• The primary outcome variable
• is the total net caries increment
• (root and coronal surfaces combined)
• from randomization (V1) to the 13-month follow-up visit
• (V6), scored as the number of changes recorded from V1 to V6,
• including reversals.

Adult tooth decay is an infectious disease that afflicts the majority of Americans aged 55 and older and is the most common chronic disease at midlife with an ever growing economic toll. Despite the fact that specific bacteria cause tooth decay, no FDA-approved anti-microbial treatment for decay is available to the American dental professional. The Prevention of Adult Caries Study (PACS) is a study is designed to evaluate the efficacy of a topical, temporary, 10% w/v chlorhexidine dental coating in reduce new decay in adult dental patients at risk for decay.

Adult dental caries, including both coronal and root caries, is an infectious disease that afflicts the majority of Americans aged 55 and older and is the most common chronic disease at midlife. In addition, adult caries wreaks a significant economic toll, and this economic toll continues to grow. Despite the high prevalence and bacterial pathogenesis of caries, no FDA-approved anti-microbial treatment for caries is available to the American dental professional. The Prevention of Adult Caries Study (PACS) is a randomized, double-blind, placebo-controlled Phase III clinical trial conducted under F.D.A. Investigational New Drug license #45,466. This study is designed to evaluate the efficacy of a topical, temporary, 10% w/v chlorhexidine dental coating in reducing caries increment in at-risk adult dental patients. This study will follow 1000 patients over a 13-month study period at four centers with vastly diffent populations. The primary endpoint for this study will be caries increment. The centers participating in this proposed reaserch are: Kaiser Permanente's Dental Plan in Portland, Oregon; Tufts University Dental Clinic in central Boston, Massachusetts; Delta Dental Massachusetts' Dental Clinic in Southborough, Massachusetts; and the dental clinic of the Tuba City Regional Health Care Corporation in Tuba City, Arizona. Kaiser Permanente's Center for Health Research in Portland, Oregon will act as the data-coordinating center, and Tufts University will act as the Administrative Center.

Inclusion Criteria:

• 18 years of age and older
• at least 20 intact natural teeth, excluding third molars
• 2 or more lesions, of which at least one must be a cavitated D2 or D3
• willing and able to provide informed consent

Exclusion Criteria

• pregnant or planning to become pregnant or planning to become pregnant during the study (breastfeeding is permitted)
• use of fixed orthodontic appliances
• allergic to any of the ingredients of the study medication
• long-term antibiotic therapy
• a history of, or currently active, radiation therapy for cancers of the head or neck
• Sjögren's syndrome
• advanced periodontitis
• consumption of the equivalent of more than five servings of acidic or sugared drinks per day
• having 10 or more lesions requiring restorative care at the time of the screening visit
• remineralization therapy within one month of randomization
• investigator discretion