The colour you see in the mirror straight after in-chair whitening is not quite the colour you end up with. Teeth dry out during the session and look brighter than they really are, then settle over the next few days. Knowing that in advance makes the appointment, and the week after it, much easier to judge.
The visit itself is calm and fairly quiet. Your gums are protected, a strong peroxide gel goes on the front of your teeth in a few rounds, and your shade is recorded at the start and the end. The session usually takes around an hour or a little longer, depending on how many rounds you have. Take-home trays then continue the work over the following couple of weeks.
A check of your teeth and gums comes first
Whitening gel can make untreated decay, cracks, worn areas and exposed roots sting, and it does nothing useful on plaque or tartar. So before any whitening, a dentist or OHT checks your teeth and gums, and a scale and clean is usually done beforehand if you are due. Our article on whitening before or after a scale and clean explains why the order matters.
This is also the point to look at any fillings, crowns, veneers or bonding on your front teeth. Those materials do not change colour with whitening, so they may look darker than the surrounding teeth afterwards. If you are planning new veneers or bonding, whitening normally comes first so the new work can be matched to the lighter shade.
A 3D scan of your teeth is taken so the take-home trays can be made, and at Lumi this can happen at the same visit. If your teeth already react to cold, using a desensitising toothpaste for a week or two before the appointment can help.
What happens in the chair
Your starting shade is recorded
The clinician compares your teeth against a shade guide and takes photographs in the same light each time. That gives a fair reference for later, because memory is a poor judge of tooth colour.
Lips and gums are protected
A soft retractor holds your lips and cheeks back. A protective resin is painted along the gum line and set with a blue curing light, so the gel sits on the teeth and not on the gum. Most people find this part the strangest, simply because the mouth is held open for a while.
The gel goes on in rounds
A high-strength hydrogen peroxide gel is spread over the front surfaces of the teeth, left for a set time, removed, and replaced with fresh gel. This is repeated a few times. The clinician checks how you feel between rounds. If teeth start to zing, the next round can be shortened or skipped, so tell them.
Some systems shine a light on the teeth while the gel works. Whether the light adds much on top of the gel is still debated, and our article on whether LED whitening lights help looks at the evidence.
The finish
The gel and the gum barrier are cleaned off, a desensitising agent may be applied, and the new shade is recorded and photographed.
Only dental practitioners can use in-chair strength gel
In-chair gels are much stronger than anything sold over the counter. Under Schedule 10 of the national Poisons Standard, as summarised in the Australian Dental Association's policy statement on teeth whitening, products with more than 6% hydrogen peroxide or more than 18% carbamide peroxide may only be sold, supplied and used by registered dental practitioners as part of their practice. That is why the gums are protected and the session is supervised throughout.
Lumi Refresh or Lumi Radiance
Lumi has two in-chair options, and both come with take-home whitening afterwards.
Lumi Refresh is the gentler session. It tends to suit people whose teeth are already sensitive or who found whitening uncomfortable in the past. The take-home gel and wear time are then chosen with sensitivity in mind.
Lumi Radiance is the fuller in-chair session, often chosen by people who want a visible start soon, for example a few weeks before an event. The home trays still continue and hold the change.
Neither option can promise a shade. Your starting colour, the kind of staining and how regularly you wear the trays usually matter more than which session you choose. Our comparison of Lumi Home, Refresh and Radiance sets out who each tends to suit.
Sensitivity is common and usually short-lived
The most common side effect is sensitivity: brief, sharp twinges in a few teeth, often starting a few hours after the appointment. For most people it fades within a day or two. Desensitising toothpaste, skipping very cold food and drinks for a day, and an over-the-counter pain reliever if needed are usually enough.
A small white mark on the gum can appear if a trace of gel touched it. It normally fades within a day or two. If sensitivity lasts more than a few days, or sits in one tooth only, let us know, because that can point to a crack or a leaking filling rather than ordinary whitening sensitivity. Our guide to whitening sensitivity and how to settle it has more.
Why the shade drops back a little
With your mouth held open and the gel drawing water out of the enamel, teeth become temporarily dehydrated. Dry enamel reflects light differently and looks whiter and chalkier than its true colour. Over the next day or so, saliva rehydrates the teeth and some of that extra brightness fades. Judging the colour a week or two later gives a truer picture.
This is the main reason the in-chair session is paired with trays at home. The home gel is weaker but stays on the teeth for many more hours in total, which builds the change and holds it after the teeth rehydrate. Our article on why in-chair whitening is paired with trays goes into this further.
The days and weeks after
Many dentists advise going easy on strongly coloured food and drink, such as coffee, tea, red wine, cola, curry and berries, and on smoking or vaping, for a day or two after whitening. If you do have something dark, rinsing with water afterwards helps. Our list of what to eat and drink after whitening has the detail.
The take-home phase usually starts within a day or two and runs for around two weeks, followed by a colour check against your starting photos. You keep the trays, so an occasional few nights of gel can help maintain the result. How long whitening lasts varies a lot with diet, smoking and top-ups. If you have an event coming up, starting three to four weeks ahead leaves time for the home phase and for the colour to settle.
What patients ask about in-chair whitening
Is in-chair whitening stronger than take-home whitening?
It is faster to start, but not clearly more effective in the end. A 2016 systematic review by de Geus and colleagues in Operative Dentistry found no difference in whitening effect or sensitivity between at-home and in-office bleaching. An updated review by the same group in 2025 found at-home bleaching caused less intense sensitivity and a greater colour change on one of two colour measures, though the authors rated the quality of the evidence as low.
Will every stain lift?
Yellow and brown staining usually responds well. Grey staining, and staining from certain antibiotics taken in childhood, tends to respond more slowly and may need longer home whitening or other options.
Can I whiten during or after braces or aligners?
Yes. Whitening can be done during aligner treatment, often towards the end, and after braces it can start once the braces are off and your teeth and gums have been checked.
To see whether in-chair whitening suits your teeth, book a check with our team at Melrose Park. The teeth whitening page explains each option, and current details for Lumi Refresh and Lumi Radiance are on the current deals page.
