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Showing 3 results for Methacrylate
Effects of leached components from a hybrid resin composite on the reproductive system of male mice
Masoomeh Hasani Tabatabaie, Ayob Pahlavan, Esmaiel Yasini, Mansore Mirzaie, Sakineh Arami, Hamid Kermanshah, Hamidreza Sadeghipour Roudsari, Seyed Hossein Bassir, Taher Akbari Saeed, Hamed Hasani,
Volume 25, Issue 3 (7-2012)
Abstract

Background and Aims: There is concern that leached components from dental composites may cause adverse changes in the reproductive health. This study aimed to assess the effects of leached components from a hybrid resin composite on the reproductive system of male mice.
Materials and Methods: In the present animal study, twenty adult Syrian male mice were divided into two groups of 10 mice each. In the test group, components which leached from samples made from Filtek Z250 resin composite into 75% ethanol were daily administered to the mice for 28 days. In the control group, the procedure was repeated in the same way as the test group but without placing composite samples in the solution. Then, the body weight, weights of paired testes, Gonado Somatic Index, sperm viability, sperm motility, epididymal sperm reserve and daily sperm production were recorded. Four male mice in each group were mated with untreated female mice for 10 days. After that, the number of pregnant females and number of infants were recorded. The data were analyzed using repeated measures ANOVA, Chi-square test and t-test.
Results: There was a significant reduction in the sperm viability and sperm motility of male mice in the test group compared to the control group (P=0.001). There was no any significant differences in other parameters between two groups (P>0.05).
Conclusion: This study showed that the leached components from resin composites cannot cause infertility but they could potentially cause some adverse effects on the reproductive system of male mice.


Comparison of Polymerization Shrinkage in Methacrylate and Silorane-Based Composites Cured by different LEDs
Ayob Pahlavan, Masumeh Hasani Tabatabaei, Sakineh Arami, Mohammad Ataie, Sara Valizadeh,
Volume 26, Issue 1 (3-2013)
Abstract

Background and Aims: Polymerization shrinkage in Methacrylate-based composite is one of the most important factors in composite restorations failure. Silorane-based composite is introduced to compensate this drawback and claimed to have low shrinkage. The aim of this study was to evaluate the polymerization shrinkage of these two composites.

Materials and Methods: In this experimental study, 5 disk shape samples for each resin composites were placed in the centre of metallic ring bonded to microscopic glass slab. Top surface of ring was covered by a glass cover slip. Glass slab and sample were placed on a special LVDT holder in order to light cure from bottom surface and to measure the polymerization shrinkage. In this study, Deflecting Disk method and LVDT (linear variable differential transducer) was used for dimensional change measurement of resin composites. In this study, two LED curing units were used for composite polymerization.

Results: The mean of polymerization shrinkage in Z250 cured with LED and High Power LED was 11.15±0.08µm and 11.51±0.17µm, respectively (P=0.094), and in P90 cured with LED and High Power LED was 1.08±0.06µm and 1.16±0.12µm, respectively (P=0.019).

Conclusion: Silorane-based composite (P90) showed significantly less polymerization shrinkage than that of methacrylate-based composite (Z250). For the two types of composite, there was no significant difference between the two curing units in polymerization shrinkage.


The effect of SiO2 nano-filler addition into heat-cured poly methyl methacrylate on three-point flexural strength
Sajjad Pezeshki, Saharnaz Hassanzadeh Kourandeh,
Volume 33, Issue 4 (1-2021)
Abstract
Background and Aims: Poly methyl methacrylate (PMMA) is still the most commonly used material in prosthetic dentistry. However, there are problems with the mechanical properties of this type of material including low flexural strength. Addition of nanoparticles into the polymer is one way to improve the mechanical properties of acrylic resin. In the present study, the effect of silicon dioxide (SiO2) nanoparticles addition into the heat-cured acrylic resin in different concentrations was investigated. Because of the controversy had been observed in previous articles, the aim of this study was to investigate the mechanical properties of PMMA/SiO2 nanoparticle obtained from different percentages of SiO2.
Materials and Methods: In this in-vitro study, acrylic resin specimens containing 0, 1, 3 and 5% silicon dioxide (SiO2) were prepared. The specimens were placed inside the gypsum molds and placed under pressure for three times. The mold cured in boiling water for 30 min. A trimmer was used to remove the additives. Sandpapers with 180, 320 and 600 grains of silicon-carbide were used for final finishing and polishing. Finally, the flexural strengths were measured using a universal testing machine. Data were finally analyzed by ANOVA and Tukey tests at a significant level of 5% using SPSS software.
Results: The mean flexural strengths and standard deviations of control group, 1% filler, 3% filler, and 5% filler, were 57.24±8.30, 69.98±7.26, 60.16±9.18, and 61.59±9.28 MPa, respectively. After comparing significant values between each group with the control group, a significant difference was observed between the control and 1% filler group (P=0.021). However, no significant difference was observed between 3 and 5% fillers with the control group or each other. The significant differences (P-value) between 3% filler and control group were 0.892 and between 5% filler and control group was 0.975.
Conclusion: The results of the present study showed that the use of low percentage of silicone dioxide (SiO2) nanofiller could improve the flexural strength of poly methyl methacrylate acrylic resin.

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