For much human activity there exists a 'lateral preference', that is a tendency to use one side of the body or the other; with respect to the hands for example, the vast majority of individuals have a preference for either the right or left hand. Most experts agree that mastication is no exception in that there is a 'preferred chewing side' but the determination of this preference is somewhat complex. This research analyses the mastication of 60 healthy subjects by means of preferred chewing side or 'PCS' tests, the Kazazoglu test, and kinesiography (KGF). While some authors consider the PCS to be the side which first comes into contact with the food we prefer to define it as the side on which the majority of the cycles analysed and registered take place. The objective of this research was to analyse the relationship that might exist between the two different methods used for determining a lateral chewing preference. Although there was no statistically significant agreement between the two techniques, both reflected the fact that there was a marked preference for the right hand side.

It is difficult to determine the existence of a normal or physiological masticatory cycle, because there exists great individual diversity. This study presents some data about two parameters of masticatory cycles according to the frontal plane, i.e. the area and length of right-sided and left-sided cycles in a group of 30 young people, 18 women and 12 men. For our study the Myotronics K6-1 kinesiograph was used. It registers the magnetic field and allows us to obtain graphic recordings of the jaw movement in the three space planes. Other authors have analysed these parameters, but none of those reviewed provides information about the distribution to each side or according to the gender of sampling subjects selected for the analysis. We have tried to describe the normal morphology of the masticatory cycles and, also, establish a reference so as to provide help in the diagnosis of the functional pathology of the masticatory system.

Background Cystic echinococcosis (CE) caused by Echinococcus granulosus sensu lato (s.l.) is a neglected and underdiagnosed parasitic zoonosis that has a significant socioeconomic impact on rural communities relying on livestock farming. CE is endemic across Latin America, including Chile, where the Coquimbo region exhibits a relatively high record of hospital-based human cases and infected animals. However, the incidence of hospitalized CE cases may underestimate the real burden of infection in a population, since the majority of cases never reach medical attention or official disease records. Methodology/Principal findings In 2019, a cross-sectional, community-based study was conducted with the objectives of estimating for the first time the prevalence of human abdominal CE using abdominal ultrasound (US) screening in volunteers residing in urban and rural localities of the Monte Patria municipality located in Limarí province, Coquimbo region, Chile, and identifying the risk factors associated with human infection. Pre-screening activities included a 16-h lecture/hands-on training aimed at rural physicians that focused on the diagnosis of CE by US, based on current WHO recommendations. A total of 2,439 (~8% of municipality inhabitants) people from thirteen target localities were screened by abdominal US in June-July 2019. We found an overall CE prevalence of 1.6% (95% CI 1.1–2.2) with a significantly higher likelihood of infection in rural localities, older age classes and people drinking non-potable water; 84.6% of infected volunteers were newly diagnosed with CE. Cysts were either in active or inactive stages in equal proportions; active cysts were detected in all age classes, while 95.7% of inactive cysts occurred in >40 years-old subjects. Conclusions/Significance This is the first US survey aimed at detecting human infection caused by Echinococcus granulosus s.l. in Chile. Our findings indicate a high CE prevalence in the area, and contribute to define the demographic and behavioral risk factors promoting the transmission of the parasitic infection within target communities. Our results support the implementation of cost-effective strategies for the diagnosis, treatment and control of CE, and the need to improve the epidemiological surveillance system in Chile.

The main objective of this study was to estimate the performance, under local epidemiological conditions, of two in-house ELISA assays for the combined detection of anti-SARS-CoV-2 IgA, IgM, and IgG immunoglobulins. A total of 94 serum samples were used for the assessment, where 44 corresponded to sera collected before the pandemic (free of SARS-CoV-2 antibodies), and 50 sera were collected from confirmed COVID-19 patients admitted to the main public hospital in the city of Valdivia, southern Chile. The Nucleocapsid (Np) and the receptor-binding domain (RBD) proteins were separately used as antigens (Np and RBD ELISA, respectively) to assess their diagnostic performance. A receiver operating characteristic (ROC) analysis was performed to estimate the optical density (OD) cut-off that maximized the sensitivity (Se) and specificity (Sp) of the ELISA assays. Np ELISA had a mean Se of 94% (95% CI = 83.5–98.8%) and a mean Sp of 100% (95% CI = 92.0–100%), with an OD 450 nm positive cut-off value of 0.88. On the other hand, RBD ELISA presented a mean Se of 96% (95% CI = 86.3–99.5%) and a mean Sp of 90% (95% CI = 78.3–97.5%), with an OD 450 nm positive cut off value of 0.996. Non-significant differences were observed between the Se distributions of Np and RBD ELISAs, but the latter presented a significant lower Sp than Np ELISA. In parallel, collected sera were also analyzed using a commercial lateral flow chromatographic immunoassay (LFCI), to compare the performance of the in-house ELISA assays against a commercial test. The LFCI had a mean sensitivity of 94% (95% CI = 87.4–100%) and a mean specificity of 100% (95% CI = 100–100%). When compared to Np ELISA, non-significant differences were observed on the performance distributions. Conversely, RBD ELISA had a significant lower Sp than the LFCI. Although, Np ELISA presented a similar performance to the commercial test, this was 2.5 times cheaper than the LFCI assay (labor cost not considered). Thus, the in-house Np ELISA could be a suitable alternative tool, in resource limited environments, for the surveillance of SARS-CoV-2 infection, supporting further epidemiological studies.

The use of acid etching in conjunction with both conventional and laser cavity preparation improves the adhesion of the materials used in obturation to enamel surfaces.