Objectives: The aim of this study was to assess the effect of 30 % hydrogen peroxide on the micro... more Objectives: The aim of this study was to assess the effect of 30 % hydrogen peroxide on the microleakage of class V cavities restored with either a silorane-based compo-site or two methacrylate-based composites. Materials and Methods: A total of 96 standard class V cavities (1.5 × 2 × 3 mm) were prepared on the buccal surface of sound extracted human premolars with both enamel and dentin margins and randomly assigned into three groups of Filtek P90 (group A) with its respective bonding (P90 system adhesive), Filtek Z250 (group B) and Filtek Z350XT (group C), both with Adper Prompt L-Pop bonding. The teeth were subjected to thermocycling (1000×, 5–55ºC) and half of them randomly under-went bleaching (30 % hydrogen peroxide, 15 min, three times), while the remaining half (control) were not bleached. Dye penetration was measured following immersion in 2 % basic fuchsin for 24 h. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at 95 % CI. Results: No signi...
Methods: In this experimental study new dental adhesive blends were prepared by mixing doxycyclin... more Methods: In this experimental study new dental adhesive blends were prepared by mixing doxycycline monohydrate( 0.0, 0,25,0.5 and 1 wt.%) with monomers. Experimental adhesives were divided into four groups according to the amount of doxycycline. The monomers were composed of 12% Bis-GMA and 10% TMPTMA , 28% HEMA and 50% ethanol by weight for all groups. Comphorquinone and amines were chosen as photo initiator system. Degree of conversion of all adhesives was measured using FTIR spectroscopy. All specimens were stored for 24 hours in 37°C ...
Objective: The aim of this study was to assess the effect of bleaching on elution of monomers fro... more Objective: The aim of this study was to assess the effect of bleaching on elution of monomers from nanofilled and microhybrid composites. Materials and Methods: 80 samples (5mm diameter and 3mm thickness) of each composite were prepared. After curing, half of them were randomly polished. Each group was divided into 8 subgroups and immersed in water or 10%, 20 % and 30% H2O2 for 3 or 8 hours. Eluted Bis-GMA (Bis-phenol A Glycidyl Dimethacrylate),
Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five a... more Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Materials and Methods: Class V cavities (4x2x2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind...
Objectives: This study aimed to assess and compare the perception of laypersons and dental profes... more Objectives: This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. Materials and Methods: A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scorin...
Objective: The aim of this study was to assess the effect of bleaching on elution of monomers fro... more Objective: The aim of this study was to assess the effect of bleaching on elution of monomers from nanofilled and microhybrid composites. Materials and Methods: 80 samples (5mm diameter and 3mm thickness) of each composite were prepared. After curing, half of them were randomly polished. Each group was divided into 8 subgroups and immersed in water or 10%, 20% and 30% H2O2 for 3 or 8 hours. Eluted Bis-GMA (Bis-phenol A Glycidyl Dimethacrylate), TEGDMA (Triethyleneglycol Dimethacrylate), UDMA (Urethane Dimethacrylate) and BisEMA (Bis-phenol A ethoxylate Dimethacrylate) were quantified by high performance liquid chromatography and the results were analyzed by univariate ANOVA and t-test (P<0.05). Results: Bleach significantly increased the overall release of monomers (P<0.001); TEGDMA was released more than Bis-GMA (P<0.001). Supreme released more TEGDMA compared to Z250 (P<0.001). Bleaching increased the release of this mon-omer (P<0.001). Increasing both the concentra...
Statement of the Problem: Acidic foods and drinks can erode composite resins. Silorane-based comp... more Statement of the Problem: Acidic foods and drinks can erode composite resins. Silorane-based composite is a new low shrinkage composite with higher hydro-phobicity which might resist the erosive effect of beverages. Purpose: The aim of this study was to determine the effects of 100 % orange juice and non-alcoholic carbonated beer on microhardness of a silorane-based composite in comparison with two methacrylate-based composite resins. Materials and Method: Ninety disc-shaped composite specimens were fabricat-ed of Filtek P90, Filtek Z350 XT Enamel and Filtek Z250 (3M-ESPE) (n=30) and randomly divided into 3 subgroups of 10.Group 1 was immersed in distilled water, group 2 in 100 % orange juice, and group 3 in non-alcoholic beer for 3 h/day. Primary, secondary and final Vickers microhardness tests were performed at the beginning of the study and 7 and 28 days later. Surface of 2 specimens in each group was evaluated under scanning electron microscope on day 28. Data were analyzed usin...
To evaluate the degree of conversion of dual-cured resin cements applied for luting of translucen... more To evaluate the degree of conversion of dual-cured resin cements applied for luting of translucent and opaque fibre posts. Two dual-cured resin cements, RelyX ARC and Nexus 2, were used to cement 2 types of tooth-coloured fibre posts, D.T. Light-Post (translucent) and D.T. White-Post (opaque). The degree of conversion for each resin cement was measured. Post-curing polymerization and chemical curing of the cements were also measured. The degree of conversion was measured at various distances (4, 6 and 8 mm) from the tip of the light-curing unit by Fourier transform infrared spectroscopy. The data were analyzed with analysis of variance and post hoc tests (α = 0.05). The degree of conversion of the dual-cure cements was significantly higher with the D.T. Light-Posts than with the D.T. White-Posts (p < 0.05). No significant difference was observed in the degree of conversion at different depths for the RelyX ARC resin cement in conjunction with the D.T. Light-Posts (p > 0.05). T...
Journal of Dentistry of Tehran University of Medical Sciences, 2016
This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 second... more This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Class V cavities (4×2×2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind examiner observed the sections und...
Objectives: This study aimed to assess and compare the perception of laypersons and dental profes... more Objectives: This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. Materials and Methods: A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scorin...
Objectives: The bond strength of resin cements to metal alloys depends on the type of the metal, ... more Objectives: The bond strength of resin cements to metal alloys depends on the type of the metal, conditioning methods and the adhesive resins used. The purpose of this study was to evaluate the bond strength of resin cements to base and noble metal alloys after sand blasting or application of silano-pen. Materials and Method: Cylinders of light cured Z 250 composite were cemented to "Degubond 4" (Au Pd) and "Verabond" (Ni Cr) alloys by either RelyX Unicem or Panavia F2, after sandblasting or treating the alloys with Silano-Pen. The shear bond strengths were evaluated. Data were analyzed by three-way ANOVA and t tests at a significance level of P<0.05. Results: When the alloys were treated by Silano-Pen, RelyX Unicem showed a higher bond strength for Degubond 4 (P=0.021) and Verabond (P< 0.001). No significant difference was observed in the bond strength of Panavia F2 to the alloys after either of surface treatments, Degubond 4 (P=0.291) and Verabond (P=0.89...
Comparison of the Degree of Conversion of Two Resin Cements When using a Fiber Post Somayeh Kamel... more Comparison of the Degree of Conversion of Two Resin Cements When using a Fiber Post Somayeh Kameli *Zohreh Moradi Mohammad Ataei Maryam Ghavam Mohammad Javad Kharazifard Postgraduate student, Dept. of Pediatric Dentistry, Dental School, Shahed University, TehranIran. *Corresponding Author: Postgraduate student, Dept. of Operative Dentistry, Dental School, Shahed University, TehranIran. E-mail: [email protected] Associate Professor, Dept. of Polymer, Petrochemical and Polymer Research Center of Iran, TehranIran. Associate Professor, Dept. of Operative Dentistry, Dental School, Tehran University of Medical Sciences, TehranIran. Dentist, Statistician, Dental School, Tehran University of Medical Sciences, TehranIran. Abstract
Statement of the Problem Acidic foods and drinks can erode composite resins. Silorane-based compo... more Statement of the Problem Acidic foods and drinks can erode composite resins. Silorane-based composite is a new low shrinkage composite with higher hydrophobicity which might resist the erosive effect of beverages. Purpose The aim of this study was to determine the effects of 100% orange juice and non-alcoholic carbonated beer on microhardness of a silorane-based composite in comparison with two methacrylate-based composite resins. Materials and Method Ninety disc-shaped composite specimens were fabricated of Filtek P90, Filtek Z350 XT Enamel and Filtek Z250 (3M-ESPE) (n=30) and randomly divided into 3 subgroups of 10.Group 1 was immersed in distilled water, group 2 in 100% orange juice, and group 3 in non-alcoholic beer for 3 h/day. Primary, secondary and final Vickers microhardness tests were performed at the beginning of the study and 7 and 28 days later. Surface of 2 specimens in each group was evaluated under scanning electron microscope on day 28. Data were analyzed using repea...
Objectives: This study aimed to assess and compare the perception of laypersons and dental profes... more Objectives: This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. Materials and Methods: A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scorin...
OBJECTIVE To evaluate the degree of conversion of dual-cured resin cements applied for luting of ... more OBJECTIVE To evaluate the degree of conversion of dual-cured resin cements applied for luting of translucent and opaque fibre posts. METHODS Two dual-cured resin cements, RelyX ARC and Nexus 2, were used to cement 2 types of tooth-coloured fibre posts, D.T. Light-Post (translucent) and D.T. White-Post (opaque). The degree of conversion for each resin cement was measured. Post-curing polymerization and chemical curing of the cements were also measured. The degree of conversion was measured at various distances (4, 6 and 8 mm) from the tip of the light-curing unit by Fourier transform infrared spectroscopy. The data were analyzed with analysis of variance and post hoc tests (α = 0.05). RESULTS The degree of conversion of the dual-cure cements was significantly higher with the D.T. Light-Posts than with the D.T. White-Posts (p < 0.05). No significant difference was observed in the degree of conversion at different depths for the RelyX ARC resin cement in conjunction with the D.T. Li...
Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five a... more Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Materials and Methods: Class V cavities (4×2×2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind...
Background By an increase in use of composite restorations, some defects are also seen in these r... more Background By an increase in use of composite restorations, some defects are also seen in these restorations, which need to be repaired. Since complete replacement of an old restoration may compromise the tooth structure, repair of defect is a more practical approach if there is no caries recurrence. Risk of pulp injury also decreases as such. One major challenge in restoration repair is to obtain a durable bond between the new and old composite. Laser irradiation has been suggested for surface preparation of old composite. This study aimed to assess the effect of composite surface preparation with Er,Cr:YSGG laser on microtensile bond strength to new composite. Material and Methods A total of 18 blocks were fabricated in three groups of nanohybrid, microhybrid and Beautiful II giomer measuring 4x7x7 mm and subjected to 10,000 thermal cycles between 5-55°C with 30 seconds of dwell time. The samples were randomly assigned to no surface treatment (etching and bonding) or laser plus et...
This study aimed to assess the microshear bond strength of a repairing self-adhesive flowable com... more This study aimed to assess the microshear bond strength of a repairing self-adhesive flowable composite to ceramic after mechanical, chemical and laser treatment of the ceramic surface. Materials and Methods: Forty zirconia and forty feldspathic ceramic blocks measuring 8 x 8 x 2 mm were fabricated. Feldspathic blocks were divided into four groups of control (1), laser (2780 nm) (2), sandblasting + hydrofluoric (HF) acid + silane (3) and laser (2780 nm) + HF acid + silane (4). Zirconia blocks were also divided into four groups of control (1), laser (2780 nm) (2), sandblasting + Z-Prime Plus (3) and laser (2780 nm) + Z-Prime Plus (4). Vertise Flow composite was bonded to treated ceramic surfaces as a repairing material, then the samples were subjected to 1000 thermal cycles. Repair bond strength was measured by Instron machine and data were analyzed using one-way ANOVA and post hoc test (P < 0.05). Results: Maximum and minimum bond strength values were observed in zirconia-control (22.57 ± 4.76 MPa) and feldspathic-control (8.65 ± 6.41 MPa) groups, respectively. There was no significant differences between subgroups within the zirconia or feldspathic groups (P > 0.05) , however the bond strength of zirconia subgroups was significantly higher than that of feldspathic subgroups. Conclusion: Vertise Flow provides relatively good bond strength to ceramic even with no surface treatment.
This study aimed to assess and compare the perception of laypersons and dental professionals of s... more This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scoring (1-10). After completion of the q...
This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 second... more This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Class V cavities (4×2×2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind examiner observed the sections und...
Objectives: The aim of this study was to assess the effect of 30 % hydrogen peroxide on the micro... more Objectives: The aim of this study was to assess the effect of 30 % hydrogen peroxide on the microleakage of class V cavities restored with either a silorane-based compo-site or two methacrylate-based composites. Materials and Methods: A total of 96 standard class V cavities (1.5 × 2 × 3 mm) were prepared on the buccal surface of sound extracted human premolars with both enamel and dentin margins and randomly assigned into three groups of Filtek P90 (group A) with its respective bonding (P90 system adhesive), Filtek Z250 (group B) and Filtek Z350XT (group C), both with Adper Prompt L-Pop bonding. The teeth were subjected to thermocycling (1000×, 5–55ºC) and half of them randomly under-went bleaching (30 % hydrogen peroxide, 15 min, three times), while the remaining half (control) were not bleached. Dye penetration was measured following immersion in 2 % basic fuchsin for 24 h. Data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests at 95 % CI. Results: No signi...
Methods: In this experimental study new dental adhesive blends were prepared by mixing doxycyclin... more Methods: In this experimental study new dental adhesive blends were prepared by mixing doxycycline monohydrate( 0.0, 0,25,0.5 and 1 wt.%) with monomers. Experimental adhesives were divided into four groups according to the amount of doxycycline. The monomers were composed of 12% Bis-GMA and 10% TMPTMA , 28% HEMA and 50% ethanol by weight for all groups. Comphorquinone and amines were chosen as photo initiator system. Degree of conversion of all adhesives was measured using FTIR spectroscopy. All specimens were stored for 24 hours in 37°C ...
Objective: The aim of this study was to assess the effect of bleaching on elution of monomers fro... more Objective: The aim of this study was to assess the effect of bleaching on elution of monomers from nanofilled and microhybrid composites. Materials and Methods: 80 samples (5mm diameter and 3mm thickness) of each composite were prepared. After curing, half of them were randomly polished. Each group was divided into 8 subgroups and immersed in water or 10%, 20 % and 30% H2O2 for 3 or 8 hours. Eluted Bis-GMA (Bis-phenol A Glycidyl Dimethacrylate),
Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five a... more Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Materials and Methods: Class V cavities (4x2x2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind...
Objectives: This study aimed to assess and compare the perception of laypersons and dental profes... more Objectives: This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. Materials and Methods: A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scorin...
Objective: The aim of this study was to assess the effect of bleaching on elution of monomers fro... more Objective: The aim of this study was to assess the effect of bleaching on elution of monomers from nanofilled and microhybrid composites. Materials and Methods: 80 samples (5mm diameter and 3mm thickness) of each composite were prepared. After curing, half of them were randomly polished. Each group was divided into 8 subgroups and immersed in water or 10%, 20% and 30% H2O2 for 3 or 8 hours. Eluted Bis-GMA (Bis-phenol A Glycidyl Dimethacrylate), TEGDMA (Triethyleneglycol Dimethacrylate), UDMA (Urethane Dimethacrylate) and BisEMA (Bis-phenol A ethoxylate Dimethacrylate) were quantified by high performance liquid chromatography and the results were analyzed by univariate ANOVA and t-test (P<0.05). Results: Bleach significantly increased the overall release of monomers (P<0.001); TEGDMA was released more than Bis-GMA (P<0.001). Supreme released more TEGDMA compared to Z250 (P<0.001). Bleaching increased the release of this mon-omer (P<0.001). Increasing both the concentra...
Statement of the Problem: Acidic foods and drinks can erode composite resins. Silorane-based comp... more Statement of the Problem: Acidic foods and drinks can erode composite resins. Silorane-based composite is a new low shrinkage composite with higher hydro-phobicity which might resist the erosive effect of beverages. Purpose: The aim of this study was to determine the effects of 100 % orange juice and non-alcoholic carbonated beer on microhardness of a silorane-based composite in comparison with two methacrylate-based composite resins. Materials and Method: Ninety disc-shaped composite specimens were fabricat-ed of Filtek P90, Filtek Z350 XT Enamel and Filtek Z250 (3M-ESPE) (n=30) and randomly divided into 3 subgroups of 10.Group 1 was immersed in distilled water, group 2 in 100 % orange juice, and group 3 in non-alcoholic beer for 3 h/day. Primary, secondary and final Vickers microhardness tests were performed at the beginning of the study and 7 and 28 days later. Surface of 2 specimens in each group was evaluated under scanning electron microscope on day 28. Data were analyzed usin...
To evaluate the degree of conversion of dual-cured resin cements applied for luting of translucen... more To evaluate the degree of conversion of dual-cured resin cements applied for luting of translucent and opaque fibre posts. Two dual-cured resin cements, RelyX ARC and Nexus 2, were used to cement 2 types of tooth-coloured fibre posts, D.T. Light-Post (translucent) and D.T. White-Post (opaque). The degree of conversion for each resin cement was measured. Post-curing polymerization and chemical curing of the cements were also measured. The degree of conversion was measured at various distances (4, 6 and 8 mm) from the tip of the light-curing unit by Fourier transform infrared spectroscopy. The data were analyzed with analysis of variance and post hoc tests (α = 0.05). The degree of conversion of the dual-cure cements was significantly higher with the D.T. Light-Posts than with the D.T. White-Posts (p < 0.05). No significant difference was observed in the degree of conversion at different depths for the RelyX ARC resin cement in conjunction with the D.T. Light-Posts (p > 0.05). T...
Journal of Dentistry of Tehran University of Medical Sciences, 2016
This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 second... more This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Class V cavities (4×2×2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind examiner observed the sections und...
Objectives: This study aimed to assess and compare the perception of laypersons and dental profes... more Objectives: This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. Materials and Methods: A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scorin...
Objectives: The bond strength of resin cements to metal alloys depends on the type of the metal, ... more Objectives: The bond strength of resin cements to metal alloys depends on the type of the metal, conditioning methods and the adhesive resins used. The purpose of this study was to evaluate the bond strength of resin cements to base and noble metal alloys after sand blasting or application of silano-pen. Materials and Method: Cylinders of light cured Z 250 composite were cemented to "Degubond 4" (Au Pd) and "Verabond" (Ni Cr) alloys by either RelyX Unicem or Panavia F2, after sandblasting or treating the alloys with Silano-Pen. The shear bond strengths were evaluated. Data were analyzed by three-way ANOVA and t tests at a significance level of P<0.05. Results: When the alloys were treated by Silano-Pen, RelyX Unicem showed a higher bond strength for Degubond 4 (P=0.021) and Verabond (P< 0.001). No significant difference was observed in the bond strength of Panavia F2 to the alloys after either of surface treatments, Degubond 4 (P=0.291) and Verabond (P=0.89...
Comparison of the Degree of Conversion of Two Resin Cements When using a Fiber Post Somayeh Kamel... more Comparison of the Degree of Conversion of Two Resin Cements When using a Fiber Post Somayeh Kameli *Zohreh Moradi Mohammad Ataei Maryam Ghavam Mohammad Javad Kharazifard Postgraduate student, Dept. of Pediatric Dentistry, Dental School, Shahed University, TehranIran. *Corresponding Author: Postgraduate student, Dept. of Operative Dentistry, Dental School, Shahed University, TehranIran. E-mail: [email protected] Associate Professor, Dept. of Polymer, Petrochemical and Polymer Research Center of Iran, TehranIran. Associate Professor, Dept. of Operative Dentistry, Dental School, Tehran University of Medical Sciences, TehranIran. Dentist, Statistician, Dental School, Tehran University of Medical Sciences, TehranIran. Abstract
Statement of the Problem Acidic foods and drinks can erode composite resins. Silorane-based compo... more Statement of the Problem Acidic foods and drinks can erode composite resins. Silorane-based composite is a new low shrinkage composite with higher hydrophobicity which might resist the erosive effect of beverages. Purpose The aim of this study was to determine the effects of 100% orange juice and non-alcoholic carbonated beer on microhardness of a silorane-based composite in comparison with two methacrylate-based composite resins. Materials and Method Ninety disc-shaped composite specimens were fabricated of Filtek P90, Filtek Z350 XT Enamel and Filtek Z250 (3M-ESPE) (n=30) and randomly divided into 3 subgroups of 10.Group 1 was immersed in distilled water, group 2 in 100% orange juice, and group 3 in non-alcoholic beer for 3 h/day. Primary, secondary and final Vickers microhardness tests were performed at the beginning of the study and 7 and 28 days later. Surface of 2 specimens in each group was evaluated under scanning electron microscope on day 28. Data were analyzed using repea...
Objectives: This study aimed to assess and compare the perception of laypersons and dental profes... more Objectives: This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. Materials and Methods: A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scorin...
OBJECTIVE To evaluate the degree of conversion of dual-cured resin cements applied for luting of ... more OBJECTIVE To evaluate the degree of conversion of dual-cured resin cements applied for luting of translucent and opaque fibre posts. METHODS Two dual-cured resin cements, RelyX ARC and Nexus 2, were used to cement 2 types of tooth-coloured fibre posts, D.T. Light-Post (translucent) and D.T. White-Post (opaque). The degree of conversion for each resin cement was measured. Post-curing polymerization and chemical curing of the cements were also measured. The degree of conversion was measured at various distances (4, 6 and 8 mm) from the tip of the light-curing unit by Fourier transform infrared spectroscopy. The data were analyzed with analysis of variance and post hoc tests (α = 0.05). RESULTS The degree of conversion of the dual-cure cements was significantly higher with the D.T. Light-Posts than with the D.T. White-Posts (p < 0.05). No significant difference was observed in the degree of conversion at different depths for the RelyX ARC resin cement in conjunction with the D.T. Li...
Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five a... more Objectives: This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Materials and Methods: Class V cavities (4×2×2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind...
Background By an increase in use of composite restorations, some defects are also seen in these r... more Background By an increase in use of composite restorations, some defects are also seen in these restorations, which need to be repaired. Since complete replacement of an old restoration may compromise the tooth structure, repair of defect is a more practical approach if there is no caries recurrence. Risk of pulp injury also decreases as such. One major challenge in restoration repair is to obtain a durable bond between the new and old composite. Laser irradiation has been suggested for surface preparation of old composite. This study aimed to assess the effect of composite surface preparation with Er,Cr:YSGG laser on microtensile bond strength to new composite. Material and Methods A total of 18 blocks were fabricated in three groups of nanohybrid, microhybrid and Beautiful II giomer measuring 4x7x7 mm and subjected to 10,000 thermal cycles between 5-55°C with 30 seconds of dwell time. The samples were randomly assigned to no surface treatment (etching and bonding) or laser plus et...
This study aimed to assess the microshear bond strength of a repairing self-adhesive flowable com... more This study aimed to assess the microshear bond strength of a repairing self-adhesive flowable composite to ceramic after mechanical, chemical and laser treatment of the ceramic surface. Materials and Methods: Forty zirconia and forty feldspathic ceramic blocks measuring 8 x 8 x 2 mm were fabricated. Feldspathic blocks were divided into four groups of control (1), laser (2780 nm) (2), sandblasting + hydrofluoric (HF) acid + silane (3) and laser (2780 nm) + HF acid + silane (4). Zirconia blocks were also divided into four groups of control (1), laser (2780 nm) (2), sandblasting + Z-Prime Plus (3) and laser (2780 nm) + Z-Prime Plus (4). Vertise Flow composite was bonded to treated ceramic surfaces as a repairing material, then the samples were subjected to 1000 thermal cycles. Repair bond strength was measured by Instron machine and data were analyzed using one-way ANOVA and post hoc test (P < 0.05). Results: Maximum and minimum bond strength values were observed in zirconia-control (22.57 ± 4.76 MPa) and feldspathic-control (8.65 ± 6.41 MPa) groups, respectively. There was no significant differences between subgroups within the zirconia or feldspathic groups (P > 0.05) , however the bond strength of zirconia subgroups was significantly higher than that of feldspathic subgroups. Conclusion: Vertise Flow provides relatively good bond strength to ceramic even with no surface treatment.
This study aimed to assess and compare the perception of laypersons and dental professionals of s... more This study aimed to assess and compare the perception of laypersons and dental professionals of smile esthetics based on two factors namely gingival display and alignment of teeth. A total of 32 females were randomly selected among dental students in the International Campus of School of Dentistry, Tehran University of Medical Sciences (Tehran, Iran) with no previous history of esthetic dental work. Frontal photographs were obtained and cropped from the subnasal to menton areas of subjects to standardize the size of pictures. Three series of slides were prepared of the pictures using Microsoft PowerPoint software. The first series of slides were shown to familiarize the observers with the images. The second and third series were displayed for the observers and they were then asked to fill out a questionnaire. The group of observers included 10 dental specialists and 10 laypersons. Each observer was given a visual analog scale (VAS) chart for scoring (1-10). After completion of the q...
This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 second... more This study aimed to assess the effect of re-etching of desensitized dentin for five and 10 seconds on marginal microleakage of composite restorations. Class V cavities (4×2×2mm) were prepared on the buccal surfaces of 64 third molars and randomly divided into four groups of 16. In the control group, Single Bond (SB) adhesive was applied after etching. In BB+SB group, after application of BisBlock (BB) desensitizer agent (which needs etching), SB adhesive was used. In BB+5E+SB group, re-etching of dentin was done for five seconds after application of desensitizer, and then the adhesive was applied. The process in BB+10E+SB was the same as BB+5E+SB group except for re-etching time, which was 10 seconds. The cavities were restored with composite resin. After 24 hours of storage in distilled water and 10,000 thermal cycles, all samples were subjected to dye penetration test. The teeth were sectioned buccolingually in the middle of restorations. A blind examiner observed the sections und...
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