Lasers in Medical Science

, Volume 33, Issue 9, pp 1891–1900 | Cite as

Diurnal variations and pulpal status: is there a need for FFT besides LDF?

  • Herman J.J. Roeykens
  • Roeland J.G. De Moor
Original Article


The aim of this article was to investigate the use of laser Doppler flowmetry (LDF) combined with a fast Fourier transformation (FFT). LDF data in relation to three different scenarios were evaluated: (a) LDF records of a right central upper incisor of one patient were used for FFT analysis. These records were obtained by means of 30 pre-manufactured splints, handled by dentists without any experience in LDF recording. (b) Diurnal variations in one patient were analysed with LDF and FFT using 11 splints by one and same experienced investigator at four specific moments of the day. (c) Pulpal status was analysed using 17 splints. Eleven for a patient, standing as case model and six splints for six other patients. In this specific group, each patient had one vital and one non-vital central maxillary incisor and was analysed separately by LDF and FFT. The data of assessment (b) showed diurnal variations on LDF values of almost 80%, indicating that LDF registration is best performed in the same time period of the day. Data verification with FFT confirmed the findings without FFT of assessment (a) and (b). In assessment, (c) FFT demonstrated a clear distinction between a vital and a non-vital pulp for those cases with one vital tooth and one root canal treated tooth. In those cases with one vital incisor and the other traumatised, FFT was undeterminated. Considered that FFT was obtained after LDF recording and remained undeterminated for a decision in cases with decreasing pulpal blood flow in time, the added value of FFT in pulpal traumatology was minimal.


Circadian rhythm Diurnal variations Laser Doppler flowmetry Pulpal blood flow Vitality test Fast Fourier transformation (FFT) 



Dr. Rodney Gush (Moor Instr., Axminster, UK). Dr. Ellen Deschepper (Biostatistics Unit, Ghent University, Belgium).

Compliance with ethical standards

Conflict of interests

The authors declare that they have no conflict of interest.

Ethical approval

The authors declare that the protocol of this article was approved by the Ghent University Hospital Ethical Committee, 2016/1525.


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Copyright information

© Springer-Verlag London Ltd., part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Reconstructive Dentistry and Endodontology, Ghent Dental Laser Centre, Ghent Dental Photonics Research Cluster, Dental School, Ghent University HospitalGhent UniversityGhentBelgium

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