Line up a whitening pen, a box of strips and a tray kit on a pharmacy shelf and the active ingredient is much the same in each: a peroxide gel. What separates them is how long that gel stays against your teeth and how much of each tooth it reaches. Once you see it that way, choosing between them becomes a question about your teeth and your habits rather than the packaging.
Contact time and coverage do most of the work
Peroxide lightens teeth by moving into the enamel and dentine and breaking down the molecules that cause staining. The result depends on the strength of the gel, how long it sits on the tooth and whether it covers the whole visible surface. In Australia, whitening products sold directly to the public are capped at lower peroxide strengths, and stronger gels can only be supplied through registered dental practitioners. Among shop products, that leaves contact and coverage as the main differences.
A tray keeps a layer of gel against every tooth it covers for the whole session. A strip presses gel against the flat front surfaces of the front teeth. A pen leaves a thin film that saliva soon dilutes. Formats that keep more gel in contact for longer would be expected to do more, although head-to-head trials are few, and strips and trays have performed similarly in some studies.
Pens are quick, but the gel does not stay long
You paint the gel on, hold your lips away from your teeth while it sets, and carry on with your day. Pens are portable and easy, but because the layer is thin and saliva dilutes it, they may make only a small visible difference when used alone, and there is little good clinical evidence on pens by themselves. They are more useful for topping up a result between longer courses, or for touching up a single tooth that has picked up stain.
Strips suit straight teeth with mild staining
Whitening strips are thin flexible films already coated with gel. There is nothing to fit, which makes them an easy way to try whitening. A 2016 systematic review in Clinical Oral Investigations (Serraglio and colleagues) found no significant difference in colour change between over-the-counter strips and home whitening with a 10% carbamide peroxide gel in trays, though the authors rated the quality of the evidence as very low.
A strip is flat, while a smile curves. Strips tend to miss the edges of teeth, the gaps between them and any tooth that sits further back than its neighbours, which is why some people notice lighter centres and darker edges after a course. Our article on whether whitening strips work looks at the different types, including peroxide-free versions.
Trays give the most even contact, especially custom ones
There are two kinds of tray. Boil-and-bite trays from a home kit are softened in hot water and moulded in your mouth; they often fit loosely, so gel can leak onto the gums and less stays on the teeth. Custom trays are made from a scan or impression of your teeth, so they sit closely, hold gel against each tooth and keep most of it off the gums. They can usually be reused for later top-ups as long as they still fit. Our guide to how custom whitening trays work explains how they are made and worn.
Trays are the better fit for crowded or overlapping teeth, for anyone wanting the most even colour, and for people who want a plan they can repeat. The trade-off is time, since a course runs over a series of sessions as instructed.
Which format fits which situation
| Format | Often suits | Main limitation |
|---|---|---|
| Pen | Topping up an existing result, a single stained tooth | Thin layer, short contact time |
| Strips | Straight front teeth with mild surface staining | Misses curved edges, gaps and teeth that sit back |
| Boil-and-bite tray | Trying trays without a dental visit | Loose fit, gel can leak onto gums |
| Custom tray from a dentist | Crowded teeth, sensitive teeth, repeatable top-ups | Needs a dental visit and more time per session |
As a typical market range, dentist take-home whitening with custom trays commonly costs $300 to $700 in Australia, while over-the-counter strips and kits cost about $20 to $150 (iSelect). Fillings, bonding, crowns and veneers do not change colour with any of these products, so if you have them on front teeth, talk to a dentist first to avoid a mismatch.
The light in a home kit adds little
Some home kits include a small LED light. Evidence on light activation mostly comes from in-office whitening: a 2018 meta-analysis in the Journal of Dentistry (Maran and colleagues) found that adding a light to in-office bleaching did not improve colour change or affect sensitivity. There is little good evidence that the lights in home kits do more.
Getting a sensible result from any of them
Most problems come from overuse. Follow the time on the instructions, do not stack products to speed things up, and take a break if your teeth become sensitive. Brush and floss before each session so the gel reaches clean enamel, and go easy on strongly coloured food and drink straight after a session.
If you have not had a check-up in the past year, have one first. Whitening over a cavity, a cracked tooth or a leaking filling can be uncomfortable, and some discolouration sits deeper in the tooth than home products can reach; our guide to the causes of yellow teeth explains why.
Common questions
Why can a dentist offer stronger gel than a pharmacy?
Higher-strength peroxide products can only be supplied through registered dental practitioners. A dentist can also check your teeth and gums first and choose a gel and routine to suit them.
Will whitening make my teeth sensitive?
Some people notice temporary sensitivity during a course. It usually settles after stopping or taking a break. Tell your dentist if it is strong or lasts.
Can I use my clear retainer as a tray?
Sometimes, though it may not hold gel as well as a tray made for whitening. Our guide to using a retainer as a whitening tray explains when it can work.
Take-home whitening at Lumi
Lumi Dental's whitening options are Lumi Home, a take-home course, and Lumi Refresh and Lumi Radiance, which combine in-chair whitening with take-home whitening. All three include take-home whitening with dentist-supplied gel from Boutique Whitening. How much lighter teeth become varies from person to person, so we do not promise a particular shade. You can read more on our teeth whitening page, and pricing is on our current deals page.
