Optimisation of Laser Doppler Flowmetry to detect pulpal blood flow in permanent maxillary Incisor Teeth

Abstract

Background: Traumatised teeth can present a challenge in diagnosis where pulp sensibility tests and radiographic findings can occasionally be unclear or unreliable, especially in children. Pulp vitality testing through laser Doppler flowmetry (LDF) provides objective, painless, and quantitatively monitors pulp blood perfusion instead of relying on subjective sensibility pulp tests and the child’s responses.

Aim: To evaluate the clinical utility of LDF in determining reliable pulpal blood flow (PBF) signals in healthy, traumatised, and non-vital mature permanent maxillary incisor teeth, and to establish a diagnostic protocol in the Dental Centre Department in St Thomas’ Hospital.

Methods and design: LDF measurements of PBF in maxillary incisors were taken using the MoorVMS-LDF1 instrument. Participants had either traumatised or root canal-treated incisors alongside contralateral healthy incisors, and a control group with healthy incisors. A silicone stent was used to stabilise the LDF probe. This project measured mean flux values, sensitivity, specificity, flux cut-off value, PBF measurements distribution across the vital and non-vital ranges, and the repeatability of LDF tests. Statistical analysis included descriptive statistics, the Kruskal-Wallis test (P >0.05), receiver operating characteristic (ROC) analysis, and interclass correlations coefficient (ICC).

Results: 21 participants aged 12 to 59 years old (mean age =24.24 ±13.56) had their 42 permanent maxillary incisors tested. A total of 84 PBF measurements were categorised into three groups: vital/control (n = 62), trauma (n = 14), and non-vital/root canal-treated (n = 8). The mean PBF values of the trauma group were similar to the mean PBF values of the vital/control and non-vital/root canal-treated groups (P = 0.137). Specifically, participants with a healthy tooth and a contralateral traumatised tooth showed no significant difference in mean PBF values (P = 0.182). However, participants with a healthy tooth and a contralateral non-vital root-treated tooth exhibited a significant difference in mean PBF values (P = 0.009). ROC analysis comparing vital and non-vital pulps showed a sensitivity of 87.5% and a specificity of 69.4%. The analysis identified a cut-off value of 4.65 flux and an area under the curve of 0.693, P = 0.031 with a 95% confidence interval of 0.517–0.868. All LDF tests showed good repeatability in measuring with an ICC of 0.785.

Conclusion: LDF fails to differentiate non-vital from vital pulps accurately and it cannot distinguish between vital and non-vital pulp readings among traumatised incisors. Although the device used is marketed to assess pulpal blood flow, further optimisation is required before clinical implementation