Thick Resin Research Articles

Keanekaragaman parasitoid dan predator kutu lak (Laccifer lacca Kerr) di KPH Probolinggo Perum Perhutani Unit II, Jawa Timur

Kutu lak (Laccifer lacca Kerr) (Homoptera: Kerriidae) merupakan serangga yang hidup secara parasitik pada tanaman inangnya. Serangga tersebut menghasilkan resin alami yang kompak dan tebal, yang menempel pada cabang tanaman tempat hidupnya yang biasa disebut lak. Lak cabang merupakan resin alami dari hasil sekresi serangga L. lacca berupa lapisan tebal lak yang membungkus ranting-ranting tanaman inang. Serangan parasitoid dan predator terhadap kutu lak berdampak langsung pada penurunan produktivitas lak. Penelitian ini bertujuan untuk mengidentifikasi parasitoid dan predator yang menyerang kutu lak, dan menghitung tingkat parasitisasi di BKPH Kabuaran dan Taman, KPH Probolinggo, Perum Perhutani Unit II Jawa Timur. Sampel lak cabang diambil dari BKPH Kabuaran dan Taman masing-masing sebanyak 200 sampel lak cabang. Masing-masing lak cabang dimasukkan ke dalam tabung reaksi. Pengamatan parasitoid yang keluar dari lak cabang dilakukan dalam tabung reaksi. Famili parasitoid yang dominan ditemukan, yaitu Aphelinidae, Encyrtidae, dan Eulophidae. Predator yang ditemukan pada kutu lak terdiri atas Famili Lathridiidae (Coleoptera), Cosmopterigidae, dan Noctuidae (Lepidoptera), Nabidae (Hemiptera), serta Chrysopidae (Neuroptera). Jumlah kumulatif parasitoid di lapangan lebih banyak (5.900 individu) dibandingkan dengan di gudang (5.263 individu). Pertambahan individu parasitoid tertinggi dari lapangan dan gudang terjadi pada pengamatan hari ke-7 sampai hari ke-17. Tingkat parasitisasi kutu lak di lapangan dan gudang tergolong tinggi dengan nilai rata-rata sebesar 93% dan 96%. Dapat disimpulkan bahwa kutu lak yang berasal dari lapangan maupun gudang mengalami serangan parasitoid yang sangat tinggi.

Water Hyacinth (Eceng Gondok) As Fibre Reinforcement Composite for Prosthetics Socket

Based on the study of water hyacinth fibres, the results of tensile tests and compressive flexural tests for water hyacinth fibre composites laminated with methyl methacrylate resin as reinforcing materials for the manufacture of trans femoral socket prosthesis, showed there is no significant difference in strength and flexibility between water hyacinth fibres and nylon glass fibre which is more often using in orthopaedics technology.Objectives: This study aims to engineer water hyacinth fibre as reinforcing materials for fabricating trans femoral sockets and perform the structural testing.Study Design: Experimental, bench research.Result: The availability and renewable natural fibres has the potential to reduce hazards for those involved in manufacturing the artificial limb sockets, without reducing and compromising the strength of sockets and benefiting for the users. Wall thickness, fibre direction and fibre-matrix resin lamination played a significant role in socket strength.Conclusions: From this limited study we conclude that the resin and water hyacinth fibre composite socket has the potential to replace the standard layup. Further mechanical and biocompatibility testing as well as a full economic analysis is required. Thus, the use of composites with water hyacinth fibres has the potential to be further developed as an alternative material for socket prosthesis in Indonesia.

Effect of Superficial Air Velocity on Pressure Drop off Fluidized Chamber Experimentally and Computationally

Forming deposits, which remains unutilized and frequently cause ecological issues, could play an important role as energy source to fulfill the energy requirements. Present investigation has been carried out in a cold bed set up to know the hydrodynamic parameters of fluidized bed at atmospheric conditions. To execute this work a round cross-sectional vessel of 0.09 m internal diameter and 1.2 m height was fabricated using 4 mm thick transparent acrylic resin tube. Sand is chosen as an inert bed with mean diameter 0.4, 0.66 and 0.93 mm. Experiments are then conducted at different fluidizing velocities various from 0.272 to 0.544 m/s with three different fuels rice husk, saw dust and groundnut shells. The impact of sand molecule size on fluidization velocity of two components bio-fuel and sand is studied and recommended to use sand molecule of size 0.4 mm for rice husk, saw dust and 0.66 mm sand particle size for ground nut shells. Group of simulations are done through ANSYS FLUENT16; keeping bed conditions is same as that of experiment. The outcomes are presented in the form of contour plots with volume fraction of sand and biomass particles. Experimental data were compared with the simulation the resultsfollowed almost the same trend.

A Combined Amalgam-Composite Filling Technique to Resist Cuspal Fracture

This study was carried out to study a restorative technique of 2 mm thickness of composite resin filling material that bonded, by adhesive (4-META), to MOD cavities (Mesial, Occlusal and Distal surfaces of a tooth) partially filled with amalgam filling materials in upper premolars on the fracture resistance when compared to a sound tooth. Forty freshly sound extracted upper premolars were divided into four groups: the first group of ten sound premolars is subjected to fracture resistance test, the second group of ten premolars with a MOD of half intercuspal distance cavities, which was prepared with long bevel at the cavosurface angle and the teeth were filled with composite resin following incremental technique. The third group of ten teeth were prepared with a box form and butt joint of the same MOD cavities dimension and filled with non-gamma II amalgam. The fourth group of ten premolars with the same MOD cavities dimension are filled with amalgam, a 2 mm thickness of amalgam was removed of the occlusal surface after 24 hours, extended proximally mesially and distally, etch of the exposed enamel, dentin and amalgam was performed, and 4-META adhesive was applied to amalgam and exposed dentin and enamel followed by posterior composite bonded to tooth and amalgam, and cured with light for 40 seconds. The teeth of all groups were tested for fracture resistance. The group I showed the highest resistance to fracture followed by group IV followed by group II and lastly, group III. This study concluded that the use of combined bonded amalgam-composite and tooth structure provided the best technique for filling than cavity only filled with composite or amalgam.

Effect of layering gingiva-shade composite resin on the strength of denture base polymers

Statement of problemAcrylic resin denture base materials, fabricated with either a traditional technique or computer-aided design and computer-aided manufacturing (CAD-CAM) technique, layered with different thicknesses of gingiva-shade composite resin may affect the strength of the definitive prostheses and have not been investigated. PurposeThe purpose of this in vitro study was to assess the flexural strength of acrylic resin denture base materials modified by layering different thicknesses of gingiva-shade composite resin. Material and methodsTwo denture acrylic resins, heat-polymerized type (Lucitone 199) and CAD-CAM prepolymerized type (AvaDent) polymethyl methacrylate (PMMA) resin, were used as the base materials. Three-millimeter–thick specimens were fabricated and prepared according to the ISO 1567 and ISO 20795-1:2013 and were used as the controls. A proprietary gingiva-shade composite resin (GRADIA gum shades) was used to replace different thicknesses (0.5 mm, 1.0 mm, and 1.5 mm) of the denture base materials, giving 4 groups for each tested material (n=16). A 3-point loading test was conducted by using a universal testing machine and a custom fixture with a crosshead speed of 5 mm/min. The maximum fracture loads were recorded, and ultimate flexural strength values were calculated. The collected data were statistically analyzed with ANOVA and the Tukey honestly significant difference (HSD) tests (α=.05). Representative fractured specimens were examined under a stereomicroscope at ×20 magnification and a scanning electron microscope to determine the interface and fracture patterns. ResultsThe mean ±standard deviation of ultimate flexural strengths for the heat-polymerized acrylic resin specimens ranged from 94.79 ±9.89 MPa to 40.34 ±12.79 MPa, and that of the CAD-CAM prepolymerized acrylic resin ranged from 125.98 ±7.96 MPa to 64.16 ±20.77 MPa. Acrylic resin denture base materials after layering with gingiva-shade composite resin had a significantly lower mean fracture load than the controls (P<.05). The Tukey HSD test revealed that the control groups had significantly higher flexural strength values compared with the other tested specimens within each denture acrylic resin group layered with gingiva-shade composite resin (P<.05). The SEM images displayed brittle fracture exhibiting well-defined, flat, compact, and organized surface fractures. ConclusionsThe flexural strengths of CAD-CAM prepolymerized acrylic resins were higher than those of the heat-polymerized denture acrylic resins. The flexural strengths of all 3 thicknesses of the CAD-CAM prepolymerized acrylic resins were greater than 65 MPa.

Electrically tunable liquid-crystal optical and imaging devices operating in the infrared wavelength range of 10 μm band

Homogeneously aligned nematic liquid-crystal (LC) cells and twisted nematic LC cells are fabricated using a Si wafer as a substrate and electrode. Their optical properties are investigated in an infrared (IR) wavelength range of 10 μm band. Transmittance of LC materials is high, and the effective birefringence value is enough to apply the LC to the IR optical devices although it is smaller than that in the visible region. The LC lens cell is fabricated using the Si wafer as a lower electrode-substrate. A flat plate of 1.0 mm thick polyolefin resin on which a hole-patterned aluminum film is deposited is used as an upper substrate and electrode, in order to reduce an absorption loss by the electrode. An IR imaging system composed of the LC lens and a thermography camera is implemented, and a focused thermal image is obtained using a wire-grid IR polarizer. A polarizer-free IR imaging system is also reported.

Fluorine distribution from fluoride-releasing luting materials into human dentin

There are many kinds of dental luting materials (cements) in the market. Some luting materials are fluoride-releasing to prevent secondary caries. The purpose of this study was to evaluate the release of fluorine from fluoride-containing luting materials to adjacent dentin by in-air micro PIXE/PIGE (µPIXE/PIGE) system at Takasaki Advanced Radiation Research Institute. Each extracted human tooth crown was cut to expose a flat dentin surface. A 2-mm thick acrylic resin plate was cemented to each tooth using one of four fluoride-containing luting materials on the dentin surface: Fuji Luting EX (FL); Fuji I (FO); SA Luting plus (SA); and BeautiCem SA (BC). The specimens were sectioned and exposed to automated pH cycling (pH 4.5 and 7.0; simulate oral condition) for 4 or 8 weeks. After pH cycling, calcium and fluorine distributions were analyzed by the µPIXE/PIGE system with a 1.7-MeV 1H+ microbeam. The cumulative fluorine concentration (fluorine uptake) and calcium concentration in each specimen was calculated at a distance of 100 µm from the outermost surface. The results of our study indicated that FL had the highest concentration of fluorine uptake among all test materials in the 8-week group. The other three materials did not differ significantly from each other in terms of fluorine uptake. FL showed higher calcium content than SA in the 8-week group. Findings from this study suggest that the amount of fluorine penetration into dentin is likely to be dependent on the amount of fluoride released from each material, and also related to the amount of calcium present.

Ultrasonic beam induced resistance change (SOBIRCH) method for failure analysis of semiconductor devices encapsulated by mold resin

In the process of the failure analysis for semiconductor devices, various optical methods are applied as techniques to localize faults of the semiconductor devices. Conventional optical techniques often require the decapsulation of the mold resin, since the mold resin is not optically transparent. As a new fault localization technique requiring no decapsulation, the authors are proposing the ultrasonic beam induced resistance change (SOBIRCH) method based on a heating by focused ultrasonic beam. In this report, the signal intensity of the SOBIRCH method for the capsulated samples was discussed through the experimental and the theoretical approaches. By comparing the experiment and the numerical analysis, it was suggested that a certain thickness of the thin mold resin can enhance the intensity of the SOBIRCH signal. Additionally, an expected effect of the standing wave in the thin mold resin was calculated, and a method to make use of the standing wave was proposed.

Quasi-static and dynamic response of oriented strand boards based on balsa wood waste

This work presents an evaluation of the performance of Oriented Strand Boards (OSB) panels based on balsa wood (Ochroma Pyramidale) waste agglomerated with castor oil polyurethane resin. In this study, were evaluated OSB panels with different densities (300 kg/m3, 400 kg/m3 and 650 kg/m3), with 10 mm thickness and castor oil polyurethane resin in different contents (11% and 15%). The OSB panels were preliminary characterized by physical and quasi-static mechanical tests to identify the class of application of this material according to the recommendations of standard EN 300: 2002. Subsequently, the OSB panels were characterized by low velocity impact tests. Panels with the highest density outperformed those with the lowest one in terms of peak force and perforation energy (Ep = 22.88 J). Both properties are clearly influenced by the better compaction of the particles, as confirmed by the higher value of internal adhesion (0.46 MPa), which resulted also in better residual flexural properties after impact, with a reduction in strength of 36% for the samples with 650 kg/m3 compared to about 70% for the samples with the lowest density at an impact energy level equal to 50% of the respective perforation energy.

Effect of Ply Thickness and Matrix Resin on Flexural Properties of Thin Ply CFRP Laminates

Effect of Ply Thickness and Matrix Resin on Flexural Properties of Thin Ply CFRP Laminates

Level Detection of Materials in Nonmetallic Tank by the DC Component of a Microwave Doppler Module

This paper describes a novel level sensor that is noninvasive to nonmetallic tanks and noncontact to materials stored in them. It detects the materials from the outside of a tank by the use of microwave Doppler modules. The output AC component of Doppler modules has been used as moving object detectors. Here, we focus on the output DC component, which is proportional to the intensity of the reflected microwave signals from the stored material. We propose a sensor to detect the level of very low dielectric materials. We build a theoretical model based on multiple reflections of microwaves from the surfaces between different dielectric materials and demonstrate the sensor’s theoretical potential. Experiments were carried out using the sensor to verify its feasibility. The sensor detected levels of Styrene foam with dielectric constant 1.02 from the outside of a 3.0 mm thick acrylic resin tank under optimal conditions. Furthermore, the S/N ratio of the Styrene foam measurement was over 19 dB for the drift noise caused by the change in environmental temperature from 20 °C to 80 °C. The S/N ratio of the change in tap-water’s temperature ranging from 0.5 °C to 77 °C was 18 dB at the reference of 23 °C, and for the change in conductivity ranging from 0.35 to 26 mS/cm was 33 dB.

Clinical Alternatives for the Use of Compactable and Flowable Bulk-Fill Composites: A Step-by-Step Case Report

The use of Bulk-Fill composite resins to perform posterior restorations has been massified in recent years in the different clinical disciplines of Dentistry. This may be due mainly to the simplicity in the application technique of this material as it requires its insertion into the cavity preparation in 4-5mm of composite resin thickness, achieving a considerable reduction of clinical working time. Given the existence of different viscosities of this type of composite resins, certain difficulties have been identified before the selection of each Bulk-Fill material related to the possible combinations that can be made between the different brands available in the market, even when they are used with conventional composite resins. The purpose of the following case report, is to present two step-by-step clinical possibilities using initially, compactable Bulk-Fill composite resin in a single increment for the restoration of a second upper molar, and later, through the combination of Bulk-Fill flowable composite resin together with compactable Bulk-Fill composite resin and a high-refractive-index enamel-like conventional composite resin, for a first upper molar.

Effect of supporting substrate on the failure behavior of a polymer-infiltrated ceramic network material

Statement of problemRestorative materials are cemented on different types of substrates, such as dentin, metal, and glass-fiber posts with composite resin cores. PurposeThe purpose of this in vitro study was to evaluate the failure behavior after cycling fatigue of a polymer-infiltrated ceramic network material (PICN; VITA ENAMIC) cemented on different supporting substrates. Material and methodsPICN plates (N=80) were obtained from computer-assisted design and computer-assisted manufacturing (CAD-CAM) blocks and cemented with a resin cement to 4 different supporting substrates (n=20): (1) human dentin (PICNDen); (2) dentin analog (PICNDenAn); (3) nickel-chromium alloy (PICNNiCr); and (4) composite resin plus fiberglass post (PICNRc). For comparison, the fracture behavior of a feldspathic ceramic (FelDenAn; VITABLOCS Mark II) and an indirect composite resin (ResDenAn; Opallis LAB Resin) cemented to the DenAn substrate was investigated (n=20). Thus, specimens were composed of the restorative material layer (1-mm thick) resin cemented (0.1-mm-thick layer) to a 2-mm-thick supporting substrate. All specimens were subjected to mechanical cycling (MC) using a pneumatic cycling machine (500 000 cycles, 2 Hz, 50 N). Specimens that did not fracture during cycling were tested under compression using a universal testing machine at a cross-head speed of 0.5 mm/min until the sound of the first crack was detected using an acoustic system. Failure data were statistically evaluated using Weibull distribution. Failures were classified as radial crack, cone crack, combined, and catastrophic fracture. ResultsAll FelDenAn specimens were fractured during MC. Only 4 PICNRc specimens survived MC, so their fracture load data were not statistically analyzed. PICNNiCr showed the greatest characteristic load (L0) value, followed by ResDenAn. Groups PICNDenAn and PICNDen showed lower and similar L0 but statistically different Weibull modulus (m). There was a significant relationship between experimental group and failure mode (P<.001). FelDenAn and PICNRc had a higher frequency of radial cracks, whereas PICNNiCr failed from cone cracking. ConclusionsThe supporting substrate influenced the failure behavior of PICN. When the substrate had a higher elastic modulus than the restorative material, better mechanical behavior was observed.

Influence of resin cement thickness and temperature variation on mechanical behavior of dental ceramic fragment restoration

To evaluate the stress behavior of ceramic fragment restoration, varying the thickness of the cement layer and intraoral temperature variation. A solid model of a upper lateral incisor was obtained and a defect at enamel distal/incisal edge was restored with a ceramic fragment. Based on this initial model, 4 different models (M) were built: M1 – absence of cement layer (CL) (0 μm of thickness); M2 – CL with an uniform thickness of 50 μm; M3 – CL with 50 μm at the margin of ceramics and 100 μm in the inner area far from margins; M4 – CL with 50 μm at the margin of ceramics and 200 μm in the inner area far from margins. The environment temperature changed from 5 °C to 50 °C in 4 increments. The finite element analysis was performed. Increase the cement layer thickness generated higher stress levels on ceramic surface in all temperatures, as well as on cement interface. In general hot temperature was the worst scenario for ceramic fragments integrity, since tensile and compressive stress were more intense. The maximum principal stress on ceramic fragment was found 90 MPa for M4 at 50 °C, followed for M3 (87 Mpa). For CL, the peak of stress was found for M3 at 5 °C (47 MPa). Is it possible to conclude that thick resin cement layer contribute to higher stress concentration on ceramic fragment, and extremely hot temperatures increase the risk of structural failure, since both ceramic and \\cl are exposed to higher compressive and tensile stresses.

Effects of Denture Base Thicknesses and Reinforcement on Fracture Strength in Mandibular Implant Overdenture with Bar Attachment: Under Various Acrylic Resin Types.

Objective This study aimed to assess the effect of reinforcement, denture base thickness, and acrylic resin types on dynamic and static fracture strength in mandibular implant overdentures with bar attachment. Materials and Methods One hundred and eight experimental mandibular implant overdentures with bar attachments were fabricated in three main groups, namely unreinforced (control: C), reinforced with unidirectional glass fibers (FR), and Co–Cr cast metal (MR). Each group included denture bases of 2-, 3-, and 4-mm thicknesses and produced with conventional (CA) and high-impact acrylic (HIA) resins. Specimens were thermocycled (5,000 times, 5–55°C) then subjected to a 400,000 cyclic load regime. Unbroken specimens were then loaded until fracture by a universal testing machine. Differences in mean fracture resistance among the groups were compared using the one-way analysis of variance (with post hoc Tukey's honestly significant difference test) and Student's t -tests (α = 0.05). Results Fracture strength increased significantly when the denture base thickness was increased ( p = 0.001 ) . The 2-mm denture base thickness was not enough for reinforcement. The fracture strength of the FR groups was significantly higher than other groups for 3- and 4-mm thicknesses ( p = 0.001). The fracture strength of the HIA resin was significantly higher than CA resin in FR groups ( p = 0.029 and p = 0.001). MR groups showed the weakest fracture strength. Conclusions The 2-mm denture base thickness had sufficient fracture strength without reinforcement and a positive relationship between acrylic resin thickness and fracture resistance was found.

Evaluation of the core thickness and resin cement on the fracture strength of zirconia-based multilayer computer-aided design/computer-aided manufacturing ceramic crowns

Aim: The purpose of this study was to evaluate the effect of thickness of zirconia core and different resin cements on the fracture strength of veneered zirconia crowns designed by multilayer technique. Materials and Methods: Forty metal dies were constructed to replica maxillary molar. Forty zirconia cores (Sirona inCoris ZI) were designed and constructed (inLab 4.4) with different thicknesses. The thickness of zirconia core was selected as 0.5 and 0.7 mm. Forty Feldspathic ceramic (VITABLOCS Mark II) veneers were fabricated (inLab 4.4) onto the zirconia cores. The zirconia cores were divided into two subgroups, and veneers were cemented with one of the following resin cement: self-cure, self-adhesive resin cement with light-cured option (Multilink N), and a dual-cure resin cement (Panavia F 2.0). Then, crowns were cemented to the metal dies. All the specimens were subjected to thermal cycling 5000 times (5°C–55°C ± 2°C, immersion time: 30 s). A universal testing machine was used for fracture strength test at a crosshead speed of 1 mm/min. The data were analyzed with one-way analysis of variance (α = 0.05). Stereomicroscopy was used to evaluate the failure modes and surface structure. Results: Zirconia core thickness and resin cement material affected the fracture strength (P < 0.05). Increase in core thickness increased the fracture strength of multilayer veneer crown (P < 0.05). Higher fracture strength values were obtained with light-cured, self-adhesive cement in both core thicknesses. Conclusion: Although 0.5-mm thickness zirconia cores showed lower flexural strength, it was higher than the maximum loads which may occur clinically (Fmax= 600 N on one tooth). Furthermore, light-cured, self-adhesive resin cement is advisable to increase the fracture strength with different core thickness.

Effect of light absence or attenuation on biaxial flexural strength of dual-polymerized resin cements after short- and long-term storage.

To evaluate whether biaxial flexural strength (BFS) of dual resin cements is affected by light absence or attenuation, storage time, or cements' chemical nature. One hundred and twenty disk-shaped specimens were made from each cement (non-self-adhesive cement and self-adhesive cement) using Teflon molds on a controlled temperature surface (35°C). Specimens were polymerized as follows (N = 30): self-cured, directly light-cured, light-cured at a distance of 6 mm between the light tip and the specimen, and through a 6-mm thick composite resin barrier (indirectly light-cured). Each group was divided (N = 10) for storage purposes (15 minutes, 24 hours, and 6 months). Specimens were placed into a biaxial-flexure jig and a vertical load was applied until failure. The BFS values were subjected to generalized linear models statistical analysis and Weibull distributions (α = 0.05). After 15 minutes aging, neither material achieved enough polymerization to perform the BFS test when polymerized using the self-curing mode. The self-adhesive product demonstrated much lower variation in strength with storage time than did the non-self-curing cement. Attenuated/light-curing reduced BFS values only for 15-minutes storage period for both materials. Flexural strength of the self-adhesive cement was less affected by light absence/attenuation and storage time. Biaxial flexural strength of a self-adhesive resin cement is less sensitive to variation in light application and storage time than is a non-self-adhesive cement.

Pixelated CdZnTe detector based on Topmetal-[formula omitted] readout chip

In order to solve the leakage current saturation of Topmetal-II− and to maintain its low noise, Topmetal-IIa has been designed. The new chip has the same Rolling-Shutter module as Topmetal-II−. It contains a charge-collection electrode and a metal layer surrounding it, called guard ring. This new design contains three different sections. Section A has the same structure as Topmetal-II−, in that the electrode is exposed and guard ring is covered by insulating layer. Section B has both electrode and guard ring exposed. Section C has guard ring exposed but electrode covered by insulating layer. Preliminary experiments show that if coupled with CdZnTe detector, Section C of the Topmetal-IIa chip is capable of solving the leakage current saturation. Meanwhile, the electrode receives induced signal. Moreover, the charge induction efficiency is influenced by several parameters, such as thickness of adhesive epoxy resin, collecting electrode size, etc. Thus, the optimization of parameters for induction efficiency is studied by simulations. According to the simulation results, it can be concluded that thinner epoxy resin thickness and bigger anode size contribute to higher induction efficiency.

Effect of anaerobic cure of self-etch adhesive on degree of conversion and shear bond strength

The main aim was to evaluate the effect of postponing the curing of the adhesive layer until the first layer of composite resin is applied-hereby oxygen-inhibited layer (OIL) formation and its detrimental effect on the degree of conversion (DC) of self-etch adhesives should be prevented. For this purpose, the degree of conversion and shear bond strength of four current market self-etch adhesives were evaluated, assessing the effect of curing the adhesives anaerobically and then under two different thicknesses of composite resin, and compare this to the samples cured alone and in air. The degrees of conversion were obtained by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, after the samples were prepared on a glass slide. The samples were either light-cured in air or anaerobically under a clear matrix strip alone, under 2mm of cured composite resin or under 4mm of cured composite resin. To determine the shear bond strength (SBS), extracted molars were halved and set in acrylic. Prefabricated cured cylinders of composite resin (TPH 3, 2.4mm in diameter) of two different lengths are placed over the adhesives under the following conditions: light-cured conventionally (2-mm-long cylinder) and light-cured anaerobically under the uncured end of the piece of composite resin (using both 2- and 4-mm-long cylinders as separate treatments). After another incubation for 24h at 37°C, the samples were subjected to shearing using the Bisco Shear Bond Strength Tester. The degree of conversion of the one-step self-etch adhesives was not statistically different when cured anaerobically under a clear matrix strip or cured anaerobically under 2mm of composite resin. These results were greater than those cured under 4mm. Shear bond strength between samples cured in air and anaerobically were similar under 2mm of composite resin tubes, while those cured anaerobically under 4mm of resin showed lower shear bond strength. When cured anaerobically, one-step self-etch adhesives show a greater degree of conversion and no significant difference in degree of conversion and shear bond strength when compared to those cured in air under the same thickness of composite resin. The results obtained from DC and SBS analysis show promise in placing the uncured adhesive under the composite resin and curing both the adhesive and restoration material simultaneously.

OSB Panels with Balsa Wood Waste and Castor Oil Polyurethane Resin

This work presents a study for using Balsa wood (Ochroma pyramidale) waste in the production of oriented strand boards (OSB) agglomerated with castor oil polyurethane resin. For this study, were produced OSB panels with different densities (300 kg/m3 and 400 kg/m3), with 10 mm thickness and castor oil polyurethane resin in different contents (11% and 15%). The Balsa wood particles were characterized by physical, chemical and anatomical tests that identified the potential of this by-product as raw material for the production of OSB panels. Subsequently, the thermo-physical-mechanical properties of low density OSB panels produced with Balsa wood waste were determined. The results indicated that panels with a density of 400 kg/m3 and a resin content of 15% obtained a performance that classifies them as OSB type 1—internal and non-structural use panels according to the European Standard EN 300: 2002—OSB—definitions, classification and specifications.