Diametral Tensile Strength Test Research Articles

Assessment of the Effects of Boron Nitride Nanoplatelets Reinforcement on the Physical and Mechanical Properties of the Geopolymer Prepared by Natural Kaolinite: An In Vitro Study

Introduction: We aimed to assess the effects of the addition of boron nitride nanoplatelets on the physical and mechanical properties of the geopolymer prepared by natural kaolinite. Methods: The compressive strength and diametral tensile strength tests were conducted according to BS 1881-116:1983 and ASTM E9-89a(2000) using an atomic force max instrument. The surface microhardness of the geopolymer was evaluated using a Digital Vickers microhardness tester, following the guidelines outlined in ASTM E92-82(2003). The contact angle (wettability) tests were carried out according to ASTM D7334-08(2022). Results: There were statistically significant differences among all study groups regarding compressive strength, diametral tensile strength, surface hardness, and wettability (p < 0.001). Conclusion: The boron nitride nanoplatelets reinforcement has a significant impact on the compressive strength, diametral tensile strength, surface microhardness, and wettability of the geopolymer, providing valuable insights for future research and development in this field.

Cytotoxicity and mechanical properties of biphasic calcium phosphate scaffold from Tegilarca granosa due to its composition

Background: Biphasic calcium phosphate (BCP) is graft material contained HA and TCP. Tegilarca granosa shell is a natural source that may converted into BCP. This study aims to determine the composition and cytotoxicity of BCP synthesized from Tegilarca granosa shell used various hydrothermal hours and to evaluate the mechanical properties of BCP scaffold. Methods: Tegilarca granosa shell was converted into BCP using hydrothermal method at 200˚C for 6h (Group 1); 9h (Group 2); and 12h (Group 3). The composition was determined by XRD and the cell viability were evaluated using MTT Assays. Each group was added with 20% gelatin ratio 50:50 (w/v) and freeze-dried to form scaffold. Scaffolds (Ø6mm x 4mm) were prepared for diametral tensile strength (DTS) test (n=6) and scaffolds (Ø7mm x 11mm) were used for compressive strength (CS) test (n=6). All data were analyzed using Kruskall-Wallis followed by Mann-Whitney test. Results: The composition of BCP (HA/ TCP) at Group 1, Group 2, and Group 3 were 81.80%/14,10%; 87%/6%; and 72%/21%. The cell viabilities were good for all groups. The DTS and CS test showed there was a significant difference between Group 1 and Group 3 scaffold, meanwhile there was no significant differences between Group 2 and Group 3 scaffold. Group 3 scaffold showed the highest DTS and CS, 6.921 MPa and 1,233 MPa. Conclusion: The BCP composition were depent on hydrothermal hours. Although all scaffold groups were non-toxic, but BCP scaffold synthesized from Tegilarca granosa shell using hydrothermal for 12 hours showed the highest mechanical properties.

Mechanical properties of simulated dentin caries treated with metal cations and L-ascorbic acid 2-phosphate.

This pH cycling study aimed to investigate the effects of L-Ascorbic acid 2-phosphate (AA2P) salts of Mg, Zn, Mn, Sr, and Ba on the surface microhardness, compressive strength, diametral tensile strength (DTS), and solubility of root canal dentin. 186 cylindrical dentin specimens from 93 teeth were fortified with optimal concentrations of AA2P salts of Mg (0.18mM), Zn (5.3µM), Mn (2.2 × 10-8M), Sr (1.8µM), and Ba (1.9µM). Saline was used as the control group. These dentin specimens underwent a 3-day cycling process simulating dentin caries formation through repeated sequences of demineralization and remineralization. Surface microhardness at 100 and 500µm depths (n = 10/subgroup), scanning electron microscopy (n = 3/group), compressive strength (n = 10/group), DTS (n = 6/group), and solubility (n = 5/group) tests were performed to analyze the dentin specimens. Data were analyzed using Kolmogorov-Smirnov, one-way ANOVA, and Post Hoc Tukey tests (p < 0.05). The control group had significantly lower microhardness at both depths (p < 0.001), reduced DTS (p = 0.001), decreased compressive strength (p < 0.001), and higher weight loss (p < 0.001) than all other groups. The Sr group had the highest compressive strength and microhardness among all the groups. The microhardness was significantly higher for the 500µm depth than the 100µm depth (p < 0.001), but the difference in microhardness between depths across groups was not significant (p = 0.211). All fortifying solutions provided some protection against artificial caries lesions. Therefore, these elements might have penetrated and reinforced the demineralized dentin against acid dissolution.

Preparation of an experimental dental composite with different Bis-GMA/UDMA proportions

ABSTRACT Three types of matrix with constant amount of TEGDMA (30 wt.%), and Bis-EMA (10 wt.%) and variable values of Bis-GMA (10, 5, or 0 wt.%) and UDMA (50, 55, or 60 wt.%) were prepared. Composites were filled with 45 wt.% of silanized silica. Both matrices and composites were tested for flexural strength (FS), diametral tensile strength (DTS), hardness (HV) and polymerization shrinkage stress. There were no significant differences for the DTS test. All materials meet the FS requirements for type 2 dental composites. A significant decrease in HV was observed for matrix non-containing Bis-GMA. The highest value of shrinkage stress had material without Bis-GMA and it amounted 16,6 ± 1.0 MPa (filled) or 13.6 ± 0.8 MPa (unfilled). It was also shown that increasing the amount of UDMA while simultaneously reducing Bis-GMA in the studied materials increases polymerization shrinkage stress, which could be unfavorable for dental materials.

Physicochemical Characterization of Novel Biomaterial Consisting of Biphasic Calcium Phosphate, Chitosan, Casein and Ethanolic Leaves Extract of Ormocarpum Cochinchinense.

Bioceramics are widely used as a biomaterial to promote bone regeneration. Bone defect management requires the placement of bone grafts. Though there are many bone grafts available, these have certain limitations like limited supply and second surgical site morbidity. Phytochemicals in plants are known to have bone regeneration capacity and are used in traditional medicine for bone fracture healing. The purpose of the study was to create a novel biomaterial consisting of a composite of biphasic calcium phosphate (BCP), chitosan (CH), casein (CA), and ethanolic leaves extract of Ormocarpum Cochinchinense (OC) fabricated and characterized for physicochemical properties. BCP-CH-CA-OC material was prepared and immersed in Simulated body fluid (SBF) for 21 days. Physical properties were analysed through X-Ray diffraction (XRD), Fourier Transform Spectroscopy (FTIR), and Scanning Electron Microscopy with Energy dispersion spectroscopy (SEM/EDS). Mechanical properties were analysed by compressive strength and diametral tensile strength tests. Using BET (Brunauer-Emmett-Teller) analysis and Nano computed tomography (CT) scan, porosity measurements were made. XRD did not show any significant change after immersion in SBF, indicating that the material was not under change and is stable. FTIR showed an increase in chitosan content, due to the loss of casein. SEM analysis showed the deposition of crystals and porous structure. EDS showed the deposition of minerals. Nano CT and BET analysis showed clinically significant porosity of 30%. The mechanical and physical properties of this novel biomaterial could be used in tissue engineering for the repair of bone defects in non-load-bearing areas. The physicochemical properties are at par with other materials used for the purpose of bone grafting. The novel biomaterial has the potential to be used in bone regenerative medicine in non-load-bearing applications.

Comparative Evaluation of Compressive and Diametral Tensile Strength in Die Stone Reinforced With Different Types of Nanoparticles: An In Vitro Study.

To investigate the effect of different types of nanoparticles on the compressive strength (CS) and diametral tensile strength (DTS) of type IV dental stones. A total of 100 specimens were made from the mould for all five groups. Four commercially available nanoparticles (aluminium oxide (Al2O3), silicon dioxide (SiO2), zinc oxide (ZnO), and zirconium oxide (ZrO2)) were used in this study in a concentration of 10%. CS and DTS tests were performed in a universal test machine. The data were statistically analysed using ANOVA and Student's t-test. The interaction between nanoparticles and the type of dental stone was found to be statistically significant (p < 0.05). CS and DTS values decreased by adding all four nanoparticles. The lowest CS and DTS were observed in 10% ZnO nanoparticles when added to type IV dental stone. It was concluded that the addition of nanoparticles (Al2O3, SiO2, ZnO, and ZrO2) to die stonesignificantly decreased the CS and DTS for all groups. Among all groups, the incorporation of 10% ZrO2 nanoparticles (group E) to die stone showed significantly less decrease in CSandDTS compared to Al2O3, SiO2, and ZnO. Incorporation of ZnO nanoparticles, on the other hand, showed a significantly more amount of decrease in theCSandDTScompared to Al2O3, SiO2, and ZrO2.

Physical Properties and Antimicrobial Release Ability of Gentamicin-Loaded Apatite Cement/α-TCP Composites: An In Vitro Study.

Apatite cement (AC), which has excellent osteoconductive ability, and alpha-tricalcium phosphate (α-TCP), which can be used for bone replacement, are useful bone substitute materials. The objective of this study was to clarify the physical properties and antimicrobial release ability of antibiotic-loaded AC/α-TCP composites in vitro. Gentamicin-loaded, rapid setting AC/α-TCP composites were prepared in 2 mixing ratios (10:3 and 10:6). The cement paste of AC/α-TCP composites was prepared in a plastic mold and dried in a thermostatic chamber at 37 °C and 100% relative humidity for 24 h. A diametral tensile strength test, powder X-ray diffraction analysis, and gentamicin release test were performed. The diametral tensile strengths of the AC/α-TCP composites were significantly less than that of AC alone. Powder X-ray diffraction patterns exhibited the characteristic peaks of hydroxyapatite in the AC/α-TCP composites and gentamicin-loaded AC/α-TCP composites. The concentration of the released gentamicin was maintained above the minimum inhibitory concentration of Staphylococcus aureus until Day 30 in both the gentamicin-loaded AC/α-TCP composites (10:3 and 10:6). Our results suggest that a gentamicin-loaded AC/α-TCP composite has potential as a drug delivery system. Further study is essential to investigate the antimicrobial activity and safety of the gentamicin-loaded AC/α-TCP composites in animal models.

Mechanical Properties of Giomer After Immersion in Carbonated Drinks

&#x0D; Introduction: Giomer is a resin-based restorative material consisting of prereacted glass ionomer (PRG) filler which can release fluoride. Carbonated beverages, popular beverages which contain acids that rich in H+ ions, can diffuse into the resin-based restoration and cause high solubility. Objective: To analyze the effect of immersion in carbonated drinks on water absorption and diametral tensile strength of giomer. Methods: Giomer was packed into a stainless-steel mold to obtain sample with diameter of 6.0±0.03mm and height of 3.0±0.09mm. The samples were divided into 2 groups for water absorption test and 3 groups for diametrical tensile strength test. Ten samples of giomer were soaked in artificial saliva for 4 days as a control group, 10 giomer samples were immersed in carbonated drinks for 6 hours, then replaced with artificial saliva for 18 hours and repeated for 4 days as a treatment group, and 10 samples of giomer were used as immediate group for direct diametral tensile strength test. Samples were incubated at 37°C. Results: Mann-Whitney test showed no significant difference (p&gt;0.05) in giomer absorption between the control group (0.99±0.54%) and the treatment group (2.37±2.62%). One Way ANOVA test showed significant difference (p&lt;0.05) in giomer diametral tensile strength among the immediate group (29.6±3.7MPa), the control group (51.1±3.9MPa) and the treatment group (44.8±5.3MPa). Conclusion: Immersion in carbonated beverages did not show significant difference with artificial saliva for the water absorption ability of giomer. However, the diametral tensile strength of giomer decreased after immersion in carbonated beverages for 24 hours.

The Effect of ZnO on the Physicochemical and Mechanical Properties of Aluminosilicate Dental Cements

In this study, the effect of the addition of various amounts of ZnO (0, 1, 2, and 3 wt. %) to aluminosilicate bioactive glass (BGs) network (SiO2-Al2O3- P2O5-CaF2-CaO-K2O-Na2O) on the mechanical properties of the fabricated glass ionomer cement (GIC) samples was studied. The GIC samples were fabricated by mixing the synthesized aluminosilicate BGs with Rivaself cure liquid. The synthesized aluminosilicate glass was characterized using differential thermal analysis (DTA), X-Ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Besides, the mechanical properties of GICs were evaluated using Vickers microhardness and Diametral tensile strength (DTS) test. According to DTA analysis, the glass transition temperature (Tg) of aluminosilicate BGs was decreased from 575 to 525 °C. According to the results, the aluminosilicate BGs with an amorphous state (~90%) and the grain size of 36 μm were synthesized. Doping of the ZnO to glass network up to 3 wt. % could increase the amorphous phase up to 95% and decrease the grain size of the particles up to 28 μm. The microhardness and DTS of the GIC samples containing the aluminosilicate BGs were about 677 Hv and 8.5 MPa, respectively. Doping of ZnO to the glass network increased the mentioned values up to 816 Hv and 12.1 MPa, respectively.

Evaluation of diametral tensile and compressive strengths of different types of nanocomposites for dental applications

This study aims to evaluate the diametral tensile strength (DTS) and compressive strength (CS) of restorative composite resins that applied as restorative materials in the field of dentistry. The composites were prepared from different sets of monomers which divided into six groups (A, B, C, D, E, and F) according to the type and ratios of monomers used in preparing the matrix materials, excepted the basic monomer (2, 2 propyl bisphenol glycidyl dimethacrylate (Bis-GMA)) that added at constant ratio (40 wt%), in addition tothe nano-inorganic fillers [SiO2, ZrO2, HA, and Al2O3] which adding individually. Ninety specimens were prepared for diametral tensile strength test, which divided into six groups according to the prepared resin matrix and five sub-divided groups according to types of fillers of prepared composites, and for compressive strength test, the same numbers of specimens were prepared. In the beginning, the diametral tensile strength (DTS) and compressive strength of the prepared matrices were determined and then study the effect of adding the nano-inorganic fillers on the results of these properties for the prepared dental restorations nanocomposites materials. The results show that the composites based on resin matrix of group (D) having the selected monomers (BIS-GMA, meth acrylamide, methacrylic acid, and 1–6 hexanediol methacrylate) that reinforced with silica nanoparticle have higher properties as compared with other types of the prepared nanocomposite, where these values reached to (54 MPa and 174 MPa) for diametral tensile strength and compressive strength, respectively.

The pH and Bismuth Oxide Particle Size can Affect Diametral Tensile Strength of Mineral Trioxide Aggregate.

Objective:The aim of the present study was to evaluate the effect of different pHs (4.4, 5.4, 6.4, 7.4, 8.4, and 9.4) and three different particle sizes of bismuth oxide on diametral tensile strength (DTS) of white Mineral Trioxide Aggregate (WMTA).Methods:Thirty cylindrical moulds were divided into six groups of five; WMTA was mixed, placed inside the moulds, and wrapped in pieces of gauze soaked in synthetic tissue fluid (STF) with pH values of either 4.4, 5.4, 6.4, 7.4, 8.4, 9.4. For bismuth oxide, eighteen similar molds were divided into three groups of six (n=6). Then bismuth oxide with three particle sizes, including fine (120 nm), medium (200 nm), and coarse (10 μm), were provided and added to the Portland cement, which did not have any bismuth oxide to create WMTA. Then WMTA was mixed, placed inside cylindrical molds. After incubation at 95% humidity for 48 hours, samples were subjected to DTS testing by an Instron Universal testing machine with a crosshead speed of 1 mm/min. Then, one sample from each group was subjected to scanning electron microscope (SEM) analysis. Data were analysed by ANOVA and Tukey tests (α=0.05).Results:The comparison of DTS in pH groups were: 8.4>7.4>9.4>6.4>5.4>4.4 (P<0.05); and in bismuth oxide groups were: fine particles > medium particles > coarse particles (P<0.05). Acidic pH, negatively affected the distribution of Ca2+ and Si4+ ions, while bismuth oxide with fine particles enhanced it.Conclusion:Acidic pH can decline the DTS of MTA significantly. However, reducing the particle size of bismuth oxide can increase the DTS of MTA significantly.

Effect of Incorporating Strontium Fluoride and Fluoride on Compressive and Diametral Tensile Strengths of Biodentine

Abstract: Objective: The objective of this study was aimed to evaluate the effect of incorporation strontium fluoride and fluoride on compressive and diametral tensile strengths of biodentine. Materials and Methods: Materials used in this study was divided into three main groups according to materials used Group I: Calcium silicate based material (biodentine) as a control material, Group II: Strontium fluoride modified calcium silicate based material, Group III: Fluoride modified calcium silicate based material. Each main group was subdivided into two subgroups according to test type (compressive and diametral tensile strength). Each subgroups dividing into two categories according to storage time at one week and one month. Results: According to compressive and diametral tensile strength test, biodentine recorded highest compressive and diametral tensile strength followed by strontium fluoride modified biodentine followed by fluoride modified biodentine. For storage time the four weeks compressive and diametral tensile strength is higher than Seven days. Conclusion: Modification of biodentine with strontium fluoride and fluoride don’t have considerable effect on the tested properties of biodentine. Key Words: Biodentine, compressive strength, strontium fluoride, fluoride.

Evaluation of physical-mechanical properties of self-adhesive versus conventional resin cements

Aim: The purpose of this study was to compare the microhardness, diametral tensile strength, compressive strength and the rheological properties of self-adhesive versus conventional resin cements. Methods: Specimens of a conventional (RelyX ARC) and 3 self-adhesive (RelyX U200, Maxcem Elite, Bifix SE) types of resin cements were prepared. The Knoop test was used to assess the microhardness, using a Microhardness Tester FM 700. For the diametral tensile strength test, a tensile strength was applied at a speed of 0.6 mm/minute. A universal testing machine was used for the analysis of compressive strength and a thermo-controlled oscillating rheometer was used for the Rheology test. One-way ANOVA and Tukey’s test (α=0.05) were used for data analysis. Results: According to microhardness analysis, all the cements were statistically similar (p&gt;0.05), except for Maxcem that presented lower hardness compared with the other cements in relation to the top surface (p&lt;0.05). In the diametral tensile strength test, Relyx U200 and RelyX ARC cements were statistically similar (p&gt;0.05), presented higher value when compared to the Maxcem and Bifix cements (p&lt;0.05). The compressive strength of RelyX ARC and Maxcem Elite cements was statistically higher than RelyX U200 and Bifix cements (p&lt;0.05). Regarding the rheology test, Maxcem Elite and RelyX ARC cements showed a high modulus of elasticity. Conclusions: The self-adhesive cements presented poorer mechanical properties than conventional resin cement. Chemical structure and types of monomers employed interfere directly in the mechanical properties of resin cements.

Mechanical Test of Aluminum-Zirconium-Silicate Composite Prototype with Filler Volume Variation

Recently, ceramic material has become a main object of scientific interest especially in dental material. The advance of dental materials technology has led to use of zirconia-based ceramics for composite filler. In this study, composite filler has been synthesized from natural zircon sand through geopolymerization method. Composite prototype were made with different filler volume to evaluate mechanical properties including hardness number and diametral tensile strength. Samples divided into two groups with 50 wt% filler volume (group A) and 75 wt% filler volume (group B) which 3 samples for each group. The surface micro hardness of each group tested by Leco M-400-H1 vickers microhardness testing machine and for diametral tensile strength tested using universal testing machine (Lloyd) with crosshead speed of 1,0 ± 0,25 mm/min. The data were analyzed using independent sample t-test. The results showed that the average of hardness number on group A was 13,8 VHN while for group B was 24,1 VHN. The average of diametral tensile strength for group A was 20,461 MPa and 27,689 MPa for group B. Statistical result showed that the value (P&lt;0,05). The conclusion, there is a signifficant difference on the result of hardness test between group A (50 wt% filler volume) and group B (75 wt% filler volume) and also on diametral tensile strength test.

Diametral Tensile Strength and Hardness Evaluation of Prototype Composite Based on Natural Zircon Sand Using Geopolymerization Method with Coupling Agent Variation

The widely use of dental composite triggers a lot of research to synthesize composite made from natural sources. One of the natural sources that could be used as a filler of composite is natural zircon sand from Indonesia. The physical properties of dental composite, such as Diametral Tensile Strength (DTS) and hardness could be affected by the filler of the composite. The aim of this research is to determine the value of diametral tensile strength and hardness of prototype composite with natural zircon sand-based filler by using geopolymerization method with various coupling agents. The procedures began from synthesizing Zirconia-Alumina-Silica filler from natural zircon sand using geopolymerization method with two different coupling agents, 3-mercapto propyltrimethoxysilane (3-MPTS) and 3-aminopropyltriethoxysilane (3-APTS), which then mixed with resin matrix to form composite resin, some of the samples were then subjected to a DTS test using Lloyd Universal Testing Machine (5.6 N initial load) until a crack/fracture was formed while some of them was subjected to a hardness test using Vickers Hardness Tester. The results showed the average DTS of dental composite using MPTS coupling agent was 13.78 MPa, while the average DTS of dental composite using APTS coupling agent was 8.90 MPa, and the average hardness result of dental composite coated by 3-MPTS was higher (20.68 VHN) than composite coated by 3-APTS (18.02 VHN). This difference could be affected by filler particle composition, filler surface area and also coupling agent variation. In conclusion, the tensile strength of the prototype resin composite sample group with the natural zircon sand filler using MPTS coupling agent was higher than the APTS coupling agent group.

Effects of the reinforced cellulose nanocrystals on glass-ionomer cements

ObjectiveGlass-ionomer cements (GICs) modified with cellulose nanocrystals (CNs) were characterized and evaluated for compressive strength (CS), diametral tensile strength (DTS) and fluoride release (F−). MethodsCommercially available GICs (Maxxion, Vidrion R, Vitro Molar, Ketac Molar Easy Mix and Fuji Gold Label 9) were reinforced with CNs (0.2% by weight). The microstructure of CNs and of CN-modified GICs were evaluated by transmission electron microscopy (TEM) and by scanning electron microscopy (SEM) while chemical characterization was by Fourier transform infrared spectroscopy (FTIR). Ten specimens each of the unmodified (control) and CN-modified materials (test materials) were prepared for CS and DTS testing. For the fluoride release evaluation, separate specimens (n=10) of each test and control material were made. The results obtained were submitted to the t-test (p<0.05). ResultsThe CN reinforcement significantly improved the mechanical properties and significantly increased the F− release of all GICs (p<0.05). The GICs with CNs showed a fibrillar aggregate of nanoparticles interspersed in the matrix. The compounds with CNs showed a higher amount of C compared to the controls due to the organic nature of the CNs. It was not possible to identify by FTIR any chemical bond difference in the compounds formed when nanofibers were inserted in the GICs. SignificanceModification of GICs with CNs appears to produce promising restorative materials.

Influence of activation mode, fatigue, and ceramic interposition on resin cements’ diametral tensile strength

This study evaluated the influence of activation modes, on Diametral Tensile Strength (DTS) of dual cured resin cements subjected to a Mechanical Fatigue test (MF). Four dual-cured resin cements (RelyX UNICEM [U], RelyX ARC [A], ENFORCE [E] and Nexus 2 [N]) were activated by three different curing modes as follows: Self-Curing (SC), Dual Cure activation with photoactivation executed directly (DC) and Dual Cure activation with Photoactivation Through Porcelain (DCTP). After 24 hours, half of the sample was subjected to 30.000 fatigue cycles at 1 Hz frequency and 12 N load. Then, all specimens were subjected to DTS test in Instron Universal Testing Machine and data were analyzed by three-way ANOVA and Tukey's Test (5%). The results of DTS test means (MPa) and standard deviation, for each cement factor activated by SC, DC and DCTP was respectively: U (28.12 ± 5.29; 37.44 ± 6.49 and 40.10 ± 4.39), A (49.68 ± 8.42; 55.12 ± 5.16 and 63.43 ± 6.92), E (49.12 ± 3.89; 56.42 ± 8.88 and 56.96 ± 6.45) and N (61.89 ± 11.21; 59.26 ± 9.47 and 62.56 ± 10.93). Turkey's test indicated that DC is related to the highest DTS values; Nexus 2 DTS remained the same independently of activation mode and that the Porcelain disk interposition enhanced DTS only for RelyX ARC the ANOVA statistical test indicated that MF didn't alter the DTS values for all experimental groups. MF results clinical implication is that all cements tested exhibited, in an immediate loading, good cross linked bonds quality.

Effect of phytic acid on the setting times and tensile strengths of calcium silicate-based cements.

This study aimed to evaluate and compare the effect of 1% phytic acid as a mixing medium on the setting times and diametral tensile strengths of different calcium silicate-based cements. Specimens for four experimental groups (n=20/each) were fabricated by mixing ProRoot MTA® (Dentsply) and Biodentine® (Septodont) powders with their original liquids or with 1% phytic acid. Half of the samples in each group were immediately subjected to setting time tests, whereas the remaining half was subjected to the diametral tensile strength test after 3weeks. When mixed with their original liquids, the setting time of MTA was significantly longer than that of Biodentine® (P<0.05). When mixed with phytic acid, the initial and final setting times of both test materials significantly decreased (P<0.05). The diametral tensile strength of Biodentine® was significantly greater than that of MTA (P<0.05). However, phytic acid had no effect on this outcome (P>0.05).

Development of a dual-cure mineral trioxide aggregate-based cement: Biological, physical, and mechanical properties.

Purpose:The purpose of this study is to compare the physical, mechanical, and biocompatibility properties of a new dual-cure white mineral trioxide aggregate (D-W-MTA) and a commercial W-MTA.Materials and Methods:Diametral tensile strength (DTS), water sorption (WSp), and water solubility (WSl) tests were performed. Cytotoxicity was observed in primary culture of human pulp fibroblasts (HPFs) and mouse 3T3/NIH fibroblast lineage. Specimens of both materials were embedded in 1 mL of Dulbecco's modified essential medium for 24 h. Cells were incubated for 24 h with the eluates. Cytotoxicity was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and genotoxicity by micronucleus (MN) formation. Data were analyzed by ANOVA and Kruskal–Wallis tests considering P < 0.05.Results:D-MTA and W-MTA not showed cytotoxic effect on the two cell lines. However, D-MTA stimulated HPF growth. The MN count was similar to that of the control group for D-MTA and W-MTA. D-MTA presented lower DTS and WSl. Nevertheless, WSp was similar in the two groups.Conclusion:The results suggest that D-MTA is a promising material for pulp capping. Thus, in vivo tests should be performed to evaluate the performance of this material.

Effect of storage time and chlorhexidine addition on the mechanical properties of glass ionomer cements

Abstract: Aims: To evaluate the effect of the chlorhexidine (CHX) incorporation and the storage time on the mechanical properties of glass ionomer cements (GICs). Methods: The following GICs were evaluated: Ketac Molar Easymix (KM), Vidrion R (VR) and Vitromolar (VM), containing or not CHX. GIC liquid was modified by adding 1.25 % CHX digluconate and then manipulated with the power and placed into the stainless steel cylindrical or bar-shaped molds. GICs specimens were stored into water for 1, 7 and 28 days. After these periods, specimens were submitted to flexural, diametral tensile and compressive strength tests, according to ISO standards. Data from mechanical tests were statistically analyzed using 2-way ANOVA and Tukey tests. Results: Overall, the storage time did not influence any of the mechanical properties of the GICs tested. In contrast, the inclusion of CHX reduced significantly these properties for all GICs tested. KM presented the highest values of compressive strength for all storage times. KM + 1.25% CHX had lower compressive strength results than KM, however, it showed similar results when compared to another GICs without CHX. Conclusions: The presence of chlorhexidine, independent of the storage time, interfered on the mechanical characteristics of GIC.