Mechanical compression testing for three-dimensionally printed orthodontic springs with different coil numbers: in vitro study.

Abstract

Objective: Purpose of this study was to evaluate the influence of different design parameters regarding the number of coils for orthodontic 3D printed springs using the computer aided design/ computer aided manufacturing (CAD/CAM) technology.Materials and Methods: Test specimens using 3D printable experimental flexible material (Code: BM2008, GC, Tokyo, Japan) were printed using 3D printer MAX (Asiga, Sydney, Australia).The specimens were divided into five groups according to their coil numbers, including a control group C with four coils (n=10), group A with two coils (n=10), group B with three coils (n=10), group D with five coils (n=10) and group E with six coils (n=10).All specimens were mechanically tested using Zwick Z010 machine (Ulm, Germany) and digitally designed using Autodesk Netfabb CAD software (San Rafael, CA, USA).Statistical analysis was performed using t-test to compare the values of the groups (p<0.001).Results: The highest value in all groups was achieved by 6.23N/mm in group B while the lowest value was achieved by 0.87N/mm in group E.Moreover, significant results can only be detected between groups A and B when compared to master group C (p<0.001).Step-wise compression testing with 0,1mm steps, each with 5 minutes holding time, was conducted with 10 steps for each group with the exception of group A, which was tested with 5 steps.Conclusion: 3D printed springs are mechanically affected by the number of coils.The smaller the coil numbers, the higher is the significance level (p<0.001).