Effect of saliva contamination on the bond strength of single-step and three-step adhesive systems

The aim of this study was to evaluate the effect of saliva contamination on bond strength to dentin with an etch-and-rinse and a self-etch adhesive system. For each of these adhesive systems, the dentin surface of 24 human molars were allocated to one of four groups representing different saliva contamination scenarios. Saliva was applied at different stages in the bonding process, and was investigated to be remedied by water rinsing and/or air drying. Uncontaminated tooth surfaces were used as controls. Bonding procedures were performed according to the manufacturer's instructions, and a polymer-based composite was placed. The bond strength was measured by a micro-tensile test. Except for the etch-and-rinse approach having contamination with saliva after etching, followed by air drying, all salivary contamination regimens resulted in a substantial number of specimens not surviving the test, and the bond strength value of these was therefore set to 0 MPa for the purposes of the statistical analysis. Water rinsing after etching and salivary contamination did significantly reduce the bond strength. Contamination after priming showed the lowest bond strength. For the self-etch approach, saliva contamination before the adhesive procedure, followed by air drying, significantly reduced the bond strength, while contamination followed by water rinsing or air drying did not statistically significantly reduce the strength.publishedVersio

Dental Students’ Experiences during the COVID‐19 Pandemic — A Cross‐Sectional Study from Norway

The purpose of this cross-sectional study was to map dental students’ experience of the study situation throughout the pandemic. All clinical dental students (year 3 to 5) at the Faculty of Medicine, Department of Clinical Dentistry (IKO), University of Bergen (UiB), Norway, were invited. Participation was anonymous and voluntary, and the response rate was 63%. Questions regarding stress-related factors were divided into three categories. In the category «Stressors/learning», a statistically significant difference was observed between both the genders (p = 0.001) and years of study (p = 0.028). Statistically significant differences between the genders were also observed in the category «Stressors/infection» (p = 0.008). Women were significantly more stressed due to lack of clinical skills (p = 0.048), not receiving as good theoretical teaching as before the pandemic (p = 0.016), and uncertain issues around the exams (p = 0.000). Fourth year students were significantly more stressed due to lack of clinical skills (p = 0.012), for not passing the clinic/skills courses due to lack of study progression (p = 0.005), and worries about not being a good enough dentist after graduation (p = 0.002). In conclusion, the pandemic had a major impact on dental students. The most prominent stressors in relation to the study situation were experienced by students from the fourth year and female students. Clinical and theoretical learning outcomes among students were regarded as worse than before the pandemic. The students preferred in presence lectures, but experienced digital asynchronous video lectures as a good alternative. The pandemic negatively affected the students’ social life. Dental schools should be aware that students have been exposed to increased distress and burden through the pandemic and should provide support for those in need.publishedVersio

Mercury in human brain, blood, muscle and toenails in relation to exposure: an autopsy study

Background: The main forms of mercury (Hg) exposure in the general population are methylmercury (MeHg) from seafood, inorganic mercury (I-Hg) from food, and mercury vapor (Hg0) from dental amalgam restorations. While the distribution of MeHg in the body is described by a one compartment model, the distribution of I-Hg after exposure to elemental mercury is more complex, and there is no biomarker for I-Hg in the brain. The aim of this study was to elucidate the relationships between on the one hand MeHg and I-Hg in human brain and other tissues, including blood, and on the other Hg exposure via dental amalgam in a fish-eating population. In addition, the use of blood and toenails as biological indicator media for inorganic and organic mercury (MeHg) in the tissues was evaluated. Methods: Samples of blood, brain (occipital lobe cortex), pituitary, thyroid, abdominal muscle and toenails were collected at autopsy of 30 deceased individuals, age from 47 to 91 years of age. Concentrations of total-Hg and I-Hg in blood and brain cortex were determined by cold vapor atomic fluorescence spectrometry and total-Hg in other tissues by sector field inductively coupled plasma-mass spectrometry (ICP-SFMS). Results: The median concentrations of MeHg (total-Hg minus I-Hg) and I-Hg in blood were 2.2 and 1.0 μg/L, and in occipital lobe cortex 4 and 5 μg/kg, respectively. There was a significant correlation between MeHg in blood and occipital cortex. Also, total-Hg in toenails correlated with MeHg in both blood and occipital lobe. I-Hg in both blood and occipital cortex, as well as total-Hg in pituitary and thyroid were strongly associated with the number of dental amalgam surfaces at the time of death. Conclusion: In a fish-eating population, intake of MeHg via the diet has a marked impact on the MeHg concentration in the brain, while exposure to dental amalgam restorations increases the I-Hg concentrations in the brain. Discrimination between mercury species is necessary to evaluate the impact on Hg in the brain of various sources of exposure, in particular, dental amalgam exposure

Dental Students’ Experiences during the COVID-19 Pandemic—A Cross-Sectional Study from Norway

The purpose of this cross-sectional study was to map dental students’ experience of the study situation throughout the pandemic. All clinical dental students (year 3 to 5) at the Faculty of Medicine, Department of Clinical Dentistry (IKO), University of Bergen (UiB), Norway, were invited. Participation was anonymous and voluntary, and the response rate was 63%. Questions regarding stress-related factors were divided into three categories. In the category «Stressors/learning», a statistically significant difference was observed between both the genders (p = 0.001) and years of study (p = 0.028). Statistically significant differences between the genders were also observed in the category «Stressors/infection» (p = 0.008). Women were significantly more stressed due to lack of clinical skills (p = 0.048), not receiving as good theoretical teaching as before the pandemic (p = 0.016), and uncertain issues around the exams (p = 0.000). Fourth year students were significantly more stressed due to lack of clinical skills (p = 0.012), for not passing the clinic/skills courses due to lack of study progression (p = 0.005), and worries about not being a good enough dentist after graduation (p = 0.002). In conclusion, the pandemic had a major impact on dental students. The most prominent stressors in relation to the study situation were experienced by students from the fourth year and female students. Clinical and theoretical learning outcomes among students were regarded as worse than before the pandemic. The students preferred in presence lectures, but experienced digital asynchronous video lectures as a good alternative. The pandemic negatively affected the students’ social life. Dental schools should be aware that students have been exposed to increased distress and burden through the pandemic and should provide support for those in need

Effect of saliva contamination on the bond strength of single-step and three-step adhesive systems

The aim of this study was to evaluate the effect of saliva contamination on bond strength to dentin with an etch-and-rinse and a self-etch adhesive system. For each of these adhesive systems, the dentin surface of 24 human molars were allocated to one of four groups representing different saliva contamination scenarios. Saliva was applied at different stages in the bonding process, and was investigated to be remedied by water rinsing and/or air drying. Uncontaminated tooth surfaces were used as controls. Bonding procedures were performed according to the manufacturer's instructions, and a polymer-based composite was placed. The bond strength was measured by a micro-tensile test. Except for the etch-and-rinse approach having contamination with saliva after etching, followed by air drying, all salivary contamination regimens resulted in a substantial number of specimens not surviving the test, and the bond strength value of these was therefore set to 0 MPa for the purposes of the statistical analysis. Water rinsing after etching and salivary contamination did significantly reduce the bond strength. Contamination after priming showed the lowest bond strength. For the self-etch approach, saliva contamination before the adhesive procedure, followed by air drying, significantly reduced the bond strength, while contamination followed by water rinsing or air drying did not statistically significantly reduce the strength

Dental Students’ Experiences during the COVID‐19 Pandemic — A Cross‐Sectional Study from Norway

The purpose of this cross-sectional study was to map dental students’ experience of the study situation throughout the pandemic. All clinical dental students (year 3 to 5) at the Faculty of Medicine, Department of Clinical Dentistry (IKO), University of Bergen (UiB), Norway, were invited. Participation was anonymous and voluntary, and the response rate was 63%. Questions regarding stress-related factors were divided into three categories. In the category «Stressors/learning», a statistically significant difference was observed between both the genders (p = 0.001) and years of study (p = 0.028). Statistically significant differences between the genders were also observed in the category «Stressors/infection» (p = 0.008). Women were significantly more stressed due to lack of clinical skills (p = 0.048), not receiving as good theoretical teaching as before the pandemic (p = 0.016), and uncertain issues around the exams (p = 0.000). Fourth year students were significantly more stressed due to lack of clinical skills (p = 0.012), for not passing the clinic/skills courses due to lack of study progression (p = 0.005), and worries about not being a good enough dentist after graduation (p = 0.002). In conclusion, the pandemic had a major impact on dental students. The most prominent stressors in relation to the study situation were experienced by students from the fourth year and female students. Clinical and theoretical learning outcomes among students were regarded as worse than before the pandemic. The students preferred in presence lectures, but experienced digital asynchronous video lectures as a good alternative. The pandemic negatively affected the students’ social life. Dental schools should be aware that students have been exposed to increased distress and burden through the pandemic and should provide support for those in need

Mercury in human brain, blood, muscle and toenails in relation to exposure: an autopsy study

Abstract Background The main forms of mercury (Hg) exposure in the general population are methylmercury (MeHg) from seafood, inorganic mercury (I-Hg) from food, and mercury vapor (Hg0) from dental amalgam restorations. While the distribution of MeHg in the body is described by a one compartment model, the distribution of I-Hg after exposure to elemental mercury is more complex, and there is no biomarker for I-Hg in the brain. The aim of this study was to elucidate the relationships between on the one hand MeHg and I-Hg in human brain and other tissues, including blood, and on the other Hg exposure via dental amalgam in a fish-eating population. In addition, the use of blood and toenails as biological indicator media for inorganic and organic mercury (MeHg) in the tissues was evaluated. Methods Samples of blood, brain (occipital lobe cortex), pituitary, thyroid, abdominal muscle and toenails were collected at autopsy of 30 deceased individuals, age from 47 to 91 years of age. Concentrations of total-Hg and I-Hg in blood and brain cortex were determined by cold vapor atomic fluorescence spectrometry and total-Hg in other tissues by sector field inductively coupled plasma-mass spectrometry (ICP-SFMS). Results The median concentrations of MeHg (total-Hg minus I-Hg) and I-Hg in blood were 2.2 and 1.0 μg/L, and in occipital lobe cortex 4 and 5 μg/kg, respectively. There was a significant correlation between MeHg in blood and occipital cortex. Also, total-Hg in toenails correlated with MeHg in both blood and occipital lobe. I-Hg in both blood and occipital cortex, as well as total-Hg in pituitary and thyroid were strongly associated with the number of dental amalgam surfaces at the time of death. Conclusion In a fish-eating population, intake of MeHg via the diet has a marked impact on the MeHg concentration in the brain, while exposure to dental amalgam restorations increases the I-Hg concentrations in the brain. Discrimination between mercury species is necessary to evaluate the impact on Hg in the brain of various sources of exposure, in particular, dental amalgam exposure.</p