Influence of ceramic crown design (translucent monolithic zirconia vs. bilayered) of implant-supported single crowns after mechanical cycling.

OBJECTIVES: This study aimed to assess the influence of translucent monolithic versus bilayered crowns and whether the use of a CoCr base abutments affects the fatigue and fracture resistance of screwed implant-supported single crowns with external connections under mechanical cycling. MATERIALS AND METHODS: Fifty specimens were divided into groups: (1) metal-ceramic (MC) crown, (2) veneered zirconia crown (Zr), (3) veneered zirconia crown with a CoCr base abutment (ZrB), (4) monolithic translucent zirconia crown (MZr), and (5) monolithic translucent zirconia crown with a CoCr base abutment (MZrB). Specimens underwent mechanical cycling (5 × 106 cycles; 150 N) evaluating fatigue resistance (number of failures) and those that failed were subsequently subjected to fractographic analyses (stereomicroscope and scanning electron microscope) to evaluate failure location and area, and maximum fracture load was also measured. RESULTS: The failure-related survival rate (100%) and maximum fracture resistance of the MZrB were significantly higher than those of MC and Zr (50%; p < 0.05). There were no significant differences in the failure rate and fracture resistance when a CoCr base abutment was used or not in the translucent monolithic Zr groups (p > 0.05;MZrB vs. MZr). Failure location, with MC crowns' fractures, noted at the screw area (p = 0.043), while all-ceramic crowns were mostly in the cuspid and to failure area, the Zr group had the largest mean (15.55 ± 9.17 mm2) among the groups, significant difference only when compared with MC (1.62 ± 0.81 mm2) (p = 0.025). CONCLUSIONS: Translucent monolithic zirconia crowns exhibited significantly higher fatigue and fracture resistance compared with conventional MC and bilayered crowns. CLINICAL SIGNIFICANCE: The appropriate choice of material and manufacturing technique is crucial for predicting the higher clinical performance of single crowns. Enhanced mechanical resistance in terms of fatigue and fracture resistance can be achieved by replacing MC and bilayered restorations with computer-aided design and computer-aided manufacturing monolithic zirconia.

Comparison of self-etching and conventional bifunctional coupling agent in lithium disilicate ceramic: A systematic review and meta-analysis.

Background: The aim of this systematic review is to determine the effectiveness of self-etching primers in comparison to the conventional protocol with hydrofluoric acid and silane treatment for bonding lithium disilicate ceramics. Material and Methods: The formulated PICO question for this research was: "Does self-etching silane primer surface treatment in lithium disilicate ceramics present a similar bond strength value compared to conventional hydrofluoric acid and silane treatment?". Combinations of words and appropriate truncations were adapted for each database. For the selection, duplicate articles were systematically eliminated using Mendeley software. The Cohen's Kappa statistic was then computed, RoBDEMAT questions were addressed, and the meta-analyses were conducted using RevMan 5.4, at a significance level of 5%. Results: Two independent reviewers conducted a blind and independent analysis of 190219 articles from PubMed, Scopus, Web of Science, and OpenGrey. Subsequently, they extracted data from 21 studies for the systematic review and in 16 the meta-analysis. In all in vitro studies, the most frequently cited concentration of hydrofluoric acid was 5%. In the meta-analysis, no statistical differences were observed between the two treatments concerning bond strength. Conclusions: Self-etching silane primers demonstrate promising results in lithium disilicate bonding, suggesting their potential as an alternative surface treatment to hydrofluoric acids + silane. Key words:Lithium disilicate, Hydrofluoric acid, Dental Porcelain, Ceramics, Silanes.

Color stability and surface roughness of resin-ceramics with different surface treatments: A systematic review and meta-analysis of in vitro studies.

STATEMENT OF PROBLEM: Surface treatments for resin-ceramics have been developed to obtain a smooth surface and improve color stability. However, a consensus on the best treatment for these materials is lacking. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate the color stability and roughness of glass-ceramics versus resin-ceramics with different surface treatments. MATERIAL AND METHODS: The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed, and the study was registered in the open science framework (OSF) for in vitro studies. The population, intervention, control, and outcome (PICO) question was "Is there a difference in color stability and roughness between resin-ceramic vs vitreous ceramics in different surface treatment protocols?" A literature search was performed in PubMed/MEDLINE, Embase, Web of Science, Scopus, Cochrane Library, and ProQuest databases up to January 2023. The Joanna Briggs Institute's critical assessment guidelines for quasi-experimental studies were used for quality assessment. The meta-analysis was based on the inverse variance (IV) method (α=.05). RESULTS: A total of 18 laboratory studies were published between 2015 and 2022, with a total of 2160 specimens, all of which were analyzed qualitatively. The meta-analysis indicated significantly less optical alteration for lithium disilicate ceramics (P<.01; MD: 2.69; 95% CI: 2.00-3.39; I²=89%, P<.01), even when compared with resin-ceramics with polish or sealants (P<.01; MD: 2.45; 95% CI: 1.59-3.30; I²=87%, P<.01) and (P<.01; MD: 3.24; 95% CI: 2.02-4.47; I²=89%, P<.01), while there was no significant difference in surface roughness (P=.08; MD: -0.71; CI 95%: -1.52 to 0.09; I²=87%, P<.01) (P=.33; MD: -0.31; CI 95%: -0.94 to 0.32; I²=87%, P<.01), respectively. CONCLUSIONS: Resin-ceramics that have been polished or treated with sealants have lower color stability than glazed glass-ceramics; however, they are similar in terms of surface roughness.

Polyetheretherketone materials for removable partial denture frameworks: an integrative review.

Polyetheretherketone (PEEK) resin is a high-performance thermoplastic polymer that has been introduced as a possible candidate to replace metallic components in dental prostheses. The objective of this integrative review was to compare, through analysis of studies in the literature, the mechanical performance of removable partial denture frameworks and clasps manufactured with PEEK with the performance of cobalt-chromium (Co-Cr) frameworks and clasps. The guiding question was, "Does the use of PEEK as a substitute for Co-Cr alloys for the construction of removable partial denture frameworks result in better mechanical properties?" The PubMed/ MEDLINE, Embase, Web of Science, Scopus, and SciELO databases were searched for articles published through October 2021. The JBI Critical Appraisal Checklist for Quasi-Experimental Studies was used to assess the methodologic quality of the selected in vitro studies. A total of 208 articles were identified. After the exclusion of duplicates and articles that did not meet the inclusion criteria, 7 studies- -4 in vitro and 3 three-dimensional finite element analyses- -published between 2012 and 2021 were included in the integrative review. The appraisal checklist revealed that the reviewed studies had a low risk of bias and high methodologic quality. The results of the review showed that PEEK alloys have adequate mechanical properties for use in clasps and removable partial denture frameworks, but Co-Cr alloys exhibit better mechanical properties and are more suitable in most circumstances.

Evaluation of the mechanical properties of different materials for manufacturing occlusal splints.

This study aimed to compare the mechanical properties of various occlusal plate materials by analyzing surface roughness, Knoop microhardness, flexural strength, and modulus of elasticity. Fifty samples were prepared and classified as SC (self-curing acrylic resin), WB (heat-cured acrylic resin), ME (acrylic resin polymerized by microwave energy), P (resin print), and M (polymethylmethacrylate polymer block for computer-aided design/computer-aided manufacturing). The data were analyzed using a one-way analysis of variance and Tukey's honestly significant difference test. Surface roughness was the same in all groups. The surface hardness of group M was statistically superior. The samples from groups P and M had higher flexural strength than other samples. The modulus of elasticity of group SC was statistically lower than that of other groups. The mechanical properties of the materials used to make the occlusal plates differed, and group M achieved the best results in all analyses. Therefore, clinicians must consider the material used to manufacture long-lasting and efficient occlusal splints.

Evaluation of bond strength of glass and resin-ceramics with laser phototherapy: A systematic review and meta-analysis of in vitro studies.

STATEMENT OF PROBLEM: Laser phototherapy has been studied as a surface treatment capable of increasing the adhesion of cement to the ceramic surface. However, the bond strength of glass and resin-ceramics after laser phototherapy is unclear. PURPOSE: The objective of this systematic review and meta-analysis was to compare the bond strength of glass and resin-ceramics using laser therapy and conventional hydrofluoric acid etching. MATERIAL AND METHODS: This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was registered in the Open Science Framework (OSF) for in vitro studies. A population, intervention, control, and outcome (PICO) question was formulated: "Does phototherapy promote better bond strength in glass and resin-ceramics than conventional hydrofluoric acid etching?" A literature search was performed in PubMed/MEDLINE, Embase, Web of Science, Scopus, Cochrane Library, and ProQuest databases up to January 2023. The Joanna Briggs Institute critical assessment guidelines for quasi-experimental studies were used for quality assessment. The meta-analysis was based on the inverse variance (IV) method (α=.05). RESULTS: A total of 6 in vitro studies published between 2007 and 2019 with a total number of 348 specimens were included for qualitative analysis; 1 study had a positive effect. Five of the studies were included in the meta-analysis, which indicated a significant decrease for feldspathic ceramics that received laser phototherapy and lithium disilicate (P=.002; MD: -2.15; 95% CI: -3.53 to -0.77; I2=89%, P<.01) and (P<.01; MD: -2.13; 95% CI: -2.99 to -1.27; I2=82%, P<.01), respectively. CONCLUSIONS: Laser irradiation as surface etching of glass ceramics does not produce a bond strength equal to that of conventional hydrofluoric acid etching.

Evaluation of the mechanical properties of different materials for manufacturing occlusal splints

Abstract This study aimed to compare the mechanical properties of various occlusal plate materials by analyzing surface roughness, Knoop microhardness, flexural strength, and modulus of elasticity. Fifty samples were prepared and classified as SC (self-curing acrylic resin), WB (heat-cured acrylic resin), ME (acrylic resin polymerized by microwave energy), P (resin print), and M (polymethylmethacrylate polymer block for computer-aided design/computer-aided manufacturing). The data were analyzed using a one-way analysis of variance and Tukey's honestly significant difference test. Surface roughness was the same in all groups. The surface hardness of group M was statistically superior. The samples from groups P and M had higher flexural strength than other samples. The modulus of elasticity of group SC was statistically lower than that of other groups. The mechanical properties of the materials used to make the occlusal plates differed, and group M achieved the best results in all analyses. Therefore, clinicians must consider the material used to manufacture long-lasting and efficient occlusal splints.

Stress distribution of multiple implant-supported prostheses: Photoelastic and strain gauge analyses of external hexagon and morse taper connections.

Background: To evaluate the stress distribution of three-element prostheses on two different implant systems (External Hexagon (EH) or Morse Taper (MT)) and with two different retention mechanisms (screw-retained or cemented), by photoelastic analysis and strain gauge analyses. Material and Methods: Four photoelastic and 24 strain gauge models of a partially edentulous maxilla were made and were divided in four groups according to connection and retention system: Group I (EH-C) - external hexagon+cement-retained prosthesis; Group II (EH-S) external hexagon+screw-retained prosthesis; Group III (MT-C) - morse taper+cement-retained prosthesis; Group IV (MT-S) - morse taper+screw-retained prosthesis. The implants were installed in the axial position, the first in the region of element 15 and the distal implant in the region of element 17. Loads of 100 N were applied on the occlusal surface of the prosthesis for 10 seconds. For the photoelasticity analysis, photographic images were taken and were evaluated according to the number of high-intensity fringes. For the strain gauge analysis, the strain gauges were positioned on the marginal crest of the implants and on the apical region, being numbered for analysis of the stress distribution in each region. The electrical signals were captured and processed by specific software. Results: Higher concentration of tension was observed in the apical region of the implants and mainly in the distal implant, where the formation of fringes was higher. The microstrain values obtained for each group were similar: EH-C (454±18,3 µÉ›); EH-S (469±94 µÉ›); MT-C (466±49,8 µÉ›); MT-S (460±36,6 µÉ›). It was observed that apical position had higher stress concentrations for all analyzed groups. Conclusions: The different connections and fixation mode did not interfere in the amount of tension generated in the tissue adjacent to the implant, also the region that generated the greatest amount of tension was in the apical region of the anterior implant. Key words:Dental implants, biomechanics, fixed prosthodontics.

Silica deposition on zirconia via room-temperature atomic layer deposition (RT-ALD): Effect on bond strength to veneering ceramic.

PURPOSE: To develop and to characterize a hybrid interface between yttria-stabilized zirconia (Y-TZP) transformed layer and silica-based nanofilm to enable a better bonding between Y-TZP and a veneering ceramic. MATERIAL AND METHODS: Sixty-six fully-sintered rectangular Y-TZP specimens were distributed into 6 groups, according to the surface treatment applied: C (control): no treatment; Al: 27 µm-alumina particle abrasion; Ht: hydrothermal treatment in autoclave for 15h; Si20: 20 cycles of silica deposition using room-temperature atomic layer deposition (RT-ALD); Si40: 40 cycles of RT-ALD; Ht + Si40: hydrothermal treatment followed by 40 cycles of RT-ALD. RT-ALD was performed by the sequential exposure of specimens to vapor of tetramethoxysilane orthosilicate (TMOS) and ammonium hydroxide (NH4OH). Y-TZP surface wettability and shear bond strength (SBS) between Y-TZP and the veneering ceramic were analyzed for all groups after surface treatments. One-way ANOVA and Tukey's HSD test were used for data analysis (p ≤ 0.05). RESULTS: The highest contact angle was observed for the control group (64.46 ± 6.09 θ), while the lowest values (p < 0.001) were presented after Si20 (29.85 ± 4.23 θ) and Si40 (30.37 ± 5.51 θ) treatments. Hydrothermal treatment (49.3 ± 2.69 θ) and alumina abrasion (45.84 ± 4.12 θ) resulted in intermediate contact angle values. The highest SBS values were observed for Al (16.74 ± 1.68 MPa) and Ht (15.27 ± 2.11 MPa) groups (p < 0.018). Groups Si20 (9.66 ± 1.22 MPa), Si40 (9.33 ± 2.11 MPa), Ht + Si40 (9.37 ± 1.02 MPa) and C (12.54 ± 2.64 MPa) all resulted in similar SBS results (p > 0.998). CONCLUSION: The experimental treatments proposed enhanced surface wettability, but shear bond strength between Y-TZP and veneering ceramic was not improved. Alumina particle-abrasion improved SBS values while a decrease in wettability was observed.

Dentistry and Intensive Care Unit: A Brief Report.

OBJECTIVE: The aim of this study is to verify whether removable dentures of patients admitted to an intensive care unit (ICU) are niches of microorganisms that can cause pathologies (Staphylococcus aureus, Candida spp., and enterobacteria). MATERIALS AND METHODS: Fifteen patients who were denture wearers (removable partial denture and complete denture) were included in this study. Patients must wear their dentures daily, and these dentures must have acrylic parts. Microbial biofilm was collected from the acrylic part of one denture of each patient. Then, the biofilm was seeded on different culture media: Sabouraud agar, blood agar, MacConkey agar, and mannitol salt agar. In this study, biochemical evaluations of microorganisms were performed. STATISTICAL ANALYSIS: The percentage of dentures with the microorganism identified by each culture medium was calculated. RESULTS: In total, 100% of the dentures were positive for Staphylococcus spp. (blood agar) and Candida spp. (Sabouraud agar); 33.3% of the dentures were positive for S. aureus (Mannitol salt agar); and 13.3% of the dentures were positive for Shigella spp. (MacConkey agar). CONCLUSION: Removable dentures of patients (removable partial dentures and complete dentures) admitted to an ICU are niches of microorganisms that can cause pathologies.

Survival and complications of monolithic ceramic for tooth-supported fixed dental prostheses: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Although recent studies have reported the success of implant-supported monolithic restorations, consensus on the use of monolithic ceramic restorations is lacking. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate the survival and biological and technical complication rates of monolithic single crowns and fixed partial dentures (FPDs). MATERIAL AND METHODS: An electronic search was conducted by 2 independent authors on the PubMed/MEDLINE, Scopus, and Cochrane Library databases. The Newcastle-Ottawa scale and Cochrane risk of bias tool were used to assess the quality and risk of bias of the included studies. Meta-analysis was performed by using the R software program. RESULTS: The search identified 763 articles, 18 of which met the eligibility criteria. A total of 15 studies evaluated monolithic ceramic single crowns, and 4 studies evaluated FPDs. The studies included 1061 monolithic single crowns (524 lithium disilicate, 461 zirconia, and 76 polymer-infiltrated ceramic network [PICN]) and 104 FPDs (36 lithium disilicate and 68 zirconia). Meta-analysis of single-arm studies indicated the proportion of survival, biological, and technical complication rates of 1% (95% confidence interval [CI]: 0% to 3%), 1% (CI: 0% to 4%), and 2% (CI: 1% to 4%), respectively, for single crowns, independent of ceramic material, and 3% (CI: 0% to 34%), 5% (CI: 1% to 21%), and 5% (CI: 1% to 21%) for FPDs, respectively. Only 5 studies performed a direct comparison between monolithic and veneered ceramic restorations, and no significant difference was observed in terms of survival (risk ratio [RR]: 0.68; CI: 0.25-1.91; P=.96), biological (RR: 0.69; CI: 0.31-1.53; P=.35), and technical complication rates (RR: 0.87; CI: 0.40-1.88; P=.29). CONCLUSIONS: The use of monolithic ceramic can be considered a favorable treatment for tooth-supported single crowns and FPDs, with high survival and low complication rates. However, further randomized controlled trials are needed to reassess these clinical performances, mainly by comparing them with the performance of veneered restorations.

Surface characterization of different surface treatments associations with plasma and bonding analysis of Y-TZP and the veneering ceramic.

OBJECTIVES: To characterize the surface of zirconia (Y-TZP) submitted to different surface treatments (with and without plasma associations) and to evaluate the shear bond strength (SBS) between veneering ceramic (VC) and Y-TZP after different aging methods. METHODS: 301 Y-TZP specimens were fabricated and distributed into 7 groups: C (control): no treatment; Al: airborne abrasion with 27 µm Al2O3 particle; L: liner; P: plasma; Al + L: airborne + liner; Al + P: airborne + plasma; P + L: plasma + liner. The Y-TZP surface was characterized by SEM, EDS, AFM, surface profilometry, surface-free energy (SFE), and XRD. SBS between Y-TZP and VC was verified after three aging protocols: initial, after hydrothermal aging (autoclave for 5 h), or thermal fatigue (30,000 baths - 5-55 °C). One- (profilometry, SFE) and two-way ANOVA (SBS), and Tukey's HSD test were used. RESULTS: For the plasma groups, a full globular surface coverage was observed (SEM, AFM). Si was found for Al, L, Al + L, and P + L. Roughness was lower for C, P, and Al + P. For SFE, the highest values were found when the liner was applied (>74.59 nm/Nm). The highest monoclinic content was observed for Al + L (6.96%) and Al + P (5.86%). For the initial period, Al and P + L presented the lowest SBS values (<5.85 MPa; P > 0.331). The highest SBS values were found for L, P, and P + L (hydrothermal aging) and for P, L, Al + L, and Al + P (thermal fatigue). SIGNIFICANCE: Changes in Y-TZP topography and the SBS with the VC were found, according to treatments performed. Plasma treatment improved SBS and did not cause phase transformation.

Effect of laser irradiation on bond strength between zirconia and resin cement or veneer ceramic: A systematic review and meta-analysis.

Aim: This systematic review with meta-analysis aimed to evaluate the effect of the laser treatment on bond strength between Y-TZP and the resin cement or with the veneering ceramic, and the effect on the alteration of the Y-TZP surface roughness. Settings and Design: Systematic review and meta analysis following PROSPERO guidelines. Materials and Methods: A comprehensive review was performed up to September 2020 on four databases (PubMed/MEDLINE, Embase, Scopus, and Cochrane Library), using the combination of keywords: "laser AND zirconia AND surface treatment AND bond strength". Statistical Analysis Used: The meta-analysis was based on the Mantel-Haenszel and inverse variance methods. The continuous outcome was evaluated by mean difference and the corresponding 95% confidence intervals. Results: A total of 37 studies were identified for the inclusion of data, with only in vitro studies. The types of laser reported in the studies were: Er:YAG, Nd:YAG, Er,Cr:YSGG, CO2, Femtosecond, and Yb lasers. A random-effect model found statistically significant differences between lasers and control groups of Y-TZP (P < 0.00001; MD: 3.08; 95% CI: 2.58 to 3.58). Only the bond strength with the Er:YAG laser did not present statistical difference (P = 0.51; MD: 0.22; 95% CI: -0.44-0.88). In another analysis, a random-effect model found a statistically significant difference between the laser and control groups on surface roughness (P < 0.00001; MD: 0.96; 95% CI: 0.86 to 1.06). Conclusions: Laser irradiation is capable to improve the Y-TZP surface roughness and the bond strength of zirconia with resin cement and veneering ceramics. However, there is a lack of laser protocol for the zirconia surface, a fact that makes a simple and direct comparison difficult.

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

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

Influence of Different Pigmentations and Accelerated Aging on the Hardness and Tear Strength of the A-2186 and MDX4-4210 Silicones.

OBJECTIVE: To evaluate the influence of different pigmentations and accelerated aging on the hardness and tear strength of the A-2186 and MDX4-4210 silicones. MATERIALS AND METHODS: The samples A-2186 and MDX4-4210 were manufactured without and with pigmentations (black, bronze, and pink). For the Shore A hardness test, 80 samples of each silicone were fabricated, and for the tear strength test, 320 samples of each silicone were fabricated. Eight groups were created for each test (n = 10). These tests were performed before and after 252, 504, and 1008 hours of aging. Three-way repeated-measures analysis of variance and the Tukey test were performed (α = 0.05). RESULTS: The A-2186 silicone showed higher hardness and tear strength when compared with the MDX4-4210 silicone (p < 0.05), except in the hardness of the A-2186 and MDX4-4210 groups without pigmentation after 1008 hours (p > 0.05). All hardness values were between 25 and 35 units, regardless of the silicone type, period, and pigmentation (or no pigmentation). In most situations, the hardness of silicones used increased after 252 hours (p < 0.05). The nonpigmented MDX4-4210 group and all A-2186 groups showed an increase in tear strength after 252 hours (p < 0.05). For the nonpigmented MDX4-4210 group, from 252 to 1008 hours, there was no change in tear strength (p > 0.05). All pigmented MDX4-4210 groups showed no change in tear strength from 0 (initial) to 1008 hours of aging (p > 0.05). In all A-2186 groups, from 252 to 504 hours, there was a reduction in tear strength (p < 0.05), and from 504 to 1008 hours, there was an increase in tear strength (p < 0.05), except in the bronze A-2186 group (p > 0.05). CONCLUSION: In most situations, the A-2186 silicone showed significantly higher values of hardness and tear strength than the MDX4-4210 silicone. All hardness values were considered clinically acceptable. Accelerated aging could increase, decrease, or not significantly change the hardness and tear strength of the silicones used. The results of hardness and tear strength suggest that MDX4-4210 was more influenced by the presence of pigmentation after aging.

Bond strength of lithium disilicate after cleaning methods of the remaining hydrofluoric acid.

BACKGROUND: Different ceramic surface cleaning methods have been suggested after the acid conditioning. The aim was to evaluate the effect of different protocols used to remove the remaining hydrofluoric acid on the shear bond strength (SBS) between lithium disilicate and resin cement. MATERIAL AND METHODS: Forty-four specimens of lithium disilicate (IPS e.max Press) were divided in 4 groups (n=11): group C (control, no treatment); group HF+S (5% hydrofluoric acid + silane); group HF+US+S (5% hydrofluoric acid + ultrasound cleaning + silane); group HF+PH+S (5% hydrofluoric acid + 37% phosphoric acid + silane). Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were performed to characterize the surface morphology. The SBS test was performed on the resin/ceramic interface, and the failure mode was characterized. SBS values were submitted to 1-way ANOVA and the Tukey test (α=.05). The relation between surface treatment and failure modes was analyzed using the chi-squared test (α=.05). RESULTS: The surface treatment type interfered in the shear strength (p<.001) and higher SBS values were observed for the groups HF+US+S (17.87 MPa) and HF+PH+S (16.37 MPa). The surface treatment did not influence the failure mode (p=.713). No fluorsilicate salts were observed after ultrasound cleaning. CONCLUSIONS: The utilization of ultrasound cleaning was an effective procedure to remove remaining fluorsilicate salts, promoting the highest SBS values. Key words:Bond strength, ceramics, fluorsilicate, lithium disilicate, resin cement.

Cytotoxicity and inflammatory response of different types of provisional restorative materials.

AIM: To evaluate the cytotoxicity and inflammatory response of different types of provisional restorative materials to mice gingival fibroblasts. METHODS: Cytotoxicity of provisional material discs (thermal-polymerized acrylic resin; auto-polymerized acrylic resin; bisacrylic resin; nano-ceramic resin for CAD/CAM and prefabricated polymer block for CAD/CAM) to Mice (Balb/c) gingival cell were investigated under direct and indirect contact (extracts) at 24, 48 and 72 h, using the MTT and Alamar blue assays. Materials extracts (24 h) were applied to the cell culture (indirect contact) or cells were seeded on discs of provisional materials, and the cytotoxicity and production of IL-6, IL-1ß and TNF-α after 24, 48 and 72 h were analyzed through MTT, Alamar Blue® and ELISA. Culture medium was used as control for indirect contact assay (extract) and the surfaces of the wells without discs of provisional materials were used as control for direct contact assay. Results were analysed statistically by ANOVA followed by the Bonferroni-Test correction. Statistically significant differences were considered if P was < .05. RESULTS: Auto-polymerized and bisacrylic resins (direct contact) reduced cell viability after 24, 48 and 72 h compared to control (P < .05). Indirect contact (extract) was not cytotoxic to cells at all periods compared to control (P > .05). Auto-polymerized and bisacrylic resins increased IL-6, IL-1ß and TNF-α levels mainly at 24 h when compared to the other materials (P < .001). CONCLUSION: Auto-polymerized and bisacrylic were more cytotoxic to mice gingival fibroblasts. CAD/CAM nano ceramic resin and prefabricated polymer blocks are more predictable materials to preserve the periodontal soft tissues.

Stress distribution in fixed mandibular prostheses fabricated by CAD/CAM and conventional techniques: Photoelastic and strain gauge analyses.

BACKGROUND: The aim of this study was to evaluate the distribution of stress in complete fixed mandibular prostheses with infrastructures (IE) fabricated with different materials and techniques, under compressive force. MATERIAL AND METHODS: A model of an edentulous mandible, which received five 4x11 mm external hexagon implants between the mental foramens, was fabricated. The groups were divided into: Group I - IE in nickel-chromium with an acrylic resin occlusal coating; Group II - IE in nickel-chromium with a ceramic occlusal coating; Group III - IE milled in zirconia with a ceramic coating. For the photoelastic methodology, 70 N axial loads were applied in three regions. Photographic images were taken and analyzed according to the number of high-intensity fringes. For the strain gauge methodology, the measurement of stresses was performed in two distinct regions. The same compression tests described earlier were then performed. The registered stress values were grouped in tables and submitted to two-factor variance analysis (ANOVA) and the Tukey test with 5% significance. RESULTS: The results of the two methodologies demonstrated smaller stress values for Group I, when compared to the other groups. CONCLUSIONS: It was possible to conclude that the complete fixed prostheses, with infrastructures cast in metal and acrylic occlusal coating, demonstrated better biomechanical results. Key words:Dental implants, mandibular prosthesis implantation, biomechanics.

O desafio do restabelecimento de um sorriso antiestético por meio de prótese fixa metal-free / The challenge of restoring an unsightly smile by means of a fixed metal-free prosthesis / El desafío del restablecimiento de una sonrisa antiestética por medio de prótesis fija metal-free

Para alcançar a estética em dentes anteriores deve-se ter conhecimento de diversas técnicas e principalmente fazer a escolha correta dos materiais. As cerâmicas odontológicas estão cada vez mais presentes nas restaurações, visto que possuem ótimas propriedades ópticas e mecânicas. Assim, o objetivo deste estudo foi proporcionar a estética em dentes anteriores com diferentes subtratos através de uma prótese fixa metal-free. Paciente do gênero masculino, 38 anos, procurou atendimento queixando-se da estética do seu sorriso. No exame clínico foi observada uma coroa total metalocerâmica no elemento 21 e facetas de resina composta nos elementos 11,12 e 22, todas com estética insatisfatória. O dente 21 apresentava um núcleo metálico fundido adequado e os dentes 12 e 22 com tratamentos endodônticos. Foi proposta a instalação de pinos de fibra de vidro nos dentes 12 e 22. Além, da confecção de coroas totais metais-free em dissilicato de lítio nos quatro incisivos superiores com o sistema e-max ceram. O resultado final estético e funcional foi aprovado pelo paciente e pelos profissionais envolvidos(AU)

To achieve aesthetics in anterior teeth one must be aware of several techniques and especially make the correct choice of materials. Dental ceramics are increasingly present in restorations, since they have excellent optical and mechanical properties. Thus, the objective of this study was to achieve esthetics in anterior teeth with different substrate through a fixed prosthesis metal-free. A male patient, 38 years old, sought care complaining about the aesthetics of his smile. In the clinical examination a total metaloceramic crown was observed in element 21 and composite resin facets in elements 11,12 and 22, all with unsatisfactory aesthetics. Tooth 21 had a suitable molten metal core and teeth 12 and 22 with endodontic treatments. It was proposed to install fiberglass pins on the teeth 12 and 22. In addition, from the manufacture of total metal-free crowns in lithium disilicate in the four upper incisors with the e-max system ceram. The final aesthetic and functional result was approved by the patient and the professionals involved(AU)

Para alcanzar la estética en dientes anteriores se debe tener conocimiento de diversas técnicas y principalmente hacer la elección correcta de los materiales. Las cerámicas dentales están cada vez más presentes en las restauraciones, ya que poseen óptimas propiedades ópticas y mecánicas. Así, el objetivo de este estudio fue proporcionar la estética en dientes anteriores con diferentes sustratos a través de una prótesis fija metal-free. Paciente del género masculino, 38 años, buscó atención quejándose de la estética de su sonrisa. En el examen clínico se observó una corona total metalocerámica en el elemento 21 y facetas de resina compuesta en los elementos 11,12 y 22, todas con estética insatisfactoria. El diente 21 presentaba un núcleo metálico fundido adecuado y los dientes 12 y 22 con tratamientos endodónticos. Se propuso la instalación de pines de fibra de vidrio en los dientes 12 y 22. Además, de la confección de coronas totales metales libres en disilicato de litio en los cuatro incisivos superiores con el sistema e-max ceram. El resultado final estético y funcional fue aprobado por el paciente y los profesionales involucrados(AU)

Reabilitação estética anterior associando prótese metalocerâmica e prótese fixa metal-free: relato de caso / Previous aesthetic rehabilitation associated with metaloceramic prosthesis and fixed metal-free prosthesis: case report / Rehabilitación estética anterior asociando prótesis metalocerámica y prótesis fixa metal-free: reporte de caso

Devido a evolução dos sistemas cerâmicos, atualmente, são permitidas inúmeras associações de materiais restauradores. Entretanto, mimetizar as características visuais das próteses livres de metal com próteses metalocerâmica permanece um desafio. Assim, o objetivo deste trabalho foi relatar o caso clínico de substituição de próteses desadaptadas, homogeneizando próteses parciais fixas livres de metal e metalocerâmicas dento e implantossuportadas, após cirurgia periodontal. O paciente de 55 anos, gênero masculino, compareceu à Clínica de Prótese Parcial Fixa, da Faculdade de Odontologia de Araçatuba ­ FOA/UNESP em 2017 queixando-se dos seus dentes anteriores estarem "feios" e com a "raiz aparecendo". No exame clínico foi constatada recessão gengival nos elementos 11 e 13, os quais continham uma prótese parcial fixa de três elementos metalocerâmicas desadaptada, prótese sobre implante nos elementos 21 e 22, que apresentavam-se desadaptadas e com estética desfavorável. No exame radiográfico pôde-se observar a presença de um núcleo metálico fundido nos elementos 11 e 13. Foi proposto, então, a confecção de coroas totais livres de metal nos elementos anteriores superiores (13, 12, 11, 21 e 23) e coroa metalocerâmica para o elemento 22. Para isso, foi realizado enceramento diagnóstico inicial e, após o consentimento do paciente, foi efetuada a remoção das próteses antigas. Com a remoção, visualizamos uma . depressão na vestibular do rebordo na área do 12 (ausente), solucionado com um enxerto gengival subepitelialApós a realização dos preparos dentários e moldagem com silicone de adição as peças foram confeccionadas com sistema e.max Ceram (Ivoclar Vivadent). Após a prova estética e ajustes oclusais iniciais, as peças foram preparadas para cimentação resinosa com o sistema Variolink® N (Ivoclar Vivadent). O cimento transparente Conclui-se que, apesar da disparidade dos materiais, é possível mimetizá-los e foi selecionado previamente por meio de provas com o kit Try-In.oferecer resultados reabilitadores suficientemente estéticos e satisfatórios(AU)

Due to the evolution of ceramic systems, numerous associations of restorative materials are now permitted. However, mimicking the visual characteristics of metal-free prostheses with metal-ceramic dentures remains a challenge. Thus, the objective of this study was to report the clinical case of replacement of maladaptive dentures, homogenizing denture free and fixed metal partial dentures and implants supported after periodontal surgery. The patient, 55 years old, male, attended the Fixed Partial Prosthesis Clinic of the Faculty of Dentistry of Araçatuba - FOA / UNESP in 2017 complaining that his anterior teeth were "ugly" and with the "root appearing". In the clinical examination, gingival recession was observed in elements 11 and 13, which contained a fixed partial prosthesis of three maladaptive metal-ceramic elements, a prosthesis on implants in elements 21 and 22, the prostheses were maladapted and unfavorable esthetics. In the radiographic examination it is possible to observe the presence of a molten metal nucleus in elements 11 and 13. It was proposed, then, the manufacture of free metal crowns in the upper anterior elements (13, 12, 11, 21 and 23) and crown PFM for the element 22. For this, it performed waxing initial diagnosis and after the patient's consent, the removal of the old prosthesis were performed. Upon removal, a depression visualize the buccal flange in the area 12 (absent), solved with a subepithelial gum graft. After the dental preparations and molding with silicone of addition the pieces were made with e.max Ceram system (Ivoclar Vivadent). After the initial test and aesthetic occlusal adjustments, the pieces were prepared for cementing with resin Variolink® N system (Ivoclar Vivadent). The clear cement was previously selected by the test realized with Try-In kit. We conclude that, despite the disparity of materials, it is possible to mimic them and offer rehabilitative results sufficiently aesthetic and satisfactory(AU)

Debido a la evolución de los sistemas cerámicos, actualmente, se permiten numerosas asociaciones de materiales restauradores. Sin embargo, mimetizar las características visuales de las prótesis libres de metal con prótesis metalocerámicas sigue siendo un desafío. Así, el objetivo de este trabajo fue relatar el caso clínico de sustitución de prótesis desadaptadas, homogeneizando prótesis parciales fijas libres de metal y metalocerámicas dento e implantosuportadas, después de cirugía periodontal. El paciente de 55 años, género masculino, asistió a la Clínica de Prótesis Parcial Fija, de la Facultad de Odontología de Araçatuba - FOA / UNESP en 2017 quejándose de sus dientes anteriores estar "feos" y con la "raíz apareciendo". En el examen clínico se constató recesión gingival en los elementos 11 y 13, los cuales contenían una prótesis parcial fija de tres elementos metalocerámicos desadaptados, prótesis sobre implante en los elementos 21 y 22, las prótesis se presentaban desadaptadas y con estética desfavorable. En el examen radiográfico se puede observar la presencia de un núcleo metálico fundido en los elementos 11 y 13. Se propuso entonces la confección de coronas totales de metal en los elementos anteriores superiores (13, 12, 11, 21 y 23) y corona metalocerámica para el elemento 22. Para ello, se realizó el encerado diagnóstico inicial y, tras el consentimiento del paciente, se efectuó la remoción de las prótesis antiguas. Con la remoción, visualizamos una depresión en la vestibular del borde en el área del 12 (ausente), solucionado con un injerto gingival subepitelial. Después de la realización de los preparados dentales y moldeo con silicona de adición las piezas fueron confeccionadas con sistema e.max Ceram (Ivoclar Vivadent). Después de la prueba estética y ajustes oclusales iniciales, las piezas fueron preparadas para cementación resinosa con el sistema Variolink® N (Ivoclar Vivadent). El cemento transparente fue seleccionado previamente por medio de pruebas con el kit Try-In. Se concluye que, a pesar de la disparidad de los materiales, es posible mimetizarlos y ofrecer resultados rehabilitadores suficientemente estéticos y satisfactorios(AU)