• The Journal of the Korean dental association
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• v.50 no.7
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• pp.420-430
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• 2012

Purpose: The purpose of this study was to measure the absorbed dose and to calculate the effective dose for full-mouth periapical radiography using the portable dental x-ray machine and panoramic radiography Material and Method: Thermoluminescent chips were placed at 25sites throughout the layers of the head and neck of a tissue-equivalent human skull phantom. The man phantom was exposed with the portable dental x-ray machine and panoramic unit. During full-mouth periapical radiography the exposure setting was 60 kVp, 2 mA and 0.15 ~ 0.25 seconds, while during panoramic radiography the selected exposure setting was 72 kVp, 8 mA and 18 seconds. Absorbed dose measurements were obtained and equivalent doses to individual organs were summed using ICRP 103 to calculate of effective dose. Result: In the full-mouth periapical radiography, the highest absorbed dose was recorded at the mandible body follow with submandibular glands and cheek. Using panoramic unit, the highest absorbed dose was parotid glands and the following was back of neck and submandibular glands. The effective dose in full-mouth periapical radiography using portable dental x-ray machine was 46 ${\mu}Sv$. In panoramic radiography, the effective dose was 38 ${\mu}pSv$. Conclusion: It was recommended to panoramic radiography for general check in the head and neck area because that the effect dose in the panoramic radiography was lower than the dose in the full-mouth periapical radiography using portable dental x-ray machine.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.3
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• pp.184-190
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• 2012

Purpose: The purpose of this study was to measure the absorbed dose and to calculate the effective dose for one periapical radiography using the portable and wall type dental X-ray machines. Materials and methods: Thermoluminescent chips were placed at 25 sites throughout the layers of the head and neck of a tissue-equivalent human skull phantom. The man phantom was exposed with the portable and wall type dental X-ray machines. For one periapical radiography taken by portable dental X-ray machine, the exposure setting was 60 kVp, 2 mA and 0.2 seconds, while for one periapical radiography taken by wall type dental X-ray machine, exposure setting was 70 kVp, 8 mA and 0.074 seconds. Absorbed dose measurements were performed and equivalent doses to individual organs were summed using ICRP 103 to calculate effective dose. Results: In the upper anterior periapical radiography using portable dental X-ray machine and in the lower posterior periapical radiography using both machines, the highest absorbed dose was recorded at the mandible body. The effective dose in upper anterior periapical radiography using portable and wall type dental X-ray machines was $4{\mu}Sv$, $2{\mu}Sv$, respectively. In the lower posterior periapical radiography, the effective dose for each portable and wall type dental X-ray machines was $6{\mu}Sv$, $2{\mu}Sv$. Conclusion: It was recommended that the operator use prudently potable dental X-ray machine because that the effective dose in the periapical radiography using wall type dental X-ray machine was lower than that in the periapical radiography using portable dental X-ray machine.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.29 no.1
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• pp.255-260
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• 1999

Purpose: The objective of this study was to evaluate the possibility of substitution of the zonography for the full-mouth periapical radiography in aspect of radiation protection. Materials and Methods: Rando phantom and LiF TLD chips were used for dosimetry. The absorbed doses at brain, skin above the TMJ. parotid gland. bone marrow in the mandibular body. and thyroid gland during the full-mouth periapical radiography. panoramic radiography. and zonography were measured. Resul ts: From the zonography. the absorbed doses to the brain. the skin over the TMJ. and the parotid gland were relatively high. but the absorbed doses to the bone marrow in the mandibular body and. especially. the thyroid gland were very low. Conclusion: The zonography can be an alternative to the full-mouth periapical radiography in aspect of radiation protection.

• Imaging Science in Dentistry
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• v.39 no.4
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• pp.195-198
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• 2009

Purpose : To establish reference doses of periapical radiography in Chonnam Province, Korea. Materials and Methods : The target-skin distances were measured for dental patient's 1235 exposures including 345 mandibular molar areas. Each periapical radiation exposure was simulated with exactly the same patients exposure parameters and the simulated radiation doses were measured utilizing Mult-O-Meter (Unfors Instruments, Billadal, Sweden). The measurements were done in 44 dental clinics with 49 dental x-ray sets in Chonnam Province for one or two weeks at each dental clinic during year 2006. Results : The third quartile patient surface doses were 2.8 mGy for overall periapical exposures and 3.2 mGy for periapical mandibular molar exposures. Conclusion : The third quartile patient surface doses in Chonnam Province can be used as a guide to accepted clinical practice to reduce patient radiation exposure for the surveyed reference doses were below the recommended dental periapical radiography dose of 7 mGy by IAEA.

• Imaging Science in Dentistry
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• v.41 no.4
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• pp.161-165
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• 2011

It is difficult to take intraoral radiographs in some patients who are intolerable to place the film in their mouth. For these patients, Newman and Friedman recommended a new technique of extraoral film placement. Here we report various cases that diagnostic imaging was performed in patients using the extraoral periapical technique. This technique was used to obtain the radiographs for the patients with severe gag reflex, pediatric dental patients, and patients with restricted mouth opening. This technique can be recommended as an alternative to conventional intraoral periapical technique in cases where intraoral film placement is difficult to achieve.

• Journal of Korean society of Dental Hygiene
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• v.12 no.5
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• pp.987-997
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• 2012

Objectives : This study was carried out in order to obtain basic data for students' efficient acquirement and instruction of radiography technology in the future by surveying dental hygiene students' recognition of periapical radiography. Methods : This study carried out a questionnaire survey targeting dental hygiene students from December 2009 to December 2010, and obtained the following results. Results : 1. As a result of examining recognition on periapical radiography, the bisecting angle technique was indicated to be averagely $3.84{\pm}0.566$ points. The paralleling technique was indicated to be $2.66{\pm}0.701$ points. 2. As a result of examining about problems given the bisecting angle technique, what had been most difficult given the bisecting angle technique was indicated to be the highest in cone positioning with 34.2%. The most difficulty given deciding on the X-ray vertical-angel irradiation direction was indicated to be the highest with 66.9% in adjusting the cone direction on the virtual bisector. 3. As a result of examining about problems given the paralleling technique, what had been most difficult in the process of the paralleling technique was indicated to be the highest with 56.7% in fixing the film immobilization device inside the mouth. Conclusions : Examining the above results, it is considered that there is a need of understanding morphological and anatomical structure inside the mouth in order to reduce the mistake rate given the periapical radiography, and that it is important to increase skill level by repetitively shooting several times with having enough time.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.2
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• pp.435-459
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• 1998

In order to achieve a successful endodontic treatment, root canals must be obturated three-dimensionally without causing any damage to apical tissues. Accurate length determination of the root canal is critical in this case. For this reason, I've used the conventional periapical radiography, Digora/sup (R)/(digital imaging system) and Root ZX/sup (R)/(the frequency dependent type apex locator) to measure the length of the canal and compare it with the true length obtained by cutting the tooth in half and measuring the length between the occlusal surface and the apical foramen. From the information obtained by these measurements, I was able to evaluate the accuracy and clinical usefulness of each systems. whether the thickness of files used in endodontic therapy has any effect on the measuring systems was also evaluated in an effort to simplify the treatment planning phase of endodontic treatment. 29 canals of 29 sound premolars were measured with #15, #20, #25 files by 3 different dentists each using the periapical radiography. Digora/sup (R)/ and Root ZX/sup (R)/. The measurements were then compared with the true length. The results were as follows: 1. In comparing mean discrepancies between measurements obtained by using periapical radiography(mean error: -0.449±0.444 mm), Digora/sup (R)/(mean error: -0.417±0.415 mm) and Root ZX/sup (R)/(mean error: 0.123±0.458 mm) with true length. periapical radiography and Digora/sup (R)/ system had statistically significant differences(p<0.05) in most cases while Root ZX/sup (R)/ showed none(p>0.05). 2. By subtracting values obtained by using periapical radiography, Digora/sup (R)/ and Root ZX/sup (R)/ from the true length and making a distribution table of their absolute values. the following analysis was possible. In the case of periapical film. 140 out of 261<53.6％) were clinically acceptable satisfying the margin of error of less than 0.5 mm. 151 out of 261 (53,6％) were acceptable in the Digora/sup (R)/ system while Root ZX/sup (R)/ had 197 out of 261(75.5％) within the limits of 0.5mm margin of error. 3. In determining whether the thickness of files has any effect on measuring methoths, no statistically significant differences were found(p>0.05). 4. In comparing data obtained from these methods in order to evaluate the difference among measuring methods, there was no statistically significant difference between periapical radiography and Digora/sup (R)/ system(p>0.05), but there was statistically significant difference between Root ZX/sup (R)/ and periapical radiography(p<0.05). Also there was statistically significant difference between Root ZX/sup (R)/ and Digora/sup (R)/ system(p<0.05). In conclusion, Root ZX/sup (R)/ was more accurate when compared with the Digora/sup (R)/ system and periapical radiography and seems to be more effective clinically in determining root canal length. But Root ZX/sup (R)/ has its limits in determining root morphology and number of roots and its accuracy becomes questionable when apical foramen is open due to unknown reasons. Therefore the combined use of Root ZX/sup (R)/ and the periapical radiography are mandatory. Digora/sup (R)/ system seems to be more effective when periapical radiographs are needed in a short period of time because of its short processing time and less exposure.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.233-238
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• 2014

Purpose: A method detecting change of jaw or alveolar bone density may be helpful in periodontal care, implant dentistry and evaluation of bone density of whole body. Materials and methods: In this study, bone density of intraoral periapical radiography using phantom-integrated XCP is compared with that of quantitative computed tomography (QCT). Results: Bone density of intraoral periapical radiography and the one measured by QCT showed high correlation (correlation coefficient = 0.92, P<.001) in alveolar bone, and relatively high correlation (0.73, P<.001) in cancellous bone. Conclusion: This study revealed possibility of scoring of bone density by intraoral periapical radiography.

• Imaging Science in Dentistry
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• v.44 no.2
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• pp.115-119
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• 2014

Purpose: The aim of this in vitro study was to determine the sensitivity and specificity of cone-beam computed tomography (CBCT) and digital periapical radiography in the detection of mesial root perforations of mandibular molars. Materials and Methods: In this in vitro study, 48 mandibular molars were divided into 4 groups. First, the mesial canals of all the 48 teeth were endodontically prepared. In 2 groups (24 teeth each), the roots were axially perforated in the mesiolingual canal 1-3 mm below the furcation region, penetrating the root surface ("root perforation"). Then, in one of these 2 groups, the mesial canals were filled with gutta-percha and AH26 sealer. Mesial canals in one of the other 2 groups without perforation (control groups) were filled with the same materials. The CBCT and periapical radiographs with 3 different angulations were evaluated by 2 oral and maxillofacial radiologists. The specificity and sensitivity of the two methods were calculated, and P<0.05 was considered significant. Results: The sensitivity and specificity of CBCT scans in the detection of obturated root canal perforations were 79% and 96%, respectively, and in the case of three-angled periapical radiographs, they were 92% and 100%, respectively. In non-obturated root canals, the sensitivity and specificity of CBCT scans in perforation detection were 92% and 100%, respectively, and for three-angled periapical radiographs, they were 50% and 96%, respectively. Conclusion: For perforation detection in filled-root canals, periapical radiography with three different horizontal angulations would be trustworthy, but it is recommended that CBCT be used for perforation detection before obturating root canals.

• Imaging Science in Dentistry
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• v.35 no.4
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• pp.203-205
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• 2005

Purpose: This study was aimed to compare skin entrance dose of digital radiography with that of film radiography and to show the dose reduction achievement with digital systems at 11 dental schools in Korea. Materials and Methods: Forty six intraoral radiographic systems in 11 dental schools were included in this study. Digital sensors were used in 33 systems and film was used in 13 systems. Researchers and the volunteer visited 11 dental schools in Korea. Researchers asked the radiologic technician (s) at each school to set the exposure parameters and aiming the x-ray tube for the periapical view of the mandibular molar of the volunteer. The skin entrance doses were measured at the same exposure parameters and distance by the technician for each system with a dosimeter (Multi-O-Meter : Unfors instruments, Billdal, Sweden). Results: The median dose was $491.2{\mu}Gy$ for digital radiography and $1,205.0{\mu}Gy$ for film radiography. The skin entrance dose in digital radiography was significantly lower than that of film radiography (p<0.05). Conclusion: Fifty-nine percent skin entrance dose reduction with digital periapical radiography was achieved over the film radiography in Korean dental schools.