Objectives: Several methods are clinically available to indirectly test the vitality of human tooth pulp tissue in vivo. Pulse signals detected directly from the pulp might be considered reliable for an objective assessment of pulp vitality. A recently presented tooth model (J Dent Res 87[Spec Iss C],82.2008) was further developed simulating a simultaneous bloodflow in the gingiva and the tooth. The purpose of this study was to test the influence of gingival signals on blood flow in the tooth.
Methods:
A custom-built photoplethysmograph (PPG) using a 625nm light emitting diode, indirectly adapted to the tooth-gingivamodel (TGM) via fiberoptics was used. Emitter and detector holders were applied lingual-buccaly to the tooth-pulp model and connected to the PPG. Pulse measurements were performed for human blood flowing through (i) tooth only, (ii) gingiva only, and (iii) alternately through tooth and gingiva with a frequency of 2 Hz, using a custom-built dual channel pulsepump. An aluminium foil was used to shield pulse signals from the pulp from those of the simulated gingiva. (n=6; non-parametric statistical analysis, a=0.05; Test Parameter ΔU := maximum – minimum of PPG Signal [V] ).
Results:
ΔU (Medians(25-75% Percentiles)):
Blood flow through | aluminium foil | |
| no | yes |
tooth | .6400(.6100-.7025) | .3200(.2975-.3225) |
gingiva | .2200(.2200-.2300) | .1800(.1800-.1900) |
tooth and gingiva | .8050(.7450-.8550) | .4000(.3825-.4250) |
Significantly higher signals without aluminium foil suggested that signals from the root and gingival parts of the tooth model influenced the measurements.
Conclusions:
The TGM seems to be a reliable model for detecting blood flow through a tooth surrounded by a blood carrying gingival model. Even though an increased signal was detected when blood was flowing through tooth and gingiva, the main part of the signal origined from the pulpal part.
(Supported by a grant from Deutsche Forschungsgemeinschaft, SCHM 386/3-1)