Difference between 20% & 35% opalescence

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Opalescence manufactures a line of take-home and in-office whitening products, all of which require a prescription from your dentist. The percentage in the product line refers to the amount of potassium fluoride (PF) used to whiten teeth. You can find the 20- and 35-percent varieties in take-home kits.

These options are not available in Opalescence's prefilled disposable or in-office lines. Both the 20- and 35-percent lines also contain carbamide peroxide (CP) to aid in whitening.

Whitening Factor

The central difference between Opalescence's 20- and 35-percent lines of whitening gels is higher percentages of PF require less time to whiten teeth. According to Teeth Whitening Product Reviews, it takes 14 days to complete the whitening program at both 20- and 30-percent PF. However, at 35-percent PF, you must wear a mouth tray for one hour a day, as opposed to up to eight hours at 20-percent PF.


The higher the percentage of PF, the greater chance you will experience sensitivity in your teeth and gums. While overnight whitening is recommended for lower percentages of PF, it is not recommended for the 20- and 35-percent PF lines, as it can lead to severe and painful sensitivity in the teeth and gums. The gel used in Opalescence's take-home kit is not water-soluble and is difficult to remove from gums. Therefore, use whitening trays with spillover reservoirs when applying the solution for more than an hour.


The 20- and 35-percent PF lines require customised dental trays. Visit a dentist and ask him to properly fit these trays. If using the 35-percent PF line, which requires less than an hour of application per day, you do not need trays with reservoirs. However, if you are using the 20-percent PF line, which requires up to eight hours of application, you need dental trays with proper spillover, or "block out" reservoirs, to prevent contact with gums.


Opalescence offers three distinct flavours in its take-home whitening gels: mint, melon and regular, regardless of the PF concentration strength. These flavours may linger long after use, so be sure you can tolerate hours of mint, melon or toothpaste flavour. If the flavour is too intense, mix some toothpaste in with the solution, although this may reduce its whitening effectiveness.