بررسي دقت راديوگرافي در اندازه گيري طول ريشه و مقايسه آن با موقعيت هيستولوژيك تنگه اپيكان

Evaluation of the Radiographic Accuracy in Root Length Determinant its comparison with histological status of the apical constriction

Working length determination is one or the most important parts of every root canal treatment procedure. It is of wide spread acceptance that the most common method to determine the working length for endodontic treatment is through the use of radiographs. The aim of this study was to evaluate the accuracy of the radiographs in showing the distance between the files tips and microscopic CDJs and apices under clinical circumstances. Hence a cadaver containing 27 maxillary and mandibular teeth was used. At the beginning the Jaws were separated from the skull and mounted on a hinge articulator. After taking primary parallel radiographs, access cavities were prepared and No. 15 K-files were placed within each canal. The radiographic soft tissue was simulated by the means of medium- boiled chickens and water- filled examination gloves. Another array of parallel X-rays were taken and the lengths of the files were corrected at 0.5 mm to the radiographic apices the final Radiographs were taken by the means of planmeca Prostyle Intra and EndoRay and with specified KVP, current and exposure time for each tooth. Each radiograph was developed and fixed by Velopex and digitized by 6-megapixelled FujiFilm FinePix cameras. The distance between each file tip and radiographic apex was measured by the software, Veewbox 3 and by three observers. On the other hand, the teeth were extracted and sectioned mesiodistally. The distance between each file tip and CDJ was viewed under the stereomicroscope by the same observers. (With 2x magnification) The results were evaluated in three parts: 1-Comparison of the disrance between the file tips to radiographic vs. microscopic apices. 2- Comparison of the distance between the file tips to radiographic VS. Microscopic CDJs. And 3-Evaluation of the difference between the values measured by the three observers. Statistical analysis did not indicate any significant difference in distance between the radiographic and microscopic apices to the file tips measured by the first observer (p>0.05). In measurements taken by the second and third observers however, there was a significant difference. In addition, there existed no significant difference among the three observers in the distance between the microscopic and radiographic CDJs and file tips. Eventually, there was not any significant difference among the three observers in the recorded values. According to the previous studies and the current investigation, it can generally be said that parallel radiographic technique can reliably be used to locate the apex at the confidence revel of 95%. According to this study CDJ is located 0.5mm cervical to the radiographic apex.