The Effect of Acidic pH on Microleakage of Mineral Trioxide Aggregate and Calcium-Enriched Mixture Apical Plugs

Introduction: The purpose of this laboratory study was to evaluate the effect of acidic pH on the sealing ability of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA) apical plugs. Methods and Materials: Seventy single-rooted human maxillary anterior teeth were recruited. The teeth were randomly divided into 4 experimental groups (n=15), and 1 negative and 1 positive control groups of 5. The root canals were cleaned and shaped and the terminal 3 mm of the roots were resected. Then MTA and CEM cement plugs were condensed in apical region with 3 mm thicknesses. The samples were exposed to pH values of 5.5 and 7.4. Leakage was evaluated by the fluid filtration technique at 1, 7, 14, 30 day intervals. Data were analyzed by the repeated measures MANOVA, one-way ANOVA and MANOVA/Bonferroni test. Results: Acidic pH significantly reduced the sealing ability of MTA after 1, 14 and 30 days (P<0.05). The rate of microleakage in CEM cement samples in acidic pH was significantly greater than that in neutral pH in day 30 (P<0.05). There was no significant difference between the sealing property of MTA and CEM cement at both pH levels (P>0.05). Conclusion: It can be concluded that the CEM cement exhibited similar sealing ability as MTA at both pH levels. In addition, an acidic pH environment reduced the sealing ability of MTA and CEM cement after 30 days.

The Effect of Intracanal Medicaments on Microleakage of Mineral Trioxide Aggregate Apical Plugs

Introduction: The purpose of this in vitro study was to evaluate the effect of calcium hydroxide, double and triple antibiotic paste on the sealing ability of mineral trioxide aggregate (MTA) apical plugs. Methods and Materials: A total of 90 extracted teeth with single canals were prepared and randomly divided into four experimental groups (n=20). Intra-canal medicaments were applied for 3 weeks. MTA was placed through the access opening and condensed to the apical area and then fluid filtration technique was utilized to evaluate sealing ability after 1, 7, 14 and 30 days. Results: Triple antibiotic paste significantly reduced the sealing ability of MTA plug compared with double antibiotic paste (P=0.024) and normal saline (P=0.04) groups on day 1. The sealing ability was not different on days 14 and 30 between experimental groups (P>0.05). Conclusion: All medicaments can be used without any long term effect on microleakage.Keywords: Calcium Hydroxide; Double Antibiotic Paste; Endodontic Regeneration; Microleakage; Triple Antibiotic Past

IP2P K-means: an efficient method for data clustering on sensor networks

Many wireless sensor network applications require data gathering as the most important parts of their operations. There are increasing demands for innovative methods to improve energy efficiency and to prolong the network lifetime. Clustering is considered as an efficient topology control methods in wireless sensor networks, which can increase network scalability and lifetime. This paper presents a method, IP2P K-means – Improved P2P K-means, which uses efficient leveling in clustering approach, reduces false labeling and restricts the necessary communication among various sensors, which obviously saves more energy. The proposed method is examined in Network Simulator Ver.2 (NS2) and the preliminary results show that the algorithm works effectively and relatively more precisely

Histological Evaluation of Periapical Tissues after Root Canal Treatment with or without Coronal Seal in Dogs for Six Months

Introduction: Preventing recontamination of the obturated root canal is important for successful root canal treatment (RCT). The main purpose of this study was assessing the histological health of periradicular tissue in obturated root canals with or without coronal seal between two and six months. Methods and Materials: Sixty roots from five dogs with vital pulps were randomly assigned to one of the following five groups (n=12): Group 1, RCT and six months oral exposure; Group 2, RCT and immediate amalgam restoration; Group 3, RCT and amalgam restoration after two months exposure to the oral cavity; Group 4, RCT and amalgam restoration after four months exposure to the oral cavity; Group 5, RCT with two months exposure to oral cavity. The teeth were prepared and filled with gutta-percha and sealer using lateral condensation technique. Two intact root canals of each animal were regarded as the negative control group (n=10), and the two root canals exposed to the oral cavity constituted the positive one (n=10). After six months the animals were euthanized. The upper and lower jaws were removed and submitted for histological processing. Longitudinal sections were obtained from each root. After staining the sections, periradicular regions were examined histologically under light microscope. The Kruskal-Wallis and Mann-Whitney tests was used to analyze the data (P<0.05). Results: The results showed a significant difference between all groups (P<0.05). The negative control group was free of any inflammation. Two-by-two comparison revealed that the positive control group, Group 1 and Group 4 displayed the most intense inflammation. Groups 2, 3 and 5 showed similar results without developing any significant inflammation. Conclusion: Based upon the findings of this animal study, it can be recommended that the obturated root canals which are exposed to oral cavity for around four months or more should be retreated before crown restoration

Reflecting on Obstacles and Solutions to Improve Health and Hygiene in Primary Schools from 1925 to 1941 A Case Study: Exposure to Trachoma Disease

The transformation of the public and individual health system from 1925 to 1941 was known as one of the pillars of the development and acceleration of the modernization process in Iran. Despite this expansion, public health and collective health, especially in schools, found a close connection with the underdevelopment of the country. Trachoma disease was one of the most common and contagious diseases among elementary school students, and the government tried to take some measures to deal with it, such as spreading public awareness, creating a skilled workforce through the training of teachers and school staff, and applying comprehensive monitoring of students’ health in the family and school. Despite these measures, there were challenges, such as a lack of medicine, a lack of skilled workforce, and financial problems that negatively affected the quality of the government’s actions. This research raises the central question: How did trachoma disease in schools become a serious issue for the government? The hypothesis is that although the government succeeded in dealing with Trachoma in primary schools, this process was gradual, slow, and temporary due to the underdevelopment of the country’s infrastructure

Synergistic Antimicrobial Efficacy of 2% Chlorhexidine and 3% Hydrogen Peroxide for Infected Root Canals of Extracted Human Teeth: An Ex-Vivo Study

Background and Aim: An endodontic irrigation solution with low toxicity and high an-timicrobial activity is required in the process of endodontic treatment. Using a combina-tion of intracanal irrigants is one solution to achieve this goal. The aim of this study was to evaluate the synergistic antimicrobial efficacy of chlorhexidine and hydrogen peroxide against bacteria in the infected extracted human root canals. Materials and Methods: Forty-two teeth with periapical lesions were chosen for this study. The teeth were extracted and preserved in normal saline at 37°C for less than 24 hours. Canals were prepared with nickel titanium rotary files (S1 to F3) and irrigated with 10cc of the respective irrigants (group 1:14 teeth irrigated with 3% hydrogen peroxide group 2: 14 teeth irrigated with 2% chlorhexidine and group 3: 14 teeth irrigated with a combination of 3% hydrogen peroxide and 2% chlorhexidine). Samples were obtained with paper cones before and after root canal preparation (S1, S2) and transferred to a mi-crobiology lab for colony counting. Data were analyzed using the Kruskal-Wallis and Mann-Whitney tests. Results: The results showed that all the understudy irrigants significantly decreased the bacterial colony count. A combination of chlorhexidine and hydrogen peroxide was sig-nificantly more effective than hydrogen peroxide. Conclusion: Chlorhexidine is an effective irrigant with high antimicrobial activity but its antimicrobial efficacy does not significantly increase in combination with hydrogen per-oxide

Prevalence of malocclusion among Iranian children: A systematic review and meta-analysis

Background: The high prevalence of malocclusion is a public health problem in the world and the third priority in oral care. Numerous primary studies have presented reports on the prevalence of malocclusion among Iranian children. In combination, the results of these studies using meta-analysis are highly valuable for health policy-making. Similarly, this study aimed at determining the prevalence of different types of malocclusion among Iranian children. Materials and Methods: Using relevant keywords, national and international databases were explored. After narrowing down the search strategy and leaving out the duplicates, the remaining articles were screened based on titles and abstracts. To increase search sensitivity, reference lists of the papers were examined. To identify unpublished articles and documentations, a set of negotiations were done with the people involved and research centers. Finally, the heterogeneity index between the studies was determined using Cochran (Q) and I2 tests. According to the results of heterogeneity, the random effects model was used to estimate the prevalence of malocclusion in Iran. Results: In total, 25 articles were included in the meta-analysis process. The prevalence of dental malocclusion was estimated in 28,693 Iranian children aged 3-18 years. The total prevalence of Class I, II, and III malocclusion was 54.6% (46.5-62.7), 24.7% (20.8-28.7), and 6.01% (4-7.1), respectively. The prevalence of Class I, II, and III malocclusion was 44.6% (32.9-56.2), 21.5% (18.01-25.1), and 4.5% (3.2-5.9) in boys and 48.8% (36.8-60.8), 21.5% (16.9-25.1), and 5.5% (3.9-7.1) in girls, respectively. Conclusion: This study showed a high prevalence of malocclusion among Iranian children. Also, the results indicated that the prevalence is higher in girls

NUMERICAL INVESTIGATION OF IRRIGANT PENETRATION INTO DENTINAL MICROTUBULES

ABSTRACT Root canal irrigation is an important procedure in endodontic treatment. After mechanical preparation of root canal, NaOCl, which is the most common antibacterial irrigant, is inserted by special needles. This work helps to remove bacteria and debris and dissolves the organic tissues in the root canal. In the vicinity of the main root canal, there are a large number of microchannels attached to its wall named "dentinal tubules". The success of irragation depends on the penetration of irrigant in these tubules, which results in killing the bacteria and preventing complexities after root canal therapy. There is rather limited earlier research on modeling of dentinal tubules. Nevertheless, it has been shown that the flow rate, insertion depth and needle types affect the flow pattern in the root canal. The concentration difference between inserted irrigant and the liquid filling the tubules is the main driving force for penetration. Diffusion of irrigant, however, is a time dependent process and should be analyzed as an unsteady problem. In prior studies, the geometry was considered as cylinders with a constant diameter of 2.5μm and the effect of tapering was neglected. In reality the diameter varies from about 2.5μm near the pulp to about 1.5μm at the distance of 1 mm from the pulp. In the present study, a more detailed and exact model of dentinal tubules geometry was considered. The computational fluid dynamics (CFD) is used for the modeling of flow and diffusion of irrigant as a function of time. The unsteady and 3D continuity and Navier-Stokes equations as well as a scalar transport equation are solved and the flow field and the concentration of antibacterial irrigant were evaluated. The simulation results were compared to the earlier works. It was shown that the use of the correct detailed geometry of tubules led to noticeable differences compared to those found for the idealized model