Can Fracture Reduction be Attempted Through a 3D-Printed Guide Template Without Maxillomandibular Fixation?

Background: Computer-aided design and manufacturing (CAD/CAM) is widely used in clinical practice. This technology may change existing methods for mandibular fracture management.

Purpose: The purpose of this in-vitro study was to determine if the reduction for mandibular symphysis fracture can be performed without maxillomandibular fixation (MMF) using 3-dimensional (3D)-printed template.

Study Design, Setting, And Sample: This in-vitro study was designed as a proof-of-concept. The sample was composed of 20 existing pairs of intraoral scan and computed tomography (CT) data. A mandibular model stereolithography (STL) file was created by merging the STL file obtained for the bimaxillary dentitions with the CT DICOM file, and this was set as the original model. Using the original model, a STL file of a fracture model of the mandibular symphysis was created using CAD. A template similar to a wafer or an implant guide was manufactured to restore original occlusion, and the mandibular fracture model was reduced and fixed using the 3D-printed template and wire. This was set as the experimental group. The 3D coordinate system error was measured at 6 landmarks and statistically compared using scan data between models of the groups.

Predictor/exposure/independent Variables: Reduction techniques with MMF or without MMF using guide template for mandibular fracture model.

Main Outcome Variable(s): The 3D coordinate system error (mm).

Covariates: The position of landmarks.

Analyses: The Mann-Whitney U test, student's t-test, and the Kruskal-Wallis test were used to analyze the coordinate errors between the landmarks. A P value of < .05 was considered statistically significant.

Results: The 3D error value of the control and experimental group were 1.06 ± 0.63 mm (range: 0.11 to 2.92 mm) and 0.96 ± 0.48 mm (range: 0.2 to 2.95 mm), respectively. There was no statistical difference between the control and experimental group. There was a statistically significant difference in the lower 2 and lower 3 landmarks compared to the upper 1 (P = .001 and .000, respectively) before and after the reduction in the experimental group.

Conclusion And Relevance: This study demonstrates that the reduction using a 3D-printed guide template for the mandibular symphysis fracture could be possible even without the MMF.