Tubes Face

FACE have Torque in the molars Another area in which the torque has been modified is that of the upper molars. Any orthodontist concerned about obtaining a functional occlusion knows that premature contacts in the second molars are very common. This is mainly due to the existence of positive molar torque, marked by “hanging” palatal cusps which interfere with the mandibular closure as it occludes with the tip of the antagonist cusps. This commonly also leads to interferences in excursive lateral movements of the jaw. The problem we face clinically is that the archwires designed for straightwire systems are commonly inefficient when correcting molar torque, even when using .021” x .025” steel archwires. Therefore, we are forced to use transpalatal bars and/or compensation bends in the archwires. One of the causes of this inefficiency is the play the archwires have in the lumen of the tubes. Several studies have demonstrated that this play is because of a slight oversizing of the bracket slots and tube lumens in addition to the fact that the archwires are often slightly smaller than stated by manufacturers and often even have rounded edges. Tests performed with tubes from several companies reveal torque losses of up to 26° with .019” x .025” steel archwires and up to 11° with .021” x .025” archwires.

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