Marginal accuracy of provisional crowns using three material systems and two techniques: A scanning electron microscope study.

OBJECTIVE: The most important desideratum of a provisional crown is an adequate marginal fit that is essential for maintaining optimal periodontal health, reducing the sensitivity of freshly prepared dentin and protection of the pulp. The purpose of this in vitro study was to compare the vertical marginal accuracy of provisional crown materials using three different material systems (chemically activated PMMA powder-liquid system, light activated UDMA single paste system, and chemically activated Bis-GMA two paste auto mix system) and two different techniques (direct and indirect). METHODS: Two customized stainless steel dies, simulating prepared and unprepared tooth were used to fabricate 40 provisional crowns. Additional silicone elastomeric impression and a vacuum-formed polypropylene sheet were used as a matrix. Ten crowns, each of the three material systems used in the study (n = 10 × 3) were fabricated using the direct technique and ten crowns from chemically activated PMMA powder-liquid system (n = 10 × 1) using an indirect technique. Scanning electron microscope (SEM) was used to measure vertical marginal discrepancies at x100 magnification. The results were analyzed using descriptive statistics and comparisons between various groups were made using one way analysis of variance (ANOVA) after checking the normality of data using Shapiro Wilk's Test. Post Hoc Tukey HSD Test was used to determine the statistical difference between the means of independent group pairs. RESULTS: The mean marginal discrepancies of Bis-GMA composite resin, UDMA composite resin, and PMMA acrylic resin using direct technique were 67.15 µm, 71.01 µm, and 84.56 µm respectively. PMMA acrylic resin showed a mean marginal discrepancy of 103.03 µm using the indirect technique. CONCLUSION: This study has shown that provisional crowns fabricated with Bis-GMA composite resin material (two paste auto mix system) registered the best marginal accuracy. Provisional crowns fabricated with indirect technique recorded less marginal opening than with direct technique.

Comparative in-vitro microscopic evaluation of vertical marginal discrepancy, microhardness, and surface roughness of nickel-chromium in new and recast alloy.

Reusing of alloy has become a need of time due to the increasing demand, depletion of resources, and substantial increase in their price. The alloys used require a long-term stay in the oral cavity exposed to a wet environment, so they must have good wear resistance, biocompatibility, and mechanically good strength. In this study, the vertical marginal discrepancy, surface roughness, and microhardness of the new and recast nickel-chromium (base metal) alloys were evaluated. 125 wax patterns were fabricated from a customized stainless steel master die with a heavy chamfer cervical margin divided into 5 groups. Each group had 25 samples. Group A: 25 wax patterns were cast using 100% by weight of new alloy, Group B: the casting was done by using 75% new alloy and 25% alloy by weight, Group C: wax patterns were cast using 50% new alloy and 50% alloy, Group D: 25% new alloy and 75% alloy and Group E: 100% recast alloy. The vertical marginal discrepancy was measured by an analytical scanning microscope, microhardness was tested on a universal testing machine, and surface roughness was on a tester of surface roughness. Castings produced using new alloys were better than those obtained with reused alloys. Alloys can be reused till 50% by weight along with the new alloy and accelerated casting technique can be used to save the lab time to fabricate castings with acceptable vertical marginal discrepancy, microhardness, and surface roughness. This indicated that 50% recasting of (Ni-Cr) can be used as a good alternative for the new alloy from an economical point of view.

Perception, attitude, and preference of trainees towards workplace-based assessment in dental education at a tertiary care institute in Multan, Pakistan.

BACKGROUND: Modern medical education has flourished with an emergent interest in a variety of assessment approaches that entails direct observation of performance and provision of feedback. Workplace-based assessment (WPBA) has been embraced into specialty training in the United Kingdom (UK) within National Health Service (NHS). In Pakistan, this educational framework is incorporated to gauge the clinical proficiency of trainees at the postgraduate and undergraduate levels. The present study was done to identify how WPBA is perceived by dental field postgraduate trainees in Pakistan. OBJECTIVE: The study explored and ascertained trainees' perceptions, attitudes, and preferences considering their experiences with the systematic organization and execution of WPBA in dental educational settings. METHODS: This cross-sectional study design involved the clinical trainees of various cadres in a tertiary care hospital in Multan. A structured and validated questionnaire previously used for another analysis was administered among 90 trainees at the institute. The results were analyzed and tabulated using SPSS-21. Influential statistics (Pearson's Chi-Square Test) was performed and the confidence interval was set at 95% (P≤0.05). RESULTS: The response rate was 88%. Opinions were more positive compared to the former surveys. The majority of the respondents (65.8%) have shown a positive attitude towards WPBA and preferred it to be a valuable assessment system as it fosters reflective practices in educational settings. In addition, it was shown that WPBA has the potential to improve clinical training (72.2%) and aid in the effective implementation of clinical practice (68.4%). As the system of digital education has been introduced ever since the pandemic, the highest percentage of participants (56%) preferred a combination of on-paper and online assessment systems. CONCLUSION: The study reported that WPBA proposes the opportunity to associate teaching, learning, and assessment. The faculty training program is a significant input to upholding the quality of WPBA. Empirical research on WPBA is essential to be carried out to overcome the inadequacies thus endorsing its application universally.

Provision of Endodontic Treatment in Dentistry amid COVID-19: A Systematic Review and Clinical Recommendations.

BACKGROUND: The risk of acquiring COVID-19 during a pandemic is a major concern among health care workers. Dental professionals being in close proximity to the patients had been exposed more than other health care workers. Hence, all the standard operating procedures (SOPs) are strictly advised to be followed. METHODS: A detailed relevant literature search was conducted in international databases such as PubMed, Web of Science, and Science Direct, from January 2020 to November 2020. All the studies that provided recommendations regarding endodontic procedures during the COVID-19 pandemic were included, and those that were not in the English language, case reports, book chapters, and short communications were excluded in this review. In the end, only 6 articles were selected for the systematic review considering that complete information regarding the provision of dental care in the time of COVID-19 with diagnostic accuracy (STARD) was provided. RESULTS: Endodontic treatments were restricted to only emergency dental procedures, and all other patients have advised medications and catered through teledentistry. Endodontic emergencies were advised to be carried out with minimal aerosol production procedures. CONCLUSION: Provision of endodontic care during COVID-19 restricted to only emergency dental procedures by strictly following standard operating procedures. A protocol for COVID-19 prevention was followed by all the dentists and the dental staff in the dental clinics.

Influence of time, temperature and humidity on the accuracy of alginate impressions.

BACKGROUND: The goal of the current in vitro study was to assess the dimensional accuracy of dental impressions when stored at different times, temperature and humidity. METHODS: Impressions were poured to an aluminium triangular die and three teeth placed at the three corners of the die. A total of 130 impressions were made, in which 10 were poured immediately following manufacturers' instructions and the remaining 120 specimens were divided into two groups on the basis of relative humidity during storage. Group-1: 100%, Group-2: 50% relative humidity. Impression was poured with type IV gypsum. The below points were chosen to determine the length between in each of the specimens using the traveling microscope with 10x magnifications after 24 hours of model recovery for calculating the effect of changes in storage conditions- relative humidity, temperature and delay in pouring the impressions, on dimensional accuracy. RESULTS: Analysis of the results revealed that the casts achieved by pouring alginate impressions without delay were most accurate than the delay pouring. With the increase in temperature and time, the distance between the points increased and the casts obtained were bigger. CONCLUSION: Irreversible hydrocolloids should be poured immediately for optimum dimensional stability.