Search

Objective: Attachments are used for connections between overdentures and dental implants. The maintenance of attachment components plays an important role in optimal clinical service of overdentures. This study aimed to compare the effects of overdenture insertion by hand pressure versus placement by clenching the jaws on the retention and diameter of resilient attachments.Methods: Thirty patients with mandibular overdentures participated in this study. First, the patients were instructed to insert the overdentures with hand pressure. After 6 months, patients were recalled, the nylon matrix components of the attachments were replaced, and the patients were instructed to place the overdentures by clenching for the next 6 months. The retention and internal diameter of matrices were measured at baseline and at 6 and 12 months later. A universal testing machine was used to measure the residual retention, and a coordinate measuring machine was used to assess the matrix diameter. The retention loss and changes in matrix diameter were compared between the two techniques, using paired samples t-test.Results: The results showed that retention loss was lower in the hand placement method than in the clenching method (P

Introduction: In case of severe destruction or total coronal loss of tooth structure the retention of the core is achieved by embedding a post into the root canal. There are different prefabricated posts for buildup of coronal tooth structure. There is no same opinion about which post is more effective for root canal treatment (RCT) tooth. The aim of this study is to determine the effect of post material on the stress distribution of RCT maxillary canine by finite element analysis (FEA). Methods: A canine tooth was mounted inside a resin. A 3D scan of the mounted tooth was prepared by cone-beam computed tomography (CBCT) method. The Mimics Medical and Solidworks software was applied to provide an appropriate 3D model of the canine tooth. Post core crown restorations with three different types of prefabricated post, glass fiber, zirconia, and titanium, were considered for the restoration. An oblique load of 100 N was applied on the cusp and then FEA was performed by ABAQUS software. Results: The results of FEA showed that in all models the maximum principal stress occurred at the crest area. The stress decreased in dentin and increased in the post and cement interface by increasing of post elastic modulus. Conclusion: In according to FEA results it could be deducted that the post stresses are increased, by increasing of post elastic modulus, as well as the post material has a small contribution to the stress of the cervical area.

Introduction: Amalgam, which can be applied with or without dowel, is one of the commonly used restorative materials for core restoration in pulpless teeth. The current study aimed to compare the shear strength of amalgam cores with and without dowel. Methods: A total number of 20 recently extracted mandibular premolars were assigned to two groups of 10 equal specimens, including group I: dowel amalgam restored with prefabricated dowel and amalgam core and group II: post-amalgam restored with amalgam as a post and core. All Specimens were stored at humidity and room temperature prior to testing. Each specimen was carefully placed in a special jig at a 90-degree angle to the axis of teeth and subjected to a load that was recorded in kgf on a Zwick/material testing machine at a crosshead speed of 0.5 mm/min until failure. Independent T-test was used to compare the results. Results: Based on the obtained results, the mean shear strengths were reported as 37.7±10.49 and 16.8±6.37 kgf for dowel amalgam and post-amalgam, respectively. There was a statistically significant difference between the two groups (PConclusions: The obtained results demonstrated a significant difference between the two groups. Accordingly, the use of dowel with amalgam to restore pulpless teeth has higher compressive strength, as compared to the use of post-amalgam

Background and Aims: Candida is an opportunistic pathogen that causes illness in people with a defective or weakened condition. Infectious diseases (periodontal diseases) are inflammatory and malignant inflammation of the dental-gum complex, in which the growth of biofilms caused by Candida glabrata, Parapseilosis and Tropikalis is less than Candida albicans. Brown algae Sargasum is more compatible with human medicines due to having a natural origin than chemical drugs and has less side effects. The aim of the present study was to investigate the molecular characteristics of Candida species isolated from periodontal infections and the effect of Sargassum glaucescens extract on biofilm gene expression using Real-Time-PCR. Materials and Methods: Oral samples of periodontal infection were collected from the referred patients. To isolate the candidate species, the specimens were cultured on a Sabouraud dextrose agar containing chloramphenicol (SDAc). The extracted DNA was extracted from colonies grown from Kit and Glass pearl. Grown chickens were identified by specific primers by PCR-RFLP method. In order to detect the expression of als genes in Candida isolates, RNA extraction was performed using Phenol-Chloroform and Pearl glass, and the CLSI-M27-A2 method was used to evaluate the effect of Sargasum glaucescens extract of algae. Results: The results showed that the expression of als gene in periodontal infection is higher than other genes. Another role is als in the formation of Candida albicans biofilm. The minimum inhibitory concentration of fungal growth was 256 μg/ml by algae extract. Sargasum glaucescens reduced the expression of als gene expression by about 62% in the sample. Conclusion: Sargasum glaucescens algae possesses specific pharmacological properties and antimicrobial and antimicrobial effects. The results of the study using Real Time PCR showed that expression of als gene in isolated studied with Sargasum algae extract was lower than untreated isolates. Thus, this indicated the positive role of treatment by sargasum glaucescens extract in reducing the expression of biofilm gene in isolates.

"People Involvement" In ideologies and systems related to democracy, especially religious democracy, is the common concept which creates a visible difference between democrat systems and non-democrat systems. People Involvement as an important concept is a justification for democrat and religious democrat states and from this perspective, it is possible to create different expression regarding to democracy. According to this article, there are two main perspectives related to justification of people involvement. In this case, there are two patterns; "Single-dimensional" legitimation pattern and "Multi-dimensional" legitimation pattern. The first one oversees one aspect of government like the competence of the ruler or process of acquiring power and enforcing it, and the second one oversees all aspects of the government like conclusions and effectiveness in addition to the previous case. In this article, G.T. methodology has been used. The Ayatollah Khamenei's position is considered as the second group where legitimation is a multi-dimensional pattern and oversees four dimensions of government.

Background: Resin cements are widely used for cementation of FRC posts, but their bond strength can be influenced by cement type and cementation technique. The aim of this study was to determine the effect of type of resin cement and cementation technique on the bond strength of fiber posts. Methods: Forty five extracted mandibular premolars with a minimum root length of 14 mm were cut from 1 mm above the CEJ and root canal therapy was performed on them. Based on the type of cement, they were randomly divided into three groups: 1- Permacem, 2- Totalcem and 3- Breeze. Each group was divided into three subgroups based on cementation technique: 1- paper point, 2- lentulo and 3- tip. The push out test was carried out on 2-mm sections of cervical, medial and apical areas in the universal testing machine with a speed of 1 mm/min. Results: The highest mean of bond strength among cements was in Breeze cement, but this finding was not statistically significant. In terms of different cementation techniques, the highest strength was found for lentulo technique. The bond strength showed no significant difference at different sections of root based on the type of cement and cementation technique. Conclusion: Cement type has no significant effect on bond strength. The use of lentulo enhances bond strength significantly. No difference was observed in bond strength of different sections of the root in different cements. The greatest fracture mode was adhesive fracture between post and cement.

Introduction: In post-core crown restorations, the use of prefabricated composite posts concentrate stress at the cervical region and the use of metal posts (prefabricated and customized posts) concentrates stress at the interfaces. Fiber reinforced composite posts (FRCs) with oval cross-section (oval posts) were proposed for post-core crown restorations to reduce the stress levels at the cervical region. The aim of the present study was to investigate the impact of oval cross-section composite posts on stress distribution of premolar with oval-shaped canal by using three-dimensional (3D) finite element analysis. Materials and Methods: An extracted premolar tooth was mounted, sectioned, and photographed to create a 3D model. The surrounding tissues of the tooth, periodontal ligament, as well as cortical and trabecular bones were modeled. Seven taper posts with two different cross-section geometries (circular and oval shapes) were modeled, as well. Then, the effect of post geometry, post material (carbon fiber and fiberglass), and cement material were investigated by 3D finite element analysis and the stress distribution results were compared. Results: In all the models, the highest stress levels of the dentin were accumulated at the coronal third of the root, and the highest stress levels at the bonding layers were accumulated at the cervical margin. Narrow circular posts induced the highest stress levels, whereas the stress levels were reduced by using thick oval posts. Application of elastic cement reduces the stress at the bonding layers but increases stress at the dentin. Conclusion: Finite element analysis showed that prefabricated oval posts are superior to traditional circular ones. The use of cement with low elastic modulus reduces the risk of debonding but raises the risk of root fracture.

Background and Aim: Several methods are available for intraoral repair of chipped porcelain restorations by composite resin. Also, there is still controversy regarding the best method of porcelain repair in terms of bond strength and cost effectiveness. This study aimed to compare three methods of porcelain surface treatment on shear bond strength (SBS) of composite to porcelain. Materials and Methods: This in vitro, experimental study was conducted on 30 porcelain blocks with a metal base in three groups. In group 1, porcelain surface was etched with hydrofluoric (HF) acid and silanized. After the application of bonding agent, several composite increments with 2mm thickness were applied on the porcelain surface. In group 2, porcelain surface was sandblasted with 50µaluminum oxide particles, etched and silanized. In group 3, grooves with 2mm length and 0.5 mm depth were created on the porcelain surface. The surface was then etched and silanized. Bonding agent and composite were then applied. The samples were then mounted in acrylic resin, stored in water for one week and subjected to thermocycling. The SBS was then measured using a universal testing machine. The SBS data were compared among the three groups using one-way ANOVA. Results: The mean SBS was 9.13±6.09, 12.71±9.82 and 11.44±7.37 MPa in groups 1-3, respectively. No significant difference in bond strength was noted among the three groups (P>0.05). Conclusion: No significant difference exists among the three surface treatment methods evaluated in this study in terms of SBS of composite to porcelain.

Background & Objective: Classrooms are suitable environment for transferring teachers experiences to students and gaining a better understanding of educational contents The students absence from theoretical classes has been one of the increasing and most important educational problems in medical universities in recent years This study was performed to determine factors effective on theoretical class attendance according to the point of view of dentistry students of Kerman University of Medical Sciences Iran in 2012 Methods: This crosssectional study was conducted on 150 students of the School of Dentistry Kerman University of Medical Sciences in 2012 Data collection tool was a questionnaire consisting of 2 parts: demographic characteristics and effective factors on theoretical class attendance questionnaire The questionnaire consisted of 20 questions scored based on a 5point Likert scale from very effective to ineffective and scores ranging from 0 to 80 Higher scores indicated more effective factors Data were analyzed by SPSS software through linear regression analysis Values of P < 005 were considered significant Results: Of the 150 participants 587% were female 833% were single and 613% were native students The mean age of the participants was 207 ± 17 years The mean score of the students was 5824 ± 959 A significant statistical relationship was observed between area of residence year of education and sex of students and mean score of questionnaire Among factors effective on theoretical class attendance the highest score belonged to appropriate teaching method teachers scientific proficiency students interest in the related topic However taking part in the class as a duty and active involvement of students had the lowest scores Conclusion: The findings of the present study showed that attendance in classes is affected by factors related to both teachers and students However appropriate teaching method teachers scientific proficiency and students interest in the related topic are the main factors which determine students attendance in the classes

Introduction: Cone beam computed tomography (CBCT) is a new method that is able to provide three-dimensional images in radiology and is useful for dentomaxillofacial imaging. This study aimed to investigate the cases administrated CBCT by dentists of Kerman (2015 year). Methods: This cross-sectional study was conducted on dentists in Kerman. The data were gathered using standard research questionnaires containing 20 questions about the CBCT prescription and 10-question on diagnostic value of CBCT with intraoral radiographs and other information regarding the participants (age, sex, job, participate in the retraining of radiology, retraining courses, radiation protection). Data was analyzed by T test, regression and SPSS 18. Results: Among 182 participants, 107 (52.26%) were male and the rest were female with an average age of 37.16±8.93 years. The mean score of the questions of CBCT was 75.75±3.43, and the diagnostic value of the study was 16.17±2.15. The value of questions was statistically significant between general practitioners and specialists (P=0.01). There was no difference between men and women in the administration of CBCT. The difference between male and female dentists for diagnostic value of CBCT and other X-ray was statistically significant (P=0.029). Between continuing medical education courses, retraining radiology, radiation protection programs, CBCT and diagnostic value with other radiological statistically significant correlation was observed. Conclusion: The results of this study showed that knowledge of dentists in the administration of CBCT and its diagnostic value with other X-rays was satisfactory.

Background & Objective: Dentistry is a stressful job and dental students are exposed to educational and environmental stresses The aim of this study was to determine the stress level in dental students Methods: This crosssectional study was conducted on students of School of Dentistry Kerman University of Medical Sciences Iran Data were collected by Depression Anxiety and Stress Scales (DASS21) standard questionnaire and analyzed by linear regression and ttest Results: 326% of students had moderate and 43% had severe stress There was no significant differences between sex academic year mean of scores and stress level Married students had more stress (P = 0037) Students staying with their parents had low stress level (P = 0047) In 66% of students the university issues were stressor Conclusion: Based on the result of this study stress level among dental students is fairly high greater attention to this issue is recommended

BACKGROUND AND AIM: The number of patients who need prosthetic treatments has increased. Efficient and regular procedures for cleaning removable dentures are important for maintaining good oral health. The aim of this study was to analyze the oral and prostheses care habits of removable denture users, who attended the clinics of Kerman, Iran. METHODS: This cross-sectional study was carried out on 350 patients, who attended the clinics of Kerman and were chosen by the multistage sampling method. Data were obtained from a checklist consisting of demographic characteristics (age, sex, educational level, kind of prosthesis, age of prosthesis, self-report of halitosis, and smoking status), denture hygiene habits, denture-wearing behavior, and cleanliness of denture by examiner. Data was analyzed using chi-squared test (P < 0.05). RESULTS: The mean age of patients was 58.52 ± 10.78 years, 103 (29.4%) were male and 247 (70.6%) were female. The results showed that 78.6% had complete denture and 12.7% reported halitosis, 55.1% used their denture at night, and 36.4% had poor denture hygiene. Brushing was the most used cleaning method by the patients (36.5%). 60.4% reported never having been instructed by their dentists as to how to clean their dentures. 58.6% had been using the same denture for more than 5 years. There was a significant correlation between the kind of denture, and denture hygiene and education level. CONCLUSION: According to the results of the present study denture hygiene was not favorable. Therefore, dentists should instruct the patients on cleaning their denture in order to prevent denture–induced lesions.

Statement of the Problem: Understanding about impression materials, their properties, uses and manipulation can guide operators towards having more successful restorations. Purpose: The aim of this in vitro study was to compare the accuracy of a condensation silicone impression material, Optosil, and an addition poly siloxane impression material, Elite- HD. Materials and Method: A laboratory model with two metallic dies was used to make impression. A horizontal notch on one of the two dies simulated an undercut. Ten impressions were made by each impression material by the putty-wash technique. After pouring impressions with velmix die stone, a total of 20 stone casts were made from both materials. Measurements of casts were compared with the master model. Statistical analyses were performed using t-test. Result: This results of this study showed that the height of die without undercut decreased in both groups. Also the height above the undercut decreased in both groups, which was more obvious in Elite-HD group than Optosil group. The distance between dies increased in both groups, with higher figures for Elite- HD. So, Optosil is a more accurate material for registering inter-abutment distance than Elite-HD. The diameter of die under the undercut decreased in Optosil group and was similar to the master model in Elite-HD. Statistical analysis showed significant differences between these two groups in the distance between abutments (p=0.001), the diameter of die under the undercut (p=0.014) and the height of die above undercut(p=0.057). Conclusion: Optosil is more accurate in registering inter-abutment distance than Elite-HD, so Optosil is preferred for fixed partial denture impressions. Since Elite-HD showed more accuracy in C measurements than Optosil, it is preferred for single crown impressions. [ABSTRACT FROM AUTHOR]