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This systematic review aims to explore and compile the effect of adhesive luting on the mechanical properties of dental ceramics used as restorative materials.The PubMed/MEDLINE, Web of Science and Scopus databases were searched on January 31st, 2021 to select laboratory studies written in English, without publishing-date restrictions, which compared the mechanical properties of commercially available dental ceramics as restorative materials luted using adhesive vs non-adhesive strategies. A total of 20 (out of 2039) studies were eligible and included in the analysis. Two authors independently selected the studies, extracted the data and assessed the risk of bias. Mean differences (RevMan5.1, random effects model, α = 0.05) were obtained by comparing resistance values of adhesive and non-adhesive conditions (global analysis). Subgroup analyses were performed considering ceramic composition and aging.In the global analysis, adhesive luting induced higher mechanical resistance values compared to non-adhesive luting (p ≤ 0.01). The same effect was observed for glass and alumina ceramics (p ≤ 0.01), but not for zirconia polycrystals (p = 0.83). Adhesive luting was favorable in both the aged and non-aged subgroup analysis (p ≤ 0.01). High heterogeneity was found in all meta-analyses. All analyzed studies in the systematic review scored negatively for risk of bias in most of the factors considered.Adhesive luting reinforces the mechanical properties of dental ceramics used as restorative materials, with the exception of zirconia polycrystals.

Objective: This investigation evaluated the effect of two sintering modes of a translucent zirconia (Y-TZP) on its surface roughness, topography, phase-transformation (t → m), translucency and biaxial flexure fatigue strength. Materials and Methods: To do so, 50 Y-TZP discs (Ø = 15 mm; thickness = 1.2 mm; IPS e.max ZirCAD LT) were prepared and divided into two groups: Standard mode (SM) and Fast mode (FM). Staircase fatigue testing was performed (piston-on-three balls set-up, ISO 6872:2015), as well as surface roughness, profilometry, scanning electron microscopy (SEM-FEG), energy dispersive X-ray spectroscopy (EDX), phase transformation (t → m) using X-ray diffraction analysis (XRD), translucency parameter analysis (TP and TP00) and fractography. Results: The results showed no statistical significant differences for roughness parameters (p > 0.05, SM: Ra = 0.13 ± 0.02, Rz = 1.21 ± 0.26 and RSm = 24.91 ± 2.19; FM: Ra = 0.14 ± 0.03, Rz = 1.32 ± 0.25 and RSm = 24.68 ± 2.16) or flexural fatigue strength (SM: 512 (464–560) MPa; FM: 542 (472–611) MPa) between the groups. In addition, similarity in surface morphological features (SEM and profilometry), composition and phases (EDX and XRD) was observed between the firing protocols. Fractography showed that the failure origin occurred on the tensile side. Sintering mode did not affect the TP (F = 0.001, p = 0.97) and TP00 (F = 0.12, p = 0.72). Conclusions: Therefore, the fast-sintering mode is suggested as a viable alternative to the standard mode since it does not influence the evaluated surface morphology, microstructure, fatigue strength and translucency of a translucent monolithic zirconia. Clinical Significance: The fast sintering mode is a viable alternative for zirconia without compromising its topography, microstructure, mechanical performance or translucency.

This study aims to characterize the effect of shading techniques on the fatigue behavior of a 4YSZ ceramic (4 mol% yttrium stabilized zirconia) adhesively bonded to a dentin analogue (fiber-reinforced epoxy resin). 4YSZ ceramic discs (IPS e.max ZirCAD, Ø = 10 mm and 1 mm of thickness) were allocated according to the factor 'shading technique' into 4 groups: Brush- unshaded ceramic disc (IPS e.max ZirCAD BL) pigmented at the pre-sintered stage with pigment solution applied manually using a round liner brush; Immersion- unshaded ceramic disc pigmented through immersion in the solution for 1 s on only one side of the ceramic disc; Manufacturer- specimens already shaded by the manufacturer (IPS e.max ZirCAD MT A2 - Manufacturer group); Control- a control condition with absence of pigment (i.e. non-pigmented specimens). The specimens were sintered and a spectrophotometer (SP60, EX- Rite) was used to ensure that the same perceived color (i.e. pigment saturation) was achieved in the different shading strategies (Manufacturer, Brush or Immersion groups). To do so, the color differences (ΔE

How best to restore endodontically treated teeth is still unclear because many types of material and techniques are involved.The purpose of this overview of systematic reviews of clinical studies was to assess the available evidence-based literature on the influence of associated clinical factors on the clinical performance (survival, failure rate, or success) of restored endodontically treated teeth.PubMed, Scopus, and Web of Science were searched from inception until September 27, 2021, to identify systematic reviews. Two reviewers independently screened titles, abstracts, and full-text articles, and each reviewer extracted the data of half of the included studies. A single reviewer with an independent verifier completed the quality appraisal. A descriptive analysis of the collected data was made.A total of 36 systematic reviews fulfilled the inclusion criteria. The factors most assessed were the type of coronal restorative technique (n=22) and type of post (n=22). The results indicated that metal and fiber posts seem to present similar clinical performance, endocrowns could be a suitable restorative option, there is no evidence to confirm whether single crowns are better or worse than direct restoration, the maintenance of the coronal structure is a fundamental factor, and the ferrule effect is still a controversial topic. Most of the studies (n=30, 81%) presented a final Grading of Recommendations, Assessment, Development and Evaluations (GRADE) rating of "critically low."The post type does not appear to influence the clinical performance of restored endodontically treated teeth. However, conclusive evidence to suggest how different materials or techniques for restoring coronal tooth structure affect the clinical performance of such restorations, as well as the impact of the ferrule effect, is still lacking.

Dois casos clínicos são apresentados para explorar as diferenças técnicas e discutir as vantagens e desvantagens do uso de zircônia folheada ou monolítica para confeccionar coroas únicas posteriores. O primeiro caso descreve as etapas clínicas na fabricação de uma coroa monolítica em um segundo pré-molar inferior esquerdo usando zircônia de alta translucidez. Mostra a utilização de um preparo dentário conservador baseado nas propriedades mecânicas superiores que este material apresenta, bem como nas características ópticas finais alcançadas pelo sombreamento e coloração. No segundo caso, foi realizado um tratamento restaurador convencional em bicamada com estrutura de zircônia seguida de estratificação com cerâmica de feldspato no primeiro molar inferior esquerdo. A literatura recente indica que cada uma dessas alternativas restauradoras apresenta vantagens e desvantagens específicas. Fatores como desempenho mecânico, fratura, características estéticas, sucesso clínico, taxas de complicações, desempenho de adesão e desgaste do antagonista são discutidos comparando os dois conjuntos restauradores. Os dados destacam que as coroas monolíticas evitam um grande problema relatado nas restaurações de duas camadas: o lascamento da cerâmica de recobrimento. As coroas monolíticas também permitem preparações dentárias minimamente invasivas, aumentando assim a preservação do remanescente dentário. No entanto, faltam dados que sustentem a similaridade do desempenho estético entre as montagens monolítica e bicamada, sendo a previsibilidade de uso restrita para a região posterior, pois casos que demandam alto apelo estético continuam a utilizar fundamentalmente as restaurações bicamada. Não foram encontradas falhas, e a satisfação do paciente foi relatada em ambas as técnicas após o acompanhamento de 12 meses.

OBJECTIVE This study aimed to evaluate whether a master and PhD thesis in Brazilian graduate programs in dentistry can be based on a systematic review (SR). METHODS In this cross-sectional study, we surveyed the coordinators of Brazilian graduate programs in dentistry using a self-administered questionnaire including questions about whether an SR meets requirements for approval of a master or PhD thesis, instructions regarding how to use an SR as the method for a master or PhD thesis, and reasons and barriers that SRs were not recognized as acceptable for a master or PhD thesis. The responses were analyzed descriptively, and tables and graphs were created to summarize the data. RESULTS Among 101 graduate programs invited to participate in the study, 38 (37.6%) returned the questionnaire. Over three-quarters of surveyed programs (n = 30, 78.1%) answered that SRs, in whole or in part, meet the criteria for a master or PhD thesis. Likewise, most programs answered that a master or PhD thesis could be exclusively based on an SR (n = 28, 73.7%). The same number of programs pointed out that one possible reason for not recognizing SRs as a master or PhD thesis is either the lack of SR expertise among committee members (n = 28, 73.7%) or the lack of adequate training of candidates in SR methodology (n = 26, 68.4%). CONCLUSIONS SRs are well accepted as a master or PhD thesis by Brazilian graduate programs in dentistry. Educational initiatives should be encouraged to promote understanding of SR methodology and increase acceptance among graduate programs worldwide.

This study compared the physical properties of conventional and monolithic yttria-zirconia (Yz) materials after low-temperature degradation (LTD). Bar-shaped specimens (2.0 mm thick × 4.0 mm wide × 16.0 mm in length) were produced. Autoclave aging was executed at 134°C under 2 bar pressure for 5 h. The surface characteristics were assessed using a confocal laser microscope, microstructural phase alterations via an X-ray diffractometer (XRD), 3-point flexural strength using a universal testing machine, Vickers microhardness via a digital microhardness tester, and toughness using a durometer. Fractured specimens and indented surfaces was observed via a scanning electron microscope for fractography characterization. All of the data underwent specific statistical tests considering their distribution and homogeneity. Regarding topography, different Yz materials were very similar after LTD. Conventional Yz materials were smoother. The XRD data support that both materials were mainly composed of tetragonal crystals, whereas slight monoclinic peaks were detected. Monolithic Yz showed higher flexural strength than conventional Yz. All of the fractures started on surface defects at the side where tensile stress was concentrated (opposite to load application) and propagated to the opposite side. Vickers microhardness and toughness analysis found that conventional Yz had higher performance than monolithic Yz. This study has found that there are slight differences in strength, hardness, and toughness between conventional and monolithic yttria-stabilized zirconia ceramics, although both materials demonstrate adequate performance for clinical use.

Information regarding the masking ability of ceramic crowns over different implant abutment materials is scarce.The purpose of this in vitro study was to evaluate the masking ability of different monolithic or bilayer ceramic materials with different thicknesses over substrates indicated for implant restorations by using opaque and translucent evaluation pastes.Disk-shaped specimens, shade A1 (VITA Classic; Ø10×1.5 to 2.5 mm), of different ceramics (a bilayer system [yttria-stabilized zirconia infrastructure+porcelain veneer: Zir+Pc] and monolithic systems [lithium disilicate under low, medium, or high translucency: LtLD, MtLD, or HtLD, respectively, and a high-translucent yttria-stabilized zirconia: HtZir]) were made (n=4). The color difference (ΔEThe most predictable masking ability was seen with Zir+Pc regardless of the evaluation paste used. Nevertheless, under 1.5-mm thickness, Zir+Pc did not adequately mask Ti (ΔEMonolithic ceramics should be used with caution over discolored implant abutments. Bilayer systems (Zir+Pc) were the most predictable approach to adequately masking discolored substrates such as PEEK or Ti. An increased restoration thickness provided higher masking ability for all restorative materials tested.

It aims on evaluate the effect of the test environment on static fatigue behavior of lithium disilicate-based (LD), and yttrium oxide-stabilized zirconia (YSZ) ceramics. Specimens of LD (IPS e.max CAD, Ivoclar Vivadent) and YSZ (IPS e.max ZirCAD MO, 3 mol% Y2O3, Ivoclar Vivadent) were randomly allocated into three groups: tested in air, inert (paraffin oil, Sigma Aldrich) or distilled water. The static fatigue test (n=15) was performed using a piston-on-three ball assembly, adapted from ISO 6872, as follows: starting load 100 N for LD and 300 N for YSZ; loading application time set to 1 hour for each loading step; step size of 50 N for LD and 100 N for YSZ, applied successively until fracture. Data from static fatigue strength (MPa) and time to fracture (hours) were recorded. Fractographic analysis was executed. Survival analysis corroborates absence of influence of environment on static fatigue outcomes (fatigue strength, time to fracture and survival rates) for YSZ. For LD, specimens tested in air presented statistically superior survival rate and static fatigue strength (p= 0.025). In regards of time to fracture, LD tested in air were superior than when tested in distilled water (p=0.019) or inert (p=0.017) environments. No statistical differences for Weibull modulus were observed. Failures started on the tensile stress surface. Thus, the test environment did not affect slow crack growth (SCG) mechanisms during static fatigue test of YSZ ceramics, but it plays a significant role for the static fatigue behavior of lithium disilicate-based glass ceramics, indicating a high susceptibility to SCG. Resumo O presente estudo objetivou investigar a influência do ambiente de teste no comportamento a fadiga estática (resistência à fratura e tempo para falha) de cerâmicas à base de dissilicato de lítio (LD) e zircônia estabilizada com ítria (YSZ). Espécimes de LD (IPS e.max CAD, Ivoclar Vivadent) e YSZ (IPS e.max ZirCAD MO, 3mol% Y2O3, Ivoclar Vivadent) foram obtidos e alocados aleatoriamente em três grupos: testado em ar, em líquido inerte (óleo de parafina) ou em água destilada. O teste de fadiga estática (n= 15) foi realizado usando o teste pistão sobre três esferas, ISO 6872, da seguinte forma: carga inicial 100 N para LD e 300 N para YSZ; tempo de aplicação de carregamento definido para 1 hora para cada etapa de carregamento; tamanho do passo de 50 N para LD e 100 N para YSZ, aplicados sucessivamente até a fratura. Dados de resistência à fadiga estática (MPa) e tempo até a fratura (horas) foram registrados. A análise fractográfica foi executada. A análise de sobrevivência corrobora a ausência de influência do ambiente de teste nos resultados de fadiga estática (resistência à fadiga, tempo de fratura e taxas de sobrevivência) para a YSZ. Para LD, os corpos de prova testados em ar apresentaram taxa de sobrevivência e resistência à fadiga estática estatisticamente superiores (p= 0,025). Em relação ao tempo de fratura, os espécimes LD testados em ar foram superiores aos testados em água destilada (p= 0,019) ou em ambiente inerte (p= 0,017). Não foram observadas diferenças estatísticas para o módulo de Weibull. Todas as falhas começaram no lado onde se concentra a tensão de tração (lado de baixo) durante o teste. Com base nisso, observa-se que o ambiente de teste não afetou os mecanismos de crescimento lento de trinca durante o teste de fadiga estática da cerâmica YSZ, mas desempenha um papel significativo na resistência à fadiga estática da cerâmica de vidro à base de dissilicato de lítio, indicando alta susceptibilidade ao crescimento lento e subcrítico de trincas.

To evaluate whether an adhesive application after surface treatment on a lithium disilicate ceramic (LD) has an influence on its load-bearing capacity under fatigue.LD discs (Ø= 10 mm; thickness= 1 mm) were allocated into 8 groups (n= 15), considering 3 factors: "ceramic surface treatment" - HF: hydrofluoric acid + universal primer application; or MEP: single-component ceramic primer; "adhesive application" - with or without; and "aging protocol" - baseline: 24 h to 7 days; or aging: 180 days of storage + 25,000 thermal cycles. The LD discs were adhesively bonded to glass fiber-reinforced epoxy resin discs (Ø= 10 mm; thickness= 2 mm) and stored according to the condition and each group. Cyclic fatigue testing (initial load= 100 N; step size= 100 N until600 N and after step size= 25 N to failure; 10,000 cycles/step; 20 Hz frequency) was performed. Fractographic and adhesive interface analyzes were also performed. The collected data were then analyzed by Kaplan Meier and Mantel-Cox tests and One-way ANOVA.The adhesive application in the baseline condition had no influence on the load-bearing capacity under fatigue when the HF surface treatment was performed, however, adhesive application for the MEP treatment led to worse results than without it. The adhesive application in the aged condition showed worse fatigue outcomes for both treatments. All specimens presented radial cracks. MEP treatment followed by adhesive application presented the thickest luting layer.The adhesive application after surface treatments of a lithium disilicate glass-ceramic is detrimental to its load-bearing capacity under fatigue when adhesively luted onto a supporting substrate.

This study evaluated the influence of ceramic surface conditioning and storage regimen (baseline vs. aging) on the fatigue performance of simplified lithium disilicate glass-ceramic restorations. A total of 90 ceramic discs (O= 10 mm; thickness= 1.0 mm) were allocated into 6 groups (n= 15), considering 2 factors: “ceramic surface treatment” – CA (only silane-based coupling agent, Monobond N), HF (5% hydrofluoric acid etching), or HF+CA (5% HF acid etching plus silane-based coupling agent); and “storage regimen” – baseline (24 hours – 5 days of distilled water at 37 °C), or long-term aging (180 days of distilled water at 37 °C + 25,000 thermal cycles). After intaglio ceramic conditioning, adhesive bonding (Multilink N) was performed onto epoxy resin discs (O= 10 mm; thickness= 2.5 mm) and the bonded sets were subjected to step-stress fatigue tests (initial load: 200 N; step-size: 50 N; 10,000 cycles per step; 20 Hz). Fatigue data were analyzed using Kaplan-Meier and Weibull statistical analyses. Fractography and topography analyses were also conducted. The fatigue findings demonstrated that the performance among groups for both baseline and aging conditions maintained a tendency: the CA groups had the worst behavior (baseline: 893 N/143,667 cycles; aging: 639 N/84,179 cycles), while the surface etching with HF (baseline: 1247 N/214,333 cycles; aging: 816.67 N/128,333 cycles) and HF+CA groups (baseline: 1290 N/222,333 cycles; aging: 900 N/145,000 cycles) had no statistically significant difference between them. The aging protocol reduced the performance of all groups. The groups with better fatigue performance (HF and HF+CA) did not have statistical differences regarding structural reliability (Weibull modulus). Most failures were radial cracks from the cementation interface, except for CA aging specimens, with 27% failing from debonding. The HF etching led to noteworthy surface topographical alterations. Micromechanical interlocking resulting from HF acid etching remained prevalent in the fatigue behavior. Thus, the silane-based coupling agent (Monobond N) does not need to be applied after HF etching in terms of fatigue behavior outcomes.

This study evaluated the effect of grinding and polishing the inner surface of monolithic discs made of zirconia polycrystals (ZR) and lithium disilicate glass-ceramic (LD) on the load-bearing capacity under fatigue of the restorations bonded onto a dentin analogue material (epoxy resin). ZR and LD ceramic discs (10 mm in diameter, 1 mm in thickness) were produced and randomly allocated into 10 groups considering the internal adjustment approach: Ctrl – No adjustment; F – Grinding with fine diamond bur (46 μm); F + Pol – Grinding with fine diamond bur followed by polishing with 2 tips (finisher and polisher); FF – Grinding with extrafine diamond bur (30 μm); FF + Pol – Grinding with extrafine diamond bur followed by polishing. In addition, discs (10 mm in diameter, 2.5 mm in thickness) of fiber reinforced epoxy resin were produced. Afterwards, the intaglio surface of the ZR discs were air-abraded with 45 μm alumina particles for 10 s, the LD and resin epoxy discs were etched with hydrofluoric acid (5%/20 s and 10%/60 s, respectively), and the treated discs were primed as recommended. Each ceramic disc was luted onto the epoxy resin disc with resin cement. Then, the samples were tested under a step-stress fatigue test (20 Hz, 10,000 cycles/step, step-size of 100 N starting at 200 N, and proceeding until failure detection). Fractographic, topographic and surface roughness analysis were also performed. The adjustments (grinding with or without polishing) (ZR: 733–880 N; LD: 1040–1106 N) triggered a detrimental effect on the fatigue behavior in both ceramics compared with the absence of treatment (control group; ZR: 973 N; LD: 1406 N). The polishing step had no effect on fatigue findings. Thus, grinding the inner surface of the tested ceramics should be avoided wherever possible to prevent introducing damage and its detrimental effects on the fatigue behavior.

To evaluate the fatigue failure load (FFL), cycles for fatigue failure (CFF) and survival rates of different occlusal thicknesses of resin composite simplified crowns with internal adjustments (IA) or without as control (C).30 monolithic simplified crowns of CAD/CAM resin composite (Tetric CAD, Ivoclar) were milled in three different occlusal thicknesses (0.5 mm, 1.0 mm, and 1.5 mm). Half of the crowns were submitted to restricted adjustment with diamond burs on the crown's inner surface and half remained milled without internal adjustment. The samples were treated and adhesively luted onto a prosthetic preparation made of epoxy resin reinforced by glass-fiber substrate. The sets were subjected to a fatigue test (cyclic fatigue: initial load of 200 N; step-size of 50 N; 10,000 cycles/step; 20 Hz; maximum load: 2800 N).Microscopic analysis of tested representative samples was performed. The fatigue data were statistically analyzed (α= 0.05) and the micrograpic images were qualitatively evaluated.All specimens from groups 1.0C and 1.5C survived the cyclic loads, while all 0.5C samples failed during the test. The 1.0IA and 1.5IA crowns showed no statistical difference for FFL (2530 N= 2670 N) and CFF (471,000 cycles= 499,000 cycles) between them, and they were both statistically superior to the 0.5IA (FFL= 1812.50 N; CFF= 327,500 cycles). The 1.0 mm and 1.5 mm crowns presented superior fatigue behavior (2530 N-2800 N) compared to the 0.5 mm crowns (1812 N-2140 N), whether internal adjustment was performed or not. A statistically significant difference was found for FFL and CFF of 0.5 mm crowns with and without internal adjustment, with a deleterious impact of the adjustment for both parameters (FFL and CFF: 0.5C 0.5IA).Resin composite milled crowns can bear high cyclic fatigue loads despite thickness, although thicker crowns had better mechanical behavior; however, the internal adjustment in the composite resin crown leads to a detrimental effect on its fatigue behavior, which presents a risk of mechanical failure due to premature fatigue.

This study evaluated the influence of the piston material (glass fiber-reinforced epoxy resin or stainless steel) and the piston tip diameter (6 or 40 mm) on the fatigue mechanical behavior, failure mode, and stress distribution of feldspathic ceramic simplified restorations. Pistons were machined in glass fiber-reinforced epoxy resin (ER) and in stainless steel (SS), with active tips simulating the curvature radius of 6- or 40-mm diameter spheres. A total of sixty (N= 60) feldspathic ceramic discs (Ø= 10 mm; thickness= 1.0 mm) were adhesively luted onto supporting substrate discs (Ø= 10 mm; thickness= 2.5 mm) and allocated into 4 groups (n= 15) according to the piston used for fatigue testing: ER_6, ER_40, SS_6, SS_40. Afterwards, the specimens were submitted to the cyclic fatigue test (20 Hz frequency; initial load= 100 N; step= 50 N; 10,000 cycles/step, upon specimen failure detection). The collected data were analyzed by two-way ANOVA (α= 0.05) to verify differences by considering 'piston material' and 'piston diameter' as factors, and their association. In addition, a survival analysis (Kaplan Meier with Mantel-Cox log-rank post-hoc tests) was conducted (α= 0.05). Fractographic and finite element (FEA) analyzes were also performed. 'Piston material' (p= 0.040, F= 4.43) and 'piston diameter' (p 0.000, F= 563.21) had a significant influence on the fatigue failure load (FFL) and the number of cycles for failure (CFF) values. Feldspathic restorations showed higher FFL and CFF (p 0.05) when tested with a 40 mm diameter piston compared to a 6 mm diameter piston (ER_40 and SS_40 ER_6 SS_6). In relation to the piston material, ER and SS pistons with 40 mm diameter promoted similar fatigue performance (ER_40: 946.67 N/179,333 cycles = SS_40: 936.67 N/177,333 cycles), while 6 mm diameter groups presented different fatigue performance (ER_6: 440 N; 78,000 cycles SS_6: 353.3 N; 60,667 cycles). Hertzian cone crack failures were only observed in the groups tested with 6 mm pistons, regardless of piston material. Higher stress concentration on the ceramic surface was observed when using 6 mm diameter pistons, whereas the SS_6 group showed a slight increase in stress concentration in comparison to the ER_6 group. The piston diameter showed an influence on the fatigue behavior, failure mode, and stress distribution of feldspathic ceramic simplified restorations. However, the influence of piston material is only observed when 6 mm diameter pistons are used. The 40 mm diameter pistons led to radial crack, being more appropriate for fatigue test of simplified feldspathic ceramic restorations with a thickness ≤ 1 mm. Whilst the 6 mm diameter pistons should be avoided, once tend to induce Hertzian cone crack failures and to underestimate fatigue performance.

Made available in DSpace on 2022-04-28T19:49:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Objectives: To modify the surface of denture base material by coating it with cinnamon-laden nanofibers to reduce Candida albicans (C. albicans) adhesion and/or proliferation. Materials and methods: Heat-cured poly(methyl methacrylate) (PMMA) specimens were processed and coated, or not, with cinnamon-laden polymeric nanofibers (20 or 40 wt.% of cinnamon relative to the total polymer weight). Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) analyses of the nanofibers were performed. Antifungal activity was assessed through agar diffusion and colony-forming unit (CFU/mL) assays. Representative SEM morphological analysis was carried out to observe the presence/absence of C. albicans on the fibers. Alamar blue assay was used to determine cell toxicity. Analysis of variance and the Tukey’s test were used to analyze the data (α = 0.05). Results: SEM imaging revealed nanofibers with adequate (i.e., bead-free) morphological characteristics and uniform microstructure. FTIR confirmed cinnamon incorporation. The cinnamon-laden nanofibers led to growth inhibition of C. albicans. Viable fungal counts support a significant reduction on CFU/mL also directly related to cinnamon concentration (40 wt.%: mean log 6.17 CFU/mL < 20 wt.%: mean log 7.12 CFU/mL), which agrees with the SEM images. Cinnamon-laden nanofibers at 40 wt.% led to increased cell death. Conclusions: The deposition of 20 wt.% cinnamon-laden nanofibers onto PMMA surfaces led to a significant reduction of the adhesive and/or proliferative ability of C. albicans, while maintaining epithelial cells’ viability. Clinical relevance: The high recurrence rates of denture stomatitis are associated with patient non-adherence to treatments and contaminated prostheses use. Here, we provide the non-patients’ cooperation sensible method, which possesses antifungal action, hence improving treatment effectiveness. Department of Cariology Restorative Sciences and Endodontics University of Michigan School of Dentistry, 1011 N. University (Room 5223) Department of Restorative Dentistry School of Dentistry Federal University of Pelotas, RS Department of Physiology and Pathology University Estadual Paulista – UNESP, SP Post-Graduate Program in Oral Science Faculty of Dentistry Federal University of Santa Maria (UFSM), Rio Grande Do Sul State Department of Periodontics and Oral Medicine University of Michigan School of Dentistry Department of Physiology and Pathology University Estadual Paulista – UNESP, SP

OBJECTIVE: This study aimed to analyze the reporting and conduct characteristics of systematic reviews (SRs) published in dentistry by Brazilian corresponding authors and compare reporting characteristics of Brazilian SRs with the rest of the world. METHODS: A search in PubMed was performed to identify SRs published in dentistry in 2017 assessing different aspects of oral heath irrespective of the design of included studies. From this dataset, a subgroup analysis was performed considering only SRs published by Brazilian corresponding authors. Study screening was performed by two researchers independently, while for data extraction, one of three reviewers extracted details related to reporting and conduct of SRs. The completeness of reporting of 24 characteristics, included in the PRISMA Statement of the SRs classified as treatment/therapeutic, was evaluated comparing Brazilian SR to SRs from all other countries. RESULTS: We included 117 SRs with Brazilian corresponding authors. The majority focused on dental treatments (39.3%), with oral surgery (n=19, 16.2%) as the most commonly published. Included SRs presented varying reporting/conduct characteristics. Items such as use of reporting guidelines and screening method used were well reported. However, most SRs did not assess the risk of publication bias and did not use the GRADE assessment. Four (of 24) reporting characteristics of Brazilian SRs compared to SRs from the rest of world were reported statistically significantly more frequently: mention of a SR protocol, trial registry searched, screening method reported, and assessment of risk of bias/quality of studies. CONCLUSION: Reporting and conduct characteristics of Brazilian SRs are highly variable.

This study assessed the fatigue performance (biaxial flexure fatigue strength), surface characteristics (topography and roughness) and structural stability (t-m phase transformation) of a Y-TZP ceramic subjected to air-abrasion using new powders (7% and 20% silica-coated aluminum oxide particles) in comparison to commercially available powders. Disc-shaped specimens were manufactured (ISO 6872–2015) and randomly allocated into four groups considering the air-abrasion materials: SiC: commercially available silica-coated aluminum oxide; AlOx: commercially available aluminum oxide; 7%Si and 20%Si: experimentally produced materials consisting of 7% and 20% silica-coated AlOx, respectively. Air-abrasion was executed by a blinded researcher (1 cm distance from the tip to the specimen surface, under 2.8 bar pressure for 10 s). The fatigue tests (n = 15) were performed by the staircase method under a piston-on-three-balls assembly. Topography and roughness assessments (n = 30) of abraded samples and fractography of failed discs were performed. The highest fatigue strength (MPa) was observed for 7%Si (887.20 ± 50.54) and SiC (878.16 ± 29.81), while the lowest fatigue strength for 20%Si (773.89 ± 46.44) and AlOx (796.70 ± 46.48). Topography analysis depicted similar surface morphology for all conditions. However, roughness (μm) was only statistically different between 7%Si (Ra = 0.30 ± 0.09; Rz = 2.31 ± 0.63) and SiC (Ra = 0.26 ± 0.04; Rz = 1.99 ± 0.34). Monoclinic phase grains appeared on Y-TZP surface in a similar content (≈11–12%) for the protocols. Fractography showed all failures starting on air-abraded surface/sub-surface defects from the tensile side. In terms of roughness, phase transformation and fatigue, the new 7% silica-coated aluminum oxide presented similar behavior to the commercially available powder. Increasing silica-coating concentration to 20% did not lead to a gentle air-abrasion protocol.

Purpose To evaluate the substrate masking ability of different ceramic systems used for complete crowns and assess the influence of their association with an opaque resin-based luting agent (OLA). Methods Eleven ceramic groups were tested (n = 10). Bilayer groups were: ZrPc — zirconia + porcelain; CAD-onHT — zirconia + high translucent lithium disilitace; CAD-onLT — zirconia + low translucent lithium disilicate; LDPc — high opaque lithium disilicate + porcelain. Monolithic groups were: TZ — high translucent zirconia; TLS — translucent, zirconia-reinforced lithium silicate; HTLS — high translucent, zirconia-reinforced lithium silicate; LTLD — low translucent lithium disilicate; HTLD — high translucent lithium disilitace; LGC — leucite-reinforced glass ceramic; FC — feldsphatic ceramic. The substrates adopted were resin composites shaded A1 (control), A3.5 and C4; coppery and silvery metals. Color differences (ΔE00) and translucency parameter (TP00) were assessed with the CIEDE2000 formula. ΔE00 was obtained assessing the ceramic influence only and in association with OLA. Results Zirconia groups presented lower ΔE00 and TP00. CAD-on structures associated to OLA led to the lower ΔE00 when tested over metals. ΔE00 for LDPc were similar to zirconia when associated to OLA. Monolithic groups presented significant higher ΔE00 and TP00 compared to bilayers, with ΔE00 below the acceptability threshold only when associated to OLA over substrate shade A3.5. Conclusions Ceramic type and the white-opaque resin-based luting agent presented a significant effect on the substrate masking ability. All the discolored substrates tested are adequately masked with veneered zirconia or with LDPc (preferably associated to OLA). The CAD-on technique associated with OLA improved the masking ability over metallic substrates.

To evaluate the fatigue failure load (FFL), number of cycles for failure (CFF) and survival probabilities of lithium-disilicate (LD) monolithic crowns manufactured by two processing techniques (pressing vs. CAD/CAM) adhesively cemented to a dentin-analogue material, considering two surface treatments (conventional vs. simplified). Surface characteristics (topography, roughness and fractal dimensions) were also assessed. Forty (40) monolithic crowns were manufactured considering two specific processing techniques for each ceramic system: LDCAD – CAD/CAM lithium-disilicate (IPS e.max CAD, Ivoclar Vivadent); LDPRESS – pressed lithium-disilicate (IPS e.max Press, Ivoclar Vivadent). The crowns were adhesively cemented (Multilink Automix System, Ivoclar Vivadent) onto dentin analogue preparations considering two distinct protocols of surface treatments (conventional – hydrofluoric acid etching + silane application [HF+Sil] or simplified – etching with one-step primer (Monobond Etch&Prime, Ivoclar Vivadent) [EP]). The cemented assembly was stored in distilled water at 37 °C for 3 days and fatigue tests were run (step-stress approach: load ranging from 400 to 2000 N, step-size of 100 N, 15,000 cycles/step, 20 Hz). Fractography, surface topography, roughness, and fractal dimension analyses were performed. LDPRESS[EP] group depicted higher FFL, CFF and survival probabilities in comparison to LDCAD groups, regardless of the conditioning method. A tendency of higher Weibull modulus (mechanical reliability) was observed when using [EP] for both LDPRESS and LDCAD. SEM and AFM analysis showed very distinct initial surface patterns for the distinct processing techniques considered (LDCAD with higher fractal dimension and lower roughness than LDPRESS), and both surface treatments distinctly affected these surface characteristics. All failures were radial cracks originating at the ceramic-cement interface. Pressed lithium-disilicate monolithic crowns showed better fatigue performance in comparison to CAD/CAM milled crowns, especially when they were treated with self-etching ceramic primer. The surface treatment with self-etching primer led to similar fatigue performance when compared to hydrofluoric acid plus silane application for the same processing technique, but it tended to provide higher mechanical reliability.

This study aimed to evaluate the effects of various polishing systems associated or not to finishing with diamond burs of lower-grit size on the topography, roughness, and fatigue behavior of a ground yttrium-stabilized tetragonal polycrystalline zirconia (Y-TZP). Disc specimens of Y-TZP (Zenostar T, Ivoclar-Vivadent) were produced (diameter = 15 mm, thickness = 1.2 ± 0.2 mm; ISO 6872-2015) and randomly allocated into 8 groups: [Ctrl] as-sintered; [Gr] ground with coarse diamond bur; [Gr+Eve] grinding + polishing with EveDiacera (2-step polishing system); [Gr+Fin+Eve] grinding + finishing + polishing with EveDiacera; [Gr+Kg] grinding + polishing with Kg Viking (2-step polishing system); [Gr+Fin+Kg] grinding + finishing + polishing with Kg Viking; [Gr+Op] grinding + polishing with Optrafine (3-step polishing system); and [Gr+Fin+Op] grinding + finishing + polishing with Optrafine. Next, surface topography, roughness, phase transformation, fatigue strength (staircase method), and fractography analyses were performed. Grinding changed the surface topography and generated higher roughness (Ra in μm) (1.214); the subsequent finishing/polishing procedures were able to reduce the roughness (0.326–0.839); however, it remained higher than the control [ctrl] group (0.221). All samples subjected to surface treatment presented an increase in m-phase content (8.04–17.46%). In terms of fatigue strength (in MPa), the grinding group (677.36) and polishing/finishing groups (641.66–707.20) presented higher fatigue strength than the control [ctrl] group (592.48). Finishing before polishing had no effect on fatigue strength (645.37–707.20). Grinding altered the Y-TZP surface features and increased their fatigue strength by phase transformation mechanism, while the finishing/polishing procedures promoted surface smoothening, while maintaining high fatigue strengths. Finishing as an additional step before polishing had no effect on roughness reduction and fatigue strength improvements; thus, the finishing procedure might be unnecessary.

Objective: To evaluate the fatigue failure load, number of cycles until failure, and survival probability of adhesively cemented materials with different microstructures (glass-, hybrid- and resin-ceramic) used to manufacture CAD/CAM monolithic restorations. Methods: Disc-shaped specimens (n = 15; Ø = 10 mm; thickness = 1.0 mm) were produced from CAD/CAM blocks as follows: feldspathic (FEL); leucite (LEU); lithium disilicate (LD); zirconia-reinforced lithium silicate (ZRLS); polymer-infiltrated ceramic network (PICN); and resin nanoceramic (RNC). Adhesive cementation was performed onto epoxy discs (dentin analogue- Ø = 10 mm; thickness = 2.5 mm). The cemented assemblies were subjected to fatigue testing using a step–stress approach (400 N–2200 N; step-size of 200 N; 10,000 cycles per step; 1.4 Hz). Fatigue data were analyzed using Kaplan–Meier and Mantel–Cox (log-rank) tests (p < 0.05) and Weibull statistical analysis. Fractographic analysis was also performed. Results: All RNC specimens survived the fatigue test (100% probability of survival at 2200 N; 100,000 cycles) and presented occlusal deformation in response to loading, while all other tested materials failed in distinct loading steps with radial cracks starting from the bonding surface. LD (1146.7 N; 47,333) and ZRLS (1013.3 N; 40,666) materials obtained the highest fatigue failure loads and cycles until failure, meanwhile all PICN specimens failed during the first step (0% probability of survival at 400 N; 10,000). FEL had similar Weibull modulus to LD and ZRLS and higher than LEU for both load and number of cycles outcomes. Significance: The microstructure of adhesively cemented glass-, hybrid- and resin-ceramic CAD/CAM restorative materials influence their response during fatigue testing, which aids in suggesting the best clinical indications.

Made available in DSpace on 2019-10-06T16:12:48Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-03-01 The aim of this study was to evaluate the effect of sequential usage (milling order) of CAD/CAM diamond burs on the surface roughness, topography and fatigue performance of a lithium disilicate glass-ceramic. Seventy-two (72) ceramic discs (Ø= 13.5 mm; thickness= 1.2 mm; IPS e.max CAD) were milled using four pairs of burs and allocated into three groups (n = 24) according to the milling sequence: 1 through 6 (1−6), 7 through 12 (7−12), and 13 through 18 (13−18). The burs were evaluated under SEM at the different milling stages to depict any degradation generated by the milling sequence. Fatigue performance was assessed by a stepwise approach (initial strength of 20 MPa for 5000 cycles; incremental steps of 20 MPa for 20,000 cycles each until fracture; frequency of 20 Hz) using the ISO 6872:2015 recommendation for piston-on-three-balls biaxial flexure strength tests. Surface roughness, topography analysis and fractography of the failed discs were also performed. Survival analysis (Kaplan-Meier and Mantel-Cox post hoc test) showed that the milling sequence had no effect on the fatigue strength (190 – 201 MPa) or the number of cycles until fracture (174,958 – 180,087 cycles). Ceramic topography and roughness (Ra, Rz and RSm parameters) were similar among the groups, even though SEM analysis depicted CAD/CAM diamond burs degraded over time. Fractography evidenced all failures starting from surface defects introduced by milling at the samples’ tensile side. The sequential usage of CAD/CAM diamond burs (milling order) does not affect the lithium disilicate surface roughness, topography or fatigue performance. MSciD and PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Unit) São Paulo State University (Unesp) Institute of Science and Technology, São José dos Campos MSciD and PhD Post-Graduate Program in Oral Science (Prosthodontics Units) Faculty of Dentistry Federal University of Santa Maria (UFSM) MSciD Graduate Program in Dentistry Meridional Faculty-IMED MSciD and PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Unit) São Paulo State University (Unesp) Institute of Science and Technology, São José dos Campos

This study evaluated the fatigue failure load, number of cycles for failure and survival probability of 2nd and 3rd generation yttrium-stabilized zirconia (YSZ) adhesively cemented to a dentin analogue substrate. Disc-shaped specimens (n = 10; O = 10 mm; thickness = 1.0 mm) were produced from four 2nd generation YSZs (Lava Plus, 3M ESPE; Vita In-Ceram YZ-HT, VITA Zahnfabrik; Zirlux FC, Ivoclar Vivadent; Katana ML-HT, Kuraray) and two 3rd generation YSZs (Katana UTML and Katana STML, Kuraray). Each YSZ disc was adhesively cemented (Multilink Automix System) onto its dentin analogue pair (epoxy resin, O = 10 mm; thickness = 2.5 mm). Fatigue tests were conducted through step-stress approach (load ranging from 400 to 2600 N; step-size of 200 N; 20,000 cycles per step, 20 Hz) and the obtained data were analyzed using Kaplan Meier and Mantel-Cox tests. Surface topography and phase transformation (m-, t-, and c-phases) inspections after particle air-abrasion of the YSZs were performed, as well as fractographic analysis of the failed specimens. Second-generation zirconia materials presented higher fatigue failure load, number of cycles for failure, and survival probability than 3rd generation. Similar topographical characteristics of the YSZs could be noted. Phase transformation (t- to m-phase) after YSZ air-abrasion was only observed for 2nd generation materials. All failures started from the surface/sub-surface defects located at the cementation interface. 2nd generation zirconia presented higher load-bearing capacity under cyclic loading than 3rd generation materials.

The purpose of this study was to investigate whether different surface treatments, executed before and after the sintering process, affect the surface characteristics (roughness and morphology) and shear bond strength of computer-aided design–computer-aided manufacturing (CAD–CAM) milled zirconia luted with self-adhesive resin cement onto human dentin. Sixty-four rectangular zirconia slabs (6 × 8.5 × 2.3 mm thickness) were prepared using the CAD–CAM system and randomly distributed into two groups according to the moment of treatment, before and after sintering, and four subgroups according to the surface treatment (n = 8): C (untreated; control), AO (aluminum oxide air abrasion), GB (glass beads air abrasion), and HA (etching with hydrofluoric acid). The samples were evaluated using a confocal laser microscope to assess the surface roughness and morphology. For the shear bond strength test, the milled zirconia was cemented onto dentin slabs using self-adhesive resin cement and submitted to the test in a universal testing machine. Data were submitted to a two-way ANOVA and Tukey test (p

To evaluate the effect of different etching times of a self-etching ceramic primer on the microshear bond strength (µSBS) and topographic surface pattern of a lithium-disilicate glass-ceramic.Ceramic slices were subjected to an in-lab simulation of CAD/CAM milling and randomly allocated to 10 groups (n = 35) considering two factors: "surface treatment" in 5 levels - one control group (5% hydrofluoric acid + silane application [HF5+SIL]), and 4 experimental groups using ceramic etching/primer (Monobond EtchPrime, EP) with different passive application times (40 s, 2 min, 5 min, or 10 min); and "aging" factor in 2 levels - short-term (after 24 h), or long-term (storage for 180 days + 12,000 thermal cycles). Composite cement cylinders were built and µSBS tests were run in a universal testing machine. The failure patterns were categorized, and complementary analyses with SEM and Atomic Force Microscopy (AFM) were performed.The groups showed statistically similar bond strengths in the short term (range 22.4 to 25. 1 MPa). However, only the EP 20s+40s (19. 3 MPa) and EP 20s+5min (21.5 MPa) groups maintained stable bond strength in the long term, and HF5+SIL (17. 1 MPa) presented statistically significantly lower values than did EP 20s+5min. The failure pattern was predominantly adhesive. The increased application time of the ceramic primer promoted greater dissolution of the glass matrix; thus, the EP 20s+10min group presented the most complex surface characteristics in the fractal dimension analysis.The self-etching ceramic primer can be used as an alternative to classical conditioning with HF plus silane, promoting stable bond strength for etching times of 40 s or 5 min of passive application.

The aim of this study was to characterize the flexural strength and elastic modulus of CAD/CAM resin composite material and to evaluate the influence of different surface treatments and storage conditions on the fatigue behavior of bonded composite crowns. Bars (flexural strength, n= 30; elastic modulus, n= 5) (1.2 × 4 × 12 mm) were produced for three-point bending test and CAD/CAM milled crowns (n= 5) (thickness= 1 mm) adhesively cemented to an epoxy resin substrate for fatigue tests. Bars and crowns were randomly allocated into two “surface treatments”: no surface treatment (CTRL) and air-abrasion with 110 μm Al2O3 particles (AlOx); while the crowns were also subdivided into “aging condition” (baseline - storage for 24 h to 7 days, and aging – storage for 150 days + 25,000 thermal cycles). The three-point bending test was performed according to ISO 6872 and the luted crowns were subjected to step-stress fatigue test (initial load of 200 N; step-size of 50 N; 10,000 cycles per step; 20 Hz). Complementary analysis by Stereomicroscopy and Field Emission Scanning Electron Microscopy (FE-SEM) were performed. The flexural strength and fatigue data were submitted to statistical tests (α= 0.05). The results showed that air-abrasion reduces the flexural strength and the characteristic strength of the resin composite, without modifying its elastic modulus or its structural reliability (Weibull Modulus). Air-abrasion did not influence the fatigue behavior of the cemented crowns. Notwithstanding, a decrease in the survival rate was observed after 445,000 cycles (2,400 N) when subjected to aging at both the CTRL or AlOx conditions. FE-SEM micrographs of the crowns showed that alumina particle air-abrasion treatment can modify the topography of its treated inner surface. Therefore, air-abrasion with alumina powder introduces defects onto the surface of the CAD/CAM resin composite material, decreasing the flexural strength, but without changing its elastic modulus and reliability. Adhesive cementation onto an epoxy resin substrate prevented an influence of the introduced defects on the fatigue performance of the resin composite restoration. Nevertheless, the fatigue behavior may be damaged by aging regimen.

This study evaluated the effect of distinct surface treatments on the fatigue behavior (biaxial flexural fatigue testing) and surface characteristics (topography and roughness) of a 5% mol yttria partially stabilized zirconia ceramic (5Y-PSZ). Disc-shaped specimens of 5Y-PSZ (IPS e.max ZirCAD MT Multi) were manufactured (ISO 6872–2015) and allocated into six groups (n = 15) considering the following surface treatments: Ctrl – no-treatment; GLZ – low-fusing porcelain glaze application; SNF – 5 nm SiO2 nanofilm; AlOx – aluminum oxide particle air-abrasion; SiC – silica-coated aluminum oxide particles (silica-coating); and 7%Si – 7% silica-coated aluminum oxide particles (silica-coating). The biaxial flexural fatigue tests were performed by the step-stress method (20Hz for 10,000 cycles) with a step increment of 50N starting at 100N and proceeding until failure detection. The samples were tested with the treated surface facing down (tensile stress side). Topography, fractography, roughness, and phase content assessments of treated specimens were performed. GLZ group presented the highest fatigue behavior, while AlOx presented the lowest performance, and was only similar to SiC and 7%Si. Ctrl and SNF presented intermediary fatigue behavior, and were also similar to SiC and 7%Si. GLZ promoted a rougher surface, Ctrl and SNF had the lowest roughness, while the air-abrasion groups presented intermediary roughness. No m-phase content was detected (only t and c phases were detected). In conclusion, the application of a thin-layer of low-fusing porcelain glaze, the deposition of silica nanofilms and the air-abrasion with silica-coated alumina particles had no detrimental effect on the fatigue behavior of the 5Y-PSZ, while the air-abrasion with alumina particles damaged the fatigue outcomes.

Purpose This study evaluated the influence of different surface treatments of zirconia used to enhance bonding with veneering porcelain, and thermocycling on the resistance to porcelain cracking and delamination during fatigue test. Methods Bilayer ceramic discs were made from zirconia blocks (IPS e.max Zircad MO, Ivoclar Vivadent - 0.7 mm thickness) and randomized into 8 groups (n= 15) according to two factors: 'zirconia surface treatment' (Control; Grinding - diamond bur; Air-abrasion - aluminum oxide particles; and Liner - application of a ceramic liner [IPS e.max Zirliner, Ivoclar Vivadent]); and 'thermocycling' (presence - 12,000 thermal cycles; 5-55oC; or absence). The discs were veneered with porcelain (IPS e.max Ceram, Ivoclar Vivadent - 0.7 mm; totaling 1.4 mm thickness) according to ISO 6872:2015 for biaxial flexure strength testing. Fatigue tests (step-stress approach; 20 to 100 MPa; step of 10 MPa; 10,000 cycles per step; 10 Hz frequency) were run, followed by the data analysis (Kaplan-Meier and Mantel-Cox post-hoc tests). Analysis of roughness, topography, crystallographic phase arranges and fractography were also executed. Results The surface treatment and thermocycling did not influence the porcelain crack nor delamination resistance. When only comparing the surface treatments for crack resistance outcome, the liner application depicted the worst fatigue performance in comparison to grinding and air-abrasion, while all groups were similar for delamination. Conclusions Neither the surface treatment of the zirconia nor the thermocycling influences the porcelain crack resistance or the resistance to delamination of the bilayer porcelain-veneered zirconia specimens.

Statement of problem Severely discolored substrates have been shown to limit the use of computer-aided design and computer-aided manufacturing (CAD-CAM) ceramic blocks because they provide insufficient color masking. Purpose The purpose of the in vitro study was to evaluate the effect of a layer of high-value opaque composite resin over discolored substrates to determine its masking ability with CAD-CAM ceramics. Material and methods Six ceramic groups (n=10) were tested. A bilayer group of zirconia and porcelain served as the control. The CAD-CAM monolithic groups were translucent zirconia, zirconia-reinforced lithium silicate, lithium disilicate, leucite-reinforced glass-ceramic, and feldspathic ceramic. Five substrates were used: A1 (used as reference), A3.5, C4, and coppery and silvery metals. The substrates were separated as nonlayered or layered (with flowable or restorative opaque composite resins). The tested luting agents were white, opaque, and A1. Color differences (ΔE00) were assessed with the CIEDE2000 formula. A 2-way ANOVA (α=.05) was used to detect significant differences in ΔE00 among the groups for each substrate. The results were compared with acceptability (1.77) and perceptibility (0.81) thresholds. Results The flowable composite resin layer associated with A1 luting agent ensured ΔE00 lesser the than perceptibility thresholdwith the use of CAD-CAM monolithic ceramics, with the lowest values for zirconia-reinforced lithium silicate in substrates A3.5 (0.53) and C4 (0.32) and for leucite-reinforced glass-ceramic for coppery (0.49) and silvery (0.81) substrates (P Conclusions The application of a flowable opaque composite resin and the use of a shaded luting agent ensure masking with CAD-CAM monolithic ceramics.

The aim of the present scoping review was to identify and discuss the methods, testing parameters, and characteristics used to induce cyclic fatigue on non-anatomic dental ceramic specimens. In vitro studies written in English which evaluated commercially-available non-anatomic dental ceramic specimens subjected to mechanical cyclic fatigue were selected. The search was performed in the PubMed, Scopus and Web of Science databases. The initial search yielded 1,636 articles, of which 81 were included. Based on the collected data, most of the included studies evaluated dental ceramic specimens cemented to supporting substrate (n = 42; 51.9%); used step-stress (n = 35; 42.2%) accelerated fatigue test, loading frequencies above 10 Hz (n = 31, 35.6%), stainless steel (n = 28, 32.6%) load applicator with spherical shaped tip 40 mm diameter (n = 25, 30.9%); applied only axial loads (n = 77, 95.1%); and considered a wet testing environment (n = 65, 78.3%). The definition of test geometry, method, and testing parameters must be cautiously considered according to the study objective and the scenario that is simulated. Accelerated fatigue tests, load frequencies up to 20 Hz, a 40 mm stainless steel spherical load applicator and a wet testing environment are the major common defined parameters presented in the existing literature. More studies exploring the influence of such factors on fatigue mechanism are necessary.

Made available in DSpace on 2021-06-25T10:53:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-05-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul This study evaluated the influence of distinct substrates on the mechanical fatigue behavior of adhesively cemented simplified restorations made of glass, polycrystalline or polymer infiltrated-ceramics. CAD/CAM ceramic blocks (feldspathic – FEL; lithium disilicate – LD; yttria-stabilized zirconia – YZ; and polymer-infiltrated ceramic network – PICN) were shaped into discs (n = 15, Ø = 10 mm; thickness = 1.0 mm), mimicking a simplified monolithic restoration. After, they were adhesively cemented onto different foundation substrates (epoxy resin – ER; or Ni–Cr metal alloy – MA) of the same shape (Ø = 10 mm; thickness = 2.0 mm). The assemblies were subjected to fatigue testing using a step-stress approach (200N-2800 N; step-size of 200 N; 10,000 cycles per step; 20 Hz) upon the occurrence of a radial crack or fracture. The data was submitted to two-way ANOVA (α = 0.05) to analyze differences considering ‘ceramic material’ and ‘type of substrate’ as factors. In addition, a survival analysis (Kaplan Meier with Mantel-Cox log-rank post-hoc tests; α = 0.05) was conducted to obtain the survival probability during the steps in the fatigue test. Fractographic and finite element (FEA) analyzes were also conducted. The factors ‘ceramic material’, ‘type of substrate’ and the interaction between both were verified to be statistically significant (p < .001). All evaluated ceramics presented higher fatigue failure load (FFL), cycles for failure (CFF) and survival probabilities when cemented to the metallic alloy substrate. Among the restorative materials, YZ and LD restorations presented the best fatigue behavior when adhesively cemented onto the metallic alloy substrate, while FEL obtained the lowest FFL and CFF for both substrates. The LD, PICN and YZ restorations showed similar fatigue performance considering the epoxy resin substrate. A more rigid foundation substrate improves the fatigue performance of adhesively cemented glass, polycrystalline and polymer infiltrated-ceramic simplified restorations. PhD Post-Graduate Program in Oral Science (Prosthodontic Unit) Faculty of Odontology Federal University of Santa Maria Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos Department of Dental Materials Science Academic Centre for Dentistry Amsterdam (ACTA) Universiteit van Amsterdam and Vrije Universiteit Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos CAPES: 001 Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul: 18/2551-0000520-7

Purpose To evaluate the influence of quantity and positioning of veneered zirconia specimens during firing of porcelain on their fatigue performance and colorimetric differences. Methods Bilayer discs (O=15 mm) were made, following ISO 6872 guidelines, using a Y-TZP core (yttria-stabilized tetragonal zirconia polycrystal ceramic; VITA In-Ceram YZ) and a feldspathic veneering material (VITA VM9), being both layers with 0.7 mm thickness. Y-TZP discs were sintered, the veneering material was applied over it, and the bilayer specimens were fired according to two factors (n=20): 'quantity' (1 or 5 samples per firing cycle; G1 and G5 groups respectively) and 'positioning' of the specimens inside the furnace (center or periphery of the refractory tray; G5C and G5P groups, respectively). The CIEL*a*b* parameters were recorded with a spectrophotometer and the color difference (ΔE 00 ) and translucency (TP 00 ) were calculated using CIEDE2000 equations. The step-stress fatigue test was performed with the veneer facing down (region of tensile stress concentration), 10 Hz frequency, initial tension of 20 MPa for 5,000 cycles, followed by steps of 10,000 cycles using a step size of 10 MPa, up to 100 MPa; data from strength and number of cycles for failure were recorded for statistical analysis. Results Unacceptable color differences (ΔE 00 >1.8) were observed comparing G5C vs. G1 (quantity) and G5C vs. G5P (positioning), meanwhile translucency parameters were not affected. Besides, only the 'quantity' factor influenced the fatigue performance (G1>G5C). None of the tested specimens survived beyond 90N and/or 75000 cycles. Conclusions The quantity and position of the specimens during firing influence the final color of porcelain-veneered zirconia, and firing one specimen per cycle improved the fatigue performance of the bilayer system.

This scoping review study aimed to map the evidence about solvents' use for gutta-percha dissolution and removal during endodontic retreatments. The study protocol followed the Joanna Briggs Institute guidelines, available online (https://osf.io/5vy8n/). Reporting was based on PRISMA Extension for Scoping Reviews. We selected dentistry studies that considered the effectiveness of solvents in gutta-percha dissolution in endodontic retreatments and compared their performance to the use of instrumentation techniques without solvents. The search and study screening were performed in PubMed and Scopus databases by two independent researchers. A descriptive analysis considered the study design, method/technique used for obturation, method/technique used for instrumentation during retreatment, solvent solutions tested, exposure time, and main findings. A total of 41 studies were included. Despite that, most studies suggested that solvents' use may complicate root canal cleanliness, regardless of the type of instrumentation used, and facilitate the presence of gutta-percha remnants in the root surface. Thus, the use of solvents should be avoided and its use should only be considered if the previous working length was not possible to access without it. Despite that, high heterogeneity was observed, further studies are still encouraged comparing the performance and effects of different solvents in different clinical scenarios.

Statement of problem The best protocol to restore endodontically treated teeth is still unclear, with many factors to be considered, including the selection and necessity of a post, the type of coronal restoration, the amount of remaining coronal structure, and the type of luting agent. Purpose The purpose of this systematic review was to assess the restorative preferences for endodontically treated teeth between dentists and dental students. Material and methods Survey studies, written in English, of dentists and dental students, which evaluated the use of intracanal posts and other restorative options for endodontically treated teeth, were selected. Searches were performed in the PubMed and SCOPUS databases without time restriction. Screening and data extraction were performed by 2 researchers independently. A standardized outline was used to extract the data (questions related to the theme and the response rate of each question on the survey), and the risk of bias was assessed. Descriptive analysis was performed of the collected information. Results Twenty-five articles were included. Most dentists who answered the surveys reported the time since graduation as 1 to 20 years (40%), and 44% were specialists. The most reported choices concerning the type of posts used were prefabricated posts (45.8%), cast metal posts (16.7%), and both posts (16.7%). The cast metal posts were cited more frequently in surveys published between 1994 and 2010, whereas prefabricated posts, both metal and glass fiber ones, were cited between 2006 and 2019. The preferred luting agent for intracanal posts was resin-based (47%). These choices seem to have been influenced by time and by the level of postgraduate training. Conclusions Restorative preferences related to posts have changed over time, from the use of cast posts to prefabricated ones or the use of both posts and seem to be influenced by experience and postgraduate training.

The aim of the study was to evaluate the effect of a ceramic primer and its increased passive application on the fatigue performance of adhesively cemented lithium disilicate simplified restorations. Ceramic discs (Ø = 10 mm; thickness = 1.0 mm) were submitted to an in-lab simulation of CAD/CAM milling and allocated into 8 groups (n = 15), considering 2 factors: “surface treatment”– PRIMER, only coupling agent application (Monobond N); HF5+PRIMER, 5% hydrofluoric acid and coupling agent; E&P 20s + 40s and E&P 20s+5min, ceramic etching/priming (Monobond Etch & Prime, E&P) for 20 s of active application followed by 40 s or 5 min of passive application, respectively; and “aging condition”– baseline, storage for 24 h to 5 days; aged, storage for 90 days +12,000 thermal cycles. Adhesive cementation (Multilink N) was performed onto epoxy discs (Ø = 10 mm; thickness = 2 mm) and the cemented assemblies were subjected to step-stress fatigue tests (initial load of 200 N; step-size of 50 N; 10,000 cycles per step; 20 Hz). The results showed that the groups had similar fatigue performance in the baseline condition (except for E&P 20s+5min: 940.0 N; 123,000 cycles > PRIMER: 786.7 N; 92,333 cycles). When aged, the PRIMER group presented the worst fatigue performance (480.8 N; 31,154 cycles) compared to the other groups (810.0–840.0 N; 97,000–103,000 cycles). In addition, only the PRIMER treatment showed unstable fatigue performance (baseline > aged). Therefore, ceramic surface treatment promoting micromechanical interlocking and chemical bonds is mandatory for stable fatigue performance of adhesively cemented lithium disilicate restorations. The one-step ceramic primer/conditioner promoted similar fatigue performance to the 5% hydrofluoric acid + coupling agent, but increased E&P etching time did not improve the fatigue behavior.

The aim of this study was to assess the stress/strain in dental implant/abutments with alternative materials, in implants with different microgeometry, through finite element analysis (FEA). Three-dimensional models were created to simulate the clinical situation of replacement of a maxillary central incisor with implants, in a type III bone, with a provisional single crown, loaded with 100 N in a perpendicular direction. The FEA parameters studied were: implant materials-titanium, porous titanium, titanium-zirconia, zirconia, reinforced fiberglass composite (RFC), and polyetheretherketone (PEEK); and abutment materials-titanium, zirconia, RFC, and PEEK; implant macrogeometry-tapered of trapezoidal threads (TTT) and cylindrical of triangular threads (CTT) (ø4.3 mm × 11 mm). Microstrain, von Mises, shear, and maximum and minimum principal stresses in the structures and in peri-implant bone were compared. There was increased stress and strain in peri-implant bone tissue caused by implants of materials with lower elastic modulus (mainly for PEEK and RFC). They also presented higher concentration of stresses in the implant itself (especially RFC). Zirconia implants led to lower stress and strains in peri-implant bone tissue. Less rigid abutments (RFC and PEEK) associated with titanium implants led to higher stress in the implant and in peri-implant bone tissue. The TTT macrogeometry showed a higher stress concentration in the implant and peri-implant bone tissue. The stress/strain in peri-implant bone tissue and implant structures were affected by the material used, where reduced values were caused by stiffer materials. Lower stress/strain values were obtained with cylindrical implants of triangular treads.

Background The aims of this study were to assess whether the previous registration of a systematic review (SR) is associated with the improvement of the quality of the report of SRs and whether SR registration reduced outcome reporting bias. Methods We performed a search in PubMed for SRs in dentistry indexed in 2017. Data related to SR registration and reporting characteristics were extracted. We analyzed if the reporting of 21 characteristics of included SRs was associated with the prospective registration of protocols or reporting of a previously established protocol. The association between prospective registering of protocols, reporting of funding and number of included studies versus outcome reporting bias was tested via multivariable logistic regression. Results We included 495 SRs. One hundred and 62 (32.7%) SRs reported registering the SR protocol or working from a previously established protocol. Thirteen reporting characteristics were described statistically significant in SRs registered versus SRs that were not. Publication bias assessment and Report the number of participants showed the highest effects favoring the register (RR 1.59, CI 95% 1.19–2.12; RR 1.58, CI 95% 1.31–1.92 respectively). Moreover, Registration was not significantly linked with the articles’ reporting statistical significance (OR 0.96, CI 95% 0.49–1.90). Conclusion There is a positive influence of previously registering a protocol in the final report quality of SRs in dentistry. However, we did not observe an association between protocol registration and reduction in outcome reporting bias.

Considering the long time spent in low frequency cyclic fatigue tests, this study aimed to evaluate the influence of loading frequency (2 Hz and 20 Hz) on the flexural fatigue strength (FFS) and on the time and number of cycles to failure of a leucite-reinforced glass-ceramic. Disc-shaped specimens were produced using leucite-reinforced glass-ceramic CAD/CAM blocks (IPS Empress CAD), according to ISO 6872/2015. Two fatigue tests were performed. The FFS (n = 17) was determined by staircase approach at a lifetime of 500,000 cycles, for 2 Hz (control - chewing frequency estimative) and 20 Hz (accelerated approach). To determine the time and the number of cycles to failure in flexural fatigue, discs (n = 20) were submitted to a cyclic loading ranging from 10 MPa to 99 MPa (60% of the monotonic strength), until a maximum of 500,000 cycles. Means, standard deviation and confidence intervals (CI) at 95% for FFS were calculated, whereas statistical differences were detected based on maximum likelihood estimations and overlapping of 95% CIs. Kaplan Meier (α = 0.05) and log rank post-hoc tests were used to analyze the time (in minutes) and the number of cycles to failure in the lifetime test. FFS did not differ significantly between 2 Hz (mean: 78 MPa; 95% CI: 69-88 MPa) and 20 Hz (mean: 84 MPa; 95% CI: 78-90 MPa). Regarding the lifetime test, there was no difference (p = 0.3) in the time to failure for 2 Hz (mean: 13 min; 95% CI: 6-20 min) and 20 Hz (mean: 69 min; 95% CI: 9-128 min). However, the group tested with 20 Hz survived a significantly (p 0.01) higher number of cycles (mean: 82,247 cycles; 95% CI: 11,450-153,044) than the group tested with 2 Hz (mean: 1588 cycles; 95% CI: 779-2397). Therefore, in leucite-reinforced glass-ceramic fatigue strength tests, limited to a lifetime of 500,000 cycles, the use of loading frequencies up to 20 Hz did not influence the FFS estimations when compared to 2 Hz (chewing frequency estimative), and may be an alternative to accelerate data collection in this type of mechanical test. However, in lifetime tests, the use of higher loading frequencies, as 20 Hz, did not save time, since a higher number of cycles was necessary to promote the failure, when compared to 2 Hz.

Nowadays, the concept of achieving high adhesion between restorative materials and tooth substrate and its importance on the longevity and reinforcement of such restorations is undeniable. Computer-Aided Design and Manufacturing (CAD/CAM) processing systems have expanded material alternatives which has triggered the development of many materials for fixed dental prosthetic restorations in attempting to assemble a restorative alternative that can grant enhanced esthetic properties in association with outstanding mechanical performance, thereby leading to long-lasting rehabilitations. In this chapter, we aim to discuss the best evidence available regarding the microstructural differences, intrinsic properties, and clinical performance of different new materials available today for CAD/CAM systems (resin-based composites, polymer-infiltrated ceramic network, zirconia-reinforced lithium silicate, and high translucent zirconia), as well as to describe the topography of available material before and after surface treatments by scanning electron microscopy.

Statement of problem An intraradicular retainer formed by multiple independent glass fiber filaments was developed aiming to allow better adaptation in flattened root canals; however, the performance of the new posts is unclear. Purpose The purpose of this in vitro study was to compare the bond strength (BS) and adhesive interface quality achieved in flattened root canals restored with conventional glass fiber posts (CFPs) and multifilament glass fiber posts (MFPs). Material and methods The distal roots of mandibular molars with long oval root canals were endodontically treated, and the obturation material was removed and assigned to 2 groups (n=11) according to the type of retainer used: CFP (WhitePostDC#0.5; FGM) or MFP (CometTail#4; Synca). The posts were cemented with self-adhesive resin cement. The specimens were sectioned (2 slices per third). The most cervical slice in each third was used to evaluate the BS, while the adhesive interface in the apical slices was analyzed by scanning electron microscopy. BS data were analyzed by using a multilevel generalized linear model, and adhesive interface SEM data were analyzed by using a multilevel ordinal logistic regression model (α=.05). Results Multilevel regression showed a statistically significant difference for the “type of retainer” factor (P=.001; CFP 2.61 ±1.30>MFP 1.59 ±1.54). No statistically significant differences were found for the “root thirds” factor (P=.346) or for the interaction of both factors (P=.114). The failure pattern was predominantly mixed or adhesive for CFP and adhesive to dentin for MFP. A better adaptation of the restorative material was observed in the cervical third for CFP and in the apical third for MFP (P Conclusions MFP resulted in lower BS values than CFP, with a higher prevalence of adhesive failures to dentin and better adaptation of the adhesive interface in the apical third.

Objective: To evaluate the bond strength of different repair treatments for composite resin to aged Y-TZP ceramics. Material and Methods: Zirconia blocks were cut into smaller specimens, sintered according to manufacturer’s recommendations (final dimensions of 4×4×3 mm), and randomly allocated into nine groups (n=15) according to the surface treatment and presence/absence of aging of the substrate (subjected to low-temperature degradation - LTD), as follows: without LTD (Control: without treatment; TBS: tribochemical silica coating + silane + adhesive); with LTD (Control-LTD: without treatment; TBS-LTD: TBS with hydrothermal degradation; MoS-LTD: Monobond S + adhesive; MoP-LTD: Monobond Plus + adhesive; MZP-LTD: Metal/Zirconia Primer + adhesive; USB-LTD: Single Bond Universal; AP-LTD: Alloy primer + adhesive). LTD was simulated in an autoclave (134 °C, 2 bar, 5 h). The ceramic blocks were embedded in PVC cylinders with a self-curing acrylic resin; each surface treatment protocol was performed; a composite resin cylinder (Æ: 3.25 mm and height: 3 mm) was then build-up using split metallic matrices. All the specimens were aged (thermocycling + storage in water for 90 days) and subjected to the shear bond strength test using a universal testing machine (1 mm/min). The failure mode was classified into four types: adhesive, composite resin cohesive fracture, ceramic cohesive fracture, and mixed. The bond strength values were subjected to Mann–Whitney test. Results: Only air-abraded samples (TBS and TBS–LTD) survived thermocycling. More than 80% of the samples of the other groups presented pre-test failures. TBS groups presented higher values of bond strength (3.94) compared to TBS-LTD (0.96). The predominant type of failure for the surviving samples were adhesive. Conclusion: Air particle abrasion is mandatory to improve the bond strength of the Y-TZP substrate; an aged substrate presents an even more unfavorable scenario for adhesion.Keywords Dental prosthesis repair; Hydrothermal degradation; Zirconia; Shear bond strength; Sandblasting.

Statement of problem Data comparing the fatigue performance of adhesively luted glass or polycrystalline ceramic systems for computer-aided design and computer-aided manufacturing (CAD-CAM) are scarce. Purpose The purpose of this in vitro study was to evaluate and compare the fatigue performance of monolithic crowns manufactured from glass or polycrystalline CAD-CAM ceramic systems adhesively luted to a dentin analog. Materials and Methods Fifty-four pairs of standardized preparations of dentin analog (NEMA Grade G10) and simplified ceramic crowns of 1.5-mm thickness were obtained with 3 ceramic materials: lithium disilicate (LD) glass-ceramic (IPS e.max CAD); zirconia-reinforced lithium silicate (ZLS) glass-ceramic (Vita Suprinity); and translucent yttrium fully stabilized polycrystalline zirconia (Trans YZ) (Prettau Anterior). The simplified crowns (n=15) were adhesively cemented onto the preparations and subjected to step-stress fatigue test (initial load of 400 N, 20 Hz, 10 000 cycles, followed by 100-N increment steps until failure). Collected data (fatigue failure load [FFL] and cycles for failure [CFF]) were submitted to survival analysis with the Kaplan-Meier and Mantel-Cox post hoc tests (α=.05) and to Weibull analysis (Weibull modulus and its respective 95% confidence interval). Failed crowns were submitted to fractography analysis. The surface characteristics of the internal surface (roughness, fractal dimension) of additional crowns were accessed, and the occlusal cement thickness obtained in each luted system was measured. Results Trans YZ crowns presented the highest values of FFL, CFF, and survival rates, followed by ZLS and LD (mean FFL: 1740 N>1187 N>987 N; mean CFF: 149 000>92 613>73 667). Weibull modulus and cement thickness were similar for all tested materials. LD presented the roughest internal surface, followed by ZLS (mean Ra: 226 nm>169 nm>93 nm). The LD and ZLS internal surfaces also showed higher fractal dimension, pointing to a more complex surface topography (mean fractal dimension: 2.242=2.238>2.147). Conclusions CAD-CAM monolithic crowns of Trans YZ show the best fatigue performance. In addition, ZLS crowns also showed better performance than LD crowns.

To evaluate the effect of different glass-ceramic surface treatments and aging on the fatigue failure load of a lithium disilicate glass-ceramic adhesively cemented to a dentin analogue material.One hundred and twenty (120) disc-shaped lithium disilicate specimens (Ø=10mm, thickness=1.5mm) were produced and randomly allocated (n=20) into 6 groups, considering 2 study factors: "surface treatment" in 3 levels (SIL-silane application only; HF5+SIL-5% hydrofluoric acid etching and silane application; MEP-etching with an one-step ceramic primer), and "storage" in 2 levels (baseline-storage for 7 days; aging-storage for 90 days+12,000 thermal cycles). Ceramic discs were adhesively cemented to discs of a dentin analogue material (Ø=10mm, thickness=2.0mm) following the manufacturers' instructions. The fatigue failure load was determined by the staircase approach (250,000 cycles; 20Hz; initial load=1050N [∼70% of mean load-to-failure]; step size=52.5N [5% of initial load]). Micro-morphologic, fractographic, and atomic force microscope analysis were also performed. Fatigue failure load data were evaluated by one-way ANOVA, Bonferroni and t-tests for independent samples.HF5+SIL presented higher fatigue failure load in both conditions (baseline and aging); MEP presented intermediary mean values, while the SIL group presented the worst performance. All groups had a statistically significant decrease in the fatigue performance after aging.Hydrofluoric acid followed by silane application showed the best fatigue performance for an adhesively-cemented lithium disilicate ceramic. Aging negatively influenced the fatigue performance for all tested groups.

Made available in DSpace on 2018-12-11T17:15:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2018-01-01 This study aimed to evaluate the effect of etching time and hydrofluoric acid (HF) concentration on the fatigue failure load and surface characteristics of zirconia-reinforced lithium silicate glass (ZLS) ceramic cemented to a dentin-like, fiber reinforced epoxy resin. Ceramic (Suprinity, VITA) (1.0 mm thick) and epoxy resin (2.5 mm thick) discs (10 mm diameter) were produced. The bonding surface of the ceramic samples was nonetched (control group), or etched for 30, 60 or 90 s by 5% or 10% HF. The epoxy resin discs were etched by 10% HF for 30 s followed by the application of an adhesive material (Single Bond Universal, 3M ESPE). Pairs of ceramic/epoxy resin discs were cemented with a dual cure resin cement. The fatigue failure load was determined by the staircase method (500,000 cycles at 20 Hz; initial load = 925 N; step size = 45 N). In 10% HF the etching time was shown to influence the fatigue failure load, which increased as the etching time increased (30 s < 60 s < 90 s), and in 5% HF the fatigue failure load was not shown to be affected by the etching time; the lowest fatigue failure loads were produced in the control group without ceramic etching followed by 10% HF acid etching for 30 s. Topography analysis showed variations based on the etching protocols. All fractures (radial cracks) were shown to originate from defects at the ceramic surface on the cementing interface. For fatigue loading improvements of ZLS ceramic, 10% HF acid etching for 90 s and silanization of the ceramic surface is recommended. PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Units) Univ. Estadual Paulista (UNESP) Institute of Science and Technology at Sao Jose dos Campos PhD Post-Graduate Program in Oral Science (Prosthodontic Units) Faculty of Odontology Federal University of Santa Maria, R. Floriano Peixoto, 1184 MSciD Graduate Program School of Dentistry Meridional Faculty - IMED PhD Post-Graduate Program in Restorative Dentistry (Prosthodontics Units) Univ. Estadual Paulista (UNESP) Institute of Science and Technology at Sao Jose dos Campos

This study evaluated the influence of surface treatments of resin composite substrate on the fatigue behavior of adhesively cemented lithium disilicate glass-ceramic simplified restorations. CAD/CAM lithium disilicate ceramic blocks were shaped into discs (N = 60, O = 10 mm; thickness = 1.0 mm). Resin composite discs (N = 60, O = 10 mm, thickness = 2 mm) were allocated into four groups considering the “surface treatment” factor: Ctrl – no surface treatment; Bur – grinding with coarse diamond bur (#3101G, KG Sorensen); PA – etching with 37% phosphoric acid (15 s); AA – air abrasion with alumina particles (45 μm, 10 mm distance, 2.8 bars, 10 s). The surface topography, the roughness, the fractal dimension (estimated by the box-counting method) and the contact angle analyses were performed after the surface treatments. The lithium disilicate discs were etched (5% hydrofluoric acid, 20 s), silanized and adhesively cemented (Multilink N, Ivoclar Vivadent) on the resin composite discs. The samples (bonded restoration set) were subjected to a step-stress fatigue test at 20 Hz, 10,000 cycles/step with a step-size of 100 N applied on the ceramic surface, having ceramic up and resin composite down. Fractographic analysis was performed. The fatigue data (Fatigue Failure Load – FFL; and Cycles for Failure – CFF) were analyzed by Kaplan Meier with Mantel-Cox log-rank post-hoc tests (α = 0.05). No statistical difference for fatigue performance could be found among the groups (FFL means: 820–867 N; CFF means: 53,195–61,090 cycles). The bur group showed higher surface roughness and contact angle values. The PA group has the highest average fractal dimension. Therefore, the resin composite surface treatment induces topographical changes, however, it has no effect on the fatigue behavior of lithium disilicate restorations.

Made available in DSpace on 2022-04-29T08:32:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 The fatigue behavior and FEA analysis of different ceramic materials cemented over distinct substrates for implant-supported crowns were evaluated in this study. Discs of 10 mm in diameter of both restorative and substrate materials were made and randomly allocated into pairs (n = 15) considering the two study factors: ‘restorative ceramic material’ (1 mm thickness) – polymer-infiltrated ceramic network (PICN), lithium disilicate (LD), zirconia-reinforced lithium silicate (ZLS), or translucent zirconia (TZ); and ‘foundation substrate’ (2 mm thickness) – polyetheretherketone (Peek) or yttrium-stabilized zirconia (YZ). Adhesive cementation was made with a dual cure resin cement. Fatigue testing was run using the step-stress methodology: initial load of 200 N for 5000 cycles, followed by steps of 10,000 cycles starting at 400 N up to 2800 N or until failure, step size of 200 N, frequency of 20 Hz. Data were analyzed by the Kaplan Meier and log-rank post-hoc tests. Fractography analysis (stereomicroscope and SEM) and FEA were also performed. Both factors under study and their interaction statistically influenced the fatigue failure load (FFL), cycles for failure (CFF) and survival rates (p < 0.001). The restorative materials bonded to YZ had higher FFL and CFF than when adhering to Peek, while restorative materials with more crystalline content (TZ and ZLS) showed higher FFL and CFF than LD and PICN. The fractography analysis showed that all materials bonded to YZ resulted in failures starting at the occlusal surface (Hertzian cone cracks), while materials bonded to Peek had radial cracks from the ceramic-cement intaglio surface. FEA analysis showed that tensile stress concentration decreased in the intaglio surface when testing the restorative material over a stiffer (YZ) foundation substrate. In addition, the higher the restorative material's crystalline content, the more the stress is concentrated within the material (TZ > ZLS ≥ LD > PICN) when bonded to the same foundation substrate. Thus, it concluded that a stiffer foundation substrate (YZ) enhances the load-bearing capacity under fatigue of the restorative set; that restorative materials with higher crystalline content results in higher fatigue performance of the set, regardless of the foundation used; and that the foundation material influences the failure pattern of the restorative set. Post-Graduate Program in Oral Sciences (Prosthodontics Units) Faculty of Odontology Federal University of Santa Maria (UFSM) Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos

This study aimed to evaluate and compare the effect of different surface post-processing treatments (polishing, heat treatment, glazing, polishing + heat treatment and polishing + glazing) on the superficial characteristics (micromorphology and roughness), phase transformation and fatigue strength of a Y-TZP ceramic ground with diamond bur. Discs of Y-TZP ceramic were manufactured (ISO:6872-2015; final dimensions of 15mm in diameter and 1.2 ± 0.2mm in thickness) and randomly allocated according to the surface condition: Ctrl - as-sintered; Gr - ground with coarse diamond bur; Gr+HT - ground and subjected to the heat treatment; Gr+Pol - ground and polished; Gr+Pol+HT - ground, polished and heat treated; Gr+Gl - ground and glazed; Gr+Pol+Gl - ground, polished and glazed. The following analyses were performed: roughness (n = 25), surface topography (n = 2), phase transformation (n = 2) and fatigue strength by staircase method (n = 20). All treatments influenced to some extent the surface characteristics of Y-TZP, being that polishing reduced the surface roughness, the m-phase content and improved the fatigue strength; glazing led to the lowest roughness values (Ra and Rz), although it showed the worst fatigue strength; heat treatment showed limited effect on surface roughness, led to complete reversion of the existing m-phase content to t-phase, without enhancing fatigue performance. Thus, a polishing protocol after clinic adjustment (grinding) of monolithic restorations based on polycrystalline zirconia material is mandatory for surface characteristics and fatigue performance improvements.

This study evaluated the effect of contamination with saliva or blood and different cleansing agents on the microtensile bond strength (μTBS) and in situ degree of conversion (DC in situ) of composite-adhesive interface. Sixty-six bovine incisors were ground flat to expose dentin and were randomly assigned to eleven groups (n = 6), according to the contaminant and the cleansing agent. A positive control (without contamination or cleansing agent) was determined. A multimode adhesive in the self-etching form was applied before contamination with blood or saliva. Then, the groups received different cleansing protocols that generated two negative controls (contaminated with saliva or blood and only air dried) and eight experimental groups, washed with water (H2O), ascorbic acid (AscAc10%), hydrogen peroxide 3% (H2O23%) and chlorhexidine 2% (CLX2%). Specimens were restored with composite resin and prepared for μTBS. After 24 h, restored teeth were sectioned and the sticks subjected to the μTBS test (in a universal testing machine at 0.5 mm/min speed). Degree of conversion within the hybrid layer (DC in situ) was evaluated by micro-Raman spectroscopy. Data were analysed using a two-way analysis of variance (ANOVA) and Tukey's test (p 0.05), blood influenced negatively (p = 0.025). However, CLX2% was able to re-establish the values of μTBS and DC in situ (p = 1.0). Weibull regression analysis of μTBS data confirmed the prior mentioned performance. Saliva and cleansing agents did not influence μTBS and DC in situ values, while blood caused them to be significantly decreased. CLX2% was able to reverse the negative effects of blood contamination. In this way, in case of composite-adhesive interface contamination with blood, CLX2% washing was able to reverse the μTBS and DC in situ values.

Made available in DSpace on 2021-06-25T11:02:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-09-01 The aim of this study was to evaluate the effect of in-lab simulation procedures performed on a lithium disilicate ceramic luted to a dentin-analogue material regarding the fatigue performance and topographic changes. Lithium disilicate ceramic (IPS e.max CAD) discs (Ø = 13.5 mm and 1.5 mm of thickness) were produced in different ways: milled in a CAD/CAM system (CAD/CAM – control group); mirror-polished (POL group); produced in-lab and ground with #60 silicon carbide paper (SiC group); with #60 wood sandpaper (WS group); with a fine diamond bur (DB group); or with a CAD/CAM bur adapted in a handpiece with a custom mandrel (MANDREL group). The ceramic discs were adhesively luted (Multilink N) onto dentin analogue discs (Ø = 12 mm and 2 mm of thickness) and fatigue testing (n = 19 discs) was performed by step-stress methodology (initial load of 200 N; step-size of 50 N; 10,000 cycles per step; 20 Hz). Surface roughness and contact angle analysis were also performed. According to Kaplan-Meier and post-hoc Mantel-Cox (log-rank), distinct fabrication methods affected the fatigue performance of bonded glass-ceramic discs (p< 0.001). The CAD/CAM group presented the lowest fatigue failure loads (1250 N) and number of cycles for failure (185,000), while the POL groups obtained the highest results (1752 N; 284,444 cycles). The in-lab groups had intermediate values (1355 – 1526 N; 206,052 – 238,684 cycles). Polished specimens presented the lowest roughness values (Ra = 0.041 μm), while the SiC (1.604 μm), WS (1.701 μm), and MANDREL (1.867 μm) groups showed statistically similar roughness values to the CAD/CAM group (1.738 μm). Despite differences before etching, the contact angle was similar among the milled and simulated groups after etching, except for the polished group. Even with some topographic similarities, the tested in-lab simulation methods were not able to mimic the milled specimens in terms of fatigue findings, leading to distinct magnitude of overestimations of the results. MSciD and PhD Graduate Programs in Oral Science – Prosthodontic Units Faculty of Odontology Federal University of Santa Maria Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos Department of Dental Materials and Prosthodontics Institute of Science and Technology ICT/SJC São Paulo State University – UNESP, São José dos Campos

The present study analyzed the fatigue performance of prefabricated fiber reinforced composite posts (FRC post) with different diameters by means of two different fatigue testing methods. A total of 69 FRC double-tapered posts, presenting 20 mm in length associated with different coronal diameters (1.4, 1.6, 2.0 mm) were embedded with acrylic resin in PVC cylinders, maintaining 6 mm free from the coronal part of the post. The posts of each diameter were submitted to step stress testing (inclination: 45°; initial load: 20 N; step-size: 10 N; cycles per step: 18,000; frequency: 5 Hz) (n = 5) or staircase testing (inclination: 45°; initial load: 60% of the monotonic load-to-fracture reported on existing literature; increment: 10% of the monotonic load-to-fracture reported on existing literature; cycles: 18,000; frequency: 5 Hz) (n = 18). The statistical differences were determined for Kaplan-Meier and Mantel-Cox (Log-Rank) tests for step stress testing and based on confidence interval overlapping for staircase testing. All the failures were analyzed in a stereomicroscope (10 × magnification) after the tests, and representative samples were analyzed by scanning electron microscope (500 × and 1000 × magnification). The FRC post with the wider diameter had greater fatigue failure load in step stress testing (DT1.4–56 N