Spee curve leveling with reverse curves
When we use reverse curves to level a deep curve of Spee, we find that the intrusive forces exercised in the anterior and posterior sectors are balanced with the extrusive forces that are exercised in the premolar region. Another effect is that the intrusive forces are going to provoke at the molar level a positive torque and a distal inclination of the crowns and a mesial movement of their roots; on the other hand the intrusive forces exercised at the incisor level will provoke a buccal movement of these (positive torque].
Correction of a bilateral posterior open bite with reverse curves
For the correction of this problem we can also help ourselves with the use of reverse curves. Tlie action principle of the curves, in this case, is exactly the same one that we use for the leveling of a deep Spee curve. The reactions that are produced at molar, premolar and incisor levels are the same in the upper and lower dental arches. We simply have to know how to place the reverse curves in order to have the desired effect, that in this case is the closure of the bilateral open bite. On the contrary, if we do not place the curves correctly, far from solving the problem we can complicate it even more.
1. Use of curves on both dental arches.
- Intrusion of upper and lower molars and incisors.
- Extrusion on the upper and lower premolar sector in order to level the dental arches.
- Increase in length in both dental arches
- Distal inclination of the crowns and mesial inclination of the roots in both dental arches.
- Positive torque in molars
- Positive torque at upper and lower incisor level.
Correction of an anterior cross bite with the use of a forward arch wire
For the correction of an anterior cross bite with a forward arch wire, this should only have a dentoalveolar component, and not a skeletal one. This is because the necessary forces for the correction of an anterior cross bite of skeletal origin must be greater than the ones that can be produced by a forward arch.
The forward arch is made by doing two small stops at the entrance of the molar tubes and leaving 2 mm or 3 mm of separation between the arch wire and the slot of the anterior braces. This arch wire is not only going to produce an anterior proclination for the correction of the cross bite, but will also provoke a mild molar distalization.
1. Placement of a forward arch in order to correct an anterior cross bite.
- Proclination of the upper incisors.
- Upper molar distalization.
- Positive torque in the upper incisors
- Distal inclination of the crown and mesial inclination of the roots of the upper molars.
- Posterior anchorage.
- Reduction of the nasolabial angle.