In vitro Evaluation of Static Frictional Forces at the Bracket-archwire Interface

Abstract

The aim of this research is to compare the static frictional forces generated by different bracket-archwire couples. The study group consisted of three types of ceramic brackets (polycrystalline alumina with stainless steel slot, polycrystalline alumina and monocrystalline alumina), one stainless steel bracket and two types of archwires (0.016` NiTi and 0.019x0.025` SS). Brackets corresponding to the upper right quadrant (form upper right central incisor to the upper right second premolar) were bonded on standardized maxillary models and elastomeric ligatures were used to secure the archwire to the bracket system. An in-vitro experiment was conducted using a testing machine designed to measure the compression and traction force, both in dry and wet testing conditions. The results indicated statistically significant differences between most bracket-archwire groups. According to the data obtained, stainless steel brackets produced the lowest static frictional forces, regardless of test conditions and orthodontic archwire type. Polycrystalline ceramic brackets with stainless steel slot generated higher static frictional forces than stainless steel brackets, but lower than ceramic brackets when combined with the 0.019`�0.025` SS archwire. No significant differences were found between polycrystalline and monocrystalline ceramic brackets. Experiments performed with 0.019�0.025` SS archwire produced greater static frictional forces than those with 0.016` NiTi wire. Static frictional forces were not significantly influenced by the test conditions.