Citation: Ergucu, Z.; Yoruk, I.; Erdo ˘ gan, A.; Boyacıo ˘ glu, H.; Hill, R.; Baysan, A. The Use of Toothpastes Containing Different Formulations of Fluoride and Bioglass on Bleached Enamel. Materials 2023, 16, 1368. https://doi.org/10.3390/ ma16041368 Academic Editor: Bongju Kim Received: 27 December 2022 Revised: 19 January 2023 Accepted: 28 January 2023 Published: 6 February 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). materials Article The Use of Toothpastes Containing Different Formulations of Fluoride and Bioglass on Bleached Enamel Zeynep Ergucu 1 , Inci Yoruk 1 , Ay¸ segül Erdo ˘ gan 2 , Hayal Boyacıo ˘ glu 3 , Robert Hill 4 and Aylin Baysan 4, * 1 Departmentof Restorative Dentistry, Faculty of Dentistry, Ege University, 35040 Izmir, Türkiye 2 Ege University Application and Research Center for Testing and Analysis (EGE MATAL), Ege University, 35040 Izmir, Türkiye 3 Department of Statistics, Faculty of Science, Ege University, 35040 Izmir, Türkiye 4 Centre for Oral Bioengineering, Barts and the London School of Medicine and Dentistry, Queen Mary University, London E1 2AD, UK * Correspondence: a.baysan@qmul.ac.uk Abstract: Objectives: To investigate the application of toothpaste either containing calcium sodium phospho-silicate bioglass (NovaMin) or calcium fluorosilicate bioglass (BioMinF) on the surface min- eral composition and morphology of enamel after bleaching procedure. Methods: Thirty extracted noncarious human teeth were allocated into five groups (n = 6). Group 1: Bleaching using 40% hydrogen peroxide (HP) and fluoridated toothpaste containing bioactive glass (1450 ppm fluoride). Group 2: Bleaching using 40%HP and toothpaste containing calcium fluorosilicate bioglass (540 ppm fluoride). Group 3: Bleaching using 40%HP and fluoridated toothpaste (1450 ppm fluoride). Group 4: Bleaching alone using 40%HP. Group 5: Negative control with distilled water alone. The sur- face morphology was evaluated using Scanning Electron Microscope (SEM) and Scanning Probe Microscope (SPM). The concentration of elements as atomic percentages were determined by X-ray Photoelectron Spectroscopy (XPS) and Energy-Dispersive X-ray Spectroscopy (EDS). Results: This laboratory-based study reported that SPM and SEM detected minor changes on the surfaces of all toothpaste-treated enamel samples (Groups 1–3) after 45 days. Bioactive glass deposits were observed on enamel surfaces in Groups 1 and 2, whilst the bleaching-alone samples (Group 4) had rough enamel surfaces. XPS reported that toothpaste containing calcium fluorosilicate bioglass (Group 2) had a high atomic% of calcium and phosphate, whilst silicon values were high in the toothpaste containing bioactive glass and 1450 ppm fluoride (Group 1) after bleaching procedure when com- pared to other groups (p < 0.05). In addition, EDS detected the highest %F in Groups 1, 2 and 5. Conclusions: Within the limitations of this laboratory-based study, there was no significant decrease in the Ca%, P% values and surface properties of enamel after the bleaching procedure following the use of different formulations of toothpastes for a period of 45 days. However, the Ca% and P% values were significantly high for the toothpaste containing calcium fluorosilicate bioglass (BioMinF) on the bleached enamel. Clinical relevance: The bleaching process can provide optimum aesthetic outcomes, but the effect of peroxides on hard tissues is still in question. Toothpastes containing different formulations of fluoride and bioactive glass might have the potential to prevent mineral loss on bleached enamel. However, further laboratory-based studies and controlled double-blind randomised clinical trials are required to interpret the effects of toothpastes with different fluoride and bioactive glass formulations on enamel surfaces following bleaching procedures. Keywords: bioactive glass; bleaching; enamel; remineralisation; mineral content 1. Introduction Tooth bleaching is one of the common management strategies for tooth discolouration and reported to be safe and effective when/if carried out by dentists [1]. Hydrogen peroxide is the active agent in most whitening products. This agent acts as a strong oxidising agent, Materials 2023, 16, 1368. https://doi.org/10.3390/ma16041368 https://www.mdpi.com/journal/materials