Failure behavior of zirconia crowns subjected to air abrasion with different particle sizes

Abstract This study aimed to investigate the failure behavior of 3 mol.% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) prosthetic crowns air-abraded with aluminum oxide (AO) particles of different sizes. Ninety ceramic premolar crowns were produced with 3Y-TZP frameworks veneered with porcelain. Crowns were randomly divided into three groups, according to the size of the air abrasion AO particles (n = 30): (GC) untreated (control); (G53) 53 µm; (G125) 125 µm. Air abrasion was performed with 0.25 mpa pressure, 10-mm distance, for 10 s. Crowns were adhesively cemented to dentin analog abutments. Specimens were loaded in compression to failure, in 37oC distilled water, using a universal testing machine (n = 30). Fractographic analysis was performed using a stereomicroscope and SEM. The roughness of the crown's inner surface was evaluated using an optical profilometer (n = 10). Fracture load data were statistically analyzed with Weibull analysis and roughness data with Kruskal-Wallis (α = 0.05). GC had the lowest characteristic fracture load (L0), while G53 and G125 had higher and statistically similar L0 values. The Weibull modulus (m) was similar among groups. The failure modes observed were catastrophic failure and porcelain chipping. There were no differences between the roughness parameters for the experimental groups (p > 0.05). The size of the AO particles did not affect the fracture load and failure mode of 3Y-TZP crowns. Air abrasion with 53 µm and 125 µm particles resulted in a higher fracture load of ceramic crowns than the untreated group while maintaining their reliability and surface characteristics.

Resumo O objetivo deste estudo foi investigar o efeito do jateamento com óxido de alumínio (AO) com diferentes tamanhos de partículas no comportamento de fratura de coroas protéticas de zircônia tetragonal estabilizada com 3 mol% de ítria (3Y-TZP). Noventa coroas cerâmicas de pré-molares foram produzidas com infraestruturas de 3Y-TZP recobertas com porcelana. As coroas foram divididas aleatoriamente em três grupos, de acordo com o tamanho das partículas de AO do jateamento (n = 30): (GC) não tratada (controle); (G53) 53 µm; (G125) 125 µm. O jateamento foi realizado com pressão de 0,25 MPa, distância de 10 mm, por 10 s. As coroas foram cimentadas adesivamente em pilares análogos à dentina. As coroas foram testadas em compressão até a falha, em água destilada a 37ºC, usando uma máquina universal de ensaios (n = 30). A análise fractográfica foi realizada usando estereomicroscópio e MEV. A rugosidade da superfície interna das coroas foi avaliada usando um perfilômetro óptico (n = 10). Os dados de carga de fratura foram analisados ​​estatisticamente com análise de Weibull e os dados de rugosidade com Kruskal-Wallis (( = 0,05). GC apresentou a menor carga característica de fratura (L0), enquanto G53 e G125 apresentaram valores de L0 maiores e estatisticamente semelhantes. O módulo de Weibull (m) foi semelhante entre os grupos. Os modos de falha observados foram falha catastrófica e lascamento da porcelana. Não houve diferenças entre os parâmetros de rugosidade para os grupos experimentais (p > 0,05). O tamanho das partículas de AO não afetou a carga de fratura e o modo de falha das coroas 3Y-TZP. O jateamento com partículas de 53 µm e 125 µm resultou em maior carga de fratura das coroas cerâmicas do que o grupo não tratado, mantendo sua confiabilidade e características de superfície.

Effect of novel pre-sintered zirconia surface treatment on shear bond strength between zirconia and veneering porcelain compared to conventional surface treatments: an in-vitro study / Efeito de um novo tratamento de superfície de zircônia pré-sinterizada na resistência ao cisalhamento entre zircônia e porcelana em comparação com os tratamentos de superfície convencionais: estudo in vitro

Objective: to evaluate the effect of novel zirconia surface treatment method on shear bond strength between zirconia and veneering porcelain compared to air abrasion and CoJet surface treatment methods. Material and Methods: twenty-one zirconia ceramic discs were fabricated with diameter of 7mm and 3mm thickness and divided according to surface treatment into three subgroups, control group I: Air Abrasion (n=7), group II: CoJet (n=7) and group III: Z-etch (n=7). Porcelain was built over the zirconia specimens with a customized mold and fired in a ceramic furnace. All specimens were thermocycled (20000 cycles) between 5°C ­ 55 °C with a dwell time of 30 seconds in distilled water and shear bond strength of veneering porcelain to each zirconia specimen was tested using a universal testing machine. Results: numerical data were explored for normality by checking the distribution of data and using tests of normality (Kolmogorov-Smirnov and Shapiro-Wilk tests). One-way ANOVA test was used to compare between the groups. There was a statistically significant difference between the three groups (P-value = 0.002, Effect size = 0.503). Pair-wise comparisons between groups revealed that Z-etch showed the statistically significantly highest mean shear bond strength. Conclusion: zirconia coating using z-etch is showing promising results in promoting higher bond strength than conventional surface treatment methods as air abrasion and silica coating (AU)

Objetivo: avaliar o efeito do novo método de tratamento de superfície de zircônia na resistência ao cisalhamento entre a zircônia e a porcelana de cobertura em comparação com os métodos de abrasão a ar e jateamento com CoJet. Material e Métodos: vinte e um discos de zircônia foram confeccionados com diâmetro de 7mm e espessura de 3mm e divididos de acordo com o tratamento de superfície em três subgrupos, grupo controle I: Abrasão a ar (n=7), grupo II: CoJet (n=7) e grupo III: Z-etch (n=7). A porcelana foi aplicada sobre os espécimes de zircônia com um molde personalizado e sinterizada em forno de cerâmica. Todos os espécimes foram termociclados (20.000 ciclos) entre 5°C - 55°C com um tempo de permanência de 30 segundos em água destilada e a resistência ao cisalhamento da porcelana de cobertura foi testada através de uma máquina de ensaio universal. Resultados: os dados numéricos foram avaliados quanto à normalidade, verificando a distribuição dos dados e utilizando testes de normalidade (testes de Kolmogorov-Smirnov e Shapiro-Wilk). O teste ANOVA de um fator foi utilizado para comparar os grupos. Houve uma diferença estatisticamente significativa entre os três grupos (P-valor = 0,002, tamanho do efeito = 0,503). As comparações pareadas entre os grupos revelaram que o Z-etch apresentou a resistência de união ao cisalhamento estatisticamente significativamente mais alta. Conclusão: o revestimento de zircônia utilizando Z-etch mostrou resultados promissores para o aumento da resistência de união em comparação aos métodos convencionais de tratamento de superfície, como abrasão a ar e revestimento de sílica (AU)

Clinical Effectiveness of Composite Resin Bonded with Universal Adhesive for the Restoration of Non-Carious Cervical Lesions Using Air Abrasion: A Randomised Controlled Trial

ABSTRACT @#Restorative treatment is very challenging for non-carious cervical lesions (NCCLs) due to functional and structural complexities. The purpose of this randomised controlled trial (RCT) was to evaluate the clinical performance of nanocomposite restorations bonded using universal adhesive in self-etch mode with and without air abrasive surface treatment for NCCLs. A total of 70 NCCLs, from a group of consenting patients who fulfilled the inclusion criteria, were recruited for the study. The study was carried out following CONSORT guidelines. Block randomisation was done for equal allocation of lesions into; Group 1 (surface treatment with alumina air abrasion) and Group 2 (control group without mechanical surface treatment). The lesions were restored with nanocomposite using a universal bonding agent in self-etch mode. The clinical performance of the restorations was evaluated by two examiners using modified United States Public Health Service (USPHS) criteria at baseline, 3 months, 6 months and 12 months. A Chi-square test was performed for inter-group comparison. Cochran’s Q test and Dunn’s post hoc analysis were used for intra-group comparison. The inter-group comparison revealed no statistically significant difference between the experimental and control group for all the parameters assessed. With the intra-group analysis, it was found that there was a significant decrease in the performance of the restorations concerning marginal staining, marginal adaptation and surface texture during the evaluation period (p < 0.05). However, all of them demonstrated clinically acceptable performance. According to the results of this RCT, it was concluded that airborne particle abrasion of NCCLs did not improve the clinical performance of nanocomposite resin bonded using universal adhesive.

Surface treatment and adhesion approaches on polymer-infiltrated ceramic network: influence on the bond strength to resin cement

Aim: To evaluate the effect of different surface treatments and adhesive approaches on the microshear bond strength of resin cement to a polymer-infiltrated ceramic network (PICN). Methods: PICN blocks were randomly assigned into 9 groups (n=10): CTRL: no treatment; HF: 5% hydrofluoric acid etching; HF-S: HF + silane; HF-S-A: HF-S + adhesive (Adper Single Bond 2); HF-UA: HF + universal adhesive (Single Bond Universal); SB: sandblasting with 50 µm Al2O3 particles; SB-S: SB + silane; SB-S-A: SB-S + adhesive; SB-UA: SB + universal adhesive. Resin cement microcylinders (Ø = 0.96 mm; height = 1 mm) (RelyX Ultimate) were built upon the PICN surface after roughness and contact angle measurements. Next, microshear bonding tests (µSBS) were performed (0.5 mm/min) after water storage (37ºC, 90 days) and thermocycling (12,000 cycles; 5ºC-55ºC). Failure modes were observed under stereomicroscope. Bond strength data were analyzed by two-way ANOVA/Tukey's test and t-tests. Kruskal-Wallis/Dunn's tests were conducted for roughness and contact angle data (α = 0.05). Results: A rougher surface and lower contact angles were observed for Sandblasting. HF-S (18.54 ± 2.03 MPa), SB-S (19.00 ± 1.66 MPa) and SB-UA (18.07 ± 2.36 MPa) provided the highest bond strength values, followed by the other treated groups. The CTRL group resulted in lower bond strength (7.18 ± 2.34 MPa). Conclusion: Hydrofluoric acid etching followed by silane application and sandblasting followed by silane or universal adhesive are useful clinical steps to enhance bonding to PICN. Adhesive applications after HF etching have no advantages in bonding to PICN

Shear bond strength evaluation of metallic brackets bonded to a CAD/CAM PMMA material compared to traditional prosthetic temporary materials: an in vitro study

ABSTRACT Introduction: Orthodontic treatment for adults is currently increasing, and therefore the need to bond brackets to restorations and temporary crowns. The use of CAD/CAM PMMA provisional restorations for orthodontic purposes have not yet been described, and there is currently insufficient information regarding the strength of bracket adhesion. Objective: This study aimed at evaluating the effects of thermocycling (TC) and surface treatment on shear bond strength (SBS) of brackets to different provisional materials. Methods: Forty specimens were made from each material [PMMA (Telio Lab), bis-acryl (Telio CS C&B), and PMMA CAD/CAM (Telio CAD)], sandpapered, and divided according to surface treatment (pumiced or sandblasted) and TC (half of the samples = 1,000 cycles, 5°C/55°C water baths) (n = 10/group). Stainless-steel brackets were bonded to the specimens (using Transbond XT), and SBS testing was performed. Data were analyzed by three-way ANOVA and LSD post-hoc tests (α = 0.05). Failure types were classified with adhesive remnant index (ARI) scores. Results: SBS values ranged from 1.5 to 14.9 MPa. Sandblasted bis-acryl and sandblasted auto-curing PMMA groups presented similar values (p> 0.05), higher than the CAD/CAM material (p< 0.05), with or without TC. When thermocycled, pumiced bis-acryl showed higher SBS than pumiced acrylic (p= 0.005) and CAD/CAM materials (p= 0.000), with statistical difference (p= 0.009). TC showed negative effect (p< 0.05) for sandblasted bis-acryl and pumiced acrylic groups. ARI predominant score was mostly zero (0) for CAD/CAM, 1 and 2 for bis-acryl, and 1 for acrylic groups. Conclusion: In general, bis-acryl material showed the highest SBS values, followed by acrylic and CAD/CAM materials, which showed SBS values lower than an optimum strength for bonding brackets.

RESUMO Introdução: Atualmente, a demanda por tratamento ortodôntico em adultos tem aumentado. Consequentemente, também tem aumentado a necessidade de se colar braquetes em restaurações e coroas provisórias. O uso de restaurações provisórias de PMMA CAD/CAM com finalidade ortodôntica ainda não foi descrito e, até a presente data, não há informação suficiente sobre a resistência da colagem dos braquetes a esse tipo de material. Objetivo: O presente estudo teve como objetivo avaliar os efeitos da termociclagem (TC) e do tratamento de superfície sobre a resistência da colagem ao cisalhamento (RC) de braquetes colados em diferentes materiais provisórios. Métodos: Quarenta espécimes foram confeccionados de cada material: resina acrílica PMMA (Telio Lab), resina bisacrílica (Telio CS C&B), e PMMA CAD/CAM (Telio CAD). Em seguida, foram lixados e divididos de acordo com o tratamento de superfície (polidos ou jateados) e TC (metade da amostra - 1.000 ciclos de imersão em água a 5°C e 55°C) (n = 10/grupo). Braquetes de aço inoxidável foram colados aos espécimes (utilizando Transbond XT) e realizou-se o teste de RC. As informações foram analisadas por meio dos testes ANOVA de três vias e post-hoc LSD (α?#8197;= 0,05). Os tipos de falha foram classificados de acordo com os escores do índice de adesivo remanescente (ARI). Resultados: Os valores de RC variaram de 1,5 a 14,9 MPa. Os grupos de resina bisacrílica jateada e de PMMA autopolimerizável jateado apresentaram valores semelhantes (p> 0,05), superiores ao do material CAD/CAM (p< 0,05) com ou sem TC. Quando submetido à TC, o grupo de resina bisacrílica polida apresentou resistência ao cisalhamento maior do que os grupos de resina acrílica polida (p= 0,005) e do material CAD/CAM (p= 0,000), com diferença estatística (p= 0,009). A TC apresentou efeito negativo (p< 0,05) para os grupos de resina bisacrílica jateada e de resina acrílica polida. O escore ARI = 0 foi predominante para o grupo CAD/CAM; os escores 1 e 2, para o grupo resina bisacrílica; e o escore 1, para o grupo resina acrílica. Conclusão: De forma geral, a resina bisacrílica apresentou os maiores valores de RC, seguida da resina acrílica e do material CAD/CAM, que apresentaram valores de RC inferiores à força recomendada para colagem de braquetes.

Retention strength of ball-attachment titanium post for removable partial denture or overdenture

Aim: To evaluate the retention of an endodontic titanium postwith a spherical head for removable partial denture or overdentureattachment according to surface treatment type. Methods: Sixtyhealthy single-rooted teeth, sectioned at the enamel/cementumjunction, were treated endodontically and steadily fixed in theembedding acrylic resin. The titanium posts were subdivided intofour groups: control, no surface treatment (Ctrl); posts with macroretentivegrooves (MR); air abrasion of the post surface (AB); andposts with macro-retentive grooves and air abrasion of the postsurface (MR+AB). The posts were luted in the root canal usingself-adhesive dual resin cement. Pull-out testing was performedusing a universal testing machine until complete detachment wasachieved. After pull-out testing, the metallic posts were examinedunder an optical microscope and the failures were classifiedbased on the cement distribution pattern on the extracted posts:0, no cement left on the post (cement/post failure); 1, postsurface partially covered by adhered cement (post/cement anddentin/cement mixed failure); 2, post surface completely coveredby cement (dentin/cement failure). The retention data wereanalyzed by one-way ANOVA, Bonferroni­Dunn test (p<0.05)and Weibull analysis. Results: AB showed the highest retentionvalue (485.37±68.36), followed by MR+AB (355.80±118.47), MR(224.63±42.54) and Ctrl (113.12 ± 51.32). AB and MR showedthe highest Weibull moduli. Conclusions: The data indicatedthat air abrasion alone could significantly increase the retentionof titanium posts/attachments for use with overdentures orremovable partial denture

Influence of alumina air-abrasion for highly translucent partially stabilized zirconia on flexural strength, surface properties, and bond strength of resin cement

Abstract Objective This study aims to evaluate the influence of different air-abrasion pressures and subsequent heat treatment on the flexural strength, surface roughness, and crystallographic phases of highly translucent partially stabilized zirconia (Y-PSZ), and on the tensile bond strength of resin cement to Y-PSZ. Methodology Fully sintered zirconia specimens were ground with SiC paper (control) and/or air-abraded with 50 µm particles of alumina at 0.1, 0.15, 0.2, or 0.3 MPa or left as-sintered. After air-abrasion at 0.2 MPa (0.2AB), additional specimens were then heated to 1500°C, and held for one hour at this temperature (0.2AB+HT1h). Flexural strength and surface roughness were evaluated. Crystalline phase identification was also carried out using X-ray diffraction. Bonded zirconia specimens with self-adhesive resin cement were stored in distilled water at 37°C for 24 h, either with or without aging (thermal cycling 4-60°C/20000). Results were analyzed statistically by ANOVA and Tukey-Kramer tests. Results The flexural strength decreased with the increase in air-abrasion pressure, while in contrast, the surface roughness increased. The lowest flexural strength and the highest roughness value were found for the 0.2AB and 0.3AB groups, respectively. All groups contained cubic-, tetragonal ( t )-, and rhombohedral ( r )-ZrO2 phases with the exception of the as-sintered group. Upon increasing the air-abrasion pressure, the relative amount of the r -ZrO2 phase increased, with a significant amount of r -ZrO2 phase being detected for the 0.2AB and 0.3AB groups. The 0.2AB+HT1h group exhibited a similar flexural strength and t -ZrO2 phase content as the as-sintered group. However, the 0.2AB group showed a significantly higher tensile bond strength (p<0.05) than the 0.2AB+HT1h group before and after aging. Conclusion Micromechanical retention by alumina air-abrasion at 0.2 MPa, in combination with chemical bonding of a resin to highly translucent Y-PSZ using a MDP-containing resin cement may enable durable bonding.

A new approach for Y-TZP surface treatment: evaluations of roughness and bond strength to resin cemen

Abstract Objective This study aims to evaluate the effect of sonochemical treatment on the surface of yttria-stabilized tetragonal zirconia (Y-TZP) before and after the final sintering. Material and Methods Twenty-eight Y-TZP discs were divided into four groups (n=7), according to surface treatment: PRE: pre-sintering sonication with 30% nominal power for 15 min; POS: post-sintering sonication with 30% nominal power for 15 min; JAT: air abrasion with 50-μm alumina particles; and CON: control group with no treatment. The POS and JAT groups were sintered before sonication and the PRE group after sonication. Surface roughness was analyzed using confocal microscopy, after which resin cement cylinders were placed on the surface of the Y-TZP discs and subjected to mechanical microshear bond strength test until fracture. Surface roughness and microshear bond strength values underwent ANOVA and the Tukey tests. Results The surface roughness values for the PRE group (299.91 nm) and the POS group (291.23 nm) were not significantly different (p≥0.05), statistically, and the surface roughness value of the JAT group (925.21 nm) was higher than those of PRE and POS (p=0.007) groups. The mechanical microshear bond strength test showed that there was no statistically significant difference between the groups (p=0.08). Conclusions Therefore, the results showed that sonochemical treatment modifies the Y-TZP surface and is similar to the well-established sandblasting surface treatment regarding the strength of the bond with the resin cement.

Desgaste del esmalte por diferentes tratamientos químicos y mecánicos / Wear of the enamel by different chemical and mechanical treatments / Desgaste do esmalte por diferentes tratamentos químicos e mecânicos

Introducción: La microabrasión se describe como un procedimiento realizado sobre el esmalte dental en el cual mediante la utilización de un agente ácido y un agente abrasivo se logra corregir alteraciones cromáticas superficiales. Algunos estudios demuestran como los parámetros de tiempo, número de aplicaciones y la presión ejercida, influyen en la can-tidad de esmalte eliminado. Objetivo: Establecer el espesor de esmalte dental eliminado según la capacidad abrasiva de 9 tratamientos químico mecánicos, mediante estereomicroscopia. Materiales y métodos: Con el aval del comité de ética de la Facultad de Odontología de la Universidad Nacional de Colombia, se recolectaron 90 terceros molares bajo consentimiento informado y se mantuvieron almacenados bajo los parámetros de la norma ISO 11405. Sobre bloques de acrílico se fijaron las mitades linguales de las coronas dentales, creando sobre ellas superficies planas mediante serie de lijas con irrigación y tomando impresiones con silicona de adición. Se distribuyeron de forma aleatoria en 9 grupos (n 10). Cada grupo recibió un tratamiento por un periodo de 30 segundos: G1: Opalustre® (Ultradent), G2: Piedra pómez y ácido fosfórico al 37% (Ultra-Etch®, Ultradent), G3: Piedra pómez, glicerina y ácido fosfórico al 37% (Ultra-Etch®, Ultradent), G4: Fresas de halo amarillo (Komet), G5: Fresas de halo blanco (Komet), G6: Discos Sof-Lex® (3M), color amarillo, G7: Discos Sof-Lex® (3M), color amarillo y amarillo claro, G8: Arenado, y G9: Puntas ultrasónicas Perfect Margin (Acteon). El espesor de desgaste creado fue medido utilizando un estéreo microscopio con un aumento de 10X. Los datos reco-lectados se analizaron a través de las pruebas de Kruskal-Wallis (p≤0.05) para comparar todos los grupos y la prueba U de Mann-Whitney (p≤0.05) para comparaciones individuales. Resultados: Independientemente del tratamiento realizado todos los grupos presentaron un desgaste del esmalte. El mayor desgaste se registró para el grupo tratado con fresa de halo amarillo (122,66 ± 22,64µm) y el menor desgaste para el grupo de arenado (11,5 ± 2,36µm). Se presentó diferencia estadísticamente significativa entre todos los grupos. Conclusiones: Bajo las limitaciones del presente estudio se puede concluir: La mayor microabrasión en esmalte se produjo con fresas de grano extrafino (halo amarillo) y el menor desgaste se produjo con arenado.

Introduction: Microabrasion is described as a procedure performed on tooth enamel in which the use of an acidic agent and an abrasive agent can correct surface chromatic alterations. Some studies show how the parameters of time, number of applications and the pressure exerted influence the amount of enamel removed.Objective: To establish the thickness of tooth enamel removed according to the abrasive capacity of 9 mechanical chemical treatments, using stereomicroscopy. Materials and methods: With the endorsement of the ethics committee of the School of Dentistry of the National University of Colombia, 90 third molars were collected under informed consent and kept stored under the parameters of ISO 11405. Acrylic blocks were fixed the lingual halves of the dental crowns, creating on them flat surfaces by means of series of sandpaper with irrigation and taking impressions with silicone of addition.They were distributed randomly in 9 groups (n 10). Each group was treated for a period of 30 seconds: G1: Opalustre® (Ultradent), G2: Pumice and 37% phosphoric acid (Ultra-Etch®, Ultradent), G3: Pumice, glycerin and phosphoric acid 37 % (Ultra-Etch®, Ultradent), G4: Yellow halo straw-berries (Komet), G5: White halo strawberries (Komet), G6: Sof-Lex® discs (3M), yellow color, G7: Sof-Lex discs ® (3M), yellow and light yellow, G8: Sandblasted, and G9: Perfect Margin ultrasonic tips (Acteon). The wear thickness created was measured using a stereo microscope with an increase of 10X. The collected data were analyzed through the Kruskal-Wallis tests (p≤0.05) to compare all groups and the Mann-Whitney U test (p≤0.05) for individual comparisons. Results: Regard-less of the treatment performed, all groups presented enamel wear. The highest wear was recorded for the group treated with yellow halo strawberry (122.66 ± 22.64µm) and the lowest wear for the sandblasting group (11.5 ± 2.36µm). There was a statistically significant difference between all groups. Conclusions: Under the limitations of the present study, it can be concluded: The greatest microabrasion in enamel was produced with strawberries of extra-fine grain (yellow halo) and the least wear occurred with sandblasting.

Introdução: A microabrasão do esmalte dental é descrita como um procedimento realizado no esmalte dentário, no qual o uso de um agente ácido e um abrasivo pode corrigir alterações cromáticas na superfície. Alguns estudos mos-tram como os parâmetros de tempo, número de aplicações e pressão exercida influenciam na quantidade do esmalte removido. Objetivo: Estabelecer a espessura do esmalte dentário removido de acordo com a capacidade abrasiva de 9 tratamentos químicos ou mecânicos, utilizando estereomicroscopia. Materiais e métodos: Com o aval do comitê de ética da Faculdade de Odontologia da Universidade Nacional da Colômbia, 90 terceiros molares hígidos foram coletados sob consentimento informado e mantidos armazenados sob os parâmetros da norma ISO 11405. Em blocos de acrílico foram fixadas as metades linguais das coroas dentárias, criando sobre elas superfícies planas por meio de séries de lixa mais irrigação e toma de impressões com silicone de adição. Eles foram distribuídos aleatoriamente em 9 grupos (n= 10). Cada grupo foi tratado por um período de 30 segundos: G1: Opalustre® (Ultradent), G2: Pedra-pomes e ácido fosfórico a 37% (Ultra-Etch®, Ultradent), G3: Pedra-pomes, glicerina e ácido fosfórico 37 % (Ultra-Etch®, Ultradent), G4: brocas diaman-tadas halo amarelo (Komet), G5: brocas diamantadas halo branco (Komet), G6: discos Sof-Lex® (3M), cor amarelo, G7: discos Sof-Lex ® (3M), amarelo e amarelo claro, G8: jateamento e G9: pontas ultra-sônicas Perfect Margin® (Acteon). A espessura de desgaste criada foi medida usando um microscópio estéreo com um aumento de 10X. Os dados coletados foram analisados pelos testes de Kruskal-Wallis (p≤0,05) para comparar todos os grupos e pelo teste U de Mann-Whit-ney (p≤0,05) para comparações individuais. Resultados: Independentemente do tratamento realizado, todos os grupos apresentaram desgaste do esmalte. O maior desgaste foi registrado para o grupo tratado com broca diamantada com halo amarelo (122,66 ± 22,64 µm) e o menor desgaste para o grupo de jateamento (11,5 ± 2,36 µm). Houve diferença estatisticamente significante entre todos os grupos. Conclusões: Sob as limitações do presente estudo, pode-se concluir que a maior microabrasão no esmalte foi produzida com brocas de grão extra-fino (halo amarelo) e o menor desgaste ocorreu com o jateamento.

Avaliação da resistência de união de uma cerâmica de óxido de zircônia submetida a tratamentos de superfície por abrasão / Evaluation of the bond strength of a ceramics of zirconia oxide subjected to surface treatments by abrasion

Resumo Introdução A cimentação adesiva, com cerâmicas puras, é um passo relevante no estabelecimento da longevidade de trabalhos protéticos, sendo estes os melhores materiais utilizados para a reposição de dentes perdidos, de forma a reabilitar o sorriso. O sistema cerâmico de zircônia não se beneficia do tratamento com ácidos e necessita de diferentes métodos para tratar sua superfície, visando à efetividade na união adesiva. Objetivo Avaliar os resultados de diferentes técnicas de jateamento e aplicação de agente de união desenvolvidas para metais e cerâmica de zircônia (Ceramill ZI®), por meio de ensaio de tração, em dois diferentes tratamentos de superfície. Material e método Foram preparadas 20 amostras de Ceramill Zi® (n = 20), em forma de cilindro, e unidas entre si por meio do cimento resinoso (Multilink®), formando 10 espécimes (n = 10). Formaram-se sete grupos experimentais com os mesmos 10 espécimes e estes receberam dois tratamentos de superfície diferentes: abrasão e aplicação de agentes silânicos de união. Resultado A análise estatística mostrou diferenças significativas na resistência à fratura dos espécimes silicatizados com Rocatec®. Os valores de resistência de união à tração, mensurados em MPa, dos grupos 1 a 7, foram, respectivamente: 2,27; 4,48; 8,06; 8,32; 9,15; 10,56 e 10,70. As médias entre os grupos se apresentam estatisticamente significantes, exceto entre os grupos 3 e 4 e entre 6 e 7. Conclusão Os resultados mostraram que o tratamento da superfície cerâmica baseado no método de silicatização promoveu melhor união nos ensaios com Ceramill ZI® e cimentados com Multilink®.

Abstract Introduction Adhesive cementation, with pure ceramics, is a relevant step in establishing the longevity of prosthetic works. Being these, the best materials used for the replacement of lost teeth, in order to rehabilitate the smile. The ceramic zirconia system does not benefit from the treatment and planning needs for its surface, effectively in adhesive therapy. Objective Evaluate the results of different blasting techniques and application of bonding agent for metals and ceramics (Ceramill ZI®) by means of a tensile test in two different surface treatments. Material and method Twenty samples of Ceramill Zi® (n = 20), cylindrical and joined with resin cooling (Multilink®), were prepared, forming 10 specimens (n ​​= 10). The first 10 ingredients were formed by 7 experimental groups and they received 2 surface problems: abrasion and application of silane bonding agents. Result The research resulted in fracture resistance of Rocatec® silica specimens. The values ​​of tensile strength, measured in MPa, of groups 1 to 7, were: 2.27; 4.48; 8.06; 8.32; 9.15; 10.56 and 10.70. We observe how to enter the groups are statistically significant, except between groups 3 and 4 and between 6 and 7. Conclusion The results of the ceramic surface treatment were based on no silicate method, promoting the union of results with Ceramill ZI® and cemented with Multilink®.

Dentin pretreatment and adhesive temperature as affecting factors on bond strength of a universal adhesive system

Abstract Objectives: To evaluate the effects of dentin pretreatment and temperature on the bond strength of a universal adhesive system to dentin. Material and Methods: Ninety-six extracted non-carious human third molars were randomly divided into 12 groups (n=8) according to Scotchbond Universal Adhesive (SbU) applied in self-etch (SE) and etch-and-rinse (ER) mode, adhesive temperature (20°C or 37°C) and sodium bicarbonate or aluminum oxide air abrasion. After composite build up, bonded sticks with cross-sectional area of 1 mm2 were obtained to evaluate the microtensile bond strength (μTBS). The specimens were tested at a crosshead speed of 0.5 mm/min on a testing machine until failure. Fractured specimens were analyzed under stereomicroscope to determine the failure patterns in adhesive, cohesive (dentin or resin) and mixed fractures. The microtensile bond strength data was analyzed using two-way ANOVA and Tukey's test (α=5%). Results: Interaction between treatment and temperature was statistically significant for SbU applied in self-etch technique. Both dentin treatments showed higher bond strength for ER mode, regardless of adhesive temperature. When compared to control group, sodium bicarbonate increased bond strength of SbU in SE technique. Adhesive temperature did not significantly affect the μTBS of tested groups. Predominantly, adhesive failure was observed for all groups. Conclusions: Dentin surface treatment with sodium bicarbonate air abrasion improves bond strength of SbU, irrespective of adhesive application mode, which makes this approach an alternative to increase adhesive performance of Scotchbond Universal Adhesive to dentin.

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.

Effects of air-abrasion pressure on the resin bond strength to zirconia: a combined cyclic loading and thermocycling aging study

OBJECTIVES: To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide (Al₂O₃) particles at different pressures. MATERIALS AND METHODS: Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and χ² tests (α = 0.05). RESULTS: The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. CONCLUSIONS: CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.

Análise comparativa da resistência de união de um cimento convencional e um cimento autoadesivo após diferentes tratamentos na superfície de pinos de fibra de vidro / Bond strength comparative analysis of a conventional cement with a self-adhesive cement after different treatments on the fiberglass post surface

Introdução: Os pinos de fibra de vidro são uma alternativa aos núcleos metálicos e apresentam vantagens, tais como: estética, módulo de elasticidade semelhante à dentina e cimentação imediata após o término do tratamento endodôntico. Ainda, apresentam a capacidade de aderir ao cimento resinoso e este, à dentina, por meio de técnicas adesivas. Objetivo: Comparar a adesão de um cimento resinoso convencional e um autoadesivo a pinos de fibra de vidro, e os efeitos de diferentes tratamentos de superfície na resistência adesiva dos pinos. Material e método: Trinta pinos foram divididos em três grupos: Controle: sem tratamento na superfície; Jateamento: jateamento com óxido de alumínio por 30 segundos, e Peróxido: imersão em peróxido de hidrogênio 24% por um minuto. Em seguida, corpos de prova foram obtidos a partir de cilindros de cimento resinoso contendo o pino de fibra posicionado no centro de seu longo eixo. Em cada grupo, cinco pinos foram associados ao adesivo Âmbar + cimento convencional AllCem Core e os outros cinco pinos, ao cimento autoadesivo RelyX U200. O conjunto pino/cimento foi segmentado e avaliado em relação à resistência de união (RU) por push-out. Os dados foram analisados estatisticamente pelos testes de ANOVA e Tukey (p< 0,05). Resultado: Os cimentos avaliados exibiram valores de RU semelhantes. Em relação aos tratamentos de superfície, os maiores valores de RU foram encontrados no grupo Jateamento. Conclusão: O cimento convencional, AllCem Core, e o cimento autoadesivo, RelyX U200, mostraram valores de resistência de união semelhantes. Ainda, o jateamento com óxido de alumínio favoreceu a adesão dos pinos aos cimentos.

Introduction: The fiberglass posts are an alternative to the metal cast, presenting some advantages, such as aesthetics, tensile modulus similar to dentin and can be placed in a single session, immediately after the endodontic treatment. It also has the ability to adhere to the resin cement and the last to dentin by means of bonding techniques. Objective: To compare the adhesion of a conventional resin cement with a self-adhesive to fiberglass posts, and the effects of different surface treatments on adhesion of posts. Material and method: Thirty fiber posts were divided into 3 groups: control: untreated surface; Blasting: blasting with aluminum oxide for 30 seconds and peroxide: immersion in 24% hydrogen peroxide for 1 minute. Then, the samples were obtained from resin cement cylinders containing the fiber post positioned in the center of its long axis. In each group 5 posts were associated with the adhesive Ambar+conventional cement Allcem Core and the other 5 posts with the self-adhesive cement RelyX U200. The post/cement sample was segment in discs and evaluated for bond strength (BS) by push-out test. Data were analyzed statistically by ANOVA and Tukey tests (p< 0.05). Result: The cements evaluated exhibited similar BS values. Regarding surface treatments, the highest BS values were found in blasting group. Conclusion: Conventional cement, Allcem Core, and self-adhesive, RelyX U200, showed similar bond strength values. Also, blasting with aluminum oxide favored the adhesion of posts to cements.

Bond strenght of zirconia submitted to different surface treatments

To evaluate the shear bond strength of a recent adhesive system used in the cementation of zirconia.Material and Methods:Overall, 72 zirconia specimens (Zirconzhan) were divided and randomized into 3 groups according to the type of surface treatment: G1 no treatment + adhesive system; G2 blasted with aluminum oxide + adhesive system and G3 tribochemical treatment (Rocatec Plus) + adhesive system. Half of each group (n = 12) had bond strength evaluated on two occasions: 24 hours after cementation, kept stored in distilled water at 37 ° C without thermal cycling, and after thermal cycling (5000 cycles, 5°C-55°C). Data were analyzed by ANOVA with Tukey's post-test (α≤0.05).Results:At first moment, G1 and G3 showed higher bond strength (8.64 ± 3.43 MPa and 6.55 ± 2.27 MPa) compared to G2, with no statistically significant difference between them. After thermal cycling, G3 showed higher bond strength (7.70 ± 1.82 MPa).Conclusion:Initially, only the adhesive system promoted higher bond strength, but after thermal cycling,bond strength decreased. The best treatment to promote high bond strength to zirconia is to associate tribochemical treatment with the adhesive system; most failures observed after thermal cycling were mixed and cohesive, showing a mechanical imbrication of the adhesive system, suggesting that there is no chemical bond; and the surface of the group with greater bond strength after thermal cycling showed more surface irregularities compared to the other groups...

Influence of sandblasting distance on enamel and ceramic structure bond strength / Influência do jateamento na estrutura cerâmica e esmalte, alterando a distância na resistência de união

Objetive: The purpose of this study was to evaluate the influence of sandblasting distance on ceramic and enamelbond strength. Material & Methods: Sixtythird molars were selected, enamel surfaces were ground flat with wet 600 - 2000 grit aluminum oxide abrasive papers and polished with three, one, and one-fourth micrometer-grit diamond pastes. On hundred and twentylithium disilicate-based core ceramic discs (2 mm diameter; 1 mm thickness) were also obtained and further divided into 7 groups [Group C, no sandblasting, Group SB-E(5-10) enamel sandblasting - 5 and 10 mm of distance, Group SBC(5-10) ceramic sandblasting 5 mm and 10 mm of distance, Group SB-EC(5-10) enamel and ceramic sandblasting 5 mm and 10 mm of distance]. After treatments,shear and Atomic Force Microscopy (AFM) tests were performed.Data were analyzed by Statistic Tests of normality, one-way ANOVA and Tukey post-test (α: 0.05). Results: Group C presented the highestbond strength values(59.2 ±12.5), while group SB-E 5 mm showed the lowest values (21.7 ± 08.8) (p < 0.005). Conclusion: The use of sandblasting treatment of enamel surface at 5mm distance decreases the bonding strength to shear.

Objetivo: o objetivo do estudo foi avaliar influência do jateamento na estrutura cerâmica e esmalte sob resistência de união, mudando a distância. Materiais e Métodos: 60 terceiros molares, foram selecionados, superfícies de esmalte foram planificadas com lixa com grão 600 - 2000 lixas e polido com pastas de diamante de um grão -micrômetro. Obtidos 120 discos cerâmica em dissilicato de lítio de (2 mm de diâmetro e 1 mm de espessura), dividido em sete grupos [Grupo C, não jateamento, Grupo SB-E (5-10) esmalte jateamento 5 e 10 mm, Grupo SB -C (5-10) de jacto de areia cerâmica 5 mm e 10 mm, Grupo SB-CE (5-10) e esmalte cerâmico areação 5 milímetros e 10 mm], depois foi realizado o microcisalhamento e a microscopia de forca atômica (AFM), estatística como Teste de Normalidade , após análise de variância one-way e teste de Tukey (α: 0,05). Resultados: A força do grupo C apresentou maiores valores de resistência de união (59,2 ± 12,5), o grupo SB-E 5 mm (21,7 ± 08,8) (p < 0,005), o grupo SB-E10 (53,6 ± 14,3). Conclusão: o uso de jateamento tratamento da superfície do esmalte de 5 mm, de 20 s diminui a força de ligação de microcisalhamento.

Efeito da partícula e do momento de jateamento na caracterização superficial da zircônia e na resistência de união com cimento resinoso / Effect of particle and the air abrasion moment on surface characterization of zirconia and bond strength with resin cement

Apesar das restaurações em cerâmicas Y-TZP (Yttria tetragonal zirconia polycrystal) estarem sendo cada vez mais utilizadas na prática clínica devido às suas excelentes propriedades, tratamentos de superfície ainda são necessários para a melhoria de sua adesão com cimentos resinosos. Este estudo avaliou a influência da partícula e do momento do jateamento na caracterização superficial de uma cerâmica Y-TZP e na sua resistência de união com cimento resinoso. Espécimes de zircônia foram submetidos aos seguintes tratamentos com jateamento: partículas de Al2O3 de 50 µm; partículas de Al2O3 de 120 µm; partículas de Al2O3 de 30 µm modificadas por sílica (Rocatec Soft); e partículas de Al2O3 de 110 µm modificadas por sílica (Rocatec Plus). O jateamento foi realizado em três momentos diferentes: após a sinterização da zircônia (PÓS) (grupo controle); antes da sinterização da zircônia (PRÉ); e antes/após a sinterização (PP). A caracterização da superfície da zircônia incluindo rugosidade superficial (n=10), molhamento (n=10), microscopia eletrônica de varredura (n=2) e composição elementar (n=2) foi realizada. O teste de resistência de união ao cisalhamento (RC) (n=11) foi conduzido após a termociclagem dos espécimes (10000 ciclos - 5°C e 55°C). O modo de fratura foi analisado através de um estereomicroscópio (x 20). Rugosidade, molhamento e RC foram analisados através da ANOVA dois fatores e o teste de Tukey (α=,05). Nos grupos PRÉ e PP, a rugosidade aumentou de acordo com o tamanho da partícula. Independentemente da partícula, o grupo PÓS apresentou os menores valores de rugosidade, enquanto os grupos PRÉ e PP não apresentaram diferença significativa entre eles. De uma maneira geral, as partículas de Al2O3 de 120 µm e Rocatec Plus apresentaram os maiores e menores ângulos de contato. Com relação à partícula, os grupos PRÉ e PP exibiram o maior e o menor ângulo de contato o, enquanto o grupo controle (PÓS) apresentou uma posição intermediária. A partícula e o momento do jateamento não promoveram padrões morfológicos uniformes. A presença adicional do elemento Si nos grupos Rocatec Soft e Plus foi a única diferença observada entre esses grupos em relação aos grupos com partículas de Al2O3. No grupo PRÉ, os maiores e menores valores de RC foram obtidos por Al2O3 de120 µm e Rocatec Soft. Nos grupos PP e PÓS, o maior RC foi observado quando o jateamento foi realizado com partículas de Al2O3 modificadas por sílica. Não houve diferença significativa na RC entre os grupos PÓS e PP. Todos os grupos exibiram 100% de falha adesiva. A partícula teve maior influência na rugosidade, quando o jateamento foi realizado antes da sinterização da zircônia, mostrando um maior potencial para a deformação da superfície. Quando o jateamento é realizado após a sinterização (grupos PP e PÓS), as partículas de Al2O3 modificadas por sílica promoveram maior molhamento e valores de RC

Despite Y-TZP (yttria tetragonal zirconia polycrystal) ceramic restorations became widely used in clinical practice due to its excellent properties, surface treatments are required for the improvement of the adhesion with resin cements. This study evaluated the influence of the particle and air abrasion moment on the surface characterization of a Y-TZP ceramic and its bond strength with a resin cement. Zirconia specimens were air-abraded with the following particles: 50 µm Al2O3 particles; 120 µm Al2O3 particles; 30 µm silica-coated Al2O3 particles (Rocatec Soft); and 110 µm silica-coated Al2O3 particles (Rocatec Plus). Air-abrasion was performed in 3 different moments: after zirconia sintering (AS)(control group); before zirconia sintering (BS); before and after zirconia sintering (BAS). The zirconia surface characterization including roughness (n=10), wettability (n=10), morphology (n=2) and elemental composition (n=2) was performed. The SBS test (n=11) was conducted after thermal cycling (10,000 cycles - 5ºC and 55ºC). Failure mode was determined with a stereomicroscope (×20). Roughness, wettability and SBS data were analyzed by two-way ANOVA and Tukey's test (α=.05). For BS and BAS, the roughness increased according to the increase in the particle size. AS showed the lowest roughness, while BS and BAS did not exhibit significant difference each other. In general, Rocatec Plus and 120 µm Al2O3 particles provided the lowest and the highest contact angle. BS and BAS exhibited the highest and the lowest contact angle. The particle as well as the air-abrasion moment did not promote regular morphological patterns. The additional presence of the Si element in the groups abraded with silica-modified Al2O3 particles was the only difference observed between these groups and those abraded with Al2O3 particles. For BS, the highest and the lowest SBS was provided by 120 µm Al2O3 particles and Rocatec Soft. For BAS and AS, the highest SBS was achieved with the silica-modified Al2O3 particles. There was no significant difference in SBS between the AS and BAS groups. All groups exhibited 100% adhesive failures. The particle influenced more the roughness when air-abrasion was performed before sintering, having a greater potential to imprint the zirconia surface. When air-abrasion happens after sintering (BAS and AS), silica-modified Al2O3 particles provided higher wettability and SBS values

Surface treatment of feldspathic porcelain: scanning electron microscopy analysis

PURPOSE: Topographic analysis of treated ceramics provides qualitative information regarding the surface texture affecting the micromechanical retention and locking of resin-ceramics. This study aims to compare the surface microstructure following different surface treatments of feldspathic porcelain. MATERIALS AND METHODS: This in-vitro study was conducted on 72 porcelain discs randomly divided into 12 groups (n=6). In 9 groups, feldspathic surfaces were subjected to sandblasting at 2, 3 or 4 bar pressure for 5, 10 or 15 seconds with 50 microm alumina particles at a 5 mm distance. In group 10, 9.5% hydrofluoric acid (HF) gel was applied for 120 seconds. In group 11, specimens were sandblasted at 3 bar pressure for 10 seconds and then conditioned with HF. In group 12, specimens were first treated with HF and then sandblasted at 3 bar pressure for 10 seconds. All specimens were then evaluated under scanning electron microscopy (SEM) at different magnifications. RESULTS: SEM images of HF treated specimens revealed deep porosities of variable sizes; whereas, the sandblasted surfaces were more homogenous and had sharper peaks. Increasing the pressure and duration of sandblasting increased the surface roughness. SEM images of the two combined techniques showed that in group 11 (sandblasted first), HF caused deeper porosities; whereas in group 12 (treated with HF first) sandblasting caused irregularities with less homogeneity. CONCLUSION: All surface treatments increased the surface area and caused porous surfaces. In groups subjected to HF, the porosities were deeper than those in sandblasted only groups.

Percepção dos responsáveis sobre fatores preditores do medo odontológico infantil e aceitação do uso da abrasão a ar / Caregivers'perceptions of predictors of children's dental fear and acceptance of the use of air abrasion

O objetivo deste artigo é avaliar a percepção de responsáveis sobre fatores preditores do medo odontológico e aceitação do uso de uma nova tecnologia para remoção do tecido cariado em suas crianças. Entrevista a partir de um questionário semiestruturado com 105 responsáveis por crianças, de 2 a 12 anos, atendidas na Clínica de Odontopediatria, a respeito do nível de medo/apreensão, conhecimento e importância de novos estudos e autorização para utilização de novas tecnologias. Os dados foram analisados descritivamente e utilizando o teste Exato de Fisher (p<0,05). Embora os responsáveis tenham poucas informações sobre os métodos alternativos de remoção de cárie, eles são receptivos ao uso dos mesmos em seus filhos.

The purpose this article is to evaluate the caregivers'perception of predictors of dental fear and acceptance of use a new technology for removal of caries in their children. Interview using a semi-structured questionnaire with 105 caregivers for children 2 to 12 years attending at Clinic of Pediatric Dentistry. The data were about dental fear/ apprehension; knowledge and importance of new studies and permission to use new technologies. Data were analyzed descriptive and using the Fisher’s Exact test (p <0.05). A lthough t he c aregivers have little information about alternative methods of caries removal, they are receptive to use them in their children.

The effect of alumina and aluminium nitride coating by reactive magnetron sputtering on the resin bond strength to zirconia core

PURPOSE: Although several surface treatments have been recently investigated both under in vitro and in vivo conditions, controversy still exists regarding the selection of the most appropriate zirconia surface pre-treatment. The purpose of this study was to evaluate the effect of alumina (Al) and aluminium nitride (AlN) coating on the shear bond strength of adhesive resin cement to zirconia core. MATERIALS AND METHODS: Fifty zirconia core discs were divided into 5 groups; air particle abrasion with 50 microm aluminum oxide particles (Al2O3), polishing + Al coating, polishing + AlN coating, air particle abrasion with 50 microm Al2O3 + Al coating and air particle abrasion with 50 microm Al2O3 + AlN coating. Composite resin discs were cemented to each of specimens. Shear bond strength (MPa) was measured using a universal testing machine. The effects of the surface preparations on each specimen were examined with scanning electron microscope (SEM). Data were statistically analyzed by one-way ANOVA (alpha=.05). RESULTS: The highest bond strengths were obtained by air abrasion with 50 microm Al2O3, the lowest bond strengths were obtained in polishing + Al coating group (P<.05). CONCLUSION: Al and AlN coatings using the reactive magnetron sputtering technique were found to be ineffective to increase the bond strength of adhesive resin cement to zirconia core.