Fuerza de descarga entre brackets de autoligado de diferentes prescripciones, con alambres niquel titanio de diferentes calibres

During dental movement, sliding occurs between the archwire and the bracket causing friction, which modificates the force applied to the teeth. Friction along with other factors such as binding and notching constitute frictional resistance that increases the force with which the archwire is activated and reduces the discharge force. To reduce required archwire adjustments, bracket manufacturers incorporated special slot designs to achieve proper tooth positioning in all three planes of space; These additions were called prescriptions, which have been varied and have become routine in clinical practice. Since these prescriptions can affect frictional resistance components, their impact must be studied. Objective: Determine the differences in the discharge force between passive self-ligating brackets of two different prescriptions, combined with Nickel Titanium archwires of four different calibers. Method: Quasi-experimental in vitro intervention study. The observation unit was the archwire-bracket system. Two metal self-ligating prescriptions (Roth, MBT), 0.022 ”slot and superelastic Nickel Titanium archwires of 4 different calibers were included. Loading and unloading values were recorded in second order movements at different heights. The object of study was related to frictional resistance, measured through the discharge force. Results: 21% of the studied distances displayed statistically significant differences (p≤0.05) between the MBT and Roth prescriptions in Laser Blue SL Passive® brackets in occlusogingival movements and 13% for gingivocclusal movements. 71% of these showed higher values in Roth prescription. For Empower® brackets, statistically significant differences (p≤0.05) were found in 42% of the analyzed distances between MBT and Roth in occlusogingival and gingivocclusal movements, 65% of these were greater for the Roth prescription. Conclusions: In the highest percentage of cases, no significant differences were found when comparing the Roth and MBT prescriptions, as well as in the different second-order movements, archwire caliber and stiffness.