You get individual attention, and the dentist can ensure that your teeth are suitable for whitening treatment in the first place. If you suffer from gum recession, for example, you might not be aware that you are liable to experience some sensitivity of the teeth following whitening treatment, especially if using a carbamide peroxide type of whitening treatment.
You may have fillings or other restorations in your front teeth that youre not aware of and these will not whiten like natural tooth substance. Your dentist can spot these and show you how to overcome this problem by whitening your teeth and then redoing the restorations to match.
Your dentist can monitor your progress and make sure your teeth whitening is carried out in a safe way, and be ready to advise in case of any problems.
Your dentist can either do whitening of your teeth in the chair using a concentrated gel plus light activation, or can have made special custom mouth trays that you can use with a slightly less concentrated gel at home. Either way you may achieve a faster result, although the use of peroxide gels is not without potential problems such as teeth sensitivity as previously mentioned.
Your dentist is a professional like a doctor or lawyer and is entitled to charge fees that reflect the years of training that led to qualification.
Your dentist is also a businessman offering a service and has overheads to pay before being able to make any profit. Rents and rates are high and the dentist gets no help with premises or staff from government sources, and therefore has to charge a fee that allows him or her to make a profit.
These factors explain why going to a dentist to whiten your teeth will cost you more than doing it yourself, and with the appearance of safe home whitening kits now, like Zero Peroxide, there really is no reason why you shouldnt do it yourself and make a big saving.