will teeth whitening work on a crown?

Whitening will only cause the difference in shade between the crown and the rest of your dentition from becoming more apparent and will not enhance the look of your smile.
Unless you are considering a replacement soon, in which case have the dental bleaching performed and then have the crown changed to match the new (whiter) colour.
Regards,
Dr Sid Gautam
Dermaskin Clinics

can u clean old crowns (smoking) to bring them back up

no but you can whiten natural teeth with peroxides, best prices at http://www.crestwhitestripsnow.co.uk
You can buy any strength gel nite white 10 percent 10% is the weakest and you buy the do it yourself bleach trays from them at http://www.crestwhitestripsnow.co.uk and comes with full instructions for you to do all the whitening at home using carbamide peroxide or hydrogen peroxide which is what dentist professionals use and charge 4 times more! http://www.crestwhitestripsnow.co.uk does free shipping and they also carry a full line of crest products, toothpastes, zoom whitening , pola night and pola day products, cheapest online source you will find with the top whitening gels and best tooth whitening products made and used by the top dentist
Source(s):
http://www.crestwhitestripsnow.co.uk

Hi Little Mizz, Unfortunatley crowns do not whiten using regular teeth whitening methods. You would need to consult with a dentist and discuss your requirements and desired results. This may mean you would need replacement crowns to match your new whitened teeth. For more information see http://www.traceybell.co.uk

A big thanks to everyone who replied to my question its been a great help. My crown is at the front and it has discoloured and its drives me crazy. I think I will go back to my dentist and see what they can do to fix the discolouration.

Teeth whitening wont work on crowns and such like, they wont change in colour, if the crowns are at the rear of your mouth it wont really matter as they wont be seen so dont worry about that, if you dont have your crowns yet you could get your teeth whitened first then get your crowns, that will mean though you will have to keep your teeth as white as your crowns.

Unfortunately you will be unable to change the colour of your crown with any method of teeth whitening. However, if you have a consultation prior to booking your appointment the practitioner will be able to access the possible match once your teeth have been treated. No guarantee can be made for exact colour changes.
Goo luck. Platinum.

You can whiten your teeth, and your teeth will get whiter, But your crown will stay the same color. Bleaching does not affect any dental work. So if you have fillings,crowns or any bonding work, and you want whiter teeth, you will need to plan to replace all this dental work after completing the whitening treatments. This is one reason it's important to have your mouth evaluated by an expert cosmetic dentist before bleaching your teeth, to spot any potential problems like these :)

sadly not
it is very important before you start any whitening for a professional to check your crowns and fillings near the front as they wont change colour