Journal of Mashhad Dental School
Year:2014 | Volume:38 | Issue:3|Papers Count:14

Introduction: Due to high viscosity, adaptation of packable composite to cavity walls is doubtful. This study investigates the effect of flowable composite liner on the dentinal bond strength of packable composite after thermal and mechanical cycling and its comparison with hybrid composites.Materials & Methods: In this experimental study, Single Bond was applied on the dentinal surface of 30 third molars. The teeth were randomly divided into three groups: In group I, P60 with Filtek Flow, in Group II, composite P60 alone, and in Group III, composite Z100 were used. After thermocycling, each group was randomly divided into two sub-groups (control and experimental) and only experimental subgroups were tested under load cycling (50 Newton, 100000 load cycles). Microtensile bond strength of all samples was measured and the failure mode was examined with a stereomicroscope. The results were statistically analyzed by Kurskal Wallis, Mann Whitney and Fisher’s Exact test.Results: Before load cycling, the mean bond strength and standard deviation of group 1 was 25.49±2.35, group 2 was 35.63±3.57 and group 3 was 30.61±5.56 MPa, which was statistically significant (P<0.05). After load cycling, the mean bond strength and standard deviation of group 1 was 24.37±1.42, group 2 was 31.36±2.63 and group 3 was 26.87±9.16 MPa. The difference was not statistically significant. The difference between control and experimental groups was not statistically significant in any of the materials.Conclusion: Flowable composite liner was not effective on the bond strength of packable composite to dentin and it was the same as hybrid composite pre and post cycling.

Introduction: Lack of information about different glass ionomer cements (GICs) in Iran’s market makes it necessary to conduct further studies about production of glass ionomer cement. The purpose of this study was preparation and characterization of glass ionomer cements nanoand microparticles and comparing their mechanical properties and in vitro bioactivity.Materials & Methods: The nanoparticles of the ceramic part of GIC were prepared using sol-gel method with particle size less than 80 nm and microparticles of the ceramic part of GIC were produced through melting method with particle size less than 70 mm. XRD, XRF, SEM and TEM examinations were used to evaluate phase structure, chemical composition and particles’ morphology. For investigating the in vitro bioactivity, samples were immersed in the simulated body fluid (SBF) for 28 days. Scanning electron microscope (SEM) was used for confirmation of the apatite layer formation on the surface of glass ionomer cements. Also, the compressive strength of the samples was determined and compared. One-way ANOVA was used for data analysis.Results: The results confirmed the production of GIC using the sol-gel and melting technique. Amorphous and glassy structure of GIC powders and their proper chemical composition were verified by characterization tests. The result of soaking in SBF showed that nGIC had higher bioactivity in comparison to mGIC. The compressive strength measurements showed that nGIC had higher compressive strength in comparison to mGIC.Conclusion: All these results confirmed higher in vitro bioactivity and compressive strength of nano glass ionomer cements compared to macro glass ionomer cements.

Introduction: Discoloration is one of the most common reasons for replacement of resin composites. The purpose of this study was to compare the color stability of three Methacrylate-based Resin Composites (Filtek Z250, Filtek Z250x, Filtek Z350xt) with Silorane-based Resin Composites (Filtek P90) after Accelerated Artificial Aging (AAA).Materials & Methods: In this in vitro study 56 composite discs were prepared (N=14). CIE L*a*b* parameters of each specimen were measured by a reflectance spectrophotometer after 24h and 384 h of AAA. Then Color change (DE) of each composite was calculated. Data were analyzed by one way ANOVA, Tukey and paired t-test at the significance level of 0.05.Results: DE values of Filtek Z250, Filtek Z250x, Filtek Z350xt and Filtek P90 were 7.77, 5.86, 8.95 and 8, respectively. One way ANOVA demonstrated a significant difference between DE values of composites (P˂0.001). Tukey’s test revealed that DE value of Filtek Z250xt was significantly lower than those of other composites (P˂0.05).Conclusion: Silorane and methacrylate based composites showed a color change more than the clinically acceptable level (DE˃3.3) after AAA. Filtek Z250xt showed the lowest color change and other composites showed relatively similar color change.

Introduction: Salivary gland tumors are heterogeneous neoplasms with relatively low incidence. Due to uncertainty regarding the role of angiogenesis in malignant salivary gland tumors, the aim of present study was assessment of blood vessel density in two malignant salivary gland tumors.Materials and Methods: In this descriptive-analytical study, a total of 40 paraffin blocks of adenoid cystic carcinoma and mucoepidermoid carcinoma were removed. Immunohistochemical staining was done for evaluation of blood vessel density with CD34. Tumors were divided into two groups of low and high malignancy. Clinical data of patients were extracted from the patients’ files and vascular density and its association with clinicopathological factors was evaluated by Kruskal-Wallis, Mann Whitney, Wilcaxson and X2 (Chi-Square) test.Results: The means total density of blood vessels, intra tumoral and peri tumoral area in adenoid cystic carcinoma were 16.6±7.4, 11.9±5.9 and 4.8±2.3 and in mucoepidermoid carcinoma were 19.11±6.44, 14.47±5.63 and 4.63±1.73, respectively. Significant differences between mean total density of blood vessels (P=0. 279), central (P=0.171) and peripheral (P=0.734) in two lesions were observed. There was no significant difference in density of blood vessels between high and low grade malignant salivary gland tumors (P=0.21). No significant correlation was seen between microvessel density and age, sex and location.Conclusion: Higher grade malignancy and clinical parameters did not affect the blood vessel density. There were higher microvessel densities in central area than peripheral area of tumor.

Introduction: different effects of disinfectants in vitro and in vivo conditions have been attributed to the inhibitory effect of dentin. The purpose of this study was in vitro evaluation of inhibitory effect of dentin on the antimicrobial property of Carvacrol and sodium hypochlorite on euterococcus faecalis.Materials & Methods: In this experimental study, an enterococcus faecalis suspension of 1.5´108 cells per militer was prepared. Fifty microliter of antimicrobial solution (sodium hypochlorite 2.5% and 1% and Carvacrol 0.6% and 0.3%) were incubated at 37oC with 28 mg dentin component (dentine powder, organic dentin component, mineral dentin component) in 50 microliter water for 1 h before adding 50 microliter of the bacterial suspension. Ten microliter samples for bacterial culturing were taken from the suspension 5min, 1 and 24 h after adding the bacteria. Serial 10-fold dilutions were made of the samples and 10 microliter of dilutions was cultured on BHI plates for 24 h at 37oC. After incubation period, colonies were counted by one person by visual observation method. Data were analyzed by Kruskal-Wallis and Mann-Withney tests (a=0.05).Results: Dentin components, antimicrobial solutions and time, all three affected the final results. The inhibitory effect of dentin components on antimicrobial property of Carvacrol was significantly greater than Sodium hypochlorite (P<0.001).Conclusion: Antimicrobial effect of sodium hypochlorite is preserved at presence of dentin, but dentin inhibitory effect on Carvacrol antimicrobial property is observed after 1 h.

Introduction: MTA Fillapex and iRoot SP are two new sealers which have very similar characters to MTA. The purpose of this study was to assess and compare apical seal of the obturated canals with the iRoot SP, MTA Fillapex and AH-Plus sealers.Materials & Methods: Seventy two freshly extracted single root canal human premolars were selected for this study. The canals were instrumented with hand files using step back technique. Six specimens were assigned for positive control and six for negative control groups. The rest of the specimens were randomly divided into three groups of 20 and obturated with gutta percha and one of the aforementioned sealers. Microleakage in all groups was assessed, 2 weeks and 3 months after obturation of canals, by means of fluid filtration. The data were analyzed using repeated measurement and post-hoc Tukey test. The level of significance was set at P<0.05.Result: In none of the assessment intervals, there was a significant difference between AH-plus and MTA Fillapex. iRoot SP had less microleakage compared to other groups significantly (P<0.001). Microleakage assessments revealed no significant differences between 2 weeks and three months in all groups.Conclusion: iRoot SP sealer had significantly less microleakage compared to MTA Fillapex and AH-Plus.

Introduction: Since there are no precise reports about maxillofacial fractures in Mashhad, we conducted a study to assess the pattern of maxillofacial fractures at Shahid Kamyab Centre during 17 months in Mashhad.Materials & Methods: In this cross sectional study, 495 patients of Mashhad Shahid Kamyab trauma center with maxillofacial trauma during 17 months were evaluated. Age, sex, site of fracture, etiology and treatment were recorded by observation and questions. Data were by analyzed with software SPSS 11.5.Result: Eighty point two percent of all 495 patients were male and 20% were female. The most frequent age was 21-30 years and the most frequent causes of maxillofacial fractures were motor vehicle accidents (75.4%) and assaults (15.2%). The average number of fractures was 1.8 and the most frequent site of fractures were mandible (27.3%) and zygoma (20.9%). Open reduction had been done for 2.6% of the cases.Conclusion: The main cause of maxillofacial fractures is motor vehicle accident, which necessitates better promotion of traffic rules and safety.

Introduction: Dental caries is a common and preventable disease in children. The goal of this study was to evaluate the risk factors of dental caries in children under 6-years-old supported by welfare organization of Mashhad in 2012.Material & Methods: A cross sectional study was carried out on 143 children under 6-years-old (63 female, 80 male) from all sub-centers of Mashhad welfare organization. Prevalence and severity of dental caries (dmft) was evaluated and a caries risk factors questionnaire was completed. The results were statistically analyzed using Chi-Square and Mann-Withney tests.Results: Caries prevalence was 81.1% and the mean dmft was 6.1±5.4, in which decay (d) was the major component. Age, complications during pregnancy, dental plaque, white spot, deep fissures, initial caries of occlusal fissures, treatment within the past 2 years, dental extraction due to caries and the childs mother or caregivers DMFT were factors correlated with dental caries in children.Conclusion: Caries prevalence was high among the study population, which could be partly due to inadequate attention of the children's caregivers and their lack of knowledge regarding oral hygiene.

Introduction: The aim of this study was to evaluate the clinical and radiographic outcomes of Propolis in pulpotomized primary molars in comparison with Formocresol.Materials & Methods: In this clinical trial, 26 lower second primary molars of thirteen children were treated by conventional pulpotomy technique. The teeth were randomly assigned to Propolis (experimental) and Formocresol (control) groups in each patient (split mouth).Following removal of the coronal pulp and haemostasis, the pulp stumps were covered with Propolis in the experimental group and then resin-modified glass ionomer cement was applied over the gel. In the control group, Formocresol (FC) was placed with a cotton pellet over the pulp stumps and then reinforced zinc oxide eugenol cement was applied in pulp chamber. Finally, the teeth of both groups were restored with stainless steel crowns the data were analyzed using Mc Nemar test (a=0.05).Results: All patients developed failure clinically within two months of treatment. The radiographic evaluation revealed furcation involvement and extensive radicular radiolucency in molars treated with Propolis.Conclusion: The present study showed the failure of Propolis in pulpotomized primary molars; therefore, it could not be used as a safe medicament for pulpotomy in human primary molars.

Introduction: Juvenile ossifying fibroma (JOF) is a rare benign but locally invasive tumor with high recurrence potentials. It is fibro-osseous neoplasm of the jaw characterized by substitution of normal bone by fibrous tissues and newly formed calcified products such as bone, cementum or both. Juvenile ossifying fibroma is a well-demarcated lesion that differentiates it from fibrous dysplasia. This tumor may be confused with malignant condition due to rapid growth and osteolytic nature. It occurs in children and young adults. We report a 12 year old girl with a painful swelling in the right mandibular body and inferior border of the mandible referred to Mashhad Dental School in November 2013. Histological examination of incisional biopsy showed JOF. Treatment included block resection. Recurrence had not been observed in follow up from surgery up to the time of this report.Conclusion: JOF is a rare fibro-osseous neoplasm found in the young age group, which is considered locally more aggressive than the conventional form and spreads quickly. Therefore, it is important to diagnose the lesion early and correlate all available clinical, radiological, CT scan and histologic data for better management.