A Novel Double Arrowhead Auxetic Dental Splint for Avulsed Tooth Reimplantation

A dental splint is a stabilization device designed to support an injured tooth by allowing physiological tooth mobility and redistributing stresses to adjacent healthy teeth. Dental splints incorporating auxetic structures with a negative Poisson's ratio can offer improved biomechanical performance. The aim of the present work is to optimize dimensions and evaluate the biomechanical performance of a superelastic NiTi alloy-based double U-arrowhead (DUA) auxetic dental splint for reducing the stress and tooth mobility of an avulsed tooth.

The DUA splint was optimized by varying dimensions of arm-width (0.5, 0.6, 0.7, 0.8 mm) that influence overall dimensions of motif. Finite element analysis under tensile and bending conditions was conducted to evaluate the effect of arm-width on Poisson's ratio, effective modulus, and effective bending stiffness. The biomechanical performance of the DUA splint was assessed using a 3D maxillary avulsed tooth model under masticatory loading (100 N) applied to the lingual surface of the crown.

On increasing arm-width leads to a gradual increase in effective modulus (36.7-43.6 GPa), bending stiffness (3.1-5.44 N/mm), and reduction in negative Poisson's ratio (-0.21 to -0.01). The avulsed tooth model shows a reasonable reduction in maximum principal stress (11.14%), minimum principal stress (23.89%), and tooth mobility (24.77%) of avulsed tooth and PDL von-Mises stress (26.47%) when splinted with DUA splint of 0.7 mm arm-width. Further comparison with a commercial Titanium trauma splint showed better performance of DUA splint (0.7 mm).

The proposed superelastic NiTi alloy-based DUA auxetic splint with 0.7-mm arm-width reduces tooth mobility and stresses without exceeding biological limits. This will facilitate the reimplantation of the avulsed tooth, ensuring healing of the PDL and allowing physiological tooth mobility for ossification of the alveolar bone around the tooth socket. This will inhibit further complication of the affected tooth such as hyalinization of PDL, root resorption, or tooth ankylosis.