Fracture Resistance of Roots Obturated with Resilon and EndoREZ with Self-Adhesive Root Canal Sealers

<sec> <title>Objective:</title> This laboratory study aimed to evaluate the effect of self-adhesive root canal sealers on the fracture strength of root canals filled with Resilon or EndoREZ. </sec> <sec> <title>Materials and Methods:</title> A total of eighty extracted mandibular premolar teeth were selected in this in-vitro study. All teeth were instrumented using a crown-down technique by FlexMaster rotary NiTi files. Specimens were divided into 4 test groups (n = 20) according to the sealer material: RS; RealSeal, RSS; RealSeal SE, MS; MetaSeal, and CG; (control group) zinc oxide eugenol-based sealer. Each main group was distributed into two subgroups (n = 10) according to the filling material either Resilon or EndoREZ and gutta-percha (n = 20) in the control group. Each root was mounted in acrylic resin blocks and subjected to fracture in a universal testing machine. The load values at root specimens fractured were registered in Newton’s and the data were analyzed using two-way analysis of variance and the Tukey HSD test (α = 0.05). </sec> <sec> <title>Results:</title> The two-way analysis of variance analysis indicated that the filling material had a significant effect on the fracture strength of endodontically treated teeth (p < 0.05) but not the sealer materials (p≥.05). Higher mean fracture strength was recorded in MetaSeal and Resilon group (1281.90±200.34 N) and lower mean fracture strength was shown in RealSeal and EndoREZ group (847.55±191.04 N). </sec> <sec> <title>Conclusion:</title> Self-adhesive (fourth-generation) resin sealers increased the fracture strength of root teeth more than self-etching (third-generation) root canal sealers when used with EndoREZ points. </sec>

Pemanfaatan Bahan Alam Anchor sebagai Bahan Konservasi Fosil di Sangiran

Balai Pelestarian Situs Manusia Purba Sangiran telah menggunakan bahan alam anchor sebagai bahan perekat untuk menyambungkan fosil yang patah sejak tahun 2018 setelah melakukan penelitian selama dua tahun yaitu pada tahun 2016 dan pada tahun 2017. Seiring berjalannya waktu penggunaan bahan alam anchor mengalami kerusakan seperti hasil sambungan patah atau retak yang diakibatkan penyimpanan fosil yang kurang tepat. Penelitian ini bertujuan untuk menentukan kekuatan mekanik campuran fosil dan anchor. Penelitian menggunakan rancangan acak lengkap satu faktor dengan variasi perbandingan fosil ukuran 100mesh dan anchor (1:1, 2:1, dan 3:1) dengan dua ulangan. Kemudian melakukan pengujian kuat tekan menggunakan universal testing machine berdasarkan standar ASTM D695-96. Hasilnya menunjukkan nilai kuat tekan tertinggi campuran serbuk fosil dan anchor dengan pada perbandingan 1:1 yaitu 19,996 N/mm2 dan nilai kuat tekan terendah pada perbandingan serbuk fosil dan anchor 3:1 yaitu 12,51 N/mm2. Lem anchor hasil penelitian telah memenuhi persyaratan SNI 06-6049-1999 tentang polivinil asetat emulsi untuk pengerjaan kayu sebagai standar pembanding yaitu memiliki kekuatan rekat minimal 3 N/mm2 dan memiliki pH (3-8).

Compressive Rheological Behavior and Microstructure Evolution of a Semi-Solid CuSn10P1 Alloy at Medium Temperature and Low Strain

Copper–tin alloys are widely used in the machining and molding of sleeves, bearings, bearing housings, gears, etc. They are a material used in heavy-duty, high-speed and high-temperature situations and subject to strong friction conditions due to their high strength, high modulus of elasticity, low coefficient of friction and good wear and corrosion resistance. Although copper–tin alloys are excellent materials, a higher performance of mechanical parts is required under extreme operating conditions. Plastic deformation is an effective way to improve the overall performance of a workpiece. In this study, medium-temperature compression tests were performed on a semi-solid CuSn10P1 alloy using a Gleeble 1500D testing machine at different temperatures (350−440 °C) and strain rates (0.1−10 s−1) to obtain its medium-temperature deformation characteristics. The experimental results show that the filamentary deformation marks appearing during the deformation are not single twins or slip lines, but a mixture of dislocations, stacking faults and twins. Within the experimental parameters, the filamentary deformation marks increase with increasing strain and decrease with increasing temperature. Twinning subdivides the grains into lamellar sheets, and dislocation aggregates are found near the twinning boundaries. The results of this study are expected to make a theoretical contribution to the forming of copper–tin alloys in post-processing processes such as rolling and forging.

Revealing the compressive and flow properties of novel bone scaffold structure manufactured by selective laser sintering technique

Additive manufacturing is revolutionizing the field of medical sciences through its key application in the development of bone scaffolds. During scaffold fabrication, achieving a good level of porosity for enhanced mechanical strength is very challenging. The bone scaffolds should hold both the porosity and load withstanding capacity. In this research, a novel structure was designed with the aim of the evaluation of flexible porosity. A CAD model was generated for the novel structure using specific input parameters, whereas the porosity was controlled by varying the input parameters. Poly Amide (PA 2200) material was used for the fabrication of bone scaffolds, which is a biocompatible material. To fabricate a novel structure for bone scaffolds, a Selective Laser Sintering machine (SLS) was used. The displacement under compression loads was observed using a Universal Testing Machine (UTM). In addition to this, numerical analysis of the components was also carried out. The compressive stiffness found through the analysis enables the verification of the load withstanding capacity of the specific bone scaffold model. The experimental porosity was compared with the theoretical porosity and showed almost 29% to 30% reductions when compared to the theoretical porosity. Structural analysis was carried out using ANSYS by changing the geometry. Computational Fluid Dynamics (CFD) analysis was carried out using ANSYS FLUENT to estimate the blood pressure and Wall Shear Stress (WSS). From the CFD analysis, maximum pressure of 1.799 Pa was observed. Though the porosity was less than 50%, there was not much variation of WSS. The achievement from this study endorses the great potential of the proposed models which can successfully be adapted for the required bone implant applications.

Biaxial Flexural Strength of Different Monolithic Zirconia upon Post-Sintering Processes

Objective Different post-sintering processes are expected to be a reason for alteration in the strength of zirconia. This study evaluated the effect of post-sintering processes on the flexural strength of different types of monolithic zirconia. Materials and Methods A total of 120 classical- (Cz) and high-translucent (Hz) monolithic zirconia discs (1.2 mm thickness and 14 mm in Ø) were prepared, sintered, and randomly divided into four groups to be surface-treated with (1) as-glazed (AG); (2) finished and polished (FP); (3) finished, polished, and overglazed (FPOG); and (4) finished, polished, and heat-treated (FPHT) technique (n = 15). Biaxial flexural strength (σ) was determined on a piston-on-three ball in a universal testing machine at a speed of 0.5 mm/min. Statistical Analysis Analysis of variance, and post hoc Bonferroni multiple comparisons were determined for significant differences (α = 0.05). Weibull analysis was applied for survival probability, Weibull modulus (m), and characteristic strength (σ0). The microstructures were examined with a scanning electron microscope and X-ray diffraction. Results The mean ± standard deviation value of σ (MPa), m, and σ0 were 1,626.43 ± 184.38, 9.51, and 1,709.79 for CzAG; 1,734.98 ± 136.15, 12.83, and 1,799.17 for CzFP; 1,636.92 ± 130.11, 14.66, and 1,697.63 for CzFPOG; and 1,590.78 ± 161.74, 10.13, and 1,663.82 for CzFPHT; 643.30 ± 118.59, 5.59, and 695.55 for HzAG; 671.52 ± 96.77, 3.28, and 782.61 for HzFP; 556.33 ± 122.85, 4.76, and 607.01 for HzFPOG; and 598.36 ± 57.96, 11.22, and 624.89 for HzFPHT. The σ was significantly affected by the post-sintering process and type of zirconia (p < 0.05), but not by their interactions (p > 0.05). The Cz indicated a significantly higher σ than Hz. The FP process significantly enhanced σ more than other treatment procedures. Conclusion Post-sintering processes enabled an alteration in σ of zirconia. FP enhanced σ, while FPOG and FPHT resulted in a reduction of σ. Glazing tends to induce defects at the glazing interface, while heat treatment induces a phase change to tetragonal, both resulted in reducing σ. Finishing and polishing for both Cz and Hz monolithic zirconia is recommended, while overglazed or heat-treated is not suggested.

Low-Cost Force Sensors Embedded in Physical Human–Machine Interfaces: Concept, Exemplary Realization on Upper-Body Exoskeleton, and Validation

In modern times, the collaboration between humans and machines increasingly rises, combining their respective benefits. The direct physical support causes interaction forces in human–machine interfaces, whereas their form determines both the effectiveness and comfort of the collaboration. However, their correct detection requires various sensor characteristics and remains challenging. Thus, this paper presents a developed low-cost sensor pad working with a silicone capsule and a piezoresistive pressure sensor. Its measurement accuracy is validated in both an isolated testing environment and a laboratory study with four test subjects (gender-balanced), and an application integrated in interfaces of an active upper-body exoskeleton. In the material-testing machine, it becomes apparent that the sensor pad generally features the capability of reliably determining normal forces on its surface until a certain threshold. This is also proven in the real application, where the measurement data of three sensor pads spatially embedded in the exoskeletal interface are compared to the data of an installed multi-axis load cell and a high-resolution flexible pressure map. Here, the consideration of three sensor pads potentially enables detection of exoskeletal support on the upper arm as well as “poor” fit conditions such as uneven pressure distributions that recommend immediate system adjustments for ergonomic improvements.

The consistency and reliability of six-strand and four-strand flexor tendon repairs: a comparative porcine cadaveric study

The aim of this study was to compare the consistency and reliability of the six-strand Gan modification of the Lim-Tsai flexor tendon repair with the four-strand Adelaide repair, both with 3-0 sutures and with eight to ten runs of simple 5-0 running peripheral suture as well as the influence of the surgeons’ level of experience on the strength of the repair in a cadaveric animal setup. Thirty-nine surgeons repaired 78 porcine flexor digitorum profundus tendons with either the Adelaide technique (39 tendons) or the modified Lim-Tsai technique (39 tendons). Each repaired tendon was tested in a material testing machine under a single cycle load-to-failure test. The forces were recorded when the gap between the two tendon stumps reached 1 and 2 mm and when irreversible elongation or total rupture occurred. We found no significant differences in gap formation force and yielding strength of the tendons between the two methods. The surgeon’s previous experience in tendon repairs did not improve the consistency, reliability or tensile strength of the repairs. We conclude that if a strong peripheral suture is added, the modified Lim-Tsai repair has the same technical reliability and consistency as the Adelaide repair in term of ultimate loading strength in this test setup.

Fracture Resistance in Non-Vital Teeth: Absence of Interproximal Ferrule and Influence of Preparation Depth in CAD/CAM Endocrown Overlays—An In Vitro Study

There is ample evidence to support the use of endocrowns to restore endodontic teeth. However, the influence of the position of the interproximal margins on fracture strength has not yet been studied. The aim was to determine the relationship between the apicocoronal position of the interproximal restorative margins and fracture resistance in nonvital teeth restored with CAD/CAM endocrown overlays. Forty extracted human maxillary premolars were prepared for endocrown overlay restorations without ferrule on the interproximal aspects and classified according to the position of the interproximal restoration margins in relation to the alveolar crest: 2 mm (group A), 1 mm (group B), 0.5 mm (group C), and 0 mm (group D). Fracture strength was measured using a universal testing machine applying a compressive force to the longitudinal tooth axis. Group A had a mean fracture resistance of 859.61 (±267.951) N, group B 1053.9 (±333.985) N, group C 1124.6 (±291.172) N, and group D 780.67 (±183.269) N, with statistical differences between groups. Group C had the highest values for fracture strength compared to the other groups (p < 0.05). The location of the interproximal margins appears to influence the fracture resistance of CAD/CAM endocrown overlays. A distance of 0.5 mm between the interproximal margin and the alveolar crest was associated with increased fracture resistance.

Fracture Resistance of Primary Zirconia Crowns: An In Vitro Study

In this study, we evaluated the fracture resistance of three commercially available prefabricated primary zirconia crowns and their correlation with dimensional variance. Methods: a total of 42 zirconia crowns were selected from three companies, (1) NuSmile primary zirconia crowns, (2) Cheng Crowns zirconia, and (3) Sprig EZ crowns. The crowns were divided into two groups based on their location in the oral cavity and further divided into subgroups based on the brand. All of the samples were subjected to fracture tests using a universal testing machine. Results: the mean load observed was highest with Cheng Crowns zirconia anterior crowns (1355 ± 484) and the least load was seen with Sprig EZ anterior crowns with a mean load of 339 ± 94. The mean load observed was highest with Cheng Crowns zirconia posterior crowns (1990 ± 485) followed by NuSmile posterior crowns and the least load was seen with Sprig EZ posterior crowns with a mean load of 661 ± 184. Conclusion: the Cheng crowns showed the highest fracture resistance amongst all three groups. Overall, the zirconia crowns (anterior and posterior) tested showed optimum mechanical properties to withstand the masticatory forces.

Axial Compression Behaviour Analysis of Insulated Concrete Form (ICF) Wall Panel with Fibre Cement Board

Nowadays, one of the fastest growing technique is an Insulated Concrete Form (ICF). It has advantages like cost-effective, less maintenance, soundproof, energy-efficient, waterproof and disaster-resistant. ICF wall panels are made by interlocking Fibre Cement Board (FCB) sheet which poured in placed concrete. In this study, the behaviour of the ICF wall panel under axial compression is examined with experimental and analytical methods. ICF wall panels cast with various thickness and dense FCB are tested under axial compression. ICF panels with 1.2gm3/cm dense FCB with changing width of 6mm and 10mm were casted for experimental analysis. The experiments were carried out in an universal testing machine with the capacity of 600 kN. The maximum peak load of 540 kN is observed in FCB of 10mm thick and the maximum displacement of 13mm is observed in FCB80 at the peak load. An analytical investigation is carried with Euler’s crippling load equation and an average variation of 12% is observed between analytical and experimental results. It is concluded that the ICF system of construction provides desirable plastic behaviour against axial compressive loading. Hence ICF is recommended for construction to get the maximum benefits of the wall while it reaches ultimate strain.