ABSTRACT
This study aimed to assess the effects of dental bleaching on the immediate shear bond strength (SBS) of composite to enamel. Different bleaching methods and time intervals between bleaching and composite restoration were examined. A total of 45 enamel specimens were divided into three groups (n = 15) based on the applied bleaching protocol: in-office (A), at-home (B), and unbleached control (C). Groups A and B were then subdivided into three time intervals until bonding: 1, 3, and 7 days. The composite was bonded to enamel using self-etch adhesive technique and submitted to SBS testing. The enamel surface and adhesive interface were observed under scanning electron microscope (SEM). The highest average SBS was measured in the control (unbleached) group (31.1 ± 3.4). A significant difference in SBS was found between the control and in-office bleaching (p < .001), as well as between control and at-home bleaching (p = .034), while the difference between in-office and at-home bleaching methods was insignificant. In relation to the waiting period, a significant reduction in SBS (p < .001) was found 1 day post-bleaching. The weakest marginal sealing to enamel under SEM was observed also 1 day after bleaching. Both bleaching methods significantly reduced the SBS of composite to enamel, especially immediately after the bleaching procedure. Reduction in SBS is temporary and 3-day waiting period seems to be sufficient to reverse the adverse effects of bleaching. RESEARCH HIGHLIGHTS: SBS of composite to enamel is significantly reduced by bleaching procedures, especially immediately after bleaching. The reduction in SBS is temporary and reversible by delaying the restoration for a minimum of 3 days.
ABSTRACT
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 self-etch 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.
ABSTRACT
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.
