Ceramic Cement Research Articles

Injectable biocomposite cement: A dual-setting formula with magnesium potassium phosphate and κ-carrageenan hydrogel for orthopedic advancements

Magnesium phosphate-based cements are highly regarded for their bioactive properties, making them excellent candidates as bone substitutes. Despite their promising attributes, challenges such as high reaction temperature, limited injectability, and brittleness limit their application. This study introduces a dual-setting biocomposite cement, which encompasses both cement hydration and hydrogel's cross-linking. The composition features magnesium potassium phosphate (MKP) combined with ionically cross-linked kappa-carrageenan (kC) plasticized with sorbitol (Sor). The investigation delves into the properties of the resultant biocomposite, with a particular focus on evaluating kC incorporation's influence on the main MKP properties. Our findings reveal that those biocomposites offer multiple benefits over traditional ceramic cements. The main advantages include: a longer setting time (up to ~15 min), lower setting temperature (~45 °C), different crystalline phase (bobierrite), better wettability (~22°), and improved injectability of the paste characterized by more stable cohesion. Specifically, the MKP (4:1 Mg/P ratio) with 1.5 % kC and Sor hydrogel obtained with 3.0 g/mL powder-to-liquid ratio demonstrated the most promising properties with no adverse effects on the microstructure diversity, the mechanical strength, the porosity, the biodegradation rate, and the osteoblasts cytocompatibility. Overall, our research indicates that these innovative cements hold significant potential for biomedical applications, especially minimally invasive orthopedic procedures.

Effects of porcelain layer thickness and luting resin cement on the opalescence properties of porcelain veneers

BackgroundWhen discolored teeth are repaired with porcelain veneers, the thickness of the restorations should be increased appropriately using opaque porcelain and bonded by applying opaque luting resin cement to cover discolored substrates. However, its impact on the opalescent performance has not been reported yet.PurposeTo analyze the effects of opacity, body porcelain layer thickness, and luting resin cement on the opalescence properties of porcelain veneer restorations for discolored teeth.MethodsNinety IPS d. SIGN A3 porcelain veneer specimens were prepared via powder–paste coating and sintering. Specimens were divided into three groups according to ceramic type and cement used or not: body porcelain group as control, body/opaque porcelain group and body/opaque porcelain–resin cement composite group. Each group was subdivided into three subgroups based on the thickness, 0.50, 0.75, and 1.00 mm (n = 10). Variolink N Bleach XL luting resin cement with thickness of 0.1 mm was applied to the bottoms of body/opaque porcelain specimens to produce body/opaque porcelain–resin cement composites. The opalescence (OP) values were calculated and the micromorphological characteristics were analyzed by scanning electron microscope (SEM). Statistical analysis was performed by using ANOVA test (P < 0.05).ResultsThe opalescence values determined for the body porcelain groups with thicknesses of 0.50, 0.75, and 1.00 mm and body/opaque porcelain specimens with thicknesses of 0.45/0.05, 0.70/0.05, and 0.95/0.05 mm were 3.35 ± 0.15, 3.83 ± 0.10, 6.73 ± 0.25, 7.95 ± 0.34, 15.16 ± 0.60, and 16.49 ± 0.89, respectively. The specimens in the body and body/opaque porcelain groups exhibited significant increases in their opalescence values with increasing thickness (P = 0.00). The opalescence values of the specimens increased significantly with the addition of a 0.05 mm opaque porcelain layer (P = 0.00). The opalescence values of the composites containing body/opaque porcelain layers with thicknesses of 0.45/0.05, 0.70/0.05, and 0.95/0.05 mm and luting resin cement were 9.46 ± 0.17, 16.47 ± 0.15, and 18.38 ± 0.47, respectively. The opalescence values of the composite specimens increased significantly with an increase in the thickness of the porcelain layer(P = 0.00).ConclusionsThe opaque porcelain layer and opaque resin cement can significantly improve the opalescence properties of porcelain laminate veneers for discolored teeth, but the opalescence performance is still poor than natural teeth. The body porcelain only contributes to opalescence within a certain thickness range.

Influence of Ceramic Waste and Cement on the Mechanical and Hydraulic Properties, and Microstructure of the Road Sub-Base Layer

This study examines cement and ceramic waste (CW) for the sub-base layer of roads. This innovative method can do away with the risks associated with improper disposal of industrial waste. To achieve this objective, several proportions of cement and CW were used, ranging from 1.5 to 2% and 5% to 15%, respectively. The aim of the work was to examine the influences of CW and ordinary Portland cement (OPC) on the unconfined compressive strength (UCS), permeability, consolidation, and microstructures of untreated and treated soil of road sub-base layer. The Guelph permeameter, UCS, permeability, and one- dimensional consolidation were among the laboratory and in-situ tests that were examined; the microstructures were characterised using SEM, infrared (IR), and mercury intrusion porosimetry (MIP). The findings indicated that the high permeability of the natural soil caused harm to our road soon after construction. Applying 5 to 15% CW reduced permeability by approximately 100% and settlement by around 43%. Furthermore, under wet and immersed conditions, mixing CW and OPC with soil raised UCS by approximately 182% and 20 times, respectively. This study demonstrated that by enhancing the geotechnical properties of soil, CW and OPC combined with it could be used as a road sub-base layer material.

Injectable bone cement based on magnesium potassium phosphate and cross-linked alginate hydrogel designed for minimally invasive orthopedic procedures

Bone cement based on magnesium phosphate has extremely favorable properties for its application as a bioactive bone substitute. However, further improvement is still expected due to difficult injectability and high brittleness. This paper reported the preparation of novel biocomposite cement, classified as dual-setting, obtained through ceramic hydration reaction and polymer cross-linking. Cement was composed of magnesium potassium phosphate and sodium alginate cross-linked with calcium carbonate and gluconolactone. The properties of the obtained composite material and the influence of sodium alginate modification on cement reaction were investigated. Our results indicated that proposed cements have several advantages compared to ceramic cement, like shortened curing time, diverse microstructure, increased wettability and biodegradability and improved paste cohesion and injectability. The magnesium phosphate cement with 1.50% sodium alginate obtained using a powder-to-liquid ratio of 2.5 g/mL and cross-linking ratio 90/120 of GDL/CC showed the most favorable properties, with no adverse effect on mechanical strength and osteoblasts cytocompatibility. Overall, our research suggested that this novel cement might have promising medical application prospects, especially in minimally invasive procedures.

Assessment of Novel Surgical Procedures Using Bone Morphogenic Protein-7 Infused Into Decellularised Muscle and Bioactive Ceramic: A Histological Analysis.

Reconstruction of critical bone defects is considered a challenge due to vascular reperfusion injury that may occur. The present study hypothesized that the use of decellularized muscle scaffold (DMS) and bone morphogenic protein-7 (BMP-7), along with resorbable bioactive ceramic silica calcium phosphate cement (SCPC) seeded with human bone marrow stromal cells, can expedite bone formation and maturation. Surgical bone defects were created in 20 nude transgenic mice. In experimental group 1 (n = 10), a critical-size (4mm) calvarial defect was made and grafted with DMS-BMP-7/SCPC. In situ human bone marrow stromal cells [human mesenchymal stromal cells (hMSC)] were seeded thereafter. As a control, group 2 (n = 10) was treated with DMS/SCPC seeded with hMSCs. After 8 weeks, bone regeneration was evaluated using histology and histomorphometry for both groups. Histological examination showed bone regeneration crossing the gap (experimental group 1), bone regeneration was noted at the defect periphery, and scattered islands of bone at the canters of the defects (control group 2). New bone formation and maturation were superior in the groups treated with the DMS/BMP-7/SCPC/hMSC constructs. The quantitative histological assessment revealed that the average bone surface area was 255 ± 25mm2, which was 1.5 times the surface area of group 2, which was reported at 170 ± 35mm2. The reported difference was considered statistically significant (P < 0.05). The DMS-BMP-7/SCPC scaffold induced bone regeneration and neovascularization in critical-size defects.

Nanophase and nanostructure of tungsten carbide: The electrical explosion of a wire in a solid matrix of naphthalene and carbon nanotube

Tungsten carbides are important materials used in ceramic cements, machining tools, catalysts, sensors, and for hydrogen generation. Bulk W–C structures are highly complex; fundamental fully carburized WC and semi-carburized W2C are accompanied by structural transitions depending on the composition and temperature. The relationship between the structures, compositions, and temperatures is summarized in the W–C phase diagram. However, the high-temperature, stable, and single-crystalline nanoparticles related to the WC1-x and W2C phases formed via energetic reactions accompanied by rapid cooling rates are not easy to determine considering the bulk phase diagram, and lead to fundamental questions regarding the origin of the nanophases. In this study, we propose a draft for the W–C nanophase diagram composed of the surface and gas-phase WC, WC1-x, and W2C nanophases according to the composition and temperature. The model undergoes the process of a vapor–nanoliquid–nanophase starting from the gas-phase nucleation induced by an extremely high-temperature electrical explosion. In addition, the high-temperature reactivity and quenched nanophase, including its unique nanostructure, are related to the post-melt rheology, physical morphology, and steric hindrance of the solid matrix during an electrical explosion.

Thermodynamic descriptions of the CaO–Al2O3 and CaO–Al2O3–SiO2 systems over the whole composition and temperature ranges

AbstractThe CaO–Al2O3–SiO2 system is a fundamental system in aluminosilicate materials, and its thermodynamic description provides key information for ceramic design, cement production, slag tapping, and geological prediction. However, the existing thermodynamic calculations for the CaO–Al2O3 system show inaccurate heats of formation for the compounds and consequently a decomposition of the CA2 (CaO⋅2Al2O3) phase at a low temperature. Besides, the solid solutions in anorthite and cristobalite have never been considered in the previous thermodynamic assessments for the CaO–Al2O3–SiO2 system. Therefore, thermodynamic reassessments of the CaO–Al2O3 and CaO–Al2O3–SiO2 systems are carried out in the present work using the CALculation of PHAse Diagram method, considering the solid solution in anorthite and cristobalite for the first time. The anorthite and cristobalite phases are modeled based on the individual mechanism of solid solution, with the anorthite described by (Ca+2, Va)1(Al+3, Si+4)2(Si+4)2(O−2)8 and the cristobalite described by (Va, Ca+2)1(Si+4, Al+3)2(O−2)4. The present assessment solves the above issues and provides consistent thermodynamic descriptions for the liquid and solid phases. Based on the established thermodynamic database, a Scheil solidification simulation is carried out for a cement clinker and the variations of mass fractions of the phases as well as the composition of liquid during Scheil cooling are calculated. The present work guides the design of relevant materials and lays an essential foundation for the establishment of the thermodynamic database of multicomponent aluminosilicate materials.

Pozzolanic performance and characteristic analysis of binary blended cement incorporating ceramic polishing sludge

The waste generated during ceramic polishing is typically disposed of in landfills rather than being recycled within the production facility, potentially causing environmental harm. This study aims to enhance industrial waste utilization and reduce CO2 emissions in the cement industry by investigating the feasibility of incorporating ceramic sludge from polishing processes into an innovative binary blended cement. Different binders were prepared with varying amounts of ceramic polishing sludge (CPS), ranging from 10% to 50%, and tested against the ASTM C595 standards. The results were compared with those of ordinary Portland cement (OPC). This approach involves evaluating the pozzolanic activity and conducting an advanced characterization assessment of CPS and binary blended ceramic polishing sludge cement (CPSC) paste. This study employed a combination of physical, mechanical, and chemical tests, including setting time, particle size distribution (PSD), Brunauer-Emmett-Teller (BET) specific surface area, compressive strength, X-ray diffraction (XRD), scanning electron microscopy (SEM), heat of hydration, and differential scanning calorimetry/thermogravimetric analysis (DSC/TGA). The results indicated that CPS can be used as a pozzolanic material to create innovative binders with properties comparable to those of OPC. The Strength Activity Index (SAI) values affirmed the pozzolanic properties of CPS, exceeding 75% for up to 40% CPS replacement. Incorporating CPS in the blended cement resulted in a slower rate of cement hydration, leading to prolonged setting times and reduced early strength development. Although the compressive strength decreased with increasing CPS content, it remained within the acceptable ASTM C595 limits with up to 50% replacement. Nevertheless, the optimal replacement level of OPC with CPS was determined to be 50%. Furthermore, CPS substitution reduced the dry density and improved the water absorption and apparent porosity, reflecting microstructural changes. The SEM images revealed that the blended CPSC had a lower apparent porosity than the pure OPC. The DSC/TGA analysis demonstrated that the blended cement had a lower calcium hydroxide content and higher silica than pure OPC.

Physicochemical properties of calcium silicate cement based endodontic sealers

AimTo mensure the physicochemical properties of three ceramic cement endodontic sealers AH Plus Bioceramic, Bio-C Sealer and Bio-C Sealer Ion+ with an epoxy resin sealer, AH Plus. Material and methodsThese properties were measured: hardening time (HT), dimensional change (DC), solubility (SL), flow (FL) and radiopacity (RD). The distilled water obtained from the SL test was analyzed with atomic absorption spectrometry. A sample calculation was made considering n = 5 repetitions for each experimental sealer evaluated. Statistical analysis was performed using one-way ANOVA and post hoc Tukey tests (p < 0.05). ResultsFor the HT, AH Plus (484 ± 2.76 min) and AH Plus Bioceramic (424 ± 1.23 min) set more slowly than of Bio-C Sealer (370 ± 4.50 min) and Bio-C Sealer Ion+ (380 ± 1.42 min) (p < 0.05). AH Plus Bioceramic (12.56 ± 2.71 %) was more soluble than Bio-C Sealer (6.69 ± 1.67 %), Bio-C Sealer Ion+ (5.67 ± 2.16 %) and AH Plus (0.15 ± 0.01 %) (p < 0.05). AH Plus (0.03 ± 0.01 %) had slight expansion while the cement-based sealers had shrinkage: AH Plus Bioceramic (−1.60 ± 0.63 %) and Bio-C Sealer (−1.38 ± 0.69 %), Bio-C Sealer Ion+ (−5.19 ± 1.23 %) (p < 0.05). Bio-C Sealer Ion+ (59.80 ± 0.86 mm) and Bio-C Sealer (58.60 ± 0.98 mm) had the highest flow compared with AH Plus (56.90 ± 0.56 mm) and AH Plus Bioceramic (49.50 ± 0.63 mm) (p < 0.05). AH Plus (9.17 ± 0.06 mmAl) and AH Plus Bioceramic (8.27 ± 0.84 mmAl) showed radiopacity values when compared with those of Bio-C Sealer (4.90 ± 0.08 mmAl) and Bio-C Sealer Ion+ (4.14 ± 0.05 mmAl) (p > 0.05). ConclusionIon release is inhered to these cement-based sealers and this result in calcium ion release.

Effect of Surface Treatment and Resin Cement on the Bond Strength of an Advanced Lithium Disilicate.

The aim of the study was to evaluate the effect of surface treatment and resin cement on the bond strength of conventional and advanced lithium disilicates (ALDs). Ceramic slices (2 × 13 × 15 mm) of conventional lithium disilicate (LD) (IPS e.max CAD) and ALD (CEREC Tessera) were sectioned, polished, and divided into 16 groups (n = 10) according to the factors: ceramic, surface treatment, and resin cement (Panavia V5 and Variolink Esthetic DC). Surface treatments consisted of hydrofluoric acid 4.9% etching for 20 seconds (Hf20) or 30 seconds (Hf30), self-etching ceramic primer (Se), and sandblasting (Sb). Then, a resin cement cylinder (Ø = 2.5 mm) was manufactured on each specimen's surface. The specimens were then submitted to a shear bond strength (SBS) test. Surface roughness was evaluated through a contact profilometer, and surface morphology was evaluated under scanning electron microscopy for qualitative analysis. Two-way analysis of variance (ANOVA) was used to analyze the data of SBS and surface roughness. For bond strength, the effects of surface treatment, resin cement, and the interaction were analyzed for each ceramic. For roughness, analyzed factors include ceramic and surface treatment. ANOVA revealed that ceramic (p = 0.047) and surface treatment (p < 0.001) factors affected the bond strength, while the cements performed similarly. Both materials showed adequate bond strength (ALD 19.1 ± 7.7 MPa; LD 17.1 ± 7.9 MPa). Sb protocol showed the lowest mean value (9.6 ± 2.9 MPa) compared with Hf20 (22.0 ± 7.1 MPa), Hf30 (21.7 ± 7.4 MPa), and Se (19.3 ± 6.0 MPa). For both ceramics, the highest performance was obtained after applying Se and Hf20 or Hf30. Therefore, longer etching time is unnecessary. Sb protocol must be avoided.

Influence of Ceramic Material Type and Cement Shade on the Translucency of Lithium Disilicate Ceramic Veneers.

Aims: Careful selection of materials and resin cement shade can minimize color changes in laminate veneers. This study aimed to evaluate the influence of two ceramic material types, lithium disilicate glass-ceramic material (Ivoclar, Schaan/Liechtenstein; IPS e.max), computer aided design (CAD) and IPS e.max Press, and four different resin cement shades on color changes in lithium disilicate ceramic laminate veneers. Methods: Forty extracted human maxillary first premolars were prepared to receive a laminate veneer. Optical scanning and digital designing were used to prepare 20 IPS e.max CAD and 20 IPS e.max Press veneer samples. These samples were divided into four groups based on resin cement shade and material: Group CAD A1 : (IPS e.max CAD with A1 cement shade), Group CAD T : (IPS e.max CAD with translucent cement shade), Group CAD M : (IPS e.max CAD with milky bright cement shade), Group CAD B1 : (IPS e.max CAD with B1 cement shade) and the same divisions for IPS e.max Press. Before cementation, color measurements were obtained using precision colorimeter NR110. After cementation, the ∆E (color change) value was recorded and tabulated. One-way analysis of variance (ANOVA) and Duncan's post hoc test were used to evaluate the influence of ceramic material types and cement shade on ∆E. Results: There were significant differences between the IPS e.max CAD and e.max Press veneers for the four tested cement shades. The highest color change was observed in press M veneers (8.84 ± 0.63931) while the lowest color change was observed in CAD M veneers (0.5 ± 0.16371). There were significant differences in color change based on cement shade, with B1 showing the greatest change (8.84 ± 0.47440 for Press veneers and 2.3 ± 0.11992 for CAD veneers). Conclusions: Different shades of resin cements and different manufacturing techniques produce different levels of color changes therefore careful selection of materials and cement shade can minimize color changes in laminate veneers.

Effect of Self-Adhesive Resin Cement Film Thickness on the Shear Bond Strength of Lithium Disilicate Ceramic–Cement–Tooth Triplex

Cement film thickness may have an impact on the shear bond strength (SBS) of lithium disilicate dental ceramics luted to human enamel with resin cement. The objective of this study was to evaluate SBS of lithium disilicate ceramics adhered to enamel using resin cement at different thicknesses. In total, 50 ceramic specimens (3 × 3 × 3 mm) and 50 premolar teeth were prepared and randomly assigned to 5 groups (n = 10 each). Ceramic specimens were designed with five cement film thicknesses (50 μm; 100 μm; 150 μm; 200 μm; and 300 μm). Teeth surfaces (4 × 4 mm) were prepared with a high-speed handpiece mounted on a dental surveyor. Ceramic specimens were cemented to teeth with resin cement (3MTM RelyXTM U200, Resin-Self-Adhesive-Cement). The specimens were then thermocycled for 6000 cycles with a 30 s dwell time and a 5 s transfer time in water (5 °C and 55 °C). A Universal-Testing-Machine was used to measure SBS (MPa). Statistical analysis in SPSS included Anova and Tukey’s tests. The SBSs of ceramics adhered to teeth revealed significantly different values across all test groups (p = 0.000). The findings showed that as cement layer thickness increased, so did the SBS. The cement spaces at 50 and 300 μm had the lowest SBS (9.40 + 1.15 MPa) and maximum SBS (21.98 + 1.27 MPa), respectively. The SBS of the lithium disilicate ceramic luted to natural human enamel increased along with the cement layer thickness.

A comprehensive study on the fire resistance properties of ultra-fine ceramic waste-filled high alkaline white cement paste composites for progressing towards sustainability

The most practical sustainable development options to safeguard the local ecology involve reducing the use of raw materials and guaranteeing proper recycling of the principal destroyed solid wastes. Preventing the creation of hazardous waste and the subsequent pollution that results from improper disposal is a top priority. Based on this, the study's authors recommend reusing the ultra-fine ceramic shards (CW). High-alkaline white cement (WC) has been partially replaced by ultra-fine CW because it is a cheaper, more abundant, and more lasting environmental material used in the production of trendy blended white cement pastes composites. In this context, we look at ultra-fine CW, a material that has been suggested for use as a hydraulic filler due to its high performance, physicomechanical qualities, and durability. XRF, XRD, FTIR, and SEM measurements are used to characterize the microstructure, thermal characteristics, and thermodynamics. Because of the effect of ultra-fine ceramic waste, the firing test reduces the mechanical strength by default, but with active filler, decreases slowly and increase its physicomechanical features and compressive strength compared to the control sample (WC), setting a new benchmark. The maximum amount of crystallization formed in the presence of ultra-fine ceramic waste in WC-matrix, resulting in a decrease in total porosity and early cracking. Together, the improved workability and energy-saving features of cement blends with ultra-fine ceramic waste, reflect their economic and environmental benefits, which may reduce building costs and boost the durability of the raw materials used in the mix.

Adhesive bond strength of monolithic zirconia ceramic finished with various surface treatments.

This study aimed to investigate different surface treatments thought to increase the bond strength between zirconia ceramic and adhesive resin cement. The samples were prepared in 15 × 10 × 2mm dimensions by cutting off monolithic zirconia ceramic blocks (Incoris TZI; Sirona, Germany). Surface roughness measurements were made with a profilometer, the average surface roughness (Ra1) was recorded, and five different surface treatments were applied. Group 1: Control group. No surface treatment was applied. Group 2: Sandblasted with Al2O3 under pressure of 50μm. Group 3: Sandblasted with 30μm Al2O3 - SiOx under pressure, then tribochemical silica coating, silane bonding agent, and ceramic primer were applied. Group 4: Samples were etched in a hot acid solution containing methanol, HCl, and chloride at 100°C. Group 5: Samples were coated in a solution containing Grade C Aluminum Nitrite at 75°C for 15 Sects.12,000 thermal aging was carried out to all samples. Then, samples were bonded to a composite surface (Filtek Z250) with two different types of adhesive cement (Panavia F 2.0, Rely X U200) (n = 10). A load was applied to the samples attached to the Universal Test Device for the SBS, and the SBS was recorded. The surface roughness measurements of all samples were made again, and the average surface roughness Ra2 was recorded. The data was analyzed with a two-way ANOVA test. Bonferroni correction was used for multiple comparisons of the groups. p = 0.005 was accepted as the statistically significant value. There was no statistically significant difference between the groups in the Ra1 measurements (p = 0.031). There was a statistically significant difference between the Ra2 values of Groups 4 and 5 and the Ra2 values of Groups 1,2 and 3 in the Ra2 measurements (p < 0.001). There was no statistically significant difference between the SBS values of the groups (p > 0.005). Also, there was no statistically significant difference in the SBS values of all groups for the two different cements tested (p > 0.005). None of the surface treatments applied to monolithic zirconia ceramic samples increased the SBS between ceramic and adhesive resin cement.

Masking capacity of minimally invasive lithium disilicate restorations on discolored teeth-The impact of ceramic thickness, the material's translucency, and the cement color.

To evaluate minimally invasive restorations' capacity to mask discolored teeth and explore the impact of ceramic thickness, translucency, and cement color. Twenty-four assessment pairs of naturally colored and discolored bovine dentin samples were formed, using lithium disilicate specimens in six different thicknesses (0.3-0.8 mm), two different translucencies (high, low), and two cements (transparent, tooth-colored). Evaluators assessed the color differences in each assessment pair, and the threshold for detecting a color difference was determined using sequential testing and the Bonferroni-Holm method. A thickness of 0.6 mm effectively masked color differences using high translucent ceramic with transparent cement, detectable differences were still observed at 0.7/0.8 mm. A threshold thickness of 0.4 mm was seen using high translucent ceramic and tooth-colored cement, with color differences still discernible at 0.5 and 0.8 mm. A threshold thickness of 0.4 mm was detected using low translucent ceramic and transparent cement, while detectable differences persisted at 0.5, 0.7, and 0.8 mm. A 0.5 mm threshold thickness was observed when using low translucent ceramic and tooth-colored cement, and no detectable color differences were detected beyond this thickness. Masking can be achieved with a thickness of 0.4-0.5 mm using a low translucent material and tooth-colored cement. Understanding the impact of ceramic thickness, translucency, and cement color can aid clinicians in making informed decisions for achieving the best esthetic outcomes while preserving tooth structure. Effective masking can be accomplished with ceramic thicknesses starting at 0.4 mm, especially when employing a low translucent material and tooth-colored cement. However, clinicians should be aware that discolorations may still be detectable in certain scenarios when using minimally invasive lithium disilicate restorations.

Influence of Mono- and Multiwave Light-curing Units on the Microhardness and Degree of Conversion of Light-cured Resin Cements.

This study evaluated the Knoop hardness (KH, N/mm2) and degree of conversion (DC, %) on the margins of light-cured resin cements with different photoinitiators using a single light-curing unit (LCU) with two heads (mono- and multiwave). Three types of resin cements were used with different photoinitiators: Megalink Esthetic (Odontomega, São Paulo, Brazil) with a camphorquinone photoinitiator; Allcem Veneer (FGM, Joinville, Brazil) with the Advanced Polymerization system (APS), and Variolink Esthetic LC (Ivoclar Vivadent, Schaan, Liechtenstein). Thirty samples were collected and divided into six groups (n=5 each). The resin cement samples were made into the shape of a maxillary right central incisor and photoactivated under a 0.5-mm-thick ceramic sheet. A single LCU (Radii Xpert, SDI) with two heads (mono- and multiwave) was used. The tip of the LCU was positioned at the center of the sample in a standardized manner. Raman spectroscopy was performed to evaluate the DC, and KH was evaluated through the Knoop microhardness test. Five regions were evaluated: cervical, mesial, buccal (center), distal, and incisal. There was a significant difference in the DC only for the type of cement (p<0.001), indicating that the cement with the APS photoinitiator presented excellent results. There were significant differences in the type of cement (p<0.001), type of light (p<0.001), region (p<0.001), and the interaction between the type of cement and type of light (p<0.001). The resin cement with the APS photoinitiator cured with monowave light showed the highest KH values. The beam profiles of all groups, with and without the interposition of ceramic and resin cement, were examined by light transmission. The cement with the APS photoinitiator presented the best results with respect to the DC and KH. In comparison with mono- and multiwaves, the LCU may not be a determining factor for the properties of light-cured resin cements. The buccal region showed the best results for DC and KH, indicating the need for a greater amount of light-curing at the cementation margins.

Chemomechanical Properties and Biocompatibility of Various Premixed Putty-type Bioactive Ceramic Cements

IntroductionThis study aimed to evaluate the chemomechanical properties and biocompatibility of recently introduced premixed putty-type bioactive ceramic cements (PPBCs). MethodsIncluding ProRoot MTA (PMTA) as a control, BC RRM fast-set putty (BCPT), Well-Root PT (WRPT), One-Fil PT (OFPT), and Endocem MTA premixed (ECPM) were compared to evaluate setting time, radiopacity, pH change, and microhardness. Biocompatibility on human dental pulp cells was compared using CCK-8 assay. Mineralization potential was evaluated using alkaline phosphatase activity, Alizarin Red S (ARS) staining, and quantitative real-time polymerase chain reaction with odontogenic gene marker. For data analysis, 1-way analysis of variance and Tukey's post hoc test were used at the significance level of 95%. ResultsAmong the PPBCs, BCPT presented the longest (552 ± 27) setting time (minutes) and others showed significantly shorter time than PMTA (334 ± 22) (P < .05). WRPT (6.20 ± 0.54) and OFPT (5.82 ± 0.50) showed significantly higher radiopacity values (mmAl) and others showed similar value compared with PMTA (P > .05). All PPBCs showed high alkaline pH from fresh materials and tended to increase according to time periods from 30 minutes to 12 hours. ECPM showed the highest value of microhardness (81.62 ± 5.90), WRPT showed similar, and others showed lower than PMTA (P < .05). All PPBCs showed biocompatibility in CCK-8 assay. All PPBCs showed similar or better value compared with PMTA in ALP and ARS staining, and ALP and DSPP marker expression (P < .05). ConclusionsThe PPBCs showed clinically acceptable chemomechanical properties and favorable mineralization potential.

Irradiation of ultrasonic sensors and adhesive couplants for application in light water reactor primary loop piping and components

The Electric Power Research Institute (EPRI) Nuclear Sector and US Department of Energy Light Water Reactor Sustainability Program are committed to engaging in research and development endeavors to address materials aging issues specific to long term operation of light water power reactors. To this effect, EPRI launched an industry initiative to develop nondestructive evaluation systems for online monitoring of existing cracks in light water reactor primary coolant loop piping and components. One of the goals of this initiative is to develop a sensor system (or systems) that can determine nondestructively if cracks are growing or arrested and, in the case of the former, to characterize their growth rates. A missing component of this initiative is an experimental assessment of how sensors and adhesive couplants will perform in service when exposed to chronic energetic neutron radiation, particularly at the primary coolant loop hot and cold leg dissimilar metal welds, which join the primary loop piping to the reactor pressure vessel and reside in the vicinity of the reactor core. The objective of this experimental study was to determine how ultrasonic transducers and adhesive couplants perform when exposed to irradiation in a test reactor to simulate and accelerate in-service exposure. To achieve this objective, the signal stability of piezoelectric transducers and performance of adhesive couplants as a function of accumulated fast neutron fluence were characterized by collecting ultrasonic data in-situ during irradiation. Of particular interest were the ultrasonic signal quality and time decay of the amplitude of acoustic reflections as a function of fast neutron fluence. The results of the study showed that, of the 8 transducer/substrate sample assemblies tested, only 3 generated usable ultrasonic signals through the conclusion of the irradiation campaign. It was found that high temperature epoxy tends to ultrasonically couple the sensors to the substrates better than three types of refractory ceramic cements studied, as is supported by post irradiation examination. The results obtained through this experimental study will be utilized in the achievement of the overall goal of development of a sensor system to perform online monitoring of primary loop components.This manuscript has been authored in part by UT-Battelle, LLC, under contract DE AC05-00OR22725 with the US Department of Energy (DOE). The publisher acknowledges the US government license to provide public access under the DOE Public Access Plan (https://energy.gov/downloads/doe-public-access-plan [energy.gov]).

Comparative study of the bond strength of ZirCAD Multi and ZirCAD Prime ceramics with different types of cements

Zirconia ceramic is a modern material used for different types of prosthetic constructions, characterized by high mechanical resistance and aesthetics. The main difficulties in treatment are related to ensuring a stable and durable bond between the ceramic and dentin. This study examined the bonding strength of ZirCAD Multi (3rd generation) and ZirCAD Prime (5th generation) ceramics when using different types of cements before and after sandblasting the surface of zirconia with Al2O3. For this purpose, an experimental setup was created by 3D printing, in which sintered ceramic cylinders were cemented to dentin slices of natural teeth with different types of cements. From the formed ceramic-dentin constructions, test specimens were cut with a microtome and tested for tensile strength. The results showed an increase in the strength of the bond after sandblasting from 1.1 MPa to 2.4 MPa for ZirCAD Multi and from 1.6 MPa to 3.3 MPa for ZirCAD Prime. Zirconia ceramic ZirCAD Prime (5th generation) showed higher adhesion resistance, with the strongest bond being with the Speed Cem Plus and Panavia V5 cements. With ZirCAD Multi, the maximum tensile strength was achieved with the Rely X Luting Plus and Speed Cem Plus cements. Optimal strength and bond resistance were registered between the new fifth-generation zirconia ceramic and composite cements with MDP (10-methacryloyloxydecyl dihydrogen phosphate) primers.

Effect of Ceramic and Dentin Thicknesses and Type of Resin-Based Luting Agents on Intrapulpal Temperature Changes during Luting of Ceramic Inlays.

The adhesive cementation of ceramic inlays may increase pulpal temperature (PT) and induce pulpal damage due to heat generated by the curing unit and the exothermic reaction of the luting agent (LA). The aim was to measure the PT rise during ceramic inlay cementation by testing different combinations of dentin and ceramic thicknesses and LAs. The PT changes were detected using a thermocouple sensor positioned in the pulp chamber of a mandibular molar. Gradual occlusal reduction obtained dentin thicknesses of 2.5, 2.0, 1.5, and 1.0 mm. Light-cured (LC) and dual-cured (DC) adhesive cements and preheated restorative resin-based composite (RBC) were applied to luting of 2.0, 2.5, 3.0, and 3.5 mm lithium disilicate ceramic blocks. Differential scanning calorimetry was used to compare the thermal conductivity of dentin and ceramic slices. Although ceramic reduced heat delivered by the curing unit, the exothermic reaction of the LAs significantly increased it in each investigated combination (5.4-7.9 °C). Temperature changes were predominantly influenced by dentin thickness followed by LA and ceramic thickness. Thermal conductivity of dentin was 24% lower than that of ceramic, and its thermal capacity was 86% higher. Regardless of the ceramic thickness, adhesive inlay cementation can significantly increase the PT, especially when the remaining dentin thickness is <2 mm.