Polarization and scanning electron microscopy of bovine dentine structure after using different endodontic auxiliary chemical substances

Orientador: Alexandre Augusto ZaiaDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: O objetivo desse trabalho foi avaliar a ocorrência de alterações na estrutura e organização do colágeno presente na matriz orgânica da parede dentinária do canal radicular de incisivos bovinos bem como, avaliar a topografia da matriz inorgânica desta estrutura após irrigação com hipoclorito de sódio 5,25%, EDTA 17% e clorexidina gel 2%. Foram utilizados 60 dentes bovinos divididos aleatoriamente em seis grupos com 10 dentes cada: G1 - Hipoclorito de sódio (NaOCl) 5,25% e EDTA 17%; G2 - Clorexidina gel 2%; G3 - NaOCl 5,25%; G4 - EDTA 17%; G5 - Clorexidina gel 2% e EDTA 17%; G6 - Solução de cloreto de sódio 0,9% (Controle). Uma análise paralela foi realizada em 10 dentes onde nenhum tipo de procedimento foi realizado, sendo possível a obtenção dos parâmetros da birrefringência característica de incisivos bovinos sem instrumentação. As amostras experimentais foram submetidas à instrumentação e irrigação com as diferentes substâncias químicas auxiliares e em seguida, segmentadas em dois fragmentos. Um fragmento foi processado histologicamente utilizando o corante pricrosirius e em seguida, seu retardo óptico foi mensurado por meio de microscopia de polarização. O outro segmento foi preparado e avaliado por meio de microscopia eletrônica de varredura. Os resultados das mensurações dos retardos ópticos foram submetidos à análise estatística por meio do teste de Dunnet. Os resultados demonstraram que os grupos tratados com a clorexidina gel 2% e EDTA 17%, associados ou não, não obtiveram diferença estatisticamente significante em relação ao grupo controle. Nos grupos tratados com NaOCl 5,25%, associado ou não ao EDTA 17%, as médias dos retardos ópticos foram estatisticamente diferentes ao grupo controle. Concluindo que o NaOCl 5,25% provoca alterações na organização macromolecular do colágeno presente na matriz orgânica da dentina radicular de dentes bovinos. A análise realizada por meio da MEV demonstrou alterações estruturais na matriz inorgânica em todos os grupos em que o EDTA 17% foi utilizadoAbstract: The aim of this study was to evaluate the change in collagen structure and organization present in the organic matrix of the dentine wall of the root canals of bovine inferior incisors as well as the topography of the inorganic matrix after irrigation with 5.25% sodium hypochlorite, 17% EDTA and 2% chlorexidine gel. Sixty bovine incisors were randomly divided into six groups of 10: G1 - 5.25% Sodium Hypochlorite (NaOCl) and 17% EDTA; G2 - 2% Chlorexidine gel; G3 - 5.25% NaOCl; G4 - 17% EDTA; G5 - 2% Chlorexidine gel and 17% EDTA; G6 (Control) - 0.9% Sodium chloride. A parallel analysis was performed with 10 teeth which had not been submitted to any treatment. Hence, it was possible to obtain parameters for the birefringence characteristic of non-instrumented inferior bovine incisors. Experimental samples were submitted to instrumentation and irrigation with different auxiliary chemical substances and then segmented in two. One fragment was histologically processed using picrosirius pigment. Its optical retardations were measured through polarization microscopy. The second fragment was prepared to be evaluated through scanning electron microscopy. The optic retardation measurement data were submitted to statistical analysis using Dunnet?s test. Results revealed that the groups that associated or not 2% chlorexidine gel and 17% EDTA were not statistically different in relation to the control group. For the groups which 5.25% NaOCl was used, associated or not to 17% EDTA, the average optic retardations were statistically different to the control group. Therefore, 5.25% sodium hypochlorite proved to cause alterations to the molecular organization of collagen present in the organic matrix of root dentine of bovine teeth. Scanning electron microscopy showed structural alterations of the inorganic matrix of all groups tested with 17% EDTAMestradoEndodontiaMestre em Clínica Odontológic

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Conduta clínica e terapêutica de abscessos periapicais agudos

Em razão da íntima relação anatômica entre a polpa e os tecidos da região periapical, os processos inflamatórios da polpa dental quando não tratados em tempo, tendem a se difundir para os tecidos do periodonto apical, originando as chamadas lesões periapicais. Essas lesões surgem, quase invariavelmente, da difusão dos microrganismos que colonizam a polpa necrosada para os tecidos do ligamento periodontal apical. Dentre as alterações periapicais, encontram-se os abscessos periapicais, que são reações inflamatórias agudas caracterizadas por coleções purulentas localizadas, estando implícito o caráter agudo de sua ocorrência do ponto de vista microscópico e clínico. Os abscessos periapicais estão freqüentemente associados com destruição relativamente rápida do osso alveolar e têm capacidade de disseminar e alcançar seios paranasais e outros espaços da cabeça e pescoço. O diagnóstico de um abscesso periapical consiste na história clínica e avaliação dos sinais e sintomas. O tratamento baseia-se na drenagem cirúrgica e debridamento do sistema de canais radiculares. Quando necessário associada à drenagem, uma adequada terapêutica medicamentosa sistêmica pode ser administrada. A escolha da técnica é determinada pela severidade de sinais e sintomas e da necessidade de se estabelecer uma via adequada de drenagem.Thanks to the intimate relationship between pulp and the tissues of the periapical region, the inflammatory processes of the dental pulp, when not treated immediately, tend to spread to the tissues of the apical periodontium, originating the so called periapical lesions, which appear invariably from the diffusion of microorganisms which colonize the necrotic pulp to the tissues of the apical periodontal ligaments. Among the periapical alterations are periapical abscesses that are acute inflammatory reactions characterized by localized collections of pus, which makes implicit the acute character of the episode in a microscopic and clinical point of view. The periapical abscesses are frequently associated with a relatively rapid destruction of the alveolar bone and the capacity of disseminating and reaching the paranasal sinuses and other spaces of the head and neck. The diagnosis of a periapical abscess is difficult and is limited to clinical history. This way, the treatment is based on surgical drainage and decontamination of the system of root canals. When necessary, associated to drainage, an adequate systemic therapeutic medication may be prescribed. The choice for a technique is determined by the severity of signs and symptoms, as well as the necessity to establish a correct drainage pathway

Effects of reducing agents and endodontics auxiliary chemical solutions on biomechanical properties of root dentin

Orientador: Alexandre Augusto ZaiaTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de PiracicabaResumo: Dentre os protocolos de irrigação mais utilizados mundialmente, a associação do hipoclorito de sódio (NaOCl) e o EDTA merece destaque. Entretanto, estes agentes químicos podem causar efeitos deletérios nas propriedades químicas e físicas da dentina, além da ação oxidativa do NaOCl interferir no comportamento de materiais restauradores. O uso de agentes redutores tem demonstrado minimizar os efeitos deletérios do NaOCl previamente a procedimentos restauradores. No primeiro estudo que compõe esta tese teve-se como objetivo avaliar os efeitos do ácido ascórbico 10% e/ou ascorbato de sódio 10% após a irrigação com NaOCl 5,25%, EDTA 17% ou cloreto de sódio 0,9% no colágeno presente na matriz orgânica da parede dentinária do canal radicular de incisivos bovinos. Foram utilizados oitenta incisivos bovinos aleatoriamente divididos em oito grupos (n=10): G1(Controle): cloreto de sódio 0,9%; G2: NaOCl 5,25% + EDTA 17%; G3: NaOCl 5,25% + EDTA 17% + ácido ascórbico 10%; G4: NaOCl 5,25% + EDTA 17% + ascorbato de sódio 10%; G5: NaOCl 5,25%; G6: EDTA 17%; G7: ácido ascórbico 10%; G8: ascorbato de sódio 10%. Os espécimes foram submetidos à instrumentação e irrigação com as diferentes substâncias químicas auxiliares e em seguida submetidos ao processamento histológico para análise em microscopia de polarização. Os grupos que demonstraram alteração no padrão de birrefringência foram submetidos à análise de absorbância para a confirmação da perda de proteína. Foi possível concluir que o uso do ácido ascórbico 10% e/ou ascorbato de sódio 10% conseguiu restabelecer os valores de retardo óptico antes diminuídos pelo uso de NaOCl 5,25%, associado ou não ao EDTA 17%. Já no segundo estudo, este teve como objetivo avaliar os efeitos do ácido ascórbico 10% e/ou ascorbato de sódio 10% após a irrigação com NaOCl 5,25%, EDTA 17% ou cloreto de sódio 0,9% na microdureza Knoop e resistência flexural da dentina radicular bovina. A distribuição dos grupos foi feita de forma similar ao primeiro estudo. Foram utilizados 80 dentes bovinos para o teste de microdureza Knoop e 120 barras de dentina para o ensaio de flexão de 3-pontos. O NaOCl 5,25% reduziu de forma significativa os valores de microdureza Knoop, chegando a afetar a dureza mesmo em grandes profundidades na dentina radicular bovina. A aplicação de ascorbato de sódio conseguiu revertes os valores previamente reduzidos de microdureza. Ficou comprovado que o NaOCl 5,25% afeta de forma negativa a resistência flexural, mas ao se fazer uso do ácido ascórbico após o protocolo de irrigação com NaOCl e EDTA, os valores de resistência flexural foram restabelecidos, chegando mesmo a equiparar-se ao grupo controleAbstract: Among the auxiliary chemical substances used in Endodontics during chemical-mechanical preparation, sodium hypochlorite (NaOCl) and EDTA have been the most widely recommended. However, irrigant solutions used in endodontic therapy might yield changes in the chemical and physical properties of dentin. Besides, these reagents compromised the bond strengths of some adhesives on root dentin. The aim of the first study was to evaluate the effect of 10% acid ascorbic or 10% sodium ascorbate on organic matrix collagen of bovine dentin root canal walls after irrigation with 5.25% sodium hypochlorite, 17% EDTA or 0.9% sodium chloride. Eighty bovine incisors were randomly divided into eight groups (n=10) according to: G1(Control): 0.9% Sodium Chloride; G2: 5.25% NaOCl + 17% EDTA; G3: 5.25% NaOCl + 17% EDTA + 10% ascorbic acid; G4: 5,25% NaOCl + 17% EDTA + 10% sodium ascorbate; G5: 5.25% NaOCl; G6: 17% EDTA; G7: 10% ascorbic acid; G8: 10% sodium ascorbate. Teeth were chemomechanically prepared and submitted to histological processing to be analyzed under polarized light microscopy. Absorbance assay was also performed to confirm the loss of collagen. It is possible to conclude that groups treated with 5.25% NaOCl (G2 and G5) presented a significantly different birefringence pattern compared with the control group (p<0.05).The birefringence values reduced could be reversed by the application of either 10% ascorbic acid or 10% sodium ascorbate after 5.25% NaOCl and 17% EDTA irrigation. The absorbance assay of G2 and G5 confirmed the loss of collagen (p<0.05). The second study aimed to evaluate the effect of 10% ascorbic acid or 10% sodium ascorbate application after 5.25% NaOCl, 17% EDTA or 0.9% sodium chloride irrigation in the Knoop microhardness and flexural strength on root dentin. Eighty bovine incisors were randomly divided into eight groups (n=10): G1 (Control): 0.9% Sodium Chloride; G2: 5.25% NaOCl + 17% EDTA; G3: 5.25% NaOCl + 17% EDTA + 10% ascorbic acid; G4: 5.25% NaOCl + 17% EDTA + 10% sodium ascorbate; G5: 5.25% NaOCl; G6: 17% EDTA; G7: 10% ascorbic acid; G8: 10% sodium ascorbate. Teeth were chemomechanically prepared and submitted to Knoop microhardness. Standardized plano-parallel dentin bars were prepared and randomly divided into the same eight groups (n=15) cited above. The dentin bars were then loaded to failure in a three-point bend test. Root canal irrigation with 5.25% NaOCl reduced the microhardness of dentin in all distances tested. The microhardness values increased in all distances when sodium ascorbate was used after 5.25% NaOCl and 17% EDTA irrigation. By exposing the dentin bars to 5.25% NaOCl, whether it was associated or not to 17% EDTA, the flexural strength decreased. However, values increased when 10% ascorbic acid or 10% sodium ascorbate were used after 5.25% NaOCl and 17% EDTA irrigationDoutoradoEndodontiaDoutor em Clínica Odontológic

Effect of the smear layer on the filling of artificial lateral canals and microleakage

Aim: To evaluate the influence of the smear layer on the filling and prevention of microleakage in artificial lateral canals after use of different irrigating solutions. Methods: Two lateral canals were produced in 44 human dental roots with drills of 0.1 mm in diameter. The roots were divided in 4 groups according to the irrigation protocol: GI - 0.9% saline solution (control); GII - 2.5% sodium hypochlorite + 17% EDTA; GIII - 2% chlorhexidine gel + 17% EDTA; GIV - 2% chlorhexidine solution + 17% EDTA. Four roots were used as negative (n=2) and positive (n=2) controls. Lateral condensation technique and AH Plus were used to fill the root canals. Digital buccolingual radiographs were exposed and after the sealer had set, the roots were immersed in Indian ink dye and then cleared in methyl salicylate. The extent of filling and microleakage were measured and the values analyzed statistically. Results: No difference was found in the percentage of filling and microleakage among the groups, regardless of the location of the artificial lateral canals and the irrigation protocol used. Twenty percent of lateral canals produced no radiographic images, but their filling was confirmed using the clearing technique. Conclusions: The presence or absence of the smear layer did not affect the filling ability and the prevention of microleakage in artificial lateral canals

Effect of the smear layer on the filling of artificial lateral canals and microleakage

evaluate the influence of the smear layer on the filling and prevention of microleakage in artificial lateral canals after use of different irrigating solutions. Methods: Two lateral canals were produced in 44 human dental roots with drills of 0.1 mm in diameter. The roots were divided in 4 groups according to the irrigation protocol: GI - 0.9% saline solution (control); GII - 2.5% sodium hypochlorite + 17% EDTA; GIII - 2% chlorhexidine gel + 17% EDTA; GIV - 2% chlorhexidine solution + 17% EDTA. Four roots were used as negative (n=2) and positive (n=2) controls. Lateral condensation technique and AH Plus were used to fill the root canals. Digital buccolingual radiographs were exposed and after the sealer had set, the roots were immersed in Indian ink dye and then cleared in methyl salicylate. The extent of filling and microleakage were measured and the values analyzed statistically. Results: No difference was found in the percentage of filling and microleakage among the groups, regardless of the location of the artificial lateral canals and the irrigation protocol used. Twenty percent of lateral canals produced no radiographic images, but their filling was confirmed using the clearing technique. Conclusions: The presence or absence of the smear layer did not affect the filling ability and the prevention of microleakage in artificial lateral canals

Resumos concluídos - Saúde Coletiva

Resumos concluídos - Saúde Coletiv