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Ollie Yiru Yu,1 Ahmed Mohamed Zaeneldin,1 Hamdi Hosni Hamda Hamama,2 May Lei Mei,3 Neil Patel,4 Chun-Hung Chu1 1Faculty of Dentistry, The University of Hong Kong, Hong Kong SAR, People’s Republic of China; 2Faculty of Dentistry, Mansoura University, Mansoura, Dakahlia, Egypt; 3Faculty of Dentistry, University of Otago, Dunedin, Otago, New Zealand; 4Division of Dentistry, University of Manchester, Manchester, UKCorrespondence: Chun-Hung ChuThe University of Hong Kong, 3B26, Prince Philip Dental Hospital, 34 Hospital Road, Hong Kong SAR, People’s Republic of ChinaTel +852 2859 0287Fax +852 2559 4194Email chchu@hku.hkAbstract: The paradigms of contemporary caries management have shifted to minimal intervention dentistry. Conservative restorative procedures are recommended to replace the complete removal of all carious tissues in the management of dental caries. This article reports two clinical cases of conservative restorations of proximal caries. Different conservative cavity designs and restorative techniques were performed in the two cases. Proximal caries in posterior teeth were prepared using the box-only preparation technique or the proximal tunnel preparation technique. The cavities were restored directly with resin composites. The advantages of using the box-only preparation with fissure sealant included the maximum conservation of tooth hard tissues and the prevention of unnecessary tissue removal in the occlusal surface. The tunnel preparation preserved the marginal ridge and protected the restored tooth from fracture. The filling of composites into the tunnel demonstrated a better marginal adaptation than other restorative materials. These two techniques allowed for the preservation of more healthy dental hard tissue compared with traditional techniques. Potential problems in the restoration included the high incidence of the inappropriate removal of dental hard tissue, damage of the vital pulp and the microleakage due to the polymerization shrinkage. The solutions to minimize the risk of these problems in the operative procedures were discussed.Keywords: case report, caries, restoration, resin composite, minimally invasive dentistry

Background: The pre-cure temperature is considered an important parameter that affects the polymerization kinetics and the properties of composite restoration. As dissension exists about the effect of storing composite restorative materials in refrigerator, this study aimed to assess the effect of shelf-storage temperature on degree of conversion (DC) and microhardness of three composite restorative materials with different matrix systems., Methods: Three commercially-available composite restorative materials were used in this study; an Ormocer-based composite (Admira Fusion, Voco GmbH), a nanoceramic composite, (Ceram.X SphereTEC One, Dentsply Sirona GmbH), and a nanohybrid composite (Tetric N-Ceram, Ivoclar Vivadent AG). Regarding DC and microhardness tests, 60 disc-shaped composite specimens for each test were randomly divided into 3 groups (n = 20) according to the restorative material used. Each group was divided into 2 subgroups (n = 10) according to the composite storage temperature; stored at room temperature or stored in the refrigerator at 4°-5 °C. DC was evaluated using a Fourier-transform infrared spectrometer coupled to an attenuated total reflectance accessory. Microhardness was evaluated using micro-Vickers hardness tester under a load of 50 g with a dwell time of 10 s. The results were analyzed by ANOVA, post-hoc LSD, and independent t-tests at a significance level of p < 0.05., Results: Regarding DC test all groups showed statistically significant differences at both storage temperature. The Ormocer-based composite had the highest mean values. There was a statistically significant difference between all room-stored groups and their corresponding groups stored at refrigerator (p < 0.05). For microhardness test, all groups exhibited also statistically significant differences at both storage temperatures with the Ormocer-based composite having the highest mean values. A statistically significant difference between both room-stored and refrigerator-stored groups has been observed also (p < 0.05)., Conclusions: Refrigeration of resin-composite might have a deleterious effect on DC and microhardness of the tested composite restorative materials with different matrix systems. Moreover, the differences in the formulations of composite matrix have a potential impact on DC and microhardness., (© 2023. The Author(s).)

The aim of this study was to describe the changes in oral health policies and guidelines in response to the Coronavirus disease 2019 (COVID-19) pandemic in different countries and regions around the world. Information on oral health policies and guidelines from 9 countries (Canada, China including Hong Kong, Egypt, India, Japan, New Zealand, Nigeria, Switzerland, and Thailand) were summarized, and sources of the information were mostly the national or regional health authorities and/or dental council/associations. The changes made to the oral health guidelines depended on the severity of the COVID-19 pandemic. This included suspension of non-emergency dental care services at the peak of the COVID-19 outbreak, and easing the restrictions on non-essential and elective dental care when the pandemic became under control. The COVID-19 risk mitigation strategies include strict adherence to infection control practices (use of hand sanitizers, facemask and maintaining social distancing), reducing the amount of aerosol production in the dental setting, and managing the quality of air in the dental treatment rooms by reducing the use of air conditioners and improving air exchange. The COVID-19 pandemic has shown a major impact on dental practice. Dental professionals are trying to adapt to the new norms, while the medium to long-term impact of COVID-19 on dentistry needs further investigation., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Jiang, Duangthip, Auychai, Chiba, Folayan, Hamama, Kamnoedboon, Lyons, Matangkasombut, Mathu-Muju, Mathur, Mei, Morgan, Poolthong, Rahul, Srinivasan, Takahashi, Yaklai, Zhang, Zou, Chu and Lo.)

Objectives: The aims of this study were to conduct a systematic review of the microtensile bond strength (µTBS) of multi-mode adhesives to dentin and to perform a meta-analysis to assess the significance of differences in the µTBS of one of the most commonly used universal adhesives (Scotchbond Universal, 3M ESPE) depending on whether the etch-and-rinse or self-etch mode was used., Materials and Methods: An electronic search was performed of MEDLINE/PubMed, ScienceDirect, and EBSCOhost. Laboratory studies that evaluated the µTBS of multi-mode adhesives to dentin using either the etch-and-rinse or self-etch mode were selected. A meta-analysis was conducted of the reviewed studies to quantify the differences in the µTBS of Scotchbond Universal adhesive., Results: Only 10 studies fulfilled the inclusion criteria for the systematic review. Extensive variation was found in the restorative materials, testing methodologies, and failure mode in the reviewed articles. Furthermore, variation was also observed in the dimensions of the microtensile testing beams. The meta-analysis showed no statistically significant difference between the etch-and-rinse and self-etch modes for Scotchbond Universal adhesive ( p > 0.05)., Conclusions: Multi-mode 'universal' adhesives can achieve substantial bonding to dentin, regardless of the used modes (either etch-and-rinse or self-etch)., Competing Interests: Conflict of Interest: No potential conflict of interest relevant to this article was reported.

Objectives: The aim of this systematic review was to critically analyze previously published studies of the effects of dentin surface pretreatment with deproteinizing agents on the bonding of self-etch (SE) adhesives to dentin. Additionally, a meta-analysis was conducted to quantify the effects of the above-mentioned surface pretreatment methods on the bonding of SE adhesives to dentin., Materials and Methods: An electronic search was performed using the following databases: Scopus, PubMed and ScienceDirect. The online search was performed using the following keywords: 'dentin' or 'hypochlorous acid' or 'sodium hypochlorite' and 'self-etch adhesive.' The following categories were excluded during the assessment process: non-English articles, randomized clinical trials, case reports, animal studies, and review articles. The reviewed studies were subjected to meta-analysis to quantify the effect of the application time and concentration of sodium hypochlorite (NaOCl) and hypochlorous acid (HOCl) deproteinizing agents on bonding to dentin., Results: Only 9 laboratory studies fit the inclusion criteria of this systematic review. The results of the meta-analysis revealed that the pooled average microtensile bond strength values to dentin pre-treated with deproteinizing agents (15.71 MPa) was significantly lower than those of the non-treated control group (20.94 MPa)., Conclusions: In light of the currently available scientific evidence, dentin surface pretreatment with deproteinizing agents does not enhance the bonding of SE adhesives to dentin. The HOCl deproteinizing agent exhibited minimal adverse effects on bonding to dentin in comparison with NaOCl solutions., Competing Interests: Conflict of Interest: No potential conflict of interest was reported by the authors.