Mahmoud Bahari - Academia.edu (original) (raw)
Papers by Mahmoud Bahari
The journal of contemporary dental practice, 2012
Aim: The aim of the present study was to evaluate the effect of three methods of composite fiber ... more Aim: The aim of the present study was to evaluate the effect of three methods of composite fiber placement along with siloranebased composite resin on cuspal deflection and fracture strength of root-filled maxillary premolars. Materials and methods: Mesio-occluso-distal cavities were prepared in 60 extracted premolars subsequent to endodontic treatment. The remaining thickness of buccal and lingual walls at height of contour was 2.5 ± 0.2 mm and the gingival cavosurface margin was 1.5 mm coronal to cementoenamel junction. Subsequent to measurement of primary intercuspal distances, the teeth were randomly divided into four groups. In group 1, the cavities were only filled with Filtek Silorane composite resin. In the other three groups, preimpregnated glass fibers were placed at gingival, middle and occlusal thirds respectively, and the cavities were restored similar to the group 1. Cuspal deflection was recorded in micrometer using a stereomicroscope. Fracture strength of the samples was measured in Newton subsequent to thermocycling. Data was analyzed using Kruskal-Wallis, Mann-Whitney U, one-way ANOVA and post-hoc Tukey tests at a significance level of p < 0.05. Results: The highest cuspal deflection was recorded in the group 1, and the difference between group 1 and other groups was significant (p < 0.001). Fracture resistance in group 4 was significantly higher than that in other groups (p < 0.001). Conclusion: In restoring root-filled premolars with siloranebased composite resins, cuspal deflection decreased with the use of preimpregnated glass fibers. Clinical significance: Using preimpregnated glass fibers along with silorane-based composite resin may lead to better results in cuspal deflection and fracture resistance of endodonticallytreated maxillary premolars.
PubMed, 2014
Background and aims. The aim was to evaluate the effect of casein phosphopeptide-amorphous calciu... more Background and aims. The aim was to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on microtensile bond strength (μTBS) to carious affected dentin (CAD) using etch-and-rinse and self-etch adhesive systems. Materials and methods. The occlusal surface of 32 human molars with moderate occlusal caries was removed. Infected dentin was removed until reaching CAD and the teeth were randomly divided into two groups based on the Single Bond (SB) and Clearfil SE Bond (CSE) adhesive systems. Before composite resin bonding, each group was subdivided into three subgroups of ND, CAD and CPP-ACP-treated CAD (CAD-CPP) based on the dentin substrate. After dissecting samples to l-mm-thick cross-sections (each subgroup: n = 13), μTBS was measured at a strain rate of 0.5 mm/min. Data was analyzed using two-way ANOVA, independent samples t-test and post-hoc Tukey tests (α=0.05). Results. Bond strength of both adhesive systems to ND was significantly higher than that to CAD (P <0.001) and CAD/CPP (P < 0.001). There were no significant differences between the μTBS of SB to CAD and CAD-CPP (P > 0.05).μTBS of CSE to CAD-CPP was higher than that to CAD; however, the difference was not significant (P > 0.05). Significant differences were found between SB and CSE systems only with CAD substrate (P < 0.001). Conclusion. Regardless of the adhesive system used, surface treatment of CAD with CPP-ACP did not have a significant effect on bond strength. However, bond strength to CAD was higher with SB rather than with CSE.
Operative Dentistry, Sep 1, 2012
In order to avoid the negative effect of contamination of composite resins with powdered latex gl... more In order to avoid the negative effect of contamination of composite resins with powdered latex gloves on the bond strength of two-step self-etching adhesive systems, the use of unpowdered latex gloves is recommended with these adhesive systems.
Journal of Dental Research, Dental Clinics, Dental Prospects
Background. Contamination of dentin surface is one of the common problems in restorative dentistr... more Background. Contamination of dentin surface is one of the common problems in restorative dentistry. The aim was to investigate the effects of different surface contaminators on the dentin shear bond strength (SBS) of universal adhesive system (UAS) applied in etch-and-rinse (ER) and self-etch (SE) strategies. Methods. One hundred forty-four maxillary anterior sound human teeth were divided into six groups based on the types of surface contaminators: no surface contaminator (control) and experimental groups contaminated with blood, saliva, aluminium chloride (ALC), ferric sulphate (FS), and caries disclosing agent (CDA). Then, each group was further subdivided into two, based on the application strategy of UAS (ER and SE). After applying the adhesive according to the manufacturer’s instructions, and bonding cylindrical composite samples, the SBS was measured. The data were analysed using two-way ANOVA, Tukey’s HSD test and t test (P<0.05). Results. The SBS in all contaminated grou...
Journal of Clinical and Experimental Dentistry
Background: Bond strength of indirect restorations is a very important issue that should be given... more Background: Bond strength of indirect restorations is a very important issue that should be given special attention. Immediate dentin sealing (IDS) technique has been suggested in recent years. The aim of the present study was to investigate the effect of different strategies of universal adhesive application for immediate and delayed dentin sealing (DDS) on the microtensile bond strength (μTBS) of self-adhesive resin cement with and without aging. Material and Methods: In this experimental study, 24 healthy human third molars were selected. After exposing the occlusal dentin, the teeth were randomly divided into two groups of 12 based on the All-Bond Universal adhesive application strategy (etch-and-rinse or self-etch). Each group was further subdivided into two (n=6) based on IDS or DDS technique. Then composite blocks were cemented on the occlusal surface with self-adhesive resin cement. After cutting the samples into 1 mm 2 cross-sections, half of the samples of each subgroup were subjected to µTBS test after one week, and the other half were tested under μTBS after 10,000 thermal cycles. Data were analyzed using three-way ANOVA (P<0.05). Results: μTBS was significantly affected by all three factors of bond strategy, sealing technique and aging. There was also a significant interaction between the three factors. Conclusions: Immediate dentin sealing improved μTBS. The etch-and-rinse strategy resulted in higher μTBS, while aging led to a decrease in μTBS.
Journal of Dental Research, Dental Clinics, Dental Prospects
Background. Considering the increased use of preheating and novel resin-based materials to restor... more Background. Considering the increased use of preheating and novel resin-based materials to restore teeth, the present study investigated the impact of preheating on the flexural strength of a giomer and compared it with a nanohybrid composite resin. Methods. Two restorative materials (Beautifil II giomer and Alpha III nanohybrid composite resin) were used. Thirty rod-shaped samples (adding up to 60 samples) were prepared from the materials above and divided into two subgroups: with and without preheating (n=15). Before sample preparation, the giomer and nanohybrid composite resin tubes were preheated at 68ºC for 15 minutes in the preheating subgroups. In the subgroups without preheating, the tubes were kept in a room at 25ºC. Then the flexural strength was compared between the two groups with two-way ANOVA at a significance level of P<0.05. Results. The results showed significantly higher flexural strength in the preheated subgroups than in the non-preheated subgroups (P<0.001...
Dental Research Journal
Background: Cention N has been introduced as an alternative material for amalgam. The purpose was... more Background: Cention N has been introduced as an alternative material for amalgam. The purpose was to investigate the flexural strength and microhardness of this material in self-cure and dual-cure modes before and after thermocycling. Materials and Methods: In this experimental study, 40 samples of Cention N were prepared in order to determine and compare the microhardness. Half of the samples were set by self-cure method and the other half with dual-cure method. The Vickers microhardness test was performed once after 24 h and again after 10000 thermocyclings. Three-point flexural test was used to determine and compare the flexural strength of 52 rod-shaped samples. Half of the samples were set by self-cure method and the other half with dual-cure method. Among 26 samples in each group, 13 samples were randomly selected and three-point flexural test was performed after 24 h and for another 13 samples after 10,000 thermocyclings. Data were analyzed using two-way ANOVA and paired samples t-test (P < 0.05). Results: There was a statistically significant difference between the mean of microhardness values in two curing methods (P < 0.001) and in two storage conditions (P < 0.001). The mean of dual-cure microhardness (100.99 ± 7.22) was higher than that of self-cure (64.61 ± 12.51) and the mean value associated with pre-thermocycling (89.75 ± 15.84) was higher than that of the post-thermocycling (76.44 ± 23.56). There was no statistically significant difference between the mean flexural strength in the two curing methods (self-cure [72.85 ± 16.26], dual cure [79.87 ± 23.07]; [P > 0.05]). However, the mean flexural strength without thermocycling (85.98 ± 21.74) was higher than that of the thermocycled group (64.24 ± 6.40) (P < 0.001). Conclusion: The microhardness of Cention N in dual-cure mode was higher than that of self-cure mode, but the flexural strength of dual-cure was not significantly different from that of self-cure. Thermocycling had a significant effect on the microhardness and flexural strength.
پانزدهمین کنگره انجمن متخصصین دندانپزشکی ترمیمی ایران, 2015
دوازدهمین کنگره بین المللی انجمن متخصصین دندانپزشکی ترمیمی ایران, 2012
پانزدهمین کنگره انجمن متخصصین دندانپزشکی ترمیمی ایران., 2015
پانزدهمین کنگره انجمن متخصصین دندانپزشکی ترمیمی ایران, 2015
Journal of dental research, dental clinics, dental prospects, 2021
Background. Prevention of dentinal crack formation is of utmost importance in endodontic treatmen... more Background. Prevention of dentinal crack formation is of utmost importance in endodontic treatment. This study aimed to evaluate the effect of RaCe, ProTaper, and V-Taper rotary systems on dentinal crack formation in three root regions during endodontic treatment. Methods. Seventy human mandibular first molars were selected randomly, and their distal roots were used. Ten samples were assigned to the control group, and sixty samples were assigned to three groups (n=20). Each group was prepared with RaCe, ProTaper, or V-Taper rotary files according to the manufacturers' instructions. A stereomicroscope was used to view cracks at ×40 magnification. Friedman's, chi-squared, and Kruskal-Wallis tests were used for statistical analysis of data (P < 0.05). Results. A comparison of the three rotary systems did not reveal any significant differences in the number of cracks between the three root thirds evaluated (P > 0.05). A comparison of the number of cracks in the coronal, mi...
Maedica, 2020
Objectives: The present study aimed to evaluate the effect of curing time and bleaching agents on... more Objectives: The present study aimed to evaluate the effect of curing time and bleaching agents on microhybrid composite resin surface microhardness. Material and method: A total of 180 microhybrid composite resin disks were divided into two groups in terms of curing time: 40 s, 60 s. Then, each group was divided into three subgroups: control (distilled water), home bleaching (15% carbamide peroxide) and office bleaching (40% hydrogen peroxide). Surface microhardness of the samples was determined by using Vickers hardness test both at baseline and after the completion of the tests. Two-way ANOVA and Tukey HSD tests were used to analyze and compare microhardness changes between groups. Statistical significance was defined at P<0.05. Results: Based on the two-way ANOVA, curing time, bleaching method, and cumulative effect of these two variables significantly affected composite resin microhardness (P<0.001). Tukey HSD tests showed that microhardness had significantly decreased in ...
iranian endodontic journal, 2019
Introduction: Relining fiber posts using composite resins helps the posts adapt to the anatomical... more Introduction: Relining fiber posts using composite resins helps the posts adapt to the anatomical space of the root canals. The aim of this study was to evaluate the effect of composite resin type on the push-out bond strength of anatomical fiber posts to intra canal dentin. Methods and Materials: Forty-eight bovine upper incisors were prepared for post space after root canal therapy and randomly divided in to six groups. Five different types of composite resin (GrandioSO, GrandioSO Heavy Flow, X-tra Fil, X-tra base and everX Posterior) were used for relining the prepared fiber posts. In the control group, the prepared post was cemented into the post space without relining. Cervical, middle and apical cross-sections were achieved from each root and push-out test was conducted at a crosshead speed of 0.5 mm/min. One sample from each group was scanned using a micro-CT scanner which provided views from the apical, middle and coronal thirds. Data were analyzed using Kolmogorov-Smirnov t...
Journal of Clinical and Experimental Dentistry, 2020
Background: The present study was aimed to evaluate the effect of pre-heating of bulk-fill resin ... more Background: The present study was aimed to evaluate the effect of pre-heating of bulk-fill resin composites on monomer elution from them. Material and Methods: Three different types of resin composites were used including Tetric N-Ceram Bulk Fill, X-tra Fill and X-tra Base. 10 cylindrical samples were prepared from each resin composites. Before light curing, 5 samples were pre-heated until reaching 68˚C, then 5 other samples were polymerized at room temperature. After 24 hours, release of UDMA, TEGDMA and BIS-GMA monomers were measured by High-Performance Liquid Chromatography analysis. Data analysis was performed by two-way ANOVA test, Games-Howell and Sidak post hoc tests. Results: Pre-heating did not have any statistically significant effect on the mean values of UDMA, TEGDMA and Bis-GMA elution (p>0.05). The greatest amount of released Bis-GMA and UDMA was obtained from Tetric N-Ceram Bulk-fill composite. The greatest amount of released TEGDMA was obtained from X-tra Fill composite. X-tra Base composite showed the lowest amount of monomer release (P<0.001). Conclusions: Pre-heating did not have any effect on monomer release from bulk-fill resin composites. Moreover, the amount and the type of monomers released from various bulk-fill resin composites were not similar.
Iranian endodontic journal, 2015
The aim of the present study was to evaluate the effect of different mixing techniques (conventio... more The aim of the present study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic mixing) on the physical properties the working time (WT), setting time (ST), dimensional changes (DC) and film thickness (FT)] of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA). The mentioned physical properties were determined using the ISO 6786:2001 specification. Six samples of each material were prepared for three mixing techniques (totally 36 samples). Data were analyzed using descriptive statistics, two-way ANOVA and Post Hoc Tukey's tests. The level of significance was defined at 0.05. Irrespective of mixing technique, there was no significant difference between the WT and FT of the tested materials. Except for the DC of MTA and the FT of the all materials, other properties were significantly affected with mixing techniques (P<0.05). The ultrasonic technique decreased the ST of MTA and CEM cement and increased the ...
Journal of Endodontics, 2013
Introduction: The aim of the present study was to compare the effect of blood contamination on re... more Introduction: The aim of the present study was to compare the effect of blood contamination on retention characteristics of white mineral trioxide aggregate (WMTA) and calcium-enriched mixture (CEM) in reconstructions of the furcation area. Methods: Furcal perforations, measuring 1.3 mm in diameter and 2 mm in height, were produced in 180 human mandibular first molars. The teeth were divided into 12 groups of 15. WMTA and CEM were used in groups 1-6 and 7-12, respectively, for perforation repair. In groups 1, 3, 5, 7, 9, and 11 the walls of the perforated area were contaminated with blood; normal saline was injected in the remaining groups. Push-out test was carried out in groups 1, 2, 7, and 8 after 24 hours, in groups 3, 4, 9, and 10 after 72 hours, and in the remaining groups 7 days after placement of the materials by using a Universal test machine. To evaluate the failure modes, the samples were sectioned at furcation floor area, divided in two in the vertical direction, and evaluated under a stereomicroscope at Â40 magnification. Data were analyzed with multivariate analysis of variance and post hoc Tukey tests. Results: The highest (6.75 MPa) and lowest (1.77 MPa) bond strength values were recorded in groups CEM/no blood contamination at 7 days and MTA/blood contamination at 24 hours, respectively. There were no statistically significant differences in bond strength between MTA and CEM (P < .05). However, there were significant differences in bond strength between blood-contaminated and uncontaminated groups in both materials (P < .05); time had exerted a significant effect on the bond strength of the study groups (P < .05). Failure patterns were of the mixed type in all the samples. Conclusions: Resistance of both WMTA and CEM to displacement was similar, and elapse of time from 24 hours to 7 days and contamination resulted in an increase and decrease in bond strength of these 2 materials to dentin, respectively.
Journal of Dental Research, Dental Clinics, Dental Prospects, 2020
The journal of contemporary dental practice, 2012
Aim: The aim of the present study was to evaluate the effect of three methods of composite fiber ... more Aim: The aim of the present study was to evaluate the effect of three methods of composite fiber placement along with siloranebased composite resin on cuspal deflection and fracture strength of root-filled maxillary premolars. Materials and methods: Mesio-occluso-distal cavities were prepared in 60 extracted premolars subsequent to endodontic treatment. The remaining thickness of buccal and lingual walls at height of contour was 2.5 ± 0.2 mm and the gingival cavosurface margin was 1.5 mm coronal to cementoenamel junction. Subsequent to measurement of primary intercuspal distances, the teeth were randomly divided into four groups. In group 1, the cavities were only filled with Filtek Silorane composite resin. In the other three groups, preimpregnated glass fibers were placed at gingival, middle and occlusal thirds respectively, and the cavities were restored similar to the group 1. Cuspal deflection was recorded in micrometer using a stereomicroscope. Fracture strength of the samples was measured in Newton subsequent to thermocycling. Data was analyzed using Kruskal-Wallis, Mann-Whitney U, one-way ANOVA and post-hoc Tukey tests at a significance level of p < 0.05. Results: The highest cuspal deflection was recorded in the group 1, and the difference between group 1 and other groups was significant (p < 0.001). Fracture resistance in group 4 was significantly higher than that in other groups (p < 0.001). Conclusion: In restoring root-filled premolars with siloranebased composite resins, cuspal deflection decreased with the use of preimpregnated glass fibers. Clinical significance: Using preimpregnated glass fibers along with silorane-based composite resin may lead to better results in cuspal deflection and fracture resistance of endodonticallytreated maxillary premolars.
PubMed, 2014
Background and aims. The aim was to evaluate the effect of casein phosphopeptide-amorphous calciu... more Background and aims. The aim was to evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on microtensile bond strength (μTBS) to carious affected dentin (CAD) using etch-and-rinse and self-etch adhesive systems. Materials and methods. The occlusal surface of 32 human molars with moderate occlusal caries was removed. Infected dentin was removed until reaching CAD and the teeth were randomly divided into two groups based on the Single Bond (SB) and Clearfil SE Bond (CSE) adhesive systems. Before composite resin bonding, each group was subdivided into three subgroups of ND, CAD and CPP-ACP-treated CAD (CAD-CPP) based on the dentin substrate. After dissecting samples to l-mm-thick cross-sections (each subgroup: n = 13), μTBS was measured at a strain rate of 0.5 mm/min. Data was analyzed using two-way ANOVA, independent samples t-test and post-hoc Tukey tests (α=0.05). Results. Bond strength of both adhesive systems to ND was significantly higher than that to CAD (P <0.001) and CAD/CPP (P < 0.001). There were no significant differences between the μTBS of SB to CAD and CAD-CPP (P > 0.05).μTBS of CSE to CAD-CPP was higher than that to CAD; however, the difference was not significant (P > 0.05). Significant differences were found between SB and CSE systems only with CAD substrate (P < 0.001). Conclusion. Regardless of the adhesive system used, surface treatment of CAD with CPP-ACP did not have a significant effect on bond strength. However, bond strength to CAD was higher with SB rather than with CSE.
Operative Dentistry, Sep 1, 2012
In order to avoid the negative effect of contamination of composite resins with powdered latex gl... more In order to avoid the negative effect of contamination of composite resins with powdered latex gloves on the bond strength of two-step self-etching adhesive systems, the use of unpowdered latex gloves is recommended with these adhesive systems.
Journal of Dental Research, Dental Clinics, Dental Prospects
Background. Contamination of dentin surface is one of the common problems in restorative dentistr... more Background. Contamination of dentin surface is one of the common problems in restorative dentistry. The aim was to investigate the effects of different surface contaminators on the dentin shear bond strength (SBS) of universal adhesive system (UAS) applied in etch-and-rinse (ER) and self-etch (SE) strategies. Methods. One hundred forty-four maxillary anterior sound human teeth were divided into six groups based on the types of surface contaminators: no surface contaminator (control) and experimental groups contaminated with blood, saliva, aluminium chloride (ALC), ferric sulphate (FS), and caries disclosing agent (CDA). Then, each group was further subdivided into two, based on the application strategy of UAS (ER and SE). After applying the adhesive according to the manufacturer’s instructions, and bonding cylindrical composite samples, the SBS was measured. The data were analysed using two-way ANOVA, Tukey’s HSD test and t test (P<0.05). Results. The SBS in all contaminated grou...
Journal of Clinical and Experimental Dentistry
Background: Bond strength of indirect restorations is a very important issue that should be given... more Background: Bond strength of indirect restorations is a very important issue that should be given special attention. Immediate dentin sealing (IDS) technique has been suggested in recent years. The aim of the present study was to investigate the effect of different strategies of universal adhesive application for immediate and delayed dentin sealing (DDS) on the microtensile bond strength (μTBS) of self-adhesive resin cement with and without aging. Material and Methods: In this experimental study, 24 healthy human third molars were selected. After exposing the occlusal dentin, the teeth were randomly divided into two groups of 12 based on the All-Bond Universal adhesive application strategy (etch-and-rinse or self-etch). Each group was further subdivided into two (n=6) based on IDS or DDS technique. Then composite blocks were cemented on the occlusal surface with self-adhesive resin cement. After cutting the samples into 1 mm 2 cross-sections, half of the samples of each subgroup were subjected to µTBS test after one week, and the other half were tested under μTBS after 10,000 thermal cycles. Data were analyzed using three-way ANOVA (P<0.05). Results: μTBS was significantly affected by all three factors of bond strategy, sealing technique and aging. There was also a significant interaction between the three factors. Conclusions: Immediate dentin sealing improved μTBS. The etch-and-rinse strategy resulted in higher μTBS, while aging led to a decrease in μTBS.
Journal of Dental Research, Dental Clinics, Dental Prospects
Background. Considering the increased use of preheating and novel resin-based materials to restor... more Background. Considering the increased use of preheating and novel resin-based materials to restore teeth, the present study investigated the impact of preheating on the flexural strength of a giomer and compared it with a nanohybrid composite resin. Methods. Two restorative materials (Beautifil II giomer and Alpha III nanohybrid composite resin) were used. Thirty rod-shaped samples (adding up to 60 samples) were prepared from the materials above and divided into two subgroups: with and without preheating (n=15). Before sample preparation, the giomer and nanohybrid composite resin tubes were preheated at 68ºC for 15 minutes in the preheating subgroups. In the subgroups without preheating, the tubes were kept in a room at 25ºC. Then the flexural strength was compared between the two groups with two-way ANOVA at a significance level of P<0.05. Results. The results showed significantly higher flexural strength in the preheated subgroups than in the non-preheated subgroups (P<0.001...
Dental Research Journal
Background: Cention N has been introduced as an alternative material for amalgam. The purpose was... more Background: Cention N has been introduced as an alternative material for amalgam. The purpose was to investigate the flexural strength and microhardness of this material in self-cure and dual-cure modes before and after thermocycling. Materials and Methods: In this experimental study, 40 samples of Cention N were prepared in order to determine and compare the microhardness. Half of the samples were set by self-cure method and the other half with dual-cure method. The Vickers microhardness test was performed once after 24 h and again after 10000 thermocyclings. Three-point flexural test was used to determine and compare the flexural strength of 52 rod-shaped samples. Half of the samples were set by self-cure method and the other half with dual-cure method. Among 26 samples in each group, 13 samples were randomly selected and three-point flexural test was performed after 24 h and for another 13 samples after 10,000 thermocyclings. Data were analyzed using two-way ANOVA and paired samples t-test (P < 0.05). Results: There was a statistically significant difference between the mean of microhardness values in two curing methods (P < 0.001) and in two storage conditions (P < 0.001). The mean of dual-cure microhardness (100.99 ± 7.22) was higher than that of self-cure (64.61 ± 12.51) and the mean value associated with pre-thermocycling (89.75 ± 15.84) was higher than that of the post-thermocycling (76.44 ± 23.56). There was no statistically significant difference between the mean flexural strength in the two curing methods (self-cure [72.85 ± 16.26], dual cure [79.87 ± 23.07]; [P > 0.05]). However, the mean flexural strength without thermocycling (85.98 ± 21.74) was higher than that of the thermocycled group (64.24 ± 6.40) (P < 0.001). Conclusion: The microhardness of Cention N in dual-cure mode was higher than that of self-cure mode, but the flexural strength of dual-cure was not significantly different from that of self-cure. Thermocycling had a significant effect on the microhardness and flexural strength.
پانزدهمین کنگره انجمن متخصصین دندانپزشکی ترمیمی ایران, 2015
دوازدهمین کنگره بین المللی انجمن متخصصین دندانپزشکی ترمیمی ایران, 2012
پانزدهمین کنگره انجمن متخصصین دندانپزشکی ترمیمی ایران., 2015
پانزدهمین کنگره انجمن متخصصین دندانپزشکی ترمیمی ایران, 2015
Journal of dental research, dental clinics, dental prospects, 2021
Background. Prevention of dentinal crack formation is of utmost importance in endodontic treatmen... more Background. Prevention of dentinal crack formation is of utmost importance in endodontic treatment. This study aimed to evaluate the effect of RaCe, ProTaper, and V-Taper rotary systems on dentinal crack formation in three root regions during endodontic treatment. Methods. Seventy human mandibular first molars were selected randomly, and their distal roots were used. Ten samples were assigned to the control group, and sixty samples were assigned to three groups (n=20). Each group was prepared with RaCe, ProTaper, or V-Taper rotary files according to the manufacturers' instructions. A stereomicroscope was used to view cracks at ×40 magnification. Friedman's, chi-squared, and Kruskal-Wallis tests were used for statistical analysis of data (P < 0.05). Results. A comparison of the three rotary systems did not reveal any significant differences in the number of cracks between the three root thirds evaluated (P > 0.05). A comparison of the number of cracks in the coronal, mi...
Maedica, 2020
Objectives: The present study aimed to evaluate the effect of curing time and bleaching agents on... more Objectives: The present study aimed to evaluate the effect of curing time and bleaching agents on microhybrid composite resin surface microhardness. Material and method: A total of 180 microhybrid composite resin disks were divided into two groups in terms of curing time: 40 s, 60 s. Then, each group was divided into three subgroups: control (distilled water), home bleaching (15% carbamide peroxide) and office bleaching (40% hydrogen peroxide). Surface microhardness of the samples was determined by using Vickers hardness test both at baseline and after the completion of the tests. Two-way ANOVA and Tukey HSD tests were used to analyze and compare microhardness changes between groups. Statistical significance was defined at P<0.05. Results: Based on the two-way ANOVA, curing time, bleaching method, and cumulative effect of these two variables significantly affected composite resin microhardness (P<0.001). Tukey HSD tests showed that microhardness had significantly decreased in ...
iranian endodontic journal, 2019
Introduction: Relining fiber posts using composite resins helps the posts adapt to the anatomical... more Introduction: Relining fiber posts using composite resins helps the posts adapt to the anatomical space of the root canals. The aim of this study was to evaluate the effect of composite resin type on the push-out bond strength of anatomical fiber posts to intra canal dentin. Methods and Materials: Forty-eight bovine upper incisors were prepared for post space after root canal therapy and randomly divided in to six groups. Five different types of composite resin (GrandioSO, GrandioSO Heavy Flow, X-tra Fil, X-tra base and everX Posterior) were used for relining the prepared fiber posts. In the control group, the prepared post was cemented into the post space without relining. Cervical, middle and apical cross-sections were achieved from each root and push-out test was conducted at a crosshead speed of 0.5 mm/min. One sample from each group was scanned using a micro-CT scanner which provided views from the apical, middle and coronal thirds. Data were analyzed using Kolmogorov-Smirnov t...
Journal of Clinical and Experimental Dentistry, 2020
Background: The present study was aimed to evaluate the effect of pre-heating of bulk-fill resin ... more Background: The present study was aimed to evaluate the effect of pre-heating of bulk-fill resin composites on monomer elution from them. Material and Methods: Three different types of resin composites were used including Tetric N-Ceram Bulk Fill, X-tra Fill and X-tra Base. 10 cylindrical samples were prepared from each resin composites. Before light curing, 5 samples were pre-heated until reaching 68˚C, then 5 other samples were polymerized at room temperature. After 24 hours, release of UDMA, TEGDMA and BIS-GMA monomers were measured by High-Performance Liquid Chromatography analysis. Data analysis was performed by two-way ANOVA test, Games-Howell and Sidak post hoc tests. Results: Pre-heating did not have any statistically significant effect on the mean values of UDMA, TEGDMA and Bis-GMA elution (p>0.05). The greatest amount of released Bis-GMA and UDMA was obtained from Tetric N-Ceram Bulk-fill composite. The greatest amount of released TEGDMA was obtained from X-tra Fill composite. X-tra Base composite showed the lowest amount of monomer release (P<0.001). Conclusions: Pre-heating did not have any effect on monomer release from bulk-fill resin composites. Moreover, the amount and the type of monomers released from various bulk-fill resin composites were not similar.
Iranian endodontic journal, 2015
The aim of the present study was to evaluate the effect of different mixing techniques (conventio... more The aim of the present study was to evaluate the effect of different mixing techniques (conventional, amalgamator and ultrasonic mixing) on the physical properties the working time (WT), setting time (ST), dimensional changes (DC) and film thickness (FT)] of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA). The mentioned physical properties were determined using the ISO 6786:2001 specification. Six samples of each material were prepared for three mixing techniques (totally 36 samples). Data were analyzed using descriptive statistics, two-way ANOVA and Post Hoc Tukey's tests. The level of significance was defined at 0.05. Irrespective of mixing technique, there was no significant difference between the WT and FT of the tested materials. Except for the DC of MTA and the FT of the all materials, other properties were significantly affected with mixing techniques (P<0.05). The ultrasonic technique decreased the ST of MTA and CEM cement and increased the ...
Journal of Endodontics, 2013
Introduction: The aim of the present study was to compare the effect of blood contamination on re... more Introduction: The aim of the present study was to compare the effect of blood contamination on retention characteristics of white mineral trioxide aggregate (WMTA) and calcium-enriched mixture (CEM) in reconstructions of the furcation area. Methods: Furcal perforations, measuring 1.3 mm in diameter and 2 mm in height, were produced in 180 human mandibular first molars. The teeth were divided into 12 groups of 15. WMTA and CEM were used in groups 1-6 and 7-12, respectively, for perforation repair. In groups 1, 3, 5, 7, 9, and 11 the walls of the perforated area were contaminated with blood; normal saline was injected in the remaining groups. Push-out test was carried out in groups 1, 2, 7, and 8 after 24 hours, in groups 3, 4, 9, and 10 after 72 hours, and in the remaining groups 7 days after placement of the materials by using a Universal test machine. To evaluate the failure modes, the samples were sectioned at furcation floor area, divided in two in the vertical direction, and evaluated under a stereomicroscope at Â40 magnification. Data were analyzed with multivariate analysis of variance and post hoc Tukey tests. Results: The highest (6.75 MPa) and lowest (1.77 MPa) bond strength values were recorded in groups CEM/no blood contamination at 7 days and MTA/blood contamination at 24 hours, respectively. There were no statistically significant differences in bond strength between MTA and CEM (P < .05). However, there were significant differences in bond strength between blood-contaminated and uncontaminated groups in both materials (P < .05); time had exerted a significant effect on the bond strength of the study groups (P < .05). Failure patterns were of the mixed type in all the samples. Conclusions: Resistance of both WMTA and CEM to displacement was similar, and elapse of time from 24 hours to 7 days and contamination resulted in an increase and decrease in bond strength of these 2 materials to dentin, respectively.
Journal of Dental Research, Dental Clinics, Dental Prospects, 2020