A Structural Analysis of 3D Printed Pediatric Space Maintainers.

Purpose: To design, fabricate, and evaluate in vitro 3D printed space maintainers (SMs) and compare their retentive capabilities to tradi- tional stainless-steel (SS) space maintainers. Methods: E-Guard was selected as the printing material based on flexural strength and elastic modulus. SMs with a claw design were printed, cemented to testing blocks, and vertically loaded to determine failure strength and flexure (n equals 10). The intaglio surfaces of SM bands, printed with plain, crosshatched, or horizontal ridges, were cemented to extracted primary teeth. The force needed to dislodge the bands was compared to cemented traditional SS bands (n equals 14). Results: Flexural strength (mean±standard deviation [SD]) of E-Guide, E-Dent, and E-Guard materials was 65±12, 90±13, 134±25 MPa, respectively. Elastic modulus (mean±SD) was 1.54±0.40, 2.49±0.14, 2.65±0.89 GPa, respectively. When subjected to vertical loading, the mean failure load of 3D printed SMs (E-Guard) was 124 N and the mean deflection at fracture was 1.73 mm. Retention strengths (mean±SD) of 3D printed bands were 32±13, 43±13, 43±16 N for the plain printed, cross- hatched, and horizontal ridges designs, respectively. The retention strength of traditional SS bands was 126±27 N. Conclusions: E-Guard had superior mechanical properties among tested printing resins. Strength and deflection under the vertical load of claw-design 3D printed space maintainers may be adequate as a viable alternative to traditional SMs. Retention of 3D printed SMs was significantly lower than for traditional SS bands. Textured intaglio surfaces did not significantly improve the retention of 3D printed bands.