in vitro study of mesiobuccal root thickness of maxillary first molars

Understanding the internal anatomy of root canal system can significantly influence outcomes of root canal treatment. The aim of this in vitro study was to measure the thickness of mesiobuccal root at different levels in maxillary first molars. In this cross-sectional study, forty extracted human maxillary first molars were radiographed; accordingly, the mesial and distal root thicknesses of mesiobuccal [MB] roots were measured at four parallel horizontal levels. The samples were sectioned at the measured levels and then sections were scanned and saved in the computer. Buccal [B], Palatal [P], Mesial [M] and Distal [D] aspects of root thicknesses in single-canalled roots were measured. In two-canalled mesiobuccal roots, Distobuccal [DB] and Distopalatal [DP] aspects were evaluated alongside other measurements. Average radicular thickness in each aspect and each level was compared using ANOVA and t-test. A total of 25 had two canals and 15 had one canal in MB root. In single-canalled roots M and D aspects were the thinnest whereas in two-canalled samples, the thicknesses of DP and DB aspects were significantly less than others [P<0.001]. The B and P had the greatest thicknesses in all the samples. The results showed that special attention should be paid to "danger zone" areas of mesiobuccal maxillary first molar roots in order to avoid technical mishaps

[Accuracy of reverse contrast option of digital radiography in detection of horizontal root fracture.[in vitro]]

Background and Aim: Detection of Horizontal root fracture is completely related to radiography and application of new methods is indispensable .The aim of this study was to compare the diagnostic accuracy of reverse contrast option of digital radiography with original images for detection of horizontal root fracture

Materials and methods: In this diagnostic study, digital radiographs were taken from 40 maxillary anterior teeth mounted in a dry alveolar socket with vertical angles of 0[degree sign]and 15 [degree sign] .Root fractures were created in the horizontal plane on each root and after relocating root fragments radiographs were repeated in a same position. Images were processed with reverse contrast option and assessed by observers. Data were analyzed with proportion test and Cochran's Q test

Results: There was no significant difference in sensitivity, specificity, PPV[Positive Predictive value] and NPV [Negative Predictive Value] between 0[degree sign]and 15[degree sign]radiographs in original and reverse contrast images. In either image groups, when fractures were certainly diagnosed by observers, 0[degree sign]radiographs obtained higher sensitivities [P=0.014] Also when fractures were likely diagnosed , sensitivity and NPV were significantly higher for 0[degree sign]radiographs [P=0.035] ,[P=0.023]respectively

Conclusion: The diagnostic accuracy of reverse contrast option of digital images are equal to original images, although 0[degree sign]radiographs are more appropriate

Efficacy of two rotary systems in removing gutta-percha and sealer from the root canal walls

The aim of this in vitro study was to compare the efficacy of two retreatment rotary systems in removal of gutta-percha [GP] and sealer from the root canal walls with and without use of solvent. Sixty single-canalled distal roots of mandibular molars were prepared and root filled with gutta-percha and AH26. Each canal was randomly allocated to receive one of the retreatment techniques, Mtwo R or ProTaper. The groups were further divided into two subgroups: with or without the use of solvent. The cleanliness of canal walls was determined by stereomicroscope and scanning electron microscopy. The results showed that Mtwo R without the use of solvent was more efficient in material removal compared to ProTaper D [P<0.05]. Most remnants were found in the apical third of the canals [P<0.05]. Mtwo R seems to be an efficient rotary system for endodontic retreatment of root canal with GP

Endodontic treatment of a maxillary first premolar with type IV buccal root canal: a case report

The maxillary first premolar may present large number of anatomic variations. The clinician should be aware of the configuration of the pulp system. Maxillary first premolars usually have two canals. The incidence of three canals in these teeth is quite rare. This case report presents the diagnosis and clinical management of a maxillary first premolar with two distinct canals in the apical third of buccal root [type IV], drawing particular attention to tactile examination of all the canal walls

Technical quality of root canal treatment performed by undergraduate dental students

This study was carried out to evaluate the technical quality of root canal treatment [RCT] performed by undergraduate dental students at the Islamic Azad University in Tehran, Iran. Four-hundred records of patients who had received RCT at faculty of dentistry, between the years 2004-2006 were evaluated. For each treated tooth at least three periapical x-rays were assessed: preoperative, working length measurement, and postoperative. Evaluation of root canal filling was based on two variables: length and density. The filling length was recorded as adequate, under- or overfilled. Density of filling was recorded as poor or adequate. Fillings with adequate length and density were recorded as acceptable. Detected iatrogenic errors were: ledge formations, root perforations, furcation perforations, strip perforations and presence of fractured instruments. Results were evaluated statistically using one-way ANOVA and Chi-square analysis. Out of the 400 teeth, 50.5% had at least one of the mentioned errors. Acceptable filling was observed in 32.5% of all studied teeth. Ledge was found in 17.5% of the teeth. Canal curvature was the most important factor associated with ledge formation [P<0.05]. The technical quality of RCT performed by undergraduate dental students using step-back preparation and cold lateral condensation was classified as acceptable in 32.5% of the cases

Comparison of extracted teeth and simulated resin blocks on apical canal transportation

We aimed to compare apical canal transportation of extracted teeth and two types of simulated resin blocks. Mesiobuccal root of extracted maxillary molars, high hardness simulated resin blocks [Knoop hardness=40] and low hardness simulated resin blocks [Knoop hardness=22] were prepared with K-files using step-back technique [n=15 canals in each group]. Double exposure radiographic technique was used for extracted teeth. Simulated resin blocks were stabilized and scanned before and after preparation. Pre and post-preparation pictures were superimposed and apical transportation was measured. The data were analyzed statistically using ANOVA and Tukey HSD tests. There was no significant difference in apical canal transportation between extracted teeth and high hardness resin blocks [P>0.05]. Low hardness resin blocks showed more apical transportation than the other groups [P<0.05]. Under the conditions of this study, apical canal transportation for extracted teeth and high hardness simulated resin blocks were similar