In Vitro Comparative Evaluation of Frictional Resistance of Connecticut New Arch Wires, Stainless Steel and Titanium Molybdenum Alloy Archwires Against Different Brackets

Abstract

Background and objectives Friction between the bracket and archwire during sliding mechanics is of great concern in orthodontics, as it reduces the effectiveness of the orthodontic appliance and slows down tooth movement. The aim of this study was to evaluate frictional resistance of stainless steel (SS), titanium molybdenum alloy (TMA), and Connecticut new arch (CNA) wires against SS and ceramic brackets. The surface textures of the brackets and wires were also evaluated by scanning electron microscopy (SEM) before and after testing. Method A total of 180 premolar brackets of SS (ORMCO Corp., Orange, CA) and 180 ceramic (3M Unitek, Maplewood, MN) with a 0.022-inch slot and 180 SS, TMA, and CNA wires of 0.017 x 0.025 inches and 0.019 x 0.025 inches were tested. The SS brackets and ceramic brackets were bonded onto the SS bar with cyanoacrylate adhesive with the help of a jig. The wire assembly was vertically mounted and clamped to the jaws of the universal testing machine with 10 N load cell, and friction was measured along with other readings. The surface roughness of brackets and wires were examined using SEM in 200 X magnification before and after testing. Results TMA wire showed the greatest frictional force compared to SS and CNA wire. The frictional force was greater in the 0.019 x 0.025-inch wire compared to the 0.017 x 0.025-inch wires. The highest frictional force was noted in the SS bracket and 0.019 x 0.02-inch TMA wire combination. A statistically significant difference was not seen between the SS bracket and 0.019 x 0.025-inch SS wire and the 0.019 x 0.025-inch CNA wire combinations. SEM showed that the TMA archwire had the roughest surface area compared to SS and CNA wires, and the ceramic bracket had more surface roughness than the SS bracket. Conclusion CNA wire demonstrated frictional resistance similar to the SS wire. CNA wire can be used instead of TMA wire because of its better range of action, high spring back, and less frictional resistance for space closure in sliding mechanics.

Keywords: cna wire; friction; surface roughness.

Figure 1. Mean static friction of bracket and wire combinations

Figure 2. Photomicrography of SS bracket before (A) and after (B) friction testing

SS, stainless steel

Figure 3. Photomicrography of ceramic bracket before (A) and after (B) friction testing

Figure 4. Photomicrography of SS wire had a smooth surface with regular striations before testing

SS, stainless steel

Figure 5. Photomicrography of SS wires showed deep striations after testing

SS, stainless steel

Figure 6. Photomicrography of TMA wires before testing

TMA, titanium molybdenum archwire

Figure 7. Photomicrography of TMA wire showed increased and widened striations after testing

TMA, titanium molybdenum

Figure 8. Photomicrography of CNA wire showed irregular surface with vertical fissures before testing

CNA, Connecticut new arch

Figure 9. photomicrography of CNA wire showed deepening of the fissures after testing

CNA, Connecticut new arch