Stiffness characteristics of splints for fixation of traumatized teeth

Traumatic dental injuries (TDI) are treated by repositioning and splinting. Ideally, injured teeth should possess some mobility for optimal periodontal and pulp healing. Splints should be easy to apply in emergencies, affordable, and esthetically acceptable. The aims were to compare some clinically used splints with regard to stiffness (measured in Nm(-1)), esthetics, cost, and ease of application.

Six splints were applied to dental models using an acid-etched bonding technique. One central incisor was adjusted to give 1 mm of horizontal movement at the incisal edge. The mobilized tooth was then connected to adjacent teeth with either twistflex wire (TF), titanium trauma splint (TTS), single (SFG) and double fiberglass (DFG), nylon (fishing) line (FL), or power chain (PC). A horizontal force was then gradually applied to the incisor in a standardized manner with a spherical probe (1.65 mm radius), monitoring force with a 50N load cell and displacement with a linear variable differential transformer (LVDT). Signals were amplified, converted digitally (14-bit analog-to-digital converter), and displayed in real time to show the splint stiffness. Splints were also ranked with regard to esthetics, application time needed, and ease of application cost.

FL and PC were the least stiff, averaging 5.7 and 6.3 Nm(-1), respectively. TTS averaged 6.9 Nm(-1), while SFG and TF averaged 18.5 and 18.4 Nm(-1), respectively. DFG was the stiffest, averaging 24.3 Nm(-1). PC and SFG were the fastest to apply. FL showed the best esthetic score, followed by TTS and PC. TTS was the most expensive splint, while FL, PC, SFG, DFG, and TF showed similar costs.

Of these TDI splints, DFG should be avoided for flexible splinting because it is too stiff. PC may be an interesting novel alternative, affording sufficient mobility due to its low stiffness.