The aim of this study was to identify the immunoexpression of methallothionein in oral squamous cell carcinoma as well as to address the correlation with clinical features, histological grade and patient survival. Samples were collected from 93 patients with tongue squamous cell carcinoma who presented for follow-up. Immunohistochemical expression of methallothionein in all groups was performed. The scoring system has previously been published by Tsurutani in 2005, which is based on intensity and distribution of staining. We used Kappa index to evaluate the degree of observers' agreement under metallothionein immunostaining and histological grade. Associations between methallothionein expression and clinical parameters (age, gender, smoking, tumor size, lymph node metastasis and disease stage) were examined for statistical significance using the chi-squared test. The overall survival rates were estimated by the Kaplan-Meier method and the relationship between protein expression and survival was compared using the log-rank test (p < 0.05). Our results showed no statistically significant association between methallothionein immunostaining and the selected clinicopathological variables. Immunohistochemistry results showed positive nuclear immunostaining for metallothionein in 62,37% (58/93) and negative for metallothionein 37,63% (35/93). The degree of examiners agreement by Kappa varied from substantial to perfect and both metallothionein immunostaining and histological grade were explored. The present study suggests that positive methallothionein expression found in tongue squamous cell carcinoma may not help to predict survival in the analyzed samples, as well as no relation between the protein and histological grade and clinical features was observed. In conclusion, the present study suggests that metallothionein is not associated with tongue squamous cell carcinoma clinicopathological characteristics and aggressiveness.

RESUMOO Bruxismo do Sono (BS) é uma ocorrência muito comum na infância, que compromete não somente a integridade da arcada dentária, como também a qualidade de vida da criança. Mesmo não havendo uma única justificativa para sua etiologia, existem pesquisas atualizadas que apontaram variadas causas que motivam crianças a desenvolverem o BS nesta fase da vida. Este estudo teve por objetivo uma pesquisa sistemática da literatura acerca de trabalhos publicados nos últimos 10 anos que objetivaram investigar as causas associadas ao BS em crianças de 0 a 12 anos. A busca foi realizada nas bases LILACS, MEDLINE, PubMed, IBECS, SciELO, ScienceDirect e Web Of Science utilizando as palavras-chaves "sleep bruxism", "etiology of sleep bruxism children", "children bruxism", "cause" e "diagnosis", todas cruzadas nos sistemas de busca utilizando os operadores booleanos AND, OR ou NOT. A partir da pesquisa inicial, foram aplicados filtros, através da análise Título, Resumo e Texto Completo, obtendo-se ao final 15 artigos das bases SciELO, ScienceDirect e Web Of Science, com base nos critérios de inclusão e exclusão pré-estabelecidos. As causas mais frequentes associadas ao BS em

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