BIRTA ORSOLYA BEATA, CRISTINA BICA, FARKAS HUNOR PAL, BERNADETT KEREKES MATHE, ANDREEA BORS,MELINDA SZEKELY THE IMPACT OF THE PHOSPHORIC ACID ON CALCIUM CONTENT OF DENTAL ENAMEL - IN VITRO EXAMINATION This study is intended for testing the way and extent how various acids influence dental erosion. Impacted third molar teeth removed under surgical exploration have been used in our experiments. The test samples have been prepared based on the Semmelweis University Dental Care Clinic protocol. Then the organic material has been removed using incubation solutions. Every 6 hours, the calcium concentration has been measured using a Radelkis OP- 274 Ph-ionometer and an OP-Ca-0711P-S type electrode sensitive to calcium ions, strictly following the manufacturer’s instructions. Data were statistically processed in Graphpad InStat 3 (Graphpad Software Inc, CA, USA) using paired T-test and ANOVA. The results contradict several articles published in the scientific literature dealing with this subject and describing the linear dependence between the dental erosion progress and time. Our study emphasized that the erosion process progressed in time, however it failed to show a linear dependence.