The role of 3D printing in ENT surgery

Introduction

Three-dimensional (3D) printing is a rapidly growing technology, with numerous applications in Otolaryngology and Head and Neck Surgery. Since its conception in the 1980s, 3D printing—also known as rapid prototyping, solid-freeform technology or additive manufacturing—technology and 3D printing equipment have improved and are less expensive; the expertise is more widespread, and therefore, it has been available in many parts of the world for medical use in several fields .

The concept of three-dimensional printing was introduced by C. Hull in 1986, and it was initially defined as an “apparatus for production of three-dimensional objects by stereolithography” . As it is known, rapid prototyping involved the construction of three-dimensional models by gradually layering material . The exact technology of 3D printing is still evolving and nowadays the ASTM International Committee F42 has described seven subcategories of 3D printing methodology, as shown in Table 11.1 [6] . All of them have their basis on the original principle of the .STL format (Standard Triangulation Language) which was developed by C. Hull in the 1980s and practically makes it possible to convert the surface of a three-dimensional object to triangles. There are several ways to obtain a .STL file format, such as DICOM data (digital imaging and communication in medicine) from CT or MRI scans, CAD (computer-aided design) software, or by scanning the actual object with an appropriate scanning device .

Apart from the subcategory classification in Table 11.1 , it is worth mentioning the available technologies and the materials used, aiming to give an impression of the potential medical applications ( Table 11.2 ). More detailed technical specifications and advantages/disadvantages are outside the scope of this chapter and therefore not analyzed in depth.

Applications in otolaryngology

Several articles can be found in the literature on the applications of 3D printing in Otolaryngology. These can be categorized according to the relevant subspecialty (Otology, Rhinology, Pediatric Otolaryngology, Head and Neck Surgery/Laryngology) but also according to the proposed application. Thus, the 3D-printed models can be used in perioperative planning, patient education, surgical training, grafting, prosthetics, and reconstruction. A recent systematic review by Canzi et al. (2018) looked at 121 studies, with the majority of them focusing on perioperative planning and surgical training. It is also worth mentioning that this study demonstrated that most of the Head and Neck studies were relevant to preoperative planning, while ontological studies focused mainly on surgical training in terms of temporal bone dissection. Rhinology-related studies were fewer, and most of them had to do with surgical training. The same review article also demonstrated the chronological distribution of the relevant publications and also the different printing methodologies ( Figs. 11.1 and 11.2 ) .