Showing 12 results for Jafarzadeh
M. Ghavam , T. Jafarzadeh, P. Alizadeh Oskouei ,
Volume 14, Issue 3 (9 2001)
Abstract
Polymerization shrinkage of light cure composite resins causes many complications in conservative and esthetic restorations. The objective of this in-vitro study was to evaluate the polymerization shrinkage, degree of conversion and the amount of filler in IDM and tetric ceram composites. Ten disk shaped, uncured specimens (8mm×1.547mm) of each composite were placed on glass slide in the center of the metal attached to it. Then specimens were light cured for 60s from underneath. After 30 minutes, the thickness of specimens, using a micrometer and the percent of the polymerization shrinkage of each sample were measured. Statistical analysis was carried out by t-test (P<0.05). Also the degree of conversion of specimens was evaluated with FTIR and the mineral filler content was measured by burning in electric oven. Polymerization shrinkage in IDM and tetric ceram was not significantly different. Degree of conversion and mineral filler content in tetric ceram was greater than that of IDM.
It is assumed that the low degree of conversion in IDM is due to its chemical composition and filler content. Also, the similarity in linear polymerization shrinkage between IDM and tetric ceram may be caused by the low degree of conversion in IDM.
T. Jafarzadeh , M. erfan , Dc. Watts , A. Cash ,
Volume 15, Issue 2 (8 2002)
Abstract
Dentine bonding systems are usually unfilled, and so their shrinkage may be significant. High shrinkage may cause internal stress at the interface between resin-composite restoration and the dentine substrate. Failure of the adhesive interface may be observed due to the interna! stress. The aims of this study were:A) To obtain a suitable method for measuring the kinetics of polymerisation shrinkage in unfilled resm at different thicknesses, particularly for thin films.B) Consideraing the effect of thickness on shrinkage.Scotchbond Multipurpose (3M) adhesive bond resin was used. To overcome the particular challenges presented by thin films, a filled-ring measurement procedure was used. Also, a non-contact laser analogue displacement sensor system was developed and applied to measure polymerisation shrinkage. Regression analysis was performed on a complete data set. Non-linear regression analysis established a logarithmic relationship between polymerisation shrinkage and layer thickness. The method applied in this study was found to be sensitive and accurate procedure for determining photo-polymerisation shrinkage of thin films. Polymerisation shrinkage increased with logarithmic of the adhesive thickness.
Ts. Jafarzadeh Kashi, M. Erfan ,
Volume 18, Issue 1 (30 2005)
Abstract
Statement of Problem: The quantity of remaining unreacted double bonds may be a significant factor pertaining to the mechanical, physical and chemical properties of restorative resins. Insufficient polymerisation within the hybrid layer may cause significant differences in the quality of this layer, and act as a reservoir for monomer release thus increasing cytotoxic potential.
Purpose: The aim of this study was to measure the degree of conversion of three generations of 3M dentin bonding agents and an experimental dentin bonding agent
Materials and Methods: The quantity was determined from the transmission IR-spectrum of the materials before and after polymerization. ScotchBond MP plus adhesive, SingleBond, Prompt L-Pop, and an experimental dentin bonding were used to measure degree of conversion. Six repetitions of each bonding were investigated. Time of light curing was 120s. Kruskal-Wallis and Mann-whitney test were used to compare groups with P<0.05 as the limit of significance.
Results: The results showed a significant difference between groups (P<0.01). A trend of increasing in Singlebond conversion obtained in comparison with ScotchBond MP plus adhesive, Prompt L-Pop and experimental dentin bonding. The degree of conversion was not statistically significant among the other dentin bondings. No significant difference was found between conversion of the experimental dentin bonding and ScotchBond MP plus adhesive (P=1.00) with P<0.05 as the limit of significance.
Conclusion: Dentin bonding technology continues to evolve toward simpler systems. However, Prompt L-Pop as a self-etching adhesive does not show the trend of increasing the degree of conversion. However, the performance of these simpler systems must be further investigated.
A. Monzavi , S. Zarati , T. Jafarzadeh , Mh. Amini ,
Volume 19, Issue 3 (4 2006)
Abstract
Background and Aim: Use of provisional restorations is one of the important phases in the treatment of patients who need fixed prosthesis. Some physical properties are required for these materials. The purpose of this study was the comparison of some physical properties of 4 kinds of resins: Trim, Tempron, Duralay (Aria Dent) and Acropars TRII.
Materials and Methods: In this experimental study, transverse-strength (TS), setting time (ST), polymerization shrinkage (PS) and temperature rise (TR) during polymerization were tested. In transverse strength test, 5 samples of each resin were made. TS testing was done with an Instron testing machine. ST testing (5 samples in each group) was done with Gilmore needle. In PS test, 11 cylindric samples were prepared from each resin and the shrinkage was examined with digital micrometer (up to 24 hours). In TR test, after mixing the powder and liquid of resins (8 samples in each group), the temperature rise was recorded with 10 seconds interval (up to 15 minutes). Data were analyzed with one-way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance.
Results: In TS test, all samples of Trim were bent and no fracture was observed, while Tempron and Duralay showed no significant difference. Both Tempron and Duralay revealed high significant difference with Acropars TRII (P <0.01). In ST test, the difference between groups was significant (P<0.01). The lowest ST was observed in Acropars TRII (7 min), and the highest in Tempron (9.53 min). In PS test, significant difference was observed between Trim and Acropars TRII (P<0.01). PS was completed after 120 min in Tempron and Trim groups. However, PS continued to increase in other groups. In TR test, the difference between groups was significant (P<0.05). Duralay showed the highest TR and the lowest was seen in Trim.
Conclusion: In this study, Trim showed better properties than other studied groups. Acropars TRII had the lowest strength. The highest temperature rise was recorded for Duralay and Tempron, respectively.
Mh. Zarrabi, M. Bidar , H. Jafarzadeh ,
Volume 20, Issue 1 (4 2007)
Abstract
Background and Aim: Mechanical preparation of canal is one of the most important stages in root canal therapy. Various kinds of hand or rotary techniques are used for mechanical preparation of canal and each of them has advantages and disadvantages. During canal preparation, extrusion of debris from the apical foramen can result in periapical inflammation and increased pain and edema. The aim of this study was to compare hand instrumentation technique with three rotary systems (Profile, Race, Flex Master) regarding the amount of extruded debris from apical foramen during canal preparation.
Materials and Methods: In this experimental in vitro study, one hundred human extracted single rooted mandibular premolars with curvature between 0-10 degrees were selected and divided into four groups of 25 teeth each. All teeth were shortened to 15 mm length by cutting the crown. Group H was prepared by hand step back technique, group P by Profile system, group R by Race system and group F by Flex Master system. For debris collection, vials containing distilled water were used which were weighed before preparation. After the end of canal preparation, vials were completely dried and weighed again. The difference between weights of vials in two stages was the weight of debris extruded from apical foramen. The groups were compared by One-way ANOVA with p<0.05 as the level of significance.
Results: Group H had the highest mean weight of debris which showed significant difference with all three rotary groups (P<0.001). The lowest mean weight of debris was observed in group R (Race) which was significantly different from group F (Flex Master) but not significantly different from group P (Profile).
Conclusion: Based on the results of this study, race rotary system caused less debris extrusion from apical foramen compared to hand step back technique and Flex Master rotary system.
T. Jafarzadeh Kashi, M. Erfan, A. Nezadi Niasar,
Volume 22, Issue 3 (1 2009)
Abstract
Background and Aim: Evaluation of shear bond strength and microleakage of bonding agents is important as these properties play main roles in adhesion of composite to dental tissues. Microleakage results in bacterial penetration into dentin tubules and enamel surfaces and causes sensitivity and recurrent caries followed by destruction of composite filling. Insufficient shear bond strength results in early failure of filling in low masticatory forces. The main goal of this study was to compare the microleakage and shear bond strength of an experimental adhesive and Scotchbond multi-purpose (MP) adhesive system.
Materials and Methods: In this experimental study, sixty extracted caries free human molar teeth were randomly assigned into 4 groups of 15 each for shear bond strength. Variables were bonding agents, enamel and dentin. Twenty teeth assigned into 2 groups of 10 each were used for valuation of the microleakage. Microleakage and shear bond strength were performed according to ISO TR 11405. All data were analyzed with parametric and non-parametric tests according to their normality distribution. Also, Weibull distribution performed on data.
Results: Data obtained from both microleakage and shear bond strength tests showed no significant difference between the experimental bonding and Scotchbond MP bonding (P>0.05). Furthermore, there was no significant difference between the microleakage of occlusal and gingival parts of both bondings (P>0.05).
Conclusion: Experimental adhesive bonding showed acceptable results regarding microleakage and shear bond strength. It may be concluded that the experimental dentin bonding had a comparable performance quality with that of commercial system.
Tahereh Sadat Jafarzadeh Kashi, Mohammad Erfan, Akbar Fazel Najafabadi, Seied Mostafa Fatemi, Marjan Behroozibakhsh, Haleh Hali, Hosein Bagheri Gorgani,
Volume 25, Issue 2 (9 2012)
Abstract
Background and Aims: The aim of this study was to measure the degree of conversion (DC) of three types of composite resins (micro-hybrid, nano-hybrid and Ormocer) with different light curing units (LED LCU and QTH LCU) in two depths.
Materials and Methods: Three commercially available dental resin composites were used in this study: (Tetric Ceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Tetric Evoceram, Ivoclar Vivadent, Liechtenstein-A2 shade), (Ceram X, Dentsply, Germany-M2 shade). Specimens were divided into two groups, 5 specimens were photo-activated by QTH unit (Coltolux 75-Colten) and the other five specimens were cured by LED (Demi-Kerr). Then each specimen was sectioned at the top surface and at 2-mm depth. The DC was measured by FT-IR
(Bruker-tensor 27). The data were analyzed by 3-way ANOVA test.
Results: There was significant difference between tested composite resins (P<0.001). The results of top surfaces were significantly different from those observed at 2-mm depth (P<0.001). The type of curing unit affected the polymerization of Ceram X resin composite.
Conclusion: This study showed a significant difference in the degree of conversion in different thicknesses within three groups of resin composites.
Mehdi Jafarzadeh Samani, Maryam Hajiahmadi, Samira Yousefi, Elham Sadat Binande,
Volume 26, Issue 2 (5-2013)
Abstract
Background and Aims: Successful pediatric dentistry depends not only on the dentist's technical skills, but also on his ability to acquire and maintain a child's cooperation. The correction of dentist’ action in this area affects the view of parents and increases the quality of dental services. The objective of this study was to evaluate the attitudes of general dentists toward methods of controlling pediatrics’ behavior in Isfahan.
Materials and Methods: This study is descriptive, analytic, and cross-sectional. For this research, 100 general dentists of Isfahan city were selected with simple random sampling technique and were asked to complete the questionnaire which was included four different management techniques. The data were analyzed with t-test, P earson’s correlation , ANOVA and Kruskal-Wallis.
Results: The methods accepted by dentists were Tell-Show-Do (4.0 ± 0.5), Voice control (3.5 ± 0.4), active restraint (3.0 ± 0.5) and Hand-Over-Mouth (2.9 ± 0.5) respectively. The mean score of female dentists’ attitudes was more toward the method of active restraint and less toward Hand-Over-Mouth technique. Also the average score of middle aged dentists’ attitudes toward Voice Control method was less than young dentists and toward Hand-Over-Mouth was higher. The general dentists with more number of pediatric patients had less consent on the method of Hand-Over-Mouth (P=0.004) and active restraint (P=0.034).
Conclusion: There were significant correlation between attitude of general dentists toward behavior management techniques with age, gender, clinical experience and the number of pediatric patients. General dentists have fewer tendencies to aggressive behavior management techniques.
Mehdi Jafarzadeh, Maryam Haji Ahmadi, Hajar Esmaielian, Hadi Moshkel Gosha,
Volume 27, Issue 3 (9-2014)
Abstract
Background and Aims: Successful pediatric dentistry depends on the dentist's technical skills, as well as his/her ability to acquire and maintain a child's cooperation. The correction of dentist’ performance in this area affects the view of parents and increases the quality of dental services. The aim of this study was to evaluate the attitudes of general dentists toward behavior guidance techniques in Isfahan.
Materials and Methods: In this descriptive- analytic cross-sectional study, 100 general dentists of Isfahan city were selected with simple random sampling technique. They were asked to complete the questionnaire inquiring their attitude toward four different behavioral management techniques . An appropriate question about each of the methods was proposed by the authors, along with demographic characteristics including: gender, age, university, year of graduation, work experience, the mean number of pediatric patients referred in one month was provided in the form of a questionnaire. To evaluate the attitude of dentists to the questionnaire, the score from 1 to 5 was given to each item and the total score was considered. Higher score indicated more positive attitude of dentist. Data were analyzed using T-test, Pearsons correlation and one-way ANOVA (P<0.05).
Results: The mean scores for dental behavioral management techniques were positive reinforcement (4.2±2.7), general anesthesia (3.5±4.4), N2O sedation (3.4±4.4) and pharmacologic sedation (3.2±2.7), respectively. There were no significant differences between the mean score of dentist attitude and age, gender, clinical experience and the number of pediatric patient (P>0.05).
Conclusion: General dentists’ attitudes towards different behavior management techniques were associated with age, gender, clinical experience and the number of pediatric patient. General dentists’ tend was more towards non-drug behavior control methods such as positive reinforcement.
Reza Masaeli, Tahereh Sadat Jafarzadeh Kashi, Farhad Shafiei,
Volume 28, Issue 3 (10-2015)
Abstract
Poly (lactic-co-glycolic acid) is a biodegradable polymer which has used in a different fields of medical applications. As PLGA is approved by FDA(food and drug administration) the range of this usage is increasing in comparison to the past. Particularly, PLGA are also developed for the dental field in the form of scaffolds, films, membranes, microparticles, or nanoparticles. PLGA scaffolds have been used to regenerate damaged tissues together with stem cell-based therapy. There is solid evidence thatthe development of PLGA microparticles and nanoparticles may be beneficial to a wide range of dental fields such as endodontic therapy, dental caries, dental surgery, dental implants, or periodontology. The aim of the current paper was to review the recent advances in PLGA materials and their potential uses in Dentistry via exploring related literature during 2004 till 2016 in Science Direct and PubMed.
Mehrsima Ghavami-Lahiji, Marjan Behroozibakhsh, Tahere Sadat Jafarzadeh Kashi,
Volume 30, Issue 4 (1-2018)
Abstract
FTIR spectroscopic imaging is a chemical imaging method that can be employed to a broad range of applications. This powerful technique is suitable for determining the functional groups and chemical structures of the samples. The advantage of infra-red spectroscopy is that it can be used for various modes of physical samples. The aim of the current paper was to review the recent advances and the potential uses of Fourier Transform Infra-red Spectroscopy in dentistry via exploring related literature during 1960 till 2017 in Science Direct and PubMed databases. One of the most popular applications of infrared spectroscopy is to calculate the degree of conversion in the resin based dental materials. It has also been used to investigate the chemical structure of the teeth and bones, synthesis calcium phosphate, the diagnosis of microorganisms, and pathological conditions. In this paper, we mentioned the principles of this technique and recommend this method as a simple and fast way to determine the structure of the materials and their alteration.
Elnaz Shafiee, Amin Nourizadeh, Parisa Jafarzadeh Maleki,
Volume 38, Issue 0 (4-2025)
Abstract
Background and Aims: Achieving reliable tools for accurate shade matching of ceramic samples is of great importance in restorative and aesthetic dentistry. This study aimed to evaluate the accuracy of the Trios5 intraoral scanner in determining the shade of ceramic samples using the Vita Classical Shade Guide (VC).
Materials and Methods: This in-vitro study involved scanning each ceramic sample 15 times by two independent observers using the Trios5 intraoral scanner. The detected shade of each sample was compared with the reference shades of the Vita Classical Shade Guide (VC) and the compatibility of the scanner’s results with the reference shades was assessed. The data were analyzed using SPSS24 software and Pearson correlation and paired t-tests and kappa coefficient at a significance level of 0.05.
Results: The highest accuracy of shade detection in both observers was found for shades A2, A3, A3.5, A4, B1, and C4, each with 100% accuracy. The lowest accuracy for both observers was noted for shade A1, with 0% accuracy. The mean overall accuracy for the first and second observers was 64.99% and 63.75%, respectively, with a total overall accuracy of 64.37%. A statistically significant interobserver agreement was observed (P≤0.005).for all shades except B2 (P=0.299).
Conclusion: The Trios5 intraoral scanner can be considered a useful adjunct tool for ceramic shade determination. However, for clinical applications, it is recommended to use it in conjunction with reference tools and complementary methods such as spectrophotometry or visual assessment by experienced clinicians.
