Evaluation of a new device to measure dentin permeability

Objectives: To evaluate a new electronic device to measure dentin permeability (Lp).

Methods: The flowmeter ASL1600 (Sensirion, Switzerland) is a new electronic device based on a thermal chip that detects liquid mass flow from changes in thermal gradients. An initial test at 70 cm H₂0 was performed to compare fluid flow values of human acid-etched (H₃PO₄ 15sec) crown segments alternatively tested with the new Flowmeter and with the much older Flodec (DeMarco Engineering, Geneva, Switzerland). After flow rates were measured using the Flowmeter in 20 acid-etched crown segments, the flow rates were reevaluated with the Flodec. Fluid flow, expressed in �l/min, was recorded for 5 minutes for each specimen, after a steady permeability had been reached.�

Results: Dentin permeability values obtained by Flowmeter and Flodec were compared. Flodec gave values that were 19.7� 4% higher values compared to those recorded at the same pressure with the Sensirion.� However, the standard deviation of the flow rates of the Flodec were 5.6 times higher than the Flowmeter. When Flowmeter data were plotted against Flodec data, a significant correlation was found (r=0.91).�

Conclusions: The Sensirion solid-state device represents a simple, accurate, reliable instrument to measure the fluid flow rate across the dentine. It is less expensive than the Flodec device and should be more reliable because it contains no moving parts. �

Flodec Sensirion	Fluid flow (�L/min) at 70 cm H2O (mean � SD, CV)
	Mean � SD	% diff	CV	Difference
	3.05 � 0.78	--	0.0066	4.13
	2.43 � 0.55	19.8	0.016	--