Lubricating conditions: effects on friction between orthodontic brackets and archwires with different cross-sections

Abstract

Objective: This study investigated the effect of the condition of lubrication on the friction between brackets and NiTi archwires of different rounded cross-sections. Methods: Brackets (Roth, GAC) were affixed to a device connected to a universal testing machine into which segments of archwire were placed (NiTi, Nitinol, GAC) with cross-sections of 0.012-in, 0.016-in and 0.020-in. Once the wire was in the bracket slot, the following lubricants were applied: human saliva (HS: positive control), distilled water (DI), mucin-based (MUC) or carboxymethylcellulose-based (CMC) artificial saliva. In the negative control group, no lubricant was used. The combination between the wire cross-sections and the lubrication condition generated 15 groups with 15 samples each. Data were submitted to two-way analysis of variance and Tukey’s test. Results: There was no significant interaction between the wire cross-section and the condition of lubrication (p= 0.901). Irrespective of whether lubricants were used or not, there was a significant increase in friction with an increase in the cross-section of the wire (p< 0.001). For any wire, the group tested in the presence of MUC was not different from that in which HS was applied. On the other hand, when the application of lubricants was suppressed, significantly higher friction values were observed. The CMC group and the DI group demonstrated intermediate behavior. Conclusions: Friction increased with the increase of the cross-section of the NiTi archwire, but regardless of the archwire, friction with MUC artificial saliva was similar to that of HS and lower than in dry conditions.

Friction evaluation of an elastic chain positioned under or over the wire in self-ligating brackets

“…[31] e ligating method for self-ligating brackets occurs without the need for elastic or metal ligature but through clips or doors present in the brackets which, when closed, provide the sliding of the round section wire with minimal or no interaction to the linkage system. [2,6,24,32,33] In the current study, passive and active self-ligating brackets showed no statistically significant differences when using a 0.018"gauge steel wire, regardless of whether the elastomeric chain is used or not, corroborating with studies in which passive and active self-ligating brackets showed low or no resistance to friction in round section wires. [13,17,25,27,32] Depending on the gauge, section, and position of the wire in the slot, the clips of the active brackets work passively, without interaction with the wire, similar to the doors of the passive self-ligating brackets, showing similar friction results.…”

“…In this case, even with the difference between the closing system of passive and active brackets, when using elastomeric chains over the bracket/wire set, the elastomeric chain comes into contact with the wire, causing greater friction during sliding, and regardless of the wire. [5,6,12,17,25] In all situations tested in this study, the resistance to friction was significantly higher with the use of the 0.019" × 0.025" wire. ese results can be explained by the decreased area inside the slot of the bracket in the rectangular 0.019" × 0.025" wires, as they are larger in the vertical direction when compared to the round 0.018" wires, causing greater friction due to the increased surface contact of the wire corners with the inner walls of the bracket slot.…”

“…Several factors can influence the friction resistance for sliding mechanics, such as cross-sectioning and alloy composition of the wire, [1][2][3][4][5][6][7] composition and design of the bracket, [8][9][10] connection type from bracket to wire, [4,[11][12][13] and elastomeric ligatures or chains. [14,15] Among these factors, orthodontists can routinely select brackets, wires, and types of connections that can lead to smaller friction with better biological responses, allowing for benefits in orthodontic tooth movement within a shorter period.…”

Comparison of frictional coefficient and surface roughness between three different active self-ligating brackets: An experimental in vitro study

“…[2] Friction is affected by biological factor-such as saliva, debris, and biodegradation of the appliance's components that has been used-and physical factor as the using of brackets, archwires, and ligations. [3] The shape, size, and structures of the fixed appliances' components will affect the treatment result. [4] The generated forces of bracket and archwire interactions can be measured from its surface roughness.…”