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).

Which Zirconia Surface-cleaning Strategy Improves Adhesion of Resin Composite Cement after Saliva Contamination? A Systematic Review and Meta-Analysis.

PURPOSE: To identify the most effective cleaning method for saliva-contaminated zirconia surface before adhesive cementation through a systematic review and meta-analysis. MATERIALS AND METHODS: PubMed, Scopus, and Web of Science databases were searched to select in vitro studies published through October 2021. Studies that did not perform aging methods, had a sample size less than 5 per group, or did not present a group with zirconia contaminated only with saliva were excluded. Data were extracted and risk of bias was assessed. Statistical analysis comparing the cleaning methods was conducted, and the standardized mean difference was assessed using the R software program. RESULTS: Among 804 potentially eligible studies, 36 were selected for full-text reading, of which 13 were included in qualitative analysis, and 11 of these were subsequently included in the quantitative analysis. A meta-analysis revealed a significant difference in the bond strength between the cleaning methods. Sandblasting with Al2O3  showed a higher bond strength than cleaning solution (Ivoclean, Ivoclar Vivadent) (p < 0.01, I2 = 65%), and both methods promoted higher resin-bond strength to zirconia than water cleaning. In addition, there was no significant difference in the bond strength between alcohol (p = 0.35, I2 = 79%), phosphoric acid (p < 0.23, I2 = 90%), and water cleaning. CONCLUSION: Sandblasting with Al2O3 seems to be the best method for zirconia surface cleaning before adhesive luting, promoting better resin-bond strength to zirconia.

Restabelecimento da Dimensão Vertical de Oclusão com JIG estético modificado e Prótese Parcial Removível Overlay: relato de caso / Reestablishment of occlusal vertical dimension with a modified aesthetic JIG and an overlay removable partial denture: a case report

A reabilitação de pacientes parcialmente edêntulos com desgaste dentário severo e dimensão vertical de oclusão reduzida é desafiadora e complexa. Objetivo: Descrever o restabelecimento da dimensão vertical de oclusão e parâmetros estéticos com uma prótese parcial removível do tipo overlay (PPRO) com auxílio de um JIG estético modificado. Relato de caso: Paciente do sexo masculino, 58 anos de idade, procurou serviço odontológico queixando-se de insatisfação com a estética do sorriso e perda dos dentes posteriores. Ao exame clínico, foram observados desgaste dentário excessivo e edentulismo parcial nas arcadas superior e inferior. Então, foi proposto tratamento em 2 etapas (provisória e definitiva) com PPRO em maxila. O JIG estético foi usado como guia de referência para incrementos em resina composta fotopolimerizável e o restabelecimento da dimensão vertical de oclusão foi determinado a partir de métodos métrico, fonético e estético. Os dentes desgastados foram aumentados e os dentes ausentes substituídos por dentes artificiais a partir de uma PPRO provisória. Após 2 meses de adaptação, a reabilitação final com PPRO definitiva foi conduzida baseando-se na reabilitação com a PPRO provisória. Conclusão: O paciente relatou satisfação com a estética e desempenho funcional com o tratamento. Portanto, o JIG estético beneficia o planejamento e o tratamento para restabelecer a dimensão vertical de oclusão. Além disso, a PPRO é uma alternativa reversível, de baixo custo, para reabilitar a estética e a função de pacientes com desgaste severo e perda parcial dos dentes.

The rehabilitation of partially edentulous patients with severe tooth wear and reduced occlusal vertical dimension is challenging and complex. Objective: To describe the reestablishment of occlusal vertical dimension and aesthetic parameters with an overlay re-movable partial denture (ORPD) with the aid of a modified aesthetic JIG. Case report: A 58-year-old man sought dental service complaining of dissatisfaction with the aesthetics of his smile and a loss of posterior teeth. At clinical examination, excessive tooth wear and partially edentulism in the lower and upper arches were observed. A two-step treatment (interim and definitive) with an ORPD in the upper arch was proposed. The aesthetic JIG was used as a reference guide for the increments in light-curing resin composite, and the reestablishmentthe occlusal vertical dimension was determined using aesthetic, phonetic, and metric methods. The worn teeth were increased, and the missing natural teeth were replaced by artificial teeth using a temporary ORPD. After two months of adaptation, de-finitive rehabilitation with a definitive ORPD was performed based on the interim ORPD. Conclusion: The patient reported satisfaction with the esthetic and functional performance of this treatment. Therefore, the aesthetic JIG benefits the planning and treatment of reduced vertical dimension. Moreover, the ORPD is a reversible and lower-cost alternative to rehabilitate the aesthetics and function of patients with severe teeth wear and partial teeth loss.

CAD-FEA modeling and fracture resistance of bilayer zirconia crowns manufactured by the rapid layer technology.

In the RLT (Rapid Layer Technology), veneering ceramic and framework are fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) and then cemented to obtain the restoration. This study aimed to evaluate the effect of the thickness of veneering ceramic manufactured by the RLT technique on the fracture resistance (FR) of bilayer crowns with zirconia frameworks. Twenty zirconia frameworks and twenty feldspathic posterior crowns with two different veneering ceramic occlusal thicknesses (1mm=TF1; 2mm=TF2) were manufactured using CAD/CAM system. The specimens were luted to an epoxy resin abutment with resin cement and mechanically cycled (200N and 4.5×105 Pa, 37°C, 2×106 cycles, 3Hz). The FR test was performed (10kN, 0.5mm/min), and the specimens were analyzed in a stereomicroscope. For the stress analysis (finite element analysis, FEA), a 10kN load was equal to the in vitro test, and the principal stress was evaluated. The FR data were analyzed by Student's t-test and Weibull's analysis. The thickness influenced the FR of bilayer crowns. The FR was higher in the TF2 than in the TF1 group. The TF2 group presented the highest characteristic strength compared to the group TF1. The predominant type of failure was delamination. The FEA showed higher stress concentrations below the loading application point at the veneering cement interface in the 1-mm-thick model. The bilayer crowns manufactured using the approach of 2mm of veneering ceramic promoted higher FR compared to the group with 1mm veneering ceramic. Also, the FEA showed that the veneer ceramic thickness has an effect on stress distribution in zirconia-based bilayer crowns.

CAD-FEA modeling and fracture resistance of bilayer zirconia crowns manufactured by the rapid layer technology

Abstract In the RLT (Rapid Layer Technology), veneering ceramic and framework are fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) and then cemented to obtain the restoration. This study aimed to evaluate the effect of the thickness of veneering ceramic manufactured by the RLT technique on the fracture resistance (FR) of bilayer crowns with zirconia frameworks. Twenty zirconia frameworks and twenty feldspathic posterior crowns with two different veneering ceramic occlusal thicknesses (1mm=TF1; 2mm=TF2) were manufactured using CAD/CAM system. The specimens were luted to an epoxy resin abutment with resin cement and mechanically cycled (200N and 4.5×105 Pa, 37°C, 2×106 cycles, 3Hz). The FR test was performed (10kN, 0.5mm/min), and the specimens were analyzed in a stereomicroscope. For the stress analysis (finite element analysis, FEA), a 10kN load was equal to the in vitro test, and the principal stress was evaluated. The FR data were analyzed by Student's t-test and Weibull's analysis. The thickness influenced the FR of bilayer crowns. The FR was higher in the TF2 than in the TF1 group. The TF2 group presented the highest characteristic strength compared to the group TF1. The predominant type of failure was delamination. The FEA showed higher stress concentrations below the loading application point at the veneering cement interface in the 1-mm-thick model. The bilayer crowns manufactured using the approach of 2mm of veneering ceramic promoted higher FR compared to the group with 1mm veneering ceramic. Also, the FEA showed that the veneer ceramic thickness has an effect on stress distribution in zirconia-based bilayer crowns.

Resumo Na RLT (Rapid Layer Technology), a cerâmica de cobertura e infraestrutura são fabricados pelo Computer-Aided Design / Computer-Aided Manufacturing (CAD / CAM) e cimentados para obter a restauração. Este estudo teve como objetivo avaliar o efeito da espessura da cerâmica de cobertura fabricada pela técnica RLT na resistência à fratura (RF) de coroas bilaminadas com infraestrutura de zircônia. Vinte infraestruturas de zircônia e vinte coroas posteriores feldspáticas com duas espessuras oclusais da cerâmica de cobertura (1mm = TF1; 2mm = TF2) foram fabricadas usando o sistema CAD / CAM. Os espécimes foram cimentados em preparos de resina epóxi com cimento resinoso dual e ciclados mecanicamente (200N e 4,5×105 Pa, 37° C, 2×106 ciclos, 3Hz). O teste de RF foi realizado (10kN, 0,5mm / min) e, posteriormente, os espécimes foram analisados em estereomicroscópio. Para a análise de tensão (análise de elementos finitos, FEA), uma carga de 10kN foi aplicada igual ao teste in vitro, e a tensão principal foi avaliada. Os dados de RF foram analisados pelo teste t de Student e análise de Weibull. A espessura mostrou forte influência na RF das coroas bilaminadas. A RF foi maior em TF2 do que no grupo TF1. O grupo TF2 apresentou a maior resistência característica em relação ao grupo TF1. O tipo de falha predominante foi a delaminação. O FEA mostrou maiores concentrações de tensões abaixo do ponto de aplicação da carga, na interface cimento e cerâmica de cobertura no modelo de coroa de 1 mm de espessura. As coroas de bilaminadas confeccionadas com 2 mm de cerâmica de cobertura promoveram maior RF em comparação ao grupo com cerâmica de cobertura de 1 mm. Além disso, a FEA mostrou que a espessura da cerâmica de cobertura tem um efeito na distribuição de tensões em coroas bilaminadas à base de zircônia.

Effect of different surface treatments on the biaxial flexure strength, Weibull characteristics, roughness, and surface topography of bonded CAD/CAM silica-based ceramics.

OBJECTIVE: To investigate the influence of different surface treatments on biaxial flexure strength, roughness, and surface topography of lithium silicate/disilicate-based ceramics. METHODS: 225 discs (∅: 12 mm; 1.2 mm - ISO 6872) were made from three ceramics: IPS e.max CAD (LD - Ivoclar Vivadent), Suprinity (LSS - Vita) and Celtra Duo (LSC - Dentsply). The samples were randomly divided into 5 groups (n = 15): no treatment (C); 10% hydrofluoric acid + silane (HF); sandblasting Al2O3 + silane (SB); silicatization + silane (SC); and self-etching ceramic primer (SEP). After surface treatment, a resin cement layer was applied to the disc surface (RelyX U200, 3M ESPE), mechanical cycled (1.2 × 106 cycles, 50 N, 3.8 Hz) and submitted to biaxial flexural strength test (1 mm/min, 1000 Kgf). Roughness, EDS and SEM were also performed. Data were analyzed by one-way ANOVA, Tukey test (5%) and Weibull. RESULTS: ANOVA revealed that the "surface treatment" factor was significant for all ceramics (p < 0.05). The groups LD-HF (289.30 ± 40) LD-SEP (298. 87 ± 53.29), LSC-HF (195.51 ± 42.12), LSS-HF (269.58 ± 27.07) and LSS-SEP (207.45 ± 28.63) presented significantly higher biaxial flexure strength than respective control groups, except for the LSC-SEP (165.41 ± 33.86), which was statistically similar to the control. The Weibull modulus was significantly higher for the LD-SB, LSC-SC groups. Additionally, the LD-SB, LSC-SC and LSS-HF groups showed higher roughness compared to the other treatments. SIGNIFICANCE: HF etching followed by silanization and self-etching ceramic primer are the most suitable surface treatments for lithium silicate/disilicate-based glass-ceramics.

Effect of glazing application side and mechanical cycling on the biaxial flexural strength and Weibull characteristics of a Y-TZP ceramic.

OBJECTIVE: Glaze application on monolithic zirconia (Y-TZP) can be a practical approach to improve the mechanical properties of this material. Our study evaluated the effect of glazing side and mechanical cycling on the biaxial flexure strength (BFS) of a Y-TZP. METHODOLOGY: Eighty sintered Y-TZP discs (Ø:12 mm; thickness: 1.2 mm - ISO 6872) were produced and randomly assigned into eight groups (n=10), according to the factors "glazing side" (control - no glazing; GT - glaze on tensile side; GC - glaze on compression side; GTC - glaze on both sides) and "mechanical aging" (non-aged and aged, A - mechanical cycling: 1.2×106, 84 N, 3 Hz, under water at 37°C). Specimens were subjected to BFS test (1 mm/min; 1,000 Kgf load cell) and fractured surfaces were analyzed by stereomicroscopy and SEM. Hsueh's rigorous solutions were used to estimate the stress at failure of glazed specimens. Two-way ANOVA, Tukey's test (5%), and Weibull analysis were performed. RESULTS: The "glazing side", "mechanical aging" and the interaction of the factors were significant (p<0.05). Groups GC (1157.9±146.9 MPa), GT (1156.1±195.3 MPa), GTC (986.0±187.4 MPa) and GTC-A (1131.9±128.9 MPa) presented higher BFS than control groups (Tukey, 5%). Hsueh's rigorous solutions showed that the maximum tensile stress was presented in the bottom of zirconia layer, at the zirconia/glaze interface. Weibull characteristic strength (σo) of the GC was higher than all groups (p<0.05), except to GT, GTC-A and GTC, which were similar among them. The fractography showed initiation of failures from zirconia the tensile side regardless of the side of glaze application and fatigue. CONCLUSION: Glazing zirconia applied on both tensile and compression sides improves the flexural strength of Y-TZP, regardless the mechanical aging.

Effect of glazing application side and mechanical cycling on the biaxial flexural strength and Weibull characteristics of a Y-TZP ceramic

Abstract Glaze application on monolithic zirconia (Y-TZP) can be a practical approach to improve the mechanical properties of this material. Objective Our study evaluated the effect of glazing side and mechanical cycling on the biaxial flexure strength (BFS) of a Y-TZP. Methodology Eighty sintered Y-TZP discs (Ø:12 mm; thickness: 1.2 mm - ISO 6872) were produced and randomly assigned into eight groups (n=10), according to the factors "glazing side" (control - no glazing; GT - glaze on tensile side; GC - glaze on compression side; GTC - glaze on both sides) and "mechanical aging" (non-aged and aged, A - mechanical cycling: 1.2×106, 84 N, 3 Hz, under water at 37°C). Specimens were subjected to BFS test (1 mm/min; 1,000 Kgf load cell) and fractured surfaces were analyzed by stereomicroscopy and SEM. Hsueh's rigorous solutions were used to estimate the stress at failure of glazed specimens. Two-way ANOVA, Tukey's test (5%), and Weibull analysis were performed. Results The "glazing side", "mechanical aging" and the interaction of the factors were significant (p<0.05). Groups GC (1157.9±146.9 MPa), GT (1156.1±195.3 MPa), GTC (986.0±187.4 MPa) and GTC-A (1131.9±128.9 MPa) presented higher BFS than control groups (Tukey, 5%). Hsueh's rigorous solutions showed that the maximum tensile stress was presented in the bottom of zirconia layer, at the zirconia/glaze interface. Weibull characteristic strength (σo) of the GC was higher than all groups (p<0.05), except to GT, GTC-A and GTC, which were similar among them. The fractography showed initiation of failures from zirconia the tensile side regardless of the side of glaze application and fatigue. Conclusion Glazing zirconia applied on both tensile and compression sides improves the flexural strength of Y-TZP, regardless the mechanical aging.

"Se parar, parou": categorização do morrer em uma unidade de terapia intensiva da cidade do Rio de Janeiro / "When it's over, it's over": the characterization of death in an intensive care unit in Rio de Janeiro

A unidade de terapia intensiva foi criada para atender enfermos muito graves, com risco de vida. Para tanto, conta com assistência médica e de enfermagem ininterruptas, com equipamentos específicos, recursos humanos especializados e acesso a aparelhagem sofisticada, destinada a diagnóstico e terapêutica, para manutenção da vida. Este artigo apresenta uma reflexão em torno das possibilidades de processos do morrer em uma unidade de tratamento intensivo, com base em pesquisa etnográfica em hospital público universitário da cidade do Rio de Janeiro. Apesar do contato frequente com o processo do morrer, em certas situações, alguns intensivistas demonstram tensão e/ou dificuldade na aceitação da morte, especialmente em situações de "morte inesperada". Neste tipo de situação, alguns profissionais expressam sentimentos, especialmente aqueles com mais tempo de contato com o doente. Já na "morte esperada", os profissionais esperam que ela ocorra e, assim há menor mobilização de sentimentos. Como a rotina da unidade não deve ser perturbada, estratégias são construídas e acionadas para lidar com essas situações. O estudo evidenciou o recurso ao humor, quando eufemismos e brincadeiras emergem, para aliviar a tensão que porventura se instale no ambiente da unidade de terapia intensiva, setor em que a morte é uma presença cotidiana.

The intensive care unit was created to care for seriously ill patients who are at risk of death. For this purpose, it provides uninterrupted medical and nursing care, with specialized human resources and access to sophisticated diagnosis and therapy equipment in order to maintain life. This article presents a reflection around the different possibilities for the dying process in an intensive care unit, based on ethnographic research at a university public hospital in the city of Rio de Janeiro. Despite having frequent contact with the dying process, in certain situations some intensivists demonstrated tension and/or difficulty accepting death, especially in cases of "sudden death". In this type of situation, some professionals expressed feelings, especially those who had been in contact with the patient for a longer period of time. As for "expected death" situations, professionals are expecting the event and are thus less affected by feelings. Since the unit's routine must not be disrupted, strategies are constructed and activated to deal with these situations. This study revealed the use of humor, including euphemisms and jokes, to relieve any tension that may establish itself in the intensive care unit environment, where death is an everyday occurrence.