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1.
Braz. dent. sci ; 24(3): 1-13, 2021. tab, ilus
Article in English | BBO - Dentistry , LILACS | ID: biblio-1281321

ABSTRACT

Objective: Evaluate the effect of four preparation designs, two ceramic materials, and two occlusion contact types on the stress distribution of ceramic veneer in upper central incisor. Material and methods: 3D-models were performed in the modeling software containing enamel, dentin, pulp, periodontal ligament and a base of polyurethane resin. The designs were modeled and exported to the computer aided engineering software to perform the static structural analysis. For the mesh, a total of 155429 tetrahedron elements and 271683 nodes were used, after a 10% convergence test. Two materials, lithium disilicate and feldspathic ceramics, were simulated. A static load of 100 N on 45º was applied on the incisal and middle thirds of the palatal tooth region, guided by the occlusal plane. The base was constrained in all directions. The Maximum Principal Stress was the failure criteria chosen for the analysis. Results:The Finite Element Analysis showed that the most conservative designs presented less stress concentration on the ceramic veneer. However, the highest tensile stress concentrations were observed on lithium disilicate veneer with extend design, on the middle third. The type of occlusal contact presented different stress patterns among the preparation designs; the incisal contact showed higher stress concentration compared to middle third contact regardless the ceramic material. Conclusion: To perform a ceramic veneer in upper central incisor, the feldspathic ceramic presented promising results and should be recommended when the extended design was done. Regarding contact types, the incisal contact is more prone to failure regardless the ceramic and preparation design. (AU).


Objetivo: Avaliar o efeito de quatro desenhos de preparo, dois materiais cerâmicos e dois tipos de contato oclusais na distribuição de tensão de laminado cerâmico em incisivo central superior. Material e métodos: Modelos 3D foram realizados em software de modelagem contendo esmalte, dentina, polpa, simulador de ligamento periodontal e uma base de resina de poliuretano. Os desenhos foram modelados e exportados para o software de engenharia para realizar análise estatística estrutural. Para a malha, foram usados um total de 155429 elementos tetraedros e 271683 nós, após teste de convergência de 10%. Dois materiais, dissilicato de lítio e cerâmica feldspática, foram simulados. Uma carga estática de 100N em 45º foi aplicada no terço incisal e médio na região palatina do dente, guiada pelo plano oclusal e a base foi restringida em todas as direções. A tensão de tração foi o critério de falha escolhido para a análise. Resultados: A análise de elementos finitos mostrou que os desenhos mais conservadores apresentaram menor concentração de tensão no laminado cerâmico. Contudo, as maiores concentrações de tensões foram observadas no laminado de dissilicato de lítio com preparo estendido no terço médio. O tipo de contato oclusal apresentou diferentes padrões de tensões entre os diferentes desenhos, o contato incisal mostrou maior concentração de tensão em relação ao contato do terço médio independentemente do material cerâmico Conclusão: Para a confecção de laminado cerâmico em incisivo central superior, a cerâmica feldspática apresentou resultados promissores e é recomendada quando for feito preparo estendido. Em relação aos tipos de contato, o contato incisal é mais sujeito a falhas independentemente da cerâmica e desenho do preparo. (AU)


Subject(s)
Ceramics , Finite Element Analysis , Dental Veneers
2.
Oral Health Prev Dent ; 18(1): 549-554, 2020.
Article in English | MEDLINE | ID: mdl-32515427

ABSTRACT

PURPOSE: Resin infiltration may be a barrier for bleaching gels. The aim of this study was to compare dental bleaching effectiveness using low-concentration gels on heavily or mildly stained teeth that were or were not treated with resin infiltration agents. MATERIALS AND METHODS: Forty bovine enamel surfaces were submitted to demineralisation, after which two staining protocols were performed. Twenty specimens were immersed in a staining broth for 24 h (Lab 1) or 7 days (Lab 2). Ten specimens of each group received resin infiltrant application following the manufacturer's recommendation. All specimens were bleached using 15% carbamide peroxide gel for 14 days (8 h daily). Colour measurement was performed using a reflectance spectrophotometer at three time points: baseline, after staining, and after bleaching. Data (CIEDE00) were analysed using Student's t-test (p < 0.05). RESULTS: No statistically significant differences were observed in Lab 1 (p = 0.560). For Lab 2, statistically significant differences were detected (p = 0.031). Once bleaching was achieved to some degree (Lab 2), the resin infiltrant may have behaved as a semipermeable barrier to the carbamide peroxide gels. CONCLUSION: Bleaching treatment was effective on mildly pigmented tooth surfaces. On the other hand, in comparison to the control group, the heavily pigmented surfaces bleached less in the presence of the resin infiltrant, possibly due to the lack of free radicals penetrating into the substrate.


Subject(s)
Tooth Bleaching Agents , Tooth Bleaching , Tooth Discoloration , Animals , Carbamide Peroxide , Cattle , Dental Enamel , Drug Combinations , Humans , Resins, Plant
3.
Clin Oral Investig ; 24(3): 1321-1331, 2020 Mar.
Article in English | MEDLINE | ID: mdl-31297659

ABSTRACT

OBJECTIVES: The purpose of this study was to evaluate the 2-year success of resin composite restorations in non-carious cervical lesions (NCCLs) using the direct or semi-direct techniques. MATERIALS AND METHODS: Thirty volunteers presenting with at least two NCCLs were included. Each participant received one restoration using the direct technique and the other using the semi-direct technique, totaling 60 restorations. Time for completing the treatment was computed. Assessments at baseline, 7 days, and 6, 12, and 24 months were performed using the modified United States Public Health Service criteria. Descriptive analysis was reported as a percentage of successful treatments. For inferential analysis, the Student t test was used to evaluate the differences between extension, depth, and time. The chi-square/Fisher tests were used to compare treatment success after each period (α = 0.05). The results were evaluated by using the Kaplan-Meier survival analysis. RESULTS: Differences were detected regarding mean ± standard deviation time, in which direct and semi-direct procedures were accomplished in 21.8 (± 14.5) and 35.3 (± 19.9) min, respectively. Of the 60 restorations placed, 7 failed in the direct group while 8 failed in the semi-direct group up to 2 years. No differences were detected between restorative protocols. The cumulative survival was 88.5% and 88.4% for the direct technique and semi-direct techniques after 24 months, respectively. CONCLUSION: The tested restorative protocols present similar results for NCCLs within the studied periods. CLINICAL RELEVANCE: The semi-direct technique exhibited clinical performance similar to direct technique for NCCL, demonstrating an alternative for restorations of these lesions.


Subject(s)
Composite Resins , Dental Restoration, Permanent/methods , Tooth Cervix/pathology , Aged , Dental Marginal Adaptation , Female , Humans , Male , Middle Aged
4.
Braz. dent. sci ; 21(4): 451-460, 2018. ilus
Article in English | LILACS, BBO - Dentistry | ID: biblio-966311

ABSTRACT

Objective: To evaluate the visual perception of surface gloss of resin composite under different illuminants by different observers. Material and methods: twelve cylindrical specimens (6mm x 1mm) were fabricated using a nanofilled resin composite (Z350, A2E shade) in order to compare different observers and to determine the limit of perceptibility of surface gloss. Bovine tooth specimen with similar dimensions was obtained for the comparison of different illuminants. Polishing of resin specimens was performed resulting in 6 groups, presenting surface gloss values at 10, 25, 40, 55, 70, and 85 GU (gloss units), measured by glossmeter (NOVOCURVE). Fifteen individuals were selected: 5 lay-person, 5 undergraduate students, and 5 dental professionals. Participants observed the specimens in a light booth (Gti lightbox) under three different illuminants, and rated the possible combinations between resin specimens or with the bovine enamel specimen (85GU). Data obtained were analyzed by PROBIT non-linear regression analysis (α=0.05). Results: Differences were observed among types of illuminants (p=0.042) and ΔGU (p=0.004), with no interaction between factors (p=0.139). The fluorescent light presented lower surface gloss perceptibility values in relation to incandescent light. There was no influence by type of observers (p=0.598). The surface gloss perception limit was 17.6 GU under the presented tested conditions. Conclusion: the illuminant type influenced perception of gloss, with lower percentage of perceptibility for fluorescent light, while such perceptibility was not influence by different observers. (AU)


Objetivo: Avaliar a percepção visual e táctil do brilho superficial da resina composta sob diferentes iluminantes e por diferentes observadores. Material e métodos: foram utilizados doze espécimes cilindricos (6mm x 1mm) fabricados em resina composta nanoparticulada (Z350, 3M ESPE- cor A2E) para comparar diferentes observadores e determinar o limite de perceptibilidade do brilho superficial. Um espécime em dente bovino com dimensões similares foi obtido para a comparação de diferentes iluminantes. O polimento do espécime de resina foi realizado, resultando em 6 grupos (n=2), apresentando valores de brilho superficial em 10, 25, 40, 55, 70 e 85 UB (unidades de brilho), medido por um medidor de brilho (NOVOCURVE ­ Rhopoiny TM, East Sussex, Inglaterra). Foram selecionados quinze indivíduos : 5 leigos, 5 alunos de graduação e 5 profissionais de odontologia. Os participantes observaram espécimes em uma cabine de luz (Gti lightbox, New Jersey, USA), sob três iluminantes diferentes, e avaliaram as possíveis combinações entre espécimes de resina ou com espécime de esmalte bovino (85 UB). Resultados: os dados obtidos foram analisados por análise de regressão não-linear PROBIT (5%). As diferenças foram observadas entre os tipos de iluminantes (p= 0,042) e Δ UB (p= 0,004), sem interação entre os fatores (p= 0,139). A luz fluorescente apresentou valores de percepção de brilho da superfície inferior em relação á luz incandescente. Não houve influência pelo tipo de observadores (p= 0,598). O limite de percepção do brilho superficial foi de 17,6 UB sob as condições testadas apresentadas. Conclusão: o tipo de iluminante influenciou na percepção do brilho, com menor porcentagem de perceptibilidade para luz fluorescente (p=0,042), enquanto que a perceptibilidade não foi influenciada pelos diferentes observadores. (AU)


Subject(s)
Observer Variation , Composite Resins , Dental Polishing
5.
Braz. dent. sci ; 20(3): 58-64, 2017. ilus, tab, graf
Article in English | LILACS, BBO - Dentistry | ID: biblio-868089

ABSTRACT

Objetivo: O objetivo deste estudo foi avaliar a quantidade de elementos químicos (Ca, O, C, P, Fe e Mg) e a microdureza superficial da dentina esclerótica escurecida em dentes humanos. Material e Métodos: O estudo foi aprovado pelo Comitê de Ética local e dez dentes extraídos (cinco hígidos e cinco apresentando dentina esclerosada) foram utilizados. Os dentes foram seccionados no sentido mésiodistal e cada metade foi utilizada para cada teste. A quantidade de elementos químicos (%w) foi determinada pela espectroscopia de raio-x por dispersão em energia (EDS) em três áreas dentinárias diferentes (superficial, média ou profunda). Estas mesmas áreas tiveram a microdureza superficial Knoop determinada. Os dados foram analisados por ANOVA dois fatores e teste de comparações múltiplas, com nível de significância de 5%. Resultados: Nenhuma diferença quanto à microdureza foi detectada entre a dentina hígida e esclerótica (p = 0,743) e nem em relação às profundidades (p = 0,837). Menor quantidade de Ca (p = 0,024) e maior quantidade de C (p = 0,015) foram encontradas na dentina esclerótica superficial. O aumento do conteúdo de Mg (p < 0,001) foi detectado na dentina hígida. Conclusão: Pode-se concluir que a dentina esclerótica apresenta microdureza superficial similar à dentina hígida. Os elementos químicos estudados apresentaram-se igualmente para os dois tipos de dentina, exceto para o Mg, o qual estava em maior quantidade na dentina hígida. O cálcio e o fósforo apresentaram quantidades reduzidas na dentina esclerótica superficial.(AU)


Objective: The aim of this study was to assess the amount of chemical elements (Ca, O, C, P, Fe, and Mg) and the cross-section hardness of sclerotic darkened dentin in human teeth. Material and Methods: The study was approved by the local IRB and ten extracted teeth (five sound and five presenting sclerotic darkened dentin) were used. Tooth was sectioned mesiodistally and each half was used for each test. Amount of chemical elements (%w) was determined by energy dispersive X-ray spectroscopy (EDS) in three different dentin areas (shallow, medium, or deep sound or sclerotic dentin). Knoop microhardness was determined at the same EDS areas. Data were analyzed by two-way ANOVA and multiple comparison tests, with significance level at 5%. Results: No difference on microhardness was detected between sound and sclerotic dentin (p = 0.743) and also among dentin depths (p = 0.837). Lower Ca (p = 0.024) and higher C (p = 0.015) amounts were found at superficial sclerotic dentin. Increased Mg content (p < 0.001) was detected in sound dentin. Conclusion: It was concluded darkened sclerotic dentin presents similar cross-section microhardness to sound dentin. The assessed chemical elements were similarly present in sound or sclerotic dentin, except for Mg, which was present higher concentration in sound dentin. Ca and P were lower in superficial sclerotic dentin (AU)


Subject(s)
Dentin , Hardness , Minerals , Tooth Remineralization
6.
São José dos Campos; s.n; 2014. 103 p. ilus, tab, graf.
Thesis in Portuguese | BBO - Dentistry | ID: biblio-867594

ABSTRACT

O objetivo do estudo foi verificar a distribuição de tensões nas facetascerâmicas confeccionadas com dois tipos de material: feldspato edissilicato de lítio em quatro diferentes tipos de preparos limitados aoesmalte dental: (1) vestibular; (2) vestibular com redução incisal; (3)vestibular com cobertura incisal e (4) estendido, em duas situaçõesoclusais: carga aplicada no terço incisal e no terço médio palatino, obtidaspor meio de análise por elementos finitos. Os modelos tridimensionaisforam realizados no software CAD Rhinoceros 4.0® utilizando um arquivostl (estereolitografia) de um incisivo central superior, com dimensõesmédias encontradas na literatura, onde foram simuladas as condiçõesutilizadas para realização de um teste experimental. Os modelos foramcompostos por esmalte, dentina, polpa, poliéter (para simular ligamentoperiodontal), cerâmica e base e foram submetidos a cargas de 100 N sobangulação de 45º em relação ao plano oclusal. O pré-processamento epós-processamento foram realizados pelo programa de elementos finitosAnsys® v.13.0. Os resultados foram apresentados em gráficos de tensãomáxima principal, com seus respectivos valores numéricos representadosem escala de cores. A análise de elementos finitos mostrou que osdesenhos mais conservadores apresentaram uma melhor distribuição de tensão nos laminados cerâmicos de dissilicato de lítio em comparação àcerâmica feldspática, no entanto, a mais alta concentração de tensão foiencontrada nas facetas desse mesmo material no grupo estendidoquando submetido à carga no terço médio palatino. O tipo do contatooclusal causou diferente distribuição de tensão entre os diferentes tiposde preparos, sendo que, o contato incisal promoveu uma maiorconcentração de tensão nas facetas realizadas com ambos materiaisexceto no preparo estendido confeccionado com a porcelana dedissilicato de lítio


The purpose of this study was to verify the stress distribution in theceramic veneers made with two types of porcelain: feldspathic and lithiumdisilicate in four different design types limited to dental enamel:(1) buccalpreparation, (2) buccal preparation with incisal reduction, (3) buccalpreparation with coverage incisal and (4) extended preparation in twodifferent occlusal situations: load on the incisal third and the middle thirdpalatine, through mathematical finite element method. Three-dimensionalCAD models were performed in CAD Rhinoceros 4.0® using a stl file of amaxillary central incisor with average dimensions found in the literature,where conditions used for conducting an experimental test. The modelswere composed of enamel, dentin, pulp, polyether (to simulate theperiodontal ligament), and ceramic base and underwent loads of 100 Nunder an angle of 45 degrees to the occlusal plane in the incisal andmiddle thirds of the palatal tooth region. Preprocessing and postprocessing by ANSYS® version 13.0 finite element program wereperformed. The results were presented in plots by principal maximumstress with their respective numerical values represented by the colorscale. The finite element analysis showed that for the most conservativedesigns present a better stress distribution on veneers of lithium disilicate, nevertheless, the higher tensile stresses concentrations were found on veneers of same material for group subjected to palatal chamfer design when subjected to load in the middle third palate. The type of occlusalcontact contact caused different distribution of tension among the different types of preparations design, and the incisal contact promoted higherstress concentration in both facets except the extended preparationperformed with porcelain lithium disilicate


Subject(s)
Humans , Ceramics , Dental Veneers , Finite Element Analysis
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