RESUMEN
This study aims at comparing conventional and nickel-free metal bracket surface characteristics with elemental composition by scanning electron microscopy (SEM), using energy dispersive spectroscopy (EDS). The sample consisted of 40 lower incisor brackets divided into four groups: ABZ = conventional brackets, Kirium Abzil 3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10); NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-free brackets, Roth Max Morelli® (n = 10). Qualitative evaluation of the bracket surface was performed using SEM, whereby surface features were described and compared. The elemental composition was analyzed by EDS. According to surface analysis, groups ABZ and RL showed a homogeneous surface, with better finishing, whereas the surfaces in groups NF and RM were rougher. The chemical components with the highest percentage were Fe, Cr and C. Groups NF and MR showed no nickel in their composition. In conclusion, the bracket surface of the ABZ and RL groups was more homogeneous, with grooves and pores, whereas the surfaces in groups NF and RM showed numerous flaws, cracks, pores and grooves. The chemical composition analysis confirmed that the nickel-free brackets had no Ni in their composition, as confirmed by the manufacturer's specifications, and were therefore safe to use in patients with a medical history of allergy to this metal.
Asunto(s)
Metales/química , Níquel/química , Soportes Ortodóncicos , Aleaciones/química , Análisis de Varianza , Corrosión , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Valores de Referencia , Espectrometría por Rayos X , Estadísticas no Paramétricas , Propiedades de SuperficieRESUMEN
This study aims at comparing conventional and nickel-free metal bracket surface characteristics with elemental composition by scanning electron microscopy (SEM), using energy dispersive spectroscopy (EDS). The sample consisted of 40 lower incisor brackets divided into four groups: ABZ = conventional brackets, Kirium Abzil 3M® (n = 10); RL = conventional brackets, Roth Light Morelli® (n = 10); NF = nickel-free brackets, Nickel-Free Morelli® (n = 10); and RM = nickel-free brackets, Roth Max Morelli® (n = 10). Qualitative evaluation of the bracket surface was performed using SEM, whereby surface features were described and compared. The elemental composition was analyzed by EDS. According to surface analysis,groups ABZ and RL showed a homogeneous surface, with better finishing, whereas the surfaces in groups NF and RM were rougher. The chemical components with the highest percentage were Fe, Cr and C. Groups NF and MR showed no nickel in their composition. In conclusion, the bracket surface of the ABZ and RL groups was more homogeneous, with grooves and pores, whereas the surfaces in groups NF and RM showed numerous flaws, cracks, pores and grooves. The chemical composition analysis confirmed that the nickel-free brackets had no Ni in their composition, as confirmed by the manufacturer’s specifications, and were therefore safe to use in patients with a medical history of allergy to this metal.
Asunto(s)
Metales/química , Níquel/química , Soportes Ortodóncicos , Análisis de Varianza , Aleaciones/química , Corrosión , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Valores de Referencia , Espectrometría por Rayos X , Estadísticas no Paramétricas , Propiedades de SuperficieRESUMEN
O consumo de álcool é um dos fatores de risco para o desenvolvimento do câncer bucal; entretanto, os mecanismos envolvidos no dano gerado pelo álcool são parcialmente compreendidos. Determinadas concentrações de álcool causam aumento da permeabilidade da mucosa bucal, potencializando a penetração de carcinógenos. Além disso,é responsável por um aumento na proliferação epitelial, bem como pela modificação do seu processo de maturação.Outras alterações, como redução da capacidade de reparo de DNA, distúrbios do sistema imune e do estado nutricional podem contribuir na sua relação com o desenvolvimento do câncer bucal. O metabolismo do álcool aumenta a produção de radicais livres e diminui os mecanismos antioxidantes, levando ao estresse oxidativo. O polimorfismo genético das enzimas de degradação do álcool pode ser responsável pela diferença na sensibilidade individual. Algumas isoformas dessas enzimas permitem o acúmulo de metabólitos tóxicos como o acetadeído,que pode causar dano ao DNA ou a outras estruturas celulares. A partir de uma revisão de literatura, esse trabalho tem como objetivo estabelecer uma relação entre os diferentes mecanismos da ação do álcool e a carcinogênese na cavidade oral.
Asunto(s)
Humanos , Masculino , Femenino , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/etiología , Consumo de Bebidas Alcohólicas/efectos adversos , Mucosa Bucal , Neoplasias de la Boca/diagnóstico , Neoplasias de la Boca/etiología , Factores de RiesgoRESUMEN
The aim of this study was to investigate cell proliferation rate and certain morphological features of mouse epithelium as aging progresses. Tongue biopsies were performed on female mice (Mus domesticus domesticus) at 2, 8, 14 and 20 months of age as indicative of adolescence, adulthood, early senescence and senescence, respectively. Histological sections of tongue were stained with hematoxylin-eosin and subjected to silver staining for active nucleolar organizer region counting. Cell proliferation rate and epithelial thickness analysis were carried out. Analysis of variance detected no differences between the groups in terms of numbers of silver-stained dots associated with nucleolar proteins. There was an increase in mean epithelial thickness in adult animals, followed by a gradual reduction until senescence. Mean keratin thickness presented an increase at 8 and 20 months of age. This difference is probably related to puberty, growth or dietary habits. Aging has no influence on oral epithelial proliferation rate in mice. A gradual reduction in epithelial thickness is a feature of aging in mammals. A conspicuous increase in the keratin layer was observed in senescence as an adaptative response to the reduction in epithelial thickness. These results suggest that aging affects the oral epithelium maturation process through a mechanism that is not related to cell proliferation.