Aim
The level of preparedness of the healthcare system plays an important role in management of coronavirus disease 2019 (COVID‐19). This study attempted to devise a comprehensive protocol regarding dental care during the COVID‐19 outbreak.
Methods and result
Embase, PubMed, and Google Scholar were searched until March 2020 for relevant papers. Sixteen English papers were enrolled to answer questions about procedures that are allowed to perform during the COVID‐19 outbreak, patients who are in priority to receive dental care services, the conditions and necessities for patient admission, waiting room and operatory room, and personal protective equipment (PPE) that is necessary for dental clinicians and the office staff.
Conclusion
Dental treatment should be limited to patients with urgent or emergency situation. By screening questionnaires for COVID‐19, patients are divided into three groups of (a) apparently healthy, (b) suspected for COVID‐19, and (c) confirmed for COVID‐19. Separate waiting and operating rooms should be assigned to each group of patients to minimize the risk of disease transmission. All groups should be treated with the same protective measures with regard to PPE for the dental clinicians and staff.
Purpose
To assess the effect of tooth preparation design on fracture resistance of zirconia‐reinforced lithium silicate overlays.
Materials and Methods
This study evaluated 50 human maxillary first molars with no caries, restorations or anatomical defects. The teeth were randomly divided into five groups (n = 10/group) based on preparation design for the fabrication of overlay restorations: (O) anatomical occlusal reduction, (OS) anatomical occlusal reduction with round shoulder preparation, (OG) anatomical occlusal reduction with a central groove, (OSG) anatomical occlusal reduction with round shoulder preparation and central groove, and (C) no preparation of tooth (control group). All restorations were fabricated using zirconia‐reinforced lithium silicate (Vita Suprinity). The specimens underwent thermomechanical fatigue loading in a masticatory simulator (1.2 million cycles at 98 N). Fracture resistance was measured using a universal testing machine. The mode of failure was determined as well. Data were analyzed using one‐way ANOVA followed by Tukey's post‐hoc test, paired t‐test and Fisher's exact test (α = 0.05).
Results
Group O showed significantly higher fracture resistance than groups OG and OSG (p = 0.002 and p = 0.001, respectively). The fracture resistance of group OS was significantly higher than that of group OSG (p = 0.008). The fracture resistance of the control group was significantly higher than that of OG and OSG (p = 0.001) and had no significant difference with other groups.
Conclusions
Group O (anatomical occlusal reduction alone), which had the most conservative preparation design, yielded the highest fracture resistance.
Introduction:To investigate the galvanic corrosion of brackets manufactured by four different companies coupled with stainless steel (SS) or nickel-titanium (NiTi) wires in an artificial saliva solution.
Materials and methods:A total of 24 mandibular central incisor Roth brackets of four different manufacturers (American Orthodontics, Dentaurum, Shinye, ORJ) were used in this experimental study. These brackets were immersed in artificial saliva along with SS or NiTi orthodontic wires (0.016″, round) for 28 days. The electric potential difference of each bracket/ wire coupled with a saturated calomel reference electrode was measured via a voltmeter and recorded constantly. Corrosion rate (CR) was calculated, and release of ions was measured with an atomic absorption spectrometer. Stereomicroscope was used to evaluate all samples. Then, samples with corrosion were further assessed by scanning electron microscope and energydispersive X-ray spectroscopy. Two-way analysis of variance was used to analyze data.Results: Among ions evaluated, release of nickel ions from Shinye brackets was significantly higher than that of other brackets. The mean potential difference was significantly lower in specimens containing a couple of Shinye brackets and SS wire compared with other specimens. No significant difference was observed in the mean CR of various groups (p > 0.05). Microscopic evaluation showed corrosion in two samples only: Shinye bracket coupled with SS wire and American Orthodontics bracket coupled with NiTi wire.
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