Effect of Surface-Etching Treatment, Glaze, and the Antagonist on Roughness of a Hybrid Ceramic after Two-Body Wear.

Stains and glaze are effective procedures for achieving an aesthetic smoothness on indirect restorations. Thus, the effect of surface-etching treatments previous to the stain layer and the glaze application on the occlusal and antagonist wear of a hybrid ceramic were evaluated against different antagonists. Disc-shaped samples were prepared from polymer-infiltrated ceramic network (PICN) blocks. The specimens were divided into eight groups, according to the surface-etching treatment and glaze application: P (polished specimens); PG (polishing plus glaze); E (hydrofluoric acid etching plus stain); EG (acid etching plus stain plus glaze); A (aluminum oxide sandblasting plus stain); AG (sandblasting plus stain plus glaze); S (self-etching primer plus stain); SG (self-etching primer plus stain plus glaze). Half of the samples were subjected to a wear simulation with a steatite antagonist, and the other half was tested using a PICN antagonist. The test parameters were: 15 N, 1.7 Hz, 6 mm of horizontal sliding, 5000 cycles. The discs and the antagonists' masses were measured before and after the wear tests. The average roughness and spacing defects were evaluated. The etching treatment affected the surface and antagonist mass loss when tested against steatite. AG showed the highest mass loss. This influence was not detected when using the PICN antagonist. The glaze application after staining ensures a smoother surface and avoids antagonist wear.

Interfacial Fracture Energy Between New Translucent Zirconias and a Resin Cement.

PURPOSE: To determine the interfacial fracture energy (IFE) and stress distribution of Brazil-nut-shaped specimens made of translucent zirconia and resin cement. MATERIALS AND METHODS: Three types of translucent zirconia were used: 3Y-TZP (high, Vita YZ HT), 4Y-TZP (super, Vita YZ ST), and 5Y-TZP (extra, Vita YZ XT). The adhesive surfaces were air abraded and 10-MDP-based resin cement was used. The cemented Brazil-nut-shaped specimens, with an elliptical defect in the center (as in real Brazil nuts), were thermally aged (5°C-55°C; 40,000 cycles). The IFE test was conducted with a piston to apply compression on the specimen, while the adhesive interface was positioned at four different angles (0, 10, 20, and 30 degrees) to measure the IFE during tensile, shear, and mixed failure modes. All adhesive interfaces were observed to determine failure patterns. The finite element analysis (FEA) was used to calculate tensile and shear stress distributions according to inclinations. Statistical analysis was conducted using the Kruskal-Wallis and Dunn's post-hoc tests (95%), as well as the Mann-Whitney test (95%) was applied to compare each group regarding the aging factor. RESULTS: According to Kruskal-Wallis and Dunn's post-hoc tests, there were no statistically significant differences between non-aged (p > 0.05) and aged materials (p > 0.05). However, there was a significant difference between aged and non-aged materials for all inclinations (p < 0.05) (Mann-Whitney test). According to the FEA, the compressive loading of Brazil-nut-shaped specimens at different angles showed a predominance of tensile stress at 0 degrees and shear stress at 30 degrees. CONCLUSION: The IFE under predominantly shear stresses is higher than when specimens are subjected only to tensile stresses, which allows the interpretation that failures in the oral environmental will probably occur preferentially under tensile stresses, because less energy is needed. All translucent zirconia bonded to resin cement has similar IFE, and thermal aging negatively affects these bonding interfaces.

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 surface treatment and glaze application on shade characterized resin-modified ceramic after toothbrushing.

STATEMENT OF PROBLEM: The extrinsic characterization with pigments and glaze application on the surface of ceramic restorations promotes individualization and esthetics. However, whether this characterization is resistant to toothbrushing abrasive wear is unclear. PURPOSE: The purpose of this in vitro study was to investigate the abrasive wear resistance of characterized and glazed resin-modified ceramic with different surface treatments before characterization. MATERIAL AND METHODS: Eighty rectangular specimens (10×8×6 mm) were precision cut from Vita Enamic and randomly divided in 4 groups as per the surface treatment before the characterization technique. These groups included the following: no additional treatment or polishing only, acid etching, airborne-particle abrasion, and self-etching silanization. For each surface treatment, 2 subgroups were created considering the presence or absence of the glaze layer after shade characterization, totaling 8 groups (n=10). The specimens were submitted to toothbrushing simulation (150 000 cycles, 2.45-N, 180 strokes per minute) with a soft and straight toothbrush and a solution of toothpaste and distilled water (250 g/L). After each 50 000 cycles, the wear of the characterized surface was measured by using a contact profilometer in µm which was equivalent to 5, 10, and 15 years of simulated toothbrushing. The rates were analyzed by using 3-way ANOVA and the post hoc Tukey test (α=.05). Scanning electron microscopy analysis was performed to access the surface profile between the evaluated periods. RESULTS: The mean wear rate (Rz) of the characterized surface was affected by the isolated factors, including surface treatment, glaze, and time (P<.001), with no interactive effects noted. A higher mean value of Rz was observed for polishing only (12.9 ±4.4 µm), followed by airborne-particle abrasion (10.2 ±4.5 µm), acid etching (9.4 ±2.4 µm), and then self-etching silanization (7.6 ±2.9 µm). Mean wear rate was also increased by the glaze (11.1 ±4.7 µm) compared with its absence (9 ±3.2 µm) and by the length of time, with 15 years (11.3 ±4.5 µm) followed by 10 years (9.8 ±4.0 µm) and 5 years (9 ±3.6 µm). The scanning electron microscopy images showed similar worn surfaces for each subgroup, glaze removal after 150 000 cycles, and surface homogeneity in function of time. CONCLUSIONS: Self-etching silanization was found to be the treatment suitable for reducing the wear of characterized resin-modified ceramic during prolonged brushing of more than 5 years. Glaze application did not protect the characterization from surface wear, regardless of the ceramic surface treatment performed on the specimens.

Novel speed sintered zirconia by microwave technology.

OBJECTIVE: Continuous efforts have been made to hasten the zirconia densification process without compromising properties. This study evaluated the long-term structural durability of microwave speed-sintered zirconia (MWZ) relative to a conventionally sintered zirconia (CZ). METHODS: As-machined dental 3Y-TZP discs (Ø12 × 1.2 mm) were speed sintered at 1450 °C for 15 min using an industrial microwave oven, while conventional sintering was conducted in a standard dental furnace at 1530 °C for 2 h. Both were followed by natural cooling. The total sintering time was 105 min for MWZ and 600 min for CZ. Groups were compared regarding density, grain size, phase composition, and fracture resistance. Structural durability was investigated employing two fatigue protocols, step-stress and dynamic fatigue. RESULTS: Compared to CZ, MWZ exhibited a slightly lower density (MWZ = 5.98 g/cm3, CZ = 6.03 g/cm3), but significantly smaller grain sizes (MWZ = 0.53 ± 0.09 µm, CZ = 0.89 ± 0.10 µm), lower cubic-zirconia contents (MWZ = 15.3%, CZ = 22.7%), and poorer translucency properties (TP) (MWZ = 13 ± 1, CZ = 29 ± 0.8). However, the two materials showed similar flexural strength (MWZ = 978 ± 112 MPa, CZ = 1044 ± 161 MPa). Additionally, step-stress testing failed to capture the fatigue effect in 3Y-TZP, whereas dynamic fatigue revealed structural degradation due to moisture-assisted slow-crack-growth (SCG). Finally, MWZ possessed a slightly higher Weibull modulus (MWZ = 7.9, CZ = 6.7) but similar resistance to SCG (MWZ = 27.5, CZ = 24.1) relative to CZ. SIGNIFICANCE: Dental 3Y-TZP with similar structural durability can be fabricated six-times faster by microwave than conventional sintering.

Minimal tooth preparation for posterior monolithic ceramic crowns: Effect on the mechanical behavior, reliability and translucency.

OBJECTIVE: Despite the increased use of monolithic crowns, their performance has yet to be determined when the minimal tooth preparation (MTP) principle is considered. The goal of this study was to evaluate the effect of MTP on the mechanical behavior, reliability and translucency of posterior monolithic ceramic crowns. METHODS: Dentin analogues were machined using two preparation designs (0.5 or 1 mm reduction) to receive first molar crowns in order to evaluate the monolithic crown performance. Next, 126 crowns were divided (21/g) according to the material (High translucent zirconia - YZHT, Zirconia reinforced lithium silicate - ZLS and Hybrid ceramic - HC) and thickness (0.5 or 1 mm). Tensile stress concentration was calculated using the finite element method. The crowns were adhesivelly cemented and step stress fatigued to calculate reliability for missions at 600 and 1000 N. Translucency was analyzed in 10 discs of each material and thickness. RESULTS: Higher stress concentration was found in thinner crowns and those with higher elastic modulus. YZHT crowns were suspended when fatigue reached 1500 N load, thus 1-parameter Weibull was used to analyze the data. Reliability was only affected by thickness at 1000 N. ZLS.5 showed lower survival than HC.5, which was similar to the groups that presented 100% survival. YZHT showed the highest strength and data scattering. ZLS1 (22.3 ± 1.4) presented higher translucency than HC1 (19.2 ± 0.6) and YZHT1 (12.0 ± 2.9), whereas ZLS.5 and HC.5 were similar to each other (26.5 ± 2.3, 26.7 ± 2.2) and superior to YZHT.5 (12.7 ± 1.2). SIGNIFICANCE: HC.5 combined high reliability and translucency with low stress concentration, yielding better crown performance and tooth preservation.

Long-term fracture load of all-ceramic crowns: Effects of veneering ceramic thickness, application techniques, and cooling protocol.

BACKGROUND: To evaluate, in vitro, the effects of the cooling protocol, application technique, and veneering ceramic thickness on the fracture resistance of ceramic crowns with Y-TZP frameworks. MATERIAL AND METHODS: 80 frameworks were made from zirconia by the CAD/CAM technique and divided into 8 groups (n = 10) according to the factors: "application technique" (stratified-L and pressed -P), "thickness" (1 mm and 2 mm), and "cooling protocol" (slow-S and fast-F) of the feldspathic veneering ceramic. After, all crowns were cemented over G10 preparations with resin cement (Panavia F, Kuraray), mechanically cycled (2x106 cycles, 200 N, 3Hz), and subjected to the axial compression resistance test (0.5 mm/min, 10 kN). The data (N) underwent descriptive statistical analysis by 3-way ANOVA and Tukey's test (5%). Fracture analysis was performed to determine the possible origin of failure. RESULTS: The factors "cooling protocol" (P=0.0058) and "application" technique (P=0.0001) influenced the fracture resistance of the crowns. For pressed veneer technique, the P2S (4608.9±464.5). A presented significantly higher results than that P2F(3621.1±523.0)BCD (Tukey's test). For the stratified technique, this difference was not observed (P>0.05). The thickness of the veneering ceramic was not significant regardless of the cooling protocol and technique (P>0.05). The predominant failure mode was chipping of the ceramic veneer originating in the subsurface. CONCLUSIONS: The pressed technique, used with a slow-cooling protocol, leads to the best outcome for the veneering of all-ceramic crowns. Key words:Zirconia, ceramics, cooling protocol, thickness, application technique.

Survival probability of zirconia-reinforced lithium silicate ceramic: Effect of surface condition and fatigue test load profile.

OBJECTIVES: The present investigation evaluated the step stress accelerated test (SSALT) load profiles on the survival probability of a glass ceramic under two surface conditions (polished or roughened). METHODS: Suprinity-ZLS blocks (Vita Zhanfabrik) were shaped into cylinders, cut in a sawing machine, and crystalized according to the manufacturer's instructions. 60 discs were obtained (Ø=12mm, thickness=1.2mm) and randomly assigned into two surface conditions: "p" polished surface (400-1200-grit SiC papers), and "r" roughened surface (200-grit SiC papers). Profilometry was performed in all discs to evaluate average surface roughness prior to flexural fatigue strength testing. 3 discs of each group were submitted to biaxial flexural strength in an universal testing machine (0.5mm/min) and the mean load to failure (N) was calculated to determine SSALT profiles. 27 specimens per surface condition were assigned into three profiles - Mild (n=9), Moderate (n=9), and Aggressive (n=9), and submitted to the fatigue test (60-320N, 140,000 cycles at 1.4Hz). The results were analyzed using the Kaplan-Meier and Wilcoxon tests (5%), 2-way ANOVA and Tukey test (α=5%). RESULTS: Kaplan-Meier and generalized Wilcoxon showed (P=0.002) that polished groups showed higher survival probability than roughened condition (P<0.05). A rough internal surface impacted deleteriously on the fatigue strength and reliability of ZLS ceramic. Both surface conditions were more sensitive to the aggressive profile than the other profiles, even worst for the roughened group. Regardless the load profile, 0% survival probability was observed at 384MPa for polished condition. While for roughened, aggressive tested specimens did not survived 147MPa followed by moderate at 312MPa and mild at 384MPa. The failure modes showed fracture marks originating from superficial grooves for both surface conditions. SIGNIFICANCE: Polished specimens are sensitive to the load profile variation, confirming the effect of surface morphology on the fatigue results.

A Powdering Technique for Veneering Zirconia and Its Effect on the Flexural Strength of Ceramic Bilayers.

The aim of this study was to assess the powdering technique and its effects on the flexural strength of bilayered zirconia. Bars made of zirconia partially stabilized by yttrium (Y-TZP) received porcelain by the following techniques (n = 10 per group): (1) L: VM9 application; (2) P: powdering technique + VM9 application; (3) C: Y-TZP coloring before sintering + Y-TZP sintering + VM9 application; or (4) CP: Y-TZP coloring before sintering + Y-TZP sintering + powdering technique + VM9 application. The powdering technique consisted of the application of VM9 margin powder followed by sintering. The samples were subjected to a 4-point flexural strength test and contact angle. Data were analyzed by one-way ANOVA and Tukey test (α = 5%). Surface treatments did not affect the flexural strength of bilayered specimens (P = .1264), but contact angle was affected by surface treatments (P < .0001), wherein the association of coloring and powdering (CP) reached higher values of wettability. Powdering did not affect the flexural strength of bilayered specimens, but did increase the Y-TZP wettability.

Reabilitação estético funcional em paciente maxilectomizado ­ acompanhamento de quatro anos / Functional and aesthetic rehabilitation in maxilectomized patients ­ 4-years follow up

O ameloblastoma é um tumor odontogênico benigno, localmente invasivo, capaz de infiltrar-se pelos espaços medulares do osso e, quando em estágio inicial, geralmente não apresenta indícios radiográficos ou macroscópicos. Muitas vezes, pacientes submetidos a tratamento ressectivo perdem grande parte da maxila ou mandíbula, necessitando de uma alternativa de tratamento para restabelecer a função e a estética. O objetivo deste relato de caso foi apresentar um acompanhamento de quatro anos de uma reabilitação com implantes zigomáticos em paciente submetido à ressecção de maxila anterior devido a um tumor odontogênico do tipo ameloblastoma. Quatro meses após a realização da cirurgia de ressecção do ameloblastoma na região anterior de maxila, foram instalados dois implantes com ancoragem zigomática no lado esquerdo, um implante com ancoragem zigomática no lado direito e dois implantes regulares hexágono externo no lado direito. Em seguida, foi feita uma prótese provisória imediata. Seis meses depois, os implantes foram carregados com a prótese final em resina acrílica. Após quatro anos de acompanhamento, não foram observados sintomas dolorosos, inflamação ou infecção peri-implantar, instabilidade do implante ou reabsorção óssea. No presente caso, a reabilitação da maxila atrófica com implantes no osso zigomático proporcionou bons resultados funcionais e estéticos a longo prazo. Assim, o uso de implantes zigomáticos associados a implantes padrão oferece vantagens na reabilitação de maxilares severamente reabsorvidos, principalmente quando a indicação é feita corretamente e com o conhecimento da técnica cirúrgica. (AU)

Ameloblastoma is a benign, locally invasive odontogenic tumor capable of infiltrating the bone marrow spaces, and when at the initial stage, it generally does not show radiographic or macroscopic evidence. Patients undergoing resection treatment lose a large part of the maxilla or mandible, requiring an alternative treatment to re-establish the function and aesthetics. The objective of this case report was to present a 4-years follow-up of a rehabilitation with zygomatic implants in a patient submitted to anterior maxillary resection due to an odontogenic tumor of the ameloblastoma type. After 4 months of the ameloblastoma resection surgery in the anterior maxillary region, 2 implants were placed with zygomatic anchoring on the left side, 1 implant with zygomatic anchoring on the right side and 2 regular external hexagon implants placed on the right side and then it was done an immediate provisional prosthesis. Six months later, the implants were loaded with the fi nal acrylic resin prosthesis. After 4-years of follow-up no painful symptoms, inflammation or peri-implant infection, implant instability or bone resorption were observed. In the present case, the atrophic maxilla rehabilitation with implants in the zygomatic bone provided long-term functional and aesthetic results. Thus, the zygomatic implants associated with standard implants offers advantages in severely reabsorbed maxillae rehabilitation, especially when the indication is made correctly and also with the knowledge of the surgical technique. (AU)

Effect of different impression methods and ceramic materials on adaptation of inlays / Efeito de diferentes métodos de moldagem e materiais cerâmicos na adaptação de inlays

Objective: The aim of this study was to evaluate the internal and marginal adaptation of inlays fabricated from different types of impressions (conventional and digital) and different ceramics (feldspathic and lithium disilicate). Material and Methods: Forty premolars were prepared for all-ceramic inlay restoration and assigned to 4 groups (n=10), according to the impression method (conventional with addition silicone and digital impression) and ceramic type (lithium disilicate and feldspathic ceramic blocks). For each type of impression, 10 inlays were milled from lithium disilicate blocks and the other 10 from feldspathic ceramic blocks in a CAD-CAM facility. The internal adaptation was analyzed by the replica technique. The marginal fit was analyzed under a stereo microscope by directly measuring the gap formed between the inlay and the tooth in the proximal and occlusal regions. Results: The marginal or internal adaptations were not affected by type of impression (conventional = digital impression), irrespective of the ceramic type. Only the internal adaptation was affected by the material type, i.e., feldspathic ceramic had lower values than lithium dissilicate ceramic, when considering the digital impression. Conclusion: The conventional and digital impressions promoted similar marginal and internal adaptation for feldspathic and disilicate ceramic inlays. For the digital impression the feldspathic inlays showed better internal adaptation than lithium dissilicate inlays. (AU)

Objetivo: O objetivo deste estudo foi avaliar a adaptação interna e marginal de inlays confeccionadas a partir de diferentes tipos de moldagens (convencional e digital) e diferentes materiais cerâmicos (feldspática e dissilicato de lítio). Materiais e Métodos: Quarenta pré-molares foram preparados para inlay totalmente cerâmica e distribuídos em 4 grupos (n = 10) segundo o método de moldagem (convencional com silicone de adição e moldagem digital) e tipo cerâmica (dissilicato de lítio e blocos de cerâmica feldspática). Para cada tipo de moldagem, 10 inlays foram confeccionadas a partir de pastilhas de dissilicato de lítio e as outras 10 de blocos de cerâmica feldspática, por meio do sistema CAD-CAM. A adaptação interna foi analisada pela técnica da réplica. O ajuste marginal foi analisado com estéreo microscópio medindo diretamente o espaço entre a inlay e o dente nas regiões proximal e oclusal. Resultados: As adaptações marginais e internas não foram afetadas pelo tipo de moldagem (convencional = impressão digital), independentemente do tipo de cerâmica. Somente a adaptação interna foi afetada pelo material, sendo que a cerâmica feldspática apresentou menores valores que a cerâmica de dissilicato, considerando a moldagem digital. Conclusão: As moldagens convencional e digital promoveram adaptação marginal e interna semelhante de inlays de cerâmica feldspática e dissilicato testadas. Para moldagem digital, a cerâmica feldspática mostrou melhor adaptação interna do que a dissilicato de lítio (AU)

Protocolo totalmente cerâmico: uma opção para desafios estéticos / Full-ceramic, complete, fixed implant-supported prosthesis: an option for esthetic challenges

A indicação do uso de sistemas totalmente cerâmicos (infraestrutura em zircônia) para a confecção de próteses implantossuportadas ainda causa questionamentos ao profissional quanto à durabilidade e recomendação desta solução protética. No entanto, o estabelecimento das vantagens da escolha do uso de infraestruturas em zircônia para a confecção de próteses totais fixas com implantes tem sido notável. Logo, este trabalho apresenta um relato clínico planejado e executado sob os parâmetros de planejamento reverso e funcional que norteiam a Implantologia. Cabe ressaltar que o objetivo de todo tratamento odontológico é a satisfação do paciente e a obtenção de estética, com base em evidências científicas.

The indication of full ceramic systems (zirconia infraestructure) to fabricate implant-supported prostheses still causes some professional concerns regarding their durability and recommendation of a prosthetic solution. Nevertheless, the advantages of zirconia infra-estructures for total fixed prostheses over dental implants has been recognized. Thus, this paper presents a clinical report planned and executed under the reverse functional treatment planning at the implant dentistry field. It is important to highlight that the aim of all dental treatment is patient satisfaction and esthetics, based on scientific evidences.

Microstructural analysis and reliability of monolithic zirconia after simulated adjustment protocols.

OBJECTIVE: To investigate the microstructural properties and reliability of zirconia partially stabilized by yttrium oxide (Y-TZP) for use in monolithic form (Vita YZ HT, Vita Zahnfabrik, Germany) after different clinical adjustment protocols simulation. One-hundred and sixty two Y-TZP discs of high translucency were divided into 6 groups (n=27), according to simulated adjustments: S-Y-TZP as sintered; G-glazed Y-TZP; DbG-Y-TZP with diamond bur adjustment simulation followed by glaze application; GDb-glazed Y-TZP adjusted with diamond bur; DbDrG-Y-TZP with adjustment simulation with diamond bur and polishing kit (diamond rubber), followed by glaze; GDbDr-glazed Y-TZP with adjustment simulation with diamond bur followed by polishing kit. METHODS: After monotonic testing under biaxial flexure (n=3), remaining specimens were distributed into 3:2:3 ratio and tested under step-stress accelerated life testing. Specimens were evaluated in a stereomicroscope and SEM. Microstructure was analyzed by X-ray diffraction and mean surface roughness (Ra). Survival data were used to calculate Weibull's beta value (ß) and reliability for missions of 300,000 and 600,000 cycles at 200N. Ra data were statistically analyzed by 1-way ANOVA and Tukey's test (both, a=5%). RESULTS: The untreated HT zirconia (S) presented a lower probability of survival after 600,000 cycles at 200N, compared to HT zirconia adjusted with diamond bur and glazed (DbG), and after final polishing with polishing kit (GDbDr). Final polishing with diamond rubber (GDbDr) resulted in a more homogeneous surface compared to glazed samples (G, DbG and DbDrG). SIGNIFICANCE: HT zirconia is more likely to present increased survival when glazed after diamond adjustments (DbG) or when it is finished with polishing kit (GDbDr).

Reabilitação estético funcional ­ conjugação de restaurações em resina direta, laminados ultrafinos e onlays cerâmicas / Functional aesthetic rehabilitation ­ conjugation of restorations in direct resin, ultra-thin laminates and ceramic onlays

A dinâmica clínica em reabilitação oral requer um planejamento criterioso para conduzir o sucesso do tratamento, exemplificado pela atenção às características individuais de cada paciente, auxiliando na escolha de materiais restauradores que possibilitem a preservação da estrutura dental e que apresentem propriedades favoráveis para funções biomecânicas similares aos dentes naturais. Uma opção válida é propiciar o restabelecimento estético e funcional através de restaurações cerâmicas, primordialmente associadas ao correto diagnóstico e planejamento. O objetivo deste trabalho foi abordar os principais aspectos relacionados à reabilitação oral, utilizando cerâmicas odontológicas, por meio do relato de um caso. Para maior previsibilidade do mesmo e para otimização do tempo de trabalho, utilizou-se DSD, enceramento diagnóstico e matriz de silicone translúcida associada com resina composta flow. A harmonização e o equilíbrio do sistema pelo restabelecimento da oclusão através do trabalho baseado na DVO e nos desgastes oclusais também são de extrema importância para um resultado final efetivo. Assim, respaldando-se também pela literatura atual, nota-se que laminados oclusais ultrafinos, resinas compostas e cerâmicas são capazes de satisfazer os requisitos biomiméticos, salvando tecidos dentários e restaurando estética.

The clinical dynamics of oral rehabilitation requires careful planning to conduct the sucess of a clinical case, which is exemplified by the attention to the individual characteristics of each patient. Giving support for the choice of the restorative materials which enable dental structure preservation and show favorable properties for biomechanical functions similar to the natural tooth. A valid option is to provide the aesthetic and functional restoration through ceramic restorations, primarily associated to correct diagnosis and planning. The aim of this research is to approach the main aspects related to oral rehabilitation, using dental ceramics through this case report. For a greater predictability of the case and optimization of the working time, DSD, mock-up and translucent silicone matrix approached with flow composite resin were used. The standardization and balance of the system through the occlusal reestablishment according to the VOD and dental attrition are extremely important for an effective end result. Thus, based on the current literature, it is noticed that ultrathin occlusal laminate, composite resin and ceramics are able to meet the biomimetic requeriments, preserving dental tissues and restoring aesthetics.

Bonding of the Polymer Polyetheretherketone (PEEK) to Human Dentin: Effect of Surface Treatments.

Polyetheretherketone (PEEK) is a material suitable for frameworks of fixed dental prostheses. The effect of different surface treatments on the bond strength of PEEK bonded to human dentin was evaluated. One hundred PEEK cylinders (3 mm×3 mm) were divided into five groups according to surface treatment: silica coating, sandblasting with 45 µm Al2O3 particles, etching with 98% sulfuric acid for 5, 30 and for 60 s. These cylinders were luted with resin cement onto 50 human molars. First, each tooth was embedded in epoxy resin and the buccal dentin surface was exposed. Then, two delimited dentin areas (Æ:3 mm) per tooth were etched with 35% phosphoric acid and bonded with a two-step self-priming adhesive system. After the luting procedure the specimens were stored in water (24 h/37 °C). Shear bond strength (SBS) was tested using a universal testing machine (crosshead speed 0.5 mm/min; load cell 50 kgf) and failure types were assessed. Stress data (MPa) were analyzed using the Kruskal-Wallis test. Comparison of the proportions of different failure types was performed using the Bonferroni method (p<0.05). Kruskal-Wallis demonstrated that differences among groups were not significant (p=0.187). Mean SBS were as follows: silica coating, 2.12±1.12 MPa; sandblasting, 2.37±0.86 MPa; sulfuric acid 5 s, 2.28±1.75 MPa; sulfuric acid 30 s, 1.80±0.85 MPa; sulfuric acid 60 s, 1.67±0.94 MPa. Adhesive and mixed failures were predominant in all groups. Both physical and chemical surface treatments produced adhesion between PEEK, resin cement and dentin.

Bonding of the Polymer Polyetheretherketone (PEEK) to Human Dentin: Effect of Surface Treatments

Abstract Polyetheretherketone (PEEK) is a material suitable for frameworks of fixed dental prostheses. The effect of different surface treatments on the bond strength of PEEK bonded to human dentin was evaluated. One hundred PEEK cylinders (3 mm×3 mm) were divided into five groups according to surface treatment: silica coating, sandblasting with 45 μm Al2O3 particles, etching with 98% sulfuric acid for 5, 30 and for 60 s. These cylinders were luted with resin cement onto 50 human molars. First, each tooth was embedded in epoxy resin and the buccal dentin surface was exposed. Then, two delimited dentin areas (Æ:3 mm) per tooth were etched with 35% phosphoric acid and bonded with a two-step self-priming adhesive system. After the luting procedure the specimens were stored in water (24 h/37 °C). Shear bond strength (SBS) was tested using a universal testing machine (crosshead speed 0.5 mm/min; load cell 50 kgf) and failure types were assessed. Stress data (MPa) were analyzed using the Kruskal-Wallis test. Comparison of the proportions of different failure types was performed using the Bonferroni method (p<0.05). Kruskal-Wallis demonstrated that differences among groups were not significant (p=0.187). Mean SBS were as follows: silica coating, 2.12±1.12 MPa; sandblasting, 2.37±0.86 MPa; sulfuric acid 5 s, 2.28±1.75 MPa; sulfuric acid 30 s, 1.80±0.85 MPa; sulfuric acid 60 s, 1.67±0.94 MPa. Adhesive and mixed failures were predominant in all groups. Both physical and chemical surface treatments produced adhesion between PEEK, resin cement and dentin.

Resumo O poli-éter-éter-cetona (PEEK) é um material indicado para as estruturas de próteses parciais fixas. O efeito de diferentes tratamentos de superfície na resistência de união entre PEEK e dentina humana foi avaliado. Cem cilindros de PEEK (3 mm×3 mm) foram divididos em cinco grupos de acordo com tratamento de superfície: silicatização, jateamento com partículas de Al2O3 45 µm, condicionamento com ácido sulfúrico 98% por 5, 30 e 60 s. Esses cilindros foram cimentados com cimento resinoso em cinquenta molares humanos. Primeiro, cada dente foi incluído em resina epóxica e a superfície dentinária vestibular foi exposta. Depois, duas áreas (Æ:3 mm) em dentina/por dente foram delimitadas, condicionadas com ácido fosfórico a 35% e receberam aplicação de um sistema adesivo de dois passos. Após o procedimento de cimentação, as amostras foram armazenadas em água (24 h/37 °C). A resistência da união ao cisalhamento (SBS) foi testada em uma máquina universal de ensaios (velocidade 0,5 mm/min; célula de carga 50 kgf), e foram avaliados os tipos de falha. Os dados de tensão (MPa) foram analisados pelo teste de Kruskal-Wallis. A comparação das percentagens de diferentes tipos de falha foi realizada utilizando o método de Bonferroni (p<0,05). O teste de Kruskal-Wallis demonstrou que as diferenças entre os grupos não foram significantes (p=0,187). As médias de SBS foram: silicatização, 2,12±1,12 MPa; jateamento, 2,37±0,86 MPa; ácido sulfúrico por 5 s, de 2,28±1,75 MPa; ácido sulfúrico por 30 s, 1,80±0,85 MPa, ácido sulfúrico por 60 s, 1,67±0,94 MPa. Falhas adesivas e mistas foram predominantes em todos os grupos. Ambos tratamentos de superfície, físicos e químicos, promoveram adesão entre PEEK, cimento resinoso e dentina.

Laminados cerâmicos anteriores e posteriores em paciente com desordem funcional estabilizada / Anterior and posterior porcelain laminate veneers in a patient with stabilized functional disorder

A necessidade de reabilitação protética de um paciente com diagnóstico de apertamento dental em cêntrica e excêntrica (bruxismo) pode, por vezes, gerar dúvidas ao profissional durante a elaboração do planejamento e a execução de tratamentos reabilitadores. O estabelecimento de critérios seguros para seleção do material e a transmissão de cargas para o remanescente dental são questionamentos frequentes. Este trabalho apresentou um relato de caso clínico planejado e executado sob parâmetros funcionais e de análise de sorriso, que norteiam a projeção de tratamentos reabilitadores estéticos. Cabe ressaltar que o objetivo de todo tratamento é preservar o remanescente dental, com base em evidências científi cas e nos princípios da Odontologia minimamente invasiva, com a fi nalidade de garantir longevidade e previsibilidade clínica.

Fracture of Zirconia Abutment with Metallic Insertion on Anterior Single Titanium Implant with Internal Hexagon: Retrieval Analysis of a Failure.

This case report presents a retrieval analysis of a screw-retained one-piece restoration with the veneering ceramic fired directly onto the zirconia abutment that fractured during insertion. A patient who experienced root fracture of a maxillary left central incisor received a titanium implant on the same day as extraction. After delayed implant loading, a two-piece zirconia abutment with metallic insertion was customized. Upon installation, a horizontal fracture of the crown just above the metallic portion was detected. The retrieval analysis of a fractured zirconia abutment showed crack formation and diffusion of glaze material that expanded the crack line during firing.

Influence of insertion techniques for resin cement and mechanical cycling on the bond strength between fiber posts and root dentin.

PURPOSE: To evaluate the effect of the insertion technique for resin cement and mechanical cycling on the bond strength between fiber posts and root dentin. MATERIALS AND METHODS: Sixty-four single-rooted bovine teeth were endodontically prepared to receive glass-fiber posts. The insertion of cement into the root canal was performed using one of the following techniques: POS, insertion with the post; LEN, the use of a lentulo-type drill; EXP, insertion with a straight-tip explorer; or CEN, the use of a Centrix syringe. Half of the specimens were mechanically cycled. All specimens were sectioned into slices of 1.8 mm for the push-out test and 0.5 mm for analysis of the cement layer quality. RESULTS: The insertion technique affected the interaction between factors (bond strength and mechanical cycling; p < 0.0001). Insertion of the Centrix syringe after mechanical cycling showed the highest bond values (13.6 ± 3.2 MPa). Group-to-group comparisons for baseline and cycled conditions indicated that mechanical cycling significantly influenced the bond strength (p < 0.0001) of the POS and CEN groups. The quality of the cement layer did not differ between the techniques when evaluated in the middle (p = 0.0612) and cervical (p = 0.1119) regions, but did differ in the apical region (p = 0.0097), where the CEN group had better layer quality for the two conditions tested (baseline and cycled). CONCLUSION: The use of the Centrix syringe improved the homogeneity of the cement layer, reducing the defects in the layer and increasing adhesive strength values to dentin, even after mechanical cycling.