| dcterms.abstract | Ectopic eruption and impaction of the permanent maxillary canines represent a significant problem of dental development, occurring in 1% to 3% of the population. Careful observation of the development and eruption of maxillary canines is necessary in growing patients as canine impaction can result in serious sequelae to the dentition. A major sequela associated with impaction of maxillary canines is external root resorption of neighboring teeth. Root resorption is often clinically asymptomatic and mainly discovered during radiographic examination. Accurate diagnosis of canine position and detection of possible root resorption of adjacent teeth can significantly impact the orthodontic-surgical treatment planning. The successful management of impacted maxillary canines and possible root resorption of adjacent teeth involves accurate prediction and diagnosis along with proper timing of intervention. The purpose of this study was to measure juvenile radiation dose to organs of the head and neck in radiographic examination of root resorption associated with impacted maxillary canines during two-dimensional digital radiographic techniques and three-dimensional cone-beam tomographic scans using anthromorphic CIRS phantom at 10-years-old with nanoDot optically stimulated luminescent dosimeters (OSLDs). A juvenile anthropomorphic phantom (model 705; Computerized Imaging Reference System (CIRS), Norfolk, Va) corresponding to a 10-year-old male was used for all exposures. OSLDs were placed at 21 head and neck organ sites of the phantom head. The following devices were tested: Gendex Export OC, Sirona Orthophos XG, Carestream Kodak 9000 3D, i-CAT Platinum, and Instrumentarium Orthopantomograph OP300 Maxio. For all scans, the preset pediatric scan settings representing those used typically for orthodontic imaging were used and when available, the field of view selected was to image the anterior maxilla, capturing the maxillary canines and its neighboring teeth (incisors and first premolars). The scans were performed with and without applying lead glasses and thyroid collar shield. The effective radiation dose was calculated for the organs of the head and neck. All scans were repeated three times and the results averaged. Organ fractions irradiated were determined from ICRP-89. Overall effective doses were calculated in microSieverts for the averaged results and based on the ICRP-103 tissue weighting factors. Overall measured organ doses and the effective doses were higher for the CBCT scans than for the digital intraoral periapical and panoramic radiographs. The effective doses measured with panoramic radiographs were significantly less when compared to CBCT scans. The highest organ dose exposures were in the salivary glands, oral mucosa, and extrathoracic airway. The use of leaded glasses and thyroid collar resulted in dose reduction of 24.4 - 25% with the Sirona Orthophos XG, Kodak 9000 3D machine and Instrumentarium OP300 at standard resolution. This was the first study to evaluate radiation exposure to a 10-year-old juvenile CIRS phantom using OSL dot dosimetry in conjunction with leaded glasses and thyroid shield, utilizing two and three dimensional imaging for orthodontic purposes. CBCT, although recognized for superior diagnostic benefits, had higher levels of radiation than conventional two-dimensional digital radiography. Following the ALARA principle, restricting the field of view to anterior maxilla can allow CBCT imaging to be used with young patients in specific and justified clinical situations when three-dimensional assessment of the presence and severity of root resorption is necessary. When such imaging is prescribed, the recommendation would be to use a narrow-field CBCT imaging machine with the proper use of radiation shielding equipment. | |
