PROBLEMsolving
Narval CC & D-SAD Strap Failures: Where would you place the Fuse? by John Viviano, DDS, DABDSM
A
lthough 3D printed nylon appliances such as the Narval CC by ResMed and D-Sad by Panthera have demonstrated themselves to be extremely robust, it turns out that they do have an “Achilles Heel”: the advancement strap. Even though this only applies to those patients that adequately challenge their appliance through extreme bruxism, it would be prudent to have a plan in place to manage this issue.
Figure 1: Narval CC
Figure 2: D-SAD
46 DSP | Spring 2016
Let’s start by understanding the “raison d’etre”. The easiest way to explain this is by comparing the advancement strap to an electrical fuse. Patented in 1880 by Thomas Edison, a fuse guards against catastrophic surges of electricity. By placing a ‘Fuse” between the electrical source and the electronic circuitry, the integrity of the circuitry is preserved in the event of an electrical surge, protecting from catastrophic events such as damage to Hard Drives, Mother Boards, Circuit Boards etc. In the oral cavity, “extreme bruxism events” can be likened to these “electrical surges”. According to the Oxford Handbook of Applied Dental Sciences (2002), maximum biting forces generate around 110 to
160 lbs/sf. Typically, for bruxers that sufficiently challenge their appliances, catastrophic events such as appliance breakage is common. In 3D printed nylon appliances, the advancement straps actually act as a “Fuse”. When these straps stretch or fail, they protect from more serious “Catastrophic” events such as breakage of the appliance body, restorative work or teeth, and straining of the periodontium, musculature or Temporomandibular Joint. When the D-SAD first arrived, it came with a much beefier strap than the Narval CC. Which at first appeared to be an enhancement, until they demonstrated to be problematic with heavy bruxers; the attachment nubs (Figure 3) simply distorted,