 Within a month, if you are found to be eligible to take part in this study, researchers will use custom dental trays designed for you, in order to deliver the chlorhexidine gel. During your next visit to the dental clinic, researchers will place these custom dental trays and the gel in your mouth for about 5 minutes. Over the next 30 minutes, the gel will be applied one more time. The dentist will also chart your decayed, missing, and filled teeth in a dentist chart during this visit. The dentist will also check the soft tissues of your mouth. You will have an office visit the next day Day 2 to see if you had any side effects to the chlorhexidine gel. 