The effects of various exposure times in the detectability on the tips of the endodontic files in Digora(R) / 대한구강악안면방사선학회지

ABSTRACT

Digora(R)-an intraoral digital radiography system utilizing image plate(IP) - has a dynamic range of expo sure time which allows it to decrease the patient's exposure time and to increase diagnostic ability through imge proces sing, transmission and storage. The purpose of this study was to evaluate the Digora(R) system by assessing the effects of various exposure times on the detectability on the tip of the endodontic file. Examining the root canals of 45 extracted sound premolars, K-files No. 10, 15, and 20 were placed at slightly varying distances from the apex. The teeth were glued onto resin-pla ster blocks. Five exposure times varying between 0.01 seconds and 0.25 seconds were used. Four observers were asked to m easure the distance between the tip of the file and a reduction of crown portion, and obtained mean errors (subtracting true file length from the measured file length), comparing Digora(R) monitors with E-plus films, which were bot h obtained under the same geometrical positions. The results were as follows 1. Comparing E-plus film with Digora(R) at 0.01 seconds, the mean errors in E-plus film showed -4.453mm, -4.49 7mm, and -3.857mm, while the mean errors in Digora(R) showed 0.065mm, 0.607mm, and 0.719mm according to the fil e groups. Therefore there was a significant difference between E-plus film and Digora(R)(P<0.05). 2. By comparison of mean errors according to the various exposure times in the Digora(R) system, the mean error at standard deviation was the highest at 0.01 seconds was significantly lower than that at 0.12 and 0.25 seconds in No . 10 and 20 file group(P<0.05). and the standard deviation was the highest at 0.01 seconds. 3. Comparing E-plus film at 0.25 seconds with the Digora(R) system, the mean errors showed a significant diffe rence between E-plus at 0.25 seconds and the Digora(R) system at 0.25 seconds in No. 10 and 20 file groups (P <0.05). 4. Comparing E-plus film at 0.25 seconds with other exposure times, the mean errors showed a significant difference between E-plus film at 0.25 seconds and E-plus film at 0.01 and 0.03 seconds in 10 file group(p<0.05). In the NO. 15 and 20 file groups, there was a significant difference between E-plus film at 0.25 seconds and E-plus film at 0.01 seconds(p<0.05). In conclusion, Digora(R) was better than E-plus film in detectability on the tip of the file at the exposure time of 0.01 seconds in all file groups. And we concluded that Digora(R) can shorten exposure times up to 4% of 0.25 seconds (0.01 sec), which is adequate exposure time for premolar in E-plus film using No. 15 and 20 files.