Dear Jaimejean.

I can only refer to other dentists in Norway. I bet a quick google search on dentists in mexico with reviews from other patients can be found. It is very important you check for reviews before you chose a dentist.

Veneers can only be given to people with proper oral hygiene. If you dont have perfect oral hygiene and your dentist gives you veneers - wrong treatment. They need the normal procedures like your own teeth: brushing 2 times a day, flossing inbetween, mouthwash against caries.
They can last more than 20 years. In dental school my esthetic teacher had veneers- he was pointing at them telling us " these are 20 years old"

Your discolorations sounds like something that is coming from outside of your oral cavity since professional cleaning and whitening does not help. I need some more explanation on how the discolorations looks like and what the colour is. It can be caused by:
-smoking
-vine
-cofee
-something in your drinking water
During my 1 year of work i have seen severe discolorations caused by fluor. It is called fluorosis. Fluor is good in a certain amount. Too much fluor= bad. I get many patients from refugee camps and asylum seekers, 90 % of people from Somalia and Eritrea has fluorosis. This is because of the water they used to drink from the well during their growth. Their teeth are severe discolored with white and brown spots. In Norway you get support from the government if you have Fluorosis, so these people dont have to pay for the veneers or whatever it takes to restore their colour.

#Veneers are porcelain "shell" that cover ONLY the front part of your teeth. They are "glued" to your teeth with special composite that not only attaches, but also goes inside the material of your teeth and the veneer.
Less than 1mm of your tooth structure on the front side is removed. (0.7mm)

So! 1. find the source of your discoloration before you go for veneers. 2. find a extremely good dentist who have done many veneers, most important of all who will be minimal invasive, meaning removing as less tooth as possible to fit the veneers. ( i have seen some disasters where the dentist has removed too much, the border lines goes to the back of the tooth, this way the patient can not clean it properly and patient has lost his teeth)
check your smile - Only go for veneers on the teeth that shows when you smile.

Remember - what you remove can never be replaced. Tooth structure is not even comparable to todays best composite fillings or veneers. Also check something called lumineers. It is veneers without removing your tooth structure. But it depends if you are suitable for this treatment due to discolorations can be seen through if not used proper "glue" blocking out the discolorations.

Thank you. H