Psedo. Class 3 malocclusion management:
1- Ant advantage of upper ant teeth
2- Restriction of lower arch ***
3- Lip bumper.
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Dental rotations are very frequent in all malocclusions that we treat with fixed appliances. Using various systems for correction and in different phases of treatment. Although it may seem that the rotation of a premolar can be corrected with the same system as that of a lateral one, the control of the movement and the levers necessary to perform it must be different in order to achieve an acceptable efficiency with our apparatus.
Rotation correction can be done with 3 basic systems:
1- Elements external to the straight arc apparatus (quad-helix, Goshgarian bar, etc.).
2- Auxiliary devices supported by brackets or arches.
3- Elasticity of the arch that presses on the bracket.
When discussing the effectiveness of a technique, we usually talk about the third correction system and this bracket-arc ratio is usually optimized for the correction of rotations to the detriment of other actions in this set. For example, increasing the width of the bracket, decreasing the clearance in the groove and increasing the angle of support, improve the efficiency of the rotation correction by increasing friction and therefore, hindering other aspects of the correction such as the alignment, distance of canines or closing of spaces.
The latest developments in low friction or self-ligating brackets have reduced friction by presenting a great difficulty in correcting rotations by deflecting superelastic arcs, which has caused the appearance of new arc profiles that try to alleviate this problem in some way. The problem of the correction of rotations can be easily solved following criteria of choice of the correction system according to the dental zone, the magnitude and the space available for the correction.
One of the greatest difficulties that the correction of rotations presents is precisely their stability, there is a high tendency to relapse after their correction1. They have tried to develop methods as preventive measures to this fact such as increasing retention periods, overcorrecting the rotation taking into account that they will recur for the corrected tooth (s) aligned, make an early correction of the rotations before the root formation is completed, this is that the intestability of the rotations are due to the transeptal fibers that join the tooth to the alveolar bone, they are fibers that are very hard restructured and therefore when we stop applying a mechanic, they tend to return to its original form and position causing dental movement. Already in 1958, Reitan proposed to perform a surgical sectioning of the gingival fibers after the correction of the rotation so that they healed and consolidated in the new position, thus reducing instability2. Other studies have shown that this method is not entirely effective1.
ROTATION CORRECTION PHASES:
The rotation correction is not performed simultaneously in all dental areas, but we follow consecutive phases, optimizing the system for each of them.
1- Correction of molars:
Intense molar rotations are corrected prior to the assembly of the fixed apparatus, to avoid relying on adjacent teeth. Once the rotation with 2 or 3 activations of a Gosgharian bar is improved, we remove it and continue the treatment with Nickel Titanium arches. We do not use active bars and fixed appliances because of the difficulty in coordinating the palatal bar and the arches. In figures 1, 2 and 3 we show an example of the improvement obtained with the palatal bar prior to the placement of the fixed apparatus.
2- Correction of incisors:
The upper incisors can be corrected with superelastic arches, due to the great interbracket distance they present. The space occupied by the incisors, smaller when they are rotated, forces to obtain, beforehand, to correct enough space so that they can be aligned.
Initially, we performed the correction of rotations with round wires to avoid increased friction and unwanted effects of rectangular wires, incorporating the torsion of the dental crowns once the incisor was broken.
In the lower incisors we have more limitations for the correction of rotations, due to the shorter mesio-distal distance, leaving a very short or sometimes non-existent wire length (the bracket touches the adjacent one) that prevents the deflection of the wire without deforming it. This problem is greater the greater the width of the brackets. The use of auxiliary devices facilitates correction to allow elastic deformation of the wire.
3- Lip bumper.
-----------------------------
Dental rotations are very frequent in all malocclusions that we treat with fixed appliances. Using various systems for correction and in different phases of treatment. Although it may seem that the rotation of a premolar can be corrected with the same system as that of a lateral one, the control of the movement and the levers necessary to perform it must be different in order to achieve an acceptable efficiency with our apparatus.
Rotation correction can be done with 3 basic systems:
1- Elements external to the straight arc apparatus (quad-helix, Goshgarian bar, etc.).
2- Auxiliary devices supported by brackets or arches.
3- Elasticity of the arch that presses on the bracket.
When discussing the effectiveness of a technique, we usually talk about the third correction system and this bracket-arc ratio is usually optimized for the correction of rotations to the detriment of other actions in this set. For example, increasing the width of the bracket, decreasing the clearance in the groove and increasing the angle of support, improve the efficiency of the rotation correction by increasing friction and therefore, hindering other aspects of the correction such as the alignment, distance of canines or closing of spaces.
The latest developments in low friction or self-ligating brackets have reduced friction by presenting a great difficulty in correcting rotations by deflecting superelastic arcs, which has caused the appearance of new arc profiles that try to alleviate this problem in some way. The problem of the correction of rotations can be easily solved following criteria of choice of the correction system according to the dental zone, the magnitude and the space available for the correction.
One of the greatest difficulties that the correction of rotations presents is precisely their stability, there is a high tendency to relapse after their correction1. They have tried to develop methods as preventive measures to this fact such as increasing retention periods, overcorrecting the rotation taking into account that they will recur for the corrected tooth (s) aligned, make an early correction of the rotations before the root formation is completed, this is that the intestability of the rotations are due to the transeptal fibers that join the tooth to the alveolar bone, they are fibers that are very hard restructured and therefore when we stop applying a mechanic, they tend to return to its original form and position causing dental movement. Already in 1958, Reitan proposed to perform a surgical sectioning of the gingival fibers after the correction of the rotation so that they healed and consolidated in the new position, thus reducing instability2. Other studies have shown that this method is not entirely effective1.
ROTATION CORRECTION PHASES:
The rotation correction is not performed simultaneously in all dental areas, but we follow consecutive phases, optimizing the system for each of them.
1- Correction of molars:
Intense molar rotations are corrected prior to the assembly of the fixed apparatus, to avoid relying on adjacent teeth. Once the rotation with 2 or 3 activations of a Gosgharian bar is improved, we remove it and continue the treatment with Nickel Titanium arches. We do not use active bars and fixed appliances because of the difficulty in coordinating the palatal bar and the arches. In figures 1, 2 and 3 we show an example of the improvement obtained with the palatal bar prior to the placement of the fixed apparatus.
2- Correction of incisors:
The upper incisors can be corrected with superelastic arches, due to the great interbracket distance they present. The space occupied by the incisors, smaller when they are rotated, forces to obtain, beforehand, to correct enough space so that they can be aligned.
Initially, we performed the correction of rotations with round wires to avoid increased friction and unwanted effects of rectangular wires, incorporating the torsion of the dental crowns once the incisor was broken.
In the lower incisors we have more limitations for the correction of rotations, due to the shorter mesio-distal distance, leaving a very short or sometimes non-existent wire length (the bracket touches the adjacent one) that prevents the deflection of the wire without deforming it. This problem is greater the greater the width of the brackets. The use of auxiliary devices facilitates correction to allow elastic deformation of the wire.
3- Correction of canines:
The canine when presenting a very voluminous root with respect to the premolar and lateral, generates a great resistance to the movement by the great support in the alveolar bone transmitting the forces applied on it to the adjacent teeth. For this fact, for its correction we must distribute the force of defeat in a dental group. The use of mesial and distal canine handles, in addition to facilitating its correction, can be used as support for different auxiliary devices.
The rotation of the canine and the vestibulo-lingual compensation (in-out) incorporated in the prescription, especially in cases of extractions, is modified by each author to look for certain objectives in the effectiveness of orthodontic treatment. The greatest variation in all prescriptions is found in these two aspects, extremely important for finishing, reaching the extreme of preventing a correct alignment of the contact points if special care has not been taken. The prescriptions designed to give hypercorrection at the termination (Roth) incorporate a rotation in the base of the bracket that misaligns the contact points in the opposite direction to the most frequent recurrence in cases of extraction.
4- Premolar correction:
The premolars occupy more space when they are rotated and their root anatomy makes it difficult for the lever action performed by the bracket / arch assembly. It is necessary to use auxiliary devices supported by a rigid arc to achieve treatment efficiency by generating a couple of forces (See figures 11 and 12).
5- Precise adjustment in the correction of incisors:
The variety in the dental anatomy of the incisors and the influence of small rotations in the aesthetics of the anterior front require an individual adjustment to each patient, before the removal of the device. This third phase of termination and individualization is the one that we spend the most time during the treatment. On many occasions after a complete study we change the prescription of brackets, the type of these (wider), the position and the final arches with the shape of an individual arch.
Just as we do not agree that a different prescription is more effective for each type of malocclusion, we do believe that for termination it is necessary, on many occasions, to change the type of bracket we use to attach it to the best final fit.
6- Rotation retention:
Once the correction of the rotation is finished, we must maintain the position obtained for a long period of time, building a plate with the perfectly adapted vestibular arch, with acrylic support in the palatal area of the tooth.
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