SARS-CoV-2 is a member of the family of coronaviruses. The first cases were recorded in Wuhan, China, between December 2019 and January 2020. Italy is one of the most affected countries in Europe. COVID-19 is a new challenge in modern dentistry. New guidelines are required in dental clinics to avoid contagion caused by cross-infections. A narrative review was performed using both primary sources, such as scientific articles and secondary ones, such as bibliographic indexes, web pages, and databases. The main search engines were PubMed, SciELO, and Google Scholar. Twelve articles were selected to develop the bibliographic review by applying pre-established inclusion and exclusion criteria. Precautionary measures should be applied to control COVID-19 in clinical practice. Several authors have highlighted the importance of telephone triage and/or clinic questionnaires, body temperature measurement, usage of personal protective equipment, surface disinfection with ethanol between 62% and 71%, high-speed instruments equipped with an anti-retraction system, four-handed work, and large-volume cannulas for aspiration. Clinically, the use of a rubber dam is essential. FFP2 (or N95) and FFP3 respirators, if compared to surgical masks, provide greater protection for health workers against viral respiratory infections. Further accurate studies are needed to confirm this.

Aim of this investigation is to evaluate prevalence, localization, and height of 114 maxillary sinus septa by using cone-beam computed tomography scans. The thickness of the mucosa has been measured together with the variations of the membrane in relation to those septa. A total of 228 maxillary sinuses have been considered. Septa were identified using "panorex" reconstructions and axial scans of cone-beam computed tomography using the software "eXamVision." The thickness of the mucosa has been evaluated in the paraxial scans and related to those septa where they were present. In the current study, the prevalence of sinus septa is 38.1%. Significant difference can be found in the height of primary and secondary septa. The mean height of primary septa was 5.5 mm (± 1.19) and of secondary septa 3.4 mm (± 1.6). Anterior and medium septa resulted significantly higher than posterior septa (P = 0.003). The medium thickness of the mucosa was 0.85 mm (± 0.58), whereas close to the septa it turned out to be 1.8 mm (± 1.87). The difference is statistically relevant (P = 0.003). There is no statistically significant proportional relation between dimensions of septa and thickness of mucosa (P = 0.53). Underwood septa are frequent anatomic variations of the maxillary sinus. Their presence may result in a thickening of the sinus membrane. The systematic study of radiographic anatomy of maxillary sinus is necessary before the sinus lift surgery planning.

KEYWORDSMicrotensile bond strength; Adhesion; Self-etching; All-in-one adhesives; Failure mode; Technique sensitivity Summary Purpose: To evaluate the technique sensitivity of four different adhesive systems using different air-blowing pressure. . Twenty-four extracted molars were used. After grinding the coronal enamel surface, the teeth were divided into two equal groups. The first group's teeth were randomly assigned for bonding with the different adhesives using gentle air-blowing (g). For the teeth of the second group, the four adhesive systems were applied using strong air-blowing (s). After storage overnight in 37 8C water, the bonded specimens were sectioned into sticks (1 mm! 1 mm wide), which were subjected to microtensile bond strength testing (mTBS) at a crosshead speed of 1 mm/min. The load at failure of each specimen was recorded and the data were analyzed by one-way ANOVA and Tukey HSD tests. The surfaces of the fractured specimens were observed using SEM to determine the failure mode. Results: The results of the mTBS test showed that the highest bond strengths tended to be with SE for both gentle and strong air-blowing, and the significantly lowest for SSB with strong air streaming. Comparing the two techniques, significant differences were noted only for SSB-200 (P!0.05). For each material, the SEM evaluation did not show distinct differences in the nature of the fractures between the two techniques, except for SSB-200. Conclusions: The adhesives tested are not technique sensitive, except SSB-200, with regards to the air-blowing step. Q

SUMMARYThis study compared the microtensile bond strength (MTBS) of three all-in-one adhesive systems and a two-step system using two types of burs to prepare the dentin surfaces. Flat coronal surfaces of 24 extracted human molars were produced using either regular-grit or superfine-grit diamond burs. Resin composite was then bonded to equal numbers of these surfaces using one of the four adhesives: Clearfil SE Bond (CSE), GBond (GB), SSB-200 (SSB) or Prompt L-Pop (PLP). After storage for 24 hours in 37°C distilled water, the bonded teeth were sectioned into slices (0.7-mm thick) perpendicular to the bonded surface. The specimens were then subjected to microtensile testing and the bond strengths were calculated at failure. Bond strength data were analyzed by two-way ANOVA and the GamesHowell test for interaction between adhesive and type of cut dentin. The fractured surfaces were observed by SEM to determine the failure mode. In addition, to observe the effect of conditioning, equal numbers of the two bur-cut dentin surfaces of eight additional teeth were conditioned with the adhesives and observed by SEM. Based on the results, when CSE and SSB were bonded to dentin cut with a regular-grit diamond bur, the MTBS values were significantly lower than that of superfine bur-cut dentin; whereas, GB and PLP showed no significant differences in MTBS between the two differently cut surfaces. SEM observation of the fractured surfaces revealed a mixed mode (adhesive in some areas and cohesive in others in the same sample) of failure in all specimens except PLP, which showed cohesive failure within the adhesive for both types of bur In some self-etching systems, selecting the proper bur type for cutting dentin is important for improving bond strength. Laboratory Research 318Operative Dentistry preparation. Generally, SEMs of the conditioned surfaces using both types of burs showed partial removal of the smear layer for CSE, minimal for GB and SSB and complete removal for PLP.In conclusion, when cutting dentin, selecting the proper bur type is important for improving the bond strength of some self-etching adhesive systems.