Effect of color of the cement and the composite resin foundation on the resultant color of resin-matrix ceramics

Statement of problemAn improper restoration color match to the adjacent natural teeth can jeopardize esthetic success. The type of resin-matrix ceramic (RMC), the shade of the underlying foundation, and the shade of cement may affect the optical behavior of RMC materials, but studies on this issue are lacking.PurposeThe purpose of this in vitro study was to assess the cumulative effect of different shades of composite resin foundation (CRF) and cement on the optical behaviors of 3 different RMCs.Material and methodsForty-five rectangular RMC specimens (14×12×1 mm, shade A2) were prepared from 3 different blocks, including a polymer-infiltrated ceramic network (Vita Enamic [VE]), a resin nanoceramic (Lava Ultimate [LU]), and a flexible nanoparticle-filled resin (GC Cerasmart [GC]) (n=15 per RMC block). CRFs (14×12×4 mm) were fabricated in white and dentin shades (n=1 per composite resin shade). Cement specimens (G-CEM LinkForce) were prepared from 3 shades (A2, opaque [OP], and translucent [TR]) (n=15 per shade). For control groups, 3 rectangular RMC foundations (14×12×4 mm) were also milled from RMC blocks (n=1 per block). Color coordinates were recorded by using a digital spectrophotometer. The coordinates of 4-mm-thick RMC foundations served as the control groups. The coordinates of RMC specimens on each combination of CRF and cement served as test groups. The CIEDE2000 (ΔE₀₀) formula was used to assess color differences. Data were subjected to 3-way ANOVA and Tukey honestly significant difference (HSD) tests (α=.05).ResultsΔE₀₀ values of specimens were influenced by the CRF shade, cement shade, RMC type, as well as the interaction terms of the 3 variables (P<.001). Color differences in groups VE-A2-dentin, VE-OP-dentin, LU-OP-dentin, and GC-OP-dentin showed perceptible but clinically acceptable values (0.8<ΔE₀₀≤1.8). The highest and lowest ΔE₀₀ values were observed in the white-OP-LU (5.32 ±0.34) and dentin-OP-VE (0.94 ±0.31) groups.ConclusionsOpaque cement on the white foundation led to the highest ΔE₀₀ values in the resultant colors of all RMC groups. When used with the same shade on the dentin foundation, this cement produced clinically acceptable results.     

The impact of gender and physical environment on the handwashing behaviour of university students in Ghana

Objectives To establish levels of handwashing after defecation among students at the University of Cape Coast in Ghana, and to test hypotheses that gender and washroom environment affect handwashing behaviour. Methods Data on students’ handwashing behaviour after defecation were collected by structured observations in washrooms. Eight hundred and six observations were made (360 female students and 446 males) in 56 washrooms over 496 observation periods. Observers recorded gender, duration of handwashing, use of soap, and physical characteristics of the washroom (cleanliness, availability of soap, tap flow and presence of handwashing posters). Results Fewer than half the students observed washed their hands or bathed after defecation. Of these, only two‐thirds washed both hands and a minority (20%) used soap; only 16 students (all men) washed their hands for the recommended 15 s or longer. Female students were more likely to wash their hands at all, and were more likely to wash both hands, than males. Cleanliness of the washroom was strongly associated with improved handwashing behaviour for both women and men, as was tap flow quality for female students. Conclusions Handwashing behaviour is generally poor among UCC students, mirroring results from North American Universities. The findings underline the plasticity of handwashing behaviour among this population, and highlight the need for ensuring that the physical environment in washrooms on university campuses is conducive to handwashing.     

Distribution of gene mutations associated with familial normosmic idiopathic hypogonadotropic hypogonadism

Objective: Normosmic idiopathic hypogonadotropic hypogonadism (nIHH) is characterized by failure of initiation or maintenance of puberty due to insufficient gonadotropin release, which is not associated with anosmia/hyposmia. The objective of this study was to determine the distribution of causative mutations in a hereditary form of nIHH. Methods: In this prospective collaborative study, 22 families with more than one affected individual (i.e. multiplex families) with nIHH were recruited and screened for genes known or suspected to be strong candidates for nIHH. Results: Mutations were identified in five genes (GNRHR, TACR3, TAC3, KISS1R, and KISS1) in 77% of families with autosomal recessively inherited nIHH. GNRHR and TACR3 mutations were the most common two causative mutations occurring with about equal frequency. Conclusions: Mutations in these five genes account for about three quarters of the causative mutations in nIHH families with more than one affected individual. This frequency is significantly greater than the previously reported rates in all inclusive (familial plus sporadic) cohorts. GNRHR and TACR3 should be the first two genes to be screened for diagnostic purposes. Identification of causative mutations in the remaining families will shed light on the regulation of puberty.     

Assessment of Endothelial Function in Alzheimer's Disease: Is Alzheimer's Disease a Vascular Disease?

OBJECTIVES: To compare endothelial function of people with Alzheimer's disease (AD) with that of people without. DESIGN: Case-control study. SETTING: Geriatric medicine outpatient clinic of a university hospital. PARTICIPANTS: Twenty-five patients with AD who were free of vascular risk factors and 24 healthy elderly controls were enrolled. Exclusion criteria were diabetes mellitus, hypertension, dyslipidemia, evident stroke, smoking, documented coronary artery disease, history of myocardial infarction, heart failure, acute or chronic infection, malignancy, peripheral artery disease, renal disease, rheumatologic diseases, alcohol abuse, and certain drugs that may affect endothelial function. Both groups underwent comprehensive geriatric assessment and neuropsychiatric assessment. MEASUREMENTS: Endothelial function was evaluated according to flow-mediated dilation (FMD) from the brachial artery. RESULTS: Mean age +/- standard deviation was 78 +/- 5.9 in the group with AD (11 female and 14 male) and 72.1 +/- 5.8 in the control group (9 female and 11 male). Multiple linear regression analysis revealed that FMD was significantly lower in patients with AD (median 3.45, range 0-7) than controls (median 8.41, range 1-14) (P < .001), independent of age. It was also found that FMD values were inversely correlated with the stage of the disease as determined according to the Clinical Dementia Rating scale (r=-0.603, P < .001). CONCLUSION: Endothelial function is impaired in patients with AD. Endothelial function was worse in patients with severe AD. These findings provide evidence that vascular factors have a role in the pathogenesis of AD.     

The effect of cyclosporin A on alveolar bone in rats subjected to experimental periodontal disease

Cyclosporine A (CsA), broadly used in organ transplantation, may contribute to pathogenesis of osteoporosis. The aim of this study was to investigate the effects of CsA on alveolar bone in rats subjected or not to experimental periodontal disease using biochemical, radiographic, and histometric analysis. Forty Wistar rats were divided into 4 equal groups: Group I (Control), Group II (CsA was injected subcutaneously in a daily dose of 10 mg/kg), Group III (Ligature was placed around the mandibular molars), Group IV (Ligature+CsA). After 60 days, rats were decapitated, serum alkaline phosphatase and calcium levels were measured. Radiographic-alveolar bone loss (ABL), histometric-ABL, and percentage of new alveolar bone formation (NABF%) were determined on mandibular molars. Significant increase in serum alkaline phosphatase levels (p < 0.001), no significant difference in calcium levels were observed (p > 0.05) in Group IV compared to Group III. Radiographic and histometric-ABL were significantly less (p < 0.001), NABF% was significantly greater (p < 0.05) in Group IV than in Group III. No significant difference in any of the parameters between Group II and Group I was found. It can be concluded that in the presence of periodontal disease, CsA treatment may bring out an imbalance in the alveolar bone homeostasis by decreasing resorption and stimulating formation of alveolar bone in rats.