Prolonged Inhibition of Streptococcus mutans Growth and Biofilm Formation by Sustained Release of Chlorhexidine from Varnish Coated Dental Abutments: An in Vitro Study.

Background: It has been confirmed that bacterial biofilm covering dental implants is the main microbial source causing preimplant infectious and inflammatory diseases. The purpose of this study was to evaluate the antibacterial/antibiofilm effect of chlorhexidine, incorporated into a sustained-release varnish of chlorhexidine (SRV-CHX) coating, on dental abutments. Materials and Methods: Three kinds of dental abutments were used: a high-performance semi-crystalline engineering thermoplastic polyetheretherketone (PEAK) healing abutment, a titanium healing abutment, and a titanium permanent abutment. These abutments were coated with SRV-CHX or SRV-placebo and exposed daily to fresh cultures of Streptococcus mutans. The effect of SRV-CHX on S. mutans growth on agar plates was studied by measuring the zone of inhibition (ZOI) around each tested abutment every day for a period of 36 days. Biofilm formation on the SRV-CHX/placebo-coated abutments was detected using confocal laser scanning microscopy (CLSM) and high-resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), and monitored by crystal violet (CV) staining. Results: SRV-CHX-coated abutments 2 and 3 were able to inhibit S. mutans growth for 34 days, while abutment 1 inhibited growth for 32 days. Abutment-associated biofilm formation was notably inhibited by SRV-CHX coating after 13 days of incubation with S. mutans. Finally, the biofilm formed around SRV-CHX-coated abutments was completely inhibited up to 12 days of abutment exposure to S. mutans. Conclusion: Coating of dental abutments with SRV-CHX demonstrated long-term effective inhibition of S. mutans growth and biofilm formation on the abutment surface.

Hypoxia-driven intratumor heterogeneity and immune evasion.

While it is widely accepted that high intratumoral heterogeneity confers serious challenges in the emerging resistance and the subsequent effective therapeutic targeting of cancer, the underlying biology of intratumoral heterogeneity remains elusive. In particular, it remains to be fully elucidated how microenvironmental factors shape genetic and non-genetic heterogeneity, which in turn determine the course of tumor evolution and clinical progression. In this context, hypoxia, a hallmark of most growing cancers, characterized by decreased O2 partial pressure is a key player of the tumor microenvironment. Despite extensive data indicating that hypoxia promotes cellular metabolic adaptation, immune suppression and various steps of tumor progression via hypoxia regulated gene transcription, much less is known about the role of hypoxia in mediating therapy resistance as a driver of tumor evolution through genetic and non-genetic mechanisms. In this review, we will discuss recent evidence supporting a prominent role of hypoxia as a driver of tumor heterogeneity and highlight the multifaceted manner by which this in turn could impact cancer evolution, reprogramming and immune escape. Finally, we will discuss how detailed knowledge of the hypoxic footprint may open up new therapeutic avenues for the management of cancer.

Assessment of alveolar bone level and furcation involvement in periodontal diseases using dental cone-beam computed tomography (CBCT): a systematic review / Avaliação do nível ósseo alveolar e envolvimento da furca em doenças periodontais usando a Tomografia computadorizada de feixe cônico odontológica: uma revisão sistemática

The advent of CBCT has contributed significantly to dental imaging. In the field of periodontics, CBCT provides a multi-planar view to assess the alveolar bone in three dimensions. This helps the dentist to make measurements at any location that could significantly improve periodontal diagnosis. Objective: The aim of this systematic review is to evaluate the accuracy of using CBCT in the assessment of alveolar bone level and furcation involvement in periodontal diseases. Material and Methods: PubMed, LILACS and Google Scholar databases were searched for literature related to the application of CBCT in periodontal diseases. Keywords used for the search were CBCT, furcation involvement, measurement and their synonyms. Results: Fifteen full-text English language research papers were eligible for the systematic review using the PRISMA guidelines. Conclusion: From the results of the systematic review it can be concluded that conebeam computed tomography imaging technique offers significantly reliable images of the furcation involvement and height of the alveolar bone. (AU)

O advento da Tomografia computadorizada de feixe cônico (TCFC) contribuiu significativamente para a imageologia. No campo da periodontia, a TCFC fornece uma visão multiplano para avaliar o osso alveolar em três dimensões. Isso ajuda o dentista a fazer medições em qualquer local que possa melhorar significativamente o diagnóstico periodontal. Objetivo: O objetivo desta revisão sistemática foi avaliar a precisão do uso da TCFC na avaliação do nível ósseo alveolar e do envolvimento da furca em doenças periodontais. Material e Métodos: As bases de dados PubMed, LILACS e Google Scholar foram pesquisadas na literatura relacionada à aplicação da TCFC em doenças periodontais. As palavras-chave utilizadas para a pesquisa foram TCFC, envolvimento da furca, mensuração e seus sinônimos. Resultados: Quinze trabalhos de pesquisa em inglês com texto completo foram elegíveis para a revisão sistemática usando as diretrizes do PRISMA. Conclusão: A partir dos resultados da revisão sistemática, pode-se concluir que a técnica de imagem por tomografia computadorizada de feixe cônico oferece imagens significativamente confiáveis do envolvimento da furca e da altura do osso alveolar.(AU)