We appreciate the interest of Drs Ye, Li, and Lai in the controversial topic of airway volume assessment with CBCT. Below are our responses to their questions.
The aim of our study was the comparison between the scanned and actual volumes from the prototype airway. The choice of a negative prototype to create an airway model was because the Dolphin software only allows the volume measurement of empty areas. We did not expect to mimic the soft tissues surrounding the airway.
We did not intend to establish a protocol for airway assessment but to determine the most accurate threshold for airway volume calculation with specific experimental conditions. So, it was not our objective to extend our results to the measurement of in-vivo CBCT scans but to raise the question of the great difference that can arise from volume calculations with different thresholds. Unfortunately, it is not possible to do this research in humans.
The description of the scan protocol (milliamperes, kilovolts) used by CBCT machines is important in studies that evaluate airway volume. Several studies have evaluated airway volumes with different CBCT machines. Therefore, we emphasized in the discussion that our study was based on specific experimental conditions.
For this investigation, we used only 1 subject to obtain the airway prototype. Future investigations about the comparison between the airway volumes from several subjects and the actual volumes of the prototypes obtained from these subjects will allow the establishment of the most appropriate threshold value to use with Dolphin software for airway volume assessment.
- 1. Tso H.H., Lee J.S., Huang J.C., Maki K., Hatcher D., and Miller A.J.: Evaluation of the human airway using cone-beam computerized tomography. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: pp. 768-776
- 2. Aboudara C., Nielsen I., Huang J.C., Maki K., Miller A.J., and Hatcher D.: Comparison of airway space with conventional lateral headfilms and 3-dimensional reconstruction from cone-beam computed tomography. Am J Orthod Dentofacial Orthop 2009; 135: pp. 468-479
- 3. Grauer D., Cevidanes L.S.H., Styner M.A., Ackerman J.L., and Proffit W.R.: Pharyngeal airway volume and shape from cone-beam computed tomography: relationship to facial morphology. Am J Orthod Dentofacial Orthop 2009; 136: pp. 805-814
- 4. Haskell J.A., McCrillis J., Haskell B.S., Scheetz J.P., Scarfe W.C., and Farman A.G.: Effects of mandibular advancement device (MAD) on airway dimensions assessed with cone-beam computed tomography. Semin Orthod 2009; 15: pp. 132-158
- 5. Iwasaki T., Hayasaki H., Takemoto Y., Kanomi R., and Yamasaki Y.: Oropharyngeal airway in children with Class III malocclusion evaluated by cone-beam computed tomography. Am J Orthod Dentofacial Orthop 2009; 136: pp. 318.e1-318.e9
- 6. Lohse A.K., Scarfe W.C., Shaib F., and Farman A.G.: Obstructive sleep apnea-hypopnea syndrome: clinical applications of cone beam CT. Australas Dent Pract 2009; 20: pp. 104-114
- 7. Kim Y.J., Hong J.S., Hwang Y.I., and Park Y.H.: Three-dimensional analysis of pharyngeal airway in preadolescent children with different anteroposterior skeletal patterns. Am J Orthod Dentofacial Orthop 2010; 137: pp. 306.e1-306.e11
- 8. El H., and Palomo J.M.: Measuring the airway in 3 dimensions: a reliability and accuracy study. Am J Orthod Dentofacial Orthop 2010; 137: pp. S50.e1-S50.e9
- 9. Zinsly S.R., Moraes L.C., Moura P., and Ursi W.: Assessment of pharyngeal airway space using cone-beam computed tomography. Dent Press J Orthod 2010; 15: pp. 150-158
- 10. Iwasaki T., Saitoh I., Takemoto Y., Inada E., Kanomi R., Hayasaki H., et al: Evaluation of upper airway obstruction in Class II children with fluid-mechanical simulation. Am J Orthod Dentofacial Orthop 2011; 139: pp. e135-e145
- 11. Iannetti G., Polimeni A., Pagnoni M., Fadda M.T., Ranieri V., Tecco S., et al: Upper airway volume after Le Fort III advancement in subjects with craniofacial malformation. J Craniofac Surg 2011; 22: pp. 351-355
- 12. Alves M., Baratieri C., Nojima L.I., Nojima M.C., and Ruellas A.C.: Three dimensional assessment of pharyngeal airway in nasal- and mouth-breathing children. Int J Pediatr Otorhinolaryngol 2011; 75: pp. 1195-1199