Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Synthesis and characterization of bioactive glass fiber-based dental restorative composite Mariam Raza Syed f,1 , Nida Zehra Bano b,1 , Sarah Ghafoor a , Hina Khalid c , Shahreen Zahid b , Usama Siddiqui f , Abbas Saeed Hakeem d , Anila Asif c , Muhammad Kaleem b , Abdul Samad Khan e,* a Department of Oral Biology, University of Health Sciences, Lahore, 54000, Pakistan b Department of Dental Materials, Army Medical College, National University of Medical Sciences, Rawalpindi, 46000, Pakistan c Interdisciplinary Research Centre in Biomedical Materials, COMSATS University Islamabad, Lahore Campus, Lahore, 54000, Pakistan d Center of Excellence in Nanotechnology, King Fahd University of Petroleum & Minerals, Dhahran, 31261, Saudi Arabia e Department of Restorative Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, 31441, Saudi Arabia f Department of Dental Materials, University of Health Sciences, Lahore, 54000, Pakistan ARTICLE INFO Keywords: Nano-hydroxyapatite E-glass fiber Resin-based composites Tooth interface Bond strength Micro-hardness ABSTRACT This study focused on the synthesis and characterizations of a newly developed bioactive glass fiber-based (nano- hydroxyapatite/E-glass fiber) dental composite. The nano-hydroxyapatite grafted E-glass (nHA/E-glass) bioac- tive fibers were synthesized using the microwave irradiation technique. The experimental composites were prepared by incorporating 0, 40, 50, and 60 wt% of nHA/E-glass fiber in resin matrices. The structural, mor- phological, thermal, and mechanical properties were assessed. The in vitro bond strength test was performed at days 1, 30, 90, and 180. Whereby, water sorption analysis in deionized water was performed at days 1, 7, 21, and 40. All experimental composite groups showed the homogenous distribution of reinforcing agents, and a sig- nificant difference in the degree of conversion among all groups was observed. It was observed that with the increase in the concentration of reinforcing agents, the intensity of spectral phosphate peaks also increased. The higher the nHA/E-glass fibers content, the higher the glass transition temperature, micro-hardness, and flexural modulus. Contrarily, flexural strength decreased with increased filler concentration. Water sorption was higher in unfilled composites compared to the composites with a high concentration of nHA/E-glass fibers. For each composite, there was no statistical significance (p ≥ 0.05) in bond strength from 1 to 90 days, whereas, at day 180, composites with 50 wt% and 60 wt% nHA/E-glass showed statistically significant difference (p ≤ 0.05) than other composite groups. This newly developed composite showed promising results with comparable structural, physical, and mechanical properties. 1. Introduction New techniques in dental sciences have brought a revolutionary change in conventional treatment methods. The advancement in direct restorative materials occurred with the synthesis of new polymeric systems and the introduction of inorganic fillers. Filler modifications such as surface treatment, grafting, and inclusion of antibacterial agents have been considered effective approaches to increasing the longevity of composite materials [1,2]. With the advent of nanotechnology, a variety of nano-materials has shown favorable results as compared to traditional fillers in terms of physical and mechanical properties [3,4]. Over the period, bioceramic fillers have become the vital and in- tegral components of modern dentistry [5]. Among them, second generation bioceramic materials (amorphous calcium phosphate, tri- calcium phosphate, bioactive glass, hydroxyapatite, etc.) have gained interest to be used as reinforcing agents in adhesives and resin-based composites (RBC) [6,7]. However, issues remain with the low me- chanical properties associated with calcium phosphate-based dental restorative materials [8]. Therefore, it is still not clear, which bio- ceramic material should be incorporated in dental resins to fulfill the requirements of restorative materials relevant to the oral environment. In the previous decade, reinforced glass fiber composites have gained much more attraction in dentistry [9–11]. In 2013, short fi- ber‐reinforced composite (SFRC) (everX Posterior™; GC, Tokyo, Japan) was introduced with the goal of mimicking the stress-absorbing prop- erties of dentin. However, it is still questionable whether this SFRC https://doi.org/10.1016/j.ceramint.2020.05.268 Received 28 January 2020; Received in revised form 6 May 2020; Accepted 25 May 2020 * Corresponding author. E-mail address: akhan@iau.edu.sa (A.S. Khan). 1 both authors consider as first author. Ceramics International xxx (xxxx) xxx–xxx 0272-8842/ © 2020 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Mariam Raza Syed, et al., Ceramics International, https://doi.org/10.1016/j.ceramint.2020.05.268