Effect of handling material on mechanical and optical properties of feldspathic porcelain.

OBJECTIVE: To evaluate the optical, chemical, and mechanical properties of feldspathic porcelain after handling with different instrument materials. MATERIAL AND METHODS: Feldspathic porcelain was manipulated with different spatula compositions: metal spatula (MS), plastic spatula (PS), and glass spatula (GS) for the fabrication of 30 (n = 10) disks. Contrast ratio (CR), translucency parameter (TP), and surface Knoop microhardness (KHN) were measured. The color change (ΔE00 ) was evaluated using the CIEDE2000 system. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) were used for surface analysis. Data were analyzed using one-way ANOVA and Tukey test (P < 0.05). RESULTS: All groups presented different morphological surfaces with higher presence of Al on the MS. PS group presented lower Al, Si, K than MS, and GS. Higher CR was observed for PS (0.734; P < 0.043), followed by MS (0.696; P < 0.043) and GS (0.65; P < 0.011). The highest TP (13.06) and KHN (386.27) were presented by GS (P < 0.001). MS and PS presented similar KHN results. The higher ΔE00 were found for plastic/metal comparison. Also, the L* values for the MS group (67.49) were lower than the other groups. CONCLUSION: The use of metal spatula promoted higher color alteration during feldspathic porcelain manipulation than did the other materials. Handling with glass instrument promoted higher microhardness than other spatula materials. CLINICAL SIGNIFICANCE: The effect of the material used for ceramic handling on feldspathic porcelain properties is often ignored. This study shows that the handling spatula material must be carefully chosen to avoid inadvertent changes to the feldspathic porcelain restoration.

Review of nano-technology applications in resin-based restorative materials.

OBJECTIVE: Nanotechnology has progressed significantly and particles as small as 3 nm are being employed in resin-based restorative materials to improve clinical performance. The goal of this review is to report the progress of nanotechnology in Restorative Dentistry by reviewing the advantages, limitations, and applications of resin-based restorative materials with nanoparticles. MATERIALS AND METHODS: A literature review was conducted using PubMed/Medline, Scopus and Embase databases. In vitro, in vivo and in situ research studies published in English between 1999 and 2020, and which focused on the analysis of resin-based restorative materials containing nanoparticles were included. RESULTS: A total of 140 studies were included in this review. Studies reported the effect of incorporating different types of nanoparticles on adhesive systems or resin composites. Mechanical, physical, and anti-bacterial properties were described. The clinical performance of resin-based restorative materials with nanoparticles was also reported. CONCLUSIONS: The high surface area of nanoparticles exponentially increases the bioactivity of materials using bioactive nanofillers. However, the tendency of nanoparticles to agglomerate, the chemical instability of the developed materials and the decline of rheological properties when high ratios of nanoparticles are employed are some of the obstacles to overcome in the near future. CLINICAL SIGNIFICANCE: In spite of the recent advancements of nanotechnology in resin-based restorative materials, some challenges need to be overcome before new nano-based restorative materials are considered permanent solutions to clinical problems.

Influence of thickness and aging on the mechanical properties of provisional resin materials.

This study aimed to evaluate the flexural strength (FS) and modulus of elasticity (ME) of 2 provisional resins at different thicknesses and after different storage periods. A total of 80 specimens were made of 2 provisional restorative materials (n = 40): Dencôr (DC) or Protemp 4 (PT). The specimens in each material group were prepared in 2 different thicknesses (n = 20): 1.5 mm or 2.0 mm. The groups were further subdivided by storage time (n = 10 per material thickness per time): 7 days or 3 months. A 3-point bending test was performed with a universal testing machine. Data were submitted to 3-way analysis of variance followed by a post hoc Tukey test (α = 0.05). Regarding the interaction of material and thickness, the 2.0-mm-thick DC specimens presented a significantly lower mean FS (41.08 MPa) than the other groups (P < 0.05). Regarding the interaction of material and storage time, PT after 3 months presented a significantly higher mean FS (75.51 MPa) than the other groups and periods (P < 0.05). Regardless of the material, the highest mean ME was found in the 1.5-mm-thick group after 3 months (2.24 GPa) (P < 0.05). The lowest ME values were found in the 2.0-mm-thick specimens after both storage times (7 days, 0.88 GPa; 3 months, 1.09 GPa), which were not significantly different from each other (P > 0.05). The correlation between FS and ME was direct and positive (R2 = 0.51; P < 0.001), independently of the variables (material, thickness, and time). Therefore, 2.0-mm-thick PT specimens presented the highest values of FS, mainly after 3 months. The ME was higher after 3 months (1.5-mm-thick specimens), regardless of the material. In addition, the higher the FS, the higher the ME of the material.

Marginal and internal adaptation of lithium disilicate partial restorations: A systematic review and meta-analysis.

AIM: The aim of this meta analysis was to evaluate the influence of the processing method on the marginal and internal gaps of lithium disilicate inlays/onlays. SETTINGS AND DESIGN: A systematic literature review was conducted using the PubMed/Medline, Embase, Scopus, and Cochrane Library databases. This review was registered on the PROSPERO platform. MATERIALS AND METHODS: The studies were selected according to the marginal and internal gaps of two different fabrication methods for lithium disilicate (milled and pressed). STATISTICAL ANALYSIS USED: The meta analysis was performed based on the Mantel-Haenszel and inverse variance methods, using the random effects model and a 95% confidence interval. RESULTS: From all databases, 127 studies were identified. Four in vitro studies were included in the qualitative analysis and three in the meta analysis. Moreover, 197 restorations were evaluated (103 pressed and 94 milled). During the evaluation of only the internal gap, there was a statistically significant difference favoring the pressed technique (P = 0.002). There was no statistically significant difference in the analyses of the marginal gap (P = 0.530) and the total gap (P = 0.450). CONCLUSION: Both the techniques provided acceptable marginal and total gaps, although the pressed technique revealed a more favorable internal adaptation than the milled onlays/inlays.

Influence of the ferrule effect on the failure of fiber-reinforced composite post-and-core restorations: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: The survival and/or success of post-retained restorations is influenced by the amount of residual coronal structure, known as the "ferrule effect." PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate whether the presence or absence of the ferrule effect influences the failure rate of fiber-reinforced composite post-and-core restorations. MATERIAL AND METHODS: A comprehensive review of the literature was performed using the PubMed/Medline, Embase, Scopus, and Cochrane Library databases for articles published up to May 2018. The risk ratio with 95% confidence interval was estimated using the Mantel-Haenszel method. Potentially eligible studies were selected based on the reading of the abstracts and full text of prospective clinical trials, randomized clinical trials, or prospective randomized studies, all with a minimum of 10 participants in each group, with a follow-up period longer than 6 months, and published in English. RESULTS: Of the 380 studies retrieved, 4 were included in this meta-analysis. A total of 297 teeth were evaluated, 157 with a ferrule and 140 without a ferrule. The mean survival rate was 88.35% in the ferrule group and 78.05% in the nonferrule group. No statistically significant difference was noted in the general failure analysis (risk ratio: 0.71 [95% confidence interval: 0.47 to 1.06]; P=.09), although a higher number of failures occurred in nonferrule restorations. More controlled and randomized clinical trials are needed to establish a clinical protocol for the use of post-retained restorations. CONCLUSIONS: Despite the limited number of available studies, the results of this meta-analysis suggest that the ferrule effect does not significantly reduce the failure rate in fiber-reinforced composite post-and-core restorations.

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

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.

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.

Clinical performance of the composite resin veneers: the minimally invasive approach / Desempenho clínico de facetas de resina composta: uma abordagem minimamente invasiva / Desempeño clínico de las carillas de resina compuesta: un enfoque mínimamente invasivo

Minimally invasive approach lead composite resin veneers restorations as a conservative and alternative treatment option, with the aim to improve the aesthetics anterior dentition. Clinically, this treatment reducing the clinical time and has a lower cost than indirect technique. In addition, new resin composite was developed to support the clinician to make more natural restorations. The present case report aim to evaluated the clinical performance of direct composite veneer technique was restored with 100% supra-nano spherical filler composite. A 39-year-old female, searched for restorative treatment of anterior teeth, which were unaesthetically altered. In the clinical examination, it was observed color alterations in maxillary left and right incisors and canines due to use of medicines, and bruxism. The treatment plan included an in-office dental bleaching, removal of inadequate anterior restorations and confection of composite veneers restorations. The dental bleaching was performed with hydrogen peroxide 35% activated by LED/laser in two sessions. Those restorations were performed using supra-nano spherical resin-based composite, color A1 for dentin and enamel, with direct composite laminate veneer technique. After six-month follow-up, the restorations presented good clinical aspect, absence of biofilm accumulation and abrasive wear. Therefore, direct veneer restorations may be alternative treatment for anterior teeth esthetic problems, suggesting a promising performance of these new composites(AU)

A abordagem minimamente invasiva torna as facetas de resina composta conservadoras e opção de tratamento alternativo para melhorar a estética da dentição anterior. Clinicamente, esse tratamento reduz o tempo operatório e tem um custo menor que a técnica indireta. Além disso, uma nova resina composta foi desenvolvida para ajudar o clínico a fazer restaurações mais naturais. O presente relato de caso tem como objetivo avaliar o desempenho clínico da técnica direta de faceta de resina composta de preenchimento 100% supra-nano-esférico. Paciente de 39 anos, sexo feminino procurou o tratamento restaurador dos dentes anteriores, que foram alterados inesteticamente. No exame clínico foram observadas alterações de cor nos incisivos superiores, esquerdo e direito, e caninos devido ao uso de medicamentos e bruxismo. O plano de tratamento incluiu clareamento dentário em consultório, remoção de restaurações anteriores inadequadas e confecção de facetas de resina composta. O clareamento dental foi realizado com peróxido de hidrogênio a 35% ativado por LED / laser em duas sessões. Essas restaurações foram realizadas utilizando resina composta supra-nano-esférica, cor A1 para dentina e esmalte, com técnica direta de laminado composto. Após seis meses de acompanhamento as restaurações apresentaram bom aspecto clínico, ausência de acúmulo de biofilme e desgaste abrasivo. Portanto, facetas diretas de resina composta podem ser um tratamento alternativo para problemas estéticos de dentes anteriores, sugerindo um desempenho promissor desses novos compósitos(AU)

El abordaje mínimamente invasivo hace que las facetas de resina compuesta conservadoras y opción de tratamiento alternativo para mejorar la dentición anterior estética. Clínicamente, este tratamiento reduce el tiempo clínico y tiene un costo menor que la técnica indirecta. Además, un nuevo compuesto de resina fue desarrollado para ayudar al clínico a hacer restauraciones más naturales. El presente relato de caso tiene como objetivo evaluar el desempeño clínico de la técnica directa de faceta de resina compuesta de relleno 100% supra-nano-esférico. Paciente de 39 años, sexo femenino buscó el tratamiento restaurador de los dientes anteriores, que fueron alterados intemporal. En el examen clínico se observaron alteraciones de color en los incisivos superiores, izquierdo y derecho, y caninos debido al uso de medicamentos y bruxismo. El plan de tratamiento incluyó blanqueamiento dental en consultorio, remoción de restauraciones anteriores inadecuadas y confección de facetas de resina compuesta. El blanqueamiento dental fue realizado con peróxido de hidrógeno al 35% activado por LED / láser en dos sesiones. Estas restauraciones se realizaron utilizando resina compuesta supra-nano esférica, color A1 para dentina y esmalte, con técnica directa de laminado compuesto. Después de seis meses de seguimiento las restauraciones presentaron buen aspecto clínico, ausencia de acumulación de placa dental y desgaste abrasivo. Por lo tanto, las facetas directas de resina compuesta pueden ser un tratamiento alternativo para problemas estéticos de dientes anteriores, sugiriendo un desempeño prometedor de estos nuevos compuestos(AU)

Understanding the interaction of resin composite with light for predictable aesthetic results in anterior teeth: A case report / Compreensão da interação das resinas compostas com a luz para resultados estéticos previsíveis em dentes anteriores: Relato de caso

This case report illustrates a conservative technique for reintervention on anterior composite restorations in a young patient with composite veneers. The treatment incorporated the use of photos and digital planning to establish a harmonious smile design. In order to conserve the dental tissues, existing resin composites restorations in maxillary anterior teeth were carefully removed to minimize enamel reduction, followed by a study of color and shade of teeth considering factors such as hue, chroma, luminosity, opacity, translucency and light effects. Eight direct veneers were built up with resin composite taking the optical properties of the material into account and their influence on the thickness of the layers that create specific light effects when superimposed on each other. To obtain excellent results with a predictable working protocol, nanohybrid composite systems facilitate good aesthetics, avoiding more invasive treatment in an economic manner.(AU)

O presente relato de caso ilustra uma técnica conservadora para a re-intervenção em restaurações diretas de resina composta em pacientes jovens. O tratamento consistiu em fotos e planejamento digital para obtenção de um desenho digital do sorriso individual e harmonioso. De acordo com os princípios de máxima conservação da estrutura dentária, as restaurações existentes nos dentes superiores anteriores foram criteriosamente removidas para minimizar a redução do esmalte, seguido do estudo de cor e sombra dos dentes considerando fatores como matiz, croma, valor, opacidade, translucidez e efeitos de luz. Oito facetas diretas foram realizadas em resina composta considerando as propriedades ópticas do material e a influência destas na espessura das camadas de resina para criar efeitos de luz singulares quando sobrepostas. Para a execução de uma odontologia estética e consciente, em associação a um protocolo de trabalho previsível, os sistemas de resinas compostas nanohibridas possibilitam resultados estéticos satisfatórios, evitando tratamentos mais invasivos de maneira economicamente viável.(AU)

Ainda é necessário criar rugosidade na superfície da Y-TZP? / Is it still necessary to roughen the Y-TZP surface?

Problematização. As Zircônias tetragonais estabilizadas com ítria (Y-TZP) são amplamente utilizadas na confecção de próteses dentárias. Uma vez que é mais utilizada como infraestrutura, as cerâmicas de cobertura ainda mostram fraturas, resultando em redução da longevidade da prótese. Objetivo. Avaliar e testar a eficácia de tratamentos de superfície entre Y-TZP e cerâmica de cobertura antes da aplicação do liner. Material e métodos. Quarenta discos Y-TZP (12,5mm de diâmetro e 3,5mm de espessura) foram divididos em quatro grupos (n = 10): LC: aplicação exclusiva do liner; S40: sonicação pré-sinterizada com 40 % de potência nominal durante 15 minutos; S70: sonicação présinterizada com 70 % de potência nominal durante 15 minutos; JOX: jateamento com partículas de alumínio de 50µm. Após os tratamentos rugosos de superfície, o liner foi aplicado na superfície das amostras todos os grupos. Após a sinterização, os espécimes foram submetidos a Microscopia confocal de varredura a laser (CLSM) e Microscopia de força atômica (AFM) para avaliar a topografia e a rugosidade da superfície. As fases das estruturas cristalinas foram identificadas através de espectroscopia micro-Raman (MRS). Após esta etapa, a cerâmica de cobertura foi aplicada em todas as superfícies da Y-TZP e os espécimes foram submetidos ao teste de Resistência de união ao cisalhamento (SBS) a uma velocidade de 0,5mm/min até à fratura. Os modos de falha foram classificados como adesiva, coesiva ou mista. Os resultados de SBS foram submetidos a uma ANOVA a um critério (α = 0,05) seguido pelo teste de Tukey (α = 0,05). Resultados. Não foram observadas diferenças entre os grupos quanto à rugosidade superficial (0,255), embora as imagens da Microscopia Confocal e AFM apresentassem diferenças topográficas entre os grupos. O grupo LC apresentou maiores valores medianos de SBS, significativamente diferentes de S70 e JOX (p=0,008), os quais não foram diferentes. S40 apresentou os valores medianos de SBS mais baixos (15,43 Mpa). Todos os espécimes Y-TZP exibiram bandas típicas tetragonais e fases monoclínicas. A maioria dos espécimes de todos os grupos exibiram falhas mistas (67,5%) e os espécimes restantes exibiram falhas adesivas. Conclusão. Tratamentos de superfície adicionais para Y-TZP, jateamento e tratamento sonoquímico com potência de 70 % mostraram resultados semelhantes, mas não aumentaram a SBS para uma cerâmica de cobertura.(AU)

Statement of the problem. The yttria-stabilized tetragonal zirconia (Y-TZP) ceramics are widely used manufacturing of dental prostheses. Since it is most used as framework, the ceramics veneers still show fractures, resulting in reduction of longevity of the prosthesis. Objective. Evaluate and test the effectiveness of roughening treatments between Y-TZP and veneering ceramic before liner application. Material and methods. Forty Y-TZP discs (12.5mm Ø and 3.5mm thickness) were divided in four groups (n = 10): LC: application of the proprietary liner only; S40: pre-sintered sonication with 40 % nominal power for 15 minutes; S70: pre-sintered sonication with 70 % nominal power for 15 minutes; JOX: sandblasting with 50 µm aluminum particles. After roughening treatments, the liner was applied to the surface of the samples in all groups. After sintering, the specimens were subjected to confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM) analyses to evaluate the topography and surface roughness. The phases of the crystalline structures were identified through micro-Raman spectroscopy (MRS). After that, a veneering ceramic was applied to all Y-TZP surfaces and subjected to shear bond strength (SBS) testing at a speed of 0,5mm/min until fracture. Failure modes were classified as adhesive, cohesive, or mixed. SBS results were subjected to one-way ANOVA (α = 0.05) followed by Tukey's test (α = 0.05). Results. No differences were shown between groups regarding surface roughness (p=0,255), although Confocal and AFM images showed topographical differences among groups. The LC group showed the highest SBS median values, which were significantly different from S70 and JOX (p=0,008), which were not different. S40 showed the lowest SBS median values (15,43 MPa). All specimens exhibited typical Y-TZP tetragonal bands and monoclinic phases. Most specimens of all groups exhibited mixed failures (67,5%) and the remaining specimens exhibited adhesive failures. Conclusion. Additional surface treatments for Y-TZP, sandblasting, and 70 % power sonochemical treatment showed similar results but did not increase SBS to a feldspathic ceramic.(AU)