[Comparison of obturation density using nickel titanium and stainless steel spreaders by lateral compaction technique]

The density of Gutta-percha is an important factor in canal seal and root canal treatment success. So, the present study intended to compare the effect of Ni-Ti and S-S spreaders on the intracanal Gutta-percha weight. In this experimental study, 40 simulated canals with 40 degree curvature [group 1 and 2] and 40 simulated canals with 10 degree curves [group 3 and 4] were used. Each block was weighted after cleaning and shaping using Flexmaster rotary instruments. Group 1 and 3 blocks were obturated using Ni-Ti spreaders, while group 2 and 4 blocks were obturated using stainless steel spreaders with Gutta-percha. The simulated canals were again weighted and the difference of the two measurements was calculated as the Gutta-percha weight. The results were analyzed using SPSS software and 2-way ANOVA tests. The analysis showed that there was no significant difference between the four experimental groups. In addition, the effect of the canal curvature, spreader type and the interaction of the variables was not statistically significant. The current study showed that different spreader types [Ni-Ti or S-S] do not affect the Gutta-percha weight of the root canal obturation

[In vitro evaluation of the accuracy of two new electronic apex locators in root canal length determination]

Radiography is still the common method of measuring working length in root canal therapy. While, gag reflex, pregnancy or superimposition of anatomical structures on root canal may be considered as some of the limitations to this procedure. Therefore, application of any accessory measurement device may be useful. The aim of this investigation was to assess the ability of two apex locator systems [Ipex and Raypex5] in measuring root canal length accurately. A total of 160 extracted human teeth were used in this laboratory investigation. The teeth were divided into 3 groups of single-canal, two-canal and three-canal teeth. The access cavities were then prepared and the actual length of each canal was measured by inserting an appropriate file into the canal until the tip of the file was seen at the apical foramen. The Donnelly test medium was prepared and each tooth was placed in the medium up to the CEJ. The length of each tooth was measured again and recorded using Ipex and Raypex5 systems. The data were statistically analyzed using Liner-Regression, McNemar and t-tests. The accuracy of Raypex5 showed to be 83.1% [95% CI: 77.3-89]. Likewise the accuracy of Ipex was 78.8% [95% CI: 72.3-85.2]. Both measurements were with in the limits of +/- 0.5mm from apical foramen. Mc Nemar test showed no significant difference between the two groups [P=0.337]. Based on the results of this study, it can be concluded that manufacturers' data are not always reliable. However, these systems can be used as accessories in addition to radiography for accurate working length measurements

[Assessment of canal configuration of maxillary second premolars and comparison of laboratory and clinical methods of assessment in patents treaded at the endodontics department of lsfahan School of dentistry]

Recognizing canal configuration is necessary for correct endodontic therapy; and having no information about canal configuration results in failure of therapy. Since one of the most effective factors in canal configuration is race, we decided to conduct a laboratory and clinical research in Isfahan. The aim was to recognize canal configuration of the maxillary second premolars and compare the clinical and laboratory results.1- Laboratory study [In vitro]:At first we selected 105 maxillary second premolars and then disinfected them in CLONA 5.25%. We made a correct access cavity on the teeth. In order to vacate pulp tissue in chamber and canals, we placed them in H2O2 35% for 15 days. Then, we placed them in HNO3 [5%] for 3 days in order to be decalcified. 70%,90%,100% isopropyl alcohol was used to dehydrate the teeth. After the above processes, we injected India ink in -1.8 P in the canals and sealed access cavity by zonaline cement. Methyl Salicylate was used to clear the teeth and the configuration of the canals were observed directly. 2- Clinical study [In vivo]: In this study, we selected 132 maxillary second premolars of patiuents treated at the graduate and under graduate departments of Isfahan University School of Dentistry. Then we studied every radiograph using a negatoscope and the results of both methods were analyzed and compared. 1-Laboratory [In vitro] Out of 105 maxillary second Premolars[researchable], 30 type I [28.6%], 13 type II [%12.4], 48 type III [45.7%], 12 type IV [11.4%] and 2 with three canal [1.9%] were observed according to the Weine classification.2-Clinical [In vivo] Results: Out of 132 maxillary second premolars, 82 were type I [62.13%], 21 type II [15.91%], 25 type III [18.92%], and 4 were type IV [3.04%] . In this study, three canals were not observed. The results of this study are different from other researches. Perhaps, race and method of study were influential. Also, the clinical results were different from laboratory results as the laboratory study method is more exact