Spas and salons get a bad press because they are easy targets as they aren't dentists, i suggest you go and have your teeth whitened at your local dentist, if they come out white, great, not everyone’s teeth will whiten, but you will experience the same discomfort as if you had them done at a beauty spa, apart from the fact that the dentist should guarantee that you don't get burned (white)gums with the bleaching gel by covering any soft tissue with a resin that is cured with the uv light (this is where some beauty spas/salons get it wrong, they allow bleach to seep under the resin barrier.
The preparation has to be good but you will get some zinger/shooting pains, anyone who doesn’t is lucky, once gel is applied to the enamel it opens up the pores/channels directly to the nerves duh! the level of pain varies from very little to a lot, it varies from one individual to another, but if you get zinger/shooting pains at your dentist after tooth whitening, you're not going to complain on a forum like this, you will just moan to friends or not at all, right!
Ask your dentist how many tooth whitening treatments they have performed in the last year, you just assume they know how to do it correctly, most only do a handful of treatments a year, some don't do any, and are therefore not any better than beauty spas/salons, in fact i'd argue that some beauty spa/salons are better than dentists at teeth whitening based on the fact that if those individual technicians are doing treatments every day, by their very nature they become very good at that particular task (tooth whitening).
Dentists of which i am one, have a strong lobby in the UK and an MP in parliament trying to get the EU law changed so that tooth whitening can only be performed by dentists, it is currently legal for non dentists to perform tooth whitening, but even dentists should only perform tooth whitening if they use gel that is under a certain strength of hydrogen peroxide concentration, but it’s a brave trading standards that takes a dentist to court on that, they won’t, the dentist lobby is too strong.
There are many scare stories in the press (daily mail/sun etc)all to this end, dentist are mainly trying to protect their incomes by lobbying for this, it just takes the occasional bad publicity that comes from shady operators like style smile to reflect on all other beauty spas/salons. I believe in fair comment that's
why i'm giving my opinion. The best recommendation is one from a friend or family member, be it for using a beauty spa/salon or dentist, not all are the same, look at breast augmentation as an example, i presume you would ask a cosmetic surgeon how many procedures he’d undertaken wouldn’t you?
Stop being a wuss, ask, ask, ask, an experienced practitioner would love to tell you how many treatments they’ve performed (you won’t be able to get them to shut up), insist on the most experienced practitioner. Please be open minded, there are strong lobbys at work trying to discredit spas/salons, so take note of reviews on websites like these, but also factor in what i have said.
A lot of dentists haven't a clue about tooth whitening because they have little practical experience but no one questions them. Think who would you prefer to change your car tyres, quick fit or a car dealer. I’m sure my colleagues will hate me for airing these views, but it’s still a free country, so please don’t shoot the messenger, there are bad salon/spas and bad dentists too. good luck.