Mechanical evaluation for three-dimensional printed orthodontic springs with different heights-in vitro study

Abstract

Background The orthodontic spring materials in use have a significant influence on the applied forces. The prerequisite to identify the in vitro < force deflection of the CAD/CAM fabricated springs is considered mandatory to identify the material characteristics. The purpose of the present investigation was to evaluate the mechanical load on 3D printed springs using different coil heights. Material and Methods The springs were digitally designed with different coil heights using Autodesk Netfabb CAD software (San Rafael, CA, USA). Test specimens were manufactured using 3D printable experimental flexible material (Code: BM2008, GC, Tokyo, Japan). The specimens were divided according to the coil height into five groups, group A (n=4mm), group B (n=6mm), group C (n=8mm), group D (n=10mm) and group E (n=12mm). All group specimens were mechanically tested using a universal testing machine. Statistical analysis was performed using K-S-Test to compare the values of each to the control group ( p < 0.001). Results The highest value in all groups was achieved by 5.43 N/mm in group A, while the lowest value was achieved by 0.11 N/mm in group E. Conclusions 3D printed springs are mechanically affected by the coil heights and there is a direct correlation to the resulting force. Furthermore, the variations within the investigated groups must be thoroughly investigated prior to clinical application. Key words: CAD/CAM, 3D printing, Orthodontics, mechanical testing, material evaluation.

Clinically Relevant Properties of 3D Printable Materials for Intraoral Use in Orthodontics: A Critical Review of the Literature

“…The amount of torque measured in vitro was more affected by coil diameter than by coil length. The same experimental material was used by Strobele et al [ 48 ] to investigate the effect of coil spring height (4, 6, 8, 10, 12 mm) on compression resistance, and the greatest values were demonstrated by the shortest springs.…”

The three-dimensional displacement tendency of teeth depending on incisor torque compensation with clear aligners of different thicknesses in cases of extraction: a finite element study

“…This was confirmed by Wu et al who pointed out that the cell pressure caused by the optimal orthodontic loading in PDL should not be higher than the capillary pressure in tissue [ 39 ]. Generally, cell pressure and capillary pressure requires principal stress instead of Von-mises stress [ 40 – 42 ]. Based on these factors, the present study calculated and compared the maximal principal stress of the PDL to analyze RP of the incisors.…”