The mouthpiece trays that are available for supervised whitening sessions are considered as more reliable as compared to the ones that are available over the counter. The basis for this is simple. At least with the dentist-supervised procedures, the dentist can visit the person's home and can customize the site of the mouthpiece tray. Teeth whitening products are very affordable that customers sometimes overdo the practice that more may be better. It is not. Once the teeth arrive at its most natural white, no amount of teeth whitening will make it any whiter. From thence, a once-a-month touch up is enough for maintenance. Children up to sixteen years old is not recommended to have teeth whitening, so are pregnant women and lactating mothers. Over the years, the accumulation of the debris forms layer upon layer of film that show eventually as stain. The good thing is that while the staining agents worked its way through the pores in the rods, the whitening agents also use that access to free the teeth of the stains through oxidation reaction. For most people though, the irritation lasts only while the bleaching agent is in the mouth and dissipates gradually with use or when the strength of the mix is reduced. Again not everyone suffers mouth and gum irritation. Uneven Teeth Coloration Mouth whitening and bleaches only affect the color of the teeth. Listed below are some of the top over-the-counter solutions that you can choose for your issues with regards to your teeth. Whitening strips and gels Gels are popular solutions for teeth whitening. These are clear gels that contain a good concentration of peroxide- that main ingredient that facilitates teeth whitening. Sure there could be, in some cases, mild irritation and tooth sensitivity during the initial stages but these usually are gone after a few days of treatment. What basically it does though is change the color of the teeth superficially. Not all teeth discoloration is superficial. The teeth could be stained from the inside that will show on the outside that will not go away no matter the strips, gels, whitening pastes, bleaching pens and gurgles done.