Caracterização in vitro de um novo sistema de resina composta de laboratório

Aim: this study aimed to determine some of the properties of a laboratory composite indicated for metallic and non-metallic crowns, anterior and posterior bridges, inlays, onlays and laminate veneers. Methology: the properties evaluated were surface roughness, flexural strength, shear bond strength to three metal alloys and the microleakage at the composite/metal interface. All specimens were subjected to cycles of polymerization, according the manufacturer instructions. Ten round specimens (4x3 mm) were prepared for hardness (VHN) and surface roughness tests (Ra). The three-point flexural strength was measured on rectangular shaped specimens (10x5x2 mm), at 1 mm/min speed. The experiments involving dental alloys (bond strength and microleakage) were submitted to statistical analysis (pObjetivo: este estudo caracterizou algumas propriedades de uma resina composta de processamento laboratorial (Resilab, Wilcos do Brasil), indicada para confecção de coroas com e sem metal, pontes anteriores e posteriores, inlays, onlays e facetas laminadas. Metodologia: as propriedades avaliadas foram rugosidade superficial, dureza, resistência à flexão, resistência adesiva a três ligas metálicas (Au, NiCr e CoCr) e microinfiltração da interface resina/metal. Todos os espécimes foram submetidos a dois ciclos de polimerização, conforme instruções do fabricante. Dez espécimes circulares (4x3 mm) foram preparados para os testes de dureza (VHN) e rugosidade superficial (Ra). A resistência flexural em três pontos (MPa) foi medida a partir de espécimes retangulares (10x5x2 mm), sob velocidade de 1 mm/min. Os ensaios que envolveram ligas metálicas (resistência adesiva e microinfiltração) foram submetidos à análise estatística (pResultados: não houve diferenças entre as médias de resistência de união. Quanto à infiltração marginal, o grupo CoCr diferiu dos grupos Au e NiCr em espécimes sem retenção mecânica e submetidos a ciclagem térmica. Conclusão: considerando os resultados deste estudo in vitro e a literatura pesquisada, o sistema Resilab mostrou comportamento satisfatório quanto às propriedades estudadas. A resistência de união não dependeu da liga metálica utilizada

Profundidade de polimerização de cimentos resinosos utilizados na cimentação de pinos translúcidos e sua influência sobre a resistência adesiva antes e após ciclagem mecânica

Este estudo teve com objetivo analisar a capacidade de um pino translúcido transmitir luz para o interior do canal radicular, bem como analisar o efeito desta polimerização na resistência mecânica e adesiva do conjunto pino, cimento, dente. Além disso, foi avaliada a resistência adesiva de diferentes tipos de cimentos resinosos. Foram utilizados 70 dentes humanos unirradiculares. O canal foi preparado com as fresas n°3 dos sistemas de pinos Light-Post (Bisco Inc, EUA). As raízes foram pintadas com esmalte preto para evitar a passagem de luz pela lateral do dente. Todos os dentes foram tratados com o sistema adesivo All Bond 2 (Bisco) e cimentados com três tipos de cimento formando os seguintes grupos: G1) Cimento Dual Duolink (Bisco) não fotopolimerizado, G2) Cimento Dual duolink fotopolimerizado, G3) Cimento Químico (C&B - Bisco) e G4) cimento fotopolimerizável (Illusion, Bisco). Cada grupo foi subdividido segundo a execução ou não de ciclagem mecânica. Em seguida, os dentes foram cortados perpendicular ao longo eixo do dente obtendo espécimes de 2mm de espessura. Cada secção era correspondente a uma região do dente (cervical, média, apical), possibilitando observar a polimerização do cimento nas diferentes profundidades da raiz realizando a analise Raman em três dentes de cada grupo. Em seguida, foi realizado o teste de push-out.Como resultado foi observado menor grau de conversão em direção apical para os cimentos foto-ativados, enquanto o cimento dual sem foto-ativaçao apresentou maiores valores. Para a resistência adesiva foi observada semelhança estatística inicial entre o cimento Duolink foto-ativado ou não, sendo que q ciclagem mecânica diminui consideravelmente a RA do Duolink quimicamente polimerizado. O cimento fotopolimerizável apresentou valores muito baixos de resistência adesiva e o cimento químico C&B apresentou os maiores valores antes e apos ciclagem mecânica.This study aimed to evaluate the light transmittance of a translucent post in the root canal, as well as the effects of light polymerization onto fatigue resistance and bond strengths at the post/cement/tooth joint. Moreover, the bond strengths obtained with different types of resin cement were determined. 70 human teeth were used. The root canals were prepared with Light Post drills (Bisco Inc, EUA) (size 3). Afterwards, the outer surface of each tooth was covered with black nail varnish to avoid passage of light through the root lateral walls. All teeth were treated with All Bond 2 (Bisco) bonding agent. They were divided into groups according to the resin cement: G1) non light-cured Duo-link dual-cure cement (Bisco), G2) light-cured Duo-link dual-cure cement, G3) C&B chemical-cure cement (Bisco) and G4) Illusion light-cure resin cement (Bisco). Each group was divided into subgroups, to designate the specimens subjected to mechanical cycling or not. Following that, the teeth were sectioned perpendicular to their long axis into 2mm sections. Each section corresponded to one of three study regions (cervical, middle and apical regions of the root canal preparation), allowing the determination of the degree of conversion at different levels of the root by using Raman spectroscopy in three teeth per group. Afterwards, the segments were subjected to Push-out bond strength test. The light-activated cements had the lowest degree of conversion towards the apical region whereas the dual-activated one presented the highest values. As for bond strength, the light- and non light-activated Duo-link groups were statistically similar in the beginning, but the mechanical cycling decreased the bond strength of the non light-activated group. The light-activated cement had the lowest bond strengths and the chemical cement (C&B) presented the highest bond strength values before and after mechanical cycling.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Comparison of resin push-out strength to root dentin of bovine- and human-teeth

Aim : To compare the push-out strength of bovine- and human-root dentin and, thus, evaluate the suitability of bovine-root dentin to substitute human-root dentin for bond strength testing. Materials and Methods : Ten single-rooted human-teeth and ten bovine incisors were prepared using a #3 bur of a fiber post system (12 mm long). The posts were duplicated with resin cement (Duolink). The root canals were treated with All Bond 2 adhesive system and the resin posts were cemented using Duolink. The specimens were cut perpendicular to their long axis, yielding disc-specimens with 1.5 mm thickness, which were submitted to a push-out test (1 mm/min). Ten bond strength values per group (n = 10) were used for statistical analysis (Student t test, a =.05). Results : Statistically significant differences were found for the bond strength values between bovine- (4.1 1.3 MPa) and human-root dentin (8.6 5.7 MPa) (P =.0001). Conclusion : The push-out strengths of bovine- and human-root dentin were statistically different

Comparison of resin push-out strength to root dentin of bovine- and human-teeth

Aim : To compare the push-out strength of bovine- and human-root dentin and, thus, evaluate the suitability of bovine-root dentin to substitute human-root dentin for bond strength testing. Materials and Methods : Ten single-rooted human-teeth and ten bovine incisors were prepared using a #3 bur of a fiber post system (12 mm long). The posts were duplicated with resin cement (Duolink). The root canals were treated with All Bond 2 adhesive system and the resin posts were cemented using Duolink. The specimens were cut perpendicular to their long axis, yielding disc-specimens with 1.5 mm thickness, which were submitted to a push-out test (1 mm/min). Ten bond strength values per group (n = 10) were used for statistical analysis (Student t test, a =.05). Results : Statistically significant differences were found for the bond strength values between bovine- (4.1 ± 1.3 MPa) and human-root dentin (8.6 ± 5.7 MPa) (P =.0001). Conclusion : The push-out strengths of bovine- and human-root dentin were statistically different

Optical Impression Systems for CAD-CAM Restorations

Computer-aided design/computer-aided manufacturing images can be taken through either direct or indirect imaging. For the indirect systems, the digitalization is obtained from the impression material or cast, and for the direct ones the image is taken directly from the mouth using intraoral scanners.The direct acquisition systems have been constantly improved because these are less invasive, quicker, and more precise than the conventional method. Besides, the digital images can be easily stored for a long time. Therefore, the aim of this paper was to describe and discuss based on the literature the main direct image acquisition systems available on the market: CEREC Bluecam (Sirona), Lava C.O.S. System (3M ESPE), iTero System (Cadent/Straumann), and E4D System (D4D Technologies)

Effects of mechanical cycling on the bonding of zirconia and fiber posts to human root dentin

Purpose: To evaluate the effect of cyclical mechanical loading on the bond strength of a fiber and a zirconia post bonded to root dentin.Materials and Methods: Forty single-rooted human teeth (maxillary incisors and canines) were sectioned, and the root canals were prepared at 12 mm. Twenty randomly seleced specimens received a quartz fiber post (FRC) (D.T. Light-Post) and 20 others received a zirconia post (ZR) (Cosmopost). The posts were resin luted (All Bond 2 + resin cement Duo-link) and each specimen was embedded in epoxy resin inside a PVC cylinder. Ten specimens with FRC post and 10 specimens with ZR post were submitted to fatigue testing (2,000,000 cycles; load: 50 N; angle of 45 degrees; frequency: 8 Hz), while the other 20 specimens were not fatigued. Thus, 4 groups were formed: G1: FRC+O cycles; G2: FRC+2,000,000 cycles; G3: ZR+O cycles; G4: ZR+2,000,000 cycles. Later, the specimens were cut perpendicular to their long axis to form 2-mm-thick disk-shaped samples (4 sections/specimen), which were submitted to the push-out test (1 mm/min). The mean bond strength values (MPa) were calculated for each tooth (n = 10) and data were submitted to statistical analysis (alpha = 0.05).Results: Two-way ANOVA revealed that the bond strength was significantly affected by mechanical cycling (p = 0.0014) and root post (p = 0.0325). The interaction was also statistically significant (p = 0.0010). Tukey's test showed that the mechanical cycling did not affect the bonding of FRC to root dentin, while fatigue impaired the bonding of zirconium to root dentin.Conclusion: (1) the bond strength of the FRC post to root dentin was not reduced after fatigue testing, whereas the bonding of the zirconia post was significantly affected by the fatigue. (2) Cyclical mechanical loading appears to damage the bond strength of the rigid post only

Surface conditioning of a composite used for inlay/onlay restorations: Effect on μTBS to resin cement

Purpose: To assess the effect of the composite surface conditioning on the microtensile bond strength of a resin cement to a composite used for inlay/onlay restorations. Materials and Methods: Forty-two blocks (6 × 6 × 4 mm) of a microfilled composite (Vita VMLC) were produced and divided into 3 groups (N = 14) by composite surface conditioning methods: Gr1 - etching with 37% phosphoric acid, washing, drying, silanization; Gr2 - air abrasion with 50-l̀m Al2O3 particles, silanization; Gr3 - chairside tribochemical silica coating (CoJet System), silanization. Single-Bond (one-step adhesive) was applied on the conditioned surfaces and the two resin blocks treated with the same method were cemented using RelyX ARC (dual-curing resin cement). The specimens were stored for 7 days in water at 37°C and then sectioned to produce nontrimmed beam samples, which were submitted to microtensile bond strength testing (μTBS). For statistical analysis (one-way ANOVA and Tukey's test, · = 0.05), the means of the beam samples from each luted specimen were calculated (n = 7). Results: μTBS values (MPa) of Gr2 (62.0 ± 3.9a) and Gr3 (60.5 ± 7.9a) were statistically similar to each other and higher than Gr1 (38.2 ± 8.9b). The analysis of the fractured surfaces revealed that all failures occurred at the adhesive zone. Conclusion: Conditioning methods with 50-l̀m Al2O3 or tribochemical silica coating allowed bonding between resin and composite that was statistically similar and stronger than conditioning with acid etching

Evaluation of the flexural strength of carbon fiber-, quartz fiber-, and glass fiber-based posts

This study investigated the flexural strength of eight fiber posts (one carbon fiber, one carbon/quartz fiber, one opaque quartz fiber, two translucent quartz fiber, and three glass fiber posts). Eighty fiber posts were used and divided into eight groups (n = 10): G1: C-POST (Bisco); G2: ÆSTHETI-POST (Bisco); G3: ÆSTHETI-PLUS (Bisco); G4: LIGHT-POST (Bisco); G5: D.T. LIGHT-POST (Bisco); G6: PARAPOST WHITE (Coltene); G7: FIBERKOR (Pentron); G8: REFORPOST (Angelus). All of the samples were tested using the three-point bending test. The averages obtained were submitted to the ANOVA and to Tukey's test (p < 0.05). The mean values (MPa) of the groups ÆSTHETI-POST - carbon/ quartz fiber post (Bisco) and ÆSTHETI-PLUS - quartz fiber post (Bisco) were statistically similar and higher than the mean values of the other groups. The mean values of the groups C-POST - carbon fiber post (Bisco), LIGHT-POST - translucent quartz fiber post (Bisco), D.T. LIGHT-POST - double tapered translucent quartz fiber post (Bisco), PARAPOST WHITE - glass fiber post (Coltene) and FIBREKOR - glass fiber post (Pentron) were similar and higher than the group REFORPOST - glass fiber post (Angelus). Copyright © 2005 by the American Association of Endodontists

Effect of surface conditioning methods on the microtensile bond strength of resin composite to composite after aging conditions

Objectives. This study evaluated the effect of two different surface conditioning methods on the repair bond strength of a bis-GMA-adduct/bis-EMA/TEGDMA based resin composite after three aging conditions. Methods. Thirty-six composite resin blocks (Esthet X, Dentsply) were prepared (5 mm x 6 mm x 6 mm) and randomly assigned into three groups for aging process: (a) immersion in citric acid (pH 3.0 at 37 degrees C, 1 week) (CA); (b) boiling in water for 8h (BW) and (c) thermocycling (x5000, 5-55 degrees C, dwell time: 30s) (TC). After aging, the blocks were assigned to one of the following surface conditioning methods: (1) silica coating (30 mu m SiOx) (CoJet, 3M ESPE) + silane (ESPE-Sil) (CJ), (2) phosphoric acid + adhesive resin (Single Bond, 3M ESPE) (PA). Resin composite (Esthet.X (R)) was bonded to the conditioned substrates incrementally and light polymerized. The experimental groups formed were as follows: Gr1:CA + PA; Gr2:CA + CJ Gr3:BW + PA; Gr4: BW + CJ; Gr5:TC + PA; Gr6: TC + CJ. The specimens were sectioned in two axes (x and y) with a diamond disc under coolant irrigation in order to obtain non-trimmed bar specimens (sticks, 10 mm x 1 mm x 1 mm) with 1 mm(2) of bonding area. The microtensile test was accomplished in a universal testing machine (crosshead speed: 0.5 mm min(-1)). Results. The means and standard deviations of bond strength (MPa +/- S.D.) per group were as follows: Gr1: 25.5 +/- 10.3; Gr2: 46.3 +/- 10.1; Gr3: 21.7 +/- 7.1; Gr4: 52.3 +/- 15.1; GrS: 16.1 +/- 5.1; Gr6, 49.6 +/- 13.5. The silica coated groups showed significantly higher mean bond values after all three aging conditions (p <0.0001) (two-way ANOVA and Tukey tests, alpha = 0.05). The interaction effect revealed significant influence of TC aging on both silica coated and acid etched groups compared to the other aging methods (p <0.032). Citric acid was the least aggressive aging medium. Significance. Chairside silica coating and silanization provided higher resin-resin bond strength values compared to acid etching with phosphoric acid followed by adhesive resin applications. Thermocycling the composite substrates resulted in the lowest repair bond strength compared to citric acid challenge or boiling in water. (C) 2006 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved

Effect of post length on the fatigue resistance of bovine teeth restored with bonded fiber posts: A pilot study

This study evaluated the influence of the cementation length of glass fiber-reinforced composite (FRC) on the fatigue resistance of bovine teeth restored with an adhesively cemented FRC. Thirty roots of single-rooted bovine teeth were allocated to 3 groups (n = 10), according to the ratio of crown length/root length (post cementation length): group 1 = 2/3, group 2 = 1/2, and group 3 = 1/1. The roots were prepared, the fiber posts (FRC Postec Plus) were cemented, and the specimens were submitted to 2 million mechanical cycles. After fatigue testing, a score was given based on the number of fatigue cycles until fracture, and data were submitted to statistical analysis. All specimens were resistant to fatigue. Taking into account the methodology and results of this study, the evaluated fiber posts can be cemented based on the ratio of crown/root at 1/1. Further clinical studies must be conducted to verify this ratio