The Effect of Brand, Thickness, and Abutment Substrate on the Masking Ability of Monolithic Zirconia Cera The goal of the present study was to determine the minimum thickness of monolithic zirconia required to achieve an acceptable masking ability and to examine how brand, thickness, and abutment substrate influenced that masking ability (∆E). Seventy-two A2-shade monolithic zirconia disc specimens in various thicknesses (1.0, 1.5, and 2.0 mm) were fabricated using three brands: Nacera® Pearl 1, DD cubeX2 and XTCERA TT. A spectrophotometer was used to determine the CIELab values of the specimens, which were placed on a D4-shade resin composite and white acrylic (control) substrates. The ∆E was calculated and compared with the acceptable (AT = 5.5) and perceptible (PT = 2.6) tolerance thresholds. Further investigation was conducted on 72-disc specimens from the monolithic zirconia brand with the best masking ability on D3-shade resin composite and semi-precious alloy. Using two-way ANOVA, the interaction of thickness, brand, and abutment substrate on ∆E was investigated. Nacera® Pearl 1 at 1.5 mm thickness was sufficient to achieve AT on a D4-shade resin composite substrate, whereas 2.0 mm of DD cubeX2 and XTCERA TT were required. Nacera® Pearl 1 further testing on two other substrates requires thicknesses of 1.5 mm and 1.0 mm, respectively. Only the Nacera® Pearl 1 group achieved PT on D3- and D4-shade resin composite (2.0 mm) and semi-precious alloy substrates (1.5 mm). Brand, thickness, and abutment substrate influenced the ∆E (p < 0.001). To achieve an acceptable masking ability, the minimum thickness of monolithic zirconia tested on D3- and D4-shade resin composite and semi-precious alloy should be around 1.5 mm to 2.0 mm.

CYP3A4 and CYP3A5 are metabolizing enzymes abundantly expressed in liver and involved in the metabolism of xenobiotics as well as clinically used drugs. Genetic polymorphisms in CYP3A4 and CYP3A5 may alter the metabolic ability of individuals. Thus, CYP3A4 and CYP3A5 might play an important role in the aetiology of chronic myeloid leukaemia (CML) and as modulators of cancer therapy response. In this study, the impact of two single nucleotide polymorphisms (SNPs) CYP3A4*18 (878T>C) and CYP3A5*3 (6986A>G) on CML susceptibility risk was investigated. This case-control study involved a total of 520 study subjects comprising 270 CML patients and 250 normal healthy controls. Genotyping of CYP3A4*18 and CYP3A5*3 was performed by polymerase chain reaction – restriction fragment length polymorphism (PCR-RFLP) technique. The association between allelic variants and CML susceptibility risk was assessed by logistic regression analysis, deriving odds ratio (OR) with 95% confident intervals. The results showed that heterozygous (*1/*1*8) genotype of CYP3A4*18 was significantly associated with CML susceptibility risk (OR 3.387; 95% CI: 1.433–8.007, p = 0.005). No homozygous variant (*18/*18) genotype was detected in this study. On the contrary, homozygous variant (*3/*3) and heterozygous (*1/*3) genotypes of CYP3A5*3 were associated with significantly lower risk for CML susceptibility (OR 0.140; 95% CI: 0.079–0.246’ p < 0.001 and OR 0.310; 95% CI: 0.180–0.535, p < 0.001, respectively). The results prompt us to conclude that genetic variation in CYP3A4*18 may contribute to a higher risk whereas CYP3A5*3 polymorphism confers a lower susceptibility risk in Malaysian CML patients.

Background: Medical training is often regarded as a stressful period. Studies have previously found that 21.6%–50% of medical students experience significant psychological distress. The present study compared the prevalence and levels of psychological distress between 2 cohorts of first-year medical students that underwent different admission selection processes. Methods: A comparative cross-sectional study was conducted by comparing 2 cohorts of first-year medical students; 1 group (cohort 1) was selected based purely on academic merit (2008/2009 cohort) and the other group (cohort 2) was selected based on academic merit, psychometric assessment, and interview performance (2009/2010 cohort). Their distress levels were measured by the General Health Questionnaire, and scores higher than 3 were considered indicative of significant psychological distress. Results: The prevalence (P = 0.003) and levels (P = 0.001) of psychological distress were significantly different between the 2 cohorts. Cohort 1 had 1.2–3.3 times higher risk of developing psychological distress compared to cohort 2 (P = 0.007). Conclusion: Cohort 2 had better psychological health than cohort 1 and was less likely to develop psychological distress. This study provided evidence of a potential benefit of multimodal student selection based on academic merit, psychometric assessment, and interview performance. This selection process might identify medical students who will maintain better psychological health.