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REFINED BEGG SUB-STAGE I B

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objectives

Bite opening: The emphasis generally is on incisor intrusion and on minimizing molar extrusion as much as possible. Retraction of the upper anterior teeth. Control of the mandibular plane angle. Matching the u/L midlines. Correction of inter-arch relation. Displacements and rotations of the premolars are corrected.

Duration of substage I-B will be 4-6 months

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Sub stage I B forms the major part of the first stage. Arch wires used are the standard 0.018 p† or p wires. The elastics employed are mostly ultra light class II or light. BITE OPENING: The preference during bite opening is for incisor intrusion and for avoiding molar extrusion. In refined begg, excess proclination or retroclination of upper incisor is corrected initially. Then the intrusive and cl. II elastics forces are varied, depending on the changing inclination, so that orientation of the resultant force is kept close to C. Res of upper incisor and more or less parallel to their long axis.

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1. Initially, the intrusive force applied is about 45 gm, while the cl II elastic force is about 60 gm in the case of severly proclined incisor. The resultant of two passes a little behind the C. Res and slightly diverging away from the long axis of the teeth. It mainly reduces proclination but causes little intrusion

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2. As the inclination improves, the intrusive force is gradually increased to about 60 gm, while the cl. II force is reduced till it reaches 30gm on each side. The resultant will be more parallel to long axis and near to C. Res. It brings about further improvement in inclination and some more intrusion. In subsequent visits intrusive force is gradually increased to 90gm.

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3. As the incisors become more upright, the elastics application is changed to an oblique direction. The resultant from such combination gets more oriented even more vertically and thus more parallel to the long axis of the teeth. It not only reduces the incisor inclination by controlled tipping but also is adequate in magnitude to bring about active intrusion of the incisors. The direction change is effected by changing the Cl. II orientation to Cl. I orientation and subsequently by applying the elastics from the T.P.A. in a direction anteriorly pointing downwards. Another way to do this is to use power arms.

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In severely retroclined upper incisors as in cl. II div.2 situation, the case is started with usual anchor bends, with the concomitant use of cl. II elastics. Only those teeth that are retroclined are bracketed, and arch wire is engaged in their brackets. The intrusive force acting alone passing in front of C. Res of these teeth corrects their retroclination, and also causes some amount of intrusion. As they get uprighted, other anterior are bracketed, and wire is engaged in all the brackets. Elastics are started only after incisors become favorably inclined. www.indiandentalacademy.com


LOCATION OF BITE OPENING BENDS AND MODIFICATIONS

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Many authors have proposed different sites for bite opening bends in the archwires.

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Any bite opening bend or curvature in the archwire divides it into segments that is no longer parallel to occlusal plane. Therefore when these segments are engaged in the brackets, they exert reciprocal intrusive or extrusive effects. But Bowing of the archwire complicates this:

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1. The conventional bite opening bends placed 3 mm mesial to the molar tube, tend to cause more intrusion of canine then incisors due to bowing of archwire in the canine area.

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Gable bends placed distal to canines (normally made in the third stage to maintain bite opening) tend to cause a relative extrusion of canines. While there is progressively more intrusion of incisors.

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With Hocevar modification, the central incisor are subjected to intrusion while the canine and lateral incisor are both extruded with respect to central incisor.

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With biteopening curve and kameda’s modification, the canines are extruded while the lateral and central incisor experience progressively more intrusive effect.

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So to bring uniform intrusion following archwire modification is recommended: A mild gingival curve is incorporated in the anterior section from mesial of one cuspid circle to the corresponding point on the other side. This should lift the archwire at the midpoint by 3 mm.

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The correct way to bend the gingival curve is as follows: After anterior portion of archwire is shaped and cuspid circles are formed as usual, two small equal bends are placed, on each just mesial to both the cuspid circles. Although this gives the appearance of an anterior gingival curve, it also would have caused an inward tilting of the cuspid circles as well as the posterior sections of the archwire. Then, using an arch forming plier facing downwards, the anterior portion of archwire is again curved, starting from the midline and proceeding to both the sides till the cuspid circles are parallel to the plane of the archwire.

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Further intrusive action of gingival curve is enhanced by incorporating a vertical step bend 4-5 mm in height and placed 2-3 mm mesial to the molar tube on both sides. Anchor bends of required degree is placed at the end of the step.

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In actual practice, the step up bend is made about 5 mm in front of the molar tubes. When the tip back bend is made and the arch wire is brought down from the vestibule to the incisor brackets, it pushes the step up bend distally by about 2 mm.

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II. ELIMINATION OF OVERJET MAINTAINING CONTROL OVER THE ROOT POSITIONS OF ANTERIOR TEETH

Overjet was reduced in the conventional Begg by the use of Cl II elastics till the anteriors attained an edge to edge relation, this often resulted in uncontrolled tipping of the upper anteriors.

While the refined Begg also aims at the anterior edge to edge relation, and uses CL. II elastics to attain it, it is done by avoiding uncontrolled tipping

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A. CONTROLLED TIPPING OF THE UPPER INCISOR DURING RETRACTION. To prevent uncontrolled tipping of the anterior segment during retraction by the use of CL. II elastic, a counter moment must be provided such that the ratio of counter moment to the retractive component of CL. II force lies in range between 5:1 and 8:1 mm. It is also well known for the long time that a certain balance of the intrusive force and light CL. II elastics could maintain the positions of upper incisor root apices during retraction. This can be explained by the fact that the intrusive force itself creates the counter moment that is required for controlled tipping. But in conventional Begg the intrusive force was comparatively low and the elastics used were relatively heavy. Thus the use of higher intrusive forces and light or ultra light elastic forces in the sub stage I B is essential for both incisor intrusion as well as controlled tipping. www.indiandentalacademy.com


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B. PREVENTING UNCONTROLLED TIPPING OF LOWER INCISORS. During bite opening the lower incisors tend to procline by uncontrolled tipping. This is prevented in one of the following ways: 1. In severe deep bite cases, there is a heavy contact of the incisal edges of lower incisors with the palatal surface of upper incisors or with the palatal mucosa. This contact prevents labial movement of the lower incisor crowns during initial phase of bite opening. 2. Lower incisor brackets are bonded as far gingivally as possible. Anchor bends in the lower arch of lesser degree than in the upper arch, since lesser amount of intrusive force is used on the lower than on the upper teeth. Both these measures reduce tipping tendency of the lower incisor.

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3. A MAA with labial root torque is used on the lower incisors during stage I.

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4. The ends of lower arch wire are bent distal to the molar tubes, as recommended by Hocevar. This helps in minimizing the tipping of lower incisors.

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C. ROOT CONTROL DURING CORRECTION OF EXTREME LINGUAL OR LABIAL POSITIONS OF THE ANTERIORS. 1. Labial root movement of the instanding incisor or canines is initiated during the sub-stage IB by using a MAA auxiliary. If a stronger torquing force is required for a canine that is moved a large distance labially from a palatally impacted position, a torquing auxiliary is used from the molar tooth on the same side, after supporting the molars with a T.P.A. www.indiandentalacademy.com


2. Lingual root movement of the canines having very marked root prominence is needed for placing them into cancellous bone. Otherwise, intrusion and retraction of the anteriors is hampered. This is done using the Jenner’s auxiliary.

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3. If the adjacent lateral incisor and canine teeth need reciprocal torque, a “spec” auxiliary is used.

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III. Controlling the mandibular plane angle. The mandibular plane angle can open during treatment due to molar extrusion, causing a worsening of CI. II profile. This is more likely to happen in high angle cases with a weak massetric sling. The culprits invariably are strong anchore bends and heavy CL. II elastics. These should be avoided in such cases. Other adjuncts like T.P.A. or a high pull headgear on upper molars can help in controlling their vertical positions. Bite blocks can also be used to prevent over eruption of the upper and lower molars.

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IV. CORRECTING THE MIDLINE DISCREPANCY. Some amount of midline correction would have occurred during the alignment phase. Thereafter, the upper midline correction is done using slightly uneven CL. II elastic force on the two sides (stronger elastic on the side to which midline is to be shifted) till it gets corrected. If both the midlines are shifted in the opposite directions, a midline diagonal elastic ( from the upper right cuspid circle to the lower left, or from the upper left cuspid circle to the lower right) is used along with CL. II elastics.

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If the lower midline alone is deviated, it is corrected by using a unilateral lower CL.I elastic. When the deviation is significant, an uprighting spring is added on the opposite canine, which provides a pushing force to supplement the pulling force from a Cl. I elastic on the other side.

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arch wire for both the above situations are made of .018

P+ wire. Hence in spite of the uneven vertical components of elastics on the two sides the occlusal plane is maintained.

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V.CORRECTING THE INTER-ARCH RELATIONSHIP TO CL. I. a. In a growing child, correction of molar and canine relation from CL. II to CL.I is mostly achieved by encouraging the mandibular growth. In few patients, unlocking of the occlusion during bite opening coupled with the action of Cl. II elastics has a functional appliance like effect. In other cases, a functional appliance such as EVAA is required along with the fixed mechanotherapy. b. Mesial movement of the lower posterior dental segment with respect to the upper, brought about by the action of Cl.II elastics, plays a minor role in the treatment of growing children whereas it plays a major role while treating adults. c. In selected cases, the Cl. II molar relation is corrected by distalizing the upper molars.

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CHECKLIST AT THE END OF STAGE I. The incisors are in edge to edge relation, midlines are matching and the canines are in CL. I occlusion. Anteriors are well aligned and in good contact. The upper and lower arch forms are matching. Molar rotations and bucco-lingual displacements are corrected. Good control is maintained over the root positions and the mandibular plane angle. The molar relation is usually in Cl. I.

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SUMMARY OF THE ELASTICS USAGE IN THE STAGE I ď Ž

1. Light or ultra light class II elastics are frequently used. They are meant for retraction of upper anterior teeth after overcoming the labial flaring effect of the bite opening archwire, as also for the sliding of upper canine to unravel upper crowding, when required. They tend to protract the lower posterior teeth and extrude the upper anteriors and lower molars. Hence light or ultralight elastics should be used.

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2. Upper palatal elastics or elastics from power arms soldered to the upper molar bands are used when true intrusion of upper incisors is desired. They intrude as well as retract upper incisors.

3. Lower CL. I elastics are used for unraveling crowding of the lower anteriors.

4. Upper CL. I elastics are seldom used, only indicated when a super CL. I or CL.III molar relation due to mesial drift of the lower molars, usually on account of premature loss of teeth mesial to them.

5. Uneven CL.II, CL.I or midline are indicated for midline correction. www.indiandentalacademy.com


PINS IN THE SUB STAGE I B.

Excess freedom is only needed during sub stage I A till the anterior teeth have to slide against the wire either the to open the space or to close the space.

Thereafter such freedom not only results in excess tipping, but also can affect the rotational control.

Hence stage III pins are engaged as soon as teeth are properly aligned and in good contact.

Hook pins and high hat pins can also be used.

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ANCHORAGE CONSIDERATIONS IN THE STAGE I

The term Anchorage usually refers to the resistance to undesired movement.

In refined Begg elastics used are light or ultralight elastics.

Class I elastics are rarely used and when the molars should be stabilized with the T.P.A.

In the lower arch stiff archwire is used 0.018 P+ OR P followed by 0.016 and 0.014. stronger elastics are seldom used during this stage.

Lip bumper in the lower arch may be used for reinforcing the anchorage. www.indiandentalacademy.com


Loss of anchorage in vertical direction in the form of extrusion of molars occurs due to the vertical component of CL. II elastics and the anchor bends in both arches.

Normally masticatory forces provides resistance to molar extrusion.

T.P.A., high pull headgear, posterior bite blocks can also be used.

TRANSERVES anchorage to prevent lingual rolling of the molars is obtained by using sufficiently stiff archwires. T.P.A. and suitably expanded headgear face bow or lip bumper may be used if necessary.

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