Electrical Impedance Mapping of Healthy Oral Mucosa

Abstract

Električna impedancija (EI) je otpor prolasku izmjenične električne struje kroz tkivo. EI ovisi o promjenama strukture i kemijskom sastavu tkiva, te se stoga koristi u dijagnostičke svrhe, ponajprije kožnih promjena. Primjena EI za dijagnostiku na oralnoj sluznici nije dovoljno znanstveno evaluirana. Svrha rada bila je utvrditi referentne vrijednosti EI na zdravoj oralnoj sluznici, te evaluirati izvedivost i ponovljivost metode. Svrha rada je također bila utvrditi utjecaj demografskih i kliničkih faktora (spol, dob, pušenje, količina sline, pritisak elektrode) na vrijednosti EI. U istraživanju je sudjelovao 101 ispitanik. Ispitanici su bili podijeljeni u tri skupine: 20-40 godina, 40-60 godina i preko 60 godina. Vrijednosti EI mjerene su posebno konstruiranim uređajem tri puta u razmaku od po tjedan dana na 14 mjernih točaka u usnoj šupljini (po 7 točaka na lijevoj i desnoj strani). Najviše vrijednosti EI zabilježene su na sluznici tvrdog nepca, a najniže na dorzumu jezika. Nisu utvrđene statistički značajne razlike u vrijednostima EI između lijeve i desne strane. Vrijednosti EI smanjivale su se s dobi ispitanika. Vrijednosti EI u žena bile su značajno više nego u muškaraca. Nepušači su imali statistički značajno više vrijednost EI samo na sluznici gornje usne. Količina sline nije imala utjecaja na izmjerene vrijednosti. Pritisak elektrode na sluznicu utječe na izmjerene vrijednosti-primjenom višeg podtlaka izmjerene su statistički značajno niže vrijednosti. Nisu utvrđene statistički značajne razlike između pojedinih mjerenja kod svakog ispitanika. Primjenom opisane metode moguće je izmjeriti vrijednosti EI na svakoj točki oralne sluznice. Metoda je jednostavna i lako primjenjiva, te daje ponovljive i stabilne rezultate.Electrical impedance (EI) is the resistance to the flow of alternating electric current through a tissue. It is dependent on the structure and the chemical composition of the tissue and is therefore used for diagnostic purposes, primarily for changes in the skin. Application of EI in diagnostics related to the oral mucosa has not been sufficiently evaluated scientifically. The purpose of the study was to determine the reference values of EI on healthy oral mucosa, and to evaluate the feasibility and reproducibility of the method. The aim also was to determine the effect of demographic and clinical factors (gender, age, smoking, amount of saliva, pressure of the electrode) on EI values. The study included 101 subjects divided into three groups: 20-40 years, 40-60 years and over 60 years. Inclusion criteria were clinically normal oral mucosa and the ability to read and understand the text of the informed consent. EI values were measured by a specially designed device three times at one-week intervals at 14 measuring points in the oral cavity (7 points on its left and right side, respectively). The intraoral sensor consisted of a system of concentric electrodes that adhered to the mucous membrane through application of varying degrees of negative pressure (250° or 350 MB). It was connected to the measuring device NI USB-6251 (National Instruments®, Austin, USA) connected via USB to a laptop. The measurement programme developed on the basis of the LabView 8.5.1. software package (National Instruments®, Austin USA) converted the electrical impulses from the device into digital records and stored them in the database. Statistical analysis was performed using the SPSS ver. 20 software (IBM Inc, USA). The highest values of EI were recorded on the mucosa of the hard palate, and the lowest on the dorsum of the tongue. No statistically significant differences in EI values between the left and right side were established. EI values were found to decrease with age, and to be significantly higher in women than in men. This finding needs to be verified and clarified in future research. In nonsmokers, significantly higher EI values were found only in the mucosa of the upper lip. The amount of saliva had no effect on the measured values. The pressure exerted on the mucous membrane by the electrode did affect the measured values - applying higher negative pressure resulted in statistically significantly lower values. No statistically significant differences were found between individual measurements in any of the subjects. The method described in the study makes it possible to measure EI values at each point of the oral mucosa. The method is simple and easily applicable, and provides reproducible and stable results, which in turn opens the possibility of using it for non-invasive differentiation of healthy oral mucosa from various pathological conditions