Hydroxyl ion diffusion through intact and resorbed roots at various time intervals

INTRODUCTION: The purpose of this study was to investigate root surface pH changes over a period of 4 weeks following treatment with calcium-hydroxide dressing of intact and resorbed roots. MATERIALS & METHODS: The canals of 30 single-rooted teeth were instrumented with ProTaper rotary files and randomly divided into 2 experimental groups of 14 each, and one control group with two samples. To simulate external resorption in group 2 and control, two defects were made on the buccal and lingual mid-root surfaces of each tooth with a diamond bur (1×1mm). Teeth were then submerged in 20% sulfuric acid for 4 days. Canals of 14 intact teeth in group 1, and 14 resorbed teeth in group 2 were filled with calcium hydroxide Ca(OH)2 while canals of resorbed teeth in control group were filled with saline. All teeth were then placed in a glass vial containing 15mL of deionized water (pH≈7). The pH of water was measured at 0 and 1, 4, 7, 10, 14, 21 and 28 days using pH microelectrode. Independent t-test and repeated measured ANOVA analyzed the data. RESULTS: Except a mild decline at 7days and 14days, the average pH values showed increased during the time periods of this study. Day 28 showed the maximum pH average value in both groups (7.67-7.72) (P<0.05). Significant increase of pH values were detected at different time intervals compared with the baseline time (P<0.05). CONCLUSION: Diffusion of hydroxyl ions was similar in both resorbed and intact roots. In both groups pH values were significantly higher than the baseline pH at the various times

A New Approach to Root Formation

In endodontics, treatment of an open apex tooth with necrotic pulp is a problem. It seems that with promotion of remnants of Hertwig’s epithelial sheath or rest of malassez accompany with a good irrigation of root canal we can expect root formation

The effect of one-step or two-step MTA plug and tooth apical width on coronal leakage in open apex teeth

Introduction: Mineral trioxide aggregate (MTA) has been suggested as an effective material for apical barrier, forming an effective seal against bacterial leakage in teeth with open apices. MTA needs moisture for setting; which can come from the apical region or a moist cotton pellet. This study was intended to compare bacterial leakage in one- and two-step MTA apical barrier technique in open apices with different diameters.Materials and Methods: The root canals of 52 extracted human maxillary incisors were prepared and open apices in two different diameters of 1 and 1.4 mm were created. The samples put in experimental groups randomly. A 4-mm thickness of MTA was placed as apical barrier for both one- and two-step methods. In one-step groups (1.4 mm diameter; n=12 and 1 mm diameter; n=12), the samples were obturated immediately after placing MTA plug. For two-step groups (1.4 mm diameter; n=12 and 1 mm diameter; n=12), a moist cotton pellet was placed over the MTA plug for 3 days before root canal obturation. Four samples served as positive/negative control groups. After one week, microleakage was evaluated using bacterial penetration technique and results were statistically analyzed utilizing SPSS software and Chi-square test.Results: In one-step technique 13 and in two-step technique 12 samples showed bacterial leakage. There was no statistically significant differences between two techniques (Chi square, P=1). The difference between the results related to 1 and 1.4 mm apical foramens was also not significant (P=1). Also 12 and 13 samples showed bacterial contamination in teeth with 1 mm and 1.4 mm apical foramens, respectively (P=1).Conclusion: It seems that leakage of MTA apical plug using one- and two-step technique is comparable; however, in vivo investigations are highly recommended for more accurate results

External root resorption: Arrested or progressing?

External root resorption may be an uncontrolled phenomenon, and the most known interventions have no effect. Even progressive external root resorption may not be controlled by long term Ca(OH)2 therapy. Currently, there are no treatment options for vital tooth that suffer from root resorption. This invasive resorption can lead to extraction of the tooth. The use of new technologies such as low power laser may control this type of resorption

Recent advancements in the application of new monomers and membrane modification techniques for the fabrication of thin film composite membranes: A review

Thin film composite (TFC) membranes have been experiencing significant modifications recently aiming to improve their structure, properties and separation efficiency. One of the promising modifications to tailor the membranes more efficient is changing the materials used. m-phenylene diamine (MPD), piperazine (PIP), and trimesoyl chloride (TMC) are the most common monomers used to fabricate TFC membranes. Recent studies have introduced several alternatives to these traditional monomers showing significant contribution of these monomers to the physicochemical properties of the membranes (e.g., surface roughness, hydrophilicity, cross-linking density, chemical structure) as well as membranes\u27 separation efficiency. Emergence of more favorable functional groups such as carboxylic and amine groups due to the new materials integration facilitates the polymerization process and is beneficial to the membrane properties. Here, a critical review on the new interfacial polymerization monomers applied for reverse osmosis (RO) and nanofiltration (NF) membranes fabrication is presented. The membrane molecular structure and fabrication mechanism are investigated in details. This is followed by a review of the recent surface modification methods including grafting, coating and additive incorporating into the thin layer of membranes. The application of alternative monomers to MPD, PIP and TMC are investigated and the benefits of using these monomers or co-monomers are discussed

FTIR microspectroscopy reveals chemical changes in mice fetus following Phenobarbital administration

Phenobarbital is a phenobarbiturate used as a sedative, anticonvulsant or hypnotic with the doses prescribed and can cause teratogenic effects. The goal of this study was to examine an alternative method for the recognition of the mechanism or the bimolecular potential changes in mice fetus caused by Phenobarbital using FTIR micro spectroscopy. The mice were injected with Phenobarbital (120 mg/Kg) on gestation day 9. Fetuses were dissected on day 15 of gestation and morphological and histological studies on the fetus were carried out. Sections (10 μm) of normal and Phenobarbital treated fetus brains and livers were used for FTIR measurement in the wave number region of 400- 4000 cm. The results were shown by 2 derivatization of spectra and also subtracting from control spectra. In liver, the intensity at 1054 cm, 1155 cm, 1353 cm, 1453cm,1645 cm, 1622 cm, 2944 cm, 2913 cm and 2845 cm were shifted and increased. In the brain, the intensity at 879 cm, 911 cm, 955 cm, 1223 cm, 1256 cm, 1304 cm, 1360 cm, 1453 cm, 1529 cm, 1636 cm, 2845 cm, 2915 cm and 2950 cm were increased and shifted. The most important changes of the fetus brain tissue are on the β structure of proteins due to the amide I bands at 1636 cm, while extensive effects on the DNA structure were obvious for the Phenobarbital treated liver tissues. As a conclusion, FTIR spectroscopy might well be assumed as a potentially powerful teratogenic measurement instrument with a unique ability to identify the modified bimolecular structures. © 2015 by School of Pharmacy Shaheed Beheshti University of Medical Sciences and Health Services

In Vitro Comparison of Gutta-Percha Removal with H-File and ProTaper with or without Chloroform

Introduction: Removal of root filling materials is one of the key steps in success of root canal retreatment. The purpose of this study was to evaluate the efficacy of H-File and ProTaper with or without chloroform in the removal of gutta-percha during retreatment of mandibular premolars. Materials and Methods: Sixty mandibular premolars with one canal, and curvatures less than 30 degrees were used in this experimental study. They were instrumented with K-files and laterally obturated with condensed gutta-percha using AH26 as the sealer and were stored in 100% humidity at 37°C for 2 weeks. The teeth were randomly divided into four groups of 15 teeth each. Removal of gutta-percha was performed with H-File and ProTaper. All techniques were used with or without chloroform. The teeth were split longitudinally and the area of remaining gutta-percha/sealer on the root canal wall was explored under stereomicroscope. Retreatment time duration was also recorded for each sample. Data were analyzed statistically by Two-way ANOVA, t-test and Tukey’s. Results: In all groups, no significant difference was found in remaining gutta-percha and sealer with or without using chloroform, but chloroform shortened the time of retreatment. ProTaper left significantly less remaining filling materials than H-File (P<0.05). Retreatment time was significantly different between the studied groups (P<0.001). Conclusion: ProTaper Ni-Ti instruments proved to be more efficient and time-saving devices for removal of gutta-percha compared to H-File in canals with no or slight curvature

Comparison of Pulpotomy with for Mocresol and MTA in Primary Molars: a Systematic Review and Meta - Analysis

Introduction: There are various studies looking at the effects of formocresol (FC) and mineral trioxide aggregate (MTA) on pulpotomy of primary molars. This is a systematic review of literature comparing the success rates of MTA and FC in pulpotomy of primary molars. Materials and Methods: The study list was obtained using PubMed, EMBASE, Scopus, Science Citation Index, Iran Medex, Google Scholar, the Cochrane Library, and also some hand searches contains through dental journals approved by the Iranian Ministry of Health. Papers which met the inclusion were accepted. The quality of studies for the meta-analysis was assessed by a series of validity criteria according to Jadad's scale. Eight qualified studies met the criteria. Terms of clinical outcomes and radiographic findings were evaluated in all studies to assess clinical success and root resorption. Fixed model was applied to aggregate the data of homogenous studies. A random effect model was carried out for measuring the effect size of heterogeneous studies. Results: The overall clinical and radiographic success rates based on the data suggested that MTA was superior to FC (P=0.004) with the Odds Ratio=3.535 and 95% confidence interval (1.494-8.369). Conclusion: Primary molars pulpotomy with MTA have better clinical and radiographic success rates than FC

Autogenous Transplantation for Replacing a Hopeless Tooth

Autogenous tooth transplantation (ATT) is a simple and reasonable choice for replacing the missing teeth when a proper donor tooth is available. This report presents a case of successful ATT of a maxillary right third molar for replacement of mandibular right second molar with a concomitant endodontic-periodontal disease. The mandibular second molar was believed to be hopeless due to a severe damage to coronal tooth structure, inappropriate root canal treatment and apical radiolucency. After extraction of mandibular second molar and maxillary third molar (the donor), the tooth was re-implanted into the extracted socket of second molar site. Root canal therapy was then performed. After 3 years, clinical and radiographic examinations revealed satisfying results, with no signs and symptoms. The patient is asymptomatic and the transplanted tooth is still functional with no signs of marginal periodontal pathosis. Radiographies showed bone regeneration in the site of previous extensive periapical lesion, normal periodontal ligament with no signs of root resorption.Keywords: Autogenous; Auto-Transplantation; Endodontic; Surgical Procedure; Third Mola

The effect of blood on apical microleakage of Epiphany and AH26: An in vitro study

INTRODUCTION: Blood contamination of the canal during preparation can be a major problem in endodontics; this may result in apical microleakage. The aim of this in vitro study was to evaluate the effect of blood on apical microleakage of a resin-based root canal sealer (AH26) and a polymer-based root canal sealer (Epiphany).MATERIALS & METHODS: In this experimental study, 50 decoronated central incisors and canine teeth were prepared by RaCe rotary system and randomly divided into 4 groups (n=10). Groups A1 and A2 were obturated by Epiphany/Resilon and AH26/Gutta-percha, respectively. The obturations were performed with a single cone technique after drying root canals. In B1 and B2 groups, the test groups, 0.02cc citrated human blood was injected into dried root canals and they were obturated in the same manner. Ten specimens were served as positive and negative controls (n=5).The apical leakage was measured by means of a computerized fluid filtration method after 1 day and 3 weeks. The data was analyzed by One-Sample Kolmogorov-Smirnov, Independent Sample t-test and univariate analysis. Statistical significances were preset at α=0.05. RESULTS: There was no significant difference in apical microleakage of the two sealers after 1 day and 3 weeks in dry and blood environment (P>0.05). Sealer and environment had no interaction (P>0.05).CONCLUSION: Blood contamination has no significant effect on the apical microleakage of Epiphny and AH26