Chulalongkorn University Dental Journal

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Background/objectives This study aimed to investigate the effect of one or two brackets on orthodontic frictional forces and to compare frictional forces of posterior segments when a molar tube had different degrees of tipping. Materials and Methods Five different types of posterior segment templates with six templates per type were constructed. Templates A and B had one and two brackets with an untipped tube, respectively. Templates C, D, and E had two brackets and a 3°, 6° or 9° tipped tube. Each template was coupled with 0.016″ x 0.022″ stainless steel wire and ligated with elastomeric ligatures. Static frictions were determined to compare the resistance to sliding in dry condition. Results The mean static friction of all templates was statistically different among groups. An additional premolar bracket in the untipped tube templates increased the friction from 103 ± 64 gram to 156 ± 15 gram. The 3°, 6° and 9° tube/wire angulation generated 235 ± 33 gram, 329 ± 49 gram, and 489 ± 63 gram of friction, respectively. Conclusions This study demonstrated that the number of brackets and tube/wire angulation affected the total resistance. By changing from one to two brackets, the static friction increased 50 gram. Moreover, as little as 1.6-degree tube/wire contact angles above a critical angle generated 80 gram of binding. Thus, the high tube/wire angulation should be avoided when the low frictional force is needed, and vice versa.



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