If you have a tooth that needs a crown to save it from further deterioration, how long will the new crown last? That depends on a lot of things. A crown carefully fitted to your tooth should last a long time if you take good care of it and keep it free of accidents or injuries. The material from which the crown is made will make a difference. Acrylic or porcelain, for example, are less expensive than gold or the new metals but not as durable or injury-resistant. But the greatest threat to any crown, no matter what the material, are the bacteria that cause decay.

If your gums become infected or if decay is given an opportunity to work its way under the crown, your tooth can be threatened again. Good oral hygiene at home will help you get rid of decaycausing plaque. So will a diet that's low in sugar and sugar sweetened foods. But your best protection is to get regular dental checkups. Then, any minor problems can be treated before they get out of hand. Presented in the interest of promoting a better dental health environment from the office of• Frank Soltiz, DDS 13367 Broadway Alden, New York 14004 937-7812