Using 3-Dimensional Printing to Create Presurgical Models for Endodontic Surgery
Advances in endodontic surgery—from both a technological and procedural perspective—have been significant over the last 18 years. Although these technologies and procedural enhancements have significantly improved endodontic surgical treatment outcomes, there is still an ongoing challenge of overcoming the limitations of interpreting preoperative 2-dimensional (2-D) radiographic representation of a 3-dimensional (3-D) in vivo surgical field. Cone-beam Computed Tomography (CBCT) has helped to address this issue by providing a 3-D enhancement of the 2-D radiograph. The next logical step to further improve a presurgical case 3-D assessment is to create a surgical model from the CBCT scan. The purpose of this article is to introduce 3-D printing of CBCT scans for creating presurgical models for endodontic surgery.
There have been significant endodontic surgical advancements over the last 18 years. The use of magnification (eg, surgical operating microscope and endoscope), ultrasonic tips for root-end preparation, microinstruments and retrofill materials (other than amalgam) have been a few of the changes that have taken place during this time.1-3 As with any change in health care delivery, one must evaluate if these changes provide a better treatment outcome for the patient. A study by Tsesis concluded that surgical endodontic treatment performed with microsurgical techniques has a more successful outcome than using past surgical techniques.4
Presurgical Case Assessment
Before performing any endodontic surgical procedure, there are a number of steps that need to be completed. These steps include ensuring that the surgical tooth is properly restored, conventional re-treatment on the surgical tooth if indicated, evaluating the thickness of the bone at the surgical access, and taking radiographs (eg, periapical, panoramic, bite wing, and/or cone-beam computed tomography [CBCT]) of the surgical region.5
The ongoing challenge of any endodontic surgical procedure is the ability to process the information gained from interpreting 2-dimensional (2-D) radiographic representation of a 3-dimensional (3-D) in vivo surgical field. The introduction of CBCT in endodontic surgery helps to provide a more 3-D view of a surgical site.6 CBCT produces 3-D scans and is an excellent instrument for overcoming the limitations of conventional dental radiographs.7
Although CBCT provides major advantages over conventional dental radiographs, taking this technology to the next level by converting a CBCT scan to a 3-D model by using 3-D printing can greatly enhance a dentist’s ability to understand preoperative surgical anatomy in “true” 3-D.
Printing in 3-D is the process of making a 3-D solid object from a digital model, and is an additive process. This process is achieved when successive layers of material are laid down in different shapes, whereas traditional modeling relies on the removal of material by methods such as cutting or drilling.8
Although the commercial interest in 3-D printing is recent, the development of this technology dates back three decades to Japanese researchers, who printed the first 3-D object. In 1984, Charles W. Hall patented “sterolithography.” This allowed the ability to generate 3-D objects by creating cross-sectional patterns of the object to be formed.9-11
The Use of 3-Dimensional Printing in Endodontic Surgery
Although a current review of the literature does not find any reports of 3-D printing in clinical conventional or surgical endodontics, there are literature reports of 3-D printing in the fields of oral and maxillofacial surgery and implant dentistry.12-15
Creating a presurgical model of an endodontic surgical site requires the patient to have a CBCT scan of the treatment region. It is recommended to use a limited-volume CBCT unit with variable fields of view (FoVs) as compared to a large-volume CBCT scanner. The limited-volume CBCT scan allows the visualization of 2 to 3 teeth, whereas the large-volume CBCT scan captures the entire maxillofacial skeleton.16 All CBCT images should be saved in a Digital Imaging and Communications in Medicine (DICOM) format.
To print the CBCT scan image in 3-D, the DICOM file needs to be converted to a stereolithography (.stl) file. This file conversion can be performed through various software applications available on the market. After the file is converted into a .stl file, it can then be sent to the 3-D printer (Figure 1). Printing time will vary depending on the size of the surgical model being produced. The material used to create the presurgical model is plastic. The clinical advantage of a presurgical model is it enables the dentist to touch, feel, and visualize the surgery field in “true” 3-D as if it was in vivo.
Current advances in endodontic surgery have been a result of changes in procedure and technology. Although these advancements have improved the surgical treatment outcome, presurgical case assessment is still hampered by the limitation of interpreting 2-D radiographic representation of a 3-D in vivo surgical field. The recent integration of CBCT technology in the field of endodontics has significantly improved the 3-D imaging of the 2-D radiograph. The ability to transform the CBCT image into a presurgical model through 3-D printing provides a “true” 3-D model of an in vivo endodontic surgical site.
ABOUT THE AUTHOR
James K. Bahcall, DMD, MS
Professor, Midwestern University College of Dental Medicine, Downers Grove, Illinois; Diplomate, American Board of Endodontics
1. Kim S. Principles of endodontic surgery. Dent Clin North Am. 1997;41(3):481-497.
2. Bahcall JK, DiFiore PM, Poulakidas TK. An endoscopic technique for endodontic surgery. J Endod. 1999;25(2):132-135.
3. Rubinstein R, Torabinejad M. Contemporary endodontic surgery. J Calif Dent Assoc. 2004;32(6):485-492.
4. Tsesis I, Rosen E, Taschieri S, et al. Outcomes of surgical endodontic treatment performed by a modern technique: an updated meta-analysis of the literature. J Endod. 2013;39(3):332-339.
5. Bahcall JK. Everything I know about endodontic surgery I learned after graduate school. Dent Today. 2004;23(8):72, 74-77.
6. Shekhar V, Shashikala K. Cone beam computed tomography evaluation of the diagnosis, treatment planning, and long-term follow up of large periapical lesions treated by endodontic surgery: two case reports. Case Rep Dent. 2013;2013:564392.
7. Patel S, Kanagasingam S, Mannocci F. Cone beam computed tomography (CBCT) in endodontics. Dent Update. 2010;37(6):373-379.
8. Excell J, Nathan S. The rise of additive manufacturing. The Engineer Web site. http://www.theengineer.co.uk/in-depth/the-big-story/the-rise-of-additive-manufacturing/1002560.article. Accessed January 28, 2014.
9. Freedman DH. Layer by layer. MIT Technology Review Web site. http://www.technologyreview.com/featuredstory/426391/layer-by-layer/. Accessed January, 28 2014.
10. Daly J. The History of 3D Printing. StateTech Wesbite. http://www.statetechmagazine.com/article/2013/08/history-3d-printing-infographic. Accessed January 28, 2014.
11. Hsu J. 3D Printing: What a 3D Printer Is and How It Works. LiveScience Website. http://www.livescience.com/34551-3d-printing.html. Accessed January 28, 2014.
12. Metzger MC, Hohlweg-Majert B, Schwarz U, et al. Manufacturing splints for orthognathic surgery using a three-dimensional printer. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008;105(2): e1-7.
13. Cohen A, Laviv A, Berman P, et al. Mandibular reconstruction using sterolithographic 3-dimensional printing modeling technology. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108(5):661-666.
14. Dai J, Wang X, Dong Y, et al. Two- and three-dimensional models for the visualization of jaw tumors based on CT-MRI image fusion. J Craniofac Surg. 2012;23(2):502-508.
15. Flügge TV, Nelson K, Schmelzeisen R, Metzger MC. Three-dimensional plotting and printing of an implant drilling guide: simplifying guided implant surgery. J Oral Maxillofac Surg. 2013;71(8):1340-1346.
16. Edlund M, Nair M, Nair UP. Detection of vertical root fractures by using cone-beam computed tomography: a clinical study. J Endod. 2011;37(6):768-772.