Estimation of periodontal inflamed surface area by salivary lactate dehydrogenase level using a test kit

Abstract Salivary lactate dehydrogenase (LD) level is a feasible and useful parameter for screening periodontal diseases. The periodontal inflamed surface area (PISA) is a useful index for clinical and epidemiological assessments. However, PISA is extremely difficult to calculate and PISA-compatible screening kits are required. We aimed to investigate the association between salivary LD level, using a test kit, and the PISA and PISA-Japanese, and determine the feasibility and reliability of the salivary LD test kit for evaluation of periodontal status. The study included 110 patients (66.4% female, median and 25–75 percentiles of age were 66.5 and 53.0–75.0 years, respectively) who visited the Dental University Clinic in Japan. Resting saliva samples were collected from each participant, and LD levels were evaluated in real-time using a kit featuring an integer scale ranging from 1 to 10. PISA and PISA-Japanese were calculated using periodontal parameters. The median of salivary LD level was 4.0. The medians of PISA and PISA-Japanese were 46.9 and 61.0, respectively. Salivary LD level was positively correlated with bleeding on probing rate (r = 0.626, p < 0.001), PISA (r = 0.560, p < 0.001), and PISA-Japanese (r = 0.581, p < 0.001). Our results suggest that salivary LD levels assessed using the salivary LD kit showed a significantly positive correlation with PISA and PISA-Japanese. In addition, we developed the PISA estimation formula using salivary LD level with a test kit, sex, and age.