Will the orthodontist stop you from having braces by the colour of your teeth?

Not a color issue: It is not likely that an orthodontist would have all that much concern about the color of your teeth as much as the issues of their basic health status such as periodontal disease or decay. Ortho is mostly concerned about correcting mis aligned teeth and correcting bite problems.

White Spot Lesions: Yes--there are certain "discolorations" that might cause an orthodontist to hesitate treating you. In some instances, the enamel of the teeth can be decalcified, meaning that the enamel is "too soft" and more prone to decay. Some folks have developmental defects or "mottled enamel" that are might also be a contraindication to placing braces.

Only due to defects : If the color of your teeth is from enamel or teeth defects, then the orthodontist might not be able to place braces on your teeth if they have defective or soft uncalsifed enamel.

Not usually: Overall discoloration is not an impediment to orthodontic treatment. Teeth can always be whitenened, brightened, veneered, after braces. Some developmental defects and decalcification issues require special care, but if controlled will not prevent orthodontic treatment.

Not usually: Only if there are areas of decay that must first be treated. If the enamel is not in good condition to allow bonding of the brackets, banding might be needed -- rarely occurs. Good luck.