In vitro comparison of the flexibility of different splint systems used in dental traumatology

The aim of the study was to evaluate the flexibility of five different splint systems [polyethylene fibre-reinforced splint (Ribbond THM, Ribbond Inc., Seattle, WA, USA), resin splint (RS), wire-composite splint (WCS), button-bracket splint (BS) and titanium trauma splint (TTS)] commonly used in clinical practice for the treatment of dental traumatic injuries involving the periodontal supporting tissues.

For the experimental study, a resin cast of the upper arch was manufactured, where teeth 11, 12 and 21 (used for the stress analysis) were inserted in a non-rigid fashion so as to allow for replacement, whereas the other teeth were permanently fixed to the corresponding sockets. Two different test sessions were performed for each splint: (i) stress analysis with increasing intensity ranging between 0 and 50 N directed along the tooth's longitudinal axis; (ii) stress analysis with 45 degrees of oblique force of increasing intensity ranging between 0 and 30 N. For each loading direction, five recordings were conducted without a splint, followed by five with the splint applied. The energy required to modify the position of the teeth was calculated for both the splinted and un-splinted teeth and the difference between the two values was determined. Energy variation was assessed for the testing of both axial (DeltaE(a)) and oblique force (DeltaE(o)). DeltaE represents the rigidity index of the analysed contention devices: high DeltaE values correspond to high rigidity materials.

The RS showed the highest DeltaE value for the axial stress analysis, whereas the highest DeltaE value at a 45 degrees was recorded for the WCS and RS. For both tests, the lowest DeltaE values were recorded for the TTS and Ribbond THM splints.

The data show that the contention devices with the highest flexibility are the TTS and the Ribbond THM as they exhibit a lower energy variation needed for splint deformation compared with the other materials that were examined.