Effect of Streptococcus mutans on surface-topography, microhardness, and mechanical properties of contemporary resin composites.

OBJECTIVE: Dental caries is the most prevalent disease globally, and Streptococcus mutans (S. mutans) is a common associated oral bacteria. Additionally, S. mutans possess esterase activity capable of degrading resin composites (RC). However, the effect of degradation on the physical-mechanical properties of the RC has not been extensively studied. We evaluated the flexure strength (FS), the diametral tensile strength (DTS), the modulus of elasticity (ME), and the microhardness of three contemporary RC to establish if S. mutans could affect them. METHODS: One hundred thirty-eight bar-shaped and 276 disc-shaped specimens were fabricated with Enamel Plus HRi, IPS Empress Direct, and Clearfil AP-X, and physical-mechanical testing was done after been incubated during 30 and 60 days in culture media with or without S. mutans. Also, a scanning electron microscope was used to identify surface changes. RESULTS: None of the tested RC were affected in their mechanical properties (FS, ME, and DTS). However, Clearfil AP-X and Enamel Plus HRI showed eroded surfaces and a decreased microhardness after 30 and 60 days S. mutans incubation. IPS Empress Direct presented the lowest values in all the tests, but its physical-mechanical features and surface were not affected by bacteria's exposure. CONCLUSIONS: Exposure to S. mutans could affect some contemporary RC; however, the effect seems superficial since its mechanical features were not affected.

Connecting Theory to Practice: Using Self-Determination Theory To Better Understand Inclusion in STEM.

In the United States, persistence for women and ethnic minorities in science, technology, engineering, and math (STEM) careers is strongly impacted by affective factors such as science identity, agency, and sense of belonging. Policies aimed at increasing the diversity of the national STEM student population and workforce have recently focused on fostering inclusive learning environments that can positively impact the experiences of underrepresented minorities (URMs) in STEM, thus increasing their retention. While research on inclusion in STEM in higher education is relatively new, inclusion research has a rich history in several other disciplines. These fields have developed theoretical frameworks and validated instruments to conceptualize and assess inclusion. Self-determination theory (SDT) is a well-established theoretical framework in educational psychology that states that ones' internal motivation is strongly correlated with the satisfaction of three specific psychological needs: autonomy, competency, and relatedness. In this paper, we introduce SDT and discuss how it relates to inclusion and to ongoing efforts to increase retention of STEM URM students in higher education environments. We argue that grounding inclusion initiatives in the SDT framework increases our understanding of the mechanisms mediating their impact, thus facilitating their reproducibility and generalizability. Finally, we describe how this theoretical framework has been adapted by the field of Industrial and Organizational Psychology to define and assess inclusion in the workplace as an example of how STEM education researchers can use this framework to promote and assess inclusion in their fields.

Midwestern Latino caregivers' knowledge, attitudes and sense making of the oral health etiology, prevention and barriers that inhibit their children's oral health: a CBPR approach.

BACKGROUND: Using community-based participatory research, the Health Protection Model was used to understand the cultural experiences, attitudes, knowledge and behaviors surrounding caries etiology, its prevention and barriers to accessing oral health care for children of Latino parents residing in Central Indiana. METHODS: A community reference group (CBPR) was established and bi-lingual community research associates were used to conduct focus groups comprised of Latino caregivers. Transcripts were analyzed for thematic content using inductive thematic analysis. RESULTS: Results indicated significant gaps in parental knowledge regarding caries etiology and prevention, with cultural underlays. Most parents believed the etiology of caries was related to the child's ingestion of certain foods containing high amounts of carbohydrates. Fewer parents believed either genetics/biological inheritance or bacteria was the primary causative factor. Fatalism negatively impacted preventive practices, and a clear separation existed concerning the perceived responsibilities of mothers and fathers to provide for the oral needs of their children. Females were more likely to report they were primarily responsible for brushing their children's teeth, overseeing the child's diet and seeking dental care for the child. Fathers believed they were primarily responsible for providing the means to pay for professional care. Perceived barriers to care were related to finances and communication difficulties, especially communicating with providers and completing insurance forms. CONCLUSION: The main study implication is the demonstration of how the CBPR model provided enhanced understanding of Latino caregivers' experiences to inform improvements in oral prevention and treatment of their children. Current efforts continue to employ CBPR to implement programs to address the needs of this vulnerable population.

Microbiological profile and incidence of Salmonella and Listeria monocytogenes on hydroponic bell peppers and greenhouse cultivation environment.

The aim of this study was to generate information regarding the microbiological profile, including Salmonella and Listeria monocytogenes incidence, of hydroponically grown bell peppers and materials associated with their production in greenhouses located in Mexico. Samples of coconut fiber (24), knives (30), drippers (20), conveyor belts (161), pepper transportation wagons (30), air (178), water (16), nutrient solution for plant irrigation (78), and bell pepper fruits (528) were collected during one cycle of production (2009 to 2010) for the quantification of microbial indicators (aerobic plate counts [APC], molds, coliforms, and Escherichia coli) and the detection of Salmonella and L. monocytogenes. With regard to surfaces (conveyor belts and wagons) and utensils (knives and drippers), the APC, coliform, and mold counts ranged from 3.0 to 6.0, from 1.4 to 6.3, and from 3.6 to 5.2 log CFU/100 cm(2) or per utensil, respectively. The air in the greenhouse contained low median levels of APC (1.2 to 1.4 log CFU/100 liters) and molds (2.2 to 2.5 log CFU/100 liters). The median content of APC and coliforms in water were 0.5 log CFU/ml and 0.3 log MPN/100 ml, respectively. The median content of coliforms in nutrient solution ranged from 1.8 to 2.4 log MPN/100 ml, and E. coli was detected in 18 samples (range, <0.3 to 1.2 log MPN/100 ml). On bell pepper analyzed during the study, populations (median) of APC, coliforms, and molds were 5.4, 3.6, and 5.8 log CFU per fruit, respectively; E. coli was detected in 5.1% of the samples (range, 0.23 to 1.4 log MPN per fruit). Salmonella was isolated from only one sample (1.6%) of conveyor belt located at the packing area and in four bell pepper samples (3%). L. monocytogenes was not detected. This information could help producers to establish effective control measures to prevent the presence of foodborne pathogens in bell peppers based on a scientific approach.