Improved anchoring nails: Design and analysis of resistance ability

Abstract

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 48.2N and 200N, respectively. The mean (±s.d.) maximum tensile strength of the traditional anchoring nail with a 3-0 suture was 27.53±5.47N. For the improved anchoring nail with a 3-0 suture it was 25.89±2.64N and with a 2-0 suture it was above 50N. 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.