maryam ghavam

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 questionnaires, data were transferred to a computer and the differences in judgments of professionals and laypeople were analyzed using the Mann Whitney test.
No significant difference was found in the judgments of professionals and laypeople on evaluating overall smile esthetics, gingival display and alignment of teeth except for the slide showing a reverse smile arc.
Laypeople and professionals had similar perceptions of smile esthetics. Thus, it appears that clinicians can rely on the judgment of laypersons in esthetic dental treatments.

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. 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. 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 repeated measures of ANOVA model (α=0.05). The primary and secondary microhardness of P90 was significantly lower than that of Z350, and Z250 (p< 0.001). Microhardness of Z350 was also lower than that of Z250 (p= 0.002). On day 28, microhardness of P90 was lower than Z250 and Z350 (p< 0.001); however, microhardness values of Z250 and Z350 were not significantly different (p= 0.054). Microhardness of specimens subjected to non-alcoholic beer was significantly lower than that of controls (p= 0.003). Meanwhile, the microhardness value of resins in orange juice was somewhere between the two mentioned values with no significant difference with any of them (p> 0.05). Although 28 days of immersion in 100% orange juice and non-alcoholic beer decreased the microhardness of all specimens, P90 experienced the greatest reduction of microhardness and non-alcoholic beer had the highest effect on reducing microhardness.

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 composite or two methacrylate-based composites. 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 underwent 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. No significant differences were found between the composites in the control groups in enamel (P=0.171) or dentin (P=0.094) margins. After bleaching, microleakage of Z250 (at the occlusal (P=0.696) or gingival (P=0.867) margins), Z350 (at the occlusal (P=0.323) margin) and P90 (at the occlusal (P=0.316) or gingival (P=0.281) margins) did not change significantly. No significant differences were noted between the bleached and control subgroups of Z250 and P90 in enamel or dentin margins. Microleakage of Z350 composite was reduced at the gingival margin compared to the control group, but no significant difference was observed at the occlusal margin. Microleakage of silorane-based composite in gingival margin was significantly more than two metacrylate-based composites.

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. 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. 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=0.899).Panavia F2 showed a higher bond strength to sandblasted Verabond compared to RelyX Unicem (P=0.003). The bond strength of RelyX Unicem was significantly higher to Silano-Pen treated Verabond (P=0.011). The bond strength of the cements to sandblasted Degubond 4 showed no significant difference (P=0.59). RelyX Unicem had a higher bond strength to Silano-Pen treated Degubond 4 (P=0.035). The bond strength of resin cements to Verabond alloy was significantly higher than Degubond 4. RelyX Unicem had a higher bond strength to Silano-Pen treated alloys. Surface treatments of the alloys did not affect the bond strength of Panavia F2.

Urinary tract infection (UTI) is one of the most common types of infection which can occur in all age groups. The use of catheters is one of the most important underlying factors, especially when they are left in place for a long time.. This study aimed to investigate the effect of sterile catheter fixation on bacteriuria and urinary tract infections..Patients and The present research is a clinical trial study. The patients who had urinary catheters based on the existing indications in 2012, hospitalized in Imam Hussein (AS) Hospital, Tehran enrolled in the study. Patients were divided into two groups. The first group consisted of patients whom the catheters were installed by a medical intern in the emergency department. The second group consisted of patients whom the catheters were installed in the same department by two medical interns using a completely sterile method especially at fixation and lubrication steps. The information contained in the patients'' check list including the background information, age, hospitalization days, history of urinary catheters, history of infection and results of urine culture and analysis.. A total of one hundred and eighty-eight individuals with the mean age of 39.1 ± 19 years (age range between 18 - 77 years old) enrolled in this study. There was no significant difference in the number of hospitalization days between the two groups (P > 0.05). The number of hospitalization days and incidence of infection were significantly correlated (P < 0.05). The results showed a total OR of 1.5 indicating that the risk of infection is higher in the first group. Overall, the rate of urinary tract infection in this study was 16.4% while this rate was 19.1% and 13.8% in the first and second groups, respectively. The statistical tests showed significant difference between two groups in the incidence of urinary tract infection (P < 0.05), and also positive urine cultures were reported for twelve patients in the first group and nine patients in the second group. Escherichia coli (E. coli) was the most common infective microorganism in both groups, which was observed in 66.6% of the first and 88.8% of the second groups. The frequency of Gram-negative bacteria was 10 cases (83.3%) in the first group and 8 cases (88.8%) in the second group.. According to this study, employing the principles of sterile techniques during the catheterization and sterilization of instruments, as well as skills and experiments of individuals in this process, are the most important factors that can significantly reduce the number of infections after catheterization..

The aim of this study was to assess the effect of bleaching on elution of monomers from nanofilled and microhybrid composites. 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). 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 monomer (P<0.001). Increasing both the concentration of H2O2, and the immersion time, increased the release of TEGDMA (P<0.001). Polishing had no effect on release of this monomer (P=0.952). Supreme released more Bis-GMA than Z250 (P=0.000). The more concentrated H2O2 caused more elution of Bis-GMA (P= 0.003); while the effect of immersion time was not significant (P=0.824). Polishing increased the release of Bis-GMA (P=0.001). Neither the type of composite nor Bleaching had any effect on release of UDMA (P=0.972) and (P=0.811) respectively. Immersion duration increased the release of UDMA (P=0.002), as well as polishing (P=0.024). Bleaching increased the release of monomers. Nanofilled composites released more monomer than the microfilled.

Tooth-colored non-metal posts are adhered to the canal walls with the use of resin cements and dentin adhesives. Degree of conversion of these cements is especially important to ensure the durability of the restoration. The present study aimed at evaluating the degree of conversion (DC%) of self-cure and dual-cure resin cements at different depths and time points when using a DT. Light Post.

In this experimental study, metal molds with 5 and 10 mm heights and internal diameter of 0.8 mm were used. Posts were vertically placed in the center of molds. Spectrum of absorption of the dual cure cement was measured before curing using Fourier transform infrared spectroscopy device. The uncured samples were then removed from the device and placed beneath the molds. After light irradiation, samples were transferred again to the FTIR device and their spectrum of absorption was measured. DC% was calculated using the relevant formula. For self-cure cements, spectrum of absorption was measured at 0, 2, 5, 10 and 15 minutes by the FTIR. Results were statistically analyzed using SPSS software.

Self-cure cement had a DC of 5% at 0, 2, 5 and 10 minutes and a DC of 20% at 15 minutes. DC of the dual-cure cement was 44%, 15% and 8% at 0, 5 and 10 mm depths, respectively. Two-way ANOVA and Tukey’s Post Hoc test (HSD) revealed that in the dual-cure cement the DC at 5 and 10 mm depths was significantly different (P<0.05). DC was 20% at 15 minutes which was the highest.

DC% of the dual-cure cement was higher than that of the self-cure cement which is attributed to the optimal characteristics of the dual-cure cement and also the ability of fiber post to pass light.

The reported bond strengths of resin cements to metal alloys depend on the metal used, the conditioning methods and the adhesive resins. The aim of this study was to evaluate the bond strength of resin cements to two alloys (Degubond 4 and Verabond) after sandblasting or using Silano-Pen. Eighty disk shaped specimens (6mm diameter and 2mm thickness) of Verabond or Degubond 4 were cast according to the manufacturer's instructions. After mounting in auto polymerizing acryl, all samples were polished with a 600 grit silicon carbide paper under water. Half of each alloy’s samples were randomly sandblasted with 50 µ Al2O3 and the other half were flamed with Silano-Pen device after sandblasting with 110 µ Al2O3. Cylinders of composite resin (Z250) were cured and then cemented to the prepared substrates by either Panavia F2 or RelyX Unicem. All specimens were stored in distilled water at 37oC for 24 hours and were subjected to 2000 thermal cycles (5-55oC), then submitted to shear bond strength (SBS) test using Universal Testing Machine at 0.5mm/min speed, until failure. SBS was analyzed by three way ANOVA (α=0.05). Failure patterns were determined using stereomicroscope with 40X magnification. Both cements provided stronger bond to Verabond compared to Degubond 4 (p<0.001). Comparing the surface treatments, Silano-Pen provided higher SBS of RelyX Unicem to both alloys. Panavia cement resulted in higher bond strengths to sandblasted Verabond alloy (p=0.003), but after treatment with Silano-Pen device RelyX Unicem showed higher bond (p=0.011). When cementing Verabond or Degubond 4 by RelyX Unicem, Silano-Pen provided a stronger bond, but in case of using Panavia F2, treatment with Silano-Pen or sandblast resulted no difference in bond strength.

The main objective of using adhesive material is the improvement of restorative materials bonding to dentin surface in clean environment. The aim of this study was to investigate the effect of EDTA on bond strength of composite resin to dentin surface when used at different times and concentrations prior to application of adhesive systems by employing Scanning Electronic Microscope (SEM). A total of 100 dentin samples were prepared from 50 human premolars. These samples were divided into two groups according to bonding type (Clearfil SE Bond =group I, Futurbond NR=group II) and each one was classified 5 subgroups according to time and concentration of EDTA as follows: 1 – Control. 2- EDTA 15%, 30 seconds. 3 – EDTA 15%, 60 seconds. 4 – EDTA 24%, 30 seconds. 5 – EDTA 24%, 60 seconds. These samples were conditioned and composite cylinders were adhered to them. After 500 cycles of thermocycling, the testing for micro-shear bond strength was conducted on these samples. Another 10 samples were demineralized for 30 seconds with 6NHCL and deproteinized with 2.5% Naocl for 10 minutes, air dried with desiccators and viewed under SEM. Data were analyzed using one-way as well as three-way ANOVA and Tukey tests. The mean Micro-shear bond strength in group I (Clearfil SE bond) were: 31.88 (± 13) for subgroup 1, 28.4 (± 13) in subgroup 2, 29.8 (± 9) in subgroup 3, 29.2 (± 11) in subgroup 4, and 32.7 (± 12) in subgroup 5. The mean Micro-shear bond strength in group 2 (Futurbond NR): were: 22.6 (± 10) for subgroup 1, 28.5 (± 9) in subgroup 2, 27.3 (± 10) subgroup 3, 32.4 (± 15) in subgroup 4, and 31.1 (± 14) in subgroup 5. There were no significant differences between the samples conditioned and the ones not conditioned with EDTA, time and the concentration of EDTA applied and also the two bonding types. EDTA conditioning prior to use of the two bonding agents under investigation in this study did not improve the bonding strength of the self etch systems, neither did the time and the concentration of EDTA applied.

Dental handpieces are the most commonly used instruments in dentistry and their cross contamination is very high due to their direct contact with blood and saliva. The purpose of this study was to evaluate the antiviral effects of formalin tablets and autoclave on internal lumens of dental handpieces. This experimental study was designed in order to evaluate the effect of different materials and methods of sterilization and disinfection on virus elimination from internal spaces and interior chambers of dental turbines. Four study groups were composed of: 1) Vacuum autoclave, 2) Non vacuum autoclave, 3) Ten Para Formaldehyde tablets, and 4) Twenty Para Formaldehyde tablets. Nine turbines were tested in each group after preliminary washing, drying and autoclaving. The internal tubes and spaces were then contaminated with Polio and Herpes Simplex virus type I. Antiviral agents and devices were used according to the manufacturers’ instructions. Two cell culture samples were obtained from each handpiece, after washing them with sterile distilled water and MEM (Minimum Essential Medium). In each group one handpiece was designated as control. The culture results were recorded after one week. Autoclaving was perfectly effective on both Polio and Herpes Simplex virus type I in all groups (vacuumed, non-vacuumed, with or without lubricant). Formalin tablets were 100% effective only on polio virus, and in the 20 tablet group turbines without lubricant. These tablets killed the Herpes Simplex virus in all groups. According to the results of this study, autoclaving is the best method of virus elimination in dental handpiece.

Prepared cavities are usually treated with liners prior to amalgam placement. Light cured glass ionomer (RMGI) have been widely used for this purpose. The aim of this study was to compare the effect of RMGI on decreasing postoperative sensitivity with a new method of applying self etch bonding and glass ionomer simultaneously. In a blind randomized clinical trial study, A total of 36 patients with 2 deep caries in their posterior teeth (cavities with less than 2 mm distance from pulp in radiography) were included. Diagnostic tests (cold–heat, percussion, electric pulp test) were performed for each tooth prior to final restoration. After cavity preparation, one tooth was treated by light cured glass ionomer, the next one with SE bond and glass ionomer randomly, followed by amalgam restoration. Diagnostic tests were performed three days, thirty days and three months after amalgam restoration. The statistical analysis was performed using SPSS software version 11.5 as well as Friedman and Wilcoxon signed-rank tests. In second follow up, the sensitivity to cold was significantly less than the conventional method (P<0.05) in our suggested compound method. However, there was no significant difference between the two groups when using the other vitality tests. Using SE bond and light cured glass ionomer simultaneously was an effective new method of decreasing the postoperative sensitivity in short term, (1 month), although, there was no difference between the two groups in the long term.

Bacterial contamination of dental materials and devices used in dental clinics and laboratories can lead to infectious diseases in patients, dentists and dental care providers. The aim of this study was to examine bacterial contamination of four dental materials. In this analytic-descriptive study, flour of pumice, zinc oxide powder, prophylaxis paste and wooden wedges of available commercial brands were tested. To assure an examiner-blind study, the samples were coded in the microbiology laboratory. In sterile conditions, the samples were inoculated in tryptycase soy broth and sodium tioglycolate for aerobic and anaerobic bacterial growth, respectively. The media was then incubated in 35 degrees centigrade and checked daily. Flour of pumice showed contamination to coagulase-negative staphylococci, enterococcus faecallis, bacillus and diphteroid. Some of the prophylaxis pastes were contaminated with micrococcus roseous, coagulase-negative staphylococci and diphteroid. One brand of wooden wedges demonstrated contamination to staphylococcus, diphteroid and bacilli. Zinc oxide powders were not contaminated. None of the samples showed contamination to anaerobic bacteria. Some of the investigated materials showed bacterial contamination, but the identified bacteria are not pathogen in normal situations.