Influence of spark plasma sintering and baghdadite powder on mechanical properties of hydroxyapatite

AbstractSince hydroxyapatite-based materials have similar composition and crystallinity as natural calcified tissues, can be used for bone/tissue engineering. In the present study a novel nanocomposite based on bioceramics such as Natural Hydroxyapatite (NHA) and Baghdadite (BAG), was sintered by spark plasma sintering (SPS) technique. The prepared composite was characterized using scanning electron microscopy (SEM), X-ray diffractometer (XRD) and Brunauer–Emmett–Teller (BET) techniques. The porosity of the samples was measured by Archimedes method. The cold crushing strength (CCS) test was applied to evaluate their mechanical properties. Our results demonstrated that NHA-30wt. %BAG nanocomposite specimens have the lower CCS in comparison with other examined composites. Consequently, NHA/BAG samples exhibited acceptable mechanical properties and could be suitable candidates for bone tissue engineering applications especially orthopaedic fields

A Comparative Study of Cervical Composite Restorations Microleakage Using Dental Universal Bonding and Two-step Self-etch Adhesive

© 2021. The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Aim: The aim of this study is to compare microleakage of cervical restorations using universal bonding and two-step self-etch adhesive with or without enamel etching through a dye penetration testing method. Materials and methods: In this in vitro experimental study, 70 maxillary premolar teeth with no anomaly or decay were randomly divided into five groups of 14. Conventional cervical cavities were prepared with diamond bur on the facial surface of the teeth. The teeth were prepared using G-Premio Bond/self-etch technique, G-Premio Bond/total-etch technique, G-Premio Bond/selective-etch technique, Clearfil SE Bond/ self-etch technique, and Clearfil SE Bond/selective-etch technique in Groups I to V, respectively, and restored with composite. Microleakage at the occlusal enamel margin and the cervical dentinal margin was ranked from 0 to 4 based on dye penetration using stereomicroscope (×32). Statistical analysis was carried out using Kruskal-Wallis and Mann-Whitney tests at a significance level of α = 0.05. Results: The mean occlusal microleakage in the five study groups was 1.07, 0.57, 0.57, 1.28, and 0.78, respectively. The mean cervical microleakage was 0.97, 0.85, 0.64, 1.35, and 1.14, respectively. Kruskal-Wallis test showed significant difference between the microleakage scores of different groups in enamel (p = 0.022) and dentin (p = 0.01). Clearfil SE Bond/self-etch technique group showed the highest mean score of microleakage in enamel margins, and G-Premio Bond/total-etch technique and G-Premio Bond/selective-etch technique groups showed lowest enamel microleakage mean. Clearfil SE Bond/self-etch group showed the highest mean score of microleakage in dentin margins, while G-Premio Bond/ selective-etch technique group showed the lowest mean score of dentin microleakage. Conclusion: Selective etching of enamel will decrease enamel microleakage. G-Premio Bond shows better microleakage results in comparison to Clearfil SE Bond in dentinal margins. Clinical significance: A major problem in cervical composite restorations is the presence of microleakage in the cervical wall. Different adhesive systems have been designed to overcome this problem