Can different etching protocols change the properties of a hybrid ceramic?

The aim of this study was to evaluate the effects of different concentrations of hydrofluoric acid (HF) and etching times on the flexural strength, roughness, wettability, and type of failure of a hybrid ceramic (VITA ENAMIC). Blocks of the ceramic material were made according to the norms of International Organization for Standardization standard 6872:2015 and randomly divided into 7 groups (n = 13): control (no treatment); surface etching with 5% HF for 30 (HF5-30), 60 (HF5-60), or 90 (HF5-90) seconds; and surface etching with 10% HF for 30 (HF10-30), 60 (HF10-60), or 90 (HF10-90) seconds. The adhesive surface of 10 specimens in each group was cemented with dual-curing resin cement. The specimens were submitted to biaxial flexural tests and fractographic analysis. Surface analyses were carried out using 3 noncemented specimens from each group. The surface roughness was evaluated through optical profilometry and the surface wettability through goniometry (contact angle). The values obtained were analyzed by a Dunnett test followed by 2-way analysis of variance and Tukey test (α = 5%). The flexural test results indicated a statistically significant reduction in the resistance of the ceramic when conditioned with 10% acid (P < 0.01). Etching with HF, at any concentration used for any applied time, significantly modified the ceramic roughness of the experimental groups (P < 0.01). The wettability was also significantly altered in the HF5-90 group and in all HF10 groups (P < 0.01). The higher the concentration of the acid, the lower the wettability of the ceramic (P < 0.01). Based on these results, a 5% HF concentration is best indicated for the surface treatment of VITA ENAMIC.

Bond strength between a polymer-infiltrated ceramic network and a composite for repair: effect of several ceramic surface treatments.

The effects of several ceramic surface treatments on bond strength of a polymer-infiltrated ceramic network and resin composite as repair material were evaluated. CAD-CAM blocks of a polymer-infiltrated ceramic network (Vita Enamic) were sliced and subjected to aging process, followed by embedding in acrylic resin. The bonding/repair area was treated as follows (n = 30): C- without treatment; UA- universal adhesive application; FM- 10% hydrofluoric acid and silane application; OM-airborne-particle abrasion with aluminum oxide and silane application; RP- tribochemical silica coating; and CA- surface grinding and application of universal adhesive. Composite resin cylinders were made on the treated surface. Specimens from each group were assigned randomly to two subgroups (n = 15) considering storage condition: Baseline (shear tests after 48 hours) or Storage (tests after 6 months under distilled water). The treated surfaces were analyzed by goniometry, roughness, and SEM. Two-way ANOVA and 1-way ANOVA were applied to analyze the bond data and roughness / contact angle data, respectively, followed by Tukey's test (α = 5%). Surface treatments and storage conditions affected bond strengths (p < 0.01). Surface grinding (CA) followed by universal adhesive promoted the highest value of bond strength (14.5 ± 4.8 MPa for baseline, 8.5 ± 3.4 MPa for storage) and the roughest ceramic surface. Grinding with silicon carbide paper (simulating diamond bur) followed by the application of a universal adhesive system is the best option for repairing fractures of the polymer-infiltrated ceramic network.

Bond strength between a polymer-infiltrated ceramic network and a composite for repair: effect of several ceramic surface treatments

Abstract: The effects of several ceramic surface treatments on bond strength of a polymer-infiltrated ceramic network and resin composite as repair material were evaluated. CAD-CAM blocks of a polymer-infiltrated ceramic network (Vita Enamic) were sliced and subjected to aging process, followed by embedding in acrylic resin. The bonding/repair area was treated as follows (n = 30): C- without treatment; UA- universal adhesive application; FM- 10% hydrofluoric acid and silane application; OM-airborne-particle abrasion with aluminum oxide and silane application; RP- tribochemical silica coating; and CA- surface grinding and application of universal adhesive. Composite resin cylinders were made on the treated surface. Specimens from each group were assigned randomly to two subgroups (n = 15) considering storage condition: Baseline (shear tests after 48 hours) or Storage (tests after 6 months under distilled water). The treated surfaces were analyzed by goniometry, roughness, and SEM. Two-way ANOVA and 1-way ANOVA were applied to analyze the bond data and roughness / contact angle data, respectively, followed by Tukey's test (α = 5%). Surface treatments and storage conditions affected bond strengths (p < 0.01). Surface grinding (CA) followed by universal adhesive promoted the highest value of bond strength (14.5 ± 4.8 MPa for baseline, 8.5 ± 3.4 MPa for storage) and the roughest ceramic surface. Grinding with silicon carbide paper (simulating diamond bur) followed by the application of a universal adhesive system is the best option for repairing fractures of the polymer-infiltrated ceramic network.

Caracterização microestrutural de um esmalte dentário submetido à radiação ionizante e ensaio de desgaste antagonizados por uma cerâmica híbrida / Microstructural characterization of a gamma irradiated dental enamel and wear performance antagonized by a hybrid ceramic

A radioterapia de cabeça e pescoço pode alterar e causar danos à estrutura dentária. Anteriormente a radioterapia, estes pacientes devem passar por consultas e tratamento odontológico orais, sugerindo a cerâmica híbrida como escolha para reabilitações orais, uma vez que esta cerâmica apresenta a característica de menor desgaste do dente. O presente estudo objetivou avaliar o efeito de diferentes doses de radiação ionizante sobre: o comportamento mecânico e estrutural da cerâmica híbrida; as propriedades mecânicas e químicas do esmalte dentário; o desempenho do esmalte dentário irradiado e dois materiais antagonistas distintos (Enamic e Esteatita). Para isto, discos de Enamic e os fragmentos dentais foram submetidos às doses diárias de 2 Gy; totalizando as doses: 0, 20, 40 e 70 Gy (esmalte e Enamic), e, 50 Gy e 60 Gy (esmalte). Após a radiação, as cerâmicas foram analisadas mecanicamente pelos testes de: dureza e flexão biaxial, e, quimicamente pelo FT-IR. Enquanto, os fragmentos de dentes (n = 60) foram observados: a degradação estrutural por FT-IR e DR-X (n=5), a nanodureza e módulo elástico (n = 10), teste de riscamento (n = 3) e desgaste antagonizados por Enamic e Esteatita (n = 10). Os dados foram submetidos aos testes ANOVA (1 e 2 fatores) e Tukey. Mediante os resultados observados, conclui-se que a radiação ionizante não alterou as propriedades da cerâmica híbrida e as propriedades cristalinas do esmalte dentário, porém, alterou a dureza, o módulo elástico, a resistência ao riscamento, a composição química (degradação do colágeno) e desgaste do esmalte dentário(AU)

The head and neck radiotherapy treatment can change and damage the dental structure. Before the radiotherapy treatment, the patients should have a dental consultation and to submit to dentistry treatments, suggesting the hybrid ceramics material are suggested as the choice to oral rehabilitations, for this material shows the characteristic of less damage of the tooth. This study aimed to evaluate the effects of different doses of gamma irradiation on: mechanical and structural behavior of hybrid ceramics; mechanical and chemical properties of dental enamel; the wear performance of irradiated dental enamel and two distinct antagonist materials (Enamic and Steatite). For that, Enamic discs (ISO 6872) and dental fragments were submitted to daily irradiation doses of 2 Gy; about the doses adding up to: 0, 20, 40 and 70 Gy (enamel and Enamic), and, 50 Gy and 60 Gy (enamel only). Then Following that procedure, ceramics were analyzed for: hardness (n = 4), biaxial flexural (n = 10) and chemically by FT-IR (n = 2). While In the meantime, 60 fragments of third molars were observed about: structural degradation by FT-IR and DR-X (n = 5), nano hardness and elastic modulus (n = 10), scratch test (n = 3), chewing simulator test antagonized by: Enamic and steatite (n = 10). The data were submitted to ANOVA- 1Way, and ANOVA-Two Way and Tukey's Test. It is This study concluded that: gamma irradiation did not affect the properties of the hybrid ceramics and the crystalline properties of the dental enamel; however, composition and mechanical properties were affected, such as: hardness, elastic modulus, scratch resistance, chemical composition (collagen degradation) and tooth enamel wear(AU)