Stage III checks

CHAPTER 19 Stage III checks

Absolute need to provide extra space 172
‘Hyperactivation’ of Side-Winders 173
The contrast with Plus 173
Causes of inadequate torque 174
Case 11 An adult Class I case with crowding treated with the Rx-1 bracket 175
Case 12 A severe Class II division 1 malocclusion with increased overbite on a very low mandibular angle Class II base treated with the Plus bracket 180

The inspection interval in Stage III is approximately 2 months. As the entire torquing and tip correcting process is essentially built-in, and self-limits automatically, progress and maintenance checks are normally all that is required; it is unusual for an archwire to require removal, except for running repairs or possibly upgrading a deep tunnel auxiliary.

At each check visit, the following should be observed:

• Progress of tip and torque. Both proceed concurrently. A Tip-Edge bracket can be seen to have self-limited when its upper and lower surfaces lie parallel to the archwire (Fig. 19.1). Always assess the root angulations as well as the brackets. Lack of progress is almost invariably due to inadequate mesio-distal space in the arch. It may also be due to incorrect bracket angulation, causing the bracket to self-limit before the desired root angle is achieved. An advantage of Plus is that all bracketed teeth are maintained in torque and tip control until the last one is finished. There is therefore no temptation to remove springs from the teeth that look finished, while waiting for the rest. This used to allow some individual root relapse, before Plus.
• Available space in the arch. Except towards the end of root uprighting, it is essential to ensure that up to 1 mm of space exists somewhere in each arch (Fig. 19.2). As explained previously, premolar and canine crowns require additional arch length as they upright, and failure to provide this will stifle the action of the uprighting, whether with Plus or Side-Winders. The procedure for introducing extra wire from the back is described presently. Tight or overlapping contacts are sure signs that a limited amount of extra space is needed to make further progress (Fig. 19.3).
• Unwanted space. More than 1 mm of space is wrong, and should be gathered up by running an elastomeric E-link from crimpable hook to molar hook. At the following visit, the relevant distal arch cinchback will need to be tightened. Excess space is caused by distal cinchbacks that are too slack.
• Condition of the uprighting auxiliaries. Distortion of nickel–titanium auxiliaries is seldom seen, since these are shielded by the main archwire. With Rx-1, Side-Winders are seldom lost, as they are retained by the elastic ligatures. However, the loops may become distorted labially, particularly if fiddled with by the patient, and should be bent back to correct shape or replaced. A labially displaced loop can predispose to a small mesio-palatal rotation.
• Activation of Side-Winders (Rx-1). These normally hold their activation without adjustment. However, final torque delivery and apical definition on incisors may require additional activation. ‘Hyperactivation’ for this purpose will be described shortly.
• Interarch relationship. Is the patient regulating the elastic wear adequately to maintain incisor contact, when in the retruded centric position? The possibility of adverse growth should be considered, but slippage of the interarch relationship almost always identifies a forgetful patient.
• The vertical relationship. Is overbite reduction and buccal segment interdigitation being preserved? Relapse of overbite in Stage III will most often be the result of inadequate archwire bite sweeps. In addition, vigorous activation of canine Side-Winders can cause overbite increase and infraocclusion of first molars, by reciprocal tipping of the archwire. This should obviously be avoided, but may require ‘Class II check’ elastics to rectify (Fig. 19.4).
• Molar widths. These will be well controlled by the rectangular archwires. However, in cases where crossbite correction is continuing into Stage III, an archwire may possibly need removal to check width and further adjust, or cancel, active molar torque.
• Second molars. Towards the end of Stage III, the position and function of second molars will need assessment, with a view to alignment if required. This is outlined in the following chapter.
• Profile considerations. This may require confirmation with cephalometric assessment. Is anchorage reinforcement required? A less than ideal profile may be the result of adverse growth or an inappropriate treatment plan. Too procumbent a profile may also be provoked by excessive activation of Side-Winders, particularly on canines. This is not likely with Plus, using only a .014 inch tunnel wire.
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Fig. 19.1 A Tip-Edge bracket has fully expressed when its occlusal and gingival tie wings have become parallel to the rectangular archwire.

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Fig. 19.2 A very small amount of space somewhere in the arch is necessary to allow freedom of uprighting, unimpeded by tight contacts.

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Fig. 19.3 Tight contacts and anterior rotations (in this Rx-1 case) are indicative of inadequate space during root uprighting.

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Fig. 19.4 Class II check elastics can be a useful aid in maintaining overbite reduction, or promoting molar occlusion.

Absolute need to provide extra space

This is the most common adjustment needed during Stage III and takes only a few moments to perform. Except when premolar and canine uprighting is almost complete, a very small amount of free space should be available in each arch, to give the crowns the extra ‘elbow room’ they require as they upright.

The method used is very much the same as described under ‘cinchbacks’ in the last chapter. First, the four incisors should be released from the archwire by removing the modules. The tapered tips of a light wire plier should then be inserted in the contact mesial to the molar band, grasping the archwire immediately mesial to the buccal tube, before gently rotating the handles forward (Fig. 19.5). Only about half a millimetre of wire will need to be fed through from each side. This needs to be observed carefully. The easiest way to do this is to watch the crimpable hook; the slightest forward movement will be sufficient. The elastomeric modules can then be replaced, which will gather the incisors fractionally forward. During the early part of the third stage, and particularly in extraction cases, it is common to have to repeat this simple process at later visits.

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Fig. 19.5 Admitting a small amount of extra space during Stage III, by feeding half a millimetre of wire forward through the molar tube. The incisor ligatures should be removed first.

‘Hyperactivation’ of Side-Winders

This is included here for the benefit of Rx-1 users. It was described in the previous edition of this book as only ever required towards the end of treatment, on selected teeth. The aim is to facilitate the delivery of the final torque prescription, also to increase bodily control, where required, for anchorage purposes. In practice, this refers to />

Related posts:

  1. Differential tooth movement
  2. Precision finishing
  3. Introduction
  4. Stage II checks
  5. Dynamics of Tip-Edge
  6. Stage I

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Dec 31, 2014 | Posted by in Orthodontics | Comments Off on Stage III checks

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