Introduction:
Three-dimensional (3D) printing has been applied in numerous fields of medicine such as orthopedic surgery, maxillofacial surgery, cranial surgery, spinal surgery, and even tissue engineering to improve surgical outcomes. However, few studies have analyzed the time of manufacturing and cost of material consumption and malfunction repair. Moreover, the selection of an appropriate 3D printer and materials is essential. As a result, this retrospective study analyzed 3D printing application in a single institution in terms of usage, time, material consumption, and cost of manufacturing. The selection of 3D printer and materials and trends in 3D-printing manufacturing were also evaluated.

Materials and Methods:
All the information and records on the usage condition of 3D printing machines in Taoyuan Chang Gung Craniofacial Center from December 2014 to January 2021 were collected. The purpose of manufacturing was divided into maxillofacial surgery stents/splints, ear models, and others. We also collected data including machine type and cost, material amount and cost, manufacturing time, number of models, type of surgeons, and malfunction issues. The application of models, manufacturing time, material consumption, and manufacturing cost were considered primary outcomes.

Result :
From December 2014 to January 4, 2021, 5168 models were manufactured. An increase in 3D-printed model production in the last 6 years was noted. Almost 70% of production was for intraoperative maxillofacial stents/splints (n = 3611, 69.9%), followed by ear models (24.1%). The average production of intraoperative maxillofacial stents/splints was 601.8 pieces per year, that for ear models was 208 pieces per year, and that for others was 51.5 pieces per year. The average cost of intraoperative maxillofacial stents/splints and ear models was US$16.7 and US$24.6, respectively, and the average printing time was 2 h and 41 min per object. Orthodontists were involved in 63% of the models. The most frequent major malfunction was damage to the ultraviolet light, and the main minor malfunction was hardware adjustment and associated problems.

Conclusion :
Our data indicated an increasing trend in 3D printing at our craniofacial center over the past 6 years. 3D-printed models are useful in different aspects of clinical practice, such as preoperative simulation, intraoperative guidance, preoperative explanation, and postoperative patient education. Various 3D printer parameters, such as frequency of malfunction and printing layer accuracy, should be considered before use. Material selection was also critical, and we selected transparent biocompatible modeling material to create our intraoperative maxillofacial stents/splints and ear models.