accuracy comparison of direct digital radiography [DDR] and conventional radiography in detecting chemically created lesions

Diagnosis of periapical pathology is of paramount importance in enabling the clinician to provide immediate and appropriate dental treatment. Both intraoral digital radiography and film radiography are used to detect periapical pathology. The purpose of this study was to compare the accuracy of digital radiographic imaging with conventional radiography in detecting chemically created lesions. For conducting this experimental study one cow cadaver mandibular Jaw was used. After building four 1x1cm[2] pools at first molar areas, 35% Hydrochloric acid solution used to create chemically lesions. The designed time for chemically lesions was 4, 12, 24 and 36 hrs following acid exposure. Then, 1 digital and 1 conventional image with E-Speed film was taken from each half-jaw and images evaluated by five examiners. Wilcoxon signed Ranks test used for statistical analysis. The results of this study showed that diagnosis were more precise in detecting lesions with RVG than conventional radiography. This difference was statistically significant [p<0.05]. Regarding the acceptable quality of digital radiographs comparing to conventional radiographs we suggest using this method for detecting bone lesions

[ effect of smear layer removal on permeability of dentinal tubules in human by dye penetration method]

The effect of smear layer on dentinal tubules is remarkable in endodontic treatments. The aim of this study was measuring the range of dye penetration in dentinal tubules with and without smear layer. Thirty extracted human teeth used in this study. At first, segments e prepared with 5 mm length from each tooth's root and then their canals widened by a 1/4 mm diameter bur, so that the smear layer appeared. The external, superior and inferior surfaces of the segments covered by 2 layers of nail varnish. The segments divided to 2 groups of 15 samples. The first group samples immersed in 17% EDTA for 2 minutes and then in 5.25% NaOCl for 20 minutes to remove the smear layer. After that the samples immersed in 2% basic fushin for 24 hours, the second group samples immersed in 2% basic fushin without removing the smear layer. After water rinse, all samples sectioned horizontally from middle of the root and photographs was taken of each samples surfaces. After transmitting the photographs to a computer, the percentage of the dye penetration into dentinal tubules of each sample calculated by Photoshop software. Due to results, the range of dye penetration in dentine tubules of the teeth with and without smear layer had no statistically significant difference [P-Value=0.120]. According to the result, smear layer removal have no effect on dentin permeability to dye penetration and dentin sclerosis is an important factor in this subject. Performing studies on the teeth with certain age and using other methods such as microbial permeability evaluation are needed

[Evaluation of antimicrobial effects of different calcium hydroxide preparation methods with direct exposure test]

Calcium hydroxide has a pronounced antimicrobial activity against most of the bacterial species found in the root canal and now is widely used as an intracanal medicament in endodontic therapy. The aim of this study was to evaluate the antimicrobial effect of different calcium hydroxide preparations with Normal saline, Lidocaine 2%, Chlorhexedin 2% and 0/2%, Iodine Potassium Iodide 2% and Glycerin on Entrococcus faeealis with direct exposure method. For conducting this experimental in-vitro study 375 sterile paper points were contaminated with the microbial suspension of Entrococcus faecalis. The samples were placed in sterile dishes and covered with creamy mixture of six different calcium hydroxide preparations. After 1.3, and 7 days tile paper points were immersed in test tubes containing BHI. Microbial growth was evaluated by turbidity in culture mediums. Data obtained showed that all of tested materials had perfect antimicrobial action but only in calcium hydroxide with Chlorhexidine 2% and 0.2% groups perfect antimicrobial action and no microbial growth was observed after 24 hours. Regarding the results of this study it is concluded that the vehicle of calcium hydroxide has not any significant effect on its antimicrobial activity, however, more studies on the effect of vehicles of chemical properties of calcium hydroxide such as its diffusion in similar conditions of root canal system, are needed

[Comparison of the apical leakage of root canals filled with MTA with those filled with gutta percha and lateral condensation technique]

Sealing the root canal system is of great importance in endodontic treatment especially in infected teeth. Several materials have been introduced for this purpose. The aim of the present study was to evaluate the sealing ability of MTA as an orthograde root filling material and compare it with laterally condensed gutta-percha with sealer. Thirty-six extracted human maxillary central and canine teeth were used in this experimental study. After preparation and surface disinfection with 1% NaOCI solution, the crowns of the teeth were cut at cement-enamel junction. Roots were randomly divided into four groups: two experimental groups of 15 roots each [gutta-percha with AH26 sealer and MTA] and two control groups of 3 roots each [positive and negative]. After root canal preparation and filling, the sealing ability of each technique was assessed by immersion in 1% methylene blue dye for 72 hours. Then the teeth were cleared and the extent of dye penetration was measured with a stereomicroscope. Data were analyzed by T-test with P<0.05 as the level of significance. The results showed that the mean microleakage was 1.1 mm [SD=2.1] in the gutta percha group and 3.4 mm [SD=2.1]in the MTA group. This difference was statistically significant [P=0.013]. Based on the results of this study, canal obturation with gutta-percha and AH26 sealer may provide a better apical seal compared with MTA. However, further studies on microbial leakage are needed for more precise evaluation of the sealing ability of MTA

Root canal morphology of human mandibular incisors in Yazd province

An in vitro study was performed to determine the number and the type of root canals of mandibular incisor teeth in an Iranian population. Sixty eight mandibular incisor teeth were immersed in India ink decalcified and cleared. It was found that 55.9% of the teeth had two canals that in 51.5% of them the canals merged into one canal before exiting the tooth through one apical foramen. Because of high percentage of two canals in lower mandibular incisors, there should be more attempt to detect the second canal during access preparation

comparative study of root canal preparation using flexmaster rotary and NiTi hand files

Maintaining the original canal path and safety of canal preparation during instrumentation in curved canals have been subjected to many challenges. The aim of this study was to compare several parameters of root canal preparation using flexmaster rotary and hand used Nickel-Titanium instruments. In this experimental study, sixty extracted human teeth with root canal curvatures between 10 and 42 degress were devided into two similar groups with equal mean curvatures. Root canals in one group were prepared using flexmaster rotary instruments and the other with NiTi hand files.After canal preparation, different parameters such as straightening of curved root canal, loss of working length, fracture rate, perforation and working time, were evaluated and compared between the two groups. Data were analyzed by t student test with p<0.05 as the limit of significance. Results showed that both instruments maintained the original canals' curvature. No loss of working length, instruments fracture or perforation was recorded. Working time was significantly shorter for flexmaster than hand files. Both systems under investigation respected original root canal curvature and were safe to use. Therefore the rotary techniques could be successfully introduced to undergraduate endodontic programmes