Exploiting Nanomaterials for Optical Coherence Tomography and Photoacoustic Imaging in Nanodentistry.

There is already a societal awareness of the growing impact of nanoscience and nanotechnology, with nanomaterials (with at least one dimension less than 100 nm) now incorporated in items as diverse as mobile phones, clothes or dentifrices. In the healthcare area, nanoparticles of biocompatible materials have already been used for cancer treatment or bioimaging enhancement. Nanotechnology in dentistry, or nanodentistry, has already found some developments in dental nanomaterials for caries management, restorative dentistry and orthodontic adhesives. In this review, we present state-of-the-art scientific development in nanodentistry with an emphasis on two imaging techniques exploiting nanomaterials: optical coherence tomography (OCT) and photoacoustic imaging (PAI). Examples will be given using OCT with nanomaterials to enhance the acquired imaging, acting as optical clearing agents for OCT. A novel application of gold nanoparticles and nanorods for imaging enhancement of incipient occlusal caries using OCT will be described. Additionally, we will highlight how the OCT technique can be properly managed to provide imaging with spatial resolution down to 10's-100's nm resolution. For PAI, we will describe how new nanoparticles, namely TiN, prepared by femtosecond laser ablation, can be used in nanodentistry and will show photoacoustic microscopy and tomography images for such exogenous agents.

Photoacoustic imaging of occlusal incipient caries in the visible and near-infrared range.

PURPOSE: This study aimed to demonstrate the presence of dental caries through a photoacoustic imaging system with visible and near-infrared wavelengths, highlighting the differences between the 2 spectral regions. The depth at which carious tissue could be detected was also verified. MATERIALS AND METHODS: Fifteen permanent molars were selected and classified as being sound or having incipient or advanced caries by visual inspection, radiography, and optical coherence tomography analysis prior to photoacoustic scanning. A photoacoustic imaging system operating with a nanosecond pulsed laser as the light excitation source at either 532 nm or 1064 nm and an acoustic transducer at 5 MHz was developed, characterized, and used. En-face and lateral (depth) photoacoustic signals were detected. RESULTS: The results confirmed the potential of the photoacoustic method to detect caries. At both wavelengths, photoacoustic imaging effectively detected incipient and advanced caries. The reconstructed photoacoustic images confirmed that a higher intensity of the photoacoustic signal could be observed in regions with lesions, while sound surfaces showed much less photoacoustic signal. Photoacoustic signals at depths up to 4 mm at both 532 nm and 1064 nm were measured. CONCLUSION: The results presented here are promising and corroborate that photoacoustic imaging can be applied as a diagnostic tool in caries research. New studies should focus on developing a clinical model of photoacoustic imaging applications in dentistry, including soft tissues. The use of inexpensive light-emitting diodes together with a miniaturized detector will make photoacoustic imaging systems more flexible, user-friendly, and technologically viable.

Impacto do Tratamento Antineoplásico na Microbiota da Cavidade Oral e Orofaríngea de Pacientes Acometidos pelo Câncer de Cabeça e Pescoço: Revisão Sistemática / Impact of Antineoplastic Treatment on Oral Cavity and Oropharyngeal Microbiota of Head and Neck Cancer Patients: Systematic Review / Impacto del Tratamiento Antineoplástico en la Microbiota Oral y Orofaríngea de Pacientes Afectados por el Cáncer de Cabeza y Cuello: Revisión Sistemática

Introdução: As cavidades oral e orofaríngea apresentam uma grande diversidade de micro-organismos que se encontram normalmente em homeostase com outros micro-organismos e o próprio hospedeiro, contudo, pacientes com câncer de cabeça e pescoço submetidos ao tratamento oncológico podem desencadear modificações fisiológicas nos seus organismos, assim como impactos na sua microbiota residente. Objetivo: Revisar sistematicamente os estudos sobre o impacto provocado pelo tratamento antineoplásico sobre a microbiota oral e orofaríngea em pacientes com câncer de cabeça e pescoço. Método: Revisão sistemática, realizada entre abril e junho de 2020. Busca nas bases de dados Biblioteca Virtual em Saúde, Google Acadêmico, PubMed e ScienceDirect. Utilizaram-se os descritores "head and neck neoplasms", "mouth neoplasms" e "microbiota" em inglês; e "neoplasias de cabeça e pescoço", "neoplasias bucais" e "microbiota" em português. Foram selecionados artigos originais e disponíveis na íntegra, publicados na última década (2010 a 2020), nos idiomas português e inglês. Resultados: Foram incluídos oito artigos nesta revisão. Assim, a maioria dos estudos apresentou alterações na quantidade de micro-organismos residentes ou invasão de bactérias exógenas nos pacientes submetidos ao tratamento antineoplásico; o descontrole da homeostase da microbiota desencadeou processos cariogênicos e inflamatórios na mucosa. Conclusão: As alterações no microbioma da cavidade oral e orofaríngea advindas do tratamento antineoplásico podem ser fatores de predisposição a efeitos adversos no indivíduo, como desenvolvimento de cárie e mucosite oral

Introduction: A great diversity of microorganisms are found in the oral and oropharyngeal cavities, which are normally in homeostasis with other microorganisms and the host itself. Patients with head and neck cancer undergoing cancer treatment may trigger physiological changes in their bodies and impact in the resident microbiota. Objective: Systematically review studies on the impact of antineoplastic treatment on oral and oropharyngeal microbiota in patients with head and neck cancer. Method: Systematic review carried out between April and June 2020. Articles were searched in the Virtual Health Library, Google Scholar, PubMed and ScienceDirect databases in English, utilizing the descriptors "head and neck neoplasms", "mouth neoplasms" and "microbiota" and "neoplasias de cabeça e pescoço", "neoplasias bucais" and "microbiota" in Portuguese. Original articles available in full, published in the last decade (2010 to 2020), in Portuguese and English were selected. Results: 8 articles were included in this review. Most of studies have shown quantitative changes in resident microorganisms or invasion of exogenous bacteria in patients in antineoplastic treatment; uncontrolled microbiota homeostasis triggered cariogenic and inflammatory processes in the mucosa. Conclusion: Changes in the microbiome of the oral cavity and oropharyngeal resulting from antineoplastic treatment may be predisposing factors for adverse effects as the development of caries and oral mucositis

Introducción: Las cavidades bucal y orofaríngea presentan una gran diversidad de microorganismos que normalmente se encuentran en homeostasis con otros microorganismos y su propio hospedador, sin embargo, los pacientes con cáncer de cabeza y cuello sometidos a tratamiento contra el cáncer pueden desencadenar cambios fisiológicos en tu cuerpo, así como también impactos en su microbiota residente. Objetivo: Revisar sistemáticamente los estudios sobre el impacto del tratamiento antineoplásico en la microbiota oral y orofaríngea en pacientes con cáncer de cabeza y cuello. Método: Revisión sistemática realizada entre abril y junio de 2020. Se buscaron artículos en las bases de datos de la Biblioteca Virtual en Salud, Google Scholar, PubMed y ScienceDirect. Se utilizaron los descriptores "head and neck neoplasms", "mouth neoplasms" and "microbiota" en inglés y "neoplasias de cabeça e pescoço", "neoplasias bucais" e "microbiota" en portugués. Incluyeron artículos originales y disponibles en su totalidad, publicados en la última década (2010 a 2020), en portugués e inglés. Resultados: En esta revisión se incluyeron ocho artículos. Así, la mayoría de los estudios han mostrado cambios en el número de microorganismos residentes o invasión de bacterias exógenas en pacientes sometidos a tratamiento antineoplásico, la homeostasis de la microbiota sin controle desencadena procesos cariogénicos e inflamatorios en la mucoso. Conclusión: Los cambios en el microbioma de la cavidad oral y orofaríngea por el tratamiento antineoplásico pueden ser factores predisponentes a los efectos adversos en el individuo, como el desarrollo de caries y mucositis oral

Nanopartículas de prata em bases de próteses de PMMA para controle de atividade microbiana / Silver nanoparticles in PMMA prosthesis bases to control microbial activity

Objetivo:Avaliar in vitro a atividade de Staphylococcus aureus e Candida albicans em bases de próteses convencionais à base de polimetilmetacrilato de metila com nanopartículas de prata incorporadas a sua composição. Métodos: Foi realizado um estudo experimental laboratorial com resinas acrílicas autopolimerizáveis comercialmente disponíveis, Vipi Flash/VIPI e JET/Clássico. Foram confeccionados 80 corpos de prova, divididos em 16 grupos (n = 5), referentes ao tipo de resina, tratamento (incorporação e imersão na solução de nanopartículas de prata) e microrganismo inoculado. As nanopartículas foram sintetizadas com ácido polimetacrílico, nitrato de prata e irradiadas com luz ultravioleta de baixa potência (~8W) por 6 horas, e as suas concentrações idealizadas pelo método de microdiluição em placas para determinação da concentração mínima inibitória frente aos microrganismos selecionados. Verificou-se ação bactericida e fungicida com concentração inicial de 25% e após fator de diluição 12,5%. Resultados: Houve dificuldade de incorporação das nanopartículas na resina acrílica, que pode decorrer da alteração da proporção 3:1 recomendada pelo fabricante ou pela redução ou inativação da ação da nanopartícula de prata pela interação com o polimetilmetacrilato. VIPI com inclusão de nanopartícula obteve menor aderência de biofilme de Candida albicans. Conclusão:A nanopartícula de prata mostrou-se eficaz na sua ação de controle de Candida albicans e Staphylococcus aureus no método de imersão, entretanto, a sua ação antimicrobiana foi comprometida após inclusão nas resinas acrílicas.

Aim:To perform an in vitro evaluation of the activity of Staphylococcus aureus and Candida albicansin conventional prosthesis bases, based on methyl polymethylmethacrylate with silver nanoparticles incorporated into the composition. Methods: An experimental laboratory study was carried out using commercially available self-curing acrylic resins, Vipi Flash/VIPI and JET/Clássico. Eighty specimens were manufactured and divided into 16 groups (n = 5), referent to the resin brand, treatment (incorporation and immersion in the silver nanoparticle solution), and inoculated microorganism. The nanoparticles were synthesized with polymethacrylic acid and silver nitrate, and were irradiated with a low power (~ 8W) ultraviolet light for 6 hours. Their concentrations were idealized by the method of microplate dilution to determine the minimum inhibitory concentration when compared to the selected microorganisms. Bactericidal and fungicidal activities were identified with an initial concentration of 25% and a subsequent dilution factor of 12.5%. Results:It was difficult to incorporate the AgNPs into the acrylic resin, which may well have resulted from the change from the 3:1 proportion recommended by the manufacturer or by reducing or inactivating the action of the silver nanoparticle by interaction with polymethylmethacrylate. VIPI with the inclusion of nanoparticles obtained a lesser Candida albicans biofilm adherence. Conclusion: Silver nanoparticles were effective in controlling Candida albicans and Staphylococcus aureus in the immersion method; however, the antimicrobial activity was compromised after inclusion in acrylic resins.

Remineralizing Potential of Nano-Silver-Fluoride for Tooth Enamel: An Optical Coherence Tomography Analysis

Objective: To evaluate the use of nanosilver fluoride in the enamel remineralization process through optical coherence tomography. Material and Methods: All samples were submitted to demineralization process by pH cycling during 14 days and randomly distributed into three groups (n = 11): Nanosilver Fluoride (NSF), Sodium fluoride (NaF), and negative control. Optical coherence tomography images were acquired at three different moments: initial stage (T0), post caries formation (T1), and post pH cycling (T2). The integrity of the enamel surface and the measurement of the volume loss for the tissue after pH cycling in comparison to initial images were obtained from optical coherence tomography images. Results: After analyzing the exponential decay of A-scans from each group, it was possible to identify differences in light propagation among samples. In T1 it is not possible to visualize the dentin-enamel junction, probably due to the higher back scattering of the demineralized enamel, which does not allow light to reach the dentin. The decay curves obtained from NaF and nanosilver fluoride groups showed similar behavior, while the negative group showed lower extinction coefficient. Conclusion: Nanosilver fluoride showed the best effect against caries compared to conventional fluoride treatments.

Propriedades e aspectos biológicos do agregado trióxido mineral: revisão da literatura / Properties and biological aspects of mineral trioxide aggregate: literature review

O material obturador ideal deve apresentar características específicas, como biocompatibilidade, selamento marginal adequado, capacidade de permitir ou induzir o reparo ósseo e facilidade de manipulação e inserção. O agregado trióxido mineral (MTA) foi desenvolvido como um material para obturação retrógrada com melhores propriedades químicas, físicas e biológicas do que os materiais existentes na época, como amálgama, material restaurador intermediário (IRM) e SuperEBA. Atualmente, o MTA é usado como material de preenchimento radicular no selamento apical, no reparo de perfurações e como agente de capeamento pulpar, além de ser usado como material de obturação retrógrada. O objetivo deste artigo foi realizar uma revisão da literatura acerca do agregado trióxido mineral, comparando-o com os principais cimentos endodônticos e materiais obturadores retrógrados disponíveis no mercado para a retrobturação do sistema de canais radiculares, analisando suas propriedades e características biológicas. Concluiu-se que o MTA é um material obturador retrógrado bastante satisfatório do ponto de vista químico-físico-biológico, especialmente por sua biocompatibilidade e seu potencial de ação osteocondutora, osteoindutora e cementocondutora.

The ideal root canal sealer should present specific characteristics, as biological compatibility, appropriate marginal sealing, ability to allow or induce bone repair, and ease of manipulation and insertion. Mineral trioxide aggregate (MTA) was developed such a retro-sealer with better chemistry, physics and biological properties than materials that exist at the time, as amalgam, intermediate restorative material (IRM), and SuperEBA. Actually, MTA is used such a canal filling material to seal root apical, at drilling repair, and as a pulp capping agent; in addition, it is used as a filling retrograde material. The purpose of this study was a literature review about mineral trioxide aggregate, comparing it to the main endodontic cements and retro-sealer materials available at market for root canal filling retrograde filling, analyzing its properties and biological characteristics. It was concluded MTA is a quite satisfactory retro-sealer material, in terms of its chemical-physical-biological properties, especially due to its biocompatibility, and potential actions do conduce and induce the repair of bone and cementum.

Avaliação das normas de biossegurança nas clínicas odontológicas da UFPE / Evaluation of biosecutrity norms in UFPE dental clinics

O objetivo deste trabalho foi observar o cumprimento das normas de biossegurança e os cuidados com os riscos ocupacionais pelos alunos que atenderam nas clínicas de Odontologia Preventiva, Odontopediatria, Dentística, Endodontia e nos procedimentos cirúrgicos nas clínicas de Periodontia e Cirurgia da Faculdade de Odontologia da Universidade Federal de Pernambuco. Este trabalho consistiu em um estudo observacional, no qual foram anotados em formulário o cumprimento ou não das normas de biossegurança e cuidados com os riscos ocupacionais pelos alunos durante o atendimento, no período de outubro/2006 a maio/2007. Os alunos foram observados em 09 clínicas, perfazendo no total de 488 fichas observadas. Procurou-se contemplar as clínicas em igual proporção de observações. Os resultados apontaram ausência de manilúvio, inadequações no uso dos EPI para alunos e pacientes, falta de local exclusivo para lavagem de instrumental e deficiências ergonômicas durante a prática clínica. Concluiu-se que é necessária a divulgação mais intensa de políticas públicas que orientem a utilização das normas de biossegurança entre os alunos da instituição, assim como reavaliação e mudanças na infra-estrutura das clínicas e conteúdos dos treinamentos em aula oferecidos aos alunos do curso de Odontologia da UFPE, no intuito de melhor conscientiza-los e prevenir a ocorrência de acidentes ocupacionais.

The purpose of this study was to observe the biosecurity norms execution, as well as the cares with the occupational risky by students who attended at Preventive Dentistry 2, Pediatric Dentistry 1 and 2, Dentistics 2 and 3, Endodontics 2 and 3 clinics, and surgical procedures in Periodontics and Surgery 1 clinics, of Faculdade de Odontologia at Universidade Federal de Pernambuco. This work consisted an observational study, in which were annotated in form the compliance or not of biosecurity norms and caution with occupational risks by the students during the service, in the period from October/2006 to May/2007. Students were observed at 09 clinics, for a total of 488 observed forms. It looked to comtemplate the clinics in equal observations proportion. Results pointed to the washing hands absence, inadequate use of individual protection equipments for students and patients, exclusive place to wash instruments lack and ergonomic deficiencies during the clinical practice. It was concluded it is necessary largest public policies divulgation to guide the biosecurity norms use among institution students, as well as revaluation and changes in clinical infrastructure and class training contents given to UFPE Dentistry students, in order to better awareness them and prevent occupational accidents occurrence.