Sometimes I wake up in the morning and I have white marks on my front teeth. The marks will stay on for hours. I'm sure it's not plaque because I brush regularly. What is this and how can I prevent it?

This is called fluorosis. A lot of Americans get this because we are exposed to lots of fluoride in our drinking water and toothpastes. They are not harmful, so do not worry about them.

contact your dentist i had white marks from drinking and eating to much sugary crap and not brushing and flossing regurarly. the dentist told me the spots were were my teeth were decalcifying (basically rotting, in a way) so just check cuz u dont want ur teeth to decalsify (sp?)

ITS NOOOT PLAQUE STUPIDS! it says on the question!

Try flossing every day. It gets to be a habit in a couple weeks, and your teeth feel so much cleaner that after you make a habit of it you won't want to do without. Also, plaque hides bacteria from your toothbrush, toothpaste, and even Listerine, and lets them do their dirty work on your teeth--so floss, already!

its most likely to be plaque . Dental plaque is a biofilm (usually of a pale yellow to white color) that builds up on the teeth. If not removed regularly, it can lead to dental cavities (caries) or periodontal problems (such as gingivitis). The microorganisms that form the biofilm are almost entirely bacteria (mainly streptococcus and anaerobes), with the composition varying by location in the mouth. The microorganisms present in dental plaque are all naturally present in the oral cavity, and are normally harmless. However failure to remove plaque, by regular toothbrushing means that they are allowed to build up in a thick layer. Those microorganisms nearest the toothsurface convert to anaerobic respiration, it is in this state that they start to produce acids which consequently lead to demineralisation of the adjacent tooth surface, and dental caries. Saliva is also unable to penetrate the build up of plaque and thus cannot act to neutralize the acid produced by the bacteria and remineralize the tooth surface. Plaque build ups can also become mineralised and form calculus. Frequency of brushing and good technique is important, because the nature (ie composition) of the microorganisms change as the plaque gets "older." Therefore, plaque which is 12 hours old for example is much less damaging than plaque which has not been removed in days.