Removal of smear layer by two endodontic irrigation solutions and erbium: yttrium, aluminum, garnet [Er:YAG] laser: a scanning electron microscope [SEM] study

The purpose of the present study was to determine the effect of 17% Ethylene, di-amine, tetra-acetic acid [EDTA], 6% phosphoric acid and Erbium: Yttrium, Aluminum, Garnet [Er:YAG] Laser in removing the smear layer by scanning electron microscopy. In this study, 80 single-rooted human teeth were selected. Instrumentation was done by use of hand files and step-back technique up to file #40 at apical and file #80 at coronal area. During instrumentation, 1ml of 5.25% sodium hypochlorite [NaOCl] was used as irrigation between each file. The teeth were randomly divided into four groups with different methods of smear removal.17% Ethylene, di-amine, tetra-acetic acid was used in group 1, 6% Phosphoric acid in group 2, Erbium: Yttrium, Aluminum, Garnet laser in group 3, and no intervention in group 4 [as control]. Roots were then longitudinally sectioned and prepared for scanning electron micrograph in cervical, middle and apical areas. Data were analyzed by Kruskal-Walis, Mann-Whitney, Friedman and Wilcoxson tests [P<0.05]. The results showed a significant difference in smear layer removal between three methods in favor of the EDTA [P<0.001] and Phosphoric groups [P<0.001] with no significant difference between them [P=0.49]. Although Er:YAG laser showed some limited ability to remove the smear layer, the effectiveness was not significantly different from the control group [P=0.157]. Based on the findings of this study, EDTA and Phosphoric acid were effective methods to remove smear layer from the root canal walls but Er:YAG laser showed less efficacy compared to the other experimental groups

Graphite application and different powers of neodymium-doped yttrium aluminium garnet [Nd:YAG] laser on dentin surface changes: a scanning electron microscopy study

Various methods have been used for the treatment of dentine hypersensitivity such as dentifrices, sealants and different types of lasers. The aim of this study was to evaluate the effect of Neodimium:Yttrium-Aluminium-Garnet [Nd:YAG] laser in association with graphite on the dentin morphologic changes. In this experimental in vitro study, 16 freshly extracted third molars were selected. 5 specimens with the dimensions of 2×2×1 mm from root trunk were prepared. Specimens were randomly divided into five groups: group 1 [control, no laser irradiation]. Group 2, 3 irradiated by Nd:YAG laser 0.5 and 1W, output power respectively. Group 4, 5 smeared with graphite and then irradiated by Nd: YAG laser 0.5 and 1W output power. Samples were prepared for scanning electron microscopy. Number and diameter of dentinal tubules were determined in different groups and analyzed with the Kruskal-wallis and Mann-Whitney tests [SPSS 16]. The number of tubules had significant difference between all groups [P<0.001], except group 1 in comparison with group 2 [P> 0.05], and group 3 in comparison with group 4 [P> 0.05]. Micro-cracks and rupture of melted dentin materials were seen in group 4 and 5. According to the findings of this study, smearing with graphite on dentin surface increase the absorption of Nd:YAG laser energy and reduced the diameter and number of open dentinal tubules

Assessment of canal configuration in maxillary first and second molars in the city of Isfahan

The human teeth have different anatomical variations and treatment of each tooth is under the influence of its configuration. The root canal anatomy, not only in various teeth, but also in one tooth might be different. The important point is to understand the canal anatomy that is essential for root canal therapy. In various studies, different results have been reported from different regions of the world, additionally a number of studies have shown different trends in shape and number of roots and canals among different races. Since there is a lack of information about canal configuration in the city of Isfahan, therefore this study was done to determine the frequency of canal configuration in maxillary first and second molars This study was descriptive, that was done on 160 extracted maxillary first and second molars, which were collected from clinics and private offices in the city of Isfahan. Pulp tissue was removed and canal system was stained with Indian ink, the teeth were decalcified with 10% nitric acid, dehydrated and cleared with methyl salicylate. Maxillary first molars were additionally cut in cross sections in three points of the root and canal configuration of teeth were evaluated. The examination of root canal systems of teeth was based on Weine classification. The majority of maxillary first and second molars had three separate roots. A variety of canal types were found in mesiobuccal [MB] roots of first and second molars. More than half of the MB roots of first molars [61%] had two canals, whereas MB roots of second molars mostly had type I canals [76.38%] in the clearing method. The palatal and distobuccal canals mainly had type I canal configuration. In the sectional method more than half the MB roots of first molars had two canals [78.47%]. In other countries many researches have been done using different methods about internal anatomy of teeth and the results are different from this study. It appears that the differences are caused by genetic factors and methods used. Also results of this study were different in types I and IV in MB roots in the two methods, this difference is probably due to better access and visibility to canal in the sectional method