Authors' response.

Abstract

We want to thank you for your valuable comments on our article (El-Timamy AM, El-Sharaby FA, Eid FH, Mostafa YA. Three-dimensional imaging for indirect-direct bonding. Am J Orthod Dentofacial Orthop 2016;149:928-31). Interest in cone-beam computed tomography (CBCT) from all fields of dentistry is currently unprecedented, particularly since third-party software applications have expanded the role of imaging from diagnosis to image guidance of operative and surgical procedures. Since its implementation in orthodontics, CBCT imaging has experienced a great enhancement, which up until now did not justify its use as a routine pretreatment diagnostic tool, especially for children. This is mainly due to 2 major flaws: radiation dose and metallic artifacts. Accordingly, we totally agree that using this technique in contemporary CBCT machines would be indefensible. However, the main intent of our article was to introduce a novel technique for bracket positioning that could be adopted if acceptable CBCT exposure parameters can be attained in the future. Despite the fact that the results were less than optimum, the 3D models for the brackets in our article were obtained through CBCT scanning. The images were satisfactory for the presented technique of bonding. Yet, in a project we are working on now, a more enhanced and reliable 3D bracket model has been obtained using laser scanning technology. As we mentioned in our article, having 3D images of brackets from different manufacturers could facilitate their implementation for virtual bonding with this technique without prior need for their 3D scanning step. Computer-aided bracket positioning presented in our article requires an accurate 3D virtual model of dental structures and occlusion. Unfortunately, the major obstacle with CBCT imaging is that it cannot provide detailed dental surface morphology and accurate interocclusal relationships, owing to the limited scanning resolution and streak artifacts caused by radiopaque dental restorations. Although it was not mentioned in the published article, this problem was overcome by substituting the dental portion of 3D CBCT images with precise dental images of an orthodontic 3D digital model. Surface superimposition was based on the palatal vault and the medial portions of the palatal rugae by surface-to-surface matching (best-fit method).1Lebret L. Growth changes of the palate.J Dent Res. 1962; 41: 1391-1404Crossref Scopus (48) Google Scholar, 2Almeida M.A. Phillips C. Kula K. Tulloch C. Stability of the palatal rugae as landmarks for analysis of dental casts.Angle Orthod. 1995; 65: 43-48PubMed Google Scholar This method has proved to be simple, reproducible, and reliable.3Park T.J. Lee S.H. Lee K.S. A method for mandibular dental arch superimposition using 3D cone beam CT and orthodontic 3D digital model.Korean J Orthod. 2012; 42: 169-181Crossref PubMed Scopus (34) Google Scholar Moreover, the accuracy of the integration of laser-scanned dental models into CBCT images was reported to be higher with a high threshold setting in 0.20 to 0.40-mm voxel sizes.4Ye N. Long H. Xue J. Wang S. Yang X. Lai W. Integration accuracy of laser-scanned dental models into maxillofacial cone beam computed tomography images of different voxel sizes with different segmentation threshold settings.Oral Surg Oral Med Oral Pathol Oral Radiol. 2014; 117: 780-786Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar Ethical considerations of 3-dimensional imagingAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 151Issue 1PreviewWe read with interest the article on 3-dimensional (3D) imaging for indirect-direct bonding in the June issue (El-Timamy AM, El-Sharaby FA, Eid FH, Mostafa YA. Three-dimensional imaging for indirect-direct bonding. Am J Orthod Dentofacial Orthop 2016;49:928-31). It stated that clinicians could be influenced by many factors during bracket placement, and the authors suggested using 3D imaging and printers to avoid problems. However, the ethical limitations in taking CBCT records are obstacles for using the method in routine clinical practice (there are exceptions such as impacted teeth, and severe skeletal anomalies). Full-Text PDF