Reproducibility of facial skin and mandibular gingival laser Doppler flowmetry

Objectives: Laser Doppler flowmetry (LDF) is a widely used non-invasive technique for assessing microvascular blood flow. Vasodilatation can be induced by heat probes. Standardized procedures including thermal status may increase reproducibility and thereby the feasibility of LDF for longitudinal studies. This has not been investigated in gingival tissue and there are few studies of facial skin. The aim of this study was to evaluate the reproducibility of facial skin and mandibular gingival LDF and to study the responses to nicotine and beta-adrenergic antagonists.

Methods: Ten healthy adults (5 men) aged 31-68 years volunteered to participate. Gingival perfusion was recorded with the LDF probe fixed to a custom made tooth supported acrylic splint. Skin perfusion was recorded at a predetermined location on the cheek. Measurements were performed in the morning and afternoon on day 1 and repeated in the morning after one week and six weeks. The effect of nicotine (Nicorette® nasal spray) and beta-adrenergic antagonists (Pranolol®) were tested on separate visits.

Results: LDF results obtained after vasodilatation by heat provocation had a better reproducibility than basal flow readings in both facial skin and mandibular gingiva. Large intraday variations were seen. Interweek reproducibility was within acceptable limits with the largest variability found in basal flow of facial skin. Basal flow of facial skin was significantly reduced after intake of a beta-adrenergic antagonist (p=0,03). After using nicotine there was a tendency for an increased gingival flow by local heating (p=0,06).

Conclusion: LDF is acceptably reproducible for use in longitudinal studies where subjects serve as their own control. It is recommended that repeated measurements are made at the same time of day and that probes inducing vasodilatation by local heating are used. The sensitivity of LDF is sufficient to detect effects of low doses of nicotine and beta-adrenergic antagonists.