Association between the facial type and morphology of the upper central incisor in normal occlusion subjects.

AIM: The purpose of this study was to verify the association between the facial type and the morphology of the upper central incisor, to potentially provide a guide for artificial tooth selection in esthetic and prosthetic rehabilitation. MATERIALS AND METHODS: The sample consisted of 51 lateral teleradiographs (lateral cephalometric radiographs) and cast models of subjects with a naturally optimal occlusion and at least four of the six keys of Andrews, for optimal occlusion. The facial type was defined by two cephalometric measurements (SN.Gn and SN.GoGn) and classified into dolichofacial, meso- facial and brachyfacial after digitizing the radiographs. The incisor morphology was classified into quadrangular, oval and triangular after 3D digitizing the models and evaluation of the images by 12 dentists. The evaluation between the examiners was performed by Kappa test. In order to test the differences between the variables, it was used a chi-square test (5%). RESULTS: No significant difference (p < 0.05) was found between the studied variables. CONCLUSION: Facial type was not associated with the morphology of the upper central incisor, considering the methodology and population included in the present study. CLINICAL SIGNIFICANCE: Using the facial type as a way to select the morphology of the upper central incisor proved to be inadequate in this study.

Effect of cement shade and light-curing unit on bond strength of a ceramic cemented to dentin.

PURPOSE: To evaluate the effect of cement shade, light-curing unit, and water storage on tensile bond strength (σ) of a feldspathic ceramic resin bonded to dentin. MATERIALS AND METHODS: The dentin surface of 40 molars was exposed and etched with 37% phosphoric acid, then an adhesive system was applied. Forty blocks of feldspathic ceramic (Vita VM7) were produced. The ceramic surface was etched with 10% hydrofluoric acid for 60 s, followed by the application of a silane agent and a dual-curing resin cement (Variolink II). Ceramic blocks were cemented to the treated dentin using either A3 or transparent (Tr) shade cement that was activated using either halogen or LED light for 40 s. All blocks were stored in 37°C distilled water for 24 h before cutting to obtain non-trimmed bar-shaped specimens (adhesive area = 1 mm2 ± 0.1) for the microtensile bond strength test. The specimens were randomly grouped according to the storage time: no storage or stored for 150 days in 37°C distilled water. Eight experimental groups were obtained (n = 30). The specimens were submitted to the tensile bond strength test using a universal testing machine at a crosshead speed of 1 mm/min. The data were statistically analyzed using ANOVA and Tukey's posthoc tests (a = 0.05). RESULTS: The mean bond strength values were significantly lower for the corresponding water stored groups, except for the specimens using A3 resin cement activated by halogen light. There was no significance difference in mean bond strength values among all groups after water storage. CONCLUSION: Water storage had a detrimental effect under most experimental conditions. For both cement shades investigated (Tr and A3) under the same storage condition, the light-curing units (QTH and LED) did not affect the mean microtensile bond strengths of resin-cemented ceramic to dentin.

Effect of carbon and glass fiber posts on the flexural strength and modulus of elasticity of a composite resin.

The aim of this study was to evaluate the effect of prefabricated fiber posts on the flexural strength and modulus of elasticity of a composite resin. Thirty bar-shaped specimens measuring 25 x 2.0 x 2.0 mm were made, containing posts that were 1.3 mm in diameter and 20 mm long. Each group contained 10 specimens: Group 1, resin without post; Group 2, resin with carbon fiber post; Group 3, resin with glass fiber post. The samples were immersed in water at 37 degrees C until the three-point loading test was performed at a speed of 1.0 mm/minute. The results were statistically analyzed by ANOVA and Tukey's test (P = 0.05). Both fiber posts were similar in strength and both were stronger than the control. Group 3 obtained a higher mean modulus of elasticity than Groups 1 and 2, which were similar. The results of this study demonstrated that the presence of a fiber post significantly raised flexural strength values and the glass fiber post significantly increased the modulus of elasticity of the evaluated composite resin.

Evaluación de la Resistencia de Unión de Brackets Ortodónticos Fijados a Cerámica de Disilicato de Litio / Evaluation of Union Resistance of Orthodontic Bracelets Fixed to Lithium Dissylate Ceramic

RESUMEN: El objetivo de este trabajo consistió en evaluar la resistencia al cizallamiento de brackets ortodónticos cementados a una cerámica odontológica a base de disilicato de litio. Fueron confeccionadas 80 muestras rectangulares de cerámica vítrea a base de disilicato de litio. Las muestras fueron divididas inicialmente en 4 grupos de 20 discos según el tratamiento de superficie: ácido fosfórico 37 % por 30 segundos (HP); ácido hidrofluorhidro 10 % por 60 segundos (HF); óxido de aluminio durante 4 segundos (SB); y aspersión con punta diamantada durante 10 segundos (DW). Cada grupo fue dividido en dos subgrupos para la cementación de brackets Edgwise: metálico y cerámico. Los dos nuevos grupos fueron subdivididos en termociclados o no termociclados. Las muestras termocicladas pasaron por 500 ciclos con variaciones de temperatura entre 5 °C a 55 °C. Los valores numéricos obtenidos en la prueba de cizallamiento se sometieron al análisis estadístico descriptivo (media y desviación estándar), habiéndose realizado la prueba de normalidad Shapiro-Wilk y las pruebas no paramétricas de Kruskal-Wallis y Mann-Whitney. Se verificó que no hubo diferencia estadísticamente significativa en relación al tipo de tratamiento de superficie y la realización o no de termociclado, observándose diferencia estadísticamente significativa sólo en el tipo de bracket, siendo la resistencia de unión en el bracket metálico mayor que en el de cerámica. Así, el tipo de tratamiento de superficie y el envejecimiento por termociclaje no fueron decisivos en la resistencia de unión de brackets ortodónticos a la cerámica de disilicato de litio.

ABSTRACT: To evaluate the shear strength of cemented orthodontic brackets to a dental ceramic based on lithium disilicate. Rectangular samples 80 based glassceramic lithium disilicate were prepared. The samples were initially divided into 4 groups of 20 discs according to surface treatment: 37 % phosphoric acid for 30 seconds (HP); 10 % hydrofluoric acid for 60 seconds (HF); blasting with aluminum oxide for 4 seconds (SB); and diamond-tipped for 10 seconds (DW). Each group was divided into two subgroups for the Edgwise bracket cementation: metallic and ceramic. The two new groups were subdivided into thermocyclers or nonthermocyclics. The thermocycled samples passed 500 cycles with temperature variations between 5 ° C to 55 ° C. The numerical values obtained in the shear test were submitted to descriptive statistical analysis (mean and standard deviation), and the Shapiro-Wilk normality test and nonparametric Kruskal-Wallis and Mann-Whitney tests were performed. It was found that there was no statistically significant difference in the type of surface treatment and conducting or not thermocycling, observing statistically significant difference only on the bracket type, and the bond strength at higher metal bracket than in ceramics. Thus, the type of surface treatment and thermocycling aging were not decisive in the bond strength of orthodontic brackets to the lithium disilicate ceramic.

Evaluation of the Accuracy of Conventional and Digital Methods of Obtaining Dental Impressions / Evaluación de la Exactitud de los Métodos Convencionales y Digitales de la Obtención de Impresiones Dentales

ABSTRACT: The aim of this study was to carry out a literature review on the accuracy of conventional and digital dental impression methods, as well as present the various three-dimensional intraoral scanning systems. A bibliographic search was carried out in PUBMED's main health database, in which works published between 2008 and 2018 were collected. Laboratory studies, case reports and systematic reviews were included, addressing topics that deal with conventional digital materials, impression and precision. Articles that did not evaluate impression materials, their behavior and techniques to obtain a good impression of oral structures were excluded. Through a review in the literature, obtained the following findings: the most critical stage in macking a dental prothesis is to take the dental impression. The conventional technique of impression consists of obtaining a negative copy of the intra-oral situation that will be poured into gypsum, obtaining a positive copy, on which the work will be carried out. Digital scanning systems were not superior to conventional moldings when comparing fidelity, accuracy and detail reproduction; in contrast, they were superior to conventional impression when considering clinical chair time, patient and operator preference, and patient comfort.

RESUMEN: El objetivo de este estudio consistió en realizar una revisión bibliográfica sobre la precisión de los métodos de moldeo dental convencionales y digitales, así como presentar los diversos sistemas de escaneo intraoral tridimensionales. Se realizó una búsqueda bibliográfica en la base de datos de salud principal de PUBMED en la cual se recopilaron trabajos publicados entre 2008 y 2018. Se incluyeron estudios de laboratorio, informes de casos y revisiones sistemáticas, abordando temas que tratan con materiales digitales convencionales, moldeo y precisión. Se excluyeron los artículos que no evaluaron los materiales de moldeo, su comportamiento y técnicas para obtener una buena impresión de las estructuras orales. A través de una revisión exhaustiva en la literatura, obtuvimos los siguientes hallazgos: el paso más crítico en la preparación de una pieza protésica es la impresión de la preparación. La técnica convencional de moldeo consiste en obtener una copia negativa de la situación intraoral que se verterá en el yeso, obteniendo una copia positiva, sobre la cual se realizará el trabajo. Resulta que los sistemas de escaneo digital no fueron superiores a las molduras convencionales al comparar la fidelidad, precisión y reproducción de detalles; en cambio, fueron superiores a las molduras convencionales al considerar el tiempo de trabajo clínico, la preferencia del paciente y del operador y la comodidad del paciente.

Fracture resistance of bovine incisors restored with different glass fiber posts: effect of the diameter of fiber post.

AIM: Compare the effect of three post designs on the fracture resistance and failure modes of composite core - fiber post - crownless tooth sets. MATERIALS AND METHODS: Ninety bovine incisors were selected and divided into nine groups of 10 specimens. The teeth were assigned to three groups based on the post design: Cylindrical, tapered, and double-tapered. Each group was subdivided into three subgroups in accordance with the diameter of the post: Small (No.1), medium (No.2), and large (No.3). The Panavia F system was used for post cementation. The specimens were mounted in acrylic resin blocks with a layer of silicone rubber covering the roots. A universal testing machine compressively loaded the specimens from the palatal side at a crosshead speed of 1 mm/min and at an angle of 135Ί to the long axis of the teeth, until failure occurred. The failure mode was determined by a stereomicroscope inspection of all the specimens. Data were analyzed by one-way ANOVA and the Tukey test (P < 0.05). RESULTS: The fracture resistance was affected by the type of post (P < 0.0001). A narrower diameter for all of the post systems allowed for higher resistance. The main failure mode in the large cylindrical group was catastrophic fractures, while the main failures in the other eight groups were favorable. CONCLUSION: Narrower diameter posts showed higher fracture resistance. The dominant failure pattern was repairable fracture, except for those with large cylindrical groups.

Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic.

The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

Resistance to compression of weakened roots subjected to different root reconstruction protocols.

OBJECTIVE: This study evaluated, in vitro, the fracture resistance of human non-vital teeth restored with different reconstruction protocols. MATERIAL AND METHODS: Forty human anterior roots of similar shape and dimensions were assigned to four groups (n=10), according to the root reconstruction protocol: Group I (control): non-weakened roots with glass fiber post; Group II: roots with composite resin by incremental technique and glass fiber post; Group III: roots with accessory glass fiber posts and glass fiber post; and Group IV: roots with anatomic glass fiber post technique. Following post cementation and core reconstruction, the roots were embedded in chemically activated acrylic resin and submitted to fracture resistance testing, with a compressive load at an angle of 45º in relation to the long axis of the root at a speed of 0.5 mm/min until fracture. All data were statistically analyzed with bilateral Dunnett's test (α=0.05). RESULTS: Group I presented higher mean values of fracture resistance when compared with the three experimental groups, which, in turn, presented similar resistance to fracture among each other. None of the techniques of root reconstruction with intraradicular posts improved root strength, and the incremental technique was suggested as being the most recommendable, since the type of fracture that occurred allowed the remaining dental structure to be repaired. CONCLUSION: The results of this in vitro study suggest that the healthy remaining radicular dentin is more important to increase fracture resistance than the root reconstruction protocol.

Fracture resistance of endodontically treated teeth with different heights of crown ferrule restored with prefabricated carbon fiber post and composite resin core by intermittent loading.

This study evaluated the fracture resistance of endodontically treated teeth restored with prefabricated carbon fiber posts and varying quantities of coronal dentin. Sixty freshly extracted upper canines were randomly divided into groups of 10 teeth each. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis. Data were analyzed by 1-way analysis of variance and Tukey test (alpha = .05). Significant differences (P < .001) were found among the mean fracture forces of the test groups (positive control, 0 mm,1 mm, 2 mm, 3 mm, and negative control groups: 1022.82 N, 1008.22 N, 1292.52 N, 1289.19 N, 1255.38 N, and 1582.11, respectively). These results suggested that the amount of coronal dentin did not significantly increase the fracture resistance of endodontically treated teeth restored with prefabricated carbon fiber post and composite resin core.

Fracture resistance of weakened roots restored with composite resin and glass fiber post.

This study evaluated the fracture resistance of weakened roots restored with glass fiber posts, composite resin cores and complete metal crowns. Thirty maxillary canines were randomly divided into 3 groups of 10 teeth each: teeth without weakened roots (control); teeth with partially weakened roots (PWR) and teeth with and largely weakened roots (LWR). The control group was restored with glass fiber posts and a composite resin core. Teeth in the PWR and LWR groups were flared internally to standardized dimensions in order to simulate root weakness. Thereafter, the roots were partially filled with composite resin and restored in the same way as in the control group. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis of the tooth until failure. Data were analyzed by one-way ANOVA and Dunnett's test for multiple comparisons (p=0.05). There were statistically significant difference differences (p<0.01) among the groups (control group = 566.73 N; PWR = 409.64 N; and LWR = 410.91 N), with significantly higher fracture strength for the control group. There was no statistically significant difference (p>0.05) between the weakened groups. The results of this study showed that thicker root dentin walls significantly increase the fracture resistance of endodontically treated teeth.

Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic

The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9 percent hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

O objetivo deste estudo foi avaliar o efeito de diferentes tempos de condicionamento ácido na rugosidade de superfície e resistência flexural de uma cerâmica à base de disilicato de lítio. Espécimes cerâmicos em forma de barra (16 mm x 2 mm x 2 mm) foram produzidos a partir de blocos cerâmicos. Todos os espécimes foram polidos e limpos em banho de ultrasom em água destilada. Os espécimes foram aleatoriamente divididos em 5 grupos (n=15). Grupo A (controle) sem tratamento. Grupos B-E condicionamento com ácido fluorídrico 4,9 por cento (HF) por 4 diferentes períodos de condicionamento: 20 s, 60 s, 90 s e 180 s, respectivamente. As superfícies condicionadas foram observadas sob microscopia eletrônica de varredura. Perfilometria de superfície foi utilizada para examinar a rugosidade das superfícies condicionadas, e os espécimes foram carregados até a falha pelo teste de flexão três pontos. Os valores foram analisados usando ANOVA um fator e teste de Tukey (?=0,05). Todos os períodos de condicionamento produziram superfícies significantemente mais rugosas do que o grupo controle (p<0,05). Os valores de rugosidade aumentaram com o tempo de condicionamento. Os valores médios de resistência à flexão foram (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; e E=314 ± 62. O condicionamento com HF reduziu significativamente os valores médios de resistência à flexão conforme o tempo de condicionamento aumentou (p=0,003). Os achados deste estudo mostraram que o aumento do tempo de condicionamento ácido influenciou a rugosidade de superfície e resistência flexural de uma cerâmica à base de disilicato de lítio confirmando a hipótese do mesmo.

Resistance to compression of weakened roots subjected to different root reconstruction protocols

OBJECTIVE: This study evaluated, in vitro, the fracture resistance of human non-vital teeth restored with different reconstruction protocols. MATERIAL AND METHODS: Forty human anterior roots of similar shape and dimensions were assigned to four groups (n=10), according to the root reconstruction protocol: Group I (control): non-weakened roots with glass fiber post; Group II: roots with composite resin by incremental technique and glass fiber post; Group III: roots with accessory glass fiber posts and glass fiber post; and Group IV: roots with anatomic glass fiber post technique. Following post cementation and core reconstruction, the roots were embedded in chemically activated acrylic resin and submitted to fracture resistance testing, with a compressive load at an angle of 45º in relation to the long axis of the root at a speed of 0.5 mm/min until fracture. All data were statistically analyzed with bilateral Dunnett's test (α=0.05). RESULTS: Group I presented higher mean values of fracture resistance when compared with the three experimental groups, which, in turn, presented similar resistance to fracture among each other. None of the techniques of root reconstruction with intraradicular posts improved root strength, and the incremental technique was suggested as being the most recommendable, since the type of fracture that occurred allowed the remaining dental structure to be repaired. CONCLUSION: The results of this in vitro study suggest that the healthy remaining radicular dentin is more important to increase fracture resistance than the root reconstruction protocol.

Influência de diferentes dispositivos de ensaio utilizados no teste de resistência de união ao cisalhamento do titânio (TICP) a uma resina indireta / Influence of different test devices used on the shear bond strength test of titanium to indirect composite

Avaliar a influência de diferentes dispositivos decarregamento na resistência de união ao cisalhamento entreo titânio comercialmente puro (Ticp) e uma resina indireta.Materiais e Método: Foram confeccionados trinta cilindrosmetálicos (CM) em Ticp (altura: 5 mm; diâmetro: 4 mm). OsCM tiveram sua superfície adesiva jateada com Al2O3 110 μm.Todos os cilindros foram imersos em álcool isopropílico 10% elimpos em banho ultra-sônico (10 min). Duas camadas(espessura: 0,2 mm) de Sinfony Opaco foram aplicadas sobrea superfície jateada dos CM e submetidas à polimerização nasunidades Visio Alfa e Visio Beta. Com auxílio de um dispositivode teflon, a resina de recobrimento estético Sinfony foi aplicada(altura: 5 mm; diâmetro: 4 mm) sobre a camada de opaco epolimerizada de acordo com as recomendações do fabricante.As amostras foram divididas em três grupos, de acordo com otipo de dispositivo para carregamento utilizado para o ensaiode cisalhamento (n=10): Gr1- pistão, Gr2- cinzel reto e Gr3-cinzel reto com entalhe. As amostras foram submetidas aoensaio de cisalhamento na máquina de ensaio universal. Osdados (MPa) foram submetidos à análise de variância (ANOVA).Resultados: As médias e desvios-padrões obtidos foram: Gr1-5,49±1,41 MPa; Gr2- 5,37±0,8 MPa e Gr3- 5,56±1,92 MPa.Conclusão: Todos os dispositivos testados apresentaramdesempenho semelhante na análise da união metal/resina(p=0,9550>0,05)...

The aim of this study was to evaluate the influenceof the different devices on the shear bond strength betweenthe titanium (Ticp) and an indirect resin. Material and Method:Thirty metallic cylinders of Ticp (height: 5 mm; diameter: 4mm) obtained by machining of pure commercially titaniumbar (Ticp). The metallic cylinders had their adhesive surfacesandblasted (Al2O3; 110μm). All cylinders were immerged inisopropyl alcohol 10% and were cleaned ultrasonically (10min). Two layers of the resin Opaque Sinfony were applied onthe metallic cylinders and cured in the Visio Alfa and VisioBeta units, according to the manufacturer’s recommendation.The esthetic resin Sinfony was applied (height: 5 mm; diameter:4 mm) on the opaque layer using a teflon device, according tothe manufacturer’s instructions. The specimens were dividedinto three groups, according to the shear device used (n=10):Gr1: piston, Gr2: knife without a groove; Gr3: knife with a groove.The shear test was performed in a universal testing machine.Bond strength results were analyzed using one-way ANOVA.Results: The means and standard deviations obtained were:Gr1- 5.49 ± 1.41 MPa, Gr2- 5.37 ± 0.8 MPa and Gr3- 5.56 ±1.92 MPa. Conclusion: All devices used showed similarperformance on the bond strength between metal/resin(p=0.9550>0.05)...

Efeito do tratamento de superfície do titânio comercialmente puro na resistência de união ao cisalhamento / Effect of the surface treatment of commercially pure titanium on the shear bond strength

Objetivo: Avaliar a resistência de união ao cisalhamento entre um material de revestimento estético e um metal submetido a três tratamentos de superfície. Método: Foram confeccionados trinta cilindros metálicos, com 5 mm de comprimento e 4mm de diâmetro cada, obtidos por meio de usinagem de barras de titânio comercialmente puro (Ticp). Os cilindros foram divididos em três grupos conforme o tratamento superficial (n=10): Grupo 1 - jateamento com óxido de alumínio (150 micrometros); Grupo 2 - Sistema Rocatec (3M/ESPE): jateamento com óxido de alumínio (Al2O3) 110 micrometros (Rocatec-pre powder) e com sílica (Rocatec-plus powder) + silano (Rocatec-Sil) e Grupo 3 - Sistema CoJet (3M/ESPE): jateamento com partículas de sílica 30 micrometros + Silano (ESPE Sil). Para confecção dos espécimes, foi aplicado sobre cada base metálica o sistema opaco (Sinfony Opaco, 3M ESPE/EUA) e posteriormente a resina composta para restauração indireta (Sinfony, 3M ESPE/EUA). Os espécimes foram armazenados em água destilada (37 graus Celsius / 24 horas) e submetidos ao ensaio de cisalhamento em máquina de ensaio universal (EMIC, modelo DL- 1000), com célula de carga de 500 Kgf, a uma velocidade constante de 0,5mm/min. Os dados obtidos (MPa) foram submetidos ao teste ANOVA (1 fator) e teste de Tukey (5%). Resultados: Observou-se que o grupo 1 (20,01 - 3,12) diferiu estatisticamente do grupo 2 (27,83 - 3,02) e do grupo 3 (26,91 - 3,65) que, entre si, não diferiram estatisticamente. Conclusão: O tratamento da superfície do Ticp com Rocatec ou CoJet gera maior resistência de união entre o Ticp e a resina Sinfony.

Objective: To assess the shear bond strength of an esthetic coatingmaterial and a metal subjected to three surface treatments. Methods: Thirty metallic cylinders (5 mm high x 4 mm diameter) were fabricated from machining of commercially pure titanium (CPTi) bars. The cylinders were assigned to three groups (n=10), according to the surface treatment: Group 1: 150- micrometrics aluminum oxide particle air abrasion; Group 2 - Rocatec system (3M/ESPE):110- micrometrics aluminum oxide particle air abrasion (Rocatec-pre powder) and silica air abrasion (Rocatec-plus powder) + silane (Rocatec- Sil); and Group 3 - CoJet system (3M/ESPE): 30- micrometrics silica particle air abrasion + silane (ESPE Sil). The specimens were fabricated by applying the opaque system (Sinfony Opaco, 3M/ESPE) followed by indirect composite resin (Sinfony, 3M ESPE/USA). After storage in distilled water at 37 degrees celsius for 24 hours, the specimens were tested in shear strength in a universal testing machine (EMIC, model DL- 1000) with a 500 kgf charge cell at 0.5 mm/min crosshead speed. The obtained data (MPa) were subjected to one-way ANOVA and Tukey's test at 5% significance level. Results: Group 1 (20.01 - 3.12) was statistically different from Group 2 (27.83 -3.02) and Group 3 (26.91 - 3.65). Groups 2 and 3 did not differ significantly from each other. Conclusion: The surface treatment of CPTi with Rocatec or CoJet produced greater bond strength between CPTi and Sinfony composite resin.

O efeito da temperatura de queima da camada de opaco na resistência flexural de uma cerâmica vítrea submetida à cocção sobre uma liga decobalto-cromo / Opaque layer firing temperature effect on the flexural strength of glass ceramic fused to cobalt-chromium alloy

Este estudo avaliou a influência da temperatura de queima da camada de opaco na resistência de união entre uma liga de cobalto-cromo e uma cerâmica, após serem submetidos ao ensaio de flexão de três pontos. Considera-se a hipótese: o aumento da temperatura de queima do opaco melhora a resistência flexural da cerâmica aplicada sobre o metal. Barras metálicas (25x3x0,5mm) (n=30) foram fundidas em Co-Cr e as áreas centrais das barras (8x3mm) foram jateadas com partículas de óxido de alumínio de 150μm e divididas em 3 grupos de acordo com a temperatura de queima da camada de opaco (n=10): G1 (grupo controle) – 900°C; G2 – 950°C e G3 – 1000°C. As cerâmicas opaca e de corpo (Vita Omega 900) foram queimadas sobre a área central. Os espécimes foram mantidos em água destilada à 37° C durante 24 horas e a seguir foram submetidos ao teste de flexão de três pontos. Após o teste, os tipos de falhas foram classificados. Os dados obtidos foram analisados estatisticamente (Kruskal-Wallis 1 e teste de Dunn , μ=0,05). A diferença dos valores médios de resistência flexural foi estatisticamente significante (p=0,004), sendo que os grupos G2- 19,84±4,24N e G3- 22,43±5,94N exibiram valores de resistência flexural maiores que o grupo G1-12,525±1,08N. Concluiu-se que o aumento da temperatura de queima da camada de opaco melhorou significantemente os valores de resistência flexural. O modo de falha predominante foi adesiva na interface metal/cerâmica para o grupo G1 e exclusivamente coesiva na zona interfacial camada de opaco/Co-Cr com presença de cerâmica na superfície dos grupos G2 e G3.

This study evaluated the opaque layer firing temperature on the flexural strength of a ceramic fused to commercial cobaltchromiumalloy (Co-Cr). The hypotheses were that opaque layer temperature increasing get higher the metal/ceramicbond strength. Metallic frameworks (25x3x0.5 mm) (n=30) were cast in Co-Cr and airborne particle abraded with 150μm aluminum oxide at the central area of the frameworks (8x3 mm) and after divided into three groups, according toopaque layer firing temperature (n=10): G1 (control) – 900°C; G2- 950°C and G3- 1000°C. Opaque ceramic were appliedand the glass ceramic (Vita Omega 900, Vita Zahnfabrick, Bad Sãckingen, Germany) was fired onto them (thickness:1 mm). The specimens were kept in distilled water at 37ºC for 24 hours, after that it were submitted to three pointsflexural strenght test. After the test, failure types were noted. The data were analyzed using 1 way Kruskal-Wallis andDunn test (5%). The difference in mean flexure strength values were statistically significant (p=0,004). The groups G2-19,84±4,24N and G3- 22,43±5,94N presented higher flexure strength values than G1- 12,525±1,08N. It was concludedthat the opaque layer temperature increasing improved the flexure bond strength values significantly. The failure typepredominant was adhesive at metal/ceramic interface for group G1 sample and exclusively cohesive at the opaqueceramic/Co-Cr interfacial zone with presence of ceramic on the metal surface for groups G2 and G3.

Avaliação da dureza Vickers de resinas compostas de uso direto e indireto / Evaluation of Vickers hardness of direct and indirect composite resins

Objetivo: Este estudo propôs avaliar a microdureza de diferentes resinas compostas de uso direto (rcd) e indireto (rci). Materiais e Métodos: Com o auxílio de uma matriz metálica (diâmetro: 5,0mm; espessura: 2,0mm) foram confeccionadas 70 amostras, sendo (n=10) três resinas de uso direto: Gr1- Z250(3M ESPE/EUA), Gr2- W3D(Wilcos/Brasil) e Gr3- Esthetic X(Dentisply/EUA); e quatro de uso indireto: Gr4- Resilab Master (Wilcos/Brasil), Gr5- Vita VM LC (Vita Zahnfabrik/Alemanha), Gr6- Vita Zeta (Vita Zahnfabrik/Alemanha) e Gr7- Sinfony (3M ESPE/EUA). As amostras das rcd foram confeccionadas utilizando a técnica incremental, onde cada incremento de resina foi fotopolimerizado durante 40 segundos. Já as amostras da rci foram polimerizadas segundo recomendações dos fabricantes. Todos os espécimes foram armazenados em água destilada a 37ºC durante 24 horas. O teste de microdureza foi realizado em microdurômetro digital (Future-Tech,Modelo FM 700), com carga de 50 kgf por 15 segundos. Os dados obtidos (Kgf/mm2) foram analisados utilizando o teste não paramétrico de Kruskal-Wallis e o de comparação múltipla de Dunn (p<0.05). Resultados: As medidas resumo-numéricas de microdureza obtidas foram (mediana; média ± desvio padrão): Gr1 (100,12; 101,07± 5,99 Kgf/mm2), Gr2 (83,55; 84,20± 5,07 Kgf/mm2), Gr3 (73,98; 73,95± 6,55 Kgf/mm2), Gr4 (52,50; 52,54± 5,9 Kgf/mm2), Gr5 (33,25; 34,36± 2,29 Kgf/mm2), Gr6 (29,60; 29.68± 1.52 Kgf/mm2), Gr7 (25,39; 25.13± 2.08 Kgf/mm2). Verificou-se que os valores de microdureza das rcd analisadas não diferiram estatisticamente entre si (p<0,05). O mesmo não se pode estabelecer para as resinas indiretas, pois a Sinfony diferiu da Resilab (p<0,05). Conclusão: Baseado nos resultados pôde-se concluir que apenas a resina composta direta Z250 apresentou valores de microdureza Vickers superior às demais resinas indiretas.

Fracture resistance of weakened roots restored with composite resin and glass fiber post

This study evaluated the fracture resistance of weakened roots restored with glass fiber posts, composite resin cores and complete metal crowns. Thirty maxillary canines were randomly divided into 3 groups of 10 teeth each: teeth without weakened roots (control); teeth with partially weakened roots (PWR) and teeth with and largely weakened roots (LWR). The control group was restored with glass fiber posts and a composite resin core. Teeth in the PWR and LWR groups were flared internally to standardized dimensions in order to simulate root weakness. Thereafter, the roots were partially filled with composite resin and restored in the same way as in the control group. The specimens were exposed to 250,000 cycles in a controlled chewing simulator. All intact specimens were subjected to a static load (N) in a universal testing machine at 45 degrees to the long axis of the tooth until failure. Data were analyzed by one-way ANOVA and Dunnett's test for multiple comparisons (p=0.05). There were statistically significant difference differences (p<0.01) among the groups (control group = 566.73 N; PWR = 409.64 N; and LWR = 410.91 N), with significantly higher fracture strength for the control group. There was no statistically significant difference (p>0.05) between the weakened groups. The results of this study showed that thicker root dentin walls significantly increase the fracture resistance of endodontically treated teeth.

Este estudo avaliou a resistência à fratura de raízes fragilizadas restauradas com pinos de fibra de vidro, núcleos de resina composta e coroas totais metálicas. Trinta caninos superiores foram aleatoriamente divididos em 3 grupos. Dentes sem enfraquecimento (grupo controle); grupo de raízes parcialmente enfraquecidas e amplamente enfraquecidas. O grupo controle foi restaurado com pinos de fibra de vidro e núcleo em resina composta. Os dentes dos grupos de raízes parcialmente e amplamente enfraquecidas foram internamente preparadas de maneira padronizada simulando enfraquecimento. Após isto, as raízes foram parcialmente preenchidas com resina composta e restauradas como no grupo controle. Os espécimes foram expostos a 250.000 ciclos em uma máquina de ciclagem mecânica. Todos os dentes intactos foram submetidos à carga estática (N) em uma máquina de ensaio universal a 45 graus ao longo eixo do dente até a sua falha. Os resultados foram analisados através do teste ANOVA a 1 critério e teste de Dunnett para comparações múltiplas (p=0,05). A análise estatística revelou diferenças significantes (p<0,01) entre os três grupos (grupo controle = 566,73 N; RPE = 409,64 N; e ERA = 410,91 N). Quando as três médias de resistência a fratura são ranqueadas as duas menores não se diferem. Os resultados deste estudo mostraram que uma maior espessura de paredes dentinárias aumenta significantemente a resistência à fratura de dentes tratados endodonticamente.

Conceitos atuais do sistema de encaixe overdenture sobreimplante / An update on attachments for implant-supported overdentures

Diversos sistemas de encaixe utilizados em sobredentaduras nos implantes têm sido desenvolvidos no mercado odontológico. Diante de variada possibilidade, muitas vezes o profissional tem dificuldade de estabelecer critérios seguros na seleção do sistema de encaixe mais adequado a cada caso específico. Desta forma, visando facilitar a escolha profissional, este estudo revisou a literatura nos seus seguintes aspectos: principais sistemas de encaixes (barra, bola, magnetos)/grau de retenção, satisfação do paciente e distribuição de tensões.

Efeito da neutralização e remoção sônica do precipitado do ácido fluorídrico na resistência à fratura de coroas cerâmicas / Effect of neutralization and sonic remotion of the hydrofluoric acid precipitate on the fracture strength of ceramic crowns

Testou-se o efeito de diferentes formas de tratamento da superfície cerâmica após condicionamento com ácido hidrofluorídrico (HF) na resistência à fratura de coroas cerâmicas à base de dissilicato de lítio. Quarenta terceiros molares humanos receberam um preparo convencional para coroa total. Após escaneamento digital dos preparos, blocos cerâmicos foram usinados pelo sistema CAD/CAM para obtenção das coroas. A espessura da película de cimento das coroas ao preparo foi verificada com silicone de adição. As coroas foram distribuídas nos 4 grupos conforme o tratamento da superfície cerâmica (n=10): (HF)- HF à 4.9% por 20s + spray ar-água por 30s; (HFN)– HF + agente neutralizador por 5 min (N); (HFU) – HF + banho sônico por 5 min (U); e (HFNU)– HF +N + U. Após aplicação de uma camada de silano (60s), as coroas foram cimentadas com cimento resinoso dual. Uma carga compressiva de 1000 Kg foi aplicada no centro da face oclusal da coroa com velocidade de 1 mm/min até a fratura. Os dados foram analisados por ANOVA e Tukey (α=0,05). A carga média de fratura (Kgf) foi: HF = 169,92 ± 21,37; HFN =187,34 ± 34,79; HFU = 166,63 ± 40,22 e HFNU = 175,26 ± 40,22. O tratamento da superfície cerâmica após condicionamento ácido não influenciou significativamente (p>0.05) na resistência à fratura das coroas cerâmicas testadas, sugerindo que é desnecessário qualquer tratamento adicional para remoção de resíduos após o uso de HF e lavagem com jato de água-ar.

The effect of different ceramic surface post hydrofluoric acid (HF) etching cleaning protocols in the fracture strength of lithium dissilicate glass ceramic crowns were evaluated. Forty maxillary third human molars received aconventional full preparation. Crowns were obtained from the digital scanning ofthe preparations and CAD/CAM blocks machining. Crown cement film thickness was evaluated with vinyl polysiloxane. The crowns were allocated in 4 groups according to the ceramic surface treatment (n=10): (HF)- 4.9% HF for 20s +water spray for 30s; (HFN)- HF + neutralizing agent for 5 min (N); (HFU) -: HF+sonic bath for 5 min (U) and (HFNU): HF + N + U. After a silane coat (60s), crowns were cemented with dual cure cement. A compressive load of 1000 Kg was applied in the occlusal surface center at crosshead speed of 1mm/min untilthe fracture. Data were analyzed by one-way ANOVA and Tukey tests (α = 0.05). Fracture strength mean for each group was (Kgf): HF = 169.92 ± 21.37; HFN =187.34 ± 34.79; HFU = 166.63 ± 40.22 e HFNU = 175.26 ± 40.22. There was no statistical difference as the surface treatment (p>0.05) suggesting that it is not necessary any additional ceramic surface treatment in order to remove debris after using of HF and air-water spray rinsing.