Effects of Autoclave Sterilization on Cyclic Fatigue Resistance in 5 Types of Rotary Endodontic Instruments: An In Vitro Study.

BACKGROUND Rotary endodontic instruments are increasingly used in root canal treatment and have replaced stainless steel manual files. Cyclic fatigue is the cyclic loading of stress to produce deformation or fracture. This study aimed to evaluate and compare the effects of autoclave sterilization on cyclic fatigue in 5 types of rotary endodontic instruments. MATERIAL AND METHODS ProTaper Universal, BioRace, ProTaper Next, Twisted File, and HyFlex CM instruments were included in this study. Each type included 96 instruments, divided into 4 groups according to the number of sterilization cycles (0, 1, 3, 5). After sterilization, each group of instruments was divided into 2 subgroups and tested for cyclic fatigue in 2 simulated canals (45 degrees both and 2 radii, 2 mm and 5 mm). The number of cycles to failure (NCF) was calculated, and statistical analyses were carried out using the t test, Mann-Whitney U test, and ANOVA, followed by the Tukey post hoc test (p<0.05). Fracture surfaces were analyzed using scanning electron microscopy (SEM). RESULTS Within the group of non-sterilized instruments, ProTaper Universal showed significantly lower resistance to cyclic fatigue compared to the other types of instruments (p<0.001). After repeated sterilization, a significantly higher mean of NCF was observed for BioRace (p<0.001), ProTaper Next (p<0.001), Twisted File (p<0.001), and HyFlex CM (p<0.001) compared to ProTaper Universal. The resistance of HyFlex CM was significantly higher compared to the other types of instruments (p<0.001). CONCLUSIONS The findings from this study showed that autoclave sterilization of newer rotary endodontic instruments could increase resistance to cyclic fatigue.

Cancer of unknown primary - incidence, mortality trend, and mortality-to-incidence ratio is associated with human development index in Central Serbia, 1999-2018: Evidence from the national cancer registry.

OBJECTIVES: The aim was to estimate the trend of incidence, mortality and mortality-to-incidence ratio (MIR) in Central Serbia in 1999-2018 and its possible association with the human development index (HDI). METHODS: In this study, cancer of unknown primary (CUP) was included as C77-C80 codes. Trend analysis was performed in the Joinpoint Regression Programme version 4.8.0.1. HDI combines life expectancy, educational attainment and gross national income. HDI values for Serbia are extracted from the global bank site. RESULTS: Joinpoint regression analysis of the age-standardised incidence rate of CUP showed a significantly increasing trend with annual percent change (APC) of 8.5% (95% confidence interval [CI] 3.0-14.3%) in males and 7.8% (95%CI 2.7-13.2) in females. The age-standardised mortality rate of CUP showed a significantly decreasing trend with APC of -1.7% (95%CI -2.8 to -0.5%) in males and -1.4% (95%CI -2.7 to -0.1%) in females. MIR showed a significantly decreasing trend with APC of -9.3% (95%CI -14.6 - -3.6%) in males and -7.1% (95%CI -10.5% to -4.2%) in females. The linear regression showed significant inverse association among HDI and the MIR of CUP in males (r2 = 0.464, p = 0.002) and in females (r2 = 0.612, p < 0.001). CONCLUSIONS: Decline of MIR was associated with HDI, suggesting that CUP prognosis follows socio-economic status.

Influence of etching mode and composite resin type on bond strength to dentin using universal adhesive system.

Adhesive bond strength at the composite/dentin interface is influenced by various factors, including the etching mode and composite resin type. The purpose of this study was to evaluate the influence of the total-etch and self-etch mode on the microtensile bond strength (µTBS) of conventional and bulk-fill composite to dentin, using the universal adhesive system. Sixty non-carious human teeth were sectioned parallel to their longitudinal axis, using a low-speed diamond saw to obtain a flat dentin surface. According to the etching technique and composite resin type used, teeth were randomly divided into four different groups (n = 15): TC (total-etch/conventional composite), TB (total-etch/bulk-fill composite), SC (self-etch/conventional composite), and SB (self-etch/bulk-fill composite). Cylindric composite build-ups were made with 3M Filtek Z250 and 3M Filtek Bulkfill Posterior, using a plastic mold, 4 mm in diameter and 4 mm in height. The specimens were subjected to the µTBS test in a universal testing machine and failure force was recorded. Failure modes were determined using stereoscopic and scanning electron microscopy. Data were analyzed using the two-way ANOVA and Student's t test. The µTBS was significantly affected by the etching technique. A significant statistical difference was determined between total-etch and self-etch groups, irrespective of the composite resin type used. Higher bond strength was obtained in total-etch groups. The µTBS was not affected by the composite resin type. No significant statistical difference was determined between the conventional and bulk-fill groups, irrespective of the etching-mode.

Impact of socio-demographic characteristics and long-term complications on quality of life in patients with diabetes mellitus.

OBJECTIVE: Diabetes mellitus (DM) has been one of the leading chronic diseases worldwide over past decades. The objective of the study was to identify predictors associated with health-related quality of life (HRQOL) in diabetic patients. METHODS: A cross-sectional questionnaire-based study was conducted at the General Hospital of the city of Leskovac, between June and November 2015. The Short Form-36 (SF-36) questionnaire, EuroQol-5D (EQ-5D) and EuroQol-VAS (EQ-VAS) questionnaires were used. Univariate and multivariate linear regression analyses were performed. RESULTS: The total number of patients was 285, 112 men (39.3%) and 173 women (60.7%), average age 63.92 ± 1.07 years. The results of multiple linear regression of socio-demographic characteristics in relation to dimensions of the quality of life measured by SF-36 and EQ-VAS showed that age, country (rural) life, low level of education, retirement, and poor economic status are predictors of lower quality of life. Our results showed that employment has a significant association with higher Physical Component Score (PCS), Mental Component Score (MCS) and EQ-VAS score, which can be explained with higher incomes, improved economic status and less possibility for the occurrence of depressive mood. Patients without formal education have lower QOL. Univariate multiple regression analysis of the presence of micro- and macrovascular complications of DM showed that angina pectoris, heart failure, diabetic retinopathy, and diabetic nephropathy are the most important factors affecting the quality of life in our population. After including the multivariate model, all tested complications remained statistically significant. CONCLUSION: Our results showed that both socioeconomic and chronic complications are relevant factors of HRQOL in type 1 and 2 diabetes mellitus patients. Age, rural lifestyle, retirement, lower level of education and low socioeconomic status, as well as DM complications (angina pectoris, hearth failure, diabetes nephropathy, and diabetes retinopathy) were found to be independent risk factors for the component scores of SF-36 and EQ-VAS score. Taking into consideration the results obtained, health practitioners should be aware not only of the clinical parameters of patients with DM, but also of their educational level and working status.

Progress of statistical analysis in biomedical research through the historical review of the development of the Framingham score.

BACKGROUND: The interest in developing risk models in medicine not only is appealing, but also associated with many obstacles in different aspects of predictive model development. Initially, the association of biomarkers or the association of more markers with the specific outcome was proven by statistical significance, but novel and demanding questions required the development of new and more complex statistical techniques. METHODS: Progress of statistical analysis in biomedical research can be observed the best through the history of the Framingham study and development of the Framingham score. RESULTS: Evaluation of predictive models comes from a combination of the facts which are results of several metrics. Using logistic regression and Cox proportional hazards regression analysis, the calibration test, and the ROC curve analysis should be mandatory and eliminatory, and the central place should be taken by some new statistical techniques. In order to obtain complete information related to the new marker in the model, recently, there is a recommendation to use the reclassification tables by calculating the net reclassification index and the integrated discrimination improvement. Decision curve analysis is a novel method for evaluating the clinical usefulness of a predictive model. It may be noted that customizing and fine-tuning of the Framingham risk score initiated the development of statistical analysis. CONCLUSION: Clinically applicable predictive model should be a trade-off between all abovementioned statistical metrics, a trade-off between calibration and discrimination, accuracy and decision-making, costs and benefits, and quality and quantity of patient's life.

Does short-term air pollution exposure have effects on blood pressure and heart rate in healthy women in the city of Nis, Serbia?

OBJECTIVE: Epidemiological research has shown that air pollution is associated with cardiovascular events, but little is known about short-term effects on blood pressure (BP) and heart rate (HR) in Serbian population. The present study assessed the short-term association between black smoke (BS) and sulphur dioxide (SO2) levels in urban air and the daily values of blood pressure and heart rate in 98 healthy nonsmoking female volunteers. METHODS: Generalized regression model was fitted controlling for temperature, relative humidity, air pressure, season, and the day of the week. RESULTS: There was no association between short-term air pollution exposure and BP and HR, the exposure showed a tendency toward a decrease of diastolic BP and HR, but with no statistical significance. CONCLUSION: The present findings did not support the conclusion that current levels of ambient BS and SO2 may have an effect on blood pressure and heart rate in women.