Correlation of ICDAS Score and NMR, ICP-OES Saliva Composition

Objectives: Dental caries prevalence is strongly related to saliva composition. The aim of this study was to use two sophisticated analytical chemical tools ¹H-Nuclear Magnetic Resonance Spectroscopy (¹H-NMR) and Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES), to identify and measure the concentration of organic and inorganic components of healthy adults saliva, in relation to dental caries prevalence.
Methods: Parotid saliva samples from 8 patients were collected using a Lashley cup during chewing. The flow-rate was recorded. Clinical caries scores of each patient were classified using the International Caries Detection and Assessment System (ICDAS). Each saliva sample was analysed using ¹H-NMR and ICP-OES to determine the organic and inorganic composition. Principal Component Analysis (PCA) was used to detect variances of features (peaks) within all the ¹H-NMR spectra. ICP-OES analysis was used to detect elements including: Ag, Al, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, In, K, Li, Mg, Mn, Na, Ni, P, Pb, Si, Sr, TI, Zn, P, and Si. ICDAS and ICP-OES results were statistically analysed by Pearson’s Correlation.
Results: Salivary flow rates were 0.10 to 0.42ml/min. The ICDAS cumulative score was from 0.07 to 0.86. The PCA score plot indicated the ¹H-NMR spectra differed at peak position 2.23ppm assigned to the acetone chemical shift. A high acetone peak was associated with a high individual ICDAS score. ICP-OES analysis revealed that the concentration of elements was: Al 0.83-0.91ppm; Ba 0.03-0.04ppm; Ca 3.8-8.7ppm; Cr 0.08-0.09ppm; K 18.41-54.12ppm; Li 0.76-0.80ppm; Mn 0.44-0.49ppm; Na 7.82-25-33ppm, Sr 0.38-0.44ppm; Zn 0.14-0.19ppm. Other elements concentrations were below the detection limit (<0.5ppm). The most significant correlation of ICP-OES and ICDAS score was for zinc (R=-0.754; p-value=0.031).
Conclusions: The use of ¹H-NMR and ICP-OES in conjunction with ICDAS provides comprehensive analysis of saliva composition in relation to dental caries.