Diagnostic characteristics of pulpal blood flow levels associated with adverse outcomes of luxated permanent maxillary incisors.

Laser Doppler flowmetry (LDF) is a non-invasive method to assess pulpal blood flow (PBF). Dental injury has been associated with significant PBF reduction. The purpose of this study was (i) to describe PBF characteristics of teeth with specific clinical outcomes, and (ii) to demonstrate diagnostic characteristics for different threshold PBF values for detection of specific multiple adverse outcomes. In 80 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 in two sessions, on the day of splint removal (session I), and 12 weeks after splint removal (session II). The ability of session II-related PBF measurements at 2.9, 6.4 and 9.9 PU levels to identify adverse outcomes occurring 36 weeks after splint removal was investigated. Adverse outcomes were classified as type I (loss of sensitivity), type II (periapical radiolucency), type III (grey discolouration), type IV (loss of sensitivity and periapical radiolucency), and type V (loss of sensitivity, periapical radiolucency and grey discolouration of crown). Receiver-operator characteristic (ROC) curves were used to evaluate the sensitivity and specificity of PBF assessments. There was a significant increase in PBF values from session I to session II (P=0.0001) for teeth without an adverse outcome, while teeth affected by a type II-V outcome showed a significant decrease in PBF values (P <0.05). PBF measurements did not change over time for the contralateral incisors (P >0.05). A type IV and V outcome occurred in 21 and 24% of the instances, respectively. The PBF of 2.9 PU demonstrated a sensitivity of 70% and a specificity of 93% for type V outcomes. The best likelihood ratio was found for the PBF 2.9 PU level and incisors associated with a type V outcome. The data suggest that the LDF test to be a valuable diagnostic adjunct for luxated teeth showing signs of adverse outcomes including grey discolouration or a combination of other signs. However, it may also become necessary to apply clinical decision-making methods in order to correctly evaluate the value of information gathered. The clinical implication is that LDF may become useful in the prediction of adverse outcomes at a much earlier time period than may be accomplished by standard sensitivity tests.