RESUMO
The incidences of Citrus leprosis virus C (CiLV-C) and Orchid fleck dichorhavirus Citrus strain (OFV-citrus) were determined in field populations of Brevipalpus mites from 15 citrus-producing states in Mexico. Mites were collected from orange, grapefruit, mandarin, lime, and sweet lime orchards. Brevipalpus yothersi (Baker) (Trombidiformes: Tenuipalpidae) was the most abundant species followed by Brevipalpus californicus (Banks) (Trombidiformes: Tenuipalpidae), which confirmed previous reports. The viruses CiLV-C and OFV-citrus were found in both mite species. The incidence of CiLV-C, OFV-citrus and both viruses simultaneously (CiLV-C and OFV-citrus) was 17.2, 10.3, and 3.4% (n = 116) for B. yothersi, and 12.5, 20.8, and 4.1% (n = 24) for B. californicus, respectively. No significant difference was found when the incidence of these viruses was compared between both mite species. The importance of our results in relation to the epidemiology of leprosis is discussed.
Assuntos
Citrus , Ácaros , Animais , Incidência , México , Doenças das Plantas , Cimento de Fosfato de ZincoRESUMO
Abstract Objective: To assess the tensile bond strength of prefabricated metal posts cemented with different luting agents. Material and Methods: Fifty single-rooted endodontically treated human teeth had their crowns cut, mounted into acrylic-resin blocks and then an 8mm depth post space were prepared. Prefabricated cylindrical metal posts were cemented using different luting agents: a zinc phosphate cement (SS White), a conventional glass ionomer cement (Vidrion C), two resin-modified glass ionomer cements (Vitremer and RelyX Luting 2) and a resin cement (RelyX ARC). Samples were stored in distilled water for seven days and then submitted to a tensile bond strength test until complete dislocation of the post. One-way analysis of variance and Tukey test for pairwise multiple comparisons were used to evaluate differences between luting agents. Results: Tensile bond strength was 563.88±203.41 N for zinc phosphate cement, 336.86 ± 137.64 N for Vidrion C, 515.24 ± 239.48 N for Vitremer, 828.47±433.99 N for RelyX Luting 2 and 1262.51 ± 356.29 for RelyX ARC. The Relyx ARC presented the highest tensile bond strength regard the luting agent tested (p< 0.05). Conclusion: RelyX ARC presented the higher tensile bond strength compared to the other luting agents evaluated.
Assuntos
Resistência à Tração , Cimentos de Resina , Cimentos Dentários , Cimentos de Ionômeros de Vidro , Cimento de Fosfato de Zinco , Brasil/epidemiologia , Análise de Variância , Estatísticas não Paramétricas , Dente não Vital/diagnóstico , Pinos DentáriosRESUMO
Abstract Objective: To assess the cytotoxicity, surface morphology, elemental compositions and chemical characterization of two commonly used luting cement. Material and Methods: The two luting types of cement used were Elite Cement® and Hy-Bond Resiglass®. Freshly mixed (n=6) and set form (n=6) of each cement was placed in medium to obtain extracts. The extract from each sample was exposed to L929 mouse fibroblasts (1x104cells/well). Alamar Blue Assay assessed cell viability. Surface morphology and elemental composition were evaluated using scanning electron microscopy and energy dispersive spectroscopy. The chemical characterization was performed by Fourier Transform Infrared Spectroscopy. One-way ANOVA and post-hoc Tukey analysis were conducted to assess results. Results: Hy-Bond Resiglass® was the more cytotoxic of the two types of cement in both freshly mixed (68.10 +5.16; p<0.05) and set state (87.58 +4.86; p<0.05), compared to Elite Cement® both freshly mixed (77.01 +5.45; p<0.05) and set state (89.39 +5.66; p<0.05). Scanning electron microscopy revealed a more irregular and porous structure in Hy-Bond Resiglass® compared to Elite Cement®. Similarly, intense peaks of aluminium, tungsten and fluorine were observed in energy dispersive spectroscopy in Hy-Bond Resiglass. Conclusion: All these three elements (aluminium, tungsten and fluorine) have cytotoxic potential. The Fourier transform infrared spectroscopy revealed the presence of hydroxyethyl methacrylate in Hy-Bond Resiglass®, which has a cytotoxic potential.
Assuntos
Animais , Camundongos , Ratos , Cimento de Fosfato de Zinco , Técnicas In Vitro/métodos , Cimentos Dentários , Fibroblastos , Paquistão , Ratos , Análise Espectral , Tungstênio , Microscopia Eletrônica de Varredura , Análise de Variância , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Introduction: Endodontically treated teeth are more susceptible to root fracture than vital teeth. In order to reduce the risk of fracture, the use of intra-radicular posts and crowns is indicated. However, their own fracture resistance remains unclear. Objective: To analyze the behavior of metal-ceramic crown copings cemented to two types of intra-radicular posts under tensile stress. Material and method: Sixteen metal-ceramic crown copings cemented with zinc phosphate cement to cast metal posts and cores (group 1, n = 8) or with self-adhesive resin cement to glass-fiber posts rebased with composite resin (group 2, n = 8) were subjected to tensile testing after endodontic treatment and standardized preparation. Failure occurred when the crown coping and/or post-core assembly fractured and/or detached. Result: In group 1, after the application of a mean tensile load of 46.83 N, 7 crown copings and metal cores separated as a whole, while in 1 specimen the coping detached from the metal core. In group 2, a mean tensile load of 127.68 N resulted in glass-fiber post fracture, and in 1 case the entire crown-post-core assembly was detached. Tensile strength differed significantly between the two groups (p = 0.0085). Conclusion: Our findings suggest that metal-ceramic crown copings cemented with self-adhesive resin cement show strong adhesion to composite resin cores associated with glass-fiber posts, thus providing a safe alternative to the use of cast metal posts and cores.
Introdução: Os dentes tratados endodonticamente são mais suscetíveis à fratura radicular do que os dentes vitais. Para reduzir o risco de fratura, indica-se o uso de coroas e retentores intrarradiculares. No entanto, ainda não está clara a resistência dessas estruturas a fraturas. Objetivo: Analisar o comportamento de copings de coroa metalocerâmica cimentados com dois tipos de retentores intrarradiculares sob tensão de tração. Material e método: Dezesseis copings de coroa metalocerâmica cimentados com cimento de fosfato de zinco para núcleos e pinos de metal fundido (grupo 1, n= 8) ou com cimento resinoso autoadesivo para núcleos de resina composta com pinos de fibra de vidro (grupo 2, n= 8) foram submetidos a testes de tração após tratamento endodôntico e preparo padronizado. Houve falha quando o coping da coroa e/ou a estrutura pino-núcleo se quebrou e/ou se soltou. Resultado: No grupo 1, após a aplicação de uma carga de tração média de 46,83 N, 7 copings e núcleos metálicos se separaram completamente, enquanto em 1 espécime o coping se soltou do núcleo metálico. No grupo 2, uma carga de tração média de 127,68 N resultou em fratura do pino de fibra de vidro, e em 1 caso toda a estrutura coroa-pino-núcleo se soltou. A resistência à tração foi significativamente diferente entre os dois grupos ( P= 0,0085). Conclusão: Nossos achados sugerem que copings de coroa metalocerâmica cimentados com cimento resinoso autoadesivo apresentam forte adesão aos núcleos de resina composta associados aos pinos de fibra de vidro, proporcionando uma alternativa segura ao uso de retentores de metal fundido.
Assuntos
Resistência à Tração , Cimento de Fosfato de Zinco , Técnica para Retentor Intrarradicular , Resinas Compostas , Cimentos de Resina , CoroasRESUMO
OBJECTIVE AND BACKGROUND: The correct selections of the cementing agent, the endodontic post material and placement protocol are critical to provide an increased longevity of the teeth that went through endodontic treatment. The irradiation with diode laser before post cementation, can promote an antimicrobial effect. However, there is a lack of information about the effect of 830 nm diode laser on the post bond strength. This study analyzed the effect of dentin root canal irradiation with high-intensity diode laser, at 830 nm, operating in continuous or pulsed mode, on the retention of metal or fiber posts, cemented with self-etching resinous composite (Panavia F) and zinc phosphate cement (ZnPO4). MATERIALS AND METHODS: Human roots were irradiated with diode laser (continuous and pulsed mode). The fiber posts were luted with Panavia F and the metal posts with Panavia F or ZnPO4 cement. Specimens were sectioned into three sections (cervical, middle, and apical). The bond strength was measured by a push-out mechanical analysis. For the statistical analysis, a three-way ANOVA test was applied following a Tukey's pairwise comparison with a significance level of p = 0.05. RESULTS: The irradiated groups presented higher bond strength compared with nonirradiated group (p < 0.05), and the cervical and middle thirds presented higher on bond strength than the apical. The association of metal post and Panavia F presented higher bond strength when irradiated on continuous mode (p < 0.05). Fiber post and Panavia F presented higher bond strength associated to pulsed mode. The mode seems not to make a significant difference. CONCLUSIONS: These results corroborate the importance of the post bond to dentin and root canal debris removal to increase the tooth longevity. It was shown that the dentin to post bond strength were enhanced by the diode laser irradiation either on continuous or pulsed modes.
Assuntos
Colagem Dentária/métodos , Cimentos Dentários/química , Lasers Semicondutores , Técnica para Retentor Intrarradicular , Preparo de Canal Radicular/métodos , Cimentos Dentários/farmacologia , Humanos , Teste de Materiais , Cimentos de Resina/química , Resistência ao Cisalhamento/efeitos dos fármacos , Resistência ao Cisalhamento/efeitos da radiação , Cimento de Fosfato de Zinco/químicaRESUMO
OBJECTIVES: To evaluate the effect of thermal cycling and inner surface treatment with aluminum oxide at different granulations on the tensile strength of Ni-Cr copings cemented with different cementing agents. MATERIALS AND METHODS: Ninety-six metal copings were manufactured and divided into two groups: before and after thermal cycling (n = 48). The copings of both groups were internally treated by sandblasting with aluminum oxide particles of 100 (n = 24) and 320 (n = 24) mesh. The copings were cemented on previously manufactured metal cores using zinc phosphate (n = 8), conventional glass ionomer (CGIC) (n = 8) and resin-modified glass ionomer (RMGIC) (n = 8) cements. The tensile strength before and after thermal cycling was then determined (Newtons). RESULTS: The tensile strength before and after thermal cycling was significantly higher in copings cemented with RMGIC compared to CGIC (p < 0.05) and was similar to that for zinc phosphate (p > 0.05). Thermal cycling and sandblasting of the inner surface of the metal copings with different granulations did not influence retention (p > 0.05). CONCLUSIONS: Zinc phosphate cements and RMGIC showed similar retention. Additionally, the retention of the cements was not influenced by either thermal cycling or the particle size of the aluminum oxide.
Assuntos
Ligas de Cromo/química , Coroas , Cimentos Dentários/química , Corrosão Dentária/métodos , Óxido de Alumínio/química , Cimentação/métodos , Técnica de Fundição Odontológica , Retenção em Prótese Dentária , Análise do Estresse Dentário , Cimentos de Ionômeros de Vidro/química , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Cimentos de Resina/química , Estresse Mecânico , Propriedades de Superfície , Temperatura , Resistência à Tração , Cimento de Fosfato de Zinco/químicaRESUMO
A adaptação marginal é um dos requisitos fundamentais para a longevidade e o sucesso das restaurações. O objetivo desse estudo foi avaliar a influência do desajuste interno associado à diferentes agentes cimentantes na desadaptação marginal de coroas em resina nanocerâmica (Lava Ultimate 3M ESPE) confeccionadas pelo sistema CAD-CAM. A partir do escaneamento de um preparo de coroa total em um pré-molar, foram obtidos 36 modelos em metal. Esses foram divididos em seis grupos de acordo com o desajuste interno (70 µm ou 100 µm) e o cimento (Fosfato de zinco- SS White, Cimento de ionômero de vidro- Ketac Cem 3M/ESPE e Cimento resinoso- Relyx Ultimate 3M/ESPE). Após escaneamento de todos os modelos as coroas foram confeccionadas a partir da fresagem de blocos de resina nanocerâmica (Lava Ultimate 3M/ESPE). Com auxílio de microscópio óptico comparador (40X) foram medidas as desadaptações marginais prévia e posteriormente à cimentação, sendo considerados 8 pontos ao longo do término em todas as faces do corpo de prova. Os valores obtidos após serem submetidos aos testes two-way anova e teste t, demonstraram que as coroas confeccionadas com desajuste interno de 70 µm apresentam desadaptação marginal inferior estatisticamente significante às coroas com desajuste interno de 100 µm. Para o desajuste interno de 70 µm o grupo do cimento fosfato de zinco apresentou o menor gap marginal, sendo que este valor não foi estatisticamente diferente em relação ao grupo do Ketac Cem. Ainda com esse desajuste, o grupo do Ketac Cem não apresentou diferença estatística significante em relação ao grupo do Relyx Ultimate, no entanto esse último promoveu "gap" marginal estatisticamente maior em relação ao grupo do cimento fosfato de zinco. Para o desajuste interno de 100 µm não houve diferença estatisticamente significante no "gap" marginal entre os três cimentos avaliados. O presente estudo demonstrou através da metodologia utilizada, que a menor desadaptação marginal observada nas restaurações de Lava Ultimate, foi proveniente do desajuste interno de 70 µm. Neste grupo os cimentos de fosfato de zinco e de ionômero de vidro demonstraram melhor comportamento comparado ao cimento resinoso, embora o cimento de ionômero de vidro numericamente, mas não estatisticamente tenha apresentado resultado inferior ao do fosfato de zinco
The marginal adaptation is one of the basic requirements for the longevity and success of restorations. The aim of this study was to evaluate the influence of the internal imbalances associated with different luting agents on marginal leakage of crowns Nanoceramic resin ( Lava Ultimate 3M ESPE) made by CAD-CAM system. From the scanning of a full crown preparation in a pre molar were obtained 36 metal models. These were divided into six groups according to the internal imbalances ( 70 or 100 micrometres) and cement (SS White Zinc phosphate, glass ionomer cemet Ketac Cem 3M/ Espe and resinous cement Relyx Ultimate 3M / Espe). After scanning all models crowns were made from milling Nanoceramic resin blocks (Lava Ultimate 3M / Espe). With the aid of optical comparator microscope (40X) were measured prior marginal mismatches and after the cementation, being considered 8 points along the end in all specimen faces. The values were submitted to ANOVA two-way test and t test. Results showded that crowns made with internal imbalances of 70 uM show statistically significant lower marginal leakage to the crows with internal imbalances of 100 micrometres. For the internal imbalances 70 uM zinc phosphate cement group showed the lowest "gap" marginal, and this figure does not show a statistically significant difference compared to Ketac Cem gropu. Even with this misfit, Ketac Cem group showed no statistically significant difference in relation to Relyx Ultimate group, though the latter showed a statistically significant difference compared to zinc phosphate cement group. For the internal imbalances of 100 micrometres there was no statistically significant difference in the "gap" marginal among the three cements. This study demostrated through the methodology used, the lower marginal leakage oberved in Lava Ultimate restorations, was from the inner misfit 70 micrometers...
Assuntos
Desenho Assistido por Computador/estatística & dados numéricos , Cimentos Dentários/uso terapêutico , Adaptação Marginal Dentária/classificação , Restauração Dentária Permanente/tendências , Cimentos de Ionômeros de Vidro/uso terapêutico , Ligas Metalo-Cerâmicas/análise , Cimentos de Resina/uso terapêutico , Resinas Sintéticas/análise , Cimento de Fosfato de Zinco/uso terapêutico , Modelos Dentários/estatística & dados numéricosRESUMO
STATEMENT OF PROBLEM: The constant updating of computer-aided design/computer-aided manufacture (CAD/CAM) systems and the introduction of new systems confirm the need for scientific evidence on internal and marginal adaptation. PURPOSE: The purpose of this in vitro study was to measure and compare the degree of internal and marginal misfits of zirconia single-unit copings made by using 3 different CAD/CAM systems (Ceramill, Lava 3M, and Neoshape). MATERIAL AND METHODS: Twenty-four anatomic prefabricated abutments (Neodent) were used to fabricate zirconia copings in Ceramill (n=8), Lava (n=8), and Neoshape (n=8). All copings were cemented and cut with a precision cutting machine to obtain 5 surfaces (mesial, distal, buccal, palatal, and incisal) and angle regions (internal axiogingival and axioincisal angles). Measurements were obtained from images at a magnification of ×100 and ×200 made with a digital camera attached to an optical microscope and adapted with a measuring device. The data were statistically analyzed with the 2-way ANOVA and Tukey honestly significant difference tests (α=.05). RESULTS: In the internal misfit evaluation, the mean values observed for Ceramill, Lava, and Neoshape were palatal surface 76.5, 65.5, and 77.7 µm (P=.003); angle regions 69.4, 68.6, and 74.5 µm (P=.010); incisal surface 127.7, 97.2, and 182.2 µm (P<.001); and overall mean 72.1, 69.4, and 76.4 µm (P=.003). Significant differences were not found for mesial, distal, or buccal surfaces (P>.05). In the evaluation of marginal misfit (marginal discrepancy and absolute marginal discrepancy), the mean values found were 40.9 and 65.8 µm for Ceramill, 34.2 and 70.0 µm for Lava, and 39.3 and 74.5 µm for Neoshape. No significant differences were found among the 3 systems (P>.05). CONCLUSIONS: Although the Lava system showed a significantly lower value of internal misfit than the Neoshape system, all systems showed clinically acceptable marginal misfit values.
Assuntos
Cerâmica/química , Desenho Assistido por Computador , Coroas , Adaptação Marginal Dentária , Materiais Dentários/química , Ítrio/química , Zircônio/química , Cimentação/métodos , Dente Suporte , Planejamento de Prótese Dentária , Análise do Estresse Dentário/instrumentação , Humanos , Processamento de Imagem Assistida por Computador/métodos , Teste de Materiais , Microscopia/instrumentação , Fotografação/métodos , Estresse Mecânico , Propriedades de Superfície , Titânio/química , Cimento de Fosfato de Zinco/químicaRESUMO
This study aimed to develop and assess a virtual learning object (VLO) on the subject of "luting agents", focusing especially on zinc phosphate cement (ZPC). The methodology and the necessary tools to develop the VLO are described. Dental students (n=29) used this object for 15 days and completed a questionnaire in which they assessed it by using a 4-point scale. Developing the object allowed a virtual simulation of the manipulation of ZPC. The object received positive ratings from the students (4 points, 65.78%; 3 points, 14.85%). The software of choice enabled the combination of all media into one single VLO, which was widely accepted among dental students (AU).
O objetivo do estudo foi desenvolver e avaliar um objeto virtual de aprendizagem (OVA) sobre o tema "agentes de cimentação", com ênfase no cimento de fosfato de zinco (CFZ). A metodologia e as ferramentas necessárias para o desenvolvimento do OVA são descritas. Estudantes de graduação (n=29) utilizaram o objeto durante 15 dias e, para avaliarem-no, responderam a um questionário sobre os aspectos técnicos e pedagógicos do objeto usando uma escala de 4 pontos. O desenvolvimento do objeto permitiu a criação de uma simulação virtual da manipulação do CFZ. O objeto foi bem avaliado pelos estudantes (4 pontos, 65,78%; 3 pontos, 14,85%) estudantes. O software utilizado foi capaz de reunir todas as mídias em um OVA com alta taxa de aprovação entre os estudantes de Odontologia (AU).
Assuntos
Humanos , Masculino , Feminino , Cimento de Fosfato de Zinco , Simulação por Computador , Tecnologia Educacional/instrumentação , Educação a Distância , Estudantes de Odontologia , Software , Interpretação Estatística de DadosRESUMO
Objetivo: comparar ex vivo, por medio de un modelo de filtración bacteriana, la capacidad de sellado de un ionómero vítreo modificado con resinas, de un ionómero vítreo convencional y de un cemento de fosfato de cinc, utilizados para la cementación de coronas coladas (AU). Materiales y métodos: un total de 30 premolares humanos sanos, extraídos, fueron preparados de forma estandarizada para recibir una corona metálica con terminación en chamfer sobre dentina. Se realizaron impresiones, se vaciaron en densita tipo IV, se enceraron y se colaron en aleación de oro tipo III. Luego fueron separadas al azar en tres grupos de 10 (n=10) especímenes cada uno. Las coronas del grupo 1 fueron cementadas con Rely-X Luting Plus (3M/ESPE); y las del grupo 2, con Ketac-Cem (3m/ESPE); y las del grupo 3 (control), con el cemento de fosfato de cinc Harvard Cement (Harvard Debtal International GmbH, Hoppengarten, Alemania). Todos los especímenes fueron termociclados. Posteriormente, la superficie metálica oclusal fue reducida 1 mm hasta exponer la dentina, y las muestras se esterilizaron en autoclave. El proceso de filtración se realizó por medio de un sistema de doble cámara con medio de cultivo. El medio de la cámara superior se inoculó con E. faecalis y el sistema fue incubado durante 60 días. En la cámara inferior, la filtración bacteriana se controló diariamente. Los datos registrados fueron analizados por medio de las pruebas de Kaplan-Meyer y de Fischer, con un nivel de significación de P<0,05. Resultados: el tiempo de supervivencia para Rely-X Luting Plus no pudo ser estimado, ya que fue superior a los 60 días, tiempo máximo de duración de la experiencia. Para Ketac-Cem fue de 60 días, con un intervalo de confianza (95 por ciento) de 29,6-90,4. Y para Harvard Cement fue de 40 días, con un intervalo de confianza de 32,6-47,4. Las diferencias entre los grupos fueron estadísticamente significativas. Conclusión: Rely-X Plus demostró una capacidad de sellado superior.
Assuntos
Coroas , Cimentação/instrumentação , Cimentos Dentários/química , Infiltração Dentária/prevenção & controle , Meios de Cultura , Cimento de Fosfato de Zinco/química , Cimentos de Ionômeros de Vidro/química , Cimentos de Resina/química , Enterococcus faecalis/isolamento & purificação , Teste de Materiais , Interpretação Estatística de Dados , Técnica de Fundição Odontológica/métodosRESUMO
PURPOSE: Occlusal reduction is considered a fundamental step for providing adequate and uniform space for the ceramic prosthesis; however, a flat occlusal surface is usually found. The prosthesis design influences the resistance to deformation and the stress state within the ceramic. This finite element (FE) study analyzes the influence of changing the substructure design on the stress distribution of a metal-ceramic crown in a premolar tooth with three types of occlusal reduction. MATERIALS AND METHODS: Each part of three-dimensional metal ceramic complete crown models was designed according to the space provided by different levels of occlusal reduction and the same external morphology of the tooth. Three models were designed: (1) correct occlusal reduction with a uniform thickness of the substructure (0.3 mm) and the veneering porcelain (1.5 mm); (2) flat occlusal reduction with different thicknesses of veneering porcelain to produce a uniform substructure; and (3) a flat occlusal reduction with different thicknesses of substructure for a uniform thickness of veneering porcelain. RESULTS: Stress distributions were very similar in the three models. The highest tensile stresses were concentrated immediately below the midline fissure in both the veneering porcelain and the metal alloy substructure. Although models with flat occlusal reduction had lower stress values, this preparation results from a reduction that removes a greater amount of sound tissue, which may increase the probability of dental pulp injury. CONCLUSIONS: Occlusal reduction must be anatomic; however, when a flat occlusal reduction already exists, the substructure must reproduce the correct anatomic form to allow a uniform thickness of the veneering porcelain.
Assuntos
Coroas , Porcelana Dentária/química , Planejamento de Prótese Dentária , Análise de Elementos Finitos , Imageamento Tridimensional/métodos , Ligas Metalo-Cerâmicas/química , Preparo Prostodôntico do Dente/métodos , Silicatos de Alumínio/química , Dente Pré-Molar/anatomia & histologia , Fenômenos Biomecânicos , Ligas de Cromo/química , Facetas Dentárias , Dentina/anatomia & histologia , Humanos , Teste de Materiais , Compostos de Potássio/química , Estresse Mecânico , Propriedades de Superfície , Cimento de Fosfato de Zinco/químicaRESUMO
BACKGROUND: The purpose of this study is to analyze the tension distribution on bone tissue around implants with different angulations (0°, 17°, and 30°) and connections (external hexagon and tapered) through the use of three-dimensional finite element and statistical analyses. METHODS: Twelve different configurations of three-dimensional finite element models, including three inclinations of the implants (0°, 17°, and 30°), two connections (an external hexagon and a tapered), and two load applications (axial and oblique), were simulated. The maximum principal stress values for cortical bone were measured at the mesial, distal, buccal, and lingual regions around the implant for each analyzed situation, totaling 48 groups. Loads of 200 and 100 N were applied at the occlusal surface in the axial and oblique directions, respectively. Maximum principal stress values were measured at the bone crest and statistically analyzed using analysis of variance. Stress patterns in the bone tissue around the implant were analyzed qualitatively. RESULTS: The results demonstrated that under the oblique loading process, the external hexagon connection showed significantly higher stress concentrations in the bone tissue (P <0.05) compared with the tapered connection. Moreover, the buccal and mesial regions of the cortical bone concentrated significantly higher stress (P <0.005) to the external hexagon implant type. Under the oblique loading direction, the increased external hexagon implant angulation induced a significantly higher stress concentration (P = 0.045). CONCLUSIONS: The study results show that: 1) the oblique load was more damaging to bone tissue, mainly when associated with external hexagon implants; and 2) there was a higher stress concentration on the buccal region in comparison to all other regions under oblique load.
Assuntos
Projeto do Implante Dentário-Pivô , Implantação Dentária Endóssea/métodos , Implantes Dentários , Análise de Elementos Finitos , Imageamento Tridimensional/métodos , Silicatos de Alumínio/química , Processo Alveolar/fisiologia , Força de Mordida , Ligas de Cromo/química , Simulação por Computador , Materiais Dentários/química , Porcelana Dentária/química , Módulo de Elasticidade , Humanos , Modelos Biológicos , Distribuição de Poisson , Compostos de Potássio/química , Estresse Mecânico , Titânio/química , Cimento de Fosfato de Zinco/químicaRESUMO
O sistema endocrown está sendo cada vez mais usado para restaurações de dentes posteriores com coroas amplamente destruídas e visa uma máxima preservação de estruturas dentais remanescentes. O tipo de cimentação usado nesses casos é fundamental para o sucesso clínico, já que o cimento é usado para selar a interface dente/restauração unindo-os por algum tipo de interação, seja ela mecânica e/ou química. O objetivo dessa pesquisa foi avaliar qual cimento é mais resistente quando submetidos ao teste de tração. Foram analisados três tipos de cimentos: Fosfato de zinco, ionômero de vidro e resinoso dual. Os testes foram realizados em próteses confeccionadas em resina acrílica e cimentadas em dentes bovinos previamente preparados de forma padronizada. Quando submetidos ao teste de ANOVA, o cimento resinoso dual e o fosfato de zinco apresentaram as maiores médias. Esta proximidade de resultados estimula maiores estudos com a cimentação de Endocrown com cimento convencional
The Endocrown system is being increasingly used for posterior restorations with crowns widely destroyed and aims for maximum preservation of remaining tooth structure. The type of cement used in these cases is crucial for clinical success, since the cement is used to seal the interface tooth/restoration joining them for some kind of interaction, whether mechanical and/or chemical. The purpose of this study was to evaluate which cement is more resistant when submitted to tensile test. Were analyzed three types of cements: zinc phosphate, glass ionomer, and resinous dual. The tests were performed in prostheses made of indirect composite resin and cemented in bovine teeth previously prepared in a standardized manner. When submitted to ANOVA test, the dual resin cement and zinc phosphate presented the highest means. This closeness results encourages further studies with cementation Endocrown with conventional cement
Assuntos
Cimento de Fosfato de Zinco , Cimentos Dentários , Cimentos de Ionômeros de Vidro , Resistência à TraçãoRESUMO
This study evaluated the effect of different ultrasonic vibration protocols on custom cast post-and-cores' retention to the root canal. Post holes were placed in the root canals of human maxillary canines, and post-and-core sets were luted, using zinc phosphate cement. The samples were divided into 5 groups (n = 8). Group 1 (control) received no ultrasonic vibration. For the other samples, the tip of the ultrasonic device was positioned either over the incisal face of the core (Group 2), over the lateral core surfaces and close to the incisal edge (Group 3), over the lateral face of the core but close to the line of cementation (Group 4), or over the lateral face of the core but with the end of the mouth mirror handle positioned on the opposite surface of the core (Group 5). After a tensile test, data were submitted to 2-way ANOVA and Tukey's tests (P < 0.05). The control group showed higher values than all of the groups that were submitted to ultrasonic vibration. Bond strength was similar for Groups 2 and 3. Bond strength was lower in Groups 4 and 5; no statistical difference was observed between these 2 groups. Based on these results, both positioning the tip of the ultrasonic device near the cement line and placing a mouth mirror handle on the opposite surface of the core, are effective ways to reduce the retention of a cast post-and-core within a root canal.
Assuntos
Colagem Dentária , Retenção em Prótese Dentária , Cavidade Pulpar/patologia , Técnica para Retentor Intrarradicular/instrumentação , Cimentação/métodos , Ligas de Cromo/química , Dente Canino/patologia , Análise do Estresse Dentário/instrumentação , Humanos , Umidade , Teste de Materiais , Preparo de Canal Radicular/instrumentação , Preparo de Canal Radicular/métodos , Estresse Mecânico , Propriedades de Superfície , Resistência à Tração , Fatores de Tempo , Ultrassom , Vibração , Cimento de Fosfato de Zinco/químicaRESUMO
STATEMENT OF PROBLEM: Although cement-retained implant prostheses are widely used, the quantification of optimal retention remains controversial, and new dental luting agents should be evaluated. PURPOSE: The purpose of this study was to compare, in vitro, the casting retention on implant abutments after cementation with 3 commercially available luting agents and an experimental luting agent (castor oil polyurethane, COP) with variable weight percentages (wt%) of calcium carbonate (CaCO3). MATERIAL AND METHODS: Seventy-two palladium-silver cast copings were fabricated and divided into 6 groups: Temp Bond interim cement (TB); zinc phosphate cement (ZP); Rely X ARC resin cement (RX); pure COP (COP); COP + 10% wt% CaCO3 filler (COP 10); and COP + 50% wt% CaCO3 filler (COP 50). After cementation, the specimens were stored in distilled water at 37°C for 24 hours and subjected to removal force tests in a universal testing machine (5 kN; 0.5 mm/min). Statistical analyses were performed with the Kruskal-Wallis and Student-Newman-Keuls tests (α=.05). RESULTS: The median values of casting retention (N) were as follows: TB=57.20 ±10.4; ZP=343.56 ±50.3; RX=40.07 ±9.7; COP=258.98 ±41.4; COP 10=466.57 ±79.3; and COP 50=209.63 ±31.4. The Kruskal-Wallis test showed significant differences among the groups (P<.01). TB and RX had the lowest mean retention values; COP, COP 10, and COP 50 were equal to ZP, and COP 10 had the highest retention. CONCLUSIONS: The casting retention on implant-abutments provided by COP was similar to that of copings cemented with zinc phosphate and may be influenced by the addition of calcium carbonate.
Assuntos
Óleo de Rícino/química , Cimentação/métodos , Cimentos Dentários/química , Projeto do Implante Dentário-Pivô , Retenção em Prótese Dentária , Bis-Fenol A-Glicidil Metacrilato/química , Carbonato de Cálcio/química , Coroas , Ligas Dentárias/química , Análise do Estresse Dentário/instrumentação , Eugenol/química , Humanos , Teste de Materiais , Paládio/química , Polietilenoglicóis/química , Ácidos Polimetacrílicos/química , Poliuretanos/química , Cimentos de Resina/química , Resinas Vegetais/química , Prata/química , Estresse Mecânico , Temperatura , Fatores de Tempo , Água/química , Óxido de Zinco/química , Cimento de Fosfato de Zinco/químicaRESUMO
AIM: This study was undertaken to examine the effect of root canal (RT) sealers content and the cleaning procedure of RT walls on bond strength (BS) of a fiber reinforced composite (FRC) post cemented with resin-based or zinc phosphate cement. MATERIALS AND METHODS: Forty bovine roots were divided into 2 groups (n = 20) and obturated with gutta-percha points plus Sealer 26 sealer or gutta-percha points plus N-Rickert sealer. In each group, half (n = 10) of intracanal walls was cleaned with ethanol and the other half with sulfuric ether. In each of these subgroups, half of intracanal posts (n = 5) were cemented with Bistite resin-based cement and half with zinc phosphate cement. Specimens were submitted to pull-out test and tensile force until post dislodgement. The maximum forces required for post removal was expressed in MPa, means were submitted to statistical analysis (Analysis of Variance Test, a = 0.05). RESULTS: Fiber reinforced composite cemented with zinc phosphate were significantly more retentive than those cemented with Bistite (p < 0.05). Regarding the influence of eugenol-based sealer on post retention, there was a statistically significant difference (p < 0.05) only between groups cemented with Bistite, in which canals filled with N-Rickert + gutta-percha showed lower BS than canals filled with Sealer 26 + gutta-percha. CONCLUSION: Despite endodontic cement used, higher pull-out bond strength were obtained when posts were cemented with zinc phosphate. CLINICAL SIGNIFICANCE: The importance of ethanol or sulphuric ether application to properly replace water from intraradicular dentine still requires further investigations, especially to clarify if this technique may reduce the effect of aging and improve the stability of the bond, when used to cement fiber posts into the root canal.
Assuntos
Colagem Dentária , Técnica para Retentor Intrarradicular , Materiais Restauradores do Canal Radicular/química , Preparo de Canal Radicular , Solventes , Animais , Bismuto , Hidróxido de Cálcio , Bovinos , Resinas Compostas , Análise do Estresse Dentário , Etanol , Éteres , Eugenol , Vidro , Solventes/química , Resistência à Tração , Cimento de Fosfato de ZincoRESUMO
The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used.
Assuntos
Animais , Bovinos , Polimento Dentário/instrumentação , Técnica para Retentor Intrarradicular , Cimento de Fosfato de Zinco/química , Intervalos de Confiança , Cimentação/métodos , Instrumentos Odontológicos , Retenção em Prótese Dentária , Polimento Dentário/métodos , Teste de Materiais , Propriedades de Superfície , Resistência à Tração , Fatores de TempoRESUMO
The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukey's test (α = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used.
Assuntos
Polimento Dentário/instrumentação , Técnica para Retentor Intrarradicular , Cimento de Fosfato de Zinco/química , Animais , Bovinos , Cimentação/métodos , Intervalos de Confiança , Instrumentos Odontológicos , Polimento Dentário/métodos , Retenção em Prótese Dentária , Teste de Materiais , Propriedades de Superfície , Resistência à Tração , Fatores de TempoRESUMO
This in vitro study compared different ultrasonic vibration modes for intraradicular cast post removal. The crowns of 24 maxillary canines were removed, the roots were embedded in acrylic resin blocks, and the canals were treated endodontically. The post holes were prepared and root canal impressions were taken with self-cured resin acrylic. After casting, the posts were cemented with zinc phosphate cement. The samples were randomly distributed into 3 groups (n=8): G1: no ultrasonic vibration (control); G2: tip of the ultrasonic device positioned perpendicularly to core surface and close to the incisal edge; and G3: tip of the ultrasonic device positioned perpendicularly to core surface at cervical region, close to the line of cementation. An Enac OE-5 ultrasound unit with an ST-09 tip was used. All samples were submitted to the tensile test using an universal testing machine at a crosshead speed of 1 mm/min. Data were subjected to one-way ANOVA and Tukey's post-hoc tests (α=0.05). Mean values of the load to dislodge the posts (MPa) were: G1 = 4.6 (± 1.4) A; G2 = 2.8 (± 0.9) B, and G3= 0.9 (± 0.3) C. Therefore, the ultrasonic vibration applied with the tip of device close to the core's cervical area showed higher ability to reduce the retention of cast post to root canal.
Assuntos
Descolagem Dentária/instrumentação , Técnica para Retentor Intrarradicular/instrumentação , Ultrassom/instrumentação , Vibração , Cimento de Fosfato de Zinco/química , Análise de Variância , Cimentação , Dente Canino/cirurgia , Análise do Estresse Dentário/métodos , Humanos , Técnicas In Vitro , Tratamento do Canal Radicular/métodosRESUMO
AIMS AND OBJECTIVES: to evaluate the resistance to displacement of metal intraradicular retainers of different lengths by means of the shear test. MATERIAL AND METHODS: Thirty-six maxillary central incisors were cross-sectioned at 16 mm from the root apex, endodontically treated and randomly divided into three groups that were treated as follows: G1 (control) preparation of 2/3 (10.6 mm) of the total root length; G2: preparation of 1/2 (8 mm) of the total root length and G3: preparation of 1/3 (5.3 mm) of the total root length. After canal preparation, a matrix was made of the coronal and radicular portions using Duralay to obtain metal intraradicular retainers. These retainers were cemented with zinc phosphate cement and subjected to the compression shear test in a Universal Test Machine (EMIC DL 2000) at a crosshead speed of 0.5 mm/minute. The results were subjected to statistical analysis by analysis of variance (ANOVA) and Newman- Keuls, which showed statistically significant difference (P < 0.01). RESULTS: The means in Newtons and their respective standard deviations were: G1 = 972.05 (±81.36); G2 = 921.15 (±112.25); G3 = 686.66 (±113.02). CONCLUSION: It could be concluded that metal retainers of 2/3 and 1/2 the length of the root portion showed higher resistance to displacement values when compared with the group that had been prepared for 1/3 of the root length.