The purpose of this study was to evaluate the applicability of auto-fluorescence imaging system to detect and quantify caries and dental plaque. Participants were advised to rinse their mouth with distilled water to exclude any chance of fluorescence from food debris. A well trained physicist majored in optical spectroscopy captured auto-fluorescence images of buccal aspects of two maxillary central incisors and occlusal aspects of four first molars from each patient in a dark room. Then they chewed a disclosing agent to assess the Quigley Hein plaque index modified by Turesky of each tooth. Furthermore, participants were also required to brush their teeth for 3min, then International Caries Detection and Assessment System（ICDAS）codes of relevant teeth to evaluate degrees of caries were recorded by an experienced dentist using a mouth mirror and explorer. The Spearman rank correlation coefficient between colorimetric parameters of fluorescence image and the plaque index and ICDAS code were calculated to evaluate the sensitivity and specificity of auto-fluorescence imaging system.

Inclusion Criteria:

Subjects were required to:

• 1. have two maxillary central incisors and four first molars in mouth;
• 2. have caries in their mouth or have a high risk to get caries and need to be treated by dentists ;
• 3. sign informed consent form.

Exclusion Criteria:

• 1.two incisors and four first molars of participants ever received endodontics treatment;
• 2. history of antibiotics, mouthwashes, or any periodontal treatment during the last 3 months;
• 3.with calculus and cementum exposed in tooth cervical;
• 4. active systemic disease;
• 5. physical or mental disability;
• 6. pregnant or lactating.

The study population consisted of 60 patients are from the Affiliated Stomatology Hospital of Medical College, Zhejiang University. They have caries in their mouth and need to be treated by dentists with filling cavity. Two maxillary central incisors and four first molars exist in each patient.