Displaying publications 41 - 60 of 117 in total

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  1. Asma, A.A.A., Rohaya, M.A.W., Juhaida, S., Badiah, B., Zaleha, S.
    Medicine & Health, 2020;15(2):96-107.
    MyJurnal
    Rawatan ortodontik boleh menjejaskan keseimbangan mikrobiota oral yang memainkan peranan utama dalam etiologi penyakit periodontium. Kajian klinikal prospektif ini bertujuan untuk menilai kesihatan periodontal dan profil mikrobiologi pesakit periodontal yang sihat (Kumpulan 1) dan yang telah stabil (Kumpulan 2) selama tiga bulan pertama semasa rawatan ortodontik. Aplian ortodontik atas dan bawah tetap dipasang. Kesihatan periodontium dinilai menggunakan skor plak (PS), pendarahan pada probing (BOP) dan kedalaman poket (PD). 29 tapak telah diambil untuk persampelan plak subgingival. Sampel plak diinokulasikan pada agar Trypticase Soya Darah (TSBA) dan agar Trypticase Soya Bacitracin Vancomycin (TSBV) untuk penilaian aerob, anaerob, bakteria berpigmen hitam (BPH) dan Aggregatibacter actinomycetemcomitans. Semua ukuran diambil sebelum pendakap gigi dipasang (T0), 1 minggu (T1), 1 bulan (T2) dan 3 bulan selepas dipasang pendakap gigi (T3). Secara umumnya, kesihatan periodontium dalam kedua-dua kumpulan hampir sama. Selepas 1 minggu, bilangan aerob adalah lebih tinggi dalam Kumpulan 1 (88%) manakala anaerob adalah lebih tinggi dalam Kumpulan 2 (45%). A. actinomycetemcomitans lebih tinggi dalam Kumpulan 1 pada T0 dan T1 tetapi jauh lebih tinggi dalam Kumpulan 2 di T3. BPH adalah minimal pada setiap masa dengan tiada perbezaan signifikan. Oleh itu, semasa 3 bulan pertama rawatan ortodontik dijalankan, terdapat perubahan ketara dalam bilangan aerob-anaerob pada kedua-dua pesakit periodontal yang sihat dan stabil. Bakteria patogenik akan meningkat semasa rawatan awal ortodontik.

    Matched MeSH terms: Composite Resins
  2. Lui, J.L.
    Ann Dent, 2007;14(1):14-18.
    MyJurnal
    During post crown restoration, the preparation of the post canal can be fraught with difficulties resulting in widening, gouging and transportation of the post canal; sometimes with near root perforation. A technique is described to repair such iatrogenically damaged internal root canal walls using reinforcing resin composite and optic glass fibre posts. The root dentine, resin composite and glass fibres, having similar moduli of elasticity, will result in a repaired root with a ‘monolithic’ structure and possessing numerous desirable characteristics. This repair technique can easily be carried out in one sitting at the chairside thereby allowing the continued serviceability of the iatrogenically compromised root-filled tooth.
    Matched MeSH terms: Composite Resins
  3. Gonzalez, M.A.G., Razak, A.A.A., Khokhar, N.H.
    Ann Dent, 2010;17(1):25-34.
    MyJurnal
    The widespread use of aesthetic fillings has highlighted their advantages and disadvantages. One
    of the most troublesome features of earlier aesthetic materials was the difficulty of finishing the restoration surface to decrease adherence of food debris. The rougher the finished surface, the greater the possibility of bacterial accumulation and discolouration of restoration along the restoration margin with secondary caries formation. Aside from these clinical implications, patients are highly discerning and could detect roughness of 0.30 μm with their tongue. The aesthetic restoration should mimic the appearance of natural dentition and should have an enamel-like appearance. An increased demand for superior aesthetics from composite resin has increased the
    demand for more eff icient and simple polishing techniques. The development of nanocomposites has given a new perspective to the polishing of composite resins. Nanocomposites claim the advantage of improved gloss, optical characteristics and reduced wear. To date, results of in vitro studies have been equivocal regarding the most efficient and effective polishing system. There is variation in the effects of different finishing and polishing instruments on the surface roughness due to great diversity in size, shape, composition and distribution of the filler particles of composite resins, type of resin and a wide variety of finishing and polishing instruments. This paper will
    review the different factors that affect polishing techniques used in achieving the desired polish on
    composite resin restorations.
    Matched MeSH terms: Composite Resins
  4. Yahya, N.A., Lim, K.H.D.
    Ann Dent, 2008;15(2):89-93.
    MyJurnal
    Direct composite veneers can be used to mask tooth discolorations and/or to correct unaesthetic tooth forms and/or positions. However, these type of restorations are often regarded as one of the most challenging in aesthetic dentistry presumably due to the extent of natural tooth structure that must be recreated. This paper discusses easy application techniques and tips for Ceram.X Duo™, a nano ceramic composite restorative material. Its natural shading system allows the restoration of tooth with both dentine and enamel shade and transforms it into a final direct veneer restoration that mimics a natural tooth.
    Matched MeSH terms: Composite Resins
  5. Farahiyah Mohamad Taib, Zuryati Ab Ghani, Dasmawati Mohamad
    MyJurnal
    Ten percent carbamide peroxide is an effective, safe home bleaching agent. Higher concentrations
    are more effective, but there are mixed reports on their hardness and surface roughness effects on resin composites. To evaluate the effect of home bleaching agents; Opalescence Now 10% carbamide peroxide (Ultradent Products, USA) and Perfect Bleach 17% carbamide peroxide (Voco,
    Germany) on the surface hardness of microhybrid resin composites; Filtek Z250 (3M ESPE, USA) and Point 4 (Kerr, USA) and their surface roughness of selected treatment. Thirty specimens were prepared using acrylic moulds (4mm diameter x2mm thick). N=5 controls placed in distilled water for 14 days.N=5 treated with Opalescence, and n=5 treated with Perfect Bleach for 2 hours every day for 14 days. Surface hardness was tested using Vickers hardness tester FV-7 (Future Tech Corp, Japan). Data analyzed with Mann-Whitney test with (P
    Matched MeSH terms: Composite Resins
  6. Ahmad Mahmood, Aws H. Ali Al-Kadhim, Zaripah Wan Bakar, Adam Husein
    Malaysian Dental Journal, 2011;32(1):12-16.
    MyJurnal
    Evaluation of the mechanical behaviour of restoration dental materials is essential to understand their performance under different load conditions and to estimate their durability under clinical oral function. Restorative materials and dental tissues like other materials by having specific mechanical properties, such as static strength (i.e. compressive strength, tensile strength, flexural strength) and dynamic strength (i.e. fatigue strength). The selection of proper mechanical test type depends on the goals that the study claims to define. On such basis, the mechanical test can be chosen correctly. Laboratory studies should be designed as replications of the clinical oral circumstances to measure the mechanical and physical properties of a material and any arbitrary choices in the design of the study may result in large variations of data.
    Matched MeSH terms: Composite Resins
  7. Abd Rahman, R., Mohamad, D., Ab Ghani, Z., Hasan, H., Abdullah, N.A.
    MyJurnal
    The objective of the study was to asses the adhesion of Streptococcus mutans on nanofilled and microfilled composite resin and glass ionomer cement restorative materials. Glass ionomer cements; KetacTM N100 (nanofilled) and Fuji IITM LC (microfilled) and composite resins; FiltekTM Z350 (nanofilled) and FiltekTM Z250 (microhybrid) were packed in acrylic mould of 2 mm thickness and 5 mm diameter. All samples were light-cured and polished with Sof-Lex discs. All materials were cultured with the exponential phase of S. mutans cultivation. Surface roughness values were assessed using Atomic Force Microscope (AFM, Ambios, USA) at time intervals (7hrs, 24 hrs, 7 days, 14 days and 21 days). The morphology of S. mutans on materials was observed after 24 hour incubation of S. mutan on materials under Scanning Electron Microscope (SEM, Quanta FEG 450). Within groups, results showed that both nanofilled materials had lower surface roughness and less adhesion of S. mutans compared to microfilled materials. This study would enhance the clinical knowledge especially in aesthetic area and improve the longevity of the dental restoration.
    Matched MeSH terms: Composite Resins
  8. Salim NA, Muttlib NAA, Alawi R, Rahman NA, Ariffin Z
    Acta Stomatol Croat, 2018 Sep;52(3):218-226.
    PMID: 30510297 DOI: 10.15644/asc52/3/5
    Objective: This study aimed to compare the difference in marginal dye penetration between everStick, Parapost XP, Parapost fiber white and control groups under gradual loading.

    Materials and Methods: Sixty-eight human maxillary permanent incisors were divided into four groups. Each specimen was endodontically treated with step-back technique and prepared for each post system according to experimental groups, subsequently cemented in the canal. Composite resin cores were built and laboratory fabricated metal crowns were cemented. All specimens except those in the control group were subjected to thermal cycling. All groups were subjected to gradual loading from 0N-50N for 100 cycles. Specimens were sectioned transversely and the depths of dye penetration along the post were measured. Data were entered in SPSS ver. 22 and analyzed using two-way ANOVA test.

    Results: There was no significant difference in marginal dye penetration between each group (p-value>0.05). However, there was a significant difference in percentage of marginal dye penetration between all groups (p-value<0.05); post-hoc comparison showed significant difference between Fiber White and Control groups (p-value=0.009).

    Conclusion: All the groups showed dye penetration but the percentage was significant only between Parapost Fiber White and the control groups.

    Matched MeSH terms: Composite Resins
  9. Ibrahim Ijang, Mohd Cairul Iqbal Mohd Amin, Bukhori Abu Bakar
    Penggunaan formulasi tablet pelepasan tertahan untuk dadah anti-inflamatori bukan steroid (DAIBS) seperti aspirin berupaya melindungi lapisan perut dari kesan buruk jus asid tubuh. Kajian ini dilakukan untuk menilai keberkesanan formulasi tablet matriks pelepasan tertahan dengan kepelbagaian kepekatan polimer bersama ketoprofen sebagai model. Tablet dibangunkan dengan menggunakan kaedah granulasi basah yang terdiri daripada polimer hidrofilik (hidroksipropil metilselulosa), polimer hidrifobik bersandar pada pH (Eudragit L100-55) dan polimer tak bersandar pada pH (Eudragit R100) sebagai bahan asas pembentukan matriks pada kepekatan 10, 20 dan 30%b/b. Semua formulasi dimampatkan dengan menggunakan mesin pentabletan yang mempunyai penebuk berbentuk cembung bersaiz 10 mm. Tablet yang terhasil diuji daripada segi keseragaman berat, kekerasan, kerapuhan, ketebalan, peratus kandungan dadah dan kajian pelepasan in vitro menggunakan kaedah BP 2007. Hasil menunjukkan kadar pelepasan dadah dikawal oleh jenis dan kepekatan polimer di dalam formulasi matriks. Secara umumnya peningkatan kepekatan kandungan polimer di dalam tablet matriks didapati mengurangkan kadar pelepasan dadah. Perbandingan polimer melalui kepekatan yang sama menggunakan t50%, pula mendapati terdapat perbezaan statistik bermakna (p<0.05) pada kadar pelepasan dadah. Berdasarkan kepada pelepasan dadah dalam kajian in vitro, polimer hidrofobik bersandar pada pH (Eudragit L100-55) menunjukkan profil pelepasan dadah secara tertib sifar yang terbaik berbanding polimer yang lain.
    Matched MeSH terms: Composite Resins
  10. Zal U’yun Wan Mahmood, Che Abd Rahim Mohamed, Zaharudin Ahmad, Abdul Kadir Ishak
    Kajian ini dijalankan untuk melihat variasi taburan 210Po dan 210Pb melalui profil menegak aktivitinya, serta nisbah aktiviti 210Po/210Pb di dalam teras sedimen yang diambil di beberapa stesen persampelan pesisir pantai perairan Sarawak. Didapati profil taburan radionuklid tersebut dalam teras sedimen adalah berubah-ubah mengikut lokasi persampelan dan telah dibuktikan melalui analisis ANOVA yang menunjukkan bahawa terdapat perbezaan bererti pada 95% aras keyakinan bagi aktiviti 210Po (p = 0.000), 210Pb (p = 0.035) dan 210Po/210Pb (p = 0.000) di semua lokasi kajian. Secara umumnya, aktiviti 210Po dan 210Pb yang diukur masing-masing dalam julat 337 ke 2460 Bq/kg, 11 ke 84 Bq/kg di SR 01; 224 ke 2008 Bq/kg, 6 ke 80 Bq/kg di SR 02; 119 ke 1595 Bq/kg, 6 ke 84 Bq/kg di SR 03; 241 ke 2294 Bq/kg, 5 ke 82 Bq/kg di SR 04 dan 175 ke 1340 Bq/kg, 4 ke 44 Bq/kg di SR 05. Merujuk kepada julat tersebut, didapati aktiviti 210Po adalah lebih tinggi daripada aktiviti 210Pb dengan purata nisbah 210Po/210Pb di semua stesen adalah melebihi satu, iaitu dalam julat 20 ke 35. Variasi profil taburan radionuklid tersebut dipercayai dipengaruhi oleh beberapa faktor sekitaran dan telah dibuktikan terdapat korelasi yang kuat di antara taburan radionuklid dengan komposisi sedimen jenis kelodak (210Po:r = 0.701 dan 210Pb: r = 0.648), kedalaman air (210Po: r = -0.647) dan jarak stesen dari daratan (210Po: r = 0.746 dan 210Pb: r = 0.975). Oleh itu, dapat disimpulkan bahawa faktor-faktor tersebut merupakan penyumbang utama ke atas perubahan yang berlaku kepada taburan 210Po dan 210Pb.
    Matched MeSH terms: Composite Resins
  11. Normaliza Ab. Malik, Seow LL, Normastura Abd. Rahman, Marhazlinda Jamaludin
    Sains Malaysiana, 2013;42:45-51.
    This study was carried out to evaluate the microleakage of Class II cavities restored with various types of lining materials. Four types of composite resins (Esthet-X-Denstply, USA, FiltekTMZ350-3M ESPE, USA, Beautifil- Shofu, Japan and Solare P-GC, Japan) were used and the lining were the Fuji IXGP (GC, Japan), the Beautifil flow (Shofu, Japan), the FiltexTMZ350 flow (3M ESPE, USA) and the Esthet-X flow (Denstply, USA). All the specimens were thermocycled and immersed in 0.5% basic fuschin dye for 24 h. The microleakage was scored using the ISO microleakage scoring system. The data were entered using SPSS version 12.0 and analyzed using STATA software programme. This study showed that none of the materials used in this study was able to eliminate microleakage. However, it was shown that the glass ionomer cement was better in reducing the incident of microleakage at the cervical margin. Among the flowable composite resin, FiltexTMZ350 flow showed less microleakage at the cervical margin.
    Matched MeSH terms: Composite Resins
  12. Rizal S, Fizree HM, Hossain MS, Ikramullah, Gopakumar DA, Wan Ni EC, et al.
    Heliyon, 2020 Mar;6(3):e03550.
    PMID: 32190763 DOI: 10.1016/j.heliyon.2020.e03550
    This study was conducted to determine the influence of the oil palm boiler ash (OPBA) reinforcement on the microstructural, physical, mechanical and thermal properties of epoxy polymer composites. The chemical composition analysis of OPBA revealed that it contains about 55 wt.% of SiO2 along with other metallic oxides and elements. The surface morphology of OPBA showed angular and irregular shapes with porous structures. The influence of OPBA as a reinforcement in epoxy composite was studied with varying filler loadings (10-50 wt.%) and different particle sizes (50-150 μm). The result showed that the incorporation of OPBA in composites has improved the physical, mechanical and thermal properties of the epoxy matrix. The highest physical and mechanical properties of fabricated composites were attained with 30 wt.% loading and size of 50 μm. Also, thermal stability and the percentage of char residue of the composite increased with increasing filler loading. Furthermore, the contact angle of OPBA reinforced epoxy composites increased with the increase of filler loading. The lowest value of the contact angle was obtained at 30 wt.% of filler loading with the OPBA particle size of 50 μm. The finding of this study reveals that the OPBA has the potential to be used as reinforcement or filler as well as an alternative of silica-based inorganic fillers used in the enhancement of mechanical, physical and thermal properties of the epoxy polymer composite.
    Matched MeSH terms: Composite Resins
  13. Elmi Sharlina MS, Azwan Mat Lazim, Yaacob WA
    Sains Malaysiana, 2017;46:1549-1555.
    Kanji Dioscorea pentaphylla telah diubah suai dengan pensulfatan dan peneutralan bagi menghasilkan natrium
    kanji sulfat. Tindak balas pensulfatan dilakukan dengan asid sulfurik dalam etanol dan air pada suhu 0o
    C. Darjah
    penukargantian dikira berdasarkan peratus karbon dan sulfur yang ditentukan menggunakan penganalisis unsur CHNS.
    Natrium kanji sulfat yang mempunyai darjah penukargantian dan peratus nisbah berat hasil yang tinggi dipilih dan
    dicirikan dengan spektrum transformasi Fourier inframerah (FT-IR) dan profil pembelauan sinar-X (XRD). Kehadiran
    dua puncak getaran regangan C-O-S dan S=O dalam spektrum FT-IR dan puncak berbeza yang terhasil dalam corak
    difraktogram XRD membuktikan tindak balas berlaku pada struktur kanji. Sifat termal juga ditentukan dengan kalorimeter
    pengimbas pembezaan (DSC) dan analisis termogravimetri (TGA). Natrium kanji sulfat yang dihasilkan mempunyai
    kestabilan termal yang baik kerana mempunyai suhu penguraian pada 265o
    C. Natrium kanji sulfat ini sesuai dijadikan
    bahan tambahan dalam penghasilan hidrogel, organogel dan filem dengan sifat anionik kerana degradasi tidak terjadi
    di bawah suhu ini.
    Matched MeSH terms: Composite Resins
  14. Chadda H, Naveen SV, Mohan S, Satapathy BK, Ray AR, Kamarul T
    J Prosthet Dent, 2016 Jul;116(1):129-35.
    PMID: 26873771 DOI: 10.1016/j.prosdent.2015.12.013
    STATEMENT OF PROBLEM: Although the physical and mechanical properties of hydroxyapatite-filled dental restorative composite resins have been examined, the biocompatibility of these materials has not been studied in detail.

    PURPOSE: The purpose of this in vitro study was to analyze the toxicity of acrylate-based restorative composite resins filled with hydroxyapatite and a silica/hydroxyapatite combination.

    MATERIAL AND METHODS: Five different restorative materials based on bisphenol A-glycidyl methacrylate (bis-GMA) and tri-ethylene glycol dimethacrylate (TEGDMA) were developed: unfilled (H0), hydroxyapatite-filled (H30, H50), and silica/hydroxyapatite-filled (SH30, SH50) composite resins. These were tested for in vitro cytotoxicity by using human bone marrow mesenchymal stromal cells. Surface morphology, elemental composition, and functional groups were determined by scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and Fourier-transformed infrared spectroscopy (FTIR). The spectra normalization, baseline corrections, and peak integration were carried out by OPUS v4.0 software.

    RESULTS: Both in vitro cytotoxicity results and SEM analysis indicated that the composite resins developed were nontoxic and supported cell adherence. Elemental analysis with EDX revealed the presence of carbon, oxygen, calcium, silicon, and gold, while the presence of methacrylate, hydroxyl, and methylene functional groups was confirmed through FTIR analysis.

    CONCLUSIONS: The characterization and compatibility studies showed that these hydroxyapatite-filled and silica/hydroxyapatite-filled bis-GMA/TEGDMA-based restorative composite resins are nontoxic to human bone marrow mesenchymal stromal cells and show a favorable biologic response, making them potential biomaterials.

    Matched MeSH terms: Composite Resins/adverse effects*; Composite Resins/therapeutic use; Composite Resins/chemistry
  15. Thiyab, Amar M., Mahmood, Nik Zarina N., Hassan, Mohamed Ibrahim A.
    MyJurnal
    Objectives: The aim of the study is to evaluate the effect of the time and instant coffee solution on the color stability of three types of composite resin based veneer systems. Materials and Methods: 24 composite resin veneer samples were selected and divided into three groups: two groups of prefabricated veneers (Edelweiss, Ultradent Inc™ (EDL) and Componeer, Coltène/ Whaledent AGTM (CMP)) and one group of laboratory made (Nexco, Ivoclar Vivadent (NEX)) veneer system were tested (n=8). Specimens were prepared and stored in staining solution (instant coffee) and assessed color changes with Minolta spectrophotometer every three days for a period of 27 days, after which color differences (ΔE*) were calculated. Data collection and analysis was done using one-way ANOVA and Student’s t-test (α=0.05). Results: One-way ANOVA revealed a significant difference in color stability between the two veneer systems. NEX group veneer system exhibited the highest color stability (ΔE*= 0.73 ± 0.5) as compared to prefabricated veneer groups (EDL 10.07 ± 5.15, CMP 7.41 ± 4.64) with p value
    Matched MeSH terms: Composite Resins
  16. Karimzadeh A, R Koloor SS, Ayatollahi MR, Bushroa AR, Yahya MY
    Sci Rep, 2019 10 31;9(1):15763.
    PMID: 31673118 DOI: 10.1038/s41598-019-51904-4
    This study investigates the capacity of the nano-indentation method in the mechanical characterization of a heterogeneous dental restorative nanocomposite using experimental and computational approaches. In this respect, Filtek Z350 XT was selected as a nano-particle reinforced polymer nanocomposite with a specific range of the particle size (50 nm to 4 µm), within the range of indenter contact area of the nano-indentation experiment. A Sufficient number of nano-indentation tests were performed in various locations of the nanocomposite to extract the hardness and elastic modulus properties. A hybrid computational-experimental approach was developed to examine the extracted properties by linking the internal behaviour and the global response of the nanocomposite. In the computational part, several representative models of the nanocomposite were created in a finite element environment to simulate the mechanism of elastic-plastic deformation of the nanocomposite under Berkovich indenter. Dispersed values of hardness and elastic modulus were obtained through the experiment with 26.8 and 48.5 percent average errors, respectively, in comparison to the nanocomposite properties, respectively. A disordered shape was predicted for plastic deformation of the equilateral indentation mark, representing the interaction of the particles and matrix, which caused the experiment results reflect the local behaviour of the nanocomposite instead of the real material properties.
    Matched MeSH terms: Composite Resins
  17. Zhalehrajabi E, Lau KK, Ku Shaari KZ, Zahraee SM, Seyedin SH, Azeem B, et al.
    Materials (Basel), 2019 Jul 20;12(14).
    PMID: 31330846 DOI: 10.3390/ma12142320
    Granulation is an important step during the production of urea granules. Most of the commercial binders used for granulation are toxic and non-biodegradable. In this study, a fully biodegradable and cost-effective starch-based binder is used for urea granulation in a fluidized bed granulator. The effect of binder properties such as viscosity, surface tension, contact angle, penetration time, and liquid bridge bonding force on granulation performance is studied. In addition, the effect of fluidized bed process parameters such as fluidizing air inlet velocity, air temperature, weight of primary urea particles, binder spray rate, and binder concentration is also evaluated using response surface methodology. Based on the results, binder with higher concentration demonstrates higher viscosity and higher penetration time that potentially enhance the granulation performance. The viscous Stokes number for binder with higher concentration is lower than critical Stokes number that increases coalescence rate. Higher viscosity and lower restitution coefficient of urea particles result in elastic losses and subsequent successful coalescence. Statistical analysis indicate that air velocity, air temperature, and weight of primary urea particles have major effects on granulation performance. Higher air velocity increases probability of collision, whereby lower temperature prevents binder to be dried up prior to collision. Findings of this study can be useful for process scale-up and industrial application.
    Matched MeSH terms: Composite Resins
  18. Alhajj MN, Salim NS, Johari Y, Syahrizal M, Abdul-Muttlib NA, Ariffin Z
    Acta Stomatol Croat, 2020 Sep;54(3):263-272.
    PMID: 33132389 DOI: 10.15644/asc54/3/4
    Objective: Endodontically treated teeth may require posts for retaining the core and replacing the coronal structures that have been lost. The objective of this study was to evaluate and compare the push-out bond strength between different types of post cemented with different types of luting cement at different types of root level.

    Materials and Methods: In this in-vitro study, a total of 48 single-rooted permanent human teeth were decoronated, and the roots were treated endodontically. Following post space preparation, the sample was divided into four groups (n= 12 each) based on the types of post and cement. Two different types of post [GC everStick®POST (ES) and Parapost® Fiber LuxTM (PF)], and two different types of cement [G-CEMTM (G), and RelyXTM Unicem (R)] were used according to the manufacturer's instructions. All roots were sectioned at the coronal and middle thirds with a thickness of 3±0.1mm. The Push-out bond strength (PBS) test was performed using a universal testing machine at a cross-head speed of 0.5mm/ min. The bond strength values were recorded, and the data were analyzed using the SPSS program. Apart from descriptive statistics, three-way ANOVA was used for the interaction of the independent variables (post, cement, and root level). For differences between the groups, the Mann-Whitney U test was used. A P-value of less than 0.05 was considered significant for all analyses.

    Results: Push-out bond strength of samples at the middle level (11.38±10.31 MPa), with PF posts (11.18±9.98 MPa), and of those luted with RelyXTM Unicem cement (13.26±8.73 MPa) was higher than that of their counterparts. The PBS means of RelyXTM Unicem cement at both root levels were much higher than PBS means of G-CEMTM cement. Three-way ANOVA test revealed a significant effect for each variable with a higher effect of cement (Sum of Squares= 1310.690; P< 0.001). No significant difference (P= 0.153) was found between the coronal and middle parts and between ES and PF posts (P= 0.058). However, a highly significant difference (P< 0.001) was found between RelyXTM Unicem and G-CEMTM cements.

    Conclusion: The type of cement had a significant effect on push-out bond strength with RelyXTM Unicem which had higher values than G-CEMTM. However, the type of post and root level had no significant effect on PBS, although Parapost® Fiber LuxTM and middle root level had higher values than their counterparts.

    Matched MeSH terms: Composite Resins
  19. Ali A, Andriyana A, Hassan SBA, Ang BC
    Polymers (Basel), 2021 Apr 29;13(9).
    PMID: 33947012 DOI: 10.3390/polym13091437
    The development of advanced composite materials has taken center stage because of its advantages over traditional materials. Recently, carbon-based advanced additives have shown promising results in the development of advanced polymer composites. The inter- and intra-laminar fracture toughness in modes I and II, along with the thermal and electrical conductivities, were investigated. The HMWCNTs/epoxy composite was prepared using a multi-dispersion method, followed by uniform coating at the mid-layers of the CF/E prepregs interface using the spray coating technique. Analysis methods, such as double cantilever beam (DCB) and end notched flexure (ENF) tests, were carried out to study the mode I and II fracture toughness. The surface morphology of the composite was analyzed using field emission scanning electron microscopy (FESEM). The DCB test showed that the fracture toughness of the 0.2 wt.% and 0.4 wt.% HMWCNT composite laminates was improved by 39.15% and 115.05%, respectively, compared with the control sample. Furthermore, the ENF test showed that the mode II interlaminar fracture toughness for the composite laminate increased by 50.88% and 190%, respectively. The FESEM morphology results confirmed the HMWCNTs bridging at the fracture zones of the CF/E composite and the improved interlaminar fracture toughness. The thermogravimetric analysis (TGA) results demonstrated a strong intermolecular bonding between the epoxy and HMWCNTs, resulting in an improved thermal stability. Moreover, the differential scanning calorimetry (DSC) results confirmed that the addition of HMWCNT shifted the Tg to a higher temperature. An electrical conductivity study demonstrated that a higher CNT concentration in the composite laminate resulted in a higher conductivity improvement. This study confirmed that the demonstrated dispersion technique could create composite laminates with a strong interfacial bond interaction between the epoxy and HMWCNT, and thus improve their properties.
    Matched MeSH terms: Composite Resins
  20. Yap AU, Ong JE, Yahya NA
    J Mech Behav Biomed Mater, 2021 01;113:104120.
    PMID: 33086137 DOI: 10.1016/j.jmbbm.2020.104120
    OBJECTIVES: This study determined the effects of self-adhesive resin coatings on viscoelastic properties of highly viscous glass ionomer cements (HVGICs) using dynamic mechanical analysis.

    MATERIALS AND METHODS: The HVGICs evaluated were Zirconomer [ZR] (Shofu), Equia Forte [EQ] (GC) and Riva [RV] (SDI). Sixty specimens (12mm x 2mm x 2mm) of each material were fabricated using customized Teflon molds. After initial set, the specimens were removed from their molds, finished, measured and randomly divided into 3 groups of 20. Half the specimens in each group were left uncoated while the remaining half was covered with the respective manufacturers' resin coating. The specimens were subsequently conditioned in distilled water, artificial saliva or citric acid at 37°C for 7 days. The uncoated and coated specimens (n=10) were then subjected to dynamic mechanical testing in flexure mode at 37°C with a frequency of 0.1 to 10Hz. Storage modulus, loss modulus and loss tangent data were subjected to normality testing and statistical analysis using one-way ANOVA/Scheffe's post-hoc test and Ttest at significance level p<0.05.

    RESULTS: Mean storage modulus ranged from 1.39 ± 0.36 to 10.80 ± 0.86 GPa while mean loss modulus varied from 0.13 ± 0.03 to 0.70 ± 0.14 GPa after conditioning in the different mediums. Values for loss tangent ranged from 39.4 ± 7.75 to 213.2 ± 20.11 (x10 -3 ). Significant differences in visco-elastic properties were observed between mediums and materials. When conditioned in distilled water and artificial saliva,storage modulus was significantly improved when ZR, EQ and RV were uncoated. Significantly higher values were, however, observed with resin coating when the materials were exposed to citric acid.

    CONCLUSION: The visco-elastic properties of HVGICs were influenced by both resin coating and chemical environment.

    Matched MeSH terms: Composite Resins
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