Table 2.

Three data sets were acquired each day for five consecutive days from six subjects to determine the repeatability of our device; we assume the health of each subject remained constant across the week. The standard deviation of the 15 measurements for each subject is listed, as well as the standard deviation across all measurements taken from subjects with varying degrees of gingival health (Concorde Clinic). Levene’s test for equal variance was applied to compare the variance of each subject to the collective data from Concorde Clinic, and the variances were significantly different ($p<0.05$). This indicates that the variations in contrast due to daily changes in perfusion and instrument noise are significantly less than variations in flow due to different degrees of gingival health.

Subject	Standard deviation ($\sigma$)	$p$-value of ${\sigma }_{\text{repeatability}}$ compared to ${\sigma }_{\text{Concorde}}$
Repeatability 1	0.008	0.008
Repeatability 2	0.007	0.004
Repeatability 3	0.014	0.048
Repeatability 4	0.011	0.015
Repeatability 5	0.008	0.009
Repeatability 6	0.011	0.021
Concorde Clinic	0.021	—