Dimensional Slot Integrity And Precision of Self-Ligating Buccal Tubes

Objectives: The primary advantage of using self-ligating systems have been based on the claim that they provide reduced friction and therefore reduced sliding resistance of the arch wire contained within their respective slots. This form of reduced friction and sliding resistance has been proposed to require less force and therefore produce more physiologic tooth movements. Limited scientific evidence is currently available to establish quality control of these products. Using Micro Computed Tomography (MicroCT), we are analyzing self-ligating molar tubes that are manufactured by different companies as well as provide a novel method for measuring the accuracy and quality of these materials.
Methods: Lower left first mandibular molar samples were obtained from four different manufacturing companies. These samples were scanned using MicroCT, from which each tubes’ internal slot lumens were analyzed for accuracy using precision volumetric measurements. In addition, each lumen was investigated for the presence of any defects or imperfections.
Results: The volumetric slot measurements of all samples investigated were statistically significant (P<0.001) and oversized compared to what is claimed by their respective companies. All samples illustrated varying defects contained within their respective internal slot lumens. Notable defects included notched, beveled and irregular corners, as well as the presence of some bulbous metal projections.
Conclusions: All the companies investigated produced oversized self-ligating buccal tubes as well as samples with various internal slot defects. The potential clinical significance of these dimensional inaccuracies may include an increased amount of friction as well as a lack of torque control during tooth movement.