STUDIA UBB CHEMIA, LXIV, 4, 2019 (p. 93-105) (RECOMMENDED CITATION) DOI:10.24193/subbchem.2019.4.07 EFFECT OF AN EXPERIMENTAL GREEN TEA EXTRACT BLEACHING GEL ON THE COLOR CHANGES OF A COMPOSITE RESIN CORINA VOINA a , ADRIANA MURESAN b , ADA DELEAN a , AMALIA IONELA MOLDOVAN c , LAURA SILAGHI DUMITRESCU d* , ANDRADA VOINA TONEA e , MADALINA VALEANU f ABSTRACT. The effect of the color change of stained and then bleached composite resins blocks have been evaluated. 28 blocks, made from Admira fusion composite resin and divided in 3 groups, were included in the present study. They were stained in coffee for 3 days and then bleached with Opalescence gel (GO) and experimental bleaching gel based on green tea extract (GE). All color indices were measured in all situations (initially, after staining and after bleaching) with Vita Easy Shade spectrophotometer. It was used the CIE*L*a*b system for the color change parameters. The group bleached with Opalescence presented the most significant color changes. The bleaching effect of the experimental gel is lower that Opalescence bleaching gel. Keywords: green tea, composite blocks, staining, bleaching, color change a Department of Odontology and Oral Pathology, Faculty of Dental Medicine, University of Medicine and Pharmacy “Iuliu Hațieganu”, 33 Motilor Street, 400001, Cluj-Napoca, Romania b Department of Functional Sciences, Faculty of Medicine, University of Medicine and Pharmacy ”Iuliu Hatieganu”, 3 Clinicilor Street, 400006, Cluj-Napoca, Romania c Physics and Chemistry Department, Technical University of Cluj-Napoca, 28 Memorandumului Street, Cluj-Napoca 400114, Romania d Babes Bolyai University -”Raluca Ripan” Chemistry Research Institute, 30 Fântânele Street, 400294,Cluj-Napoca, Romania e Department of Dental Matherials, Faculty of Dental Medicine, University of Medicine and Pharmacy”Iuliu Hatieganu”,15 Babes Victor Street,400012, Cluj-Napoca, Romania f Department of Medical Informatics and Biostatistics, Faculty of Medicine, University of Medicine and Pharmacy ”Iuliu Hatieganu”, 6 Pasteur Louis Street, 400349, Cluj-Napoca, Romania * Corresponding author: lauraiulia2000@yahoo.com