Journal of Islamic Dental Association of IRAN
Volume:26 Issue: 4, 2015

Assure universal bonding resin is marketed with fluoride releasing potential. The manufacturer claims that it provides adequate bond strength between the bracket and amalgam and porcelain. This study compared the shear bond strength of Transbond XT and Assure universal bonding resin to stainless steel brackets, amalgam and porcelain in vitro. In this in vitro study, 20 standard brackets of the maxillary central incisors, 20 feldspathic porcelain specimens and 20 self-cure acrylic cavities filled with amalgam were divided into 2 groups bonded with Transbond XT, and Assure. After surface preparation in each group, Transbond XT composite was applied to the surfaces using silicon tubes and light-cured for 20 seconds. Then, the microshear bond strength was determined using Zwick Roell machine. The data were subjected to two-way ANOVA, Tukey’s post hoc test, Student’s t-test and the Kruskal Wallis test. Different microshear bond strengths were obtained for the bond to stainless steel brackets, amalgam and porcelain by Transbond XT and Assure resin (p<0.000). Using Assure for bonding to amalgam (7.2±1.46 vs. 10.12±4.97) and brackets (16.14±3.2 vs. 20.16±5.12; p<0.05) decreased microshear bond strength. However, Assure significantly increased the bond strength to porcelain compared to Transbond XT (28.84±6.42 vs. 22.48±3.6; p<0.01). Non-parametric Kruskal-Wallis test showed significant differences in adhesive remnant index (ARI) between the two bonding agents only in the amalgam group (p=0.029). Although the bond strength values of Assure were less than those of Transbond XT, Assure was able to create sufficient bond strength especially to porcelain.

Demand for implant supported overdentures has increased due to the problems of conventional dentures. Despite the high success rate of implants, implant failure remains a major challenge. Implant overload can cause cortical bone loss and implant failure. Using finite element analysis, this study aimed to find the best design and type of attachments causing minimum stress in the alveolar bone. The geometrical model of the mandible was produced using computed tomography (CT) data and three ITI implants were placed in the midline and the location of the first premolar teeth. All conditions were simulated using finite element software. Three bar-ball, bar and ball attachments were considered to support the overdenture. Maximum von Mises stress was calculated in the supporting bone in different overdenture designs. The results showed that the greatest amount of stress in bone was around the upper thread and the neck of the implant. The ball and the bar-ball attachments applied the most and the least amount of stress to the bone around the implant, respectively. Maximum stress was applied to the ball attachment in the bar-ball design. The maximum amount of movement was in bar-ball attachment. The bar-design decreased the stability of overdenture, as well as the stress in the peri-implant bone. Ball design increased concentration of stress in bone around the implant and increased the stability of overdenture.

An intracanal irrigant is essential for a successful root canal therapy. The aim of this study was to compare the antifungal efficacy of 5.25% sodium hypochlorite, 2% chlorhexidine gluconate and 94% carvacrol against Candida albicans in vitro. In this experimental study, after crown removal and canal preparation of 48 extracted human maxillary central incisors, they were randomly divided into 3 experimental groups of 14 teeth, plus 3 teeth as positive and 3 as negative controls. A suspension of Candida albicans (ATCC=10261) was injected into the experimental and positive control group root canals. The teeth were then incubated for 72 hours. Then, each group was rinsed with one of the irrigants for 1 minute and samples were taken from the canals and inoculated on plates. After 48 hours of incubation, the colony growth was assessed and colony forming units (CFUs) served as a measure of antifungal activity. Data were analyzed using the Kruskal Wallis test. In carvacrol, sodium hypochlorite and chlorhexidine gluconate groups, 6, 10 and 1 specimen did not show bacterial growth and the mean CFU was 86.3, 53.3 and 271.2 in the mentioned groups, respectively. Carvacrol and 5.25% sodium hypochlorite had similar antifungal efficacy against Candida albicans and this effect was significantly greater than that of 2% chlorhexidine gluconate.

To estimate the age in forensic identification, when none of the methods is satisfactory, the teeth are used. The aim of the present study was to estimate the age from pulp/tooth area ratio (AR) by digital panoramic radiography in patients referred to a radiology clinic. In this diagnostic study, digital panoramic radiographs of 120 cases were assessed. The chronological age was calculated by subtracting the date of birth from the date of radiographs and the pulp/tooth AR was calculated with "AutoCad" software. Using the regression model, the age was estimated. In this study, the role of sex was also assessed. The mean difference between the chronological and estimated age was 0.11 years in male group. The correlation coefficient was -0.180 and the correlation between age and AR was not statistically significant (p= 0.169). The mean difference between the chronological and estimated age was 0.36 years in female group. Correlation coefficient was -0.336 and the correlation between age and AR was significant (p= 0.004). Negative correlation indicates that by advanced age, pulp/tooth AR decreases. According to the results of this study, AR alone cannot be used for age estimation alone, but it can be used as combined index with other indices for this purpose.

Improving the quality of dental education significantly enhances the quality of services and promotes public health. The purpose of this study was to assess the reliability and validity of the Persian version of dental student learning education questionnaire (DSLES) and a researcher made questionnaire about interest of dental students in their field of study. A questionnaire composed of two major components was designed for this study. The first part, was a researcher made questionnaire related to students’ interest in their field of study and the second part was the Persian translation of the DSLES. Delphi approach was used for content validation. Cronbach’s Alpha and the Kappa coefficients were determined by SPSS for assessing reliability. All indicators of content validity (except for 6 items in the second part) and the inter-rater agreement were higher than %75. The Cronbach’s alpha for all subscales was higher than %75 and the Kappa for all items was higher than %73. According to the results of 375 questionnaires, Cronbach’s alpha for the first part was 79%, for the second part was 85% and for the entire questionnaire was 86%. The designed questionnaire can serve as an acceptable instrument in the Iranian educational settings.

Fine needle aspiration (FNA) cytology is a safe, reliable, minimally invasive and cost-effective technique for the diagnosis of salivary gland lesions. This study aimed to assess the accuracy, reliability and diagnostic value of FNA cytology in Iran. A total of 200 records of patients with a history of biopsy or surgical excision of salivary gland lesions along with their histological and cytological examination results were retrieved and evaluated in the Pathology Department of Amir Alam Hospital during 2007-2013. The results of cytological diagnosis were divided into 4 groups of unfavorable, benign, suspicious and malignant. The cytological results were compared with the histological data. The accuracy, sensitivity, specificity, positive predictive value and negative predictive value of FNA cytology were calculated using SPSS version 16.00. Of the specimens chosen for the study, 173 were from the parotid, 22 from the submandibular and 5 from the minor salivary glands. FNA cytological diagnosis was benign in 161 cases, suspicious for malignancy in 4 cases, and malignancy in 35 cases. Of 161 cases diagnosed as benign by FNA cytology, 25 were malignant and the frequency of false positive results was 15.5%. The accuracy, sensitivity, specificity, positive and negative predictive values of the FNA test were 82, 53, 93, 72 and 84%, respectively. A good agreement exists between the FNA results and final histopathological diagnosis of salivary gland tumors. Also, this study showed that FNA cytology has moderate accuracy and relative diagnostic value for diagnosis of salivary gland lesions.

Prevention of contamination during the procedural steps is a requisite for achieving a satisfactory composite restoration. The aim of this experimental study was to compare the shear bond strength of composite to enamel in two different decontamination procedures of uncured bonding and uncontaminated conditions. Thirty-six extracted sound human premolars and incisors were selected. Enamel of buccal surface was ground flat. The teeth were divided into 3 groups of 12 each. In the control group (1), 3M Single Bond adhesive was used according to the manufacturer’s instructions, without any contamination. In groups 2 and 3 uncured adhesive was saliva contaminated and then: (2) rinsed, dried, etched (5 seconds), rinsed, dried, adhesive was reapplied and (3) cured, dried, etched (5 seconds), rinsed, dried and adhesive was reapplied. Then composite cylinders were bonded to enamel surfaces.Finally, samples were sheared using Instron testing machine and shear bond strength data were subjected to one-way ANOVA. The mean bond strength was 16.5317 MPa in the control group, 16.2308 MPa in rinsed contaminated bonding group and 15.8025 MPa in cured contaminated bonding group. No statistically significant difference was found in the mean shear bond strength of groups 1,2 and 3 (p=0.954). Both decontamination protocols (groups 2 and 3) resulted in acceptable bond strength and both were comparable with uncontaminated condition.

Tooth colored restorations are the commonly used current approach for aesthetic problems associated with brown spots. Considering the importance of conservative dentistry, the aim of this in vitro study was to evaluate the efficacy of color correction using casein phosphopeptide amorphous calcium phosphate (CPP-ACP) and resin infiltration after using 20% carbamide peroxide for brown spots in esthetic areas. In this experimental study, 70 human teeth samples with brown spots were collected. In the first step, 20% carbamide peroxide was applied and then samples were divided into two groups to be treated with CPP-ACP or resin infiltration. Color parameters of the samples were evaluated at baseline, after bleaching, after using infiltration resin and CPP-ACP. Any color shift was measured using spectrophotometer. The results were analyzed by SPSS version 20. For statistical analysis, paired t test, independent t-test and repeated measures ANOVA were used. P value<0.05 was considered significant. After using 20% carbamide peroxide, L* and b* increased and a* decreased significantly (p<0.001). By using CPP-ACP, decreases in a* and b* were not significant (p>0.05) but L* increased significantly (p<0.001). Application of infiltration resin caused a significant decrease in a* (p<0.001); however, the decrease in L* and the increase in b* were not statistically significant (p>0.05). Comparison of the two groups showed that the degree of color shift (ΔE) in brown spots was significantly different only after bleaching (p<0.001). Repeated measures ANOVA showed that ΔE between brown spots and adjacent sound enamel did not change significantly in the two subgroups (p>0.05). The results show that for esthetically unfavorable brown spots, using 20% carbamide peroxide with CPP-ACP or resin infiltration can improve the appearance. In general, application of resin infiltration with carbamide peroxide is preferably recommended for improving translucency.

Dental staff are exposed to aerosols. Water supply of dental units has insignificant bacterial count but the exiting water in the waterlines has over 100,000 microorganisms per milliliter. Various types of microorganisms exist in the waterline of dental units. Legionella pneumophila, Pseudomonas aeruginosa and Gram-positive cocci are among the most important ones. Scaling and root planning is a dental procedure carrying a high risk of bacterial contamination. This study aimed to assess water contamination in private dental offices in Isfahan. In this descriptive study, sampling was done in 50 private offices; 10 ml samples of dental unit water were collected from each scaler and a sample from the city tap water as control. We used 3-step PCR for Legionella detection. The extracted DNA was evaluated for the presence of mip gene sequence using spectrophotometry. For detection of Pseudomonas aeruginosa, samples were cultured in Brilliant Green Bile broth. To confirm P. aeruginosa, the grown colonies were cultured in Cetrimide agar medium and presence of P. aeruginosa was re-confirmed with oxidase test. For evaluation of Gram-positive cocci, multiple smears were prepared and after Gram staining, Gram-positive specimens were cultured in blood agar medium. Data were analyzed using SPSS version 20 and reported in tables and diagrams as number and percentage. None of the control samples were positive for any bacterium. Thirty-two test samples were also negative for the understudy bacteria; but 18 offices tested positive for these bacteria. Our results shows that hazardous bacteria may be present in dental unit biofilm. Special attention must be paid to the cleanliness of water used in dental procedures.

Due to specific properties of dentin, such as tubular structure and intrinsic moisture, bond to dentin is more difficult than to enamel. The purpose of this study was to compare the shear bond strength (SBS) of composite resin to dentin using three different types of resin bonding agents and a glass ionomer-based adhesive. In this in vitro study, 72 premolar teeth without caries or restorations were selected and randomly divided into six groups of 12. The first group (I) was chosen as the control group and received no preparation of dentin surface. The remaining groups received application of Single Bond (group II), OptiBond XTR (group III), All-in-One (group IV) and GC Fuji Bond LC adhesive as pre-cure (group V) and co-cure (group VI) on dentin surface, respectively. The samples were stored for two weeks in water at room temperature and then their SBS was measured using Zwick universal testing machine with a crosshead speed of 1mm/s. Statistical data were analyzed using One-way ANOVA and Tamhane's T2. The group bonded with OptiBond XTR had the maximum SBS (24.05±9.43 MPa) and the control group showed minimum SBS (0.68±0.32 MPa). SBS of composite resin to dentin in groups V and VI bonded with GC Fuji Bond LC adhesive was significantly lower than that in groups bonded with resin bonding agents (p<0.05). Based on the results, application of GC Fuji Bond LC glass ionomer adhesive is not recommended to bond composite to dentin.