Intensity vs. time curves for the two lesions shown in Figs. 3 & 4 are plotted in Fig. 5 for both the benchtop and handpiece systems. The active lesion exhibits a measurable delay before the rapid sigmoidal rise in intensity that reaches the maximum intensity in only 12 seconds for the benchtop system and is even faster for the handpiece where it takes about 8 seconds to peak. In contrast the arrested lesion exhibits no discernable delay. The intensity slowly rises and does not achieve peak intensity after 60 seconds. Mean ± sd of delay, ΔI%, %Ifin, and rate after 60 seconds of drying for the active (n=10) and arrested (n=10) lesion areas are tabulated in Table I for both the benchtop and handpiece systems. The significance level calculated from unpaired two-tailed t-tests between the active and arrested groups for each system is also listed. The means of delay, %Ifin, and rate were significantly different between active and arrested lesions for both the benchtop system and the handpiece. Active lesions had a significantly higher mean ΔI% than arrested lesions for the benchtop system while there was no significant difference between the two groups with the handpiece. 3D scatterplots of delay, %Ifin, and rate for the active lesions (red) and arrested lesions (blue) are shown in Fig. 6 for the benchtop and handpiece systems. There is clear separation in grouping in the 3D plots between the active and arrested lesions for both systems.
Differentials in the magnitude of the means between active and arrested lesions for delay, %Ifin, and rate all exceeded ratios of 5 to 1 with rate being the highest at 9 to 1.