In less than four months, an unprecedented pandemic changed the world scenario, closing institutions and commerce, paralyzing sports championships, blocking frontiers, and putting almost all populations in a house quarantine regimen. Immunocompromised patients are within the high-risk group to severe outcomes from COVID-19. However, there is no clear evidence of the association between impaired immune host status and complications from SARS-CoV-2 infection so far. The virus is transmitted by inhalation or direct contact with infected secretions, and therefore the dental office is a highly susceptible environment for such transmission. Here, we review the literature and discuss immunological COVID-19 related issues. We also make suggestions for immunocompromised patients’ support in this new emerging context of clinical dental practice. Until comprehensive findings are published, individuals with impaired immunity should be considered as high-risk. Cross infection control procedures for the clinical care of immunocompromised patients should follow the same guidelines that are being proposed for immunocompetent ones. However, during the active outbreak, people under immunosuppressive conditions should not receive elective procedures, even if they do not have symptoms or exposure history to COVID-19, and in case of emergence, care must be done in a separate airborne room. In the pos-pandemic phase, the dental care general recommendations should be the same for all subjects. Changes in the current guidelines have been proposed to SARS-CoV-2 infection control in order to provide the best and safe dental practice. However, they still need to be validated by future studies.

Abstract In less than four months, an unprecedented pandemic changed the world scenario, closing institutions and commerce, paralyzing sports championships, blocking frontiers, and putting almost all populations in a house quarantine regimen. Immunocompromised patients are within the high-risk group to severe outcomes from COVID-19. However, there is no clear evidence of the association between impaired immune host status and complications from SARS-CoV-2 infection so far. The virus is transmitted by inhalation or direct contact with infected secretions, and therefore the dental office is a highly susceptible environment for such transmission. Here, we review the literature and discuss immunological COVID-19 related issues. We also make suggestions for immunocompromised patients’ support in this new emerging context of clinical dental practice. Until comprehensive findings are published, individuals with impaired immunity should be considered as high-risk. Cross infection control procedures for the clinical care of immunocompromised patients should follow the same guidelines that are being proposed for immunocompetent ones. However, during the active outbreak, people under immunosuppressive conditions should not receive elective procedures, even if they do not have symptoms or exposure history to COVID-19, and in case of emergence, care must be done in a separate airborne room. In the pos-pandemic phase, the dental care general recommendations should be the same for all subjects. Changes in the current guidelines have been proposed to SARS-CoV-2 infection control in order to provide the best and safe dental practice. However, they still need to be validated by future studies.

Os linfangiomas são tumores hamartomatosos benignos dos vasos linfáticos. O Wilms Tumor 1 (WT1) é um fator de transcrição que se encontra ativo em algumas neoplasias humanas. A expressão da proteína WT1 é observada em células endoteliais durante a angiogênese e pode ser um marcador útil para distinguir as proliferações vasculares das malformações vasculares. O objetivo deste estudo foi relatar uma série de casos de linfangiomas orais e avaliar a expressão imunoistoquímica da proteína WT1. Dezessete casos de linfangiomas orais foram recuperados e revisados. A análise imunoistoquímica foi realizada e amostras de granuloma piogênico foram utilizadas como controle positivo. A relação homem/mulher foi de 1,125 e a maioria das lesões acometeram pacientes jovens. Enquanto o granuloma piogênico mostrou uma imunopositividade para WT1, as células endoteliais da fina parede dos vasos linfáticos dilatados apresentaram-se negativas para esta proteína. Tais achados reforçam a idéia de que o linfangioma oral é uma malformação vascular caracterizada por dilatação linfática sem uma proliferação endotelial significativa

Lymphangiomas are benign hamartomatous lesions of lymphatic vessels. Wilms Tumor 1 (WT1) is a transcription factor that is activated in some human neoplasias. WT1 protein expression is observed in endothelial cells during angiogenesis and is a useful marker to distinguish between vascular proliferations and vascular malformations. The purpose of the present study is to report a case series of oral lymphangiomas together with an immunohistochemical investigation of WT1. Seventeen cases of oral lymphangioma were retrieved and reviewed. Immunohistochemical analysis of WT1 protein was performed and pyogenic granuloma samples were used as positive controls. The male/female ratio was 1.125 and most of the lesions occurred in young subjects. While pyogenic granuloma showed positive staining for WT1, the endothelial cells lining the thin-walled dilated lymphatic vessels of lymphangiomas were negative for this protein. The findings strengthen the idea that oral lymphangioma is a vascular malformation characterized by lymphatic dilatation without significant endothelial proliferation.

Consideráveis evidências indicam que mecanismos serotoninérgicos, particularmente o transportador de serotonina, estão envolvidos no alcoolismo e no uso de fumo e são influenciados pelo polimorfismo da região promotora do 5HTT (5-HTTLPR). Como o consumo de álcool e fumo está implicado na patogênese do câncer, o objetivo deste estudo foi investigar o polimorfismo 5-HTTLPR em pacientes com carcinoma bucal de células escamosas (CBCE) comparado com um grupo controle em uma amostra de pacientes brasileiros. Cento e três pacientes afetados por CBCE e 103 voluntários sem história de CBCE foram genotipados para 5-HTTLPR. Ambos os grupos foram pareados pela idade, gênero e uso de fumo. O teste do qui-quadrado foi usado para análise estatística. Não houve diferença estatística entre os genótipos dos grupos caso e controle (p= 0,408). Concluindo, a presente investigação demonstrou que os polimorfismos do transportador de serotonina não estão implicados no desenvolvimento do CBCE.

Considerable evidence indicates that serotonergic mechanisms, particularly the serotonin transporter, are involved in alcoholism and tobacco use and are influenced by polymorphism of the promoter region of 5HTT (5-HTTLPR). As alcohol and tobacco consumption have been implicated in the pathogenesis of oral cancer, the purpose of this study was to investigate 5-HTTLPR polymorphism in patients with oral squamous cell carcinoma (OSCC) compared with a control group in a sample of Brazilian patients. One hundred and three patients affected by OSCC and 103 volunteers without OSCC were genotyped for 5-HTTLPR. Both groups were matched for age, sex and tobacco use. The chi-squared test was used for statistical analysis (α=0.05). There was no statistically significant difference in 5-HTTLPR genotypes between case and control group (p= 0.408). In conclusion, the present investigation demonstrated that serotonin transporter polymorphisms are not implicated in the OSSC development.

O mixoma odontogênico (MO) é um tumor odontogênico benigno de origem mesenquimal caracterizado pela presença de células fusiformes ou estreladas dispostas em abundante matriz extracelular mucóide. A metilação do DNA é caracterizada pela adição de grupos metil em citosinas constituintes de ilhas CpG na região promotora do gene. A metilação pode diminuir a expressão de genes supressores de tumor e contribuir para o desenvolvimento de lesões neoplásicas. O objetivo deste trabalho foi avaliar o padrão de metilação nos genes P16 (CDKN2A), P21 (CDKN1A), P27 (CDKN1B), P53 (TP53), RB1 nos MO e na polpa dental. A metilação foi avaliada pela reação em cadeia da polimerase específica para a metilação. A transcrição dos genes foi estudada em alguns casos pela reação da transcriptase reversa (PCR quantitativa). Uma maior frequência de amostras não metiladas para os genes P27, P53 e RB1 foi observada nos MO quando comparados à polpa dental. Os MO expressaram RNAm de todos os genes avaliados. Considerando todas as amostras juntas, a expressão de Rb foi maior em amostras não metiladas comparadas as amostras parcialmente metiladas. Esta investigação mostrou a hipometilação dos genes P27, P53 e RB1 nos MO. Adicionalmente, a metilação nos genes supressores de tumor é um evento frequente em polpa dental normal.

Odontogenic myxoma (OM) is an ectomesenchymal benign odontogenic tumor characterized by spindle or stellate-shaped cells embedded in an abundant myxoid or mucoid extracellular matrix. DNA methylation is characterized by the addition of methyl groups in cytosines within CpG islands in the promoter gene. DNA methylation can decrease the expression of tumor suppressor genes and contribute to the development of neoplastic lesions. The aim of study was to evaluate the methylation pattern of the tumor suppressor genes P16 (CDKN2A), P21 (CDKN1A), P27 (CDKN1B), P53 (TP53) and RB1 in OM and dental pulp. Methylation was evaluated using methylation-specific polymerase chain reaction (PCR). The transcription was studied in some cases by using reverse transcription quantitative PCR. A higher frequency of unmethylated P27, P53, and RB1 samples was observed in the OM when compared with the dental pulp. OM expressed mRNA of all the genes evaluated. Considering all the samples together, the expression of Rb was higher in the unmethylated samples compared with the partially methylated samples. This investigation revealed hypomethylation of the genes P27, P53, and RB1 in OM. In addition, methylation of tumor suppressor genes was found to be an usual event in normal dental pulp.

Apesar da importância que a clonalidade das lesões tem para o entendimento da patogênese e progressão dos tumores, ainda não foi feita essa investigação em lesões de células gigantes dos maxilares. O objetivo desse trabalho foi analisar a natureza clonal de lesões periféricas de células gigantes (LPCG) e de lesões centrais de células gigantes (LCCG). Foram analisadas nesse estudo 6 amostras de LPCG e 5 amostras de LCCG, sendo todas elas provenientes de pacientes do sexo feminino. Para essa investigação foi utilizado o método baseado na região polimórfica do exon um do gene humano para oreceptor de andrógeno (HUMARA). Três das 5 amostras de LCCG e 3 das 6 amostras de LPCG exibiram um padrão monoclonal. Nossos resultados demonstram que algumas lesões de células gigantes dos maxilares apresentam uma natureza monoclonal indicando que essas lesões podem ter um mecanismo genético comum de desenvolvimento. Outros estudos são necessários para uma maior compreensão dos mecanismos moleculares envolvidos na patogênese dessas lesões.

Despite the importance of clonality to understand the pathogenesis and progression of tumors, it has not been investigated yet in giant cell lesions of the jaws. The aim of this study was to analyze the clonality of peripheral giant cell lesions (PGCL) and central giant cell lesions (CGCL) of the jaws. Six samples of PGCL and 5 samples of CGCL were analyzed in this study using the polymorphic human androgen receptor locus (HUMARA) assay. Three out of the 5 samples of the CGCL and 3 out of 6 samples of PGCL exhibited a monoclonal pattern. Our findings demonstrate that some giant cell lesions of the jaws are clonal, which indicate that these lesions may have a common genetic mechanism of development. Further studies are necessary to better elucidate the molecular mechanisms involved in the pathogenesis of such lesions.

O objetivo do estudo é investigar o impacto do transplante de células-tronco hematopoiéticas (TCTH) na colonização da mucosa bucal pela Helicobacter pylori através do "nested-PCR". Quarenta e seis pacientes submetidos ao TCTH e 46 indivíduos saudáveis foram incluídos no estudo. Raspados de mucosa bucal foram realizados nos pacientes do grupo de estudo e grupo controle. Os dados médicos dos pacientes foram revisados e as seguintes informações foram coletadas: gênero e idade do paciente, gênero do doador, doença primária, fonte de células-tronco (medula óssea ou células-tronco sanguíneas), número de leucócitos, neutrófilos e plaquetas, doença do enxerto contra o hospedeiro crônica (DECHc) de glândulas salivares. Os resultados demonstram aumento na freqüência de H. pylori na mucosa bucal de pacientes submetidos ao TCTH comparado com grupo controle (r = 0.002). A presença da H. pylori na mucosa bucal não teve relação com a severidade da DECHc. As medianas de número de plaquetas/mm³, leucócitos/mm³ e neutrófilos/mm³ no grupo de pacientes TCTH positivos para H. pylori não foram estatisticamente diferentes das medianas dos pacientes negativos. Concluindo, o presente estudo mostra um aumento da freqüência da H. pylori na mucosa bucal de pacientes submetidos ao TCTH quando comparada com a de um grupo de voluntários não transplantados saudáveis.

This study was designed to investigate the impact of haematopoietic stem cell transplantation (HSCT) on Helicobacter pylori colonization of the oral mucosa by nested polymerase chain reaction (nested-PCR). Forty six consecutive patients submitted to HSCT and 46 healthy volunteers were included in the study. Oral swabs were taken from the oral mucosa of the patients and control group. The medical records of the patients were reviewed and the following information was retrieved: gender and age of the patient, donor gender, primary disease, stem cell source (bone marrow or blood stem cells), leukocyte, neutrophil and platelet counts, and chronic graft versus host disease (cGVHD) of salivary glands. The results demonstrated an increased frequency of H. pylori in the oral mucosa of HSCT patients compared to controls (rho = 0.002). The presence of H. pylori in the oral mucosa was not related to the severity of cGVHD. The median counts of platelet/mm³, leukocytes/mm³ and neutrophils/mm³ in the group of HSCT patients positive for H. pylori were not statistically different from those of the patients negative for it. In conclusion, the present study shows increased frequency of H. pylori in the oral mucosa of HSCT patients compared to non-transplanted healthy volunteers.