Improved anchoring nails: design and analysis of resistance ability : Tensile test and finite element analysis (FEA) of improved anchoring nails used in temporomandibular joint (TMJ) disc anchor.

BACKGROUND: Anchorage is one of the most important treatments for severe temporomandibular joint disorder (TMD). Anchoring nails have shown great success in clinical trials; however, they can break under pressure and are difficult to remove. In this study, we aimed to evaluate an improved anchoring nail and its mechanical stability. METHODS: The experiment consisted of two parts: a tensile test and finite element analysis (FEA). First, traditional and improved anchoring nails were implanted into the condylar cortical bone and their tensile strength was measured using a tension meter. Second, a three-dimensional finite element model of the condyles with implants was established and FEA was performed with forces from three different directions. RESULTS: The FEA results showed that the total force of the traditional and improved anchoring nails is 48.2 N and 200 N, respectively. The mean (±s.d.) maximum tensile strength of the traditional anchoring nail with a 3-0 suture was 27.53 ± 5.47 N. For the improved anchoring nail with a 3-0 suture it was 25.89 ± 2.64 N and with a 2-0 suture it was above 50 N. The tensile strengths of the traditional and improved anchoring nails with a 3-0 suture was significantly different (P = 0.033-< 0.05). Furthermore, the difference between the traditional anchoring nail with a 3-0 suture and the improved anchoring nail with a 2-0 suture was also significantly different (P = 0.000-< 0.01). CONCLUSION: The improved anchoring nail, especially when combined with a 2-0 suture, showed better resistance ability compared with the traditional anchoring nail.

A resistive Q-switch for low-field NMR systems.

An NMR Q-switch was designed and constructed specifically for use with low-field NMR apparatus. This featured a comparatively simple resistive damping design. It served to reduce the r.f. probe ring-down time, and hence reduced the signal acquisition delay from 25 ms to 9 ms, on an Earth's magnetic field NMR system. The advantage of this earlier acquisition was demonstrated for both an aqueous suspension of iron oxide particles and using an NMR flow meter.