فهرست مطالب

Dental Biomaterials - Volume:4 Issue: 4, 2017

Journal of Dental Biomaterials
Volume:4 Issue: 4, 2017

  • تاریخ انتشار: 1396/10/09
  • تعداد عناوین: 5
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  • Farahnaz Sharafeddin, Mohammad Reza Azar, Negar Feizi, Raha Salehi* Pages 454-460
    Statement of problem: Hardness of restorative materials like glass-ionomer is an important factor in the longevity of restoration.
    Objectives
    The aim of this study was to evaluate the microhardness of glass-ionomer modified with different materials.
    Materials And Methods
    Sixty disk-shaped specimens were examined in six groups in this study, including conventional glass-ionomer (Shofu, Japan), zirconia-reinforced glass-ionomer (Zirconomer, Shofu, Kyoto, Japan), silver-reinforced glass-ionomer (HI-DENSE XP, Shofu, Kyoto, Japan) and mixture of these three types of glass-ionomer with 20 wt% of microhydroxyapatite (Sigma-Aldrich, St. Louis, USA). All the specimens were stored in deionized water for 24 hours. Then Vickers microhardness test was carried out and the results were analyzed by using two-way ANOVA test and paired t-test (P
    Results
    Zirconia-reinforced glass-ionomer with microhydroxyapatite exhibited significantly higher microhardness in comparison with other groups (P
    Conclusions
    Incorporation of 20% microhydroxyapatite to zirconia-reinforced glass-ionomer can improve microhardness.
    Keywords: Microhardness, Glass-ionomer, Zirconia-reinforced glass-ionomer, Silver-reinforced glass-ionomer, Microhydroxyapatite
  • Najmeh Movahhedian, Shoaleh Shahidi*, Mehdi Bahadori Jahromi Pages 461-467
    Statement of problem: Retro-molar canal (RMC) is of clinical significance because of its neurovascular content, which may be at risk of damage during the surgical procedures of the area.
    Objectives
    The aim of the present study was to evaluate the frequency and anatomic characteristics of RMC by using cone beam computed tomography (CBCT).
    Materials And Methods
    The sample of this study consisted of 500 CBCT images (1000 sides), evaluated for the presence, type, and width of RMC. The canals were categorized into five groups based on their course as A1 (vertical), A2 (vertical with a horizontal branch), B1 (curved), B2 (curved with a horizontal branch), and C (horizontal).
    Results
    The study showed that 57 (11.4%) subjects and 67 (6.7%) sides had RMC in which 47 (9.4 %) were unilateral and 10 (2%) were bilateral. There was no statistically significant difference between male and female individuals in the occurrence of RMC (10.2% and 12.7%, respectively) (P-value=0.387). The most common morphologic types were B1 (50.7%) and A1 (23.9%), while A2 (3%) and B2 (4.5%) were the least frequent types. The mean width of the mandibular canal and RMC were 3.51 ± 0.55 mm and 1.30 ± 0.47 mm, respectively. These dimensions were not significantly influenced by gender (P-value=0.440, 0.569, respectively).
    Conclusions
    The results of the present investigation showed that the RMC was a common anatomic structure. Therefore, because of its clinical significance, it is highly recommended that dental practitioners consider this structure in pre-surgical evaluations of the region in order to avoid related complications.
    Keywords: CBCT, Mandibular anatomy Retromolar canal, Accessory canal
  • Parnian Alizadeh Oskoee, Mohammad Esmaeel Ebrahimi Chaharom, Mehdi Abed Kahnemui, Narmin Mohammadi, Fatemeh Pournaghi Azar*, Hafez Vahedpour, Maryam Saadat Pages 468-474
    Statement of problem: Many efforts have been made to solve the problem of composite resin adaptation and reduce microleakage.
    Objective
    The aim of the present study was to evaluate the effect of preheating of silorane-based composite resins before photo-polymerization on gap formation at the margins of Class V restorations.
    Materials And Methods
    Standard Class V cavities were prepared on the labial surfaces of 46 sound bovine incisor teeth. The teeth were divided into two groups. In group 1, after application of the bonding agent of the silorane system, the cavities were restored with Filtek silorane-based composite resin stored at room temperature. In group 2, before restoring the cavities, the silorane-based composite resin was heated in a warm water bath at 54ºC for 10 minutes. After 48 hours of storage in distilled water, teeth were thermocycled and sectioned bucco-lingually. Then the gaps of tooth‒restoration interfaces in both incisal and gingival margins at three external, middle and internal areas were measured using a stereomicroscope. After calculation of means and standard deviations, data were analyzed with two-factor ANOVA at α=0.05.
    Results
    The mean marginal gaps in non-preheated and preheated groups were 10.66±2.39 and 7.62±2.05 µm, respectively, with a statistically significant difference (P
    Conclusions
    Heating silorane-based composite resin before light curing resulted in decreasing the gap sizes at tooth‒restoration interfaces in Class V cavities.
    Keywords: Gap formation, Preheating, Silorane-based composite resin
  • Mohammad Saleh Khaghaninejad, Ali Peyravi*, Amir Khosravifard, Elham Peyravi, Hamid Reza Eftekharian, Mahmoud Reza Peyravi Pages 475-483
    Statement of Problem: Bite force is generated due to the consonance between different parts of the masticatory system. In dentistry, measurement of the bite force is quite common through several methods and devices.
    Objective
    The aim was to present a novel bite force-measuring device that could help reducing the costs.
    Materials And Methods
    This study presented the design, fabrication, and calibration method of a novel low-cost bite force-measuring device based on a force-sensitive resistor and application of strain gages. The FSR 402 was the selected sensor, which was suitable in size for placement in mouth, sterilizable for reuse, and contained biocompatible material.It could measure a large bite force of up to 90kgwith high repeatability.The device had a liquid crystal display (LCD) for immediate visualization of the results and a system for quick calibration of the device in office. To assess the accuracy of the device, some forces were applied to the sensor in nine values from11 to 80kg. The mean of measured force, absolute error, and error percentage were measured and recorded.
    Results
    The mean relative error was almost 2% within the range of 11-80kg. The lowest error percentage was 0.46% at the load of 52kg and the highest error percentage was 3.97% at the load of 28 kg.Error percentage was 2.51% in the lowest range (11kg) and 2.65% in the highest range (80kg).The relative error in different ranges did not follow a particular trend.
    Conclusions
    The bite force-measuring device is an economical and user-friendly appliance that can be simply used for routine practice in the office. The device shows good linearity and repeatability. It also has a calibration apparatus that can help maintaining the device accuracy.
    Keywords: Bite Force, Strain Gauge, Force Sensitive Resistor Sensor
  • Mohammad Motamedifar*, Ali Nozari, Elmira Azhdari Ghasrodashti Pages 484-488
    Statement of Problem: Indiscriminate use of antibacterial agents increases the antibiotic resistance, which consequently necessitates seeking alternatives such as herbal remedies.
    Objectives
    The aim of this study was to evaluate the antimicrobial effect of hydroalcoholic extract of Helichrysum leucocephalum (H.leucocephalum) on Streptococcus mutans (S. mutans) growth as a major cause of dental caries.
    Materials And Methods
    In this study, hydroalcoholic extract of H. leucocephalum was prepared. The antibacterial effects, minimal inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) of hydroalcoholic extract of H. leucocephalum and penicillin were assessed. Agar well diffusion method and micro broth dilution assay were used on bacterial suspension adjusted to a 0.5 McFarland standard (equivalent to 1.5×108 CFU/mL).Each test was repeated four times to minimize lab errors.
    Results
    In this study, the inhibitory zone of hydroalcoholic extract of H.leucocephalum in concentration of 100 mg/mL was 34±0.1 mm and for penicillin was 10 mm. The MIC and MBC of H.leucocephalum hydroalcoholic extract were 5.6±6.25, 21.6±6.25 mg/mL, respectively.
    Conclusions
    Hydroalcoholic extract of H. leucocephalum have antibacterial effect on S.mutans at a concentration of 12.5mg/mL, indicating possible application of this extract in prevention of dental caries; however, future researches are necessary.
    Keywords: Antimicrobial, Helichrysum leucocephalum, Streptococcus mutans