Simulation-based evaluation of school reopening strategies during COVID-19: A case study of São Paulo, Brazil.

During the coronavirus disease 2019 (COVID-19) pandemic, many countries opted for strict public health measures, including closing schools. After some time, they have started relaxing some of those restrictions. To avoid overwhelming health systems, predictions for the number of new COVID-19 cases need to be considered when choosing a school reopening strategy. Using a computer simulation based on a stochastic compartmental model that includes a heterogeneous and dynamic network, we analyse different strategies to reopen schools in the São Paulo Metropolitan Area, including one similar to the official reopening plan. Our model allows us to describe different types of relations between people, each type with a different infectiousness. Based on our simulations and model assumptions, our results indicate that reopening schools with all students at once has a big impact on the number of new COVID-19 cases, which could cause a collapse of the health system. On the other hand, our results also show that a controlled school reopening could possibly avoid the collapse of the health system, depending on how people follow sanitary measures. We estimate that postponing the schools' return date for after a vaccine becomes available may save tens of thousands of lives just in the São Paulo Metropolitan Area compared to a controlled reopening considering a worst-case scenario. We also discuss our model constraints and the uncertainty of its parameters.

Periodontitis as a risk factor for head and neck cancer.

BACKGROUND: Periodontitis may be associated with the development of head and neck cancer (HNC). A literature review was conducted to understand the possible association between them. MATERIAL AND METHODS: Articles published in the PubMed database from January 1999 and May 2020 were retrieved. Limitations of the studies and biological mechanisms were discussed. RESULTS: A total of 4,232 articles were found. Of these, 13 were analyzed according to inclusion criteria. Most papers found some association between periodontitis and HNC, although differences in periodontal evaluation, sample size, study design and tumor sites were observed. Porphyromonas gingivalis appears to increase the chance of both diseases, and it may be one of their main potential risk factors. Genetic predisposition is increased by exposure to environmental factors which can directly induce epigenetic changes that contribute to these diseases. CONCLUSIONS: Understanding the mechanisms related to periodontitis and HNC has increased, however, well-designed clinical studies are needed for better conclusions. Furthermore, the advent of multiple "omic" technologies will help comprehend their possible association.

Incidence and profile of benign epithelial tumors of salivary glands from a single center in Northeast of Brazil.

BACKGROUND: Benign tumors of the salivary glands are a group of lesions with varied histopathological and clinical spectrum. The aim was to determine the incidence and clinicopathological characteristics of benign salivary gland neoplasms diagnosed between 2007 and 2016 in a single center located in northeastern Brazil. MATERIAL AND METHODS: Records regarding sex, age, anatomical location, histopathological subtype and treatment were retrieved, and data were analyzed using the Stata/IC software (version 12.0). RESULTS: There were above 7,100 cases of neoplasms in the head and neck region, of which 403 corresponded to salivary gland neoplasms. Of these, 238 (59%) were benign, being pleomorphic adenoma (PA) the most frequent neoplasm (n=178; 74.8%), followed by Warthin's tumor (WT) (n=23; 9.7%). Overall, most cases occurred in females (n=136; 57.1%) and age ranged from 11 to 83 years. The parotid gland (n=188; 79%) was the most common anatomical site, and all patients were treated by surgical excision. Of the cases diagnosed as PA, malignant transformation to carcinoma ex-pleomorphic adenoma (CAEXPA) occurred in 7 (3.9%) cases. CONCLUSIONS: The present study confirmed the clinical and demographic profile of benign salivary gland neoplasms, which contributes to the continuous knowledge of current data about these lesions.

Retrospective study of 289 odontogenic tumors in a Brazilian population.

BACKGROUND: Odontogenic tumors (OTs) are considered important among oral lesions because of their clinicopathological heterogeneity, and variable biological behavior. This paper aims to determine the frequency and distribution of OTs, over a period of 10 years, at a public university in Northeastern Brazil and compare this data with previous reports. MATERIAL AND METHODS: We reviewed all cases of OTs from oral pathology laboratory of University of Pernambuco (UPE), from 2004 to 2014. Diagnoses were re-evaluated and the tumors were classified according to the latest (2005) World Health Organization Classification of Tumors. In addition, we searched in the English-language literature retrospective studies on OTs that used the same classification. RESULTS: Within the total of 6028 oral biopsies, 289 (4.79%) were OTs. Of these, 287 (99.3%) were benign and 2 (0.7%) were malignant. The overall incidence was 31.1/million. Mandible-maxilla ratio was 2.5:1 and mean age 35 years. Keratocystic odontogenic tumor (KCOT) (34.6%) was the most frequent lesion, followed by ameloblastoma (AMB) (32.9%) and odontoma (ODO) (11.4%). CONCLUSIONS: OTs are uncommon neoplasms with geographic variation. Our clinicopathological features are according to literature. In the present study, KCOT was the most frequent one, showing that the new classification of OTs altered the distribution of these lesions and possibly made KCOT the most common OT observed in diagnostic services worldwide.