Showing 9 results for Mohammad Reza
S. Mir Mohammad Rezaee , A. Taghavi Nia ,
Volume 15, Issue 2 (8 2002)
Abstract
Recently. Minalux alloy, a base metal free from Be, has been presented on the market while no special soldering has been recommended for it. On the other hand, based on the manufacturer's claim, this alloy is similar to Verabond2. The aim of this study was to investigate the tensile strength of Minalux and Verabond2, soldered by Verasolder. Twelve standard dambble shape samples, with the length of 18 mm and the diameter of 3mm, were prepared from each alloy. Six samples of each alloy were divided into two pieces with carboradom disk. Soldering gap distance was 0.3mm, measured by a special jig and they were soldered by Verasolder alloy. Six other samples, of both Iranian and foreign unsoldered alloys were considered as control group. Then samples were examined under tensile force and their tensile strength was recorded. Two- way variance analysis showed that the tensile strength of Minalux alloy and Verabond2 were not statistically significant (Verasoler 686, Minalux 723), but after soldering, such difference became significant (Minalux 308, Verabond2 432). Verabond2 showed higher tensile strength after soldering.
A. Monzavi , S. Mir Mohammad Rezaei , H. Bajelan ,
Volume 15, Issue 2 (8 2002)
Abstract
Waxes have a lot of applications in dentistry. Such materials are of thermoplastic type that undergoes deformation in different temperatures. Two important properties of base plate waxes are flow and their coefficient of linear thermal expansion. Recently, different institutions, inside the country, produce dentistry waxes, while they have not been standardized. Consequently, consumers' dissatisfaction are observed. In this research, the two above- mentioned factors were compared between three kinds of Iranian waxes with Cavex that is foreign production, based on test number 24 of ADA. To measure the flow rate in the temperatures of 23, 37 and 45°c, Wilcoxon statistical analysis was used. The results showed that in 23°c, the flow rate of Cavex and Azardent waxes met ADA standards however, it was not true for two others types. In 37°c, the flow of none of the waxes was standardized and in 45°c their flow was acceptable, moreover, thermal expansion coefficient, for Cavex and Azardent types, was based on ADA standard.
Hadi Ghasemi, Mohammad Reza Khami,
Volume 25, Issue 1 (7 2012)
Abstract
Background and Aims: The present study aimed to evaluate the barriers to the production of scientific dental articles in dental schools in Iran based on the opinions of dental postgraduate students.
Materials and Methods: A self-administered questionnaire was distributed among postgraduate students of all Iranian dental schools in June 2010. The respondents rated their agreement with eight sentences about what hinder them from producing scientific dental articles based on a 5-grade Likert scale. The data were analyzed using Chi-square test.
Results: Totally, 270 filled questionnaires from 14 dental schools were received. Of all respondents, 53% were male, the mean age were 29.6 ± 3.8. About half of the respondents reported at least one published article. Less than half of the respondents reported producing an article from undergraduate thesis more women than men and more younger than older students (P<0.03). About two-third of the respondents rated absence of an English editing center, no financial incentives, no appropriate environment, and no competency for scientific writing as most prevalent barriers to the production of scientific dental articles.
Conclusion: To expand the share of Iran in the production of scientific dental documents, the potential of postgraduate dental students must be regarded and suitable condition for scientific writing must be provided. Specifically, based on the findings of the present study, provision of an English editing facility, establishing financial incentives, and providing the students with appropriate environment and efficient scientific writing education are of utmost importance.
Amir Aliramezani, Mohammad Hosein Salari, Mohammad Reza Pourmand, Zeinab Kadkhoda, Abbas Foroushani, Farzaneh Aminharati, Sedigheh Ghourchian, Zahra Pakbaz, Saeed Eshraghi,
Volume 25, Issue 3 (1 2012)
Abstract
Background and Aims: Periodontitis is one of the most common oral diseases with the various incidence rates in different populations. A number of bacteria are considered as the major etiologic agents of periodontitis. The aim of the present study was to determine the prevalence of periodontopathogen bacteria in patients using both PCR and culture techniques.
Materials and Methods: In this study, one-hundred patients (including 62 females and 38 males with an average age of 49±11.5 years) with adult periodontitis referred to periodontics department of School of Dentistry/Tehran University of Medical Sciences were investigated. The samples were taken and sent immediately to the laboratory for culture and molecular evaluation. The PCR was performed using specific primers and the statistical analysis of data was performed using SPSS statistic software and McNemar test.
Results: The results demonstrated that the total detection rate in culture method was 64%. The rate of Aggregatibacter actinomycetemcomitans (Aa) was 28% which was significantly higher than that of Porphyromonas gingivalis (Pg) (6%) and Prevotella intermedia (Pi) (3%). 27% of cases showed mixed bacterial growth. 65% of patients were positive using molecular method. The rate of Aa (30%) was significantly higher than that of Pg (7%) and Pi (5%). The mixed PCR positive rate containing of Aa, Pg and Pi was (23%).
Conclusion: In this study, it was found that most of the bacteria isolated using culture and molecular methods were Aa, Pg and Pi, respectively. Although the detection frequencies of both techniques were similar, the specificity, sensitivity and bacterial detection speed of the PCR technique is obviously higher. Therefore, the use of molecular techniques is strongly recommended. However, both techniques seem to be suitable for microbiological diagnostics.
Eshagh Ali Saberi, Fereydoon Sargolzaei Aval , Arab Mohammad Reza Mohammad Reza , Seddighe Ebrahimipour ,
Volume 26, Issue 3 (8-2013)
Abstract
Background and Aims: The purpose of this study was to evaluate the tissue responses to octacalcium phosphate (OCP) and calcium hydroxide (CH) used as direct pulp capping (DPC) materials in cat teeth.
Materials and Methods: 72 premolar teeth of 9 cats were selected and divided into 3 groups (Two experimental and one control group). After the cats had been anesthetized, the pulp were exposed and capped directly with OCP, CH or no capping material as control group. The cavities of all three groups were filled with Glass ionomer cement (GI). Histological evaluations were performed at two, four and eight weeks after pulp capping. After tissue preparation procedures, paraffin blocks were prepared. After preparation and staining of the sections, the relevant variables were measured by optical microscope. The results were analyzed using Mann-Whitney U and Chi-square tests ( α =0.05).
Results: Two weeks after pulp capping, all specimens in three groups showed mild to sever inflammation. The formation of hard tissue (dentinal bridge) at in the exposed areas of the experimental groups was more noticeable for calcium hydroxide than that of octacalcium phosphate group. These differences were statistically significant (P<0.001). At four weeks, hard tissues were observed in both groups which were more evident for the CH group and there were statistically significant difference between two experimental groups (p<0.003). At eight weeks, continuous hard tissues were observed in both groups and there were no statistically significant difference between them (P>0.05), but hard tissues continuity were better for in the OCP than that of the CH.
Conclusion: It seems that the formation of hard tissue in CH because of its porosities had a worse percentage in sealing of the pulp than the OCP .
Lelya Sadighpour, Sousan Mir Mohammad Rezaei, Hamid Jalali, Shadab Rashtak,
Volume 26, Issue 4 (1-2014)
Abstract
Background and Aims: Retention and stability of the post and core system is the key factor for success of final restoration . The aim of this study was to evaluate the microtensile bond strength of the different composite core materials and bonding systems to a fiber post.
Materials and Methods: To evaluate the bond strength of the composite resins to a fiber post ( DT light post) 60 posts were divided into six groups : group A: Heliomolar Flow + Seal Bond, group B: Heliomolar Flow + SE Bond , group C: Valux Plus + Seal Bond , group D: Valux Plus + SE Bond , group E: Corecem + Seal Bond, group F: Corecem + SE Bond. All samples were thermocycled for 5000 cycles (5-55 0C) and cut into four bars for the microtensile bond strength test. Failure modes were identified using a stereomicroscope. Data were analysed using One-way ANOVA and Tukey HSD post hoc test (P<0.05).
Results: The interaction between composite resin materials and bonding systems were positive. The conventional hybrid composite (Valux Plus) had significantly higher bond strength compared with the core specific flowable composite (Corecem) when Seal Bond was applied as bonding agent (P<0.05). However, when SE Bond was utilized hybrid composite demonstrated significantly lower bond strength than that of other two groups (P<0.05).
Conclusion: The performance of a particular composite is affected by the bonding system that is applied. A single composite resin may have different bond strength when combined with different bonding system.
Sara Ghadimi, Mohammad Reza Khami, Samaneh Razeghi,
Volume 28, Issue 1 (5-2015)
Abstract
Background and Aims: Despite significant decline in dental caries in recent decades, the disease remains a
public health problem especially in developing countries. In recent years combined application of laser and
fluoride has been introduced as a new caries-preventive measure. The purpose of the present study was to review
the literature on the preventive effect of combined application of laser and fluoride on the dental caries.
Materials and Methods: PubMed, Google Scholar and EMBASE databases were searched for articles published
from 1990 to November 30, 2013. Various combinations of the following keywords were used: Dental caries,
Laser, Fluoride, Fluoride therapy, Prevention and Enamel. The inclusion criteria included all levels of available
evidence. Articles published only in english language were evaluated, and unpublished data were not sought.
Results: Several studies evaluating the effect of laser alone or combined with topical fluoride to prevent dental
enamel demineralization were found. Studies assessing the combined effect were more frequently done on
permanent teeth and just a few studies were done on primary teeth. In total, most of the studies confirmed that
combined application of laser and topical fluoride has a remarkable effect in prevention of enamel
demineralization compared to application of each of them alone.
Conclusion: Laser irradiation combined with topical fluoride application seems to provide the best prevention
effect on the dental caries initiation and progression in enamel of permanent teeth. However, more experimental
and clinical studies are necessary to be done on the primary teeth in this area.
Mohammad Reza Khami, Hooman Keshavarz, Samaneh Razeghi,
Volume 30, Issue 1 (6-2017)
Abstract
Background and Aims: Opinion of students regarding the content, structure and quality of their training is a fundamental part of holistic evaluation of curriculum, and serves as an important information resource in policy making. In the present study, we aimed to contribute to the development, assessment and evaluation of the new national dental curriculum through evaluation of last-year dental students’ opinions regarding undergraduate dental curriculum.
Materials and Methods: This cross sectional questionnaire survey was done in 2010-2011 academic year. The target population was last-year dental students in 15 Iranian state dental schools. In these schools, all last-year dental students were invited to participate in the study. The chi-square test served for statistical analyses.
Results: In total, 432 students (68.4% female) participated in the study. Of the respondents, 72.4% (60.7% of male and 77.6% of female, P=0.001) believed that their undergraduate dental training had been completely inadequate or inadequate. Only about one third of students believed that educational methods during their undergraduate dental training had been appropriate or completely appropriate.
Conclusion: In general, it seems that undergraduate dental training from students’ view point has not been appropriate in terms of both content and method. The results show the necessity of revision of national undergraduate dental curriculum.
Sadighe Mozafar, Mandana Sattari, Somayeh Kameli, Zohre Sadat Hosseinipour, Mohammad Reza Sedighian Rad,
Volume 34, Issue 0 (5-2021)
Abstract
Background and Aims: Survival of periodontal ligament (PDL) cells after avulsion is an important factor in treatment prognosis. Grapefruit Seed Extract (GSE) can be a proper environment for preserving periodontal ligament cells. The objective of this study was to analyze the effect of different concentrations of GSE on the proliferation of fibroblast PDL cells.
Materials and Methods: In this study, the undifferentiated PDL fibroblasts were obtained from two human premolars teeth and cultured in Dulbecco’s modified Eagle’s medium (DMEM). The cultured cells were exposed to different concentrations of GSE. The positive and negative control groups were cultured in fetal bovine serum (FBS) 10% and in a medium without FBS 10%, respectively. The plates were incubated for 1, 6, 12, 24, and 48 hrs. The PDL cell viability was assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Statistical analysis of data was accomplished using repeated measure ANOVA with Post HOC Tukey, P<0.05 was considered statistically significant.
Results: We found out that among different concentrations of GSE, 1:128 had the most impact on undifferentiated PDL fibroblasts. Although, the cell vitality was higher in the twelfth hour, 1:128 GSE and in the forty-eighth hour, 1:1024 GSE than the positive control group but they were not statistically significant (P>0.05). Furthermore, all the samples were similar to the positive control group in three of the five timeperiods (P>0.05).
Conclusion: GSE was more effective in fewer concentration and longer periods and it had no toxic effect on PDL cells. Therefore, GSE can be considred as a promoting medium in PDL regeneration of avulsed permanent teeth in the future.
