[ comparison of accuracy of determining the root canal working length by different magnifications of digital radiography]

Successful root canal therapy is related to cleaning, shaping and obturation of the root canal system with a proper limited working length. Therefore, these are achieved by knowledge of root canal anatomy and radiograph images. Current radiographic techniques are elementory methods. With the advancement of computer technology, and due to limitations that exist, in this recent decade significant attention has been given to digital radiography. Software programs for digital radiographic systems, such as magnification of different images is a tool assistant for digital systems in increasing precision. The purpose of this study was to compare different magnifications of digital radiography to determining canal length. In this experimental in vitro study, 30 human anterior teeth were selected and cleaned in detergent. The actual working length was measured with a N.15 file. Then the teeth were casted and the files were inserted in canals in 3 different positions, proper, under and over. Ninety images of the teeth in three magnifications were made and working length was evaluated by three endodontists randomly. Then the Friedman test was used for statistical analysis. After statistical analysis, the results showed that there was no significant differences between the groups. But there is significant difference in 2X magnificantion of under working length to real working length. In conclusion, it can be stated that magnification of digital radiography can not be helpful in determination of working length especially in under position

[Laboratory comparison of microleakage of Ideal Makoo and tetric flow composites using two dentin adhesives]

Introduction: this study evaluated the degree of microleakage of Ideal Makoo and Tetric Flow composites using two dentin adhesives of Scotch Bond Multipurpose [SBMP] and Excite

Materials and Methods: sixty premolar teeth were divided into four groups of 15 and class V cavity preparations were done in CEJ. Group 1 was restorated with SBMP and Ideal Makoo, Group I1 with SBMP and Tetric Flow, Group I11 with Excite and Ideal Makoo, and Group IV with Excite and Tetric Flow. Stereomicroscope [X40] was used to evaluate and dye penetration in occlusal and gingival margins. Chi Square test, Pearson's correlation test and Fisher's exact test were used for data analysis [a= 0.05]

Results: the degree of leakage was not in correspondence to the type of composite. 1- The degree of leakage was not in correspondence to the type of dentin adhesive. 2- In four groups, the degree of leakage in gingival wall was significantly more than occlusal wall

Conclusion: the type of composite and dentin adhesive have no effect on degree of leakage. The important factor was the type of wall. It means that in class V restorations, gingival wall is always observed to have more microleakage than occlusal wall

[ effect of flowable composite as a liner under amalgam in fracture strength of endodontieally treated posterior teeth]

Introduction: adhesive restorations in endodontieally treated posterior teeth could increase the strength of teeth and decrease the microleakage. The aim of this study was to evaluate the effect of flowable composite as a liner as well as an internal splint. Agent on bond strength of endodontieally treated molars restored with amalgam

Materials and Methods: this study was an interventional study which evaluated the fracture resistance of endodontieally treated molars in two groups based on cavity preparation of class II MOD or MOD in combination with lingual cusp reduction. Each group was divided into four subgroups and restored with 1 and 2] Tetric Flow and amalgam with and without prefabricated post, 3 and 4] Copalite and amalgam with and without prefabricated post. The control group consisted of intact molar teeth. After the restorations were made, the specimens were stored at 37oc with 100% humidity for 24 hours and then submitted to the load cycling [500,000 cycles] simultaneously with thermal cycling [5oc and 55oc]. Analysis of data was done by ANOVA and Duncan test with 95% significance level

Results: two factors [Post and cavity preparation] had a statistical interaction wit11 each other [P<0.05]. This means that without post, amalgam cuspal coverage restorations were able to increase the fracture resistance of teeth significantly but with post, they were not able to do so. Post and Tetric Flow had no effect on fracture resistance individually [P>0.05], and control group showed the most fracture resistance [p<0.05]

Conclusion: in patients with suitable occlusion, lingual cusp reduction and restoration with amalgam without intracanal pin could be an acceptable treatment