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.

Designing a customized clinical practice guideline regarding antibiotic prophylaxis for Iranian general dentists.

BACKGROUND: Clinical practice guidelines produced by developed countries seemed to be not completely feasible for developing countries due to their different local context. In this study, we designed a customized guideline about antibiotic prophylaxis before dental procedures for Iranian general dentists. METHODS: This study was conducted of two parts, including a qualitative part and a cross-sectional analytic part. A multidisciplinary team searched for related guidelines and other documents, selected the most updated and high quality ones, customized their recommendations based on available antibiotics in Iran, prepared a draft adapted guideline and summarized its recommendations in 3 flowcharts. An expert panel (20 specialists of four Iranian dental universities) participated in a consensus process, afterwards to determine the relevance and clarity of the flowcharts and their items. Then the Content Validity Indices (CVIs) were calculated and any items with CVI higher than 0.79 remained. RESULTS: The adapted recommendations were summarized in flowcharts A to C. Two separate groups of patients who need antibiotic prophylaxis were presented in flowchart A; including those with high risk for distant-site infection (infective endocarditis and prosthetic joint infection) and those at risk for poor healing and orofacial infection (due to impaired immunologic function). Flowcharts B and C described antibiotic regimen and also the dental procedures where antibiotic prophylaxis was needed for mentioned groups. The content validity indices and the percentages of agreement between the expert panel members were considerably high. CONCLUSIONS: A localized, clear and straight forward guideline that addresses all groups of dental patients who need antibiotic prophylaxis has been produced for Iranian general dentists.

Numerical and analytical investigation of irrigant penetration into dentinal microtubules.

Irrigation is one of the most important steps in root canal therapy. Sodium hypochlorite is inserted into the root canal to eliminate bacteria and dissolve necrotic tissue. Dentinal tubules are micrometer sized channels along the dentin thickness. An irrigant should have the ability to penetrate into these tubules to remove bacteria residing in them. The difference between the concentrations of the inserted irrigant and the dentinal tubule fluid is the main factor of penetration. This study attempts to model dentinal tubules with precise dimensions and to study the time dependent irrigant penetration into them by using Computational Fluid Dynamics (CFD). The effects of needle type and position in the dentinal tubule were also considered. The results showed that concentration distribution would be different when the tubule was modeled as a frustum compared to the cylindrical shape tubule. Dentinal tubule curvature, however, did not have a noticeable effect in irrigant penetration. It was also concluded that when the needle working length is 3 mm, concentration can be considered constant at the tubule's entrance for tubules located at more than 1 mm from the apex. Moreover, by irrigating the root canal with a side-vented needle instead of an open-ended one, the concentration would be less for the tubules located in the apex region. Analytical solutions for different cases were also obtained, and their predictions were found to be in good agreement with the numerical results. Therefore, the presented analytical solutions can be directly used to obtain irrigant concentration in tubules with no need for additional computer simulations.

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.

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.

The Effects of Alkaline pH on Microleakage of Mineral Trioxide Aggregate and Calcium Enriched Mixture Apical Plugs.

STATEMENT OF THE PROBLEM: Alkaline pH can affect the physical and chemical properties and sealing ability of apical plug material. Calcium hydroxide is used as an intracanal medication to complete disinfection of root canals. It raises the pH of environment to alkaline value. PURPOSE: The aim of this in vitro study was to evaluate and compare the effect of alkaline pH on the sealing ability of calcium-enriched mixture (CEM) cement and mineral trioxide aggregate (MTA) apical plugs. MATERIALS AND METHOD: Seventy single-rooted human maxillary anterior teeth were randomly divided to two experimental groups for Angelus MTA and CEM cement (n=30) and two control groups (n=5). Each group was divided into two subgroups of 15 for neutral and alkaline pH, and 1 negative and 1 positive control groups of 5. The root canals were cleaned and shaped by using ProTaper rotary system (Dentsply Maillefer; Ballaigues, Switzerland) and the terminal 3mm of the roots were resected. Then, MTA and CEM cement were condensed in apical region with 3mm thickness. The samples were exposed to two environments with different pH values of 13 and 7.4. The leakage was assessed by using the fluid filtration technique at 1, 7, 14, 30 days intervals. Data were analyzed by the repeated measures MANOVA. RESULTS: There was no statistically significant difference in the rate of microleakage between neutral and alkaline pH of CEM cement and MTA (p> 0.05). The sealing ability of MTA in an alkaline pH of 13 was significantly less than CEM cement in this pH (p< 0.05). CONCLUSION: An environment with alkaline pH had no adverse effect on the sealing ability of MTA and CEM cement used as apical plugs. CEM cement had better sealing ability in alkaline pH.

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.