Table 3.

Internal consistency reliability through the ordinal coefficient alpha.

Scales and Cytokine Concentration in Salivary Samples	Statistic	Sample
		DP (n = 35)	HMP (n = 26)	Pooled (n = 61)
BDI-II (21 items)	ordinal α	0.874	0.856	0.957
OHHS (8 items)	ordinal α	0.802	0.913	0.861
OHIP-14-PD (14 items)	ordinal α	0.912	0.936	0.923
IL-1β	r [95% CI]			0.998 [0.994, 1]
IL-6	r [95% CI]			0.999 [0.997, 1]
MMP-8	r [95% CI]			0.972 [0.955, 1]

Note. Sample: DP = dental patients with periodontitis, MHP = mental health patients with depressive symptomatology, and Pooled = union of the two patient samples. Scales: BDI-II = total score in Beck Depression Inventory-II, OHHS = total score in Oral Hygiene Habits Scale, and OHIP-14-PD = total score in the Oral Health Impact Profile applied to Periodontal Disease. Cytokines: IL-1β = salivary interleukin 1 beta concentration, IL-6 = salivary interleukin 6 concentration, and MMP-8 = salivary matrix metalloproteinase-8 concentration. Statistic: n = sample size, ordinal α = standardized coefficient alpha calculated from polychoric correlation matrix, r = Pearson’s product-moment correlation coefficient between eight levels of serial dilutions of the antibody concentration (0, 3.125, 6.25, 12.5, 25, 50, 100, and 200 pg/mL for IL-1β; 0.156, 3.125, 6.25, 12.5, 25, 50, and 100 pg/mL for IL-6; and 0, 78, 156, 313, 625, 1250, 2500, and 5000 pg/mL for MMP-8) and the average absorbance (negative of the logarithm with base 10 of quotient between incident and transmitted light intensities). Concentration and absorbance values are only available for each microplate; since the microplate of each cytokine test has 96 wells, both patient samples were joined and, therefore, correlations could only be calculated in the pooled sample. CI = confidence interval calculated through percentile bootstrapping method with the simulation of 1000 random samples.