Mandibular arch treatment

Mandibular arch treatment usually is initiated 4 to 6 months after maxillary arch treatment has begun. When the maxillary arch is under control, the mandibular teeth are more fully erupted (especially second molars, if possible), and the mandibular orthopedic response is taking effect. The mandibular arch is now ready for appliance placement.

Treatment in the mandibular arch is not always delayed. The rule is to band and bond the mandibular arch when the canines are in a Class I relationship. This means that Class III patients and Class I patients with bimaxillary protrusion may begin treatment in the mandibular arch early.

When the time comes to begin treatment in the mandibular arch, emphasis is given to controlling the anterior teeth immediately. The mandibular arch should be treated aggressively from the day it is bonded and banded. If possible, a 0.017 x 0.025-inch braided stainless steel wire or a rectangular nickel-titanium wire is placed as the first archwire, to eliminate rotations and begin leveling the arch while maintaining torque control in the anterior dentition. The archwire selected is dependent on the degree of crowding. In a routine case where there is less than 4 mm of anterior arch length discrepancy and the goal is to hold the incisors in their original positions, the aforementioned scenario will suffice.

A greater discrepancy or the need to upright the incisors may require one or both of the following:

1.  Slenderizing followed by a 0.016 x 0.022-inch nickel-titanium wire or a round 0.016-inch nickel-titanium or stainless steel archwire

2.  Controlled use of class 3 elastics

After 2 to 4 months, if needed, a rectangular titanium-molybdenum alloy wire or a 0.016 x 0.022-inch stainless steel wire is used as an intermediate wire to continue torque control, correct rotations, and for leveling. These wires are constructed with omega loops and tied back to eliminate dental drifting and space opening. In most cases, a reverse curve of Spee is incorporated to help level the mandibular arch.

At times, if the initial braided stainless steel wire has performed nearly all the required alignment, leveling, and rotation correction, the finishing archwire (0.017 x 0.025-inch stainless steel) is placed immediately following the braided stainless steel wire.

Class 2 elastics and/or midline elastics are employed after the finishing archwires (0.017 x 0.025-inch stainless steel) are in place on both arches to finalize any Class II correction. The total treatment time, depending on growth and compliance, is approximately 18 to 24 months.

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