Utility of Creating Surgical Guide Using Sterilizable and Inexpensive Dental Impression Silicon in Free Fibula Flap Mandibular and Maxillary Bone Reconstruction

Introduction

In recent years, mandibular and maxillary bone reconstructive surgery using free fibula flap transfer is a commonly-performed surgical procedure, and increasing number of reports have been published about preoperative simulation surgery using models that utilize 3D printers¹⁾. However, 3D printed models made from sterilizable materials are uncommon, making it difficult to introduce the model into the surgical field. One problem is that the use of such materials would significantly increase the cost of surgery. We introduce a method in which we perform osteotomy on the 3D fibula model preoperatively by using a guide molded from the inexpensive and easy-to-use silicon Protesil labor® to the correct bone size and osteotomy angle. This formed silicone mold was steam autoclave sterilized and used within the surgical field as an osteotomy guide. This reduced the time required for osteotomy and was effective in accurate reproduction of the simulation surgery on the surgical field.

Materials and Methods

Six patients who were treated between October 2016 and February 2017 were included in this study. One patient underwent maxillary segmental resection for maxillary cancer, one patient underwent surgical resection and left hemimandibulectomy for mandibular gingival cancer and the remaining four patients underwent segmental mandibulectomy for mandibular gingival cancer. Free fibula flap transfer was carried out for reconstruction in all patients. Preoperative CT images and a 3D printer were used to create simulation models for the mandible, maxilla and fibula. Preoperative simulation surgery was performed by cutting away the scheduled region of the mandibular and maxillary bone models, after which the fibula model was cut at an angle that allowed it to be inserted into the defect region. The 3D models used materials that were not sterilizable. Protesil labor®, a dental silicon, was placed on the cut fibula models and given approximately 5 minutes to harden. It was then cut to the same size with the fibula bone model, and sterilized in an autoclave. After these processes, it was used as a surgical guide to mark the bone cutting line on the fibula flap.

Results

We checked the differences between pre- and post-operative bone angles and bone lengths for all cases using simulation surgery models and post operative 3DCT. Mean bone angle difference was 2.7 degree and the mean bone length difference was 1.9mm. The mean bone cutting time was 35 minutes. The cost of producing the surgical guide was approximately 5 US dollars/piece.

 

Conclusion

Creating a surgical guide using sterilizable material allows the surgeon to perform the osteotomy more accurately and in less time. It is also inexpensive and does not require the use of specialized instruments such as expensive computer softwares and sterilizable 3D printer materials. We believe that the use of this surgical guide is simple, and applicable even in smaller hospitals.

References

1)Matthew M. Hanasono, Skoracki RJ. Computer-Assisted Design and Rapid Prototype Modeling in Microvascular Mandible Reconstruction.Laryngoscope.2013;123:597–604.