Is zirconia surface etching a viable alternative to airborne particle abrasion? A systematic review and meta-analysis of in vitro studies.

OBJECTIVES: This systematic review aimed to determine the effectiveness of various etching surface treatments on zirconia bond strength with the following research question: "Can zirconia etching serve as a viable alternative to airborne particle abrasion (APA) for achieving reliable bonding?". DATA: In vitro studies comparing APA, performed with either conventional or silica-coated aluminum oxide (Al2O3) particles, with various etching protocols in terms of bonding performance were included. The risk of bias of the included studies was assessed using the QUIN's tool for in vitro studies. Meta-analyses were performed using RevMan; random-effects models were applied, and heterogeneity was tested using the I2 index. The significance level was set at p < 0.05. SOURCES: A comprehensive literature search was conducted across electronic databases, including Clarivate Analytics' Web of Science, Cochrane Library, EMBASE, PubMed, Scopus and ProQuest. STUDY SELECTION: Fifty-four relevant articles were included in this systematic review. According to the QUIN's tool, 7 studies were rated as "high risk of bias", 46 studies were rated as "medium risk", and 1 study was rated as "low risk". Nineteen studies were used for meta-analyses. Mostly, APA demonstrated significantly higher bond strength compared to various etching protocols (p < 0.05). However, no statistical difference was found between APA and high concentrations (40-48 %) of hydrofluoric acid (HF) in terms of immediate- and medium-term bond strength to resin composite (p > 0.05). On enamel, an experimental hot etching solution performed significantly better than APA in short-term follow-up (p < 0.05). A novel multi-acid solution exhibited significantly higher immediate shear bond strength to resin cement than APA (p < 0.05). Variable heterogeneity, ranging from low to high, was observed. CONCLUSIONS: APA remains the surface treatment with the strongest evidence in the literature and it is usually more efficacious than zirconia etching. However, highly concentrated HF and an experimental hot etching solution have demonstrated similar or significantly higher bond strength values over time compared to APA, depending on the adhesive substrate. A recently introduced multi-acid solution (Zircos-E) needs to be further explored, especially in regards to long-term bond durability. CLINICAL SIGNIFICANCE: This systematic review provides a comprehensive analysis of the existing in vitro evidence on the potential of zirconia etching and the bond durability of resin-based materials after artificial aging. Selecting appropriate surface treatment protocols is crucial for achieving optimal clinical outcomes.

Does the internal surface treatment technique for enhanced bonding affect the color, transparency, and surface roughness of ultra-transparent zirconia?

PURPOSE: To investigate the effects of different surface treatments and thicknesses on the color, transparency, and surface roughness of ultra-transparent zirconia. METHODS: A total of 120 Katana ultra-translucent multi-layered zirconia specimens were divided into 12 groups according to the thickness (0.3, 0.5, and 0.7 mm) and surface treatment (control, airborne particle abrasion [APA], lithium disilicate coating, and glaze on). Color difference (ΔE00) and relative translucency parameter (RTP00) were calculated using a digital spectrophotometer. The surface roughness (Ra, Rq, Sa, and Sq) was measured using a non-contact profile scanner. The surface morphologies and microstructures of the samples were observed using a tungsten filament scanning electron microscope. Statistical analyses were performed by one-way and two-way analysis of variance (ANOVA) followed by post hoc multiple comparisons and Pearson's correlation (α = 0.05). RESULTS: The results showed that the surface treatment, ceramic thickness, and their interactions had significant effects on ΔE00 and RTP00 (p < 0.001). The surface treatment significantly altered the micromorphology and increased the surface roughness of the ceramic samples. APA exhibited the lowest transparency, largest color difference, and highest surface roughness. Zirconia with 0.3 mm and 0.7 mm thicknesses showed strong negative correlations between Sa and RTP00. CONCLUSIONS: The three internal surface treatments significantly altered the surface roughness, color difference, and transparency of ultra-transparent zirconia. As the thickness increased, the influence of the inner surface treatment on the color difference and transparency of zirconia decreased. CLINICAL IMPLICATIONS: For new zirconia internal surface treatment technologies, in addition to considering the enhancement effect on the bonding properties, the potential effects on the color and translucency of high-transparency zirconia should also be considered. Appropriately increasing the thickness of zirconia restorations helps minimize the effect of surface treatment on the optical properties.

Surface Modification of Feldspathic Ceramic Used for Minimally Invasive Restorations: Effect of Airborne Particle Type on the Surface Properties and Biaxial Flexural Strength.

This study aimed to evaluate the effect of airborne particle abrasion with different particles on the surface free energy, roughness, and biaxial flexural strength of a feldspathic ceramic by comparing it with hydrofluoric acid etching, the standard surface treatment, and polishing. Square-shaped feldspathic ceramic specimens (12 mm × 12 mm × 1.2 mm) were divided into subgroups as airborne particles abraded with alumina (AO3a, AO3b, AO25, AO50a, AO50b, AO90, AO110a, AO110b, AO120a, and AO120b), silica (SO50a, SO50b, SO100, and SO100/200), or nutshell granule (NS100/200), hydrofluoric acid etched, and polished (n = 12). Surface free energy (n = 5), roughness (n = 5), biaxial flexural strength (n = 12), and Weibull moduli (n = 12) were investigated. Data were evaluated with 1-way ANOVA and Tukey HSD tests, and possible correlations were investigated with Pearson's correlation (α = 0.05). SO100/200 mostly had lower surface free energy (p ≤ 0.011), and polishing and etching led to higher surface free energy than AO3a, AO3b, and AO120a (p ≤ 0.031). Polished, SO100, and SO50b specimens mostly had lower roughness and AO125 had the highest roughness (p ≤ 0.029). SO100/200 mostly had lower biaxial flexural strength (p ≤ 0.041), and etched specimens had higher biaxial flexural strength than AO120a, AO120b, and SO50b (p ≤ 0.043). AO3b had the highest (33.56) and AO120b had the lowest (11.8) Weibull modulus. There was a weak positive correlation between the surface free energy and the biaxial flexural strength (r = 0.267, p = 0.011). A larger particle size mostly resulted in higher roughness, which was also affected by the particle shape. Most of the test groups had similar biaxial flexural strength to that of the hydrofluoric acid-etched group. Therefore, for tested feldspathic ceramic, airborne particle abrasion with tested parameters may be a suitable alternative without causing any further damage.

Relative Health Risk Reduction from an Advanced Multi-Modal Air Purification System: Evaluation in a Post-Surgical Healthcare Setting.

Advanced air treatment systems have the potential to reduce airborne infection risk, improve indoor air quality (IAQ) and reduce energy consumption, but few studies reported practical implementation and performance. PlasmaShield®, an advanced multi-modal HVAC-integrated system, was directly compared with a standard MERV-13 system in a post-surgical paediatric healthcare setting. The evaluation entailed monitoring of multi-size airborne particles, bioaerosols and key IAQ parameters. Measurements were taken for outside air, supply air and air in the occupied space for 3 days prior to, and after, the installation of the PlasmaShield system. Compared with the existing arrangement, very significant reductions in particle number concentrations were observed in the occupied space, especially with virus-like submicron particles. Significant reductions in airborne culturable bacteria and fungi were observed in the supply air, with more modest reductions in the occupied space. In the case of virus-like particles, there was an eight-fold improvement in equivalent clean air, suggesting a five-fold infection risk reduction for long-range exposure. The data suggest multiple benefits of airborne particle and bioaerosol reduction, with applications beyond healthcare. Long-term studies are recommended to confirm the combined IAQ, health and energy benefits.

Operating Room Airborne Microbial Load: Nonscrubbed Staff Apparel Matters.

BACKGROUND: Infection is a leading cause of total joint arthroplasty failure. In previous studies, we found correlations between the level of contamination, concentrations of airborne particles, and the number of staff present. In this study, we focused on the apparel of nonscrubbed operating room (OR) staff to elucidate their contribution to the airborne microbial load. METHODS: We compared hospital-laundered scrubs to disposable coveralls using 2 methods. (1) Participants entered an isolation chamber with a controlled environment and completed tasks for 1 hour wearing both the approved and alternative OR attire. Settle plates collected viable contaminants that were shed by the participants during testing. (2) Lab members conducted standardized maneuvers in a functional OR that simulated typical movements of the nurse, anesthesiologist, implant representative, and entering/exiting staff. An airborne particle counter and settle plates were positioned throughout the OR. After 1 hour, the staff changed apparel and repeated the test. Each session of both phases consisted of 2 tests by the same individuals on the same day. RESULTS: There was approximately a 10-fold difference in the settlement rate of viable particles between groups when employing the isolation chamber. The settle rate for scrubs was 5,519 ± 1,381 colony forming units (CFUs)/m2/h, while the settle rate for coveralls was 505 ± 55 CFUs/m2/h (P = .008). During testing in the OR, 218.7 ± 35 CFUs/m2/h were captured for scrubs, compared with 50.5 ± 13 CFUs/m2/h for the coverall (P < .01). The concentration of airborne particles collected for scrubs was 4,952.1 ± 495 particles/m3 and 1,065 ± 53 particles/m3 for the coveralls (P < .01). This was a 77% and 79% reduction for both measures, respectively. CONCLUSIONS: The open nature of standard scrubs allows contaminated particles to escape into the OR environment, whereas the one-piece design of the coveralls restricts pathways of escape. The results of this study may be helpful when developing hospital infection prevention policies.

The influence of Zircos-E® etchant, silica coating, and alumina air-particle abrasion on the debonding resistance of endocrowns with three different preparation designs.

OBJECTIVES: The study aimed to evaluate the debonding resistance of three different endocrown designs on molar teeth, using three different zirconia surface pretreatments. MATERIAL AND METHOD: Ninety human mandibular first molars were divided into three main groups: endocrowns without ferrule, with 1 mm ferrule, and with 2 mm ferrule. The subgroups were defined by their surface pretreatment method used (n = 15): 50 µm alumina air-particle abrasion, silica coating using 30 µm Cojet™ particles, and Zircos-E® etching. The endocrowns were fabricated using multilayer zirconia ceramic, cemented with self-adhesive resin cement, and subjected to 5000 thermocycles (5-55°C) before debonding. The data obtained were analyzed using a two-way ANOVA. RESULTS: All test specimens survived the thermocyclic aging. The results indicated that both the preparation design and the surface treatment had a significant impact on the resistance to debonding of the endocrowns (p < .001). The 2 mm ferrule followed by the 1 mm ferrule designs exhibited the highest debonding resistance, both were superior to the endocrown without ferrule. Zircos-E® etching and silica coating yielded comparable debonding resistance, which were significantly higher than alumina air-particle abrasion. All endocrowns demonstrated a favorable failure mode. CONCLUSIONS: All designs and surface treatments showed high debonding resistance for a single restoration. However, ferrule designs with Zircos-E® etching or silica coating may represent better clinical options compared to the nonferrule design or alumina airborne-particle abrasion. Nonetheless, further research, including fatigue testing and evaluations with different luting agents is recommended.

Effect of femtosecond laser induced surface patterns on the flexural strength of monolithic zirconia.

To investigate how patterns generated by femtosecond (fs) laser and femtosecond laser power affect the surface roughness (Ra) and biaxial flexural strength (BFS) of monolithic zirconia. Eighty disk-shaped zirconia specimens were divided into eight subgroups (n = 10): Control (C), airborne-particle abrasion (APA), 400 mW fs laser (spiral [SP(400)], square [SQ(400)], circular [CI(400)]), and 700 mW fs laser ([SP(700)], [SQ(700)], [CI(700)]). Ra values were calculated by using a surface profilometer. One additional specimen per group was analyzed with scanning electron microscopy and x-ray diffractometry. BFS values were obtained by using the piston-on-3-ball test. One-way ANOVA and either Tukey's HSD (BFS) or Tamhane's T2 (Ra) tests were used to evaluate data (α = 0.05). Regardless of the pattern and power, fs laser groups had higher Ra than C and APA, while SP groups had lower Ra than CI and SQ groups (p ≤ 0.004). For each pattern, Ra increased with higher laser power (p < 0.001), while the laser power did not affect the BFS (p ≥ 0.793). CI and SQ groups had lower BFS than the other groups (p ≤ 0.040), whereas SP groups had similar BFS to C and APA (p ≥ 0.430). Fs laser microstructuring with spiral surface pattern increased the Ra without jeopardizing the BFS of zirconia. Thus, this treatment might be an option to roughen tested zirconia.

Association of pulmonary black carbon accumulation with cardiac fibrosis in residents of Sao Paulo, Brazil.

Evidence suggests that myocardial interstitial fibrosis, resulting from cardiac remodeling, may possibly be influenced by mechanisms activated through the inhalation of airborne pollutants. However, limited studies have explored the relationship between lifetime exposure to carbon-based particles and cardiac fibrosis, specially using post-mortem samples. This study examined whether long-term exposure to air pollution (estimated by black carbon accumulated in the lungs) is associated with myocardial fibrosis in urban dwellers of megacity of Sao Paulo. Data collection included epidemiological and autopsy-based approaches. Information was obtained by interviewing the next of kin and through the pathologist's report. The individual index of exposure to carbon-based particles, which we designed as the fraction of black carbon (FBC), was estimated through quantification of particles on the macroscopic lung surface. Myocardium samples were collected for histopathological analysis to evaluate the fraction of cardiac fibrosis. The association between cardiac fibrosis and FBC, age, sex, smoking status and hypertension was assessed by means of multiple linear regression models. Our study demonstrated that the association of FBC with cardiac fibrosis is influenced by smoking status and hypertension. Among hypertensive individuals, the cardiac fibrosis fraction tended to increase with the increase of the FBC in both groups of smokers and non-smokers. In non-hypertensive individuals, the association between cardiac fibrosis fraction and FBC was observed primarily in smokers. Long-term exposure to tobacco smoke and environmental particles may contribute to the cardiac remodeling response in individuals with pre-existing hypertension. This highlights the importance of considering hypertension as an additional risk factor for the health effects of air pollution on the cardiovascular system. Moreover, the study endorses the role of autopsy to investigate the effects of urban environment and personal habits in determining human disease.

Effect of airborne particle abrasion and regeneration firing on the strength of 3D-printed 3Y and 5Y zirconia ceramics.

OBJECTIVES: This study aimed to assess the effect of airborne particle abrasion (APA) and regeneration firing (RF) on the subsurface damage and strength distribution of 3D-printed 3Y-TZP and 5Y-PSZ zirconia parts for dental applications. METHODS: Disc-shaped specimens were prepared using vat photopolymerization (VPP) technology from 3Y and 5Y zirconia ceramics, followed by thermal debinding and sintering. APA treatment with 50 µm Al2O3 particles and RF at 1000 °C for 15 min were applied. Microstructural analysis was conducted using FIB-SEM, and XRD analysis determined crystalline phase content. Biaxial flexural strength was measured using the ball on three balls method and analyzed with Weibull statistics. ANOVA and Tukey HSD test were employed to compare strength differences between groups. RESULTS: APA treatment increased the flexural strength of the 3Y specimens but decreased it for the 5Y specimens. RF treatment reversed the effect, restoring the strength to as-sintered levels for both materials. APA-treated 3Y specimens exhibited characteristic strength values above 1400 MPa, attributed to phase-transformation toughening. As sintered 5Y specimens showed strength values above 600 MPa. APA treatment increased the Weibull modulus of the 5Y specimens, indicating a narrower defect size distribution. SIGNIFICANCE: The study demonstrates that the impact of APA and RF treatments on the mechanical properties and reliability of VPP-fabricated 3Y-TZP and 5Y-PSZ ceramics is comparable to conventionally prepared zirconia. VPP technology for 3D printing provides a viable approach for future manufacturing of dental restorations with potential clinical applications.

The Influence of Alumina Airborne-Particle Abrasion with Various Sizes of Alumina Particles on the Phase Transformation and Fracture Resistance of Zirconia-Based Dental Ceramics.

The surface of zirconia-based dental ceramic restorations require preparation prior to adhesive cementation. The purpose of this study was to assess the influence of airborne-particle abrasion with different sizes of alumina particles (50 µm, 110 µm, or 250 µm) on the mechanical strength of zirconia-based ceramics' frameworks and on the extent of phase transformations. A fracture resistance test was performed. The central surface of the frameworks was subjected to a load [N]. The identification and quantitative determination of the crystalline phase present in the zirconia specimens was assessed using X-ray diffraction. The Kruskal-Wallis one-way analysis of variance was used to establish significance (α = 0.05). The fracture resistance of zirconia-based frameworks significantly increases with an increase in the size of alumina particles used for air abrasion: 715.5 N for 250 µm alumina particles, 661.1 N for 110 µm, 608.7 N for 50 µm and the lowest for the untreated specimens (364.2 N). The X-ray diffraction analysis showed an increase in the monoclinic phase content after air abrasion: 50 µm alumina particles-26%, 110 µm-40%, 250 µm-56%, and no treatment-none. Air abrasion of the zirconia-based dental ceramics' surface with alumina particles increases the fracture resistance of zirconia copings and the monoclinic phase volume. This increase is strongly related to the alumina particle size.

Effect of Various Airborne Particle Abrasion Conditions on Bonding between Polyether-Ether-Ketone (PEEK) and Dental Resin Cement.

The effects of alumina particle size and jet pressure on the bond strength of polyetheretherketone (PEEK) were examined to determine the airborne particle abrasion parameters with minimal effects on PEEK and to achieve optimal bond strength, as a reference for future clinical use. An alumina particle with four particle sizes and three jet pressures was used to air-abrade PEEK. Surface roughness (Ra), morphology, chemical structure, and wettability were analyzed using a stylus profilometer, scanning electron microscope, X-ray diffractometer, and contact angle analyzer, respectively. The shear bond strength (SBS) of PEEK and dental resin cement was analyzed using a universal testing machine (n = 10). The failure modes and debonded fracture surfaces were observed using optical microscopy. Airborne particle abrasion increased the Ra and hydrophobicity of PEEK and deposited alumina residues. The SBS generally decreased after thermal cycling. A large particle size damaged the PEEK surface. The effects of different particle sizes and jet pressures on the SBS were only significant in certain groups. Adhesive failure was the main mode for all groups. Within the limitations of this study, 110 µm grain-sized alumina particles combined with a jet pressure of 2 bar prevented damage to PEEK, providing sufficient SBS and bonding durability between PEEK and dental resin cement.

Effect of airborne particle abrasion treatment of two types of 3D-printing resin materials for permanent restoration materials on flexural strength.

OBJECTIVES: This study aimed to assess the effects of airborne-particle abrasion (APA) on the flexural strength of two types of 3D-printing resins for permanent restoration. METHODS: Two types of 3D printing resins (urethane dimethacrylate oligomer; UDMA, ethoxylated bisphenol-A dimethacrylate; BEMA) constituting different components were printed. The specimen surfaces were subjected to APA using 50 and 110 µm alumina particles under different pressures. The three-point flexural strength was measured for each surface treatment group, and a Weibull analysis was performed. Surface characteristics were analyzed via surface roughness measurements and scanning electron microscopy. Dynamic mechanical analysis and nano-indentation measurements were limited to the control group. RESULTS: The three-point flexural strength according to the surface treatment was significantly lower in the UDMA group for large particle sizes and at high pressures; the BEMA group demonstrated low flexural strength for large particle sizes regardless of the pressure. After thermocycling, the flexural strengths of UDMA and BEMA significantly decreased in the group subjected to surface treatment. The Weibull modulus and characteristic strength of UDMA were higher than those of BEMA under different APA and thermocycling conditions. As the abrasion pressure and particle size increased, a porous surface formed, and the surface roughness increased. Compared with BEMA, UDMA featured a lower strain, greater strain recovery, and a negligible increase in modulus according to strain. SIGNIFICANCE: Thus, surface roughness increased with the sandblasting particle size and pressure of the 3D-printing resin. Hence, a suitable surface treatment method to improve adhesion can be determined by considering physical property changes.

Bond Strength of Sandblasted PEEK with Dental Methyl Methacrylate-Based Cement or Composite-Based Resin Cement.

Poly-ether-ether-ketone (PEEK) is commonly employed in dental prostheses owing to its excellent mechanical properties; however, it is limited by its low bond strength with dental resin cement. This study aimed to clarify the type of resin cement most suitable for bonding to PEEK: methyl methacrylate (MMA)-based resin cement or composite-based resin cement. For this purpose, two MMA-based resin cements (Super-Bond EX and MULTIBOND II) and five composite-based resin cements (Block HC Cem, RelyX Universal Resin Cement, G-CEM LinkForce, Panavia V5, and Multilink Automix) were used in combination with appropriate adhesive primers. A PEEK block (SHOFU PEEK) was initially cut, polished, and sandblasted with alumina. The sandblasted PEEK was then bonded to resin cement with adhesive primer according to the manufacturer's instructions. The resulting specimens were immersed in water at 37 °C for 24 h, followed by thermocycling. Subsequently, the tensile bond strengths (TBSs) of the specimens were measured; the TBSs of the composite-based resin cements after thermocycling were found to be zero (G-CEM LinkForce, Panavia V5, and Multilink Automix), 0.03 ± 0.04 (RelyX Universal Resin Cement), or 1.6 ± 2.7 (Block HC Cem), whereas those of Super-Bond and MULTIBOND were 11.9 ± 2.6 and 4.8 ± 2.3 MPa, respectively. The results demonstrated that MMA-based resin cements exhibited stronger bonding to PEEK than composite-based resin cements.

Investigation of the effect of different surface treatments for preventing detachment of polyetheretherketone and titanium attachment matrix housings in overdentures: An in vitro study.

Aim: The attachment matrix housing (AMH) of implant overdentures is not chemically bonded with acrylic resins. Therefore, AMH may lose due to insertion and removal forces. This study aims to investigate the effects of different surface treatments to reduce the detachment of AMH and to compare the adhesion of the AMH used in implant-supported overdentures made of different materials with the reline acrylic resin. Materials and Methods: Titanium and polyetheretherketone (PEEK) AMHs were separated into four surface treatment groups; no treatment, airborne-particle abrasion (APA) applied, universal bond (UB) applicated, APA, and UB applicated. Eight millimeters in diameter and ten millimeters tall straws were used to restrain the reline acrylic resin prepared according to the manufacturer's instructions and the resin was injected onto the surface-treated AMH. After the polymerization was completed, the universal testing machine performed the tensile bond strength (TBS) test with a fishing line passed through the acrylic resins. Statistical Analysis Used: TBS data were analyzed with two and one-way ANOVA and Tukey HSD post hoc tests (α =0.05). Results: According to the two-way ANOVA results, titanium AMHs (103.78 ± 45.98 N) showed higher TBS than PEEK AMHs (67.81 ± 28.61 N). UB applicated titanium groups showed significantly increased TBS values. Conclusions: Using titanium AMHs may be a better choice in situations where clinical aesthetic expectations are unimportant for adhesion to reline acrylic resins. The UB resin significantly increased the bonding of the titanium AMHs with reline resins. The application of UB resin to titanium housings can be easily applied in a clinical situation and can reduce the detachment of the titanium AMHs.

The Effect of Surface Treatments on Zirconia Bond Strength and Durability.

To evaluate the effects of airborne particle abrasion (APA) combined with MDP-containing resin cement, a glass-ceramic spray deposition (GCSD) method on the shear bond strengths (SBSs) and durability of 3 mol% yttrium oxide-stabilized zirconia ceramic (3Y-TZP) compared with lithium disilicate glass ceramics (LDGC). 3Y-TZP disks were randomly treated as follows: for Group APA+MDP, 3Y-TZP was abrased using 50 µm Al2O3 particles under 0.1 Mpa and bonded with MDP-containing resin cement; for Group GCSD, 3Y-TZP was treated with the GCSD method, etched by 5% HF for 90 s, silanized and bonded with resin cement without MDP. Group LDGC was bonded as the Group GCSD. X-ray diffraction (XRD), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and energy dispersive X-ray detector (EDX) were used to analyze the surface chemical and micro-morphological changes of the ceramics before bonding. The bonded ceramic specimens were randomly divided into subgroups, and the SBSs were determined before and after 10,000 thermocycling. The SBSs were analyzed with a one-way ANOVA analysis. Failure modes were determined with optical microscopy and SEM. The XRD, ATR-FTIR and XPS results identified the formation of lithium disilicate and zirconium silicate on 3Y-TZP after GCSD. The SEM micrographs revealed that 3Y-TZP surfaces were roughened by APA, while 3Y-TZP with GCSD and LDGC surfaces could be etched by HF to be porous. The APA treatment combined with MDP-containing resin cement produced the high immediate zirconia shear bond strengths (SBSs: 37.41 ± 13.51 Mpa) that was similar to the SBSs of the LDGC (34.87 ± 11.02 Mpa, p > 0.05), but, after thermocycling, the former dramatically decreased (24.00 ± 6.86 Mpa, maximum reduction by 35.85%) and the latter exhibited the highest SBSs (30.72 ± 7.97 Mpa, minimum reduction by 11.9%). The 3Y-TZP with GCSD treatment displayed the lower zirconia SBSs before thermocycling (27.03 ± 9.76 Mpa, p < 0.05), but it was similar to the 3Y-TZP treated with APA and MDP containing resin cement after thermocycling (21.84 ± 7.03 vs. 24.00 ± 6.86 Mpa, p > 0.05). The APA combined with MDP-containing resin cement could achieve the high immediate zirconia SBSs of those of the LDGC, but it decreased significantly after thermocycling. The GCSD technique could yield the immediate zirconia SBSs similar to those of LDGC before thermocycling, and long-term zirconia SBSs were similar to those of 3Y-TZP treated with APA followed by MDP-containing resin cement after thermocycling. Hence, the GCSD technique could enrich zirconia surface treatments and is an alternative to zirconia surface pretreatment for 3Y-TZP bond durability.

Methodology for the direct measurement of tire emission factors.

A reduction in air pollution is an essential step toward decreasing certain health risks in urban area populations. Road traffic is one source of this pollution and can be categorized into exhaust and non-exhaust emissions (NEE). Non-exhaust emissions include, but are not limited to, brake wear particles and Tire Road Wear Particles (TRWP). Emission Factors are often used to assess the share and the amount of vehicle exhaust and non-exhaust particles in the air. In this study, we developed an approach to measure the Emission Factors (EF) of tire Particulate Matter (PM). The approach is based an experimental method allowing for direct measurements in real conditions (on a vehicle on the road). The experimental set-up as well as the measurement protocol lead to a significant reduction in the classical biases of the on-road approach, which usually lead to a large over-estimation of the amount of PM10 and PM2.5 emitted by the tire. We observed that TRWP emissions correlate in time with the tire solicitation. A careful computation from the PM10 and PM2.5 collected by a real time particle counter enables an evaluation of the total amount of TRWP contributing to air pollution. The average results indicate an Emission Factor for PM10 4.5 times lower than the EMEP guidebook value and 42 times lower for PM2.5. This discrepancy calls for further tests to confirm the results.

Effect of Fiber Reinforcement on the Flexural Strength of the Transitional Implant-Supported Fixed Dental Prosthesis.

PURPOSE: The aim of this in vitro study was to assess the efficacy of fiber reinforcement to enhance flexural strength of the transitional implant-supported fixed dental prosthesis (TISFDP). MATERIALS AND METHODS: One hundred and forty denture acrylic resin plates (64 mm × 12 mm × 5 mm) with two 7 mm diameter holes were fabricated using heat-polymerized type (Lucitone 199) and CAD-CAM prepolymerized type (AvaDent) materials to simulate a chair-side reconstruction of the TISFDP. Specimens were divided into 7 groups (n = 10) according to the airborne-particle abrasion of titanium cylinder (Straumann) surface and locations of fiber reinforcement ribbons (Ribbond-ULTRA). No cylinder surface abrasion and no fiber added acrylate specimens were used as the controls. The prosthetic screws were hand-tightened on a custom fixture with analogs. Specimen hole and cylinder were joined using a 50:50 mixture of chemically polymerized resin (QYK-SET; Holmes Dental) and repair resin (Dentsply Sirona). Ten acrylate specimens with no holes were fabricated from each tested material and assigned as positive controls. A modified four-point bending test (ASTM standard-D6272) was conducted using a universal testing machine and a custom fixture with a crosshead speed 1 mm/min. The maximum failure loads were recorded. Data were statistically analyzed using 2-way ANOVA and the Tukey tests at α = 0.05. RESULTS: The flexural strength values ranged from 55.4 ±8.3 to 140.9 ±15.4 MPa. The flexural strength decreased significantly when fiber was attached on the titanium cylinder surface (p < 0.05). There were no statistically significant differences in flexural strength values between specimens with and without titanium cylinder surface abrasion (p > 0.05). Statistically significant improvement in flexural strength was observed in specimens with fibers attached around the specimen holes (p < 0.05) buccally and lingually. The obtained values were not statistically significantly different from the positive controls (p > 0.05). Some fixation screw fractures were observed before catastrophic failure of specimens during testing. CONCLUSIONS: Fiber reinforcement significantly improved the flexural strength of denture acrylic resins only if placed around the specimen holes on the tension side at the site of initiation of crack propagation. Even when the specimens underwent catastrophic failure, the segments remained attached to each other with the attached fibers.

Effects of Surface Pretreatments on Bond Strength and Morphology of Aprismatic Enamel.

PURPOSE: To evaluate the effect of different pretreatment protocols and adhesives on the shear bond strength and surface morphology of aprismatic enamel. MATERIALS AND METHODS: Human maxillary incisors (N = 120) were assigned to five different groups according to pretreatment: 1) no treatment; 2) glycine; 3) sodium bicarbonate; 4) Al2O3 and 5) extra-fine bur. Then the teeth were divided into three subgroups, according to the adhesive applied: 3-step etch-and-rinse (ER), universal adhesive in ER mode, and universal adhesive in self-etch (SE) mode. Shear bond strength (SBS) testing was performed with a universal testing machine. For SEM observation, fifteen human molars were collected and analyzed after pretreatment with/without etching with 37% H3PO4 for 30s. RESULTS: Al2O3 showed higher SBS than all other groups considered. Comparable SBS values were obtained for other pretreatments. Universal adhesive in E&R mode performed better than did 3-step E&R and universal adhesive in SE mode. SEM images showed visible differences in enamel surface roughness. CONCLUSIONS: Airborne-particle abrasion with Al2O3 followed by etching with H3PO4 increased SBS on aprismatic enamel. The combination of airborne-particle abrasion with alumina powder followed by 15 s of H3PO4 etching and application of a universal adhesive in E&R mode proved to be the most effective adhesive protocol.

Effect of Different Surface Treatments on Repair Bond Strength of CAD/CAM Resin-Matrix Ceramics.

The purpose of this study was to investigate the influence of different surface treatment methods on the micro-tensile bond strength (µTBS) of resin-matrix ceramic (RMC) blocks repaired with resin composite. Three different prefabricated RMC blocks including Lava Ultimate (LU), Grandio Blocs (GB), and Shofu Block HC (HC) were thermo-cycled and divided into five surface treatment groups: Control (C), bur grinding (G), airborne particle abrasion (APA), Er,Cr:YSGG laser irritation (LI), and APA combined with LI (APA+LI). After surface treatments, topographic alterations were examined by scanning electron microscopy. Then, Universal Adhesive (Single Bond Universal) was applied and repair was simulated with nanohybrid composite (Grandio SO). Bonded specimens were cut into 1 mm2 sized beams (n = 16) and a µTBS test was conducted by using a universal test machine. Fracture types were evaluated by using a stereomicroscope. The bond- strength data was evaluated by two-way ANOVA and Tukey post-hoc test (α = 0.05). The µTBS values were significantly affected by the surface treatment variable and the interaction terms of the variables (p ≤ 0.001). However, no significant effect of RMC type was detected (p > 0.05). Among all materials, GBAPA+LI indicated the highest µTBS value. Except for the GBC, all surface treatments showed clinically acceptable bond-strength values. However, the surface treatments applied to GB and LU before the repair processes increased the repair bond-strength values while causing a negative effect for HC. In addition, LI and APA+LI can be applied as an alternative route compared to other procedures recommended by the manufacturer for surface preparation in intraoral RMC repair.

Prevention of droplet dispersal with 'e-mask': A new daily use endoscopic mask during bronchoscopy.

BACKGROUND AND OBJECTIVE: Bronchoscopy is an airborne particle-generating procedure. However, few methods for safe bronchoscopy have been developed. To reduce airborne particles during bronchoscopy, we created an 'e-mask', which is a simple, disposable mask for patients. Our objective was to evaluate the e-mask's protective ability against airborne particles and to assess respiratory adverse events and complications. METHODS: Patients with stage 2-4 chronic obstructive pulmonary disease were excluded. We performed visualization and quantifying experiments on airborne particles with and without the e-mask. We prospectively evaluated whether wearing the e-mask during bronchoscopy was associated with the incidence of patients requiring >5 L/min oxygen to maintain >90% oxygen saturation, and patients with >45 mm Hg end-tidal carbon dioxide (EtCO2 ) elevation, in addition to complications, compared to historical controls. RESULTS: In the visualization experiment, more than ten thousand times of airborne particles were generated without the e-mask than with the e-mask. The volume of airborne particles was significantly reduced with the e-mask, compared to that without the e-mask (p = 0.011). Multivariate logistic regression analysis revealed that wearing the e-mask had no significant effect on the incidence of patients requiring >5 L/min oxygen to maintain >90% oxygen saturation, (p = 0.959); however, wearing the e-mask was a significant factor in >45 mm Hg EtCO2 elevation (p = 0.026). No significant differences in complications were observed between the e-mask and control groups (5.8% vs. 2.5%, p = 0.395). CONCLUSION: Wearing the e-mask during bronchoscopy significantly reduced the generation of airborne particles during bronchoscopy without increasing complications.