Abstract




3D printing systems have revolutionised prototyping in the industrial field by lowering production time from days to hours and costs from thousands to just a few dollars. Today, 3D printers are no more confined to prototyping, but are increasingly employed in medical disci- plines with fascinating results, even in many aspects of otorhinolaryngology. All publications on ENT surgery, sourced through updated electronic databases (PubMed, MEDLINE, EMBASE) and published up to March 2017, were examined according to PRISMA guidelines. Overall, 121 studies fulfilled specific inclusion criteria and were included in our systematic review. Studies were classified according to the specific field of application (otologic, rhinologic, head and neck) and area of interest (surgical and preclinical education, customised surgical planning, tissue engineering and implantable prosthesis). Technological aspects, clinical implications and limits of 3D printing processes are discussed focusing on current benefits and future perspectives.




Introduction

Around 1450, Gutenberg developed a printing system that became a stepping-stone in the timeline of communication technology, and considered as one of the most influential events in the sharing of scientific and medical knowledge. Since its first introduction in the early 1980s, 3D printing (3DP) technology has rapidly caught the interest of the industry, healthcare and media with an overall business of $700 million 1-4. The nature of all 3D printers is the creation of a wide range of 3D objects obtained from digital data of easy management and available in open-access digital databases, allowing a unique opportunity for information exchange (e.g. 3dprint.nih.gov). Almost anything can be produced by 3DP systems: fuel injectors for rockets, jewels and hearing aid shells 5 6. One of the most fascinating aspects of this technology concerns the employment of imaging studies. Today, radiology plays a pivotal role in diagnostic and therapeutic decision making. However, scans are still displayed on flat screens, resulting in a 2D representation of reality. Surgeons’ experience the difficult task of figuring out a three-dimensional image on a daily basis, by analysing CT or MRI-slices in separate two-dimensional axial, coronal and sagittal projections 7. 3DP systems allow to restore the third dimension that is lacking during visualisation of radiological image data. Along with the production of anatomical models addressed to customised surgical planning, medical teaching and surgical training, research in 3DP has explored the pioneering world of biologic tissue engineering, patient-specific implantation and ultimately of personalised pharmacoprinting. The increasing impact of 3DP processes in the scientific literature has recently involved many aspects of otorhinolaryngology, often followed by great expectations regarding patient care. Up to now, what are the applications of 3DP technologies in ENT surgery? Does this tool provide any substantial benefits in the ENT field? And what about future perspectives? The present work aims to answer these questions by carrying out a systematic review of the literature on the topic, a task that, to the best of our knowledge, has not undertaken previously.

The technology of 3DP systems

3DP is a subset of additive manufacturing (AM) or rapid prototyping in which objects are achieved by gradually layering material, rather than by subtraction from the raw material as is in the case of conventional technologies 8. The main advantages of AM are its flexibility, precision and relative quickness in creating customised physical structures of almost any complex shape in a myriad of materials. Historically, 3DP processes were employed by the manufacturing industry to rapidly produce a representation of a system or a part before final release or commercialisation 9. The 3DP was first conceived by C. Hull in 1986 as an “apparatus for production of three-dimensional objects by stereolithography” 3. During the same year, he also developed the “Standard Triangulation Language” (.STL) file format, which makes it possible to deconstruct the surface of a three-dimensional object in a series of triangles. The .STL file can be obtained from a 3D “Computer-Aided Design” (CAD) software, a medical scan data (e.g. CT scan, MRI), or from existing objects by using point or laser scanners. This virtual model is subsequently sliced into thin 2D layers, which are then sent to the 3D printer. 3DP methodologies differ from one another in the way that materials are deployed and cured 8. Recently, the ASTM International Committee F42 classified 3DP technologies in 7 different working process categories 10 (Fig. 1).

  • Vat photopolymerisation: in this technique a container gets filled with photopolymeric resin. This resin is then hardened by an UV light source.
  • Material jetting: this process resembles inkjet paper printing, since the material is dropped through small diameter nozzles. In this case, the base material is a photopolymeric resin subsequently hardened by a UV lamp.
  • Binder jetting: this method employs a powder base material and a liquid binder. In the build chamber, the powder is spread in equal layers and binder is applied through jet nozzles that “glue” the powder particles together in the shape of a programmed 3D object.
  • Material extrusion: the most widespread and popular 3DP technology on the market. These printers are fed a thermo-plastic filament that gets pushed through a heating chamber: the fused material is moulded and then solidified through cooling, allowing the deposition of successive layers.
  • Powder bed fusion: this technology uses a high-power laser source to fuse small particles of plastic, metal, ceramic or glass powders into a mass that has the desired three-dimensional shape. The laser selectively fuses the powdered material by scanning the cross-sections generated by the 3D modelling program on the surface of a powder bed.
  • Sheet lamination: in this technique sheets of material are bound together through external force. These processes can be further categorised based on the mechanism employed to achieve bonding between layers: gluing or adhesive bonding, thermal bonding, clamping, or ultrasonic welding.
  • Direct energy deposition: this process, mostly used in the high-tech metal industry, enables the creation of parts by melting material as it is being deposited. The 3DP is usually attached to a multi-axis robotic arm composed of a nozzle that deposits metal powder or wire on a surface and an energy source (laser, electron beam or plasma arc) that melts it, forming a solid object.
  • Materials and methods

    All existing articles sourced through updated electronic databases (PubMed, MEDLINE, EMBASE) and published up to March 2017 were examined according to the “Preferred Reporting Items for Systematic Reviews and Meta-analyses” (PRISMA) guidelines 11. The research was conducted using the following keywords: “3D printing OR three dimensional printing AND otorhinolaryngology NOT plastic surgery”, “3D printing OR three dimensional printing AND ENT NOT plastic surgery”, “3D printing OR three dimensional printing AND otology NOT plastic surgery”, “3D printing OR three dimensional printing AND rhinology NOT plastic surgery”, “3D printing OR three dimensional printing AND head neck NOT plastic surgery”, “3D Printing OR three-dimensional printing AND mandible NOT plastic surgery”. Other sources analysed for additional relevant trials were reference lists of previous systematic reviews and evaluated works, journal homepages and publications citing included trials. Furthermore, experts in the field of 3D printing and engineering were contacted to ensure that all relevant studies had been included. Searches were done at all stages, from the initial drafting of the paper to submission of the revised and final version. Works lacking clinical or surgical relevance, such as engineering and bio-engineering publications and those regarding the evaluation of accuracy of the 3DP models were excluded since these are out of the expertise of ENT surgeons. Moreover, papers primarily addressing maxillofacial surgery, plastic surgery, thoracic surgery, neurosurgery and dentistry were also excluded. Exclusion criteria also applied to animal research and studies with ambiguous information regarding the modalities of production and employment of the 3DP methodology. Articles not written in English, review articles, letters, editorials and congress abstracts were omitted as well. All the considered studies were classified according to the specific field of application (otologic, rhinologic, head and neck). Each field was furthermore categorised into three distinct areas of interest: surgical and preclinical education, customised surgical planning and tissue engineering and implantable prostheses.

    Results

    The electronic database search yielded 258 citations and a further 123 articles were identified from additional sources, but after removing duplicates the total number of articles decreased to 278. A total of 157 records were removed as they did not fulfil inclusion criteria. Overall, 121 studies were included in the systematic review (Fig. 2). Figure 3 shows the studies according to the specific field of application (otologic, rhinologic, head and neck) and area of interest (surgical and preclinical education, customised surgical planning, tissue engineering and implantable prostheses). The total number of articles in Figure 3 is 135, and not 121, since 14 articles belong to more than one field of application and/or area of interest. Employed AM technology is summarised in Figure 4 considering the three areas of interest.

    Otologic applications (Table I)

    Surgical and preclinical education 12–34

    Twenty-three studies of the otologic ones (n = 39) involved the surgical and preclinical education area (59.0%) and mostly concerned the field of temporal bone dissection. Since the first report in 199831, technological efforts aimed to overcome the restrictions of the initial 3DP models. These first models, which employed a sole material and a single colour, allowed acceptable anatomical results, but limited haptic and drilling features. The evolution of 3DP systems (e.g. binder jetting) led to greater anatomical fidelity thanks to the employment of multiple colours and materials that are able to reproduce the mechanical properties of trabecular mastoid bone with realistic drilling experience. Moreover, the development of printed models coupled with electronic simulators provided a real-time alert in case of injury to vital structures during dissecting practice 28.

    Customised surgical planning 29 35-49

    The production of patient-specific 3DP temporal bones based on preoperative CT was considered suitable for surgical planning and simulation in five cases of challenging anatomy (e.g. congenital aural atresia, acquired subverted anatomy) and in one case of cochlear implant surgery 29, 35-38. Four papers dealt with the creation of 3DP operative templates to assist surgical positioning of a transcutaneous bone-conduction hearing device 39-42. Finally, six studies were on the combined use of surgical navigation and 3DP technology 43-48. In particular, a Japanese publication described the development of a registration method based on bone-anchored fiducial markers using 3DP templates without requiring a preoperative invasive marking process or additional CT. Since its first publication, this process has been simplified and further improved.

    Tissue engineering and implantable prosthetics 50

    Kozin et al. tested a customised 3DP prosthesis for repair of bony superior canal defects on cadaveric temporal bones, even if clinical uses were not yet reported 50.

    Rhinologic applications (Table II)

    Surgical and preclinical education 51-57

    Four studies focused on the development of 3DP training models for endoscopic sinonasal and skull base surgery 51-54. Medium-high fidelity simulators allowed developing surgical skills in the main endoscopic procedures, including drilling techniques and skull base exposure. Low-cost models were primary limited by the materials employed to mimic human bone as much as possible.

    Customised surgical planning 58–60

    Two studies took advantage of the versatility of 3DP systems to fabricate operative templates tailored on the patient’s anatomy. Daniel et al. produced 3DP cutting guides to design an osteoplastic flap during frontal surgery 59; Onerci Altunay et al. used 3DP templates to fashion septal prosthesis for large irregular septal perforations 58. 3DP endoscopic sinus surgery simulation was carried out in two patients with chronic rhinosinusitis to obtain safer and faster procedures 60.

    Tissue engineering and implantable prosthetics 61

    One child with a craniofacial fibrous dysplasia was submitted to resection and reconstruction of the fronto-orbital region by means of a custom 3DP polyetheretherketone implant resulting in good aesthetical and safe outcomes.

    Head and neck applications (Table III)

    Surgical and preclinical education 62–66:

    Two studies focused on resident training for laryngeal surgical procedures. In 2014, Ainsworth et al. created a laryngeal model, including the extra-laryngeal soft tissues, to simulate trans-cervical injection of vocal folds 64. More recently, Kavanagh et al. developed a 3DP paediatric laryngeal model reproducing several challenging surgical conditions (e.g. subglottic cysts, laryngomalacia, subglottic stenosis and laryngeal clefts) 62.

    Customised surgical planning 54 65 67-132

    This was the most frequent ENT application of 3DP technology and mentioned in 68 of the 121 papers (56.2%). Among these, 95.6% of studies (65 out of 68) 54 67-130 concerned surgical management of head and neck tumours requiring mandibular resection and/or reconstruction. The first date to the ’90s and dealt with creation of 3DP mandibles to allow a direct handling of the neoplastic lesion, leading to the early surgical resection simulators. However, the most relevant contribution concerned the reconstructive aspects of oncologic surgery, guiding the employment of plates or autografts. Patient-specific 3DP mandibles were developed to “pre-bent” plates preoperatively. More recently, the introduction of image-guide systems used to plan the harvest and positioning of autografts (e.g. fibula flap, iliac crest bone flap) has led to the production of self-fabricated customised 3DP cutting guides. Many authors experienced a decrease in surgical time and the risk of undesirable events during reconstructive approaches, which resulted in a proper mandibular function. Concerning AM technology, in 38.2% of the studies (26 of 68) the AM category was not specified, mainly due to the outsourcing of all 3D printing operations to external services, which are becoming more common in recent years.

    Tissue engineering and implantable prosthetics 68 70 77 78 88 94 96-98 113 128

    This area included 9.1% of all studies (11 of 121). All these investigations dealt with mandibular reconstruction following tumour resection in a total of 33 patients. The authors employed 3DP technology to develop patient-specific reconstruction plates, trays, meshes and mandibular implants. Titanium alloys (e.g. Ti6Al4V) were used in all cases due to their suitable physical and mechanical properties: low specific weight, corrosion resistance and good biocompatibility 96. 3DP reconstruction plates, tray and meshes were associated with a bone autograft in 9 studies: 66.6% opted for a fibula free flap 77 78 94 96-98 and 33.3% for an iliac crest free flap 68 113 128. Differently, Lee et al. made use of a mandibular implant without the support of a bone autograft, proving an acceptable alternative in cases of unsuitable free flap surgery 70. A total of 27 patients (81.9%) showed good aesthetical and occlusion outcomes and thus correct oral rehabilitation 68 70 77 78 88 94 96 97 113 128. Complications were observed in 2 subjects (6%): one patient experienced bone resorption and infection, while the other had flap necrosis 77 113. The authors reported a reduction of the operating time between 30 98 and 120 minutes 94, enabling economic benefits at the expense of the additional cost of the 3DP prosthesis.

    Discussion

    Personalised medicine, minimally-invasive surgery, tissue engineering and regenerative medicine are the watchwords of third millennium healthcare. The arising popularity around the world of 3DP systems may be explained through the opportunities offered by this new technology to support new trends in modern medicine. Since its first applications in the early 1990s, researchers have explored the advantages of 3D printers, publishing 121 studies in otorhinolaryngology (Fig. 2). Customised surgical planning was evaluated in 71.9% of studies, proving to be the main direction of investigation (Fig. 3). The manufacture of anatomical models before surgery allowed both the understanding of specific anomalies and guidance for the operative strategy. The first and most frequently explored clinical application was resection and reconstruction of oro-mandibular tumours due to their easier medical image processing in comparison with other fields. The development of 3DP operative templates for cutting and/or reconstruction guides minimised the surgeon’s fatigue and complication rates, and optimised the operating room time, which led to lower morbidity. Similar approaches have been employed for complex cases of temporal bone and sinonasal surgery.

    Clinical benefits were advocated by the authors to justify the main limitations of AM technology: costs, necessity for technical skills and technological availability. Cost-effectiveness was widely debated in literature: the decreased surgical time and employment of self-fabricated 3DP models or guides (instead of outsourced manufacturing) appeared to counter balance the price of the starting technological investments and the technical skills required for pre- and postprocessing printing activity 94. Interestingly, for 34% of studies on customised surgical planning, a specific description of the technology adopted was not available (Fig. 4): this arises from the choice of externalization of the 3D printing process, as often declared by authors themselves 45 77 80 93 110 121. To date, the rapid expansion of AM machines and materials has significantly lowered costs, making this technology more accessible. The most employed technology in this field of application was power bed fusion (27%), which offers medical grade materials (like titanium, or biocompatible polyamide) to be used as intra-operative templates, followed by material extrusion (12%), which also offers biocompatible materials, even if with lower printing resolution. Surgical and preclinical education represents the second most studied 3DP application. Surgical training traditionally made use of physical models, animals, or human cadavers. The adoption of both fixed and fresh human specimens in labs has long been and still is a core component in training for ENT surgery, but it has certain limitations such as transmission of infectious agents, exposure to potentially carcinogenic formaldehyde and excessive costs. More recently, 3DP models were used in the teaching of complex anatomy and to simulate critical surgical procedures with particular regard to temporal bone and skull base dissection. The most employed AM technology for this application (Fig. 4) was material extrusion (39%): this is not surprising, since this is the most affordable technology, especially in terms of printing materials. Material extrusion is actually the most suited to apply for teaching and training, where models are usually subjected to damage and need to be produced in high numbers. 25% of studies used power bed fusion machines, thanks to the availability of materials (e.g. polyamide) with mechanical properties that are suitable for drilling and dissection operations. The complexity of temporal bone anatomy and related surgical procedures, essentially based on bone drilling and removal, explain the extensive research on this issue.

    The evolution of 3DP systems and materials has enabled the reproduction of even the finest chromatic details and mechanical properties of the object resulting in highly representative 3DP simulators. These solutions are unfortunately still expensive, and consequently less employed for the production of didactic devices, as confirmed by the limited use of technologies with high chromatic resolution (binder jetting, 11%) and with tuneable mechanical properties (material jetting, 11%).

    Tissue engineering and implantable prostheses is discussed in fewer reports since it represents the most recent 3DP application, but it also entails more exciting future perspectives. The current literature reported the application of 3DP customised titanium alloy prostheses in 33 cases of mandibular reconstruction after tumour resection. Power bed fusion is confirmed as the most widely employed technology in the field, used in 50% of studies: the most common materials are titanium and cobalt-chrome, which are also widely employed in implant standard manufacturing. Preliminary data have provided encouraging results in terms of safety and effectiveness, opening new frontiers of investigation.

    Nowadays, AM technology has been involved in the production of biocompatible matrices aimed to be cellularised (scaffold), hence forming a new functional tissue. ENT scaffold research is at present confined to a preclinical stage (in vitro and animal testing), with relevant applications in the reconstruction of the upper aerodigestive tract 133 134, replacement of tympanic membrane 135 and plastic rebuilding of auricular and nasal cartilages 136 137. Even though scaffold research is in its infancy, it represents a future direction of high interest. New perspectives will concern the microstructure of 3DP scaffolds to overcome many currently unsolved questions as well as proper vascularisation to avoid cell degeneration and adequate stem cell proliferation/specialisation. The final goal would entail functional aspects to produce functional tissues and organs by involvement of multiple types of cells and biomaterials.

    Moreover, in the foreseeable future, technical advancements will possibly provide a better solution to issues involving biocompatibility and sterilisation protocols of 3DP materials.

    Conclusions

    3DP systems have revolutionised prototyping in the industrial field by lowering production time from days to hours and costs from thousands to only a few dollars. Today, 3D printers are no longer confined to prototyping, but are increasingly employed in the medical discipline with fascinating results, even in many aspects of otorhinolaryngology. Nevertheless, current reports are still limited to small case-series of patients and lack of comparative objective data to validate 3DP technology in daily clinical practice. 3DP bioengineering is at the beginning of an exciting research field, and the positive results to date are far from what it will be possible to achieve in forthcoming clinical applications.

    Figures and tables

    Fig. 1..

    Fig. 2..

    Fig. 3..

    Fig. 4..

    Table I..

    SURGICAL AND PRECLINICAL EDUCATION
    Field of work Authors, year AM category 3D printer 3DP material
    Temporal bone dissection training model Cohen J et al., 2015 12 Material extrusion Dimensions SST 1200es Abs + resin (support material)
    Da Cruz MJ et al., 2015 13 Binder jetting Spectrum Z510 Chalk-like powder + binder + colors
    Hochman JB et al., 2015(1) 14 Binder jetting ZPrinter 650 Chalk-like powder + binder + colors
    Hochman JB et al., 2015(2) 15 Binder jetting ZPrinter 650 Chalk-like powder + binder + colors
    Longfield EA et al., 2015 16 Binder jetting Spectrum Z510 Chalk-like powder + binder + colors
    Mowry SE et al., 2015 17 Material extrusion MakerBot 2x ABS + HIPS
    Rose AS et al., 2015 18 Vat photopolymerisation Objet Connex 350 Photo-polymer resins with different mechanical properties
    Hochman JB et al., 2014 19 Binder jetting ZPrinter 650 Chalk-like powder + binder + colors
    Unger BJ et al., 2014 20 Binder jetting ZPrinter 650 Chalk-like powder + binder + colors
    Mick PT et al., 2013 21 Binder jetting ZPrinter 650 Zp ® 131 powder binder(Zb ® 7) + colors
    Roosli C et al., 2013 22 Binder jetting Spectrum Z510 Chalk-like powder + binder + colors
    Bakhos D et al., 2010 23 Vat photopolymerisation SLA ® 5000 Somos ® 14120
    Mori K, 2009 24 Powder bed fusion NA (commercial available prototype) Polyamide nylon and glass beads
    Mori K et al., 2009 25 Powder bed fusion NA (commercial available prototype) Polyamide nylon and glass beads
    Mori K et al., 2008 26 Powder bed fusion NA (commercial available prototype) Polyamide nylon and glass beads
    Suzuki M et al., 2007 27 Powder bed fusion NA Polyamide nylon and glass beads
    Grunert S et al., 2006 28 Binder jetting Spectrum Z510 Plaster + post-processing with polyurethane and acetone
    Suzuki M et al., 2004(1) 29 Powder bed fusion NA Polyamide nylon and glass beads
    Suzuki M et al., 2004(2) 30 Powder bed fusion NA Polyamide nylon and glass beads
    Begall K et al., 1998 31 Vat photopolymerisation Laser Model stereolithographic System by Fockele & Schwarze GmbH Photosensitive; expoxy resins
    Surgical middle ear training model Monfared A et al., 2012 32 Material jetting Objet Polyjet printer Combination of 2 photosensitive resins
    Endoscopic ear surgery training model Barber SR et al., 2016 33 Binder jetting ZPrinter 650 Zp ® 151 composite material + binder (ColorBond zbond ® 90) + colors
    Functioning anatomical middle ear model Kuru I et al., 2016 34 Powder bed fusion EOS Formiga P100 Polyamide powder PA2200
    CUSTOMISED SURGICAL PLANNING
    Field of work Authors, year AM category 3D printer 3DP material
    Temporal bone surgical simulation Rose AS et al., 2015 35 Material jetting Objet Connex 350 Photo-polymers with different mechanical properties
    Suzuki M et al., 2005 36 Powder bed fusion NA Polyamide nylon and glass beads
    Suzuki M et al., 2004(1) 29 Powder bed fusion NA Polyamide nylon and glass beads
    Lopponen H et al., 1997 37 Vat photopolymerisation NA Acrylic solution
    Andrews JC et al., 1994 38 Vat photopolymerisation 3D Systems SLA 250 Liquid plastic
    Template-guided surgery Pai I et al., 2016 39 Material jetting Objet Eden 250 Transparent photo-polymer
    Matsumoto N et al., 2015 40 Vat photopolymerisation NA Transparent photo-polymer
    Cho B et al., 2014 41 Material jetting Objet Connex 500 Transparent photo-polymer
    Takumi Y et al., 2014 42 Vat photopolymerisation NA Transparent photo-polymer
    Navigation for otoneurosurgery Yamashita M et al., 2016 43 Material jetting Objet Connex 500 Phantom TangoPlus FLX930, VeroWhitePlus RGD835
    Template VeroWhitePlus RGD835
    Ritacco LE et al., 2015 44 NA NA NA
    Oka M et al., 2014 45 NA NA NA
    Cho B et al., 2013 46 Powder bed fusion NA NA
    Matsumoto N et al., 2012 47 Powder bed fusion NA NA
    Matsumoto N et al., 2009 48 Powder bed fusion NA NA
    Lateral skull base approaches Muelleman TJ et al., 2016 49 Material extrusion uPrint SE Plus Thermo-plastic material
    TISSUE ENGINEERING AND IMPLANTABLE PROSTDESIS
    Field of work Autdors, year AM category 3D printer 3DP material
    Prosthesis for superior canal dehiscence Kozin ED et al., 2015 50 Vat photopolymerisation FormLabs Form 1+ Photo-polymer
    Powder bed fusion EOS Formiga Plastic-based material; Aluminium-based material
    Otologic studies classified according to each area of interest.

    Table II..

    SURGICAL AND PRECLINICAL EDUCATION
    Field of work Authors, year AM category 3D printer 3DP material
    Endoscopic sinonasal and skull base training models Chang DR et al., 2017 51 Material extrusion Airwolf 3D HD2X ABS + molding with Aquasil Ultra XLV silicone
    Tai BL et al., 2016 52 Material extrusion NA Thermo-plastic material
    Narayanan V et al., 2015 53 Material jetting Objet Connex 500 Photo-polymers with different mechanical properties
    Chan HHL et al., 2015 54 Paranasal sinus phantom Material extrusion Vantage - Stratasys ABS
    Skull base phantom Binder jetting ZPrinter 310 - ZCorp ZP-130 plaster powder + CA101 cyanoacrylate; ZP-15 plaster powder + infiltrant elastomeric
    Mandible templates Material extrusion Vantage - Stratasys Polycarbonate
    Septoplasty training model AlReefi MA et al., 2017 55 Material jetting Objet Connex 500 VeroWhitePlus, Tango-Plus and their combination to simulate different mechanical properties
    Nosebleed training model Estomba C et al., 2016 56 NA NA PLA + Polyurethane
    Anatomical models Sander IM et al., 2017 57 Material extrusion LulzBot TAZ 5 PLA
    CUSTOMISED SURGICAL PLANNING
    Field of work Authors, year AM category 3D printer 3DP material
    Template-guided surgery Onerci Altunay Z et al., 2016 58 Binder jetting Spectrum Z510 Z131 powder
    Daniel M et al., 2011 59 Binder jetting ZPrinter 310 plus NA
    Endoscopic sinus surgery simulation Raos P et al., 2015 60 Binder jetting ZPrint 310 NA
    TISSUE ENGINEERING AND IMPLANTABLE PROSTHESIS
    Field of work Authors, year AM category 3D printer 3DP material
    Customised prosthesis Nahumi N et al., 2015 61 NA NA PolyEtherEtherKetone
    Rhinologic studies classified according to each area of interest.

    Table III..

    SURGICAL AND PRECLINICAL EDUCATION
    Field of work Authors, year AM category 3D printer 3DP material
    Laryngeal model Kavanagh KR et al., 2017 62 Material extrusion MakerBot ABS, PLA, HIPS
    Johnson CM et al., 2016 63 Material extrusion MakerBot 2XL ABS (best performance), HIPS, PLA; Dragon Skin Fast silicon casting in a 3D printed mold
    Ainsworth TA et al., 2014 64 Material extrusion Dimension Elite - Stratasys ABSplus + silicone casting
    Carotid artery model Govsa F et al., 2017 65 Material extrusion MakerBot PLA
    Tracheostoma model Grolman W et al., 1995 66 Vat photopolimerisation NA Synthetic liquid resin
    CUSTOMISED SURGICAL PLANNING
    Field of work Authors, year AM category 3D printer 3DP material
    Guided surgery for oro-mandibular resection and reconstruction Bosc R et al., 2017 67 Material jetting Material extrusion Objet 30Pro – Stratasys Zortrax M200 - Zortrax SARL Biocompatible photopolymer ABS
    Rachmiel A et al., 2017 68 Skull Material jetting Objet260 Dental - Stratasys Photopolimer resin
    Template Powder bed fusion EOS Titanium
    Shah S et al., 2017 69 Binder jetting ZPrinter 310 plus Gypsum-based material
    Lee UL et al., 2016 70 Powder bed fusion Arcam A1 (Electron Beam Melting) Ti-6Al-4 V-ELI medical grade powder
    Lim SH et al., 2016 71 Mandible Binder jetting ProJet 360-3D Systems NA
    Cutting/position-ing guides Material jetting ProJet 3500 HDMax - 3D Systems Biocompatible materials
    Numajiri T et al., 2016 72 Material extrusion MakerBot PLA
    Yamada H et al., 2016 73 NA NA NA
    Chan HHL et al., 2015 54 Paranasal sinus phantom Material extrusion Vantage - Stratasys ABS
    Skull base phantom Binder jetting ZPrinter 310 - ZCorp ZP-130 plaster powder + CA101 cyanoacrylate; ZP-15 plaster powder + infiltrant elastomeric
    Mandible templates Material extrusion Vantage - Stratasys Polycarbonate
    Man QW et al., 2015 74 NA NA NA
    Modabber A et al., 2015 75 Powder bed fusion NA Polyamide Powder
    Reiser V et al., 2015 76 Material jetting A Objet – Stratasys machine (Model NA) Biocompatible plastic polymers
    Schepers RH et al., 2015 77 NA NA Polyamide (for the cutting guides)
    Shan XF et al., 2015 78 Residual skull Material extrusion Stratasys FDM 400-mc NA
    Mesh NA NA Titanium
    Steinbacher DM et al., 2015 79 NA
    Succo G et al., 2015 80 NA NA NA
    Wilde F et al., 2015 81 Powder bed fusion NA Polyamide
    Ayoub N et al., 2014 82 Powder bed fusion NA NA
    Azuma M et al., 2014 83 Binder jetting ZPrinter 310 plus NA
    de Farias TP et al., 2014 84 Binder jetting Z-Corp Spectrum Z510 Gypsum, cyanoacrylate, and ZP150
    Liu YF et al., 2014 85 Powder bed fusion Sinterstation HiQ +HiSTM - 3D Systems DuraForm - biocompatible nylon
    Modabber A et al., 2014 86 Powder bed fusion NA Polyamide
    Tsai MJ et al., 2014 87 NA NA NA
    Watson J et al., 2014 88 Powder bed fusion Direct metal Powder bed fusion (Model NA) Medical-grade titanium alloy Ti6AL4V - 3TRPD
    Wilde F et al., 2014 89 Powder bed fusion NA Biocompatible Polyamide
    Yamada H et al., 2014 90 NA NA NA
    Coppen C et al., 2013 91 Powder bed fusion NA DuraForm PA - 3DWorknet
    Foley BD et al., 2013 92 NA NA NA
    Hanasono MM et al., 2013 93 NA NA NA
    Mazzoni S et al., 2013 94 Plate Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Titanium Ti64
    Guide Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Cobalt-Chrome MP1
    Mandible NA Stratasys machine Resin
    Zheng GS et al., 2013 95 Vat photopolymerisation SLA-3500 3D Systems NA
    Ciocca L et al., 2012(1) 96 Plate Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Titanium Ti64
    Guide Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Cobalt-Chrome MP1
    Mandible Material extrusion Stratasys machine ABS
    Ciocca L et al., 2012(2) 97 Plate Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Titanium Ti64
    Guide Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Cobalt-Chrome MP1
    Mandible Material extrusion Stratasys machine ABS
    Dérand P et al., 2012 98 Powder bed fusion ARCAM EBM A2 Ti6Al64V ELI powder
    Hou JS et al., 2012 99 NA NA Photopolymer
    Lethaus B et al., 2012 100 Material extrusion Maastricht Instruments NA
    Modabber A et al., 2012(1) 101 Guide Powder bed fusion NA Polyamide
    Skull NA NA Acrylic Resin
    Modabber A et al., 2012(2) 102 Guide Powder bed fusion NA Polyamide
    Skull NA NA NA
    Patel A et al., 2012 103 NA NA NA
    Sink J et al., 2012 104 NA NA NA
    Wilde F et al., 2012 105 Binder jetting ZTM 510-4D Concepts NA
    Zheng GS et al., 2012 106 Vat photopolymerisation SLA-3500 3D Systems NA
    Abou-ElFetouh A et al., 2011 107 Vat photopolymerisation Binder jetting 3D Systems InVision Si2 3D Systems VisiJet SR 200 NA NA
    Antony AK et al., 2011 108 NA NA NA
    Bell RB et al., 2011 109 NA NA Acrylic resin
    Hou JS et al., 2011 110 NA NA Polybutadiene-styrene resin
    Mehra Pet al., 2011 111 Vat photopolymerisation Material extrusion NA Acrylic, Epoxy Starch
    Yamanaka Y et al., 2010 112 NA NA Acrylic plastic
    Zhou LB et al., 2010 113 Vat photopolymerisation LPS 600 laser prototyping Resin
    Cohen A et al., 2009 114 Material jetting Eden 500 V Photo-polymer
    Farina R et al., 2009 115 Vat photopolymerisation Binder jetting 3D Systems SLA-250/30 Z-Corporation Z406 8110 resin (DSM Somos) Starch-cellulose material
    Juergens P et al., 2009 116 NA NA NA
    Leiggener C et al., 2009 117 Powder bed fusion NA Medical grade polyamide
    Liu XJ et al., 2009 118 NA NA Resin
    Chow LK et al., 2007 119 NA NA Starch, epoxy resin, acrylic
    Lee JW et al., 2007 120 NA NA NA
    Ro EY et al., 2007 121 NA NA Epoxy
    Toro C et al., 2007 122 Vat photopolymerisation SLA 3500 – 3D Systems Epoxy resin Watershed 11120
    Yeung RWK et al,. 2007 123 NA NA NA
    Hallermann W et al., 2006 124 Powder bed fusion NA Duraform PA12-3D Systems
    Hannen EJM et al., 2006 125 NA NA Resin
    Cunningham LL et al., 2005 126 Vat photopolymerisation Binder jetting 3D Systems SLA-250/30 Z-Corporation Z406 8110 resin (DSM Somos) Starch-cellulose material
    Wong TY et al., 2005 127 NA NA NA
    Singare S et al., 2004 128 Vat photopolymerisation LPS 600 Photo-polymer
    Kernan BT et al., 2000 129 NA NA NA
    Komori T et al., 1994 130 Vat photopolymerisation Solid Creation System (D-MEC Ltd, Tokyo, Japan), Desolight SCR- 100, D-MEC Ltd)
    Guided surgery for cranio-cervicofacial teratoma Wiedermann JP et al., 2017 131 NA NA NA
    Carotid artery model Govsa F et al., 2017 65 Material extrusion MakerBot PLA
    MRI compatible laryngoscope Paydarfar JA et al., 2016 132 Material jetting Objet Eden250 - Stratasys MED610 (Stratasys) biocompatible photopolymer
    TISSUE ENGINEERING AND IMPLANTABLE PROSTHESIS
    Field of work Authors, year AM category 3D printer 3DP material
    Customised prosthesis for mandibular reconstruction Rachmiel A et al., 2017 68 Skull Material jetting Objet260 Dental - Stratasys Photopolymer resin
    Template Powder bed fusion EOS Titanium
    Lee UL et al., 2016 70 Powder bed fusion Arcam A1 (Electron Beam Melting) Ti-6Al-4 V-ELI medical grade powder
    Schepers RH et al., 2015 77 NA NA Polyamide (for the cutting guides)
    Shan XF et al., 2015 78 Residual Skull Material extrusion Stratasys FDM 400-mc NA
    Mesh NA NA Titanium
    Watson J et al., 2014 88 Powder bed fusion Direct metal Powder bed fusion (Model NA) Medical-grade titanium alloy Ti6AL4V - 3TRPD
    Mazzoni S et al., 2013 94 Plate Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Titanium Ti64
    Guide Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Cobalt-Chrome MP1
    Mandible NA Stratasys machine Resin
    Ciocca L et al., 2012(1) 96 Plate Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Titanium Ti64
    Guide Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Cobalt-Chrome MP1
    Mandible Material Extrusion Stratasys machine ABS
    Ciocca L et al., 2012(2) 97 Plate Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Titanium Ti64
    Guide Powder bed fusion EOSINT M270 - Electro-Optical Systems EOS Cobalt-Chrome MP1
    Mandible Material extrusion Stratasys machine ABS
    Dérand P et al., 2012 98 Powder bed fusion ARCAM EBM A2 Ti6Al64V ELI powder
    Zhou LB et al., 2010 113 Vat photopolymerisation LPS 600 laser prototyping Resin
    Singare S et al., 2004 128 Vat photopolymerisation LPS 600 Photopolymer
    Head and neck studies classified according to each area of interest.