Mai FukuyamaChiharu KawamotoPipop SaikaewYasuhiro MatsudaRicardo M. CarvalhoDenis SelimovicHidehiko SanoHokkaido UniversityMahidol UniversityHealth Sciences University of HokkaidoThe University of British Columbia2018-12-212019-03-142018-12-212019-03-142017-12-01European Journal of Oral Sciences. Vol.125, No.6 (2017), 471-47816000722090988362-s2.0-85033459569https://repository.li.mahidol.ac.th/handle/20.500.14594/42428© 2017 Eur J Oral Sci This study evaluated the effect of topical fluoride application on enamel hardness after in-office bleaching. Twelve human incisors were cut along the long axis, resulting in 24 halves used in four treatment groups (n = 6 in each group): (i) untreated group (C); (ii) in-office bleaching material (B); (iii) treatment with surface reaction-type prereacted glass-ionomer varnish after in-office bleaching (B+PRG); and (iv) treatment with acidulated phosphate fluoride solution after bleaching (B+F). All specimens were subjected to pH-cycling for 4 wk. Knoop hardness was measured using a Cariotester. The decalcification of enamel was assessed quantitatively by measuring the integrated mineral loss (ΔIML). Games–Howell analysis was used to assess statistical significance of between-group differences. The Knoop hardness decreased significantly after bleaching for all groups. In treatment groups B+PRG and B+F, the Knoop hardness returned to the original unbleached values after the first pH cycle and did not change afterwards. In treatment groups C and B there was a gradual decrease in the Knoop hardness until the fourth pH cycle. The integrated mineral loss, ΔIML, was significantly higher in treatment group B+F after 2 wk than in the other treatment groups. After 4 wk, the ΔIML in treatment group B was significantly higher than in treatment group B+PRG. The application of fluoride-containing materials after bleaching results in recuperation of hardness to levels similar to those of unbleached enamel.Mahidol UniversityDentistryArticleSCOPUS10.1111/eos.12386