الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 120 |  |  |
| | | from | 120 | | |
Abstract
Accurate determination of working length is of paramount importance since it has a profound influence on ideal canal preparation, microbial disinfection and root canal system hermetic sealing. The estimation and preservation of the biological length of the root canal system has always been one of the major problems in endodontic treatments. Optimal healing condition is achieved with minimal contact between the obturation material and the apical tissue when the treatment of the root canal ends at the cement-dentinal junction.
Different methods were used to locate the canal terminus position and measure root canal working length. These include radiographic methods, electronic methods, tactile method and other adjunctive methods. But there’s no consensus in the literature on the best method of working length determination. Henceforth we designed the study to evaluate the validity of cone beam computed tomography, periapical radiography and apex locator in measuring endodontic working length in curved root canals of extracted human teeth.
This study was initiated with sample selection calculation; 15 freshly extracted human mandibular right first and second molars teeth were collected from the Department of Oral and Maxillofacial surgery, Faculty of Dentistry, Minia University, Egypt.
External root surfaces were cleaned from adherent tissues and hard deposits using ultrasonic scaling then disinfected by sodium hypochlorite for 30 minutes and stored in saline solution for use. Preoperative radiographs were taken in the mesiodistal and buccolingual directions to confirm the presence of a single canal and the absence of any exclusion criteria. Teeth were examined using 2.5X magnification Eye Mag Smart Loupes to exclude any teeth with pre-existing root fractures or cracks. All of the extracted teeth were numbered. Initial periapical radiograph was taken for each tooth to determine the angle of the root curvature according to Schneider’s method. Teeth with a degree of curvature ranging between 25° and 40° were included.
The selected teeth were washed in saline, and MB cusps were flattened to be used as a consistent and reproducible coronal reference for all the measurements. The root canal access cavities were prepared with high-speed diamond burs and an Endo Z drill following conventional guidelines. After completion of orifice opening and verification of canal patency, WL measurements were performed, as follows:
•CBCT Measurements.
•Radiographic Measurements.
•Actual Measurements.
•Electronic Measurements.
Results showed that there was a statistically significant difference between modalities (P-value <0.001). Pair-wise comparisons between modalities revealed that actual measurement showed the statistically significantly highest mean value and it was statistically significantly different from all other measurements. There was no statistically significant difference between CBCT (Sagittal view), CBCT (Coronal view) and radiographic tooth length; all showed statistically significantly lower mean value. There was no statistically significant difference between radiographic working length and electronic measurement; both showed the statistically significantly lowest mean values.
Under the condition of present study, it can be conclude that:
1.CBCT imaging has proven to be more accurate than periapical radiographs for preoperative working length estimation in curved root canals.
2.CBCT scans can be used as an alternative method for the WL determination. If a patient has a preexisting CBCT scan, the clinician should take advantage of this technique as an alternative, reliable method for determining the WL and offers the advantage of asses the anatomy of canal in 3 dimensions.
3.Modern electronic apex locator can determine this position with 95% accuracy with the actual working length, but still have some limitations.