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Justification for computed tomography scanning
READERS' FORUM
Letters to the editor* Justification for computed tomography scanning e read the article titled “Interdisciplinary treatment for an adult with a unilateral cleft lip and palate” (Ma QL, Conley RS, Wu T, Li H. Am J Orthod Dentofacial Orthop 2014;146:238-48) with great interest, and really appreciate the combined efforts of the team that produced a good esthetic result for the cleft patient. But we are very curious to know the indication for taking a computed tomography scan. The periapical and panoramic radiographs clearly demonstrate the difference in the cleft size from pretreatment to posttreatment. Considering its high radiation dose, a computed tomography scan would be justified only if diagnostically warranted.1 Furthermore, the authors mentioned that the “panoramic radiograph. showed a wide alveolar cleft between the maxillary left central incisor and the canine” but failed to address this issue by secondary bone grafting. Therefore, neither cleft surgery nor implant placement necessitated a computed tomography scan; as a cleft lip and palate patient, the patient would have already undergone multiple radiographic exposures from childhood, so why add to his exposure burden?
W
Soumya Narayani Thirumoorthy Saumiya Gopal Thiruvananthapuram, Kerala, India Am J Orthod Dentofacial Orthop 2015;147:420 0889-5406/$36.00 Copyright Ó 2015 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2015.01.006
REFERENCE
an oral surgeon for alveolar bone grafting. The oral surgeon asked the patient to have a computed tomography scan for following reasons: (1) the patient and his parents were worried about the risk and success rate of the surgery, (2) the oral surgeon could better evaluate the space of the maxillary alveolar cleft with a computed tomography scan from 3 dimensions, (3) the maxilla could be fully observed during expansion because of the wide alveolar cleft, and (4) there was no conebeam computed tomography in the hospital at that time. Before taking a computed tomography scan, the patient was informed about the high radiation dose, and he agreed to have the scan. He and his family didn't want to go to other places for cone-beam computed tomography as well. During the computed tomography scan, we took as many precautions as possible. Huang Li Nanjing, China Am J Orthod Dentofacial Orthop 2015;147:420 0889-5406/$36.00 Copyright Ó 2015 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2015.01.005
Effectiveness of 3 methods of anchorage reinforcement
A
fter a discussion in our Journal Club of a recent article (Sandler J, Murray A, Thiruvenkatachari B, Gutierrez R, Speight P, O'Brien K. Effectiveness of 3 methods of anchorage reinforcement for maximum anchorage in adolescents: a 3-arm multicenter randomized clinical trial. Am J Orthod Dentofacial Orthop 2014;146:10-20), we have some questions. 1.
1. Brenner DJ, Hall EJ. Computed tomography: an increasing source of radiation exposure. N Engl J Med 2007;357:2277-84.
Author's response
W
e appreciate the great attention of Drs Soumya Narayani Thirumoorthy and Saumiya Gopal to our case. Before orthodontic treatment, the panoramic radiograph showed a maxillary alveolar cleft. During the orthodontic treatment, the maxillary arch needed to be expanded, so we advised the patient to consult
*The viewpoints expressed are solely those of the author(s) and do not reflect those of the editor(s), publisher(s), or Association.
420
2.
The sample size calculation of the study was based on a previous study that used a standard deviation of 1.8 mm for net molar movement relative to basal bone.1 In the current study, the largest standard deviation was 2.09 mm for the maxillary left molar movement in the headgear group. Since the standard deviation was larger than that in the original sample size calculation, did the authors consider a post hoc sample size calculation to determine whether the sample size was still appropriate? Regarding the area for maxillary superimposition, the authors selected “the blue mushroom-shaped area based on the palatal rugae and a stable area of the hard palate.” However, according to a
Letters to the editor* Justification for computed tomography scanning e read the article titled “Interdisciplinary treatment for an adult with a unilateral cleft lip and palate” (Ma QL, Conley RS, Wu T, Li H. Am J Orthod Dentofacial Orthop 2014;146:238-48) with great interest, and really appreciate the combined efforts of the team that produced a good esthetic result for the cleft patient. But we are very curious to know the indication for taking a computed tomography scan. The periapical and panoramic radiographs clearly demonstrate the difference in the cleft size from pretreatment to posttreatment. Considering its high radiation dose, a computed tomography scan would be justified only if diagnostically warranted.1 Furthermore, the authors mentioned that the “panoramic radiograph. showed a wide alveolar cleft between the maxillary left central incisor and the canine” but failed to address this issue by secondary bone grafting. Therefore, neither cleft surgery nor implant placement necessitated a computed tomography scan; as a cleft lip and palate patient, the patient would have already undergone multiple radiographic exposures from childhood, so why add to his exposure burden?
W
Soumya Narayani Thirumoorthy Saumiya Gopal Thiruvananthapuram, Kerala, India Am J Orthod Dentofacial Orthop 2015;147:420 0889-5406/$36.00 Copyright Ó 2015 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2015.01.006
REFERENCE
an oral surgeon for alveolar bone grafting. The oral surgeon asked the patient to have a computed tomography scan for following reasons: (1) the patient and his parents were worried about the risk and success rate of the surgery, (2) the oral surgeon could better evaluate the space of the maxillary alveolar cleft with a computed tomography scan from 3 dimensions, (3) the maxilla could be fully observed during expansion because of the wide alveolar cleft, and (4) there was no conebeam computed tomography in the hospital at that time. Before taking a computed tomography scan, the patient was informed about the high radiation dose, and he agreed to have the scan. He and his family didn't want to go to other places for cone-beam computed tomography as well. During the computed tomography scan, we took as many precautions as possible. Huang Li Nanjing, China Am J Orthod Dentofacial Orthop 2015;147:420 0889-5406/$36.00 Copyright Ó 2015 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2015.01.005
Effectiveness of 3 methods of anchorage reinforcement
A
fter a discussion in our Journal Club of a recent article (Sandler J, Murray A, Thiruvenkatachari B, Gutierrez R, Speight P, O'Brien K. Effectiveness of 3 methods of anchorage reinforcement for maximum anchorage in adolescents: a 3-arm multicenter randomized clinical trial. Am J Orthod Dentofacial Orthop 2014;146:10-20), we have some questions. 1.
1. Brenner DJ, Hall EJ. Computed tomography: an increasing source of radiation exposure. N Engl J Med 2007;357:2277-84.
Author's response
W
e appreciate the great attention of Drs Soumya Narayani Thirumoorthy and Saumiya Gopal to our case. Before orthodontic treatment, the panoramic radiograph showed a maxillary alveolar cleft. During the orthodontic treatment, the maxillary arch needed to be expanded, so we advised the patient to consult
*The viewpoints expressed are solely those of the author(s) and do not reflect those of the editor(s), publisher(s), or Association.
420
2.
The sample size calculation of the study was based on a previous study that used a standard deviation of 1.8 mm for net molar movement relative to basal bone.1 In the current study, the largest standard deviation was 2.09 mm for the maxillary left molar movement in the headgear group. Since the standard deviation was larger than that in the original sample size calculation, did the authors consider a post hoc sample size calculation to determine whether the sample size was still appropriate? Regarding the area for maxillary superimposition, the authors selected “the blue mushroom-shaped area based on the palatal rugae and a stable area of the hard palate.” However, according to a