Pilot Study on the Usefulness of Quantitative Light-Induced Fluorescence-Digital for Dental Plaque Assessment in a Rat Model of Periodontitis

Objective: This study quantifies dental plaque in an animal periodontitis model using quantitative light-induced fluorescence-digital (QLF-D), providing fundamental data for establishing diagnostic criteria for periodontitis. Methods: Periodontitis was induced by ligating the mandibular first molars of Sprague–Dawley rats. After 18 days, QLF-D images showing the plaque on the ligatures were obtained intraorally before sacrifice and extraorally after sacrifice. The red and blue fluorescence values were measured using software, and the average red/blue (R/B) ratio was calculated for each image. Alveolar bone loss was evaluated histologically. Results: Ligation of the first molars resulted in an increase in the periodontal ligament area compared to that of the control group, demonstrating alveolar bone resorption. The extraoral lingual-side images obtained after sacrifice were reproducible and provided clear assessment criteria. The R/B ratio of the plaque accumulated on the ligatures was 1.9±0.3. Conclusions: Plaque formation, which is difficult to assess by visual inspection alone, can be evaluated using QLF-D. The animal model of periodontitis used in this study can be used to obtain preclinical data to develop future preventive and therapeutic strategies for periodontal diseases.