Parametric modelling of survival following HIV and AIDS in the era of highly active antiretroviral therapy: data from Australia

Parametric survival models have not previously been applied to survival following a diagnosis of HIV/ AIDS in Australia. Four different parametric models-exponential, Weibull, log-normal and log-logistic-were applied to data both on HIV-positive cases and on cases diagnosed with AIDS collected through the national HIV/AIDS surveillance system. Using likelihood based goodness-of-fit criteria the Weibull model was found to be the best-fitted model for predicting survival following a diagnosis of HIV infection without and with a diagnosis of AIDS. Several covariates-age, sex, combined HIV exposure category, CD4 cell counts, antiretroviral treatment and AIDS-defining illnesses-were included in the parametric model to predict factors associated with future mortality. Predicted deaths were in agreement with the observed deaths following HIV infection and AIDS. The Weibull model will be applied for future projections of deaths from HIV/AIDS

Comparison of two methods for eliminating the bleached enamel surface roughness

Vital bleaching technique is an effective method for reducing the teeth discolorations. The results of previous studies have shown that carbamide peroxide causes enamel surface roughness, so the enamel stain susceptibility increases. The purpose of this study was to compare two methods for elimination of the bleached enamel surface roughness. In this Parallel interventional study, 60 sound bovine insicors, [5x5x10mm] were selected. After 14 days of vital bleaching with 20% opalescence gel, the specimens were randomly divided into three groups of 20; i Bond group: the enamel surface was covered by a self etch adhesive [i Bond]; Fluoride group: the enamel surface was polished by a rubber cap and was treated by 2.7% Acidulated phosphate fluoride; Control group: no surface treatment was done. In order to evaluate the lasting of each method, half of the specimens in each group were thermocycled. Data were analyzed using Kruskal-WaIlis and Mann-Whitney tests [alpha=0.05]. The control group revealed a higher degree of roughness than i bond and fluoride groups before thermo cycling [P<0.05]. No significant difference was observed in roughness degree between i Bond and fluoride group before thermocycling [P>0.05].The fluoride group revealed a lower roughness degree than the other groups after thermocycling [P<0.05]. For prevention of enamel stain susceptibility after vital bleaching, polishing with rubber cap and fluoride is an effective method for elimination of the enamel surface roughness