Instron Universal Testing Machine Research Articles

Incorporation of Arginine to Commercial Orthodontic Light-Cured Resin Cements-Physical, Adhesive, and Antibacterial Properties.

(1) Background: The amino acid arginine is now receiving great attention due to its potential anti-caries benefits. The purpose of this in vitro study was to evaluate the shear bond strength (SBS), ultimate tensile strength (UTS), and antimicrobial potential (CFU) of two arginine-containing orthodontic resin cements. (2) Methods: Forty bovine incisors were separated into four groups (n = 10): Orthocem, Orthocem + arginine (2.5 wt%), Transbond XT, and Transbond XT + arginine (2.5 wt%). The brackets were fixed to the flat surface of the enamel, and after 24 h the SBS was evaluated using the universal testing machine (Instron). For the UTS test, hourglass samples (n = 10) were made and tested in a mini-testing machine (OM-100, Odeme). For the antibacterial test (colony forming unit-CFU), six cement discs from each group were made and exposed to Streptococcus mutans UA159 biofilm for 7 days. The microbiological experiment was performed by serial and triplicate dilutions. The data from each test were statistically analyzed using a two-way ANOVA, followed by Tukey’s test (α = 0.05). (3) Results: The enamel SBS mean values of Transbond XT were statistically higher than those of Orthocem, both with and without arginine (p = 0.02033). There was no significant difference in the SBS mean values between the orthodontic resin cements, either with or without arginine (p = 0.29869). The UTS of the Transbond XT was statistically higher than the Orthocem, but the addition of arginine at 2.5 wt% did not influence the UTS for either resin cement. The Orthocem + arginine orthodontic resin cement was able to significantly reduce S. mutans growth, but no difference was observed for the Transbond XT (p = 0.03439). (4) Conclusion: The incorporation of arginine to commercial orthodontic resin cements may be an efficient preventive strategy to reduce bacterial growth without compromising their adhesive and mechanical properties.

Degree of conversion and cohesive strength of conventional dual resin and self-adhesive cements by using of different forms of activation

The aim of this study was to evaluate the degree of conversion (DC) and cohesive strength (CS) of two conventional resin cements and a self-adhesive resin cement using different forms of activation. Two conventional dual resin cements (Variolink II and RelyX ARC) and a self-adhesive resin cement were polymerized in three different ways of activation, namely Chemically Activated (CA), Light Activated with Interposition of a resin disc (LI) and Light-Activated (L). The DC was evaluated using Fourier Transformed Infrared Spectroscopy - FTIR (Spectrum 100). In the CS test, the samples were tested until fracture in a universal testing machine (Instron 4411). The mean values obtained in the DC and CS tests were evaluated using two-way analysis of variance (ANOVA) (cement and activation) and Tukey test (p≤0.05). Irrespective of the activation mode, RelyX ARC showed the highest DC values, RelyX U200, the lowest values, and Variolink II intermediate values. Group L always had higher for DC and CS values than group CA. Among the resin cements, irrespective of the activation mode, there were no differences in CS values. The chemical activation mode of dual resin cements led to lower DC and CS values. RelyX ARC cement had the highest DC values and RelyX U200 cement the lowest values, however, in relation to CS, there were no differences.

Comparison Study on Fiber and Cocopeat from Young Coconut Husks and Old Coconut Husks

Fiber and cocopeat are waste products from coconut husks that can be turned into value added products. Fiber and cocopeat from old coconut husks are well known in coconut industry in the world. This paper described fibre strength from young coconut husks, nutrient content and water-holding ability of young coconut cocopeat compared to old coconut cocopeat. The strength of fiber was determined by using Instron Universal Testing Machine. The results showed that mean load at break for young coconut fiber was 13.76 N while mean load at break for old coconut fiber was 14.93 N. Maximum tensile stress for young coconut fiber was 1.55 MPa and 1.76 MPa for old coconut fiber. The nutrient contents were determined for young cocopeat and old cocopeat resulted as phosphorus (372.79 ppm, 339 ppm), potassium (6829.68 ppm, 10040.46 ppm), calcium (508.74 ppm, 578.40 ppm), magnesium (468.67 ppm, 715.60 ppm) and sodium (1579.70 ppm, 3917.60 ppm). The pH value was 6.55 and 5.39 respectively. The ash contents were 2.62% for young cocopeat while 4.06% for old cocopeat. For water holding ability test, moisture content of each sample from young coconut cocopeat and old coconut cocopeat was determined by using soil moisture meter. After seven days with water added 500 ml two times/day, results showed that water holding ability for peat moss was the best while young cocopeat was better than the old cocopeat. All the results showed that fiber and cocopeat from young coconut husk have high potential for sustainable production in the coconut industry.

Comparative evaluation of the fracture resistance of endodontically treated teeth with different access designs

Background: Most important step for successful endodontic treatment is access cavity preparation. However, the removal of tooth structure needed for access cavity leads to compromise of pericervical dentin and remaining dentin thickness undermining the strength of tooth and increasing the root fracture propensity under functional loads. Therefore, in the present study fracture resistance of endodontically treated teeth with Traditional endodontic cavity [TEC] to Conservative endodontic cavity [CEC] and pericervical bonding of composite resin in different root filled teeth was evaluated by using Universal Testing Machine. Materials and Methods: Freshly extracted single rooted premolars were selected and randomly divided into two groups: Group 1: Traditional Endodontic Cavity (TEC) (n=24) Group 2: Conservative endodontic cavity (CEC) (n=24) 1. GROUP 1a: TEC restored with Cavit 2. GROUP 1b: TEC restored with nanocomposite 3. GROUP 2a: CEC restored with Cavit 4. GROUP 2b: CEC restored with nanocomposite 5. The specimens were then loaded to fracture in Instron Universal Testing machine and the fracture resistance data was further analysed and compared. Results: The mean fracture strength for CEC restored with nanocomposite was significantly higher than all the other groups. (p

Incorporation of Hydroxyapatite and Calcium Triphosphate in the Epoxy Resin-Based Sealer

Abstract Objective This study aims to assess and compare the influence of hydroxyapatite (HA) and tricalcium phosphate (TCP) nanoparticles on a commercially available epoxy resinbased sealer, focusing on porosity and push-out bond strength. Materials and Methods This work was classified into a control group and two experimental groups. In each experimental group, the sealer was mixed with 2.5 wt.% of HA and TCP nanoparticles. Thirty extracted single-rooted teeth were utilized. After sectioning the crowns, the remaining roots of 15 teeth were used, up to 40 to 0.06, using a K3 rotary system. Smear layers were removed with 3 mL of 17% EDTA applied for 60 seconds. Then, the canals were irrigated with 3 mL of 2.25% NaOCl and 5 mL of distilled water. The strength of push-out bonds was tested via an Instron universal testing machine on a 2 mm section acquired from obturated canals. Data were assessed using one-way ANOVA and post hoc tests at a significance level of p < 0.05. Results A nonsignificant difference (p > 0.05) was evident when the three groups were crosschecked in terms of void volume and bond strength. Micro-CT evaluations revealed the lowest volume of voids to be 0.1152 mm3 (2.69%) for the HA group compared with the control group 0.1818 mm3 (3.9%) and the TCP group 0.2194 mm3 (4.33%). Mean bond strength values were 4.18 ± 1.77 MPa for group 1 (control), 4.19 ± 1.54 MPa for group 2 (HA 2.5%) and 3.76 ± 1.95 MPa for group 3 (TCP 2.5%). Groups 1 and 3 showed both cohesive and a mixed type of failure, while group 2 showed adhesive and a mixed type of bond failure. Conclusion Within the limitations of the study, incorporation of 2.5 wt% HA and TCP nanoparticles into AH Plus did not significantly affect the percentage volume of voids and the bond strength negatively.

Influence of manufacturing process technology on buckling behaviour of thinwalled, GFRP columns with a square cross-section

In this study, static compression of thin-walled, composite columns with square cross-section is presented. The influence of heat transfer during the manufacturing process of thin-walled column on the behaviour during compressive load has been investigated. Two series of the columns made of GFRP laminate with symmetric layup [45/-45/45/-45]s were manufactured using the autoclaving technique. To check the way of heat transfer during the curing process the two different methods of retaining and giving off heat from the produced element during its cooling in the autoclave process by using other process durations and mandrels were used. It is a well-known fact that different curing speeds and cooling rates affect the distribution of residual stresses inside the structure that could have a significant impact on its future structural performance. In case of this study, the target of these operations was to verify how the manufacturing process and generated in this process residual stresses are affecting buckling and postbuckling behaviour of the structures. Therefore, manufactured in this manner two series of four specimens were experimentally tested. The static compression tests were performed on Instron universal testing machine employing additionally a contactless digital image correlation system GOM ARAMIS ®. Additionally, the numerical model has been developed and used to perform FEM analysis including cooling process (manufacturing procedure simulation) and compression test (operating load simulation). TheThe obtained load-deflection and load-shortening function enabled to determine critical loads and postcritical stiffness and verify how different distribution of residual stresses is affecting the stability of such columns.

One-Pot Synthesis of Supertough, Sustainable Polyester Thermoplastic Elastomers Using Block-Like, Gradient Copolymer as Soft Midblock

It remains challenging to synthesize supertough thermoplastic elastomers (TPEs) since the stretchability and tensile strength are mutually exclusive. Here, we report a one-pot strategy for the prep...

Assessment of Resorbable and Non-resorbable Fixation Systems in Sagittal Split Ramus Osteotomy: An In vitro Study.

The internal fixation has been purpose of study for many years, but there is still no consensus on the best method of fixation in relation to resistance for bilateral sagittal split ramus osteotomy (BSSO) using plates. Therefore, the aim of this study was to assess five different methods of osteosynthesis using resorbable and non-resorbable plates and screws in simulated sagittal split osteotomy (SSO) of the mandibular ramus. SSO was performed in 25 polyurethane synthetic mandibular replicas. The distal segments were moved forward 5mm, and the specimens were grouped according to the fixation method: Inion resorbable plate, KLS resorbable plate, standard four-hole titanium miniplate (Medartis), two standard four-hole titanium miniplates (Medartis) and an adjustable titanium miniplate (Slider/Medartis). Mechanical evaluation was performed by applying compression loads to first molar using an Instron universal testing machine up to a 5mm displacement of the segments. Resistance forces were obtained in Newtons (N), and statistical analysis was performed using the software R v. 3.5 with significance level of 0.05. Linear mixed models were used to compare the force required to move each type of plate. The results showed that the resistance of SSO was better accomplished using two titanium miniplates and KLS resorbable plate showed the least resistance. However, both titanium and resorbable plates behaved similarly in small displacements, which are most commonly observed in BSSO postoperative time. It can be concluded that both resorbable and non-resorbable systems might offer suitable mechanical resistance in the procedures where there are no mechanical postoperative complications.

Comparative evaluation of nano-filled and conventional adhesives for bonding of molar tubes.

It is of interest to compare the bonding characteristics of the two nano filled adhesives, Grandio (Voco, Cuxhaven, Germany) and Transbond Supreme LV (TSLV, 3M Unitek, Monrovia, California) with conventional bonding adhesive Transbond XT (TBXT, 3M Unitek) for bonding of molar tubes. 45 extracted human permanent molar teeth, divided into three groups of 15 each, were bonded with stainless steel molar tubes (3M Unitek, USA) using TBXT in Group 1, Grandio in Group 2, TSLV in Group 3. Remnant Index and shear bond strength was evaluated after 24 hrs. of storage with the aid of Instron Universal testing machine and Stereomicroscope respectively. Data were analysed using Analysis of Variance (ANOVA) test, Post-hoc Bonferroni test and Kruskal Wallis test. The mean SBS of Group 1(TBXT) was 13.86±3.27 MPa, Group 2 (Grandio) was 9.48±2.36 MPa and Group 3 (TSLV) was 11.64±2.71 MPa. Both nano-filled adhesives had SBS well above the clinically acceptable range. Assessment of ARI scores and type of bond failure revealed that adhesive failure for TBXT and TSLV and cohesive failure for Grandio. Nano-filled adhesives can be an appropriate substitute for the conventional adhesive for bonding of molar tubes.

Real-time in vitro measurement of denture-mucosa pressure distribution in a typical edentulous patient with and without implants: Development of a methodology

PurposeTo measure the pressure distribution on the oral mucosa in vitro by comparing the pressure distributions under a complete denture and that of an implant overdenture. Materials and methodAnatomically accurate models and conventional Class I complete denture (CD) were produced and subjected to cyclic loading using a 100 N vertical centric and unilateral masticatory load with the universal testing machine (Instron 3369). Four miniature pressure sensors were positioned at four different locations in the intaglio surface of the denture and recorded pressure at 100 Hz frequency measured during a 10-cycle load at 1 Hz. Testing was repeated in different clinical combinations; CD vs. single implant overdentures (1-IOD), CD vs. two, three and four implant overdentures (2-IOD, 3-IOD vs. 4-IOD). The pressure profile (kPa) of complete dentures were measured and compared to the implant overdenture combinations. Collected data was statically analysed using SPSS and one-way analysis of variance. ResultsThe highest mean pressure was observed in CD group, with the mean mandible buccal ridge pressure value of 212.82 kPa ± 136.9 due to its surface area. There were no statistically significant differences between the group combinations (p = 0.146) but between various locations in the mean pressure recorded across the five denture/overdenture combinations. ConclusionCD experienced large pressure values on mandibular denture. 1-IOD demonstrated the most pressure in comparison to CD where with an increase in the number of implants used, it transformed the denture from being pure-borne mucosa to an implant overdenture, providing support and distributing the pressure amongst the implants.

Evaluation of bond strength between nanohybrid composite teeth and two different denture base materials (comparison study )

Purpose: aim of the study was to compare the bond strength of nanohybrid composite artificial teeth (NHC) and two types of denture base material ( acrylic denture base material and thermoplastic monomer free semi-rigid micro crystalline polymer denture base material (Karadent) . Material and Methods : nanohybrid composite teeth (premolars) was sliced equally , grooved for increasing contact surface and attached to 16 discs of denture base material (8 for each group), then the discs where grouped into two groups . The samples were subjected to tensile forces till failure by using the Instron Universal testing machine. Results : bonded nanohybrid composite teeth (NHC) to conventional acrylic denture base disc specimens showed better results in comparison to thermoplastic monomer free semi-rigid micro crystalline polymer denture base materials ones. Conclusion : it is recommended to use NHC teeth more often with conventional acrylic denture bases than thermoplastic monomer free semi-rigid micro crystalline polymer denture base materials.

Evaluation of the reduction, tightening and gripping performance of an innovative set screw technology for instrumented posterior lumbar fusion: A biomechanical study

BackgroundInstrumented posterior lumbar fusion with top-loading pedicle screw systems (PSS) requires fully tightened set screws to achieve a secure fixation and symmetric load condition. This assumes a complete reduction of the rod by 90°, which is not always attainable in situ, especially under constraint. The objective of this work is to compare the mechanical performance of different innovative set screw technologies, which should improve the tightening process. HypothesisThe hypotheses of the study are that modifications to the screw and screwdriver unit can (1) improve the quality of set screw tightening and (2) increase the axial gripping capacity of the construct. Materials and methodsThe four set screw technologies under investigation include a standard set screw with a flat surface (F-S; control group), a set screw with a convex surface (C-S) and a shaft tip method screwdriver used in combination with both flat (F-STM) and convex set screws (C-STM). The quality of set screw tightening is categorized as follows: failed=the rod is not completely reduced; reduced=the rod is successfully reduced but the set screw is not correctly fixed; good=remaining cases. An axial gripping capacity test is performed by a universal testing machine (Instron®) with a force capacity of 5kN. ResultsRegarding the quality of set screw tightening, comparisons between F-S vs. F-STM, F-S vs. C-STM and between C-S vs. C-STM show statistically significant differences (p<0.001). The axial gripping capacity test shows mean gripping forces of 1223N (STD 331) in the F-STM group and of 1724N (STD 168) in the C-STM group with statistically significant differences between both groups (p=0.003). DiscussionSeveral biomechanical and clinical case studies have identified possible effects of misaligned rod-screw interfaces such as screw pull-out during rod reduction, screw loosening, screw or rod breakage, misalignment, adjacent segment degeneration and worsening of the clinical outcome. C-STM-technology thus supports controlled fixation in the sense of applying appropriate forces for correction or fixation during PSS assembly as well as friction-reduced final alignment and tightening with the aim to reduce implant loosening, hardware failure and reoperations, while respecting anatomical and biomechanical balance.

Arabinoxylan/graphene-oxide/nHAp-NPs/PVA bionano composite scaffolds for fractured bone healing.

The importance of bone scaffolds has increased many folds in the last few years; however, during bone implantation, bacterial infections compromise the implantation and tissue regeneration. This work is focused on this issue while not compromising on the properties of a scaffold for bone regeneration. Biocomposite scaffolds (BS) were fabricated via the freeze-drying technique. The samples were characterized for structural changes, surface morphology, porosity, and mechanical properties through spectroscopic (Fourier transform-infrared [FT-IR]), microscopic (scanning electron microscope [SEM]), X-ray (powder X-ray diffraction and energy-dispersive X-ray), and other analytical (Brunauer-Emmett-Teller, universal testing machine Instron) techniques. Antibacterial, cellular, and hemocompatibility assays were performed using standard protocols. FT-IR confirmed the interactions of all the components. SEM illustrated porous and interconnected porous morphology. The percentage porosity was in the range of 49.75%-67.28%, and the pore size was 215.65-470.87µm. The pore size was perfect for cellular penetration. Thus, cells showed significant proliferation onto these scaffolds. X-ray studies confirmed the presence of nanohydroxyapatite and graphene oxide (GO). The cell viability was 85%-98% (BS1-BS3), which shows no significant toxicity of the biocomposite. Furthermore, the biocomposites exhibited better antibacterial activity, no effect on the blood clotting (normal in vitro blood clotting), and less than 5% hemolysis. The ultimate compression strength for the biocomposites increased from 4.05 to 7.94 with an increase in the GO content. These exciting results revealed that this material has the potential for possible application in bone tissue engineering.

Laser retrieval of cemented zirconia single unit implant restoration: A pilot study: Part I - Force values.

To measure the retrieval force required to remove 1.5-mm-thick CAD/CAM zirconia copings cemented on zirconia (Zr) and titanium (Ti) stock implant abutments after a single application of erbium-doped yttrium scandium gallium garnet (Er:YSGG) laser. A total of 60 monolithic Zr copings were cemented on Zr and Ti implant abutments with either a resin-modified glass-ionomer (RelyX Luting Plus Cement, 3M ESPE; Rx) or a zinc oxide eugenol cement (Temp-Bond, Kerr; Tb). These abutment-coping specimens were randomly divided into 12 groups based on laser application (vs control [C]), abutment type (Zr vs Ti), cement (Rx vs Tb), and storage condition (dry [D] vs saline water [W]). Er:YSGG laser was applied at 6 W, 30% water-60% air, and 20 Hz (300 mJ/pulse energy) postcementation following a defined pattern. The force required to remove all the cemented copings from their abutments was measured on a universal testing machine (Instron model 4204). Descriptive statistics, multi-factor analysis of variance, and post hoc Tukey honest significant difference tests (α = .05) were performed. The mean peak force values at removal of the Zr abutment groups were 470.3 ± 151.33 N (ZrRxC), 161.7 ± 19.29 N (ZrRxD), 316.03 ± 95.24 N (ZrRxW), 103.27 ± 24.53 N (ZrTbC), 39.33 ± 6.21 N (ZrTbD), and 20.33 ± 6.45 N (ZrTbW); and for the Ti abutment groups were 349.80 ± 106.82 N (TiRxC), 84.63 ± 14.02 N (TiRxD), 177 ± 62.57 N (TiRxW), 54.77 ± 9.10 N (TiTbC), 22.67 ± 4.32 N (TiTbD), and 11.57 ± 2.30 N (TiTbW). Within the limitations of this study, it can be concluded that Er:YSGG laser allows for easier removal of cemented Zr copings with lower removal forces, with Ti abutment groups requiring lower forces than Zr abutment specimens. No significant difference was seen between laser and control groups for Tb compared to Rx. Er:YSGG laser shows great clinical promise for predictable retrievability of cemented, monolithic Zr implant crowns, especially with stronger resin-based cement such as Rx. With further clinical evidence, this could be very useful for clinicians managing cement-retained implant crown complications.

Effects of Veneering Ceramic and Methods on Failure Load of Veneered Zirconia

Background: A variety of veneering options to zirconia frameworks are now available. The purpose of this study is to evaluate the effect of veneer materials, veneering methods, cement materials, and aging on the failure load of bilayered veneer zirconia. Material and methods: Zirconia bars (20 × 4 × 1 mm) were veneered to 2 mm total thickness (n = 10/group). Veneering method groups included: 1. Hand-layered feldsparthic porcelain (VM = Vita VM9, Vident) and fluorapatite glass–ceramic (CR = IPS e.max Ceram, IvoclarVivadent); 2. Pressed feldspathic porcelain (PM = Vita PM9, Vident) and fluorapatite glass–ceramic (ZP = IPS e.max ZirPress, IvoclarVivadent); 3. CAD-/CAM-milled feldspathic ceramic (TF = Vitablocs Triluxe Forte, Vident) and lithium-disilicate glass–ceramic (CAD = IPS e.max CAD, IvoclarVivadent). CAD/CAM veneers were either cemented with resin cements (P = Panavia21, KurarayDental), (R = RelyX Ultimate, 3M ESPE), (M = Multilink Automix, Ivoclar Vivadent) or fused with fusion glass–ceramic (C = CrystalConnect, IvoclarVivadent). A three-point bending test (15 mm span, zirconia on tension side) was performed on Instron universal testing machine (ISO 6872) recording load-to-failure (LTF) of first veneer cracks or catastrophic failure. For group VM, PM, TF-M, TF-C, CAD-M, CAD-C, ten more bars were prepared and aged with cyclic loading (100,000 cycles, 50% LTF) and thermocycling (2000 cycles) before testing. Data were analyzed by ANOVA, Tukey HSD post hoc tests, and t-test (α = 0.05). Zirconia veneered with IPS e.max CAD by fusing had significantly higher failure load compared with zirconia veneered with other veneering materials (p ≤ 0.05). For cemented veneers, the cement type had a significant effect on the failure load of the veneer zirconia specimens. Specimens cemented with Panavia 21 had a lower resistance to loading than other cements. The aging experiment revealed a significant difference in failure load between non-aged and aged bars in groups VM and PM, but not in the groups with CAD-/CAM-milled veneers. In conclusion, veneer materials, veneering methods, and cement materials have a significant effect on the failure load of bilayered veneer zirconia. CAD-/CAM-milled veneer zirconia is not susceptible to aging performed in this study.

Ceramic Printing - Comparative Study of the Flexural Strength of 3D Printed and Milled Zirconia.

To determine and compare the mechanical properties of 3D-printed yttriastabilized zirconia to milled isostatic pressed yttria-stabilized zirconia, with the following hypotheses: (1) The flexural strength of 3D-printed yttria-stabilized zirconia is comparable to milled yttria-stabilized isostatic pressed zirconia; and (2) thermocycling and chewing simulation do not affect the flexural strength of 3D-printed yttria-stabilized zirconia. A total of 30 bars of an experimental 3D-printed 3 mol% yttriastabilized zirconia (LithaCon 3Y 230, Lithoz) and 10 bars of milled isostatic pressed zirconia (Prettau Zirconia, Zirkonzahn) were utilized. The printed zirconia bars were divided into three groups (n = 10 bars per group): (1) untreated (control); (2) thermocycled; and (3) tested after chewing simulation. A flexural strength test was performed on all samples using a three-point bend test in an Instron Universal testing machine. One-way analysis of variance on ranks was used to compare milled to printed zirconia. The effects of thermocycling and load cycling on 3D-printed zirconia were also determined. The flexural strength values for milled and printed zirconia were 936.3 ± 255.0 MPa and 855.4 ± 112.6 MPa, respectively. There was no statistically significant difference in flexural strength between the milled and printed zirconia (P = .178). No statistically significant differences were observed between the control 3D-printed zirconia group and the thermocycled (888.4 ± 59.3 MPa) or load-cycled printed zirconia (789.6 ± 133.8 MPa; P = .119). Printed 3 mol% yttria-stabilized zirconia has comparable flexural strength to milled yttria-stabilized isostatic pressed zirconia. The thermocycling and chewing simulation used in this study did not significantly alter the flexural strength of the printed 3 mol% yttria-stabilized zirconia. These results indicate a promising role for 3D printing in the fabrication of zirconia restorations. Additional studies are needed to explore the full potential of this technology.

Effect of surface treatment on mechanical, physical and morphological properties of oil palm/bagasse fiber reinforced phenolic hybrid composites for wall thermal insulation application

The effect of 2%v/v silane and 4%v/v hydrogen peroxide treatment on mechanical, physical and morphological characterization of oil palm empty fruit bunch (OPEFB) and sugarcane bagasse (SCB) fiber reinforced bio-phenolic hybrid composites has been evaluated in this work. The treated OPEFB and SCB fibers has been prepared with different ratio while maintaining 50%wt fiber loading, and then incorporated with the bio-phenolic resin by hand layup technique to produce pure and hybrid composites. Universal testing machine INSTRON has been used for tensile, flexural, and compressive strength analysis. Water absorption and thickness swelling are determined after 24 h. Fracture behaviour, void and fiber pull out of the specimen was observed by using scanning electron microscope in morphological analysis. The hybridization of silane treated 7OPEFB:3SCB fiber indicates better highest performance on tensile strength and modulus with 11.67 MPa and 1348.43 MPa. The silane treated 5OPEFB:5SCB hybrid composites show highest flexural and compressive strength, 16.82 MPa and 6.53 MPa, respectively. Obtained result showed silane treated 3OPEFB:7SCB hybrid composites displays lowest water absorption and thickness swelling after 24 h analysis and show less void content. This study indicated that 2%v/v silane coupling agent gives better enhancement of mechanical properties compared to 4%v/v hydrogen peroxide treatment. Silane treated 5OPEFB:5SCB fiber reinforced bio-phenolic hybrid composites fulfil requirement of the mechanical and physical properties needed for insulation board as per standard. It can be concluded from this study that silane treatment improve the performance of agriculture residue and the hybridization of bio-composites have potential to develop new class of eco-friendly thermal insulation and sustainable wall building materials.

The Effect of Incorporation of Cellulose Kenaf Fibers in Composite Resin on Mechanical Properties and Surface Topography Analysis Using Scanning Electron Microscopy

Abstract Objective This study aimed to evaluate the flexural and compressive strength of kenaf-reinforced composite resin as well as analyze the length and diameter of kenaf fibers and their surface topography. Materials and Methods Kenaf fibers were alkaline treated and wetted with coupling agent. Kenaf-reinforced composite resin was fabricated manually. Specimens for kenaf-reinforced composite resin (Tetric N Flow [Ivoclar Vivadent, Liechtenstein] + 2% kenaf) and control group (Tetric N Flow [Ivoclar Vivadent, Liechtenstein]) were prepared using stainless steel molds with dimension of 25 mm × 2 mm × 2 mm and 6 mm × 4 mm for flexural and compressive strength tests, respectively, and tested using Instron Universal Testing Machine (Shimadzu, Japan). Raw kenaf fibers, treated kenaf fibers, and fractured sample from flexural strength test were analyzed using scanning electron microscopy (SEM) (FEI Quanta FEG 450, United States). Data were analyzed using independent sample t-test. Significant level was set at p &lt; 0.05. Results Kenaf-reinforced composite resin has a lower flexural and compressive strength than the control group (p &lt; 0.05). SEM analysis revealed the average fibers’ length to be 1.24 mm and diameter ranging from 6.56 to 12.9 μm. The fibers dispersed in composite as single strand or a bundle with a minimal gap between fibers and composite. Conclusion Flexural and compressive strengths of kenaf-reinforced composite resin were lower than the control group, despite some adaptation between kenaf fibers and composite noted. The fibers’ length and diameter were reasonable for the dispersion in the resin matrix; however, additional treatments of kenaf are required for a favorable result.

Evaluation of the Effect of Different Types of Fluoride on Tensile Properties and Surface Roughness of Different Titanium-Based Archwires: An In vivo Study.

Objectives:The purpose of the study was to evaluate the effect of different types of fluoride on tensile properties and surface roughness of titanium based archwires clinically.Materials and methods:Three groups of archwires, namely nickel–titanium (NiTi), heat activated NiTi, and TMA was evaluated clinically. Each group comprised four subgroups, namely as received group, nonfluoride control group, APF gel group (received one application of 1.23% APF gel), and sodium fluoride mouthwash group (patients rinsed twice daily with 0.2% sodium fluoride mouthwash). All the archwires were removed after 3 weeks of clinical use and evaluated for surface roughness with three dimensional optical profiler. Tensile strength and elongation rate was determined with Instron universal testing machine.Results:NiTi, heat activated NiTi, and TMA archwires with APF gel application showed the highest reduction in tensile strength and elongation rate and highest value for surface roughness, followed by sodium fluoride mouthwash group and finally wires without fluoride application. NiTi wires had the highest reduction in tensile strength with APF gel followed by heat activated NiTi and TMA.Conclusion:APF gel with highest concentration of fluoride caused most degradation in the tensile properties and surface roughness of titanium based arch wires.

Influence of the volume of restorative material on the concentration of stresses in the restorative interface.

BackgroundTo evaluate the microtensile strength in the adhesive interface depending on the volume of the composite resin used to restore class I cavities. Material and MethodsForty-eight human third molars received a standardized class I cavity preparation and they were separated into six experimental groups: G1 – single-bottle adhesive system; G2 - bonding system with load; G3 – single-bottle adhesive associated with low-viscosity composite resin; G4 – loaded adhesive associated with low-viscosity composite; G5 - resin-modified glass ionomer associated with single-bottle adhesive; and G6 - resin-modified glass ionomer associated with loaded adhesive. All cavities were restored with a universal restorative composite. After completing the restorations, the samples were stored for seven days in a stove (37°C) and the microtensile bond strength was evaluated by producing slices and applying axial loading in an Instron universal testing machine at a speed of 0.5 mm/min. The thickness of the intermediate layer formed on the cavity floor to verify the relationship between the volume of restorative composite and the concentration of stresses in the buccal wall. With the data obtained in the microtensile strength test, an Analysis of Variance (ANOVA) was performed entirely at random. ResultsDuncan’s test showed that group 4 (Filtek Flow/Optibond Solo Plus) obtained the highest mean of microtensile strength with no statistically significant difference to groups 3 (Filtek Flow/Single Bond), 5 (Vitremer/Single Bond), and 6 (Vitremer/Optibond Solo Plus). It also showed a statistically significant difference to groups 2 (Optibond Solo Plus) and 1 (Single Bond), with no statistical difference between the other groups studied. ConclusionsThe highest mean of microtensile strength was obtained when the volume of the restorative material decreased through the interposition between the material and the adhesive system of a base with low elasticity modulus. Key words:Adhesion, microtensile, composite resin.