydration
○ Wears off quickly
• Was very popular and still is to a certain extent
what is essential when carrying out in-office bleaching
Protection of gingivae is essential
Because everything is really dry you need to be careful you don’t cause damage to the gingiva
what are practices which offer in-office bleaching likely to also prescribe when carrying out teeth whitening treatment
Even practices which offer in-office bleaching are likely to also prescribe some home vital bleaching so as the dehydration wears off that these teeth are still treated
what is the concentration of carbamide peroxide gel used in home vital bleaching
10%-15% Carbamide Peroxide Gel
○ 16.7% Carbamide Peroxide equates to 6% hydrogen peroxide which is the maximum strength of solution.
[Anything stronger than this is illegal so this is the maximum amount of hydrogen peroxide that you can possibly use]
what does the dentist need to do to provide home vital bleaching for their patient
○ Full mouth cleaning/polishing of teeth in surgery
○ Fit trays and check extension/comfort
○ Instruction in use
what sort of mouth guards are provided for home vital bleaching
• A custom made set of mouth guards are required
○ Thin
- Alginate impressions of teeth
- 0.5mm thick soft, acrylic, vacuum formed soft splint made
• Should stop short of gingival margin (1mm)
○ Don’t want there to be lots of bleach in contact with the gingival margin
• Buccal spacer to allow for placement of gel
how should the patient carry out home vital bleaching at home
○ Brush and floss teeth
○ Load tray
§ 1mm2 dot buccally on each tooth
§ What is important is how much bleach they put into the tray
§ Only need a small amount
§ Do not fill the whole tray up to the top [There is no advantage to having this much bleach on your teeth at once]
○ Fit tray in mouth
§ Requires to be in place for at least 2 hrs
§ Preferably overnight
when should patients be reviewed after starting home vital bleaching
Review at 1 week
what sort of results are seen with home vital bleaching
○ 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
when should a patient bleach their teeth?
• Age related darkening/discolouration
○ Teeth with yellow/orange discolouration respond better than those with bluish/grey discolouration
§ This varies from patient to patient
• Mild fluorosis
○ Patients with some slight dark / brown stains ~ bleaching will work very well on this
• Post smoking cessation
○ Don’t bleach smokers it is a waste of time ie they will have the stain back on the teeth in no time at all
• Tetracyclin staining?
○ Prolonged treatment
○ Better with yellow and brown than grey
○ Can take months but it can work
will older or younger patients see better results with bleaching
○ Bleaching an older persons teeth will work much better than bleaching a younger persons teeth because over the years they will pick up stains from tea / coffee / red wine / Guinness / cigarettes if the smoke
§ Older patients have darker teeth so they will see more of a change
○ Problem is that 14 year olds come in with white teeth but they want their teeth whiter
§ If you do well with bleaching you can bleach the teeth back to the colour they were when they erupted
§ But if the patient is 14 years old then the teeth won’t have been there for very long so you will get barely any change
what are the problems with bleaching
- Sensitivity
- Wears off
- Cytotoxicity/Mutagenicity
- Gingival irritation
- Tooth damage
- Damage to restorations
- Problems with bonding to tooth
when does sensitivity with bleaching occur
- Worse initially
- Resolves over 2-3 days post bleaching
- Gradually wears off during the bleaching process
what are predictors of sensitivity
○ Pre-existing sensitivity
○ High concentration of Bleaching agent
○ Frequency of change
§ If they use the bleaching agent 3-4 times per day they are more likely to experience sensitivity
○ Bleaching method
§ More likely to get sensitivity from in-office bleaching than home bleaching
○ Gingival recession
why does bleaching wear off
Oxidised chromogens gradually reduce with time
The oxidised chromogenic molecules will gradually reform over time and the tooth will darken again
Effect wears off gradually, patient probably won’t even notice at first
Some patients are okay with this
They will just top themselves up for a few days every 6-8 months
how often does retreatment of bleaching need to occur
Retreatment 1-3 years, but this varies
what can cause cytotoxicity or mutagenicity
• No evidence for 10% Carbamine peroxide
• High conc H2O2 can cause problems
There is a potential at these higher concentrations that we don’t use so not an issue
- Free radicals are potentially carcinogenic but in the low concentrations we use this won’t be a problem
- No evidence that a dental patient has been caused any damage from this point of view
what can cause gingival irritation
related to concentration
how can you prevent gingival irritation
- Must check tray extension correct
* Depends on the concentration of the bleach
can tooth damage occur with bleaching
No evidence over 15+years
can bleaching cause damage to restorations
- Probably not
* Teeth bleach, composite doesn’t
what are the problems with bleaching anterior teeth which have composite restorations
○ if they have anterior composites their teeth will bleach but the composite restorations won’t
• Patients must be aware of this before treatment starts
○ Means some anterior restorations might need to be changed to then match the colour of the bleached teeth
• If you change the restorations to match the bleached teeth continued bleaching will be required or fillings will be too light in colour
= Creates this cycle
does bleaching cause problems with bonding
• Residual oxygen from the peroxide remains within the enamel structure initially
○ Can be problems bonding to teeth immediately after them being bleached as there is a lot of extra oxygen about and within the tooth surface
• Gradually dissipates over a short time
○ Delay restorative procedures for at least 24hrs post bleaching but even better to delay for a week
what is chlorine dioxide
- This is another bleaching agent
- Never used
- Product used in beauty salons and cruise liners
- Problem is that this material is so acidic that it actually strips the enamel away from the surface of the tooth
- Softens and strips enamel from the 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.
what causes a non-vital tooth to discolour
· Dead pulp ⇢ bleeding into dentine
○ Generally due to the pulp being dead
· Blood products diffuse and darken causing a grey discolouration
what are indications for internal non-vital bleaching
· Non-vital tooth
· Adequate RCT
· No apical pathology
what are contraindications for internal non-vital bleaching
· Heavily restored tooth
○ Better with crown or veneer
· Staining due to amalgam
what are the limitations of internal non-vital bleaching
Doesn’t always work but generally worth a go.
what are the advantages of internal non-vital bleaching
· Easy
· Conservative
· Patient satisfaction
what are the risks of internal non-vital bleaching
· External Cervical resorption
why does external cervical resorption occur
○ Due to diffusion of H2O2 through dentine into periodontal tissues
○ High conc H2O2 and heat
○ Trauma important
• Probably more a theoretical risk than an actual risk but it depends on what causes the tooth to discolour in the first place
○ But this tends to be the cause more in teeth that have been affected by trauma initially and when bleach is used at higher concentrations
what is the technique for internal non-vital bleaching
- Record shade
- Prophylaxis ie clean the 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
- 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
why would you place 1mm RMGIC over GP to seal the canal
○ Seals dentine and prevents root resorption
○ Seal off the area where there could potentially be leaching through of hydrogen peroxide which could cause damage
why do you etch the internal surface of the tooth with 37% phosphoric acid
Just to kind of open the pores within the dentine
how long do you repeat internal non-vital bleaching treatment for
Repeat until
○ Required shade achieved
○ No change
how long does internal non-vital treatment usually take
• Normally takes 3 – 4 visits
○ If no change after 4 visits it is not going to work
○ Then consider crown /veneer/ composite build up.
what is done once internal non-vital treatment is completed
• Once final shade obtained restore the palatal cavity
[Want to make sure it is easy to get back in again]
- Place white GP or similar in pulp chamber
- Restore with light shade of composite
- Will gradually darken again
- Retreatment every 4 – 5 years? ~ Variable
what is combination bleaching
- Inside-outside bleaching
- Remove GP, as before, cover with RMGIC
• Make bleaching tray
○ Palatal not buccal reservoir
○ So patient can apply bleach externally as well as to the inside of the tooth
• Bleach placed in access cavity and in tray
○ Need to wear the tray 24 hours a day otherwise the access cavity will fill up with food whenever the patient is eating
• Replaced frequently over about a week
• Tricky for patient, must wear tray whole time.
○ Can be difficult for the patient
○ But it does get good results
what is micro-abrasion
• Removes discolouration limited to the outer layers of enamel
• Combination of erosion (acid) and abrasion (pumice)
○ Kind of like giving the patient tooth wear
• Essentially just polishing off some of the outer layers of the enamel where there is discolouration
what are the indications for micro-abrasion treatment
• Fluorosis
○ Ie whenever any discolouration is superficial
- Post orthodontic demineralisation
- Demineralisation with staining
- Prior to veneering if dark staining is present
what technique is used for micro-abrasion treatment
- 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
- Review after one month
- Can be repeated
why is fluoride applied during micro-abrasion treatment
○ Fluoride to help reharden the surface and decrease sensitivity
what are the problems with too much micro-abrasion treatment
○ Too much can lead to yellowing of the tooth as the dentine begins to show through
§ Cannot repeat it too often as it will gradually remove surface enamel
§ Depends where the stain is
□ If it is really superficial then micro-abrasion will work really well but if the stain is within the body of the enamel it doesn’t work as well
○ Too much will lead to permanent sensitivity
§ If too much enamel has been removed
what are the advantages of micro-abrasion
- Quick
- Easy
• No long term problems
○ Provided you stick to the outer layers of enamel
what are the disadvantages of micro-abrasion
- Acid
- Sensitivity
- Only works for superficial staining
- Works much better for brown staining than white marks.
what can be used as an alternative to HCl for micro-abrasion treatment
• You can use 37% phosphoric acid rather than HCl
○ HCl removes 100microns
○ Phosphoric acid only removes 10microns ie not a strong as acid
This can be a good thing but can also be a bad thing
what are the disadvantages of using phosphoric acid over HCl
Takes longer so might just have to do it over more visits
Not as effective but this acid is readily available to GDP
what does resin infiltration do
- Don’t remove the surface layer
- Infiltrate the white area with resin [Infiltrate the porous enamel with resin]
- Changes the refractive index of the white area
• Masks it and makes it look like the surrounding enamel
○ Creates a more natural tooth colour again
- Hydrophilic resin impregnation of the porous enamel surface in white area
- Resin infiltration appears to demonstrate an immediate masking effect ie looks really good immediately after treatment
what sort of stain is resin infiltration used for
This is particularly for white stains
what can be said about the durability of the aesthetic created by resin infiltration
• The durability of aesthetic results requires longer term study
○ due to potential staining
○ Aging of the low viscosity resins used
○ Need to consider this with all resins but particularly because this is a low viscosity resin
what is good about resin infiltration treatment
Good non-invasive way to deal with tooth discolouration
are bleaching products considered a cosmetic or medical device
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.
what needs to be checked in the clinical examination before carrying out tooth whitening
○ Free of Dental Pathology
• No caries, no cavities etc
○ Medical contraindications
• Very rare
• Glucose-6-Phosphate dehydrogenase deficiency
• Acatalasemia
□ Neither group can metabolise hydrogen peroxide
• These are very rare genetic conditions
what regulations apply to bleaching treatments
The Cosmetic Products (Safety Amendment) Regulations 2012 (implementing Directive 2011/84 EU which amends directive 76/768/EEC)
what is the greatest concentration of hydrogen peroxide or associated product that can be supplied or used
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.
are there any restrictions on what age group bleaching can be carried out on
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
Paediatric department can use bleaching solutions on children under this age and for example if they are doing internal bleaching of a darkened upper central this is considered to be necessary for the mental health of the patient
what concentration of products are widely available on the market in chemists or shops
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
what concentration of products cannot be bought from a shop or chemist
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 dentist’s prescription)
Needs to be dispensed from the dentist / dental team
what happens if dentists supply bleaching products in excess of 6%
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.
Non registrants providing tooth whitening will be prosecuted by the GDC under the Dentists Act 1984 for illegal practice of dentistry
