Endocrown restorations in premolars: influence of remaining axial walls of tooth structure and restorative materials on fatigue resistance.

OBJECTIVES: To evaluate the effect of the remaining tooth structure and different CAD/CAM materials on the fatigue performance and failure mode of endodontically treated premolars restored with endocrowns. MATERIALS AND METHODS: Ninety maxillary premolars were endodontically treated and assigned into 6 groups (n = 15) according to the number of remaining axial walls (four, three, and two) and restorative materials (ultra-translucent zirconia 5Y-PSZ [KATANA UTML] and lithium disilicate [IPS e.max-CAD]). The specimens were subjected to cyclic fatigue loading test (initial load 200 N; 20 Hz). An incremental step load of 100 N per 10,000 cycles was applied until failure. The fatigue failure load (FFL) and number of failure cycles (CFFs) data were statistically analyzed with two-way ANOVA and Kaplan-Meier test (α = 0.05). Failed specimens were examined under a stereomicroscope 25 × and failure modes were determined. RESULTS: FFL and CFF were significantly influenced by restorative material (p < 0.05). 5Y-PSZ endocrowns showed significantly higher FFL when compared with lithium disilicate. The number of remaining walls did not affect the fatigue behavior or failure mode of the specimens. Of the lithium disilicate restorations, 51% had repairable failures, while 95% 5Y-PSZ restorations had non-repairable failures. CONCLUSIONS: Zirconia endocrowns showed better FFL than lithium disilicate endocrowns, regardless of the number of remaining axis walls. Lithium disilicate and 5Y-PSZ endocrowns showed FFL higher than the normal masticatory loads. CLINICAL RELEVANCE: Restoring endodontically treated premolars with endocrown could be a promising treatment, regardless of the remaining axial walls. However, precaution should be taken in material selection since it affects the fatigue resistance and failure mode.

Mouth shield to minimize airborne transmission risk of COVID-19 and other infectious diseases in the dental office.

Transmission of coronavirus disease (COVID-19) and other infectious diseases is a significant risk during dental procedures because most dental interventions involve aerosols or droplets that could contaminate the surrounding environment. Current protection guidelines to address the high risk of droplets, aerosols, and airborne particle transmission of COVID-19 in the dental office recommend minimizing aerosol-generating procedures. In this paper, an innovative mouth shield is presented that should minimize water backsplash from the air-water syringe during dental treatment. The mouth shield can be added to the personal protective equipment to provide the dental team with extra protection. It can be made of different materials, is straightforward, inexpensive, and safe to fabricate, and is easy to use.

Determinants of COVID-19 Vaccine Acceptance among Dental Professionals: A Multi-Country Survey.

PURPOSE: This study sought to investigate the acceptance rate and associated factors of COVID-19 vaccines among dentists and dental students in seven countries. MATERIAL AND METHODS: A structured questionnaire prepared and guided by the report of the SAGE Working Group on Vaccine Hesitancy was distributed among groups of dentists and dental students in seven countries across four continents. RESULTS: A total of 1527 subjects (850 dentists and 677 dental students) participated in this survey. Although 72.5% of the respondents reported their intention to accept COVID-19 vaccines (dentists: 74.4%, dental students: 70.2%), there was a significant difference in agreement between dentists/dental students across countries; generally, respondents in upper-middle-, and high-income countries (UM-HICs) showed significantly higher acceptance rates compared to those in low- and lower-middle income countries (L-LMICs). Potential predictors of higher vaccine acceptance included being a dentist, being free of comorbidity, being well-informed about COVID-19 vaccines, having better knowledge about COVID-19 complications, having anxiety about COVID-19 infection, having no concerns about the side effects of the produced vaccines and being a resident of an UM-HIC. CONCLUSION: The results of our survey indicate a relatively good acceptance rate of COVID-19 among the surveyed dentists and dental students. However, dentists and dental students in L-LMICs showed significantly lower vaccine acceptance rates and trust in COVID-19 vaccines compared to their counterparts in UM-HICs. Our results provide important information to policymakers, highlighting the need for implementation of country-specific vaccine promotion strategies, with special focus on L-LMICs.

A Global Survey of COVID-19 Vaccine Acceptance Among Healthcare Workers.

Objectives: Even though several effective vaccines are available to combat the COVID-19 pandemic, wide disparities in vaccine distribution, and vaccine acceptance rates between high- and low-income countries appear to be major threats toward achieving population immunity. Our global descriptive study aims to inform policymakers on factors affecting COVID-19 vaccine acceptance among healthcare workers (HCWs) in 12 countries, based on income index. We also looked for possible predictors of vaccine acceptance among the study sample. Methods: A structured questionnaire prepared after consultation with experts in the field and guided by the "Report of the SAGE working group on vaccine hesitancy" was administered among 2,953 HCWs. Upon obtaining informed consent, apart from demographic information, we collected information on trust in vaccines and health authorities, and agreement to accept a COVID-19 vaccine. Results: Although 69% of the participants agreed to accept a vaccine, there was high heterogeneity in agreement between HCWs in low and lower-middle income countries (L-LMICs) and upper-middle- and high-income countries (UM-HICs), with acceptance rates of 62 and 75%, respectively. Potential predictors of vaccine acceptance included being male, 50 years of age or older, resident of an UM-HIC, updating self about COVID-19 vaccines, greater disease severity perception, greater anxiety of contracting COVID-19 and concern about side effects of vaccines. Conclusions: COVID-19 vaccine acceptance among HCWs in L-LMICs was considerably low as compared to those from UM-HICs. The lowest vaccine acceptance rates were among HCWs from the African continent. This underlines the need for the implementation of country-specific vaccine promotion strategies, with special focus on increasing vaccine supply in L-LMICs.

Fracture resistance of teeth restored with endocrowns: An in vitro study.

OBJECTIVE: The objective of this study is to evaluate the fracture resistance and failure mode of endodontically treated teeth restored with lithium disilicate endocrowns of different crown thicknesses. MATERIALS AND METHODS: A total of 30 endodontically treated permanent mandibular first molars were sectioned horizontally 2 mm above the highest point of the cemento-enamel junction. The specimens were divided into three groups, and each group was restored with lithium disilicate (IPS e-max press) endocrowns of different crown thicknesses (3, 4.5, and 6 mm, respectively). After cementation, specimens were stored in room temperature for 72 hours, followed by subjecting them to compressive strength testing until failure. The fracture loads and the failure mode were recorded. Statistically analysis was performed using one-way analysis of variance. RESULTS: A statistically significant difference was found in the fracture resistance between the three groups with the highest fracture resistance in the 3 mm group, followed by the 4.5 mm group, and the least in the 6 mm group (P < .05). Most of the failures were accompanied with tooth fracture (90% in 3 mm group, 100% in 4.5 mm group, and 80% in 6 mm group). CONCLUSIONS: Increasing the crown thickness of the endocrowns reduced the fracture resistance of restored teeth. Minimum fracture loads for all teeth restored with endocrowns were significantly higher than the maximum occlusal forces reported in the literature. CLINICAL SIGNIFICANCE: Fracture resistance and mode of failure of lithium disilicate (IPS e-max press) endocrowns varies widely between crown thicknesses. Clinicians should be cautious with crown thickness for endocrown restorations.

Survey of Dental Materials Used by Dentists for Indirect Restorations in Saudi Arabia.

The purpose of this study was to investigate the use and selection of materials for indirect restorations by dentists in Saudi Arabia. A structured 18-item questionnaire was designed and sent via email to all dentists with active memberships in the Saudi Dental Society. A total of 373 dentists (20.2%) out of the 1,846 contacted answered the questionnaire. The majority of the responding dentists (81.5%) prefer to use porcelain-fused-to-metal crowns for posterior teeth, while 77.5% use all-ceramic crowns for anterior teeth. Only 29.8% reported using computer-aided design/computer-assisted manufacture in their practice. There was inconsistency among dentists in material selection, and this was affected by the dentist's gender, years of experience, specialty, and service sector.