Comparative study of classic friction among different archwire ligation systems

Abstract

OBJECTIVE: To describe and compare three alternative methods for controlling classical friction: Self-ligating brackets (SLB), special brackets (SB) and special elastomeric ligatures (SEB). METHODS: The study compared Damon MX, Smart Clip, In-Ovation and Easy Clip self-ligating bracket systems, the special Synergy brackets and Morelli's twin bracket with special 8-shaped elastomeric ligatures. New and used Morelli brackets with new and used elastomeric ligatures were used as control. All brackets had 0.022 x 0.028-in slots. 0.014-in nickel-titanium and stainless steel 0.019 x 0.025-in wires were tied to first premolar steel brackets using each archwire ligation method and pulled by an Instron machine at a speed of 0.5 mm/minute. Prior to the mechanical tests the absence of binding in the device was ruled out. Statistical analysis consisted of the Kruskal-Wallis test and multiple non-parametric analyses at a 1% significance level. RESULTS: When a 0.014-in archwire was employed, all ligation methods exhibited classical friction forces close to zero, except Morelli brackets with new and old elastomeric ligatures, which displayed 64 and 44 centiNewtons, respectively. When a 0.019 x 0.025-in archwire was employed, all ligation methods exhibited values close to zero, except the In-Ovation brackets, which yielded 45 cN, and the Morelli brackets with new and old elastomeric ligatures, which displayed 82 and 49 centiNewtons, respectively. CONCLUSIONS: Damon MX, Easy Clip, Smart Clip, Synergy bracket systems and 8-shaped ligatures proved to be equally effective alternatives for controlling classical friction using 0.014-in nickel-titanium archwires and 0.019 x 0.025-in steel archwires, while the In-Ovation was efficient with 0.014-in archwires but with 0.019 x 0.025-in archwires it exhibited friction that was similar to conventional brackets with used elastomeric ligatures

Understanding the basis of space closure in Orthodontics for a more efficient orthodontic treatment

“… 26 As binding delays tooth movement in the active unit, the reactive unit starts to move, causing anchorage loss. 27 , 28 Accurate control of anterior teeth during space closure in sliding mechanics is essential to the success of orthodontic treatment. When the line of action of force passes below the center of resistance of anterior teeth, a backward moment acts on anterior teeth, resulting in tipping and extrusion of incisors ( Fig 6 ).…”

“… 7 , 27 Simple loops are associated with small activations and rapid force decay, including intermittent force delivery; thus, having a negative impact on treatment efficiency. 28 , 31 Also, as shown by Burstone and Koenig, 6 an error as small as 0.3 mm in the horizontal length of the common vertical loop produces large changes on the M/F ratio, making difference enough to change from root movement to tipping. Due to its characteristics, T-loop has a high M/F ratio and delivers more constant forces over a large deactivation span than vertical loops.…”

Orthodontic Correction of an Anterior Open Bite with Periodontally Compromised Upper Incisors Using Miniscrews

“…Therefore, it was more appropriate to select and apply mechanics that would minimize the force duration and magnitude on the maxillary incisors [11]. Throughout treatment, using Synergy low-friction brackets with six tie wings, only round 0.012 ′′ and 0.014 ′′ NiTi and 0.016 ′′ SS archwires were placed segmentally on the maxillary anterior teeth [12,13]. Also, application of anterior vertical elastics was minimized in regard to force and duration.…”