Toothbrushing effects on the surface roughness and cement volume loss of bonded enamel-ceramic interface

Abstract This study evaluated the effect of toothbrushing on enamel-cementing material-ceramic bonded interfaces, using different cementing materials. Materials and Methods: Thirty enamel and thirty ceramic blocks were bonded with cementing materials to produce the samples that were bonded with three types of cementing materials: 1- RelyX Ultimate resin cement (REXU), 2- RelyX Unicem 2 self-adhesive resin cement (REU2) and 3- heated Z100 restorative composite (60°C). Bonded interfaces of the samples were toothbrushed and the surfaces of the 3 cementing materials were evaluated for roughness (RG, in µm), roughness profile (RP, in µm), and volume loss (VL, in µm3) (baseline and after 20,000 and 60,000 toothbrushing cycles). Data were evaluated by Generalized Linear Analysis (two factors: "material" and "toothbrushing cycle") and Bonferroni test (α=0.05). Results: REXU and Z100 exhibited lower RG than that presented by REU2, except after 60,000 toothbrushing cycles when only Z100 differed from REU2. The increase in toothbrushing cycles increased the RG and RP for all materials. REU2 also showed higher RP than those showed by REXU and Z100 when it was analyzed regarding the enamel. The VL of Z100 was the lowest with 20,000 toothbrushing cycles, regarding the enamel and ceramic. For 60,000 cycles, REXU showed the lowest VL regarding the ceramic, and REU2 had the highest VL regarding the enamel and ceramic. Conclusion: In general, REXU and Z100 showed the best results regarding the evaluations performed and the REU2 exhibited the highest RG, RP, and VL.

Resumo Este estudo avaliou o efeito da escovação nas interfaces de união esmalte-material cimentante-cerâmica, utilizando diferentes materiais cimentantes. Materiais e Métodos: Trinta esmaltes e trinta blocos cerâmicos foram unidos com materiais de cimentação para produzir as amostras que foram unidas com três tipos de materiais de cimentação: 1- cimento resinoso RelyX Ultimate (REXU), 2- cimento resinoso autoadesivo RelyX Unicem 2 (REU2) e 3-compósito restaurador aquecido Z100 (60°C). As interfaces coladas das amostras foram escovadas e as superfícies dos 3 materiais cimentantes foram avaliadas quanto à rugosidade (RG, em µm), perfil de rugosidade (RP, em µm) e perda de volume (VL, em µm3) (baseline e após 20.000 e 60.000 ciclos de escovação). Os dados foram avaliados por Análise Linear Generalizada (dois fatores: "material" e "ciclo de escovação") e teste de Bonferroni (α=0,05). Resultados: REXU e Z100 apresentaram menor RG do que REU2, exceto após 60.000 ciclos de escovação, quando Z100 diferiu apenas de REU2. O aumento dos ciclos de escovação aumentou o RG e RP para todos os materiais. O REU2 também apresentou PR maior que o REXU e Z100, quando analisado em relação ao esmalte. O VL de Z100 foi o menor com 20.000 ciclos de escovação em relação ao esmalte e cerâmica. Para 60.000 ciclos, o REXU apresentou o menor VL em relação à cerâmica e o REU2 o maior VL em relação ao esmalte e à cerâmica. Conclusão: De maneira geral, REXU e Z100 apresentaram os melhores resultados nas avaliações realizadas e o REU2 apresentou os maiores RG, RP e VL..

CO2 laser for dental alumina ceramic framework welding / O laser de CO2 para a soldagem de infraestruturas cerâmicas de alumina

Objective: Despite the increase of all-ceramic prosthesis in dental practice there is no evidence of the possibility of welding these structures if necessary. The objective of this study was to use CO2 laser (λ = 10.6 µm) as a welding agent to fuse dental polycrystalline alumina ceramic. Methods: Ceramic blocks of pre-sintered alumina were sectioned into 20 bars (10.0 x 1.5 x 1.5 mm) and sintered to the final cross section dimension of 1.2 x 1.2mm. The bars were adapted to an LHPG (Laser Heated Pedestal Growth) system device where the bars could be fixed in pairs and have their ends irradiated with CO2 laser to fusion. The ring-shaped laser beam (300 µm thickness) was directed with the aid of mirrors to reach samples' ends. The laser was continuously applied (40 W nominal power, 5 seconds). After welding, the samples were analyzed in stereomicroscope and SEM. A diffraction analysis was carried out with one sample. Results: CO2 laser was able to fuse the ceramic bars, but some of them showed some shape distortion in the fusion zone. The aspect of the fused alumina differed in color and translucency from the original sintered material. SEM evidenced the presence of porosity and voids in the center of the fusion zone. X-ray diffraction pointed to a reduction in crystallite size by two to four times in the welded region of samples. Conclusions: This study points to CO2 laser as a possible welding agent to polycrystalline alumina dental ceramic. Porosity observed in the molten zone gives cause for concern regarding weld resistance. (AU)

Objetivo: Apesar do aumento no número de próteses totalmente cerâmicas na prática clínica, não há evidência da possibilidade de se soldar essas estruturas se necessário. Este estudo testou o laser de CO2 (λ=10.6 µm) como um agente de solda para estruturas cerâmicas de alumina policristalina. Métodos: Blocos cerâmicos de alumina pré-sinterizada foram seccionados na forma de barras (10,0 x 1,5 x 1,5 mm) e sinterizados na dimensão final de 1,2 x 1,2 mm. As barras foram adaptadas a um sistema de crescimento de fibras cerâmicas (LHPG ­ Laser Heated Pedestal Growth) onde as barras foram fixadas em pares e tiveram suas extremidades irradiadas com laser de CO2 até a sua fusão. O feixe de laser foi direcionado com a ajuda de espelhos para atingir as extremidades das barras. O laser foi aplicado de forma contínua (40 W de potência nominal, 5 segundos). Depois da solda, os espécimes foram analisados em estereomicroscopia e MEV. Teste de difração foi conduzido com um espécime. Resutados: O laser de CO2 foi capaz de fundir as barras cerâmicas, mas algumas delas mostraram uma distorção da forma na zona de fusão. O aspecto da alumina soldada diferiu em cor e translucidez do material original. O MEV evidenciou a presença de porosidade no centro da zona de fusão. A difração por raio-x apontou para uma redução no tamanho dos cristalitos de duas a quatro vezes na região da solda. Conclusões: Esse estudo mostrou ser possível usar o laser de CO2 como um agente de solda para uma cerâmica policristalina de alumina. A porosidade observada na zona de fusão traz preocupação quanto à resistência da solda. (AU)

A study on the processing of dental ceramic composites by using laser / 대한치과보철학회지

PURPOSE: The laser processability of dental prosthesis is investigated using two ceramic composites, including 3M, Lava Ultimate and Ivoclar vivadent, IPS e.max. MATERIALS AND METHODS: The CO₂ laser, picosecond laser and femtosecond laser are used to assess the processing power of dental prosthetic materials Lava Ultimate and IPS e.max and the line processing shape was measured using a confocal microscope. RESULTS: The brittleness, carbonization and micro crack of the ceramic composite were influenced by heat accumulation of the material and could be controlled by the laser power and pulse time. CONCLUSION: In the case of CO₂ lasers, micro crack and carbonation occurred immediately, and in the picosecond laser processing, the micro cracks are partially improved, but the carbonization occurs continuously. Finally, we confirmed the high efficiency of laser processing with femtosecond laser. In particular, Lava Ultimate, a ceramic resin composite material, showed the best processability when processed using a femtosecond laser.

Effect of conventional and microwave glazing on surface roughness of metal ceramics: An atomic force microscopy analysis

This study investigated and compared the surface roughness achieved by glazing porcelain samples in a conventional and a microwave oven. Materials and Methods: Two commercial brands of metal ceramics were used, VITA VMK MASTER and IPS CLASSIC. Sixty samples were fabricated, 30 for each type of ceramic. The samples were sintered in the conventional oven and hand-polished to remove any irregularities. Samples (n = 10) from each type of ceramic were further divided into three groups as follows: hand-polished (Group A), conventional oven glazed (Group B), and microwave glazed (Group C). Each specimen was evaluated for surface roughness by atomic force microscope. Data were statistically analyzed using two-way analysis of variance (ANOVA) and Tukey's post hoc test (a = 0.05). Results: Two-way ANOVA indicated a highly significant difference in surface roughness based on the type of glazing (P < 0.001), there was a significant difference based on the metal ceramics (P = 0.002). There was also a significant interaction between the type of glazing and metal ceramics (P = 0.009). The images obtained from the atomic force microscope corroborated the measured values. Conclusions: All the results indicate that microwave glazing can be a feasible option for glazing porcelain specimens. It was concluded that surface topography is influenced by surface treatment and microwave glazed ceramic is superior to conventional oven glazed ceramic and hand-polishing showed greater surface roughness when compared to glazing. IPS CLASSIC ceramic showed relatively smooth surface when compared to VITA VMK MASTER irrespective of the surface treatment.

Characterization of Conventional and High-Translucency Y-TZP Dental Ceramics Submitted to Air Abrasion

Abstract This study evaluated the effect of air-abrasion on t®m phase transformation, roughness, topography and the elemental composition of three Y-TZP (Yttria-stabilized tetragonal zirconia polycrystal) dental ceramics: two conventional (Lava Frame and IPS ZirCad) and one with high-translucency (Lava Plus). Plates obtained from sintered blocks of each ceramic were divided into four groups: AS (as-sintered); 30 (air-abrasion with 30 mm Si-coated Al2O3 particles); 50 (air-abrasion with 50 mm Al2O3 particles) and 150 (air-abrasion with 150 mm Al2O3 particles). After the treatments, the plates were submitted to X-ray diffractometry; 3-D profilometry and SEM/EDS. The AS surfaces were composed of Zr and t phases. All treatments produced t®m phase transformation in the ceramics. The diameter of air-abrasion particles influenced the roughness (150>50>30>AS) and the topography. SEM analysis showed that the three treatments produced groove-shaped microretentions on the ceramic surfaces, which increased with the diameter of air-abrasion particles. EDS showed a decrease in Zr content along with the emergence of O and Al elements after air-abrasion. Presence of Si was also detected on the plates air-abraded with 30 mm Si-coated Al2O3 particles. It was concluded that irrespective of the type and diameter of the particles, air-abrasion produced t®m phase transformation, increased the roughness and changed the elemental composition of the three Y-TZP dental ceramics. Lava Plus also behaved similarly to the conventional Y-TZP ceramics, indicating that this high translucency ceramic could be more suitable to build monolithic ceramic restorations in the aesthetic restorative dentistry field.

Resumo Este estudo avaliou o efeito da abrasão a ar na transformação de fase t®m, na rugosidade, topografia e composição elementar de três cerâmicas Y-TZP (Zircônia tetragonal policristalina estabilizada por ítrio): duas convencionais (Lava Frame e ZirCad) e uma de alta translucidez (Lava Plus). Placas obtidas de blocos sinterizados de cada cerâmica foram divididos em quatro grupos: AS (pré-sinterizado); 30 (jateamento com partículas de Al2O3 de 30 mm cobertas com Si); 50 (jateamento com partículas de Al2O3 de 50 mm) e 150 (jateamento com partículas de Al2O3 de 150 mm). Após os tratamentos, as placas foram submetidas à difratometria de Rx, perfilometria 3-D e microscopia eletrônica de varredura com espectroscopia de energia dispersiva de Rx (SEM/EDS). As superfícies pré-sinterizadas apresentaram predominantemente Zr e fase tetragonal. Todos os tratamentos superficiais produziram transformação t®m nas cerâmicas avaliadas. A topografia e a rugosidade foram influenciadas pelo diâmetro das partículas abrasivas (150>50>30>AS). A análise através de SEM mostrou que os três tratamentos produziram fendas retentivas nas superfícies das cerâmicas, por influência do tamanho das partículas. A análise através de EDS mostrou uma diminuição da concentração de Zr, paralela ao surgimento de O e Al, após o jateamento. No grupo tratado com partículas de Al2O3 de 30 mm cobertas com Si foi também observado um aumento de Si após o jateamento. Concluiu-se que, independente do tipo e do diâmetro das partículas, o jateamento produziu transformação t®m, aumentou a rugosidade e alterou a composição elementar das cerâmicas avaliadas. A Lava Plus apresentou comportamento semelhante às cerâmicas convencionais, indicando que esta cerâmica de alta translucidez pode ser mais adequada à confecção de restaurações monolíticas no campo da odontologia estética restauradora.

Avaliação da resistência ao cisalhamento e do índice de remanescente adesivo de bráquetes colados em superfície de porcelana / Assessment of shear bond strength and adhesive remnant index of brackets bonded to porcelain surfaces

O aumento no número de pacientes adultos tem trazido desafios para os ortodontistas que, eventualmente, se deparam com a necessidade de colar bráquetes em superfície de porcelana. O objetivo do presente estudo foi avaliar a resistência de adesão e o índice de remanescente adesivo de bráquetes colados em superfície de porcelana e determinar quais os protocolos apresentam melhor resistência de união para o uso clínico. Foram produzidos 40 corpos de prova, reproduzindo a superfície vestibular de um incisivo central superior e, posteriormente, divididos em 4 grupos, aplicando os seguintes protocolos: Grupo I: Asperização da superfície com broca, ácido fluorídrico a 10%, silano e resina; Grupo II: Asperização com broca, aplicação de ácido fluorídrico a 10%, adesivo e resina; Grupo III: Aplicação de ácido fluorídrico a 10%, silano e resina e Grupo IV: Asperização com broca, aplicação de ácido fosfórico a 37%, silano e resina. Os corpos de prova foram submetidos ao teste de cisalhamento em uma máquina de ensaio universal. Após a descolagem dos acessórios, o índice de remanescente adesivo (IRA) foi determinado utilizando uma lupa estereoscópica e a superfície dos corpos de prova foi avaliada no MEV. De acordo com os resultados obtidos, verificou-se que não houve diferença estatisticamente significante entre os protocolos testados para colagem em porcelana. Com relação ao índice de remanescente adesivo, também não houve diferença estatisticamente significante. Concluiu-se que todos os protocolos apresentaram resistência de união ao cisalhamento compatível para uso clínico...

The widespread increase in the number of adult patients has posed daunting challenges for orthodontists, who are occasionally faced with the need to bond brackets to porcelain surfaces. The aim of this study was to evaluate the shear bond strength and adhesive remnant index of brackets bonded to porcelain surfaces, and determine what protocols offer a better bond strength in clinical practice. Forty specimens were fabricated reproducing the labial surface of a maxillary central incisor and then divided into 4 groups by applying the following protocols: Group I: Surface roughening with a drill, hydrofluoric acid at 10%, silane and resin; Group II: Surface roughening with a drill, application of hydrofluoric acid at 10%, orthodontic adhesive and resin; Group III: Application of hydrofluoric acid at 10%, silane and resin; and Group IV: Surface roughening with a drill, application of phosphoric acid at 37%, silane and resin. The samples were subjected to shear bond strength tests with a universal testing machine. After bracket removal, the adhesive remnant index (ARI) was determined using a stereoscopic microscope, and the surface of the specimens was evaluated with SEM. The results disclosed no statistically significant difference between the protocols tested for bonding to porcelain. There was no statistically significant difference in the adhesive remnant index. It was concluded that all protocols presented adequate shear bond strength for clinical use...

Performance of different polishing techniques for Vita ceramic restorations / 实用口腔医学杂志

Objective:To compare the effects of different polishing techniques on the surface roughness of ceramic surfaces,provi-ding reference to restoration polishing in clinic.Methods:70 disc-shaped ceramic specimens were randomly divided into 7 groups(n=10).The glazing treated samples were served as the controls(group 1),the rest samples were treated by white aluminum oxide stone only(group 2)or followed by the polishing head of Ceramiste(group 3),Ceramiste and Ceramaster(group 4),Komer porcelain (group 5),Komer zirconium oxide(group 6)and EVE zirconium oxide,respectively.Roughness of the ceramic samples(including Ra,Rz and Rp)was measured with surface profilometry after different process and the data were analyzed by one way ANOVA.The surface characteristics of the specimens were observed by scanning electron microscopy.Results:The Ra and Rp of group 2 and 3 was higher than those of group 1(P <0.05).The Rz of group 2,3,4 and 5 was higher than that of group 1(P <0.05).Conclusion:Polishers interspersed with diamond grit may achieve a finish equal in smoothness to the glazed surface.

Preparation and property analysis of a novel dental lithium disilicate glass-ceramic / 实用口腔医学杂志

Objective:To prepare a novel dental lithium disilicate glass-ceramic,and to study its properties.Methods:A2 colored novel glass-ceramic was prepared by sintering technique.The flexural strength,density,elastic modulus,hardness,fracture toughness, translucency and microstructure of the novel glass-ceramic and IPS e.max Press (LT A2,MO1 and HO1 )ceramic ingots were studied. Results:The novel glass-ceramic demonstrated a lower flexural strength (31 5 MPa)than MO ceramic ingot(338 MPa)(P 0.05).The translu-cency parameter of the novel glass-ceramic(21 .2)was higher than that of HO(1 6.5)but lower than that of LT(27.8)and MO(27.5) ceramic ingots(P <0.05).SEMimages showed an interlocking microstructure of rod-shaped Li2 Si2 O5 crystals in all the glass-ceramics investigated.Conclusion:The mechanical properties,translucency and microstructure of the novel glass-ceramic are similar to those of IPS e.max Press ceramic ingots,which can meet the requirements of clinical application.

The effect of repeated firings on the color change of dental ceramics using different glazing methods

PURPOSE: Surface color is one of the main criteria to obtain an ideal esthetic. Many factors such as the type of the material, surface specifications, number of firings, firing temperature and thickness of the porcelain are all important to provide an unchanged surface color in dental ceramics. The aim of this study was to evaluate the color changes in dental ceramics according to the material type and glazing methods, during the multiple firings. MATERIALS AND METHODS: Three different types of dental ceramics (IPS Classical metal ceramic, Empress Esthetic and Empress 2 ceramics) were used in the study. Porcelains were evaluated under five main groups according to glaze and natural glaze methods. Color changes (DeltaE) and changes in color parameters (DeltaL, Deltaa, Deltab) were determined using colorimeter during the control, the first, third, fifth, and seventh firings. The statistical analysis of the results was performed using ANOVA and Tukey test. RESULTS: The color changes which occurred upon material-method-firing interaction were statistically significant (P<.05). DeltaE, DeltaL, Deltaa and Deltab values also demonstrated a negative trend. The MC-G group was less affected in terms of color changes compared to other groups. In all-ceramic specimens, the surface color was significantly affected by multiple firings. CONCLUSION: Firing detrimentally affected the structure of the porcelain surface and hence caused fading of the color and prominence of yellow and red characters. Compressible all-ceramics were remarkably affected by repeated firings due to their crystalline structure.

Curing efficiency of various resin-based materials polymerized through different ceramic thicknesses and curing time

PURPOSE: The aim of this in vitro study was to examine the curing efficiency of various resin-based materials polymerized through ceramic restorations with 3 different thicknesses. Curing efficiency was evaluated by determining the surface microhardness (VHN) of the resin specimens. MATERIALS AND METHODS: Four kinds of resin materials were used. Z350 (3M ESPE Filtek(TM) Z350: A2 Shade), Z250 (3M ESPE Filtek(TM) Z250: A2 Shade) and Variolink(R) II (VL: Ivoclar vivadent, base: transparent) either with or without a self-curing catalyst (VLC: Ivoclar vivadent, catalyst: low viscosity/transparent) were filled into the silicone mold (10 mm diameter, 1 mm thick). They were cured through ceramic discs (IPS e.max Press MO-0 ingot ivoclar vivadent, 10 mm diameter, 0.5, 1 and 2 mm thicknesses) by LED light-curing units for 20 and 40 seconds. Vicker's microhardness numbers (VHNs) were measured on the bottom surfaces by a microhardness tester. Data were analyzed using a 3- way analysis of variance (ANOVA) at a significance level of 0.05. RESULTS: The thickness of ceramic disc increased, the VHNs of all four resin types were decreased (P<.05). The mean VHN values of the resins light cured for 40 seconds were significantly higher than that of LED for 20 seconds in all four resin materials (P<.05). VLC showed significantly higher VHN values than VL regardless of other conditions (P<.05). Z350 and Z250 showed higher values than VL or VLC (P<.01). CONCLUSION: Thinner ceramic disc with increased curing time resulted higher VHN values of all resin materials. The use of a catalyst produced a greater hardness with all polymerization methods. Restorative resin materials (Z350, Z250) showed higher VHN values than resin cement materials (VL, VLC).

The influence of silane evaporation procedures on microtensile bond strength between a dental ceramic and a resin cement.

Aim: To assess the influence of silane evaporation procedures on bond strength between a dental ceramic and a chemically activated resin cement. Materials and Methods: Eighteen blocks (6 mm Χ 14 mm Χ 14 mm) of ceramic IPS Empress 2 were cemented (C and B) to composite resin (InTen-S) blocks using a chemical adhesive system (Lok). Six groups were analyzed, each with three blocks divided according to ceramic surface treatment: two control groups (no treatment, NT; 10% hydrofluoric acid plus silane Monobond-S dried at room temperature, HFS); the other four groups comprised different evaporation patterns (silane rinsed and dried at room temperature, SRT; silane rinsed in boiling water and dried as before, SBRT; silane rinsed with boiling water and heat dried at 50°C, SBH; silane dried at 50 ± 5°C, rinsed in boiling water and dried at room temperature, SHBRT). The cemented blocks were sectioned to obtain specimens for microtensile test 7 days after cementation and were stored in water for 30 days prior to testing. Fracture patterns were analyzed by optical and scanning electron microscopy. Statistics and Results: All blocks of NT debonded during sectioning. One way ANOVA tests showed higher bond strengths for HFS than for the other groups. SBRT and SBH were statistically similar, with higher bond strengths than SRT and SHBRT. Failures were 100% adhesive in SRT and SHBRT. Cohesive failures within the "adhesive zone" were detected in HFS (30%), SBRT (24%) and SBH (40%). Conclusion: Silane treatment enhanced bond strength in all conditions evaluated, showing best results with HF etching.

Dual resin cement knoop hardness after different activation modes through dental ceramics

This study investigated the influence of ceramic compositions on Knoop Hardness Number (KHN) immediately and 24 h after polymerization and the effect of activation modes on the KHN of a resin cement. Ten Panavia F 2.0 resin cement discs were activated either directly using curing light, or chemically without light, or through 1.2-thick ceramic discs. The following ceramics were evaluated: Duceram, Cergogold, IPS Empress, IPS Empress 2, Procera, Cercon, In Ceram Alumina and In Ceram Zirconia. The KHN was obtained immediately and after 24-h testing time. Two-way ANOVA and Tukey's test were performed for statistical analysis (p<0.05). Direct activation showed higher KHN than activation through ceramics and chemical activation for both immediate and 24-h post activation. The KHN for 24-h post activation time was higher than that of the immediate post activation time except for the direct activation mode. The glass and di-silicate based ceramics showed higher KHN than alumina- and zirconia-based ceramics, immediately and after 24-h. The reinforced and opaque ceramics had the lowest KHN. The ceramic composition resulted in light attenuation, lower polymerization and lower KHN, and the 24-h testing time promoted an improvement of KHN except for direct activation mode.

Este estudo investigou a influência de composições de cerâmica no número de dureza Knoop (KHN), imediatamente e 24 h após a polimerização; e o efeito de modos de ativação na KHN de um cimento resinoso. Dez discos de cimento resinoso Panavia F 2.0 foram ativados diretamente usando uma fonte de luz, ou quimicamente sem luz, ou através de discos de cerâmica com espessura de 1,2 mm. As cerâmicas avaliadas foram Duceram, Cergogold, IPS Empress, IPS Empress 2, Procera, Cercon, In Ceram Alumina e In Ceram Zirconia. O KHN foi obtido nos tempos imediatamente e após 24 h. Os testes ANOVA two-way e Tukey foram realizados para a análise estatística (p<0,05). A ativação direta apresentou maiores KHN que a ativação através das cerâmicas e ativação química, para ambos os tempos testados imediatamente e após 24 h. O KHN para o tempo de ativação testado após 24 h foi superior que o tempo imediatamente, exceto para o modo de ativação direto. As cerâmicas à base de vidro e di-silicato apresentaram KHN superiores que as cerâmicas à base de alumina e zircônia, imediatamente e após 24 h. As cerâmicas mais reforçadas e opacas resultaram um dos menores KHN. A composição da cerâmica resulta em atenuação de luz, menor polimerização e menor KHN; e o tempo de 24 h testado promove uma melhora no KHN, exceto para o modo de ativação direto.

Resistência à flexão de porcelanas feldspáticas convencionais processadas por injeção / Flexural strength of heat-pressing feldspathic porcelains

O objetivo deste estudo foi investigar o efeito do processamento por injeção (método da cera perdida) na resistência à flexão, em três pontos, de porcelanas feldspáticas convencionalmente obtidas por sinterização. Foram avaliadas as porcelanas Ceramco-2, Duceragold, Duceram-Plus, Excelsior, Omega-900, Symbio, Vitadur-Alpha e VMK-95. Como controle, foi também utilizada a porcelana Cergogold, fornecida na forma de pastilhas pré-sinterizadas e processada exclusivamente por injeção. Corpos de prova em forma de barra (n = 10), com dimensões de 25 × 5 × 2 mm (ISO-6872), foram confeccionados em matrizes metálicas e processados, por sinterização ou injeção, nas temperaturas de cocção indicadas pelos fabricantes. Os ensaios foram realizados em equipamento MTS-810 (Material Test System, EUA), com célula de carga de 10 kN e velocidade de 0,5 mm.min-1. Os resultados, submetidos à análise de variância (p menor ou igual a 0,05), mostraram que o processamento por injeção foi capaz de proporcionar maior resistência à fexão para as porcelanas Duceram-Plus, Excelsior, Omega-900, Symbio e VMK-95 (p < 0,001). Nessa mesma condição experimental, a porcelana Cergogold mostrou-se estatisticamente superior apenas à porcelana Vitadur-Alpha, sendo inferior à porcelana Omega-900 e semelhante às demais (p < 0,001). A resistência à fexão das porcelanas Ceramco-2, Duceragold e Vitadur-Alpha não foi influenciada pelo processo de obtenção (p < 0,001).

The aim of this study was to evaluate the effect of injection process, on the three-point flexural strength on feldspathic ceramic, fabricated by sintering technique. The ceramics evaluated were Duceragold, Duceram Plus, Excelsior, Omega 900, Symbio,Vitadur Alpha, VMK 95 and Ceramco 2. Cergogold, that the processing technique is based on a conventional injection moulding, was used for control. The bar-shaped specimens (n = 10) with the size of 25 × 5 × 2 mm (ISO-6872) were fabricated in a metal mould and processed by injection or sinterized, according to manufacturing specifcations. The fexural test was performed in a MTS 810 testing machine (Material Test System, USA), with a 10 kN load cell and a crosshead speed of 0.05 mm.min-1. The data (MPa) were subjected to analysis of variance (p less than or equal to 0.05), and showed that the injection processed enhance the flexural strength of Duceram-Plus, Excelsior, Omega-900, Symbio and VMK-95 (p < 0.001). In this experimental condition, the ceramic Cergogold showed high value than Vitadur-Alpha, was inferior to the ceramic Omega-900, but there were no signifcant difference with the others (p < 0.001). The flexural strength was not influenced by the processing method for the ceramics Ceramco-2, Duceragold and Vitadur-Alpha.

Effect of light-curing units, post-cured time and shade of resin cement on knoop hardness

The aim of this study was to evaluate the Knoop hardness after 15 min and 24 h of different shades of a dual-cured resin-based cement after indirect photoactivation (ceramic restoration) with 2 light-curing units (LCUs). The resin cement Variolink II (Ivoclar Vivadent) shade XL, A2, A3 and opaque were mixed with the catalyst paste and inserted into a black Teflon mold (5 mm diameter x 1 mm high). A transparent strip was placed over the mold and a ceramic disc (Duceram Plus, shade A3) was positioned over the resin cement. Light-activation was performed through the ceramic for 40 s using quartz-tungsten-halogen (QTH) (XL 2500; 3M ESPE) or light-emitting diode (LED) (Ultrablue Is, DMC) LCUs with power density of 615 and 610 mW/cm2, respectively. The Koop hardness was measured using a microhardness tester HMV 2 (Shimadzu) after 15 min or 24 h. Four indentations were made in each specimen. Data were subjected to ANOVA and Tukey's test (a=0.05). The QTH LCU provided significantly higher (p<0.05) KHN values than the LED LCU. When the post-cure times were compared for the same shade, QTH and LED at 24 h provided significantly higher (p<0.05) KHN values than at 15 min. It may be concluded that the Knoop hardness was generally dependent on the LCU and post-cure time. The opaque shade of the resin cement showed lower Knoop hardness than the other shades for both LCUs and post-cure times.

Este estudo avaliou a dureza Knoop após 15 min e 24 h de diferentes cores do cimento resinoso dual após fotoativação indireta com 2 fontes de luz. O cimento resinoso Variolink II (Ivoclar Vivadent) nas cores XL, A2, A3 e opaco foram misturados com a pasta catalisadora e inseridos dentro de um molde de teflon preto com (5 mm de diâmetro x 1 mm de espessura). A tira de poliéster transparente foi inserida sobre o molde e um disco da cerâmica (Duceram Plus, cor A3) foi posicionada sobre o cimento resinoso. A fotoativação foi realizada sobre o disco de cerâmica por 40 s usando a lâmpada de luz halógena (XL 2500, 3M ESPE) ou luz emitida por diodo (LED) com intensidade de luz de 615 e 610 mW/cm2. A dureza Knoop foi medida usando o microdurômetro HMV 2 (Shimadzu) com carga de 50 g por 15 s, após 15 min e 24 h. Quatro indentações foram feitas em cada amostra. Os dados foram submetidos à Análise de Variância e ao teste de Tukey (a=5 por cento). A fonte de luz halógena promoveu valores de dureza significantemente maiores (p<0,05) que o LED. Quando os tempos pós-polimerização foram comparados para a mesma cor, a luz halógena e o LED promoveram valores de dureza significantemente maiores (p<0,05) em 24 h do que aos 15 min. Pode-se concluir que, de maneira geral, a dureza Knoop foi dependente da fonte de luz e do tempo pós-polimerização. A cor opaca do cimento resinoso mostrou menores valores de dureza Knoop que as outras cores para ambas as fontes de luz e tempos pós-polimerização.

Comparison of the degree of conversion of light-cured resin cement in regard to porcelain laminate thickness, light source and curing time using FT-IR / 대한치과보철학회지

STATEMENT OF PROBLEM: The degree of light attenuation at the time of cementation of the PLV restoration depends on characteristics such as thickness, opacity and shade of the restorations, which interfere with light transmittance and, as a result, may decrease the total energy reaching the luting cement. PURPOSE: The purpose of this study was to compare the degree of conversion of light-cured resin cements measuring by FT-IR in regard to different thickness, light devices and curing time. MATERIAL AND METHODS: In the control group, a clear slide glass (1.0 mm) was positioned between the light cured resin cement and light source. The specimens of ceramics were made with IPS Empress Esthetic. The ceramics were fabricated with varying thicknesses-0.5, 1.0, 1.5 mm with shade ETC1. Rely X(TM) Veneer with shade A3, light-cured resin cement, was used. Light-activation was conducted through the ceramic using a quartz tungsten halogen curing unit, a light emitting diode curing unit and a plasma arc curing unit. The degree of conversion of the light-cured resin cement was evaluated using FT-IR and OMNIC. One-way ANOVA and Tukey HSD test were used for statistical analysis (alpha< .05). RESULTS: The degree of conversion (DC) of photopolymerization using QTH and LED was higher than results of using PAC in the control group. After polymerization using QTH and LED, the DC results from the different ceramic thickness- 0.5 mm, 1.0 mm, 1.5 mm- did not show a significant difference when compared with those of control group. However, the DC for polymerization using PAC in the 1.5mm ceramic group showed significantly lower DC than those of the control group and 0.5 mm ceramic group (P<.05). At 80 s and 160 s, the DC of light-cured resin cement beneath 1.0 mm ceramic using LED was significantly higher than at 20 s (P<.05). CONCLUSION: Within the limitation of this study, when adhering PLV to porcelain with a thickness between 0.5 - 1.5 mm, the use of PAC curing units were not considered however, light cured resin cements were effective when cured for over 40 seconds with QTH or LED curing units. Also, when curing the light cured resin cements with LED, the degree of polymerization was not proportional with the curing time. Curing exceeding a certain curing time, did not significantly affect the degree of polymerization.

Progress in carbon nanotube based dental ceramic material / 国际生物医学工程杂志

Carbon nantubes composites draws more and more attention these days. Its application provides new potential for the reinforcement and toughness of dental ceramic. In this paper, the properties of carbon nanotube, carbon nanotube based ceramic composites and its mechanics of toughness, and the future trend of carbon nanotube in dental ceramic material, have been reviewed.

The effects of heat-treatment on the flexible strength of a novel dental mica-glass-ceramic / 实用口腔医学杂志

Objective:In order to optimize the crystallization technics, the effects of heat-treatment on the flexible strength and microstructure of a novel dental mica glass-ceramic were studied in present study. Methods:7 groups were treated respectively with different crystallization temperature and different crystallization time.Then the flexible strength, X-ray diffraction (XRD)and scanning electron microscope(SEM) were used to study the flexible strength and microstructure of such a novel dental mica glass-ceramic. Results: The result of the study indicated that along with the rise of crystallizing temperature and crystallizing time, this dental mica glass-ceramic showed the peak of bending strength (173.68 MPa) at 680 ℃ for 120 min.Conclusion:This material is promising as esthetic all-ceramic dental material.

Color measurements of dental CAD/CAM alumina-galss-composites / 实用口腔医学杂志

Objective: To measure the color of dental CAD/CAM alumina-glass-composites(AGC). Methods: Dental CAD/CAM alumina block were infiltrated at 1 120 ℃ by laboratory made AG1,AG2,AG3 and AG4 color serials of infiltration glass powder and Vita In-Ceram Alumina AL1,AL2,AL3 and AL4 infiltration glass respectively. Specimens were made with the area of 10 mm?10 mm,thickness of 0.5,1 and 1.5 mm respectively. Color parameters were measured by Minolta CM-2600d spectrophotometer. Results:The specimen with the thickness of 1 mm was used as the standard for color measurement.After infiltration with AL1-AL4 glass powder,the color parameters of Vita alumina core ceramic were L*: 69.39-78.41,a*:1.82- 4.02,b*:18.35-24.42,when infiltrated with AG1-AG4 glass powder, the color parameters of CAD/CAM AGC were L*:68.80-78.44,a*:1.32- 4.75,b*:16.85- 21.86. b*value and chroma of the AG3 core ceramic were lower than that of AL3 core ceramic,while a* value was higher.b* value and chroma of the AG1 and AG2 core ceramic were lower than that of AL1 and AL2 core ceramic. The reflectance curve of CAD/CAM AGC infiltrated by AG1-AG4 glass powder demonstrated the similar trend as that of the core ceramic infiltrated by Vita In-Ceram glass powder. Conclusion: The color range and surface reflection rate of laboratory made AG1-AG4 AGC are similar with those of Vita AL1-AL4 In-Ceram Alumina core and may meet the need of color match with veneer ceramics.

Effects of different polishing and glazing methods on the ceramic surface / 实用口腔医学杂志

0.05).Conclusion:Different polishing and glazing methods have significant effects on the surface roughness of ceramics,while the surface gloss of ceramics is not affected.

The oral mucosa irritation test for colored alumina-glass composite / 解放军医学杂志

Objective To study the biosafety of colored alumina-glass composite by mucosa irritation test. Methods The colored alumina-glass composite and a non-irritating material were separately fixed to the oral mucosa of a mouse. The contact parts were examined with bare eye, histologically and cytologically. Results No obvious inflammation of the mucosa was detected in the site where colored alumina-glass composite was in contact. Conclusion Alumina-glass composite has good biosafety.