Laser Doppler flowmetry of luxated permanent incisors: a receiver operator characteristic analysis

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood-flow (PBF). Dental luxation injuries have been associated with significant PBF reduction. The purpose of this study was to describe diagnostic characteristics for different session-related threshold PBF values for detection of specific adverse outcomes. In 61 trauma patients, a single maxillary incisor treated by repositioning and splinting, and the respective contralateral homologous control tooth were investigated by LDF to assess local PBF values. Perfusion units (PU) were taken 12 weeks (session I) and 24 weeks (session II) after splint removal. The ability of session I-related PBF measurements at 2.8, 6.4 and 10.1 PU levels, and of session II-related ameasurements at 2.4, 6.3 and 10.2 PU levels to identify adverse outcomes occurring 36 weeks after splint removal was investigated. Adverse outcomes were classified as type I (periapical radiolucency), type II (grey discoloration), and type III (periapical radiolucency and grey discoloration of crown). Receiver operator characteristic curves were used to evaluate the sensitivity and specificity of PBF assessments. There was no significant difference in PBF values between session I and session II (P > 0.05) for teeth without an adverse outcome, and those with a type I, II or III outcome (P > 0.05). The PBF measurements did not change over time for the contralateral incisors (P > 0.05). A type I, II and III outcome occurred in 36, 21 and 12% of the incisors, respectively. The best likelihood ratio was found for the PBF 6.4 PU level at session I and incisors associated with a type I (20.8) and type II outcome (15.2). The PBV of 6.4 PU demonstrated a sensitivity of 96% and a specificity of 59% for type I outcomes, and a sensitivity of 100% and a specificity of 50% for type II outcomes. The data suggest the LDF test to be a valuable diagnostic adjunct for luxated teeth showing signs of adverse outcomes.