Tooth whitening in orthodontics

orthodontics In summary

Does whitening have a role in orthodontics? A popular cosmetic procedure which 1 in 4 adults partake in, and was proposed recently at a conference as part of finishing in orthodontics. So this podcast reviews whitening as a topic and the latest evidence in combining whitening with aligners.

Reminder the podcast is an opinion piece and is the independent work of myself and the orthodontics in summary team.

24% of adults have whitening their teeth (dentalhealth.org)

How does it work:

Bleaching is the chemical changing of darker staining on teeth termed chromogens, with the active ingredient hydrogen peroxide.

Hydrogen peroxide reacts to oxidize the chromogen, which becomes a lighter colored compound.

Hydrogen Peroxide is not a stable chemical, so Carbamide peroxide is used, which roughly breaks down to 1/3 H2O2 when mixed with water.

Hydrogen Peroxide UK limit 6%, or Carbamide peroxide 16% is used, USA, greater concentrations are used with 10% hydrogen peroxide for at home whitening, and 35% hydrogen peroxide for in office bleaching.

Children

UK guidelines GDC 2014 – no bleaching until 18, unless purpose of treating or preventing disease.’

USA: The AAPD 2023 s Safe and effective for whitening discolored teeth of children and adolescents. Avoid full-arch bleaching mixed dentition and primary dentitions

Risks

Sensitivity -

about 80% of patient’s experience sensitivity

• Tooth sensitivity usually occurs at the time of treatment and can last several days

• Upper lateral incisors – greatest sensitivity

• Directly correlated with concentration

• Greater intensity if tooth was restored Bonafe 2013

Gingival irritation

• gingival irritation begins within a day of the treatment and can also last several days

Susceptibility to demineralisation

• Suggested surface demineralization occurs as the pH of the whitening agent are acidic and hydrogen ions affect the enamel crystals,

• No difference when using manufacturers protocols including 35% H202 Tompkins 2014

• However aggressive whitening: excessive use of in office whitening Shi 2012

How long does the whitening last

Duration of correction, depends on lifestyle, with smoking and coffee reducing the correction. Expected 6-12 months of stable colour change. Wiegand 2008

Aligners

• Bleaching tray is different – reservoir for bleach, 1 or 1.5mm soft ethylene-vinyl acetate (EVA), Straight cut 2mm beyond gingiva or scalloped, with 2 mm extension onto the gingiva giving a better seal and greater patient comfort. Dosage dots to limit application beyond 2mm

• Aligners

• Usually gingival bevelled, but as effective as bleaching trays, Levrini 2020 improvement of 3.5 shades on average Seleem 2021

• tooth sensitivity and gingival irritation does not disrupt of treatment 16% Carbamide peroxide Oliverio 2019, Levrini 2020

• 2 mm thick layer of gel is advised at incisal or facial central surface of the aligner

• Bleaching with attachments present, when bleaching complete attachments removed:

• hydrogen peroxide diffuses through spaces between enamel prisms

• The composite attachment was thought to affect pigment infiltration, however with enamel polishing after composite removal, color equalization occurs without discrepancies Staley 2004

• Minimal change to aligner structure Oliverio 2019

Retainers as bleaching trays?

Use of 0.8mm Zendura, no resivoir, effective bleaching with marked or extremely marked improvement in 78% of cases with 10% Carbamide peroxide, however but this changed the VFRs’ biomechanical properties, decrease in tensile strength and an increase in hardness and internal roughness, unclear what the medium and long term effects are .Jin 2024

Bond strength

• By Bleaching a tooth there is enamel bond strength reduction by 25 % Miguel 2006

• Wait 2 weeks after bleaching for aligner attachment placement.

• Bonded retainer has not been researched