The recent spread of COVID-19 presents a huge public health concern. Clinical presentations of COVID-19 range from asymptomatic cases to severe pneumonia that can lead to death. Drastic measures were necessary to prevent the disease from spreading and protect the most vulnerable groups in the general population. The rapid reorganization of the healthcare system and great efforts made by medical staff were needed to admit to hospitals and then treat a progressively growing number of patients. The predominant route of virus transmission is through direct contact with an infected individual or respiratory droplets, therefore, all dental procedures with aerosol-formation pose an extremely high risk for the spread of infection. The aim of this article is to provide an overview of the current epidemiological situation, routes of transmission, and specific recommendations for dental practices including patient screening and triage, infection control, and treatment protocols. In this situation, it is essential that all dental healthcare workers make wise clinical decisions and educate themselves and their patients on how to prevent the spread of infection.

Adhesive bond strength at the composite/dentin interface is influenced by various factors, including the etching mode and composite resin type. The purpose of this study was to evaluate the influence of the total-etch and self-etch mode on the microtensile bond strength (μTBS) of conventional and bulk-fill composite to dentin, using the universal adhesive system. Sixty non-carious human teeth were sectioned parallel to their longitudinal axis, using a low-speed diamond saw to obtain a flat dentin surface.According to the etching technique and composite resin type used, teeth were randomly divided into four different groups (n = 15): TC (total-etch/conventional composite), TB (total-etch/bulk-fill composite), SC (self-etch/conventional composite), and SB (self-etch/bulk-fill composite). Cylindric composite build-ups were made with 3M Filtek Z250 and 3M Filtek Bulkfill Posterior, using a plastic mold, 4 mm in diameter and 4 mm in height. The specimens were subjected to the μTBS test in a universal testing machine and failure force was recorded. Failure modes were determined using stereoscopic and scanning electron microscopy. Data were analyzed using the two-way ANOVA and Student's t test. The μTBS was significantly affected by the etching technique. A significant statistical difference was determined between total-etch and selfetch groups, irrespective of the composite resin type used. Higher bond strength was obtained in total-etch groups. The μTBS was not affected by the composite resin type.No significant statistical difference was determined between the conventional and bulk-fill groups, irrespective of the etching-mode.

This study aimed to examine the effects of different light-curing modes on the immediate shear bond strength (SBS) of different composite resin types to dentin using universal adhesive. Human teeth were extracted and sectioned to obtain flat dentin slices. The universal adhesive was applied in total-etch mode. Conventional and bulkfill composites were used to create cylindric build-ups. Full power and Ramp mode were used to light-cure the adhesive and composite resin. SBS test was performed in a universal testing machine, and failure modes were determined via scanning electron microscopy (SEM). Two-way ANOVA and Student t-test were used to analyze statistical data. Significantly higher SBS was obtained when bulkfill composite was used compared to the conventional one ( p < .001). The difference between Full power and Ramp curing mode was insignificant ( p = .4). Mixed failure was the predominant type. Low SBS resulted in adhesive failure, while high SBS resulted in cohesive failure. Shear bond strength was not curing-dependent but rather material-dependent. Ramped curing does not contribute to higher bond strength. Bulkfill composite seems to be more favourable in terms of bond strength.

Composite materials used for the restoration of lost dental tissues fulfill almost all functional and aesthetic requirements. However, polymerization shrinkage still remains the main problem of light-curing composite resins. The consequences of this phenomenon are microfractures and microleakage in the marginal areas of the composite restoration.The aim of this paper is to present the most important methods for reducing polymerization shrinkage of adhesive restorations, based on the contemporary literature available. These methods include changes in the chemical composition of the composite, correct application technique of the adhesive-composite system and selection of the appropriate light curing protocol.In the last few years, composite materials have experienced significant changes in the chemical composition in order to compensate for their major shortcomings. By introducing pre-polymerized filler particles, alternative matrices based on silorane and ormocer, and new germanium-based photoinitiators, the degree of polymerization shrinkage has been significantly reduced.Optimal adhesive bond between the filling and the tooth can compensate volumetric shrinkage of material which occurs during polymerization. Numerous studies have shown that total-etch adhesive systems, in comparison with self-etch, form a better adhesive bond to hard dental tissues. Polymerization shrinkage can also be reduced and marginal adaptation improved by applying a stress-absorbing layer and preheated composite.With the use of modified light-curing protocols, such as soft start with reduced initial light intensity, and pulse-delayed with relaxation period, the negative effects of polymerization shrinkage and stress development can be further reduced, and the risk of microfracture formation minimized. 2019; 36(4):334-342 335 4 Odeljenje za stomatološku protetiku, Klinika za stomatologiju, Niš, Srbija 5 Univerzitet u Kragujevcu, Fakultet medicinskih nauka, Departman za stomatologiju, Kragujevac, Srbija Acta facultatis medicae NaissensisSAŽETAK Kompozitni materijali koji se danas koriste za restauraciju izgubljenih zubnih tkiva, ispunjavaju skoro sve funkcionalne i estetske zahteve. Međutim, glavni problem svetlosnopolimerizujućih kompozita i dalje ostaje pojava kontrakcije prilikom polimerizacije. Posledice ovog fenomena su nastanak mikropukotine i mikrocurenja u predelu marginalnog spoja. Cilj ovog rada je da na osnovu savremene dostupne literature, predstavi najznačajnije metode za smanjenje kontrakcije adhezivnih restauracija. To su: promena hemijskog sastava kompozita, pravilna tehnika aplikovanja adhezivno-kompozitnog sistema i izbor odgovarajućeg režima svetlosne polimerizacije. Kompozitni materijali su zadnjih godina doživeli najviše promena u pogledu hemijskog sastava, sa ciljem kompenzovanja njihovih glavnih nedostataka. Uvođenjem prepolimerizovanih čestica punioca, alternativnih matriksa na bazi silorana i ormocera, i novih fotoinicijatora na bazi germanijuma, u značajnoj meri je redukovan stepen polimerizacione kontrakcije. Kva...

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