An engineering perspective of ceramics applied in dental reconstructions

Abstract The demands for dental materials continue to grow, driven by the desire to reach a better performance than currently achieved by the available materials. In the dental restorative ceramic field, the structures evolved from the metal-ceramic systems to highly translucent multilayered zirconia, aiming not only for tailored mechanical properties but also for the aesthetics to mimic natural teeth. Ceramics are widely used in prosthetic dentistry due to their attractive clinical properties, including high strength, biocompatibility, chemical stability, and a good combination of optical properties. Metal-ceramics type has always been the golden standard of dental reconstruction. However, this system lacks aesthetic aspects. For this reason, efforts are made to develop materials that met both the mechanical features necessary for the safe performance of the restoration as well as the aesthetic aspects, aiming for a beautiful smile. In this field, glass and high-strength core ceramics have been highly investigated for applications in dental restoration due to their excellent combination of mechanical properties and translucency. However, since these are recent materials when compared with the metal-ceramic system, many studies are still required to guarantee the quality and longevity of these systems. Therefore, a background on available dental materials properties is a starting point to provoke a discussion on the development of potential alternatives to rehabilitate lost hard and soft tissue structures with ceramic-based tooth and implant-supported reconstructions. This review aims to bring the most recent materials research of the two major categories of ceramic restorations: ceramic-metal system and all-ceramic restorations. The practical aspects are herein presented regarding the evolution and development of materials, technologies applications, strength, color, and aesthetics. A trend was observed to use high-strength core ceramics type due to their ability to be manufactured by CAD/CAM technology. In addition, the impacts of COVID-19 on the market of dental restorative ceramics are presented.

Fit of metal-ceramic crowns: effect of coping fabrication method and veneering ceramic application

Aim: To evaluate the influence of cobalt-chromium (Co-Cr) coping fabrication methods and ceramic application on the marginal and internal fit of metal-ceramic crowns. Methods: Co-Cr copings for metal-ceramic crowns were prepared by lost wax casting or CAD-CAM machining of sintered blocks. The fit was analyzed using the silicone replica technique at four assessment points: marginal gap (MG), axial wall (AW), axio-occlusal (AO) angle, and central occlusal (CO) wall. After the initial analysis, the copings were ceramic-veneered with the layering technique, and the fit was again determined. Data were statistically analyzed by paired and unpaired Student's-t test (α=0.05). Results: Marginal and internal fit before ceramic application according to the coping manufacturing method showed significant differences only at CO (p < 0.001), with milled copings (137.98±16.71 µm) showing higher gap values than cast copings (112.86±8.57 µm). For cast copings, there were significant differences at MG (before 109.13±8.79 µm; after 102.78±7.18 µm) and CO (before 112.86±8.57 µm; after 104.07±10.63 µm) when comparing the fit before and after ceramic firing. For milled copings, there was significant difference only at AO (before 116.39±9.64 µm; after 108.54±9.26 µm). Conclusion: This study demonstrated that the coping fabrication method influenced the internal fit. Ceramic firing maintained or improved the fit of the metal-ceramic crowns. The marginal discrepancy of all restorations, before and after ceramic firing, can be considered clinically acceptable

Metal Alloys in Dentistry: An Outdated Material or Required for Oral Rehabilitation?

ABSTRACT: The present study aims to describe through a literature review, the main types of noble and non-noble alloys in dentistry looking to identify the adhesion mechanisms, compositions and mechanical properties, and its applicability as a rehabilitation resource nowadays. A bibliographic search was conducted in the main health databases PUBMED (www.pubmed.gov) and Scholar Google (www.scholar.google.com.br), in which studies published from 1971 to 2021 were collected. Laboratory studies, case reports, systematic and literature reviews, which were developed in living individuals. Articles that did not deal with metal alloys and its use in dentistry were excluded. Through the review, it was possible to ver ify that all works presented the metal alloys and their main properties, indicating that they are divided into three main types: hi gh noble alloys, noble alloys and base metal alloys differing in their levels of constituent noble metals. Several alloys and meta ls are available for the dental market each presenting advantages and disadvantages, mainly based on its specific composition.Continuous research and development are resulting in the production of new technologies and products, giving dental surgeons even more options in the design and manufacture of restorations using metal alloys and understanding that these resources will still be viable alternatives in oral rehabilitations. However, further studies on metal alloys are needed to better understand this subject.

RESUMEN: El presente trabajo tuvo como objetivo describir a través de una revisión de la literatura, los principales tipos de aleaciones nobles y no nobles utilizados en odontología buscando identificar los mecanismos de adhesión, composiciones y propiedades mecánicas, así como reflejar su aplicabilidad como recurso rehabilitador en la actualidad. Realizamos una búsqueda bibliográfica em las principales bases de datos de salud PUBMED (www.pubmed.gov) y Scholar Google (www.scholar.google.com.br), en la que se recopilaron estudios publicados desde 1971 hasta 2021. Estudios de laboratorio, informes de casos, revisiones sistemáticas y bibliográficas, que se desarrollaron en individuos vivos. Sin embargo, se excluyeron los artículos que no trataban sobre aleaciones metálicas y su uso en odontología. Se pudo observar que todos los trabajos presentaban las aleaciones metálicas y sus principales propiedades indicando que se estas dividen en tres tipos principales: aleaciones altamente nobles, aleaciones nobles y aleaciones de metales base que difierenen sus niveles de metales nobles constituyentes. Hay varias aleaciones y metales disponibles para el mercado dental, cada uno presenta ventajas y desventajas, principalmente en función de su composición específica. La investigación y el desarrollo continuo están dando como resultado la producción de nuevas tecnologías y productos, brindando a los cirujanos dentistas aún más opciones en el diseño y fabricación de las restauraciones, utilizando aleaciones metálicas y, permite concluir que estos recursos seguirán siendo alternativas viables en los tratamientos de rehabilitación. Sin embargo, se necesitan más estudios sobre el tema abordado en el trabajo, para una comprensión más profunda del tema.

One Year Clinical Evaluation of Milled BioHPP Polyetheretherketone (PEEK)-Based versus Metal Ceramic Single Crowns (Randomized Controlled Clinical Trial) / Avaliação Clínica de um Ano de Coroas Fresadas à Base de Biohpp Polieteretercetona (PEEK) Versus Coroas Metalocerâmicas Unitárias (Ensaio Clínico Controlado Randomizado)

Objective: To evaluate the clinical behavior of milled BioHPP PEEK copings veneered with Visio.lign composite resin in comparison with metal copings veneered with feldspathic porcelain as single posterior crowns. Material and Methods: Twenty Four full coverage posterior crowns were fabricated for endodontically treated molars divided into 2 groups according to the material used. Twelve milled BioHPP PEEK-based crowns (Group 1) and Twelve Porcelain Fused to Metal (PFM) crowns (Group 2). The preparations were standardized with an equi-gingival, deep chamfer finish line for all teeth. BioHPP PEEK and metal copings were fabricated by CAD/CAM technology and lost wax technique respectively. These coping were veneered according to manufactures instructions either by special composite resin or low fusing glass ceramic respectively. The restorations were cemented then clinical evaluation of these crowns was assessed regarding mechanical failure, marginal integrity and patient satisfaction every two months for one year. Results: Although two PEEK crowns were fractured, both PEEK and PFM crowns showed similar fracture (mechanical failure) and marginal integrity without significant difference (p > 0.05). BioHPP PEEK-based crowns showed statistically significantly lower patient satisfaction than PFM crowns after six months (p-value = 0.013, Effect size = 1.157) but all the patients were generally satisfied. Conclusion: BioHPP PEEK-based crowns showed clinically similar and accepted mechanical behavior and marginal integrity but less patient's satisfaction than PFM crowns after six months. So BioHPP PEEK-based crowns may be used as an alternative tooth-colored metal-free fixed restoration for one year (AU)

Objetivo: Avaliar o comportamento clínico de copings fresados de BioHPP PEEK com cobertura de resina composta Visio.lign em comparação com copings metálicos cobertos com cerâmica feldspática em coroas unitárias posteriores. Material e Métodos: Vinte e quatro coroas totais posteriores de foram confeccionadas para molares tratados endodonticamente e divididos em 2 grupos de acordo com o material utilizado. Doze coroas fresadas à base de BioHPP PEEK (Grupo 1) e doze coroas de porcelana fundida ao metal (PFM) (Grupo 2). Os preparos foram padronizados para todos os dentes com término de chanfro largo ao nível gengival. BioHPP PEEK e os copings metálicos foram fabricados por tecnologia CAD/CAM e técnica da cera perdida, respectivamente. A aplicação da cobertura sobre os copings foi realizada de acordo com as instruções do fabricante, por resina composta especial ou cerâmica vítrea de baixa fusão, respectivamente. As restaurações foram cimentadas e a avaliação clínica dessas coroas foi realizada quanto à falha mecânica, integridade marginal e satisfação do paciente a cada dois meses durante um ano. Resultados: Embora duas coroas de PEEK tenham sido fraturadas, ambas as coroas de PEEK e PFM apresentaram fraturas semelhantes (falha mecânica) e integridade marginal sem diferença significativa (p > 0,05). As coroas à base de BioHPP PEEK mostraram uma satisfação do paciente significativamente menor do que as coroas PFM após seis meses (valor de p = 0,013; tamanho do efeito = 1,157), mas todos os pacientes estavam geralmente satisfeitos. Conclusão: As coroas à base de BioHPP PEEK, em comparação às coroas PFM, mostraram desempenho clínico similar, aceitável comportamento mecânico e integridade marginal, mas menos satisfação do paciente, após seis meses. Portanto, as coroas à base de BioHPP PEEK podem ser utilizadas como uma alternativa de restauração livre de metal semelhante à cor do dente, por um ano. (AU)

Metal-ceramic interface characteristics of Co-Cr alloy fabricated by selective laser melting / 中国组织工程研究

BACKGROUND: Co-Cr ceramic alloys made by selective laser melting technology are widely used in the field of dental restoration, but the influence of selective laser melting technology on the bonding properties of Co-Cr ceramic alloys is still controversial. OBJECTIVE: To explore the metal-ceramic interface characteristics of dental Co-Cr alloy fabricated by selective laser melting. METHODS: Metal-ceramic specimens were prepared by selective laser melting and precision casting, respectively. Metal-ceramic bond strengths, interface characteristics, fracture analysis, microstructures and composition distribution of specimens were obtained with the aid of universal testing machine, metallographic microscope, scanning electron microscope coupled with energy disperse spectrometer. RESULTS AND CONCLUSION: (1) The metal-ceramic bond strengths of precision casting Co-Cr alloy was higher than that of selective laser melting Co-Cr alloy (P < 0.05). (2) Metallographic microscope showed that selective laser melting Co-Cr alloy had fine grains and a more uniform matrix. Precision casting Co-Cr alloy showed typical casting dendritic structure with coarse grains and a large number of island second phase structures. (3) Scanning electron microscopy showed that precision casting Co-Cr alloy had a thicker diffusion layer than the selective laser melting Co-Cr alloy at the metal-ceramic interface. (4) Scanning electron microscopy showed that the metal-ceramic specimens of precision casting Co-Cr alloy tended to cohesive fracture, and the metal-ceramic specimens of selective laser melting Co-Cr alloy tended to adhesive fracture. (5) The results showed that although the bonding strength of selective laser melting Co-Cr alloy was lower than that of precision casting Co-Cr alloy, the bonding strength of selective laser melting Co-Cr alloy could still meet the requirements of standard YY0621.1-2016.

Reabilitação com coroas metal free em dentes anteriores traumatizados e com rizogênese incompleta: relato de caso / Rehabilitation with metal free crowns in traumatized anterior teeth with incomplete rhizogenesis: case report

Objetivo: rizogênese incompleta refere-se a dentes permanentes em que não houve a formação completa do ápice radicular, ocasionando perda da vitalidade pulpar e, consequentemente, incapacidade da bainha epitelial de Hertwig para induzir a formação completa da raiz. Devido ao traumatismo e escurecimento dental, se faz necessário em certos casos a confecção de coroas em porcelana pura para reabilitar a paciente em estética e função. O presente trabalho tem como objetivo demonstrar um caso de reabilitação estética e funcional em dente com rizogênese incompleta, onde se consideraram as perdas estruturais e alteração de cor, para que seja possível estabelecer o tratamento mais adequado. Relato de caso: paciente de 16 anos, gênero feminino, atendida na Clínica de Odontologia de uma instituição privada, insatisfeita com a estética do seu dente devido ao escurecimento do elemento 21, pois quando tinha 5 anos o dente foi traumatizado juntamente com o elemento 11. O plano de tratamento adotado para ambos os elementos foi a confecção de peças protéticas em porcelana e cimentação. Considerações finais: esse caso demonstrou que a confecção de coroas estéticas em porcelana é considerada uma boa conduta na rotina clínica em casos de escurecimento dental, devolvendo estética e função para o paciente.(AU)

Objective: incomplete rhizogenesis refers to permanent teeth with incomplete formation of the root apex, causing loss of pulp vitality and the consequent inability of the Hertwig epithelial sheath to induce complete root formation. Due to dental trauma and darkening, some cases require the production of pure porcelain crowns to rehabilitate the aesthetics and function of patients. The present study aims to show a case of aesthetic and functional rehabilitation in a tooth with incomplete rhizogenesis, in which structural losses and color change were considered to establish the most appropriate treatment. Case report: a 16-year-old female patient treated at the Dental Clinic of a private institution. The patient was not satisfied with the aesthetics of her tooth due to the darkening of element 21, because at 5 years old the tooth was traumatized along with element 11. The treatment used for both elements was the production of prosthetic porcelain crowns and cementation. Final considerations: this case showed that the production of aesthetic porcelain crowns is considered a good conduct in the clinical routine in cases of tooth darkening, returning aesthetics and function to the patient.(AU)

As avaliações longitudinais de cinco anos em próteses cerâmicas totais fixas implantossuportadas são escassas na literatura: uma revisão sistemática / Five-year longitudinal evaluations on implant-supported total fi xed ceramic prostheses are scarce in the literature: a systematic review

Objetivo: a objetivo desta revisão sistemática foi avaliar estudos clínicos e as taxas de sucesso e complicações protéticas das próteses fixas totais cerâmicas implantossuportadas em pacientes totalmente desdentados, após um período de acompanhamento mínimo de 5 anos. Material e métodos: a pesquisa bibliográfica foi realizada usando as bases de dados eletrônicas Medline/PubMed, entre 1980 a 2015, para estudos clínicos em língua inglesa relatando as complicações protéticas e implantares. Os termos de pesquisa que foram utilizados, isoladamente ou em combinação foram implant-supported restoration, prosthodontic complications, technical complications, mechanical complications, dental implants, screw complications, edentulous arch, metal framework fracture, restoration, acrylic veneer fracture, ceramic veneer fracture, biologic complications e edentulous arch. Resultados: dos 181 artigos recuperados, apenas três estudos cumpriram os critérios de inclusão para esta revisão, sendo três estudos prospectivos. As complicações biológicas e técnicas em implantes e próteses foram identificadas e registradas, incluindo: fraturas dos materiais de suporte da estrutura/recobrimento, soltura do parafuso da prótese e/ou parafuso do pilar, fratura do parafuso protético e/ou parafuso do pilar, deficiências estéticas e desgaste do material. Conclusão: dentro dos limites desta revisão sistemática, os estudos sobre materiais cerâmicos com cinco anos ou mais de acompanhamento são escassos ou inexistentes sugerindo cautela na utilização desse tipo de restauração implantossuportada.

Objective: the objective of this systematic review was to access the clinical studies and as success rates and prosthetic complications of total fi xed ceramic prostheses implanted in fully edentulous patients after a minimum follow-up period of 5 years. Material and methods: a literature search was conducted using Medline/PubMed electronic databases from 1980 to 2015 for English-language clinical studies reporting as prosthetic and implant complications. "Technical complications", "mechanical complications", "dental implants", "screw complications", "edentulous arch", "technical complications", "technical complications". "Fracture of metal structure", "restoration", "acrylic veneer fracture", "ceramic veneer fracture", "biological complications" and "edentulous arch". Results: from the 181 articles retrieved, only 3 studies fullfi lled the inclusion criteria for this review, being prospective studies. Such biological and technical complications in implants and prostheses were identifi ed and recorded, including: structure/veneering material fractures, prosthetic screw loosening and/or abutment screw, prosthetic and/or abutment screw fracture, defi cient esthetics, and material wear. Conclusion: within the limits of this systematic review, studies on ceramic materials with 5 years of follow-up are scarce or non-existent suggesting caution in the use of this type of implant-supported restoration.

Research progress in CoCr metal-ceramic alloy fabricated by selective laser melting / 中华口腔医学杂志

Cobalt-chromium alloys have been applied to dental porcelain fused to metal (PFM) restorations over the past decades owing to their excellent corrosion resistance, good biocompatibility and low price. The production of CoCr metal-ceramic restorations has always been based on traditional lost-wax casting techniques. However, in recent years, selective laser melting (SLM) is becoming more and more highly valued by dental laboratories and dental practitioners due to its individuation, precision and efficiency. This paper mainly reviews the recent researches on the production process of copings, microstructure, mechanical property, metal-ceramic bond strength, fit of copings, corrosion resistance and biocompatibility of SLM CoCr metal-ceramic alloy.

Metal-ceramic bond strength between a feldspathic porcelain and a Co-Cr alloy fabricated with Direct Metal Laser Sintering technique

PURPOSE: The aim of the present study was to record the metal-ceramic bond strength of a feldspathic dental porcelain and a Co-Cr alloy, using the Direct Metal Laser Sintering technique (DMLS) for the fabrication of metal substrates. MATERIALS AND METHODS: Ten metal substrates were fabricated with powder of a dental Co-Cr alloy using DMLS technique (test group) in dimensions according to ISO 9693. Another ten substrates were fabricated with a casing dental Co-Cr alloy using classic casting technique (control group) for comparison. Another three substrates were fabricated using each technique to record the Modulus of Elasticity (E) of the used alloys. All substrates were examined to record external and internal porosity. Feldspathic porcelain was applied on the substrates. Specimens were tested using the three-point bending test. The failure mode was determined using optical and scanning electron microscopy. The statistical analysis was performed using t-test. RESULTS: Substrates prepared using DMLS technique did not show internal porosity as compared to those produced using the casting technique. The E of control and test group was 222 ± 5.13 GPa and 227 ± 3 GPa, respectively. The bond strength was 51.87 ± 7.50 MPa for test group and 54.60 ± 6.20 MPa for control group. No statistically significant differences between the two groups were recorded. The mode of failure was mainly cohesive for all specimens. CONCLUSION: Specimens produced by the DMLS technique cover the lowest acceptable metal-ceramic bond strength of 25 MPa specified in ISO 9693 and present satisfactory bond strength for clinical use.

Effect of different sandblasting conditions on the metal-ceramic bonding strength of Co-Cr alloy fabricated by selective laser melting technology / 华西口腔医学杂志

OBJECTIVE@#To investigate the effect of different sandblasting conditions on the metal-ceramic bonding strength of Co-Cr alloy fabricated by selective laser melting (SLM) technology.@*METHODS@#A total of 63 specimens of Co-Cr alloy fabricated by SLM were prepared and randomly divided into nine groups (n=7). Each group was treated with different powder particles (A1=50 µm, A2=100 µm, and A3=150 µm) and pressures (B1=0.2 MPa, B2=0.4 MPa, and B3=0.6 MPa) in sandblasting. One sample was randomly selected from each group for microstructure observation by scanning electron microscope (SEM). Ceramic was fired at the center of the specimens. Metal-ceramic bonding strength was measured with universal testing machine. Results were statistically analyzed with SPSS 17.0 software.@*RESULTS@#The mean bond strengths were as follows: Group A1B1: 27.22 MPa±0.95 MPa, Group A1B2: 27.58 MPa±0.47 MPa, Group A1B3: 26.80 MPa±0.71 MPa, Group A2B1: 27.54 MPa±0.78 MPa, Group A2B2: 30.75 MPa±0.43 MPa, Group A2B3: 26.93 MPa±0.88 MPa, Group A3B1: 28.18 MPa±0.93 MPa, Group A3B2: 29.55 MPa±0.57 MPa, and Group A3B3: 28.11 MPa±0.91 MPa. The particle factor of Al₂O₃ and the pressure factor of blasting showed statistical significance (P<0.05). An interaction was observed between the factors of particle and pressure (P<0.05). Mixed fracture mode of all specimens was observed after the shear strength test.@*CONCLUSIONS@#In conclusion, metal-ceramic bonding strength reaches the maximum when specimens are sandblasted with 100 µm alumina oxide at 0.4 MPa pressure.

Clinical effect of zirconia all-ceramic crown on repairing the anterior teeth and its influence on the quality of life of patients / 中国基层医药

Objective To investigate the clinical effect of zirconia all -ceramic crown for anterior teeth restoration,and its influence on the quality of life .Methods Eighty-four patients with anterior teeth repair [4 cases were lost during the follow-up,and there were 80 cases (106 teeth)] were selected.According to different surgical methods,they were divided into control group (56 teeth) and study group (50 teeth).The control group used Ni Cr alloy porcelain crown,the study group used two zirconia all -ceramic crown.The patients were followed up for 1 year, the repair effect ,incidence rate of adverse reactions and quality of life score were compared between the two groups .Results After 1 year of crown restoration , the color, integrity, edge coloring in the study group were significantly better than those in the control group(all P<0.05).The incidence rate of adverse reactions such as gingivitis ,peri-odontitis,root fracture,allergies of the study group was 7.5%,which was significantly lower than 45.0%of the control group(χ2 =5.129,P<0.05).There were no statistically significant differences in quality of life scores between the two groups before repair(all P>0.05).The quality of life scores in the study group after repair were significantly higher than those in the control group (t=18.623,22.389,20.724,10.190,all P<0.05).Conclusion The clinical effect of zirconia all-ceramic crown for anterior teeth restoration is better .It can improve the aesthetic effect ,safety and quality of life score of patients .It is worthy of popularizing and application in clinic .

Comparison of the applicatied effect of two kinds of post core porcelain fused to metal crown for restoration of residual crown of first molar / 中国基层医药

Objective To compare the applicatied effect of two kinds of post core porcelain fused to metal crown for restoration of residual crown of first molar .Methods 52 patients with residual crowns of first molars (98 teeth) were selected.According to the random numerical table method ,they were divided into group A[post core crown of metal casting in 27 cases ( 49 teeth ) ] and group B [ post core crown of screw thread amalgam in 25 cases (49 teeth)].After a year of follow -up,the success rate of the two groups was compared .Results Metal casting core crown pile was broken at 0 in group A and at 3 in group B,the success rate of group A was 93.88％,and the success rate of group B was 79.59％,the difference was statistically significant between the two groups (χ2 =4.346, P<0.05).Conclusion The retention,resistance and durability of post core crown of metal casting is far superior to post core crown of screw thread amalgam ,and it is a more ideal repair method .

Dissilicato de lítio: como potencializar a tenacidade a fratura clinicamente? / Lithium disilicate: how to potentiate fracture toughness clinically?

As restaurações indiretas metalocerâmicas têm um largo tempo de acompanhamento clínico com alta taxa de sucesso. Contudo, a mudança na escala de valores dos conceitos estéticos e o apelo por um comportamento socioeconômico que transmita maior confiança e autoestima têm procurado substituir tais materiais. O grande problema da infraestrutura metálica é o chamado "sorriso metalocerâmico" que expõe a cinta metálica após recessão da margem gengival, constituindo-se fator indesejável. Visando contornar esse problema, aprimoramentos técnico-científicos têm procurado substitutos, tais como as coroas com ombros cerâmicos "colar-less"1,2, 3, até o aprimoramento de novos sistemas vitro-cerâmicos com aumento do conteúdo de cristais que visam impedir a propagação de trincas, aumentando a tenacidade dessas estruturas e melhorando sua resistência mecânica. Entre os novos sistemas cerâmicos, os que empregam o dissilicato de lítio voltaram a ser explorados pela gama de aplicações clínicas, principalmente nos fragmentos cerâmicos e lentes de contato tão em moda. Sendo a tenacidade à fratura componente importante na escolha do sistema cerâmico, este trabalho tem o objetivo de esclarecer os reais mecanismos envolvidos na escolha do dissilicato de lítio como opção clínica para a confecção de restaurações indiretas contemporâneas

The metal-ceramics indirect restorations have a square time of clinical attendance with high success rates. However, the change in the scale of values of aesthetic concepts and the appeal for a socioeconomic behavior that transmits larger trust and selfconfidence have been trying to substitute such materials. The great problem of the metallic infrastructure is the called "metal-ceramic smile" that exposes the metallic colar after gingival margin recession, being constituted undesirable factor. Aiming to outline that problem, technician-scientific improvements have been seeking substitutes such as: the crowns with ceramic shoulders "colar-less" 1, 2, 3, until the improvement of new systems glass-ceramics with increase of crystals content to impede cracks propagation, increasing the fracture toughness values of those structures and improving their mechanical resistance. Among new ceramic systems, those that use lithium disilicate were explored by the range of clinical applications again, mainly in ceramic fragments and dental veneers so in fashion. Being the fracture toughness to important component in the choice of ceramic system, this work has the objective to explain the real mechanisms involved in the choice lithium disilicate as clinical option to make contemporary indirect restorations

Comparison of the bond strength of ceramics to Co-Cr alloys made by casting and selective laser melting

PURPOSE: Considering the importance of metal-ceramic bond, the present study aimed to compare the bond strength of ceramics to cobalt-chrome (Co-Cr) alloys made by casting and selective laser melting (SLM). MATERIALS AND METHODS: In this in-vitro experimental study, two sample groups were prepared, with one group comprising of 10 Co-Cr metal frameworks fabricated by SLM method and the other of 10 Co-Cr metal frameworks fabricated by lost wax cast method with the dimensions of 0.5 × 3 × 25 mm (following ISO standard 9693). Porcelain with the thickness of 1.1 mm was applied on a 3 × 8-mm central rectangular area of each sample. Afterwards, bond strengths of the samples were assessed with a Universal Testing Machine. Statistical analysis was performed with Kolmogorov-Smirnov test and T-test. RESULTS: Bond strength in the conventionally cast group equaled 74.94 ± 16.06 MPa, while in SLM group, it equaled 69.02 ± 5.77 MPa. The difference was not statistically significant (P ≤ .05). CONCLUSION: The results indicated that the bond strengths between ceramic and Co-Cr alloys made by casting and SLM methods were not statistically different.

Degradação Adesiva de um Compósito Auto Aderente aos Substratos da Técnica Indireta / Bonding Degradation of a Self-Adhering Composite to Substrates used in Indirect Technique

O objetivo desse estudo foi avaliar a resistência de união - RU ao cisalhamento de um compósito fluido auto aderente em quatro substratos utilizados na técnica indireta, com uma semana e um ano de armazenamento em água destilada. Quarenta e oito amostras (5 mm largura / 15 mm comprimento / 2 mm espessura) foram preparadas em laboratório protético: 12 amostras do(a) cerômero Adoro/AD, cerâmica/leucita Empress Esthetic/EE, cerâmica/zircônia ZirCAD/ZI (Ivoclar Vivadent), mais a liga Fit Cast SB/ME (Talladium do Brasil), sendo as amostras divididas em dois grupos para cada período de tempo (uma semana e um ano). Dois compósitos fluidos (Controle / FF-Filtek Z350XT Flow / 3M ESPE e o auto aderente / DF-Dyad Flow / Kerr) foram unidos aos quatro substratos. Quatro matrizes Tygon foram posicionadas sobre as amostras, as quais foram preenchidas com os compósitos FF e DF (fotopolimerização 20s). As matrizes foram removidas para expor os corpos de prova (12 por grupo) e as amostras foram armazenadas em água destilada/ 37±2 °C por uma semana e um ano. Após estes períodos, cada amostra foi conectada a uma máquina de ensaios para realização dos ensaios de RU a uma velocidade de 1,0 mm/min, até a falha. Os resultados foram analisados por ANOVA e teste de Tukey (p<0,05). Nos ensaios de uma semana, os substratos leucita e metal apresentaram as maiores médias de RU para ambos os compósitos. Nos ensaios de um ano, os substratos não apresentaram diferença estatística nas médias de RU para ambos os compósitos, com exceção da zircônia que apresentou resultado nulo. Os valores médios de RU, no entanto, foram significativamente menores quando comparados com os resultados dos ensaios de uma semana.(AU)

The aim of this study was to evaluate the shear bond strength (SBS) of a self-adhering flowable composite on four substrates used in indirect technique, for a week and one year of storage in distilled water. Forty eight samples (5 mm wide / 15 mm length / 2 mm thick) were prepared at dental prosthetic laboratory: 12 samples of the ceromer Adoro/AD, leucite ceramic IPS Empress Esthetic/EE, zirconia ceramic ZirCAD/ZI (Ivoclar Vivadent) and the metal ceramic alloy Fit Cast SB/ME (Talladium do Brasil). Samples of each substrate were divided into two groups for each time (a week and one year). Two flowable composites (Control/FF-Filtek Z350 XT Flow/3M ESPE, and the self-adhering/DF-Dyad Flow/Kerr) were bonded to four substrates. Four Tygon tubing were positioned over each sample, which were filled in with the composites FF and DF, and visible light-cured for 20s. The tubings were removed to expose the specimens (12 per group) in format of cylinders, and the samples were stored in distilled water at 37 ± 2°C for one week and one year. After these periods, each sample was attached to testing machine and the specimens were submitted to the shear bond strength test at speed of 1.0mm/min, until failure. The results were analyzed by ANOVA and Tukey test (p<0.05). To one week tests, the substrates leucite and metal showed the highest SBS means, to both composites. For the one-year experiments, the substrates did not show differences in the SBS averages for both composites, except for zirconia that showed null result. However, the SBS averages were lower when compared to one week tests.(AU)

Clinical effect of all-ceramic restorations and metal-ceramic restorations:A Meta-analysis / 实用口腔医学杂志

Objective:To evaluate the clinical outcome of all-ceramic and metal-ceramic restorations by means of Meta-analysis. Methods:The relevant randomized controlled trials ( RCTs) were electronically searched from PubMed, the Cochrane Library, EM-base, SinoMed, Weipu databases, CNKI and Wanfang. After data extraction and bias evaluation the Meta-analysis was conducted using RevMan 5. 3 software. Results:Finally 15 RCTs involving 768 all-ceramic restorations and 1386 Metal-ceramic restorations met the eli-gibility criteria. The results showed that, compared with metal-ceramic restorations, all-ceramic restorations could significantly decrease the risk of gingivitis(RR=0. 30,95%CI=0. 10-0. 90, P=0. 03),could decrease secondary caries and improve the satisfaction of cervical discoloration and marginal adaptation but without significant difference. There was no difference in color match and chipping of the veneering ceramics. However, all-ceramic restorations may lead to loss of the abutment tooth vitality. The risk of all-ceramic frame-work fracture while adopting fixed bridges was significantly higher(RR=6. 24, 95%CI=1. 20 -32. 41, P=0. 03). Conclusion:Based on the existing limited evidence,the efficacy of all-ceramic restorations is better than metal-ceramic restorations. But the intensity of all-ceramic bridges needs to be improved.

Masking ability of opaque thickness on layered metal-ceramics

This study evaluated the masking ability of two opaques applied in different thicknesses. Eighty NiCr metal discs 16 mm in diameter and 1.0 mm thick were prepared. The disks were divided into 8 groups (n = 10). Ceramic opaque in paste (groups 1 to 4) or powder (groups 5 to 8) presentations were applied. They were machined with aluminum oxide burs to the following thicknesses: G1 and G5 = 0.10 mm; G2 and G6 = 0.15 mm; G3 and G7 = 0.20 mm and G4 and G8 = 0.30 mm. Dentin ceramic 0.7 mm thick was applied over these discs, sintered and glazed according manufacturer’s instructions. Color was assessed with a Minolta CR10 spectrocolorimeter on the CIELab scale. Powder opaque had higher values on (L) and (ΔE) variables, and lower values on (a) and (b) variables compared to paste opaque. For opaque thickness, 0.10 mm had higher ΔE than all other thicknesses. L values were higher for 0.20 mm and 0.30 mm. Lowest and highest a* values were observed for 0.10 mm and 0.30 mm, respectively. No difference was observed for b* values. There were differences between paste and powder opaque types; 0.10 mm thickness behaves differently from the other thicknesses, with higher ΔE, while 0.15 mm does not differ statistically from thicker layers.

O objetivo deste estudo foi avaliar a capacidade de mascara mento de duas cerâmicas opacas para metalocerâmicas aplicadas em espessuras diferentes. Foram confeccionados 80 discos metálicos de NiCr (High Bond) com 16 mm de diâmetro e 1,0 mm de espessura. Os discos foram divididos em 8 grupos (n=10) e aplicadas as cerâmicas opacas (Noritake) em pasta (grupos de 1 a 4) e em pó (grupos de 5 a 8). Estas foram usinadas com pontas de óxido de alumínio até atingir as seguintes espessuras: G1 e G5 = 0,10 mm; G2 e G6 = 0,15 mm; G3 e G7 = 0,20 mm e G4 e G8 = 0,30mm de espessura. A cerâmica de dentina opaca foi aplicada (0,7 mm) e realizado o glazeamento. A cor foi avaliada com Espectrocolorímetro (Minolta CR10) e foi aplicada análise de variância com para p<5%. Resultados: O opaco em pó apresentou valores maiores estaticamente significantes nas variáveis (L*) e (ΔE), ocorrendo o inverso nas outras duas variáveis. Quanto à espessura de opaco, os valores podem ser agrupados da seguinte forma, segundo os testes complementares aplicados: variável (L*): (0,10 = 0,15) < (0,20 = 0,30); variável (a*): (0,10) < (0,15 = 0,20) < (0,30); variável (b*): não houveram diferenças estatisticamente significantes; variável (ΔE): (0,10)< (0,15 = 0,20 = 0,30). Conclui-se que houve diferença entre os tipos de opaco em pasta e em pó e que todas as espessuras testadas, exceto a de 0,10 mm, podem ser usadas sem alteração significativa da cor.

Effects of core characters and veneering technique on biaxial flexural strength in porcelain fused to metal and porcelain veneered zirconia

PURPOSE: The purpose of this study was to assess the impact of the core materials, thickness and fabrication methods of veneering porcelain on prosthesis fracture in the porcelain fused to metal and the porcelain veneered zirconia. MATERIALS AND METHODS: Forty nickel-chrome alloy cores and 40 zirconia cores were made. Half of each core group was 0.5 mm-in thickness and the other half was 1.0 mm-in thickness. Thus, there were four groups with 20 cores/group. Each group was divided into two subgroups with two different veneering methods (conventional powder/liquid layering technique and the heat-pressing technique). Tensile strength was measured using the biaxial flexural strength test based on the ISO standard 6872:2008 and Weibull analysis was conducted. Factors influencing fracture strength were analyzed through three-way ANOVA (alpha< or =.05) and the influence of core thickness and veneering method in each core materials was assessed using two-way ANOVA (alpha< or =.05). RESULTS: The biaxial flexural strength test showed that the fabrication method of veneering porcelain has the largest impact on the fracture strength followed by the core thickness and the core material. In the metal groups, both the core thickness and the fabrication method of the veneering porcelain significantly influenced on the fracture strength, while only the fabrication method affected the fracture strength in the zirconia groups. CONCLUSION: The fabrication method is more influential to the strength of a prosthesis compared to the core character determined by material and thickness of the core.

Endodontic and Esthetic Management of Hypolplastic Turner’s Teeth with Severely Dilacerated Roots.

Dilaceration refer to an angulation or sharp bend or curve in the root or crown of formed tooth. It is usually occur due to trauma that lead to white or yellow brown discoloration, crown dilaceration, root dilacerations, crown duplication, root duplication, odontoma like malformation etc. This paper elaborated a useful clinical considerations for diagnosis and treatment planning of a severely dilacerated root of malformed tooth having turner’s hypoplasia.

IPS e. max Press porcelain crown in esthetic restoration of anterior teeth:a follow-up of marginal adaptation and color match / 中国组织工程研究

BACKGROUND:IPS e. max Press porcelain crown has been widely used in clinical restoration because of its aesthetic effect and biological properties. OBJECTIVE:To explore the effect of IPS e. max Press porcelain crown in esthetic restoration of anterior teeth in terms of marginal adaptation and color match. METHODS:Total y 52 patients with 138 defective anterior teeth (20 males and 32 females, 18-45 years old, including 62 anterior tooth defects, 46 tooth traumas, 30 denticles) were divided into two groups randomly:treatment group (26 cases) and control group (26 cases) were given IPS e.max Press porcelain crown and conditional Co-Cr al oy handcuffed ceramic crowns, respectively. Al the cases were asked for a second visit in 1 week after restoration, and the integrity of ceramic veneer, marginal adaptation, gingival health and color match were evaluated during 6-month and 2-year fol ow-ups. RESULTS AND CONCLUSION:The degrees of satisfaction on the color, shape and adaptation in the treatment group were al higher than those in the control group (P<0.05). At 6 months after restoration, the marginal adaptation, gingival health and color match in the treatment group were al better than those in the control group (P<0.05). At 2 years after restoration, there was also a significant difference in the marginal adaptation, gingival health and color match between the two groups (P<0.05). IPS e.max Press porcelain crown has the advantages of aesthetics and biological characteristics, so it can be used as an ideal restoration method for esthetic restoration of anterior teeth.