Sobrevivência em fadiga de coroas bioinspiradas bilaminadas: estudo in vitro / Fatigue survival rate of bioinspired bilaminar crowns: in vitro study

O objetivo deste estudo foi avaliar o comportamento biomecânico através da resistência à fadiga e análise por elementos finitos de coroas bioinspiradas bilaminadas com infraestruturas modificadas na superfície vestibular (Estudo A) e utilizando diferentes materiais cerâmicos com módulos elásticos distintos (Estudo B). Para isso, foram confeccionados 90 preparos para coroa total em resina epóxi G10, sobre os quais foram preparadas coroas bioinspiradas de acordo com os seguintes grupos: Estudo A - IC (infraestrutura convencional), IME (infraestrutura modificada estratificada) e IMC (infraestrutura modificada cimentada), todas confeccionadas em dissilicato de lítio (infraestrutura) + porcelana (recobrimento); Estudo B ­ DL+LEU (dissilicato de lítio + leucita), LEU+DL (leucita + dissilicato de lítio), CH+DL (cerâmica híbrida + dissilicato de lítio) e CH+LEU (cerâmica híbrida + leucita). Para o Estudo A, todas as infraestruturas foram usinadas; os recobrimentos dos grupos IC e IME foram confeccionados através da estratificação, e os recobrimentos do grupo IMC foram usinados. Já para o Estudo B, todas as peças foram usinadas, de acordo com o material cerâmico de cada grupo. Em seguida, foi realizada a cimentação adesiva dos recobrimentos sobre as infraestruturas (a depender do grupo) e das coroas sobre os preparos utilizando cimento resinoso fotopolimerizável (Variolink Esthetic LC). Após a cimentação, os espécimes foram submetidos ao teste de fadiga cíclica (10.000 ciclos, 20Hz), e como desfecho foram considerados dois eventos, em que o primeiro foi a ocorrência de trinca e/ou lascamento (evento 1) e o segundo foi a falha catastrófica do conjunto (evento 2). Os valores de carga e número de ciclos para falha em que foram observados os eventos 1 e 2 foram utilizados para realizar a análise de sobrevivência de acordo com Kaplan-Meier e Log-Rank (Mantel-Cox; 95%). As marcas de fratura e o modo de falha das coroas foram avaliados e classificados por estereomicroscópio óptico e microscópio eletrônico de varredura. Por fim, foi realizada análise por elementos finitos (FEA) para ambos os estudos, a fim de avaliar a distribuição de tensões sobre as coroas e interface adesiva. Para o Estudo A, os resultados do teste de fadiga mostraram que, considerando o evento 1 (trinca/lascamento), os grupos IC e IMC apresentaram médias de carga fadiga estatisticamente significantes entre si (733,33 N e 913,33 N, respectivamente), enquanto o grupo IME apresentou média superior (1.020 N). O mesmo foi observado para o número de ciclos em fadiga para todos os grupos. Ao considerar o evento 2 (falha catastrófica), os três grupos apresentaram médias estatisticamente semelhantes entre si (~1.028 N). Os resultados de FEA mostraram que o grupo IC concentrou maior tensão de tração do que os grupos IME e IMC. Para o Estudo B, no teste de fadiga, o grupo DL+LEU apresentou a maior média de resistência à fadiga (evento 1: 913,33 N e evento 2: 1033,33 N), enquanto todas as outras combinações de materiais cerâmicos analisadas foram estatisticamente semelhantes entre si, considerando carga e número de ciclos. Com relação ao FEA, os grupos com cerâmica híbrida (CH+DL e CH+LEU) apresentaram menores picos de concentração de tensão na infraestrutura do que os grupos com cerâmicas vítreas (DL+LEU e LEU+DL), porém, em contrapartida, concentraram maior tensão na interface adesiva. Com isso, conclui-se que a utilização da infraestrutura modificada é uma alternativa viável e promissora para tratamentos reabilitadores, apresentando sobrevivência em fadiga e distribuição de tensões satisfatórias. Além disso, a combinação entre uma infraestrutura de dissilicato de lítio e recobrimento de cerâmica a base de leucita corresponde a melhor abordagem considerando a infraestrutura modificada.(AU)

The objective of this study was to evaluate the biomechanical behavior through fatigue resistance and finite element analysis of bilaminar bioinspired crowns with modified infrastructures on the buccal surface (Study A) and using different ceramic materials with different elastic moduli (Study B). For this, 90 preparations were made for a full crown in G10 epoxy resin, on which bioinspired crowns were prepared according to the following groups: Study A - CI (conventional infrastructure), SMI (stratified modified infrastructure) and CMI (cemented modified infrastructure ), all made of lithium disilicate (infrastructure) + porcelain (veneer); Study B ­ LD+LEU (lithium disilicate + leucite), LEU+LD (leucite + lithium disilicate), HC+LD (hybrid ceramic + lithium disilicate) and HC+LEU (hybrid ceramic + leucite). For Study A, all infrastructures were machined; the coverings of the CI and SMI groups were made through stratification technique, and the veneers of the SMI group were machined. For Study B, all pieces were machined, according to the ceramic material of each group. Then, the veneers were cemented into their infrastructures (depending on the group) and crowns were cemented into preparations using light-cured resin cement (Variolink Esthetic LC). After cementing, the specimens were subjected to the cyclic fatigue test (10,000 cycles, 20Hz), and as an outcome two events were considered: the occurrence of cracking and/or chipping (event 1) and catastrophic failure (event 2). The load (N) and number of cycles to failure in which events 1 and 2 were observed were used to perform the survival analysis according to Kaplan-Meier and Log-Rank (Mantel- Cox; 95%). The fracture marks and failure mode of the crowns were evaluated and classified by optical stereomicroscope and scanning electron microscope. Finally, finite element analysis (FEA) was performed for both studies in order to evaluate the stress distribution over the crowns and adhesive interface. For Study A, the results of the fatigue test showed that, considering event 1 (cracking/chipping), the CI and CMI groups presented average to failure that were statistically significant compared to each other (733.33 N and 913.33 N, respectively), while the SMI group showed higher averages (1,020 N). Same pattern was observed for the number of cycles under fatigue for both groups. When considering event 2 (catastrophic failure), the three groups presented statistically similar means (~1,028 N). The FEA results showed that the CI group concentrated greater tensile stress than the CMI and SMI groups. For Study B, in the fatigue test, the LC+LEU group presented the highest average fatigue resistance (event 1: 913.33 N and event 2: 1033.33 N), while all other combinations of ceramic materials analyzed were statistically similar to each other, considering load and number of cycles. Regarding FEA, the groups with hybrid ceramics (HC+LC and HC+LEU) showed lower stress concentration peaks in the infrastructure than the groups with glass ceramics (LC+LEU and LEU+LC), however, on the other hand, concentrated greater tension at the adhesive interface. With this, it is concluded that the use of modified infrastructure is a viable and promising alternative for oral rehabilitation treatments, presenting satisfactory fatigue survival and adequate stress distribution. Furthermore, the combination of a lithium disilicate infrastructure and a leucite-based ceramic coating corresponds to the best approach considering the modified infrastructure.(AU)

Physico-Chemical comparison of four commercially available mineral trioxide aggregates / Comparación fisicoquímica de cuatro mineral trióxido agregados disponibles comercialmente

Abstract To compare the physicochemical composition of 4 MTAs commercially available in Latin America. ProRoot MTA (Dentsply, USA), MTA Angelus (Angelus, Brazil), MTA Flow (Ultradent, USA), and MTA Viarden (Viarden, Mexico) were physically and chemically compared. Scanning electron microscopy (SEM) images were obtained from the MTA powder and the prepared presentations. Energy Dispersive X-Ray Spectroscopy (EDS) analyses were performed by triplicate, to calculate the mass proportion of calcium (Ca), silicon (Si), the Ca/Si proportion among the 4 brands. Thermogravimetric analyses (TGA) were conducted (50ºC-1000ºC), and mass loss and inflection points were calculated for each material. Statistical differences for Ca and Si content were determined by ANOVA (p<0.05). SEM images showed evident differences in the appearance of both the powder and the prepared MTAs among brands. Angelus MTA showed cubic prisms not observed in the other 3 brands. ProRoot MTA and MTA Flow showed similar homogeneous structures. MTA Viarden was the less homogeneous, with random structures (>15um). When comparing the mass proportions of Ca and Si between the 4 powder samples, MTA Viarden showed a significantly lower proportions of both elements when compared with the other brands (p<0.005). TGA análisis showed a similar behavior for ProRoot MTA, MTA Angelus and MTA Flow, with less than 2% mass loss when the 1000C temperature was reached. MTA Viarden showed a mass loss of 9,94% before the 700C, indicating the presence of different content sensible to temperature degradation. The analyzed MTAs demonstrated to vary significantly in their chemical composition and physical characteristics. Clinicians must be aware of the differences between different brands of a same material, and future research should focus on the clinical implications of these differences.

Resumen Comparar la composición fisicoquímica de 4 MTA disponibles comercialmente en América Latina. Se compararon física y químicamente ProRoot MTA (Dentsply, EE. UU.), MTA Angelus (Angelus, Brasil), MTA Flow (Ultradent, EE. UU.) y MTA Viarden (Viarden, México). Se obtuvieron imágenes de microscopía electrónica de barrido (SEM) del polvo de MTA y de las presentaciones preparadas. Los análisis de espectroscopía de dispersión de energía de rayos X (EDS) se realizaron por triplicado para calcular la proporción de masa de calcio (Ca), silicio (Si), la proporción Ca/Si entre las 4 marcas. Se realizaron análisis termogravimétricos (TGA) (50ºC-1000ºC), y se calcularon las pérdidas de masa y los puntos de inflexión para cada material. Las diferencias estadísticas para el contenido de Ca y Si se determinaron mediante ANOVA (p<0,05). Los análisis SEM mostraron diferencias evidentes en la apariencia tanto del polvo como las preparaciones de los MTA, entre las diferentes marcas. MTA Angelus mostró prismas cúbicos no observados en las otras 3 marcas. ProRoot MTA y MTA Flow mostraron estructuras homogéneas similares. MTA Viarden fue el menos homogéneo, con estructuras aleatorias (>15um). Al comparar las proporciones de masa de Ca y Si entre las 4 muestras de polvo, MTA Viarden mostró proporciones significativamente más bajas de ambos elementos en comparación con las otras marcas (p<0,005). El análisis TGA mostró un comportamiento similar para ProRoot MTA, MTA Angelus y MTA Flow, con menos del 2 % de pérdida de masa al alcanzar los 1000 °C de temperatura. El MTA Viarden mostró una pérdida de masa de 9,94% antes de los 700 °C, indicando la presencia de diferentes contenidos sensibles a la degradación por temperatura. Los MTA analizados demostraron diferencias significativas en su composición química y características físicas. Los clínicos deben ser conscientes de las diferencias entre las diferentes marcas de un mismo material, y futuras investigaciones deben enfocarse en las implicaciones clínicas de estas diferencias.

Reabilitação estética anterior em abordagem multidisciplinar: relato de caso / Aesthetic rehabilitation in a multidisciplinary approach: case report

A estética tem um papel importante na aceitação e autoestima das pessoas e, em virtude disso, os pacientes buscam cada dia mais ter um sorriso harmonioso. As reabilitações estéticas devem envolver um planejamento completo, atrelando função e estética, avaliando tamanho dos dentes, perfil e alturas gengivais, altura do sorriso e corredor bucal. Por conta disso, a odontologia nos permite uma série de abordagens terapêuticas diferentes que chegam a resultados satisfatórios para o paciente. Sendo assim, o presente trabalho tem como objetivo descrever um relato de caso de uma paciente com queixa estética do seu sorriso devido à diferentes tonalidades, formas e tamanhos dos dentes. Após anamnese, exame clínico e radiográfico, o plano de tratamento proposto foi de harmonizações periodontal com aumento de coroa e enxerto gengival, além de coroas em cerâmicas de dissilicato de lítio. Dentro desse contexto, mostra-se que uma abordagem multidisciplinar para reabilitação estética e funcional do sorriso é fundamental, a qual nos proporciona equilíbrio e naturalidade entre estética branca e vermelha no resultado do tratamento reabilitador(AU)

Aesthetics plays an important role in people's acceptance and self-esteem and, as a result, patients increasingly seek to have a harmonious smile. Aesthetic rehabilitations must involve a complete planning, linking function and aesthetics, evaluating tooth size, gingival profile and heights, smile height and buccal corridor. Because of this, dentistry allows us a series of different therapeutic approaches that reach satisfactory results for the patient. Therefore, the present work aims to describe a case report of a patient with an aesthetic complaint of her smile due to different shades, shapes and sizes of teeth. After anamnesis, clinical and radiographic examination, the proposed treatment plan was periodontal harmonization with crown augmentation and gingival graft, in addition to lithium disilicate ceramic crowns. Within this context, it is shown that a multidisciplinary approach to the aesthetic and functional rehabilitation of the smile is fundamental, which provides us with balance and naturalness between white and red aesthetics in the result of the rehabilitation treatment(AU)

Reabilitação estética com facetas e coroas cerâmicas em dissilicato de lítio: relato de caso / Aesthetic rehabilitation with ceramic facets and crowns in lithium disilicate: case report

Introdução: A procura pela estética do sorriso é crescente na Odontologia, pois, muitas vezes um sorriso alinhado e periodonto saudável não são o bastante. A cerâmica odontológica apresenta-se como uma ótima possibilidade restauradora, visto o avanço das técnicas de adesão entre o substrato dentário e as cerâmicas, torna-se mais previsível o resultado com este tipo de reabilitação. Objetivo: O presente artigo tem como objetivo descrever um caso clínico com envolvimento de diversos níveis de desgaste dentário para reabilitação estética com cerâmica de dissilicato de lítio. Relato de caso: Paciente 36 anos, gênero feminino, apresentava insatisfação com seu sorriso devido a forma e a alteração de cor dos seus dentes superiores anteriores e pré-molares. O plano de tratamento consistiu em realizar a troca da coroa metalocerâmica por coroa total cerâmica da unidade 14, coroa total cerâmica nas unidades 11, 21 e 22, facetas cerâmicas nas unidades 15, 13, 12, 23, 24 e 25, osteotomia e gengivoplastia das regiões de 2º prémolar superior esquerdo ao 2º pré-molar superior direito, clareamento dental caseiro da arcada inferior e placa oclusal superior de proteção. O material de escolha para a resolução do caso clínico foi a cerâmica vítrea reforçada à base de dissilicato de lítio, pois, possui um índice de refração de luz semelhante à estrutura dentária, sem interferência significativa da translucidez, além de ser passível de cimentação adesiva por se tratar de uma cerâmica ácido sensível e o tamanho do cristal e a sua disposição favorecem o aumento das propriedades mecânicas da restauração. Conclusão: O plano de tratamento realizado permitiu o restabelecimento da função e estética, com reprodução das características dos dentes naturais e promoção da jovialidade e da harmonia no sorriso(AU)

Introduction:The demand for smile aesthetics is growing in Dentistry, because, often a smile aligned and healthy periodontium are not enough. Dental ceramics, presented as an excellent restorative possibility, since the advancement of adhesion techniques between the dental substrate and the ceramics, becomes more predictable the result with this type of rehabilitation. Objective: This article aims to describe a clinical case involving several levels of dental wear for aesthetic rehabilitation with ceramics. Case Report: A 36-year-old female patient presented dissatisfaction with her smile due to the shape and color alteration of her anterior and premolar upper teeth. The treatment plan consisted of exchanging the metal-ceramic crown for the total ceramic crown of unit 14, total ceramic crown in units 11, 21 and 22, ceramic veneers in units 15, 13, 12, 23, 24 and 25, osteotomy and gingivoplasty of the regions from 2nd left upper premolar to 2nd right upper premolar, home tooth whitening of the lower arch and upper occlusal plate of protection. The material of choice for the resolution of the clinical case was the glass ceramic reinforced on the basis of lithium disilicate because it has a refractive index of light similar to the dental structure, without significant interference of translucency, besides being liable to adhesive cementation because it is a sensitive acid ceramic and the size of the crystal and its disposition favor the increase of the mechanical properties of the restoration. Conclusion: The treatment plan performed allowed the restoration of function and aesthetics, with reproduction of the characteristics of natural teeth and promotion of joviality and harmony in the smile(AU)

Sistemas de pulido para restauraciones cerámicas. Revisión de la literatura / Polishing systems for ceramic restorations. Literature review

El pulido es un paso de suma importancia en el flujo de trabajo de las restauraciones cerámicas, después de realizado un ajuste con puntas o piedras diamantadas, ya que disminuye la rugosidad de las superficies tratadas. Esto repercute positivamente en las propiedades mecánicas y ópticas del material. Sin embargo, la poca literatura disponible acerca de este procedimiento hace que sea pasado por alto. Debido a esto, el presente articulo tuvo como objetivo realizar una revisión bibliográfica sobre los diferentes protocolos de pulido para las diversas restauraciones cerámicas de mayor uso: Feldespática, disilicato de litio y zirconia en sus diferentes presentaciones. Se describen aspectos relevantes sobre el pulido mecánico, la rugosidad superficial y los sistemas de pulido actuales para cerámicas.

Polishing is an extremely important step in the workflow of ceramic restorations, after adjustment with diamond burs or stones, as it reduces the roughness of the treated surfaces. This has a positive impact on the mechanical and optical properties of the material; however, the limited literature available about this procedure makes it to be overlooked. Therefore, the aim of this article was to review the literature on the different polishing protocols for the most used ceramic restorations: Feldspathic, lithium disilicate and zirconia ceramics. Relevant aspects on mechanical polishing, surface roughness and current polishing systems for ceramics are described.

Estabilidade de cor de diferentes sistemas cerâmicos fresados no CAD/CAM e polidos com diferentes métodos / Color stability of different ceramic systems milled in CAD/CAM and polished with different methods

A descoloração ou perda de translucidez dos materiais cerâmicos usados em odontologia ainda hoje é um problema, especialmente pelo comprometimento estético. Com o objetivo de comparar a estabilidade de cor, blocos de dissilicato de lítio (IPS e.max CAD HT) e de silicato de lítio reforçado com zircônia (Vita Suprinity HT) fresados no desenho de um disco com dimensões de 1,5 × 7 × 12 mm3 (n = 120) foram preparados usando 3 procedimentos de acabamento de superfície: glaze, polimento mecânico e coloração externa e glaze. Em seguida, cada grupo foi dividido em 2 subgrupos de armazenamento, chá preto e café (n = 10/grupo). As mensurações de cor foram medidas com espectrofotômetro (VITA Easyshade) no estágio inicial e após 1 semana, 2 semanas, 1 mês, 2 meses de armazenamento. As alterações de cor (ΔE) foram calculadas e analisadas estatisticamente usando ANOVA (α < 0,05). Observamos que, para ambos os materiais cerâmicos, o procedimento de glaze apresentou valores de mudança de cor estatisticamente menores do que os outros grupos (p < 0,05) após o armazenamento em ambas as bebidas. Os grupos de dissilicato de lítio apresentaram valores de alteração de cor estatisticamente menores em relação aos grupos de silicato de lítio reforçados com zircônia. Conclui-se que, o glaze sozinho levou a uma maior estabilidade de cor em relação ao polimento mecânico e coloração externa o dissilicato de lítio apresentou maior estabilidade de cor em comparação com o silicato de lítio reforçada com zircônia.

The discoloration or loss of translucency of ceramic materials used in dentistry is still a problem today, especially due to aesthetic compromise. In order to compare color stability, lithium disilicate (IPS e.max CAD HT) and zirconia-reinforced lithium silicate (Vita Suprinity HT) blocks were milled into a disc design with dimensions of 1.5 × 7 × 12 mm3 (n = 120). The specimens were prepared using 3 surface finishing procedures: glaze, mechanical polishing and external staining and glaze. Then, each group was divided into 2 storage subgroups, black tea and coffee (n = 10/group). Color measurements were measured with a spectrophotometer (VITA Easyshade) at the initial stage and after 1 week, 2 weeks, 1 month, 2 months of storage. Color changes (ΔE) were calculated and statistically analyzed using ANOVA (α < 0.05). We observed that, for both ceramic materials, the glaze procedure presented statistically lower color change values ​​than the other groups (p < 0.05) after storage in both beverages. The lithium disilicate groups showed statistically lower color change values ​​than the zirconia-reinforced lithium silicate groups. It is concluded that, glaze alone led to greater color stability compared to mechanical polishing and external staining, lithium disilicate showed greater color stability compared to zirconia-reinforced lithium silicate.

Is the adhesive or mechanical behavior of glass ceramics influenced by the adhesive layer application after etching and silanization? A literature review

Aim: This review investigated the effect of applying an adhesive after surface treatment of glass-ceramics on the bonding, mechanical or clinical behavior. Methods: Studies comparing the adhesive, mechanical or clinical behavior of glass-ceramics, with or without adhesive application after surface treatment, were included. Searches were performed in PubMed, Scopus, and Web of Sciences databases (January 2022), resulting in 15 included studies. Results: Regarding the evaluated outcomes, 13 studies assessed bond strength, 2 studies assessed biaxial flexural strength and 1 study assessed fatigue failure load, while no study evaluating clinical outcomes was included. It was possible to observe that the adhesive application after ceramic surface treatment was unfavorable or did not influence the evaluated outcomes. Conclusion: Most of the evidence available in the literature shows that the adhesive application after surface treatment does not improve the adhesive and mechanical behavior of glass-ceramics

Does low-intensity pulsed ultrasound accelerate phasic calcium phosphate ceramic-induced bone formation?

Purpose: Low-intensity pulsed ultrasound (LIPUS) has been used to stimulate the healing of the fresh fracture, delayed union, and non-union in both animal and clinical studies. Besides, biphasic calcium phosphate ceramic (BCP) is a promising biomaterial for bone repair as it shows favorable biocompatibility, osteoinduction, and osteoconduction. However, scarcity is known about the combined effect of LIPUS and BCP on bone formation. Methods: The combined effect of LIPUS and BCP was studied in a beagle model. Twelve dogs were used. BCP granules without any additions were implanted into bilateral erector spinae muscles. One side is the BCP group, while the counterlateral side is LIPUS + BCP group. Histological and histomorphometric analyses, and quantitative real-time polymerase chain reaction were evaluated. Results: Compared with BCP alone, the LIPUS + BCP showed no advantages in early bone formation. Furthermore, the Notch signaling pathway-related mRNA has no significant difference between the two groups. Conclusions: The preliminary results showed that the BCP, which has intrinsic osteoinduction nature, was an effective and promising material. However, LIPUS has no enhanced effect in BCP induced ectopic bone formation. Furthermore, LIPUS has no effect on the Notch signaling pathway. Whether costly LIPUS could be used in combination with BCP should be a rethink.

Prediction, analysis and application of learning curve of tooth preparation for all ceramic crowns of maxillary central incisors / 北京大学学报(医学版)

OBJECTIVE@#To predict the learning curve of tooth preparation for all ceramic crowns of maxillary central incisors on phantom head simulators for graduate students participating in standardized dental resident training based on the modified Wright learning curve model, then to analyze and applicate the learning curve.@*METHODS@#Twelve graduate students participating in standardized dental resident training were selected to prepare the resin maxillary central incisors on phantom head simulators for all ceramic crowns 4 times. The results of preparation were evaluated by 3 prosthetic experts with at least 10 years' experience focusing on the reduction, contour, taper, shoulder, finish line, margin placement, adjacent tooth injury, and preparation time for tooth preparation. The learning rate of tooth preparation was calculated by scores of tooth preparation of 4 times. The learning curve of tooth preparation was predicted based on the modified Wright learning curve model. According to the criteria of standardized training skill examinations for dental residents in Beijing, 80 was taken as the qualified standard score. The minimum training times for tooth preparation to satisfy the qualified standard score (80) was calculated, to analyze the characteristics of learning curve and evaluate the effectiveness of tooth preparation.@*RESULTS@#The scores of 4 tooth preparation were 64.03±7.80, 71.40±6.13, 74.33±5.96, and 75.98±4.52, respectively. The learning rate was (106±4)%, which showed the learning curve an upward trend. There were no significant differences between the qualified standard score and the predicted scores of tooth preparation from the 5th preparation to the 13th preparation (P > 0.05). The predicted score of the 14th preparation was higher than the qualified standard score (P < 0.05).@*CONCLUSION@#The trend of the learning curve of tooth preparation for all ceramic crowns of maxillary central incisors on phantom head simulators for graduate students participating in standardized dental resident training is upward, which predicts the minimum training times higher than the qualified standard score is 14 times.

Research on friction and wear behaviors of silicon-lithium spray coating on zirconia ceramics / 北京大学学报(医学版)

OBJECTIVE@#To study microstructure, friction and wear behaviors of silicon-lithium spray coating on the surface of zirconia ceramics and to preliminarily evaluate its esthetic so as to provide support and guidance for the clinical application.@*METHODS@#Zirconia ceramic specimens were randomly divided into three groups: coating group (two subgroups), polishing group (two subgroups), and glazing group (four subgroups), with 10 samples in each subgroup. The two subgroups of coating group were the zirconia ceramics with the untreated and preliminary polishing surfaces sprayed with silicon-lithium coating, respectively. The two subgroups of polishing group were preliminary polishing and fine polishing of zirconia ceramics, respectively. The four subgroups of glazing group were preliminarily polished zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively; and untreated zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively. The above 8 subgroups of zirconia ceramic specimens were used as friction pairs with 80 steatite ceramics for 50 000 chewing cycles under 50 N vertical load and artificial saliva lubrication using chewing simulation. Scanning electron microscope was used to observe the microstructure of the surface and section of the coating group, and the thickness of the coating and glazing were measured. The linear roughness of the coating and polishing groups was mea-sured using a laser confocal scanning microscope. Vickers hardness was measured using a microhardness tester and the esthetic of zirconia ceramic full crown sprayed with silicon-lithium coating was preliminarily evaluated. White light interferometer was used to measure the width, the maximum depth and the volume of the wear scars of each group, and the wear depth of steatite ceramics and wear rate of zirconia ceramic specimens were calculated. Kruskal-Wallis nonparametric test and Dunn's multiple comparisons test were used to analyze the wear depth of each group (α=0.05).@*RESULTS@#The microstructures of the silica-lithium spray coatings on the untreated and preliminarily polished zirconia ceramic surfaces showed the protruding defects, and the line roughness of coating group was larger than that of the polishing group. The median thickness of the silica-lithium spray coating on the preliminarily polished zirconia ceramic was 13.0 μm (interquartile range, IQR: 11.6, 17.9), while that of the silica-lithium spray coating on the untreated zirconia ceramic was 4.4 μm (IQR: 4.1, 4.7). The Vickers hardness and wear rate of the coating group were between the polishing group and the glazing group. The wear depths of the wear scars of steatite ceramics were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference between glazing and polishing groups (P < 0.05). With the increase of polishing procedure, the wear depth of steatite ceramics decreased in each subgroups. The orders of maximum depth and volume of wear scars of zirconia ceramic were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference in the maximum depth of wear scars between glazing and polishing groups (P < 0.05).@*CONCLUSION@#The silica-lithium spray coating on the zirconia ceramic, can be used as a new method for zirconia ceramic surface treatment, because it can increase the esthetic of zirconia ceramics compared with polishing and reduce the wear of steatite ceramics compared with glazing.

Meta-analysis of different joint interfaces in total hip arthroplasty under long-term follow-up / 中国骨伤

OBJECTIVE@#To compare the long-term follow-up effect and complications of ceramic on ceramic (CoC) interface and ceramic on polyethyleneon ceramic (CoP) interface in primary total hip arthroplasty, and provide clinical evidence.@*METHODS@#Search PubMed, EMBase, the CoChrane Library databases, Web of science, Wanfang database, and CNKI from January 2000 to September 2021, screening and inclusion of randomized controlled trials (RCTs) comparing the long-term efficacy and complications of CoC interface and CoP interface in total hip arthroplasty. Literature screening, quality evaluation and data extraction were carried out according to the inclusion and exclusion criteria, using Review Manager 5.3 statistical software. The software was used to perform statistical analysis on joint function, revision, prosthesis fracture, abnormal joint noise, and prosthesis wear rate after CoC or CoP.@*RESULTS@#Seven RCTs studies were included, including 390 cases of hips with CoC artificial joints and 384 cases of hips with CoP artificial joints. The long-term joint function improvement of CoC and CoP artificial joints was similar and there was no significant differences, with an average difference was MD=0.63, 95%CI=(-1.81, 3.07), P=0.61. About the postoperative complications, CoC artificial joints have higher incidence rate of abnormal joint noise, with odds ratio (OR)=11.05, 95%CI=(2.04, 59.84), P=0.005. CoP artificial joints wear faster, with an average MD=-87.11, 95%CI=(-114.40, -59.82), P<0.000 1. There was no significant difference between the two groups in the replacement-related complications such as joint dislocation, prosthesis loosening, osteolysis, and the rate of prosthesis revision caused by various reasons.@*CONCLUSION@#The clinical function results and complications of CoC artificial joints are comparable to those of CoP artificial joints. Although CoP artificial joint prosthesis has a faster wear rate, it does not affect joint function and increase complications, and there is no abnormal joint noise. CoC is expensive and the long-term efficacy is equivalent to CoP. Clinicians should consider cost performance when choosing CoC.

Study on the correlation between ceramic and chronic obstructive pulmonary disease in Foshan City / 中华劳动卫生职业病杂志

Objective: To study the correlation between ceramic and chronic obstructive pulmonary disease (COPD), and explore its related risk factors. Methods: In January 2021, five representative ceramic enterprises were selected from Chancheng District, Nanhai District, Gaoming District and Sanshui District of Foshan City. The ceramic workers who came to Chancheng Hospital of Foshan First People's Hospital for physical examination from January to October 2021 were selected as the research objects, and 525 people were included. Conduct questionnaire survey and pulmonary function test. Logistic regresion was performed to analyze the influencing facters of COPD among ceramic workers. Results: The subjects were (38.51±1.25) years old, 328 males and 197 females, and the detection rate of COPD was 9.52% (50/525). The incidence of respiratory symptoms such as dyspnea, chronic cough, wheezing and chest tightness, the detection rates of abnormal lung age, abnormal lung function and COPD in males were higher than those in females (P<0.05). The logistic regression analysis showed that male, age, working years, smoking status and family history of COPD were the risk factors for COPD among ceramic workers (P<0.05) . Conclusion: The ceramic workers are the high risk population of COPD. We should do a good job in health education, and do a regular physical examination to find the changes of lung function in time, and prevent the occurrence of COPD as soon as possible.

Design of a New Type of Electrochemical Ceramic Membrane Oxygen Production System / 中国医疗器械杂志

OBJECTIVE@#In order to solve the problem that the existing oxygen production technology cannot simultaneously produce pure oxygen, high-purity oxygen, ultra-pure oxygen, and the modular expansion of oxygen production capacity, a new type of electrochemical ceramic membrane oxygen production system was discussed and developed.@*METHODS@#Through the design of the ceramic membrane stack, airflow distributor, heater, double spiral exchanger, thermal insulation sleeve, control panel, control box and auxiliary system in the electrochemical ceramic membrane oxygen generator, a modular oxygen production system is formed.@*RESULTS@#The modular design can produce pure oxygen, high-purity oxygen and ultra-pure oxygen to meet various oxygen consumption needs.@*CONCLUSIONS@#The electrochemical ceramic membrane oxygen production system is a new type of oxygen production technology. The main components have no moving parts, no noise, and no pollution. It can produce pure oxygen, high-purity oxygen and ultra-pure oxygen on site, with small size, light weight, and module combination which is suitable for convenient expansion and installation of oxygen consumption.

Influence of restorative materials on occlusal and internal adaptation of CAD-CAM inlays

Aim: To evaluate the occlusal and internal marginal adaptation of inlay restorations made of different materials, using CAD-CAM. Methods: Preparations were made for MOD inlays of one-third intercuspal width and 4 mm depth in 30 third human molars. The teeth were restored using CAD-CAM materials (n=10) of nanoceramic resin (Lava Ultimate), polymer-infiltrated ceramic network (VITA ENAMIC), or lithium disilicate glass-ceramic (IPS e.max CAD). The specimens were cemented with dual resin cement and sectioned at the center of the restoration, after which the two halves were evaluated, and photographed The occlusal and internal discrepancy (µm) was determined at five points: cavosurface angle of the occlusal-facial wall (CA-O); center of the facial wall (FW); faciopulpal angle (FPA); center of the pulpal wall (PW); and center of the lingual wall (LW). The data were submitted to the Kruskal-Wallis and the Dunn tests (α=0.05). Results: No difference was observed among the materials regarding the occlusal discrepancy at the CA-O, FPA, or PW internal points. The e.max CAD measurement at FW showed larger internal discrepancy than that of Lava (p=0.02). The internal discrepancy at LW was greater for e.max CAD than VITA ENAMIC (p=0.02). Conclusion: Lithium disilicate glass-ceramic presented greater internal discrepancy in relation to the surrounding walls of the inlay preparations

The efficiency of ErCr: YSGG laser on the debonding of different thicknesses of ceramic veneers

Aims: To verify the efficacy of Er,Cr:YSGG laser for debonding of lithium disilicate (LD) reinforced glass ceramic veneers of different thicknesses. Methods: Forty bovine teeth were prepared and randomly divided into four groups (n=10/group) according to the ceramic disc thickness: C0.5 (Control group) and L0.5 (Laser irradiated group) in which LD discs had a thickness of 0.5mm and 5mm diameter; C1 and L1 in which LD discs had a thickness of 1mm and 5mm diameter. The lithium disilcate discs (IPS E.max®, shade HTA2) were fabricated following the manufacturer's recommendations and cemented to the prepared tooth surface. The Er,Cr:YSGG laser was applied to the laser groups at 2.5W and 25Hz for 60seconds. Universal testing machine was used to evaluate the shear bond strength for all samples at a cross head speed of 1mm/min in an inciso-gingival direction parallel to the sample surface. After debonding, the samples were examined under stereoscope to evaluate the mode of failure according to the adhesive remnant index (ARI). Results: Laser irradiation significantly diminishes the shear bond strength from 10.868 MPa to 3.778 MPa for C0.5 and L0.5 groups respectively (p=0.00) and from 14.711 MPa to 4.992 MPa for C1 and L1 groups respectively (p=0.00). The shear bond strength required for debonding increased with increasing thickness of discs, but without significant difference (p=0.110). Higher ARI scores were seen in the laser groups (more cement remaining adhered to the tooth) when compared to the control groups. Conclusions: The Er,Cr:YSGG laser could be an effective and useful tool in debonding of lithium disilicate ceramic veneers as it decreases the shear bond strength required for veneer debonding

Color and translucency stability of CAD/CAM restorative materials

Aim: This study assessed the color and translucency stability of a polymer infiltrated ceramic network (PICN) and compared it with a resin composite (RC) and a feldspathic ceramic (FEL). Methods: Disc-shaped samples of a PICN (Vita Enamic), a feldspathic ceramic (Vitablocks Mark II), and a resin composite (Brava block) were prepared from CAD/CAM blocks. PICN and RC surfaces were finished with a sequence of polishing discs and diamond paste. FEL samples received a glaze layer. The samples were subjected to 30-min immersions in red wine twice a day for 30 days. CIEL*a*b* coordinates were assessed with a spectrophotometer at baseline and after 15 and 30 days of immersion. Color alteration (ΔE00) and translucency parameter (TP00) were calculated with CIEDE2000. Average roughness was measured before the staining procedures. Color difference and translucency data were analyzed with repeated-measures ANOVA and Tukey's tests. Roughness was analyzed with the Kruskal-Wallis test. Results: Roughness was similar among the experimental groups. All materials had their color alteration significantly increased from 15 to 30 days of staining. PICN reached an intermediate ΔE00 between FEL and RC at 15 days. PICN revealed a color alteration as high as the composite after 30 days. No statistical difference was observed regarding translucency. Conclusion: PICN was not as color stable as the feldspathic ceramic at the end of the study. Its color alteration was comparable to the resin composite when exposed to red wine. However, the translucency of the tested materials was stable throughout the 30-day staining

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

Influência do Percentual de Ítrio nas Propriedades da Zircônia Monolítica: Revisão de Literatura / INFLUENCE OF YTRIO PERCENTAGE ON MONOLITHIC ZIRCONIA PROPERTIES: LITERATURE REVIEW

A principal desvantagem da zircônia convencional é sua alta opacidade. Dependendo de diversas condições, especialmente o conteúdo do estabilizador ítrio, é possível contornar essa questão. Em vista disso, várias gerações de zircônia estabilizada com ítrio foram desenvolvidas buscando aliar a robustez da zircônia com a estética das facetas em porcelana. O presente trabalho teve como objetivo realizar uma análise a respeito de como o aumento ou a redução do percentual de ítrio na composição das zircônias monolíticas podem influenciar em suas propriedades, sobretudo no que tange à translucidez. Este estudo foi executado através de uma revisão nas bases de dados SciELO, PubMed e Google Scholar, com artigos publicados entre 2013 e 2021.Desse modo, concluiu-se que o maior teor de Y2O3 tendeu a aumentar a quantidade de fase cúbica isotrópica presente e reduzir a quantidade de fase tetragonal birrefringente no ZrO2, juntamente com uma minimização da dispersão de luz por fases secundárias, levando ao aumento da translucidez e resistência ao envelhecimento. À medida que o óxido de ítrio aumenta, os tamanhos dos grãos de zircônia tendem a aumentar também. A tenacidade e a resistência à fratura podem ser consideravelmente sacrificadas.

Cimentação adesiva de cerâmicas vítreas para CAD/CAM: efeito do tipo de sistema adesivo e do envelhecimento em longo prazo na resistência de união ao cimento resinoso / Adhesive cementation of glass ceramics for CAD/CAM: effect of the type of adhesive system and long-term aging on the bond strength to resin cement

O objetivo desta pesquisa foi avaliar o efeito do tipo de sistema adesivo e do envelhecimento na molhabilidade e resistência de união das cerâmicas vítreas ao cimento resinoso. Blocos de silicato de lítio (SL - Celtra Duo, Dentsply Sirona), feldspática (FD - Vita Mark II, VITA Zahnfabrik) e cerâmica infiltrada por polímero (PIC - Vita Enamic, VITA Zahnfabrik) foram seccionados (N=96, 10 x 12 x 2 mm), incluídos e divididos aleatoriamente em 24 grupos de acordo com os fatores: "Cerâmica" (SL, FD e PIC), "Adesivo" (CONT­sem adesivo; C2P­ adesivo convencional de 2 passos; C3P­adesivo convencional de 3 passos; UNV­adesivo universal) e "Envelhecimento" (SE-sem; CE­com). Após o condicionamento das cerâmicas (HF 5%), silanização e aplicação do sistema adesivo de acordo com o grupo experimental, cilindros (n=15, Ø = 2 mm e altura = 2 mm) de cimento resinoso (RelyX Ultimate, 3M ESPE) foram confeccionados (4 cilindros/bloco), sendo metade das amostras armazenadas em água destilada a 37°C por 24h (SE) e metade foi submetida à termociclagem 10.000 ciclos e armazenamento em água a 37°C por 18 meses (CE). Em seguida, as amostras foram submetidas ao teste de resistência de união ao cisalhamento (RUC - 100 KgF, 1 mm/min), análises de falhas, mensuração do ângulo de contato e análise da interface por meio da microscopia eletrônica de varredura (MEV). Os dados da RUC (MPa) e ângulo de contato foram analisados pelo ANOVA2 fatores e ANOVA-1 fator, respectivamente e Tukey (5%). A análise de Weibull foi realizada para a RUC. ANOVA-2 fatores revelou que o fator "Adesivo" foi significativo apenas para as cerâmicas SL (p<0,0001) e FD (p=0,0079). Já a interação Adesivo/Envelhecimento (p=0,0015) e "Envelhecimento" (p=0,0008) foram significativos apenas para SL. Para SL, após o envelhecimento os grupos CE_UNV (22,18± 7,74CD) e CE_C2P (17,32± 5,86D ) foram inferiores ao controle (30,30± 6,11A ). Apenas o grupo UNV apresentou redução significativa após envelhecimento. Para FD, C2P apresentou a menor RUC em relação aos demais grupos. PIC apresentou similaridade da RUC entre todos os grupos. O ângulo de contato de UNV apresentou o menor valor para SL (55,27°) e FD (51,34°). Para PIC, C3P apresentou o maior ângulo (63,00°) e CONT o menor (49,83°). Portanto, a aplicação de um adesivo não foi benéfica para a adesão da cerâmica ao cimento. Ademais, o uso de C2P e UNV após silanização da cerâmica SL e C2P para FD deve ser avaliada com precaução, já que a resistência de união foi reduzida em comparação ao grupo controle após o envelhecimento (AU).

The aim of this study was to evaluate the effect of the type of adhesive system and aging on the wettability and bond strength of glass ceramics to resin cement. Lithium silicate (SL - Celtra Duo, Dentsply Sirona), feldspathic (FD - Vita Mark II, VITA Zahnfabrik) and polymerinfiltrated ceramic (PIC - Vita Enamic, VITA Zahnfabrik) blocks were sectioned (N=96, 10 x 12 x 2 mm), included and randomly divided into 24 groups according to the factors: "Ceramics" (SL, FD and PIC), "Adhesive" (CONT­without adhesive; C2P­conventional 2-step adhesive; C3P­adhesive conventional 3-step; UNV­universal adhesive) and "Aging" (SE-non-aged; CEaged). After the conditioning of the ceramics (HF 5%), silanization and application of the adhesive system according to the experimental group, cylinders (n=15, Ø = 2 mm and height = 2 mm) of resin cement (RelyX Ultimate, 3M ESPE) were made (4 cylinders/block) and half of the samples were stored in distilled water at 37°C for 24h (SE) and half were subjected to thermocycling 10,000 cycles and storage in water at 37°C for 18 months (EC). Then, the samples were submitted to the shear bond strength test (RUC - 100 KgF, 1 mm/min), failure analysis, contact angle measurement and interface analysis by means of scanning electron microscopy (SEM). RUC (MPa) and contact angle data were analyzed by ANOVA 2-way and ANOVA 1-way, respectively, and Tukey (5%). Weibull analysis was performed for RUC. ANOVA 2-way revealed that the "Adhesive" factor was significant only for SL (p<0.0001) and FD (p=0.0079) ceramics. The Adhesive/Aging interaction (p=0.0015) and "Aging" (p=0.0008) were significant only for SL. For SL, after aging, the CE_UNV (22.18± 7.74CD) and CE_C2P (17.32± 5.86D) groups were lower than the control (30.30± 6.11A). Only the UNV group showed a significant decrease after aging. For FD, C2P had the lowest RUC in relation to the other groups. PIC showed similarity of RUC between all groups. The UNV contact angle presented the lowest value for SL (55.27°) and FD (51.34°). For PIC, C3P presented the highest angle (63.00°) and CONT the smallest (49.83°). Therefore, the application of an adhesive was not beneficial for the adhesion of the ceramic to the resin cement. Furthermore, the use of C2P and UNV after silanization of SL and C2P ceramics for FD should be evaluated with caution, as the bond strength was reduced compared to the control group after aging (AU).

Restabelecimento estético de incisivos laterais conóides e amplas restaurações em resina composta com laminados cerâmicos: relato de caso / Aesthetic recovering of conoid side incisives and wide restoration in composed resin with ceramic laminates: case report

Introdução: As cerâmicas odontológicas são amplamente utilizadas na Odontologia, desfrutando de grande popularidade devido a sua capacidade de mimetizar as características ópticas do esmalte e da dentina. O constante desenvolvimento de pesquisas tem desencadeado o lançamento de novos sistemas cerâmicos com propriedades aprimoradas e melhores resultados clínicos em longo prazo. Objetivo: O relato de caso aqui apresentado descreve uma reabilitação da zona estética do sorriso com laminados cerâmicos por meio de uma abordagem minimamente invasiva. Relato de caso: Paciente do gênero feminino, compareceu à clínica odontológica relatando insatisfação com a aparência do seu sorriso. Durante avaliação foram observadas, na região anterossuperior, restaurações extensas em resina composta deficientes nos incisivos, com proporção, volume, forma e texturização insatisfatórias, que em conjunto comprometia a zona estética do sorriso. Diante disso, após fotografias extra e intraorais, o tratamento proposto foi a reabilitação com laminados cerâmicos nas unidades 1.2 ao 2.2. Assim, foi realizado o enceramento e o mock-up, os quais serviram de orientação para os preparos dentários, a seguir, foram moldados e as restaurações confeccionadas no sistema IPS e.max. Após prova de cor e adaptação, os preparos e a superfície interna dos laminados cerâmicos foram tratados e cimentados com cimento resino fotopolimerizável. Conclusão: Instituindo uma abordagem conservadora, o plano de tratamento realizado através da reabilitação com laminados cerâmicos nas unidades dentárias anterossuperiores, permitiu o restabelecimento da função e estética, com reprodução das características dos dentes naturais e promoção do equilíbrio, da jovialidade e da harmonia no sorriso(AU)

Introduction: Dental ceramics are widely used in dentistry, enjoying great popularity due to the ability to mimic both enamel and dentin optical characteristics. The constant research development has triggered the launch of new ceramic systems with improved properties and better long-term clinical results. Objective: The case report presented here describes the zone rehabilitation of the aesthetic smile with ceramic laminates through a minimally invasive approach. Case report: Female patient, attended the dental clinic reporting dissatisfaction with the appearance of her smile. During the evaluation, extensive restorations in composite resin were observed in the incisors in the anterosuperior region, with unsatisfactory proportion, amount, shape and texturing, which together compromised the aesthetic zone of the smile. Faced with this, after extra and intraoral photographs, the proposed treatment was the restoration with the ceramic laminates in units 1.2 to 2.2. Thus, waxing and mock-up were performed, which served as guidance for the dental preparations, then they were molded and restorations fabricated in the IPS e.max system. After shade and adaptation proof, the preparations and the inner ceramic laminates surface were treated and cemented with light-cured resin cement. Conclusion: Adopting a conservative approach, the treatment plan carried out through restoration with ceramic laminates on the upper anterior teeth allowed the recovering function and aesthetics, reproducing characteristics of natural teeth and promoting balance, joviality and harmony in the smile(AU)