Despite the sophisticated prescription appli- ances currently in common usage, there are minor adjustments that can be incorporated into the final stages of treatment, which con- tribute to improving the functional and aes- thetic features of the final occlusion. Apart from clinical evaluation of the occlusion, it is at this stage that pre-completion radiographs, dental panoramic tomograms (DPTs) and cephalographs need to be taken to assess root parallelism, anterior root torque, root resorp- tion, position and angulations of unerupted third molars and the possible development of any other anomalies. Radiographs taken at this stage still allow for the possible corrective procedures to be instituted as opposed to radiographs taken after the removal of appli- ances.
As you near the end of active treatment tell your patients, particularly adult patients, that as the treatment is approaching the final stages, you would like them to start checking their teeth periodically in the mirror and to make a note of any feature about which they are unhappy. They need to let you know at the next appointment.
Pearl: The patient may see a feature or have
a perception of their teeth of which you are unaware; it is far preferable to be in a posi- tion to correct this particular feature or per- ception prior to the removal of appliances.
Final Detailing of the Occlusion
Luc Dermut
As an aid to final detailing of the occlusion, it helps to have an overall view of the entire dental arch. To get a better view of the dental arch use a large mouth mirror (No. 6) or the occlusal mirror used for intra oral photogra- phy.
Progress study models also help to identify errors and details that need to be corrected.
ANTERIOR SEGMENTS
From the patient’s point of view, the aesthetic component of the final occlusion is of greater significance than the functional component. It is incumbent on you, the clinician, to also eval- uate and correct the functional component.
Angulation of Anterior Teeth
The centrals, laterals and canine teeth should all have a mesial tip. While this feature may be built into the bracket prescription, it is pos- sible that an incorrect placement of the bracket at the initial strap-up will only start to express itself as an incorrect tip when the final arch- wires fully express the bracket prescription. It is a common fault to leave the lower lateral incisors either upright or with a distal tip. If there is a problem with tooth angulation it may be corrected by:
• Repositioning the bracket and correcting for tip
Apart from the input given by your patient, there are a number of features you need to examine carefully as you approach the end of active treatment. As you examine the denti- tion it is a good idea to bear in mind Andrews’ six keys of occlusion.1
• Placing corrective bends in the archwire • Using an uprighting auxiliary.
Alignment of Incisal Edges
Look carefully at the incisal edges, check for chipped or excessively worn incisal edges. Marked incisal mamelons may also be aes- thetically unacceptable. The incisal edges of the four maxillary incisor teeth should be in the same horizontal plane or the lateral incisors slightly palatal to the central incisors, the maxillary lateral incisal edges should be 0.5 mm (0.2 inch) shorter than the central incisors. This arrangement contributes to a more youthful smile, but placing the four maxillary incisors at the same vertical level ages the smile. When the patient smiles the incisal edges of the maxillary anterior teeth should curve and follow the smile line of the lower lip.
Check the horizontal cant of the occlusal plane, ask the patient to close on a flat tongue depressor (flat wooden blade) held across the front of the mouth. Check the level with the rest of the face with particular reference to the inter-pupillary line.
Correcting the levels of the incisal edges can be done by:
• Repositioning the brackets to correct for vertical height discrepancies.
• Adjusting the archwires using vertical off- set second order bands.
• Selective grinding of the incisal edges with a mounted stone or diamond burr. Minor artistic grinding or reshaping of the incisal edges, particularly the mesial and distal incisal angles, can make a tremendous dif- ference to the final smile. If you use a slow handpiece, then support the tooth with fin- ger pressure to reduce the sensation of vibration.
• Aesthetic composite bonding can also mask certain anatomical deficiencies. You have the choice of either carrying out this procedure yourself or requesting the patient’s dentist to do the bonding accord- ing to your prescription.
Recontouring Technique
Richard N Carter
In my adult practice, I re-shape and make slender some teeth on virtually all patients.2I
have found a thin, double-sided diamond disc can be bent slightly to contour the teeth, not just flatten them. The procedure is fast, pain- less, clean, and simple. It can be done at any stage of treatment. Remove the archwire first.
With a flexible disc it is easier to round the incisal edges than using a burr, a flame- shaped diamond, or a wheel. After any re-con- touring, polish with an abrasive-impregnated wheel. These wheels are very soft and will last for only a few teeth, but this softness is the secret for attaining a beautiful, smooth surface while removing a minimum of enamel.
Torque of anterior teeth
Check for expression of the correct torque for all the anterior teeth. Examine the anterior crowns from the front and the side. It is also helpful to examine the maxillary teeth from the palatal aspect and the mandibular incisors from the lingual aspect.
Pearl: Look at the palatal and lingual gingival
margins; uneven torque will show up clearly.
Inadequate labial root torque of initially palatally displaced maxillary lateral incisors will become more obvious when the palatal aspect is examined. Surgically exposed impacted maxillary canine teeth also need to be evaluated for adequate labial root torque. Uneven torque between central incisors may be due to abnormal crown anatomy or failure to seat the bracket flat on to the labial surface at the time of the initial bonding. Uneven or inadequate torque can be corrected by:
• Repositioning the bracket.
• Incorporating torque adjustments into the archwire or by using individual or multi- ple, palatal or labial torquing auxiliaries (Chapters 9 and 10).
Rotations of anterior teeth
Rotations are notorious for their relapse ten- dency.
Facial and dental centre-lines
Check the maxillary and mandibular centre- lines. They should be coincident with each other and with the facial centre-line. Centre- line discrepancies may be due to many dental or skeletal factors and in certain cases accept- ing a centre-line discrepancy may be unavoid- able.
Pearl: It is advisable for all rotations to be
corrected to ideal or slightly over-corrected positions in the early stages of treatment. The longer the rotated teeth are held in the correct position, the greater the chances of stability.
If you correct a rotation just before the end of treatment, there is a good chance that this will relapse very quickly after the removal of appliances. Irrespective of how good your memory is, you cannot recall the original position of the teeth. Therefore, to assess whether all rotations have been correctly managed, it is essential to have either the original study models or clinical photographs at hand.
Pearl: The mesio-labial rotations of maxillary
lateral incisors in Class II division 2 maloc- clusions should be slightly over-corrected; they relapse very easily.
Rotations can be corrected by:
• Incorporating mild artistic palatal offsets into your final archwire. Maxillary lateral incisors should generally be fractionally more palatally placed than the central incisors.
• Offset the bracket base on the tooth surface either at the time of initial bonding or as a corrective measure during treatment. To create a predictable base offset, spot-weld a small piece of 0.356 mm (0.014 inch) wire to the mesh base at either the mesial or distal edge of the bracket base as the case requires.
• Rotation wedges are fairly efficient on flat surfaced teeth but not on curved canine and pre-molar teeth.
• If the brackets incorporate vertical slots, clockwise or counter-clockwise rotation springs are efficient, they may be made in- house or purchased commercially (TP Orthodontics Inc, USA).
Pearl: However, if you planned for the centre-
lines to be coincident, then it is essential to see that this has been achieved some time prior to completion before all available space has been closed.
If the centre-line needs to be corrected as you approach the end of treatment, then this can only be achieved by:
• Mild tooth tipping of selected teeth in one or both arches. If the correction requires bodily tooth movement, then this should have been carried out earlier on in treat- ment.
• The use of anterior diagonal elastics as well as unilateral Class II or Class III elastics can achieve mild tipping. Or if your brackets incorporate vertical slots, unilateral uprighting springs will assist in tipping teeth and correcting centre-line discrepan- cies.
Whatever method you choose, if you want the teeth to tip at this late stage you will need to reduce archwire thickness; with full thick- ness archwire engagement, the teeth will not tip.
It is assumed that overjet and overbite have been adequately corrected with due regard to the original malocclusion. The overbite should provide adequate incisal guidance and pos- terior disocclusion on mandibular protrusion.
Closing a Small Diastema
Ronald G Melville
If a patient has been scheduled for removal of appliances and you notice that there is still a
small midline diastema, you are faced with three choices:
1. Both you and the patient accept the space and all appliances are removed.
2. Or the two central incisors are tied with an elastomeric thread and a new appointment is scheduled for the removal of appliances. 3. Or take two lengths of band material
(stainless steel tape) folded over two or three times and force it between the cen- trals and the lateral incisors on each side. This will close a diastema of about 0.50 mm (0.02 inch) instantly. A fixed palatal retainer can be bonded to hold the central incisors together. The lateral incisors ‘spring back’ so no gaps are left between them and the central incisors (Figure 11.1a, b, c).
POSTERIOR SEGMENTS
When evaluating the posterior segments, it is incumbent on you, the clinician, to examine and correct the details of the buccal occlusion irrespective of the patient’s perceptions regarding their significance. Patients gener- ally are not too concerned about the aesthetic or functional features of the buccal occlusion.
Root Parallelism
Check to see that all the buccal teeth are upright and the roots are parallel, particularly on either side of an extraction site.
Pearl: In second pre-molar extraction cases,
special attention needs to be paid to upright- ing distally tipped first pre-molars and mesially tipped first molars.
Failure to achieve this parallelism will be due to incorrect bracket placement or failure to reach full thickness archwire engagement in relation to bracket slot size. Correct this fault by:
Figure 11.1
(a) Small residual midline diastema. (b) Stainless steel band material (tape) placed as a wedge between the cen- tral and lateral incisors, note the closure of the diastema. (c) The wedges are removed after placing a lingual retainer to hold the central incisors, the lateral incisors move back into contact with the central incisors.
(a)
(b)
• Repositioning the relevant brackets and introducing the correct tip.
• Re-bending the archwire placing corrective second order bends.
• If the brackets incorporate vertical slots, place the correct uprighting or sidewinder springs.
If molar teeth have been moved distally as part of the original treatment plan, check to see that they are not left with a distal crown tip. Distal molar tip, particularly of the maxil- lary molars, will relapse and what looked like a Class I molar occlusion will relapse to a cusp-to-cusp Class II relationship. Molar teeth can also finish with either a mesial or distal tip due to poor initial buccal tube placement. Try to seat the disto-buccal cusp of the maxil- lary first molar down into the embrasure between the mandibular first and second molars.1 To correct poorly tipped molars, it
will be necessary to:
• Place corrective second order bends in the archwire.
• Reposition the buccal tubes. The maxillary first molar will have a slight mesial crown tip. If the case finishes with a Class II molar relationship, the maxillary first molar will need to be more upright.
Premolar rotations
These rotations should be carefully checked in relation to the original malocclusion; rotations should be slightly over-corrected. Con- ventional bands on pre-molars generally incorporate buccal brackets and lingual but- tons; this arrangement makes it easy to rotate pre-molars, using palatal and buccal elas- tomeric threads. The presence of a lingual button on a pre-molar tooth also provides the facility for a lingual ligature tie, which can be used to hold the rotation throughout treat- ment. With the current replacement of con- ventional bands by brackets bonded only to the buccal surface, correcting rotations becomes more difficult and unfortunately in certain cases, may be overlooked.
If detected, rotations can be corrected before finishing by:
• Repositioning the bracket to aid in over- correction if desired.
• Bonding a lingual button and placing elas- tomeric threads to create a rotational cou- ple.
• Use clockwise or counter-clockwise rotat- ing springs if vertical slots are present. • Although not very efficient on curved teeth,
rotation wedges can assist. Molar rotations
At the end of treatment maxillary first molars should exhibit a mild mesio-buccal rotation.
Pearl: Poor initial bracket placement will also
lead to poor rotation control.
Pearl: Unfortunately, it is not uncommon in
an extraction case or in a case exhibiting ini- tial generalized spacing, for the molars to result in mesio-palatal rotation due to the action of buccal space closing mechanics.
Undesirable molar rotation can also occur as a result of using molar tubes with no distal off- set, or placing the buccal tubes either too far mesially or distally. To correct the rotation of the molars:
• Final space closing should be carried out using an elastomeric chain or thread from a palatal cleat or button on the molar to a hook on the main archwire placed between the canine and lateral incisor.
• If necessary, reposition the buccal tube, or replace it with a tube having the correct distal offset, this will vary with the appli- ance prescription.
• It is also possible to correct molar rotations by placing toe-in or toe-out bends in the main archwire.
Lower molars should exhibit no rotation and should finish with the buccal cusps lined up with the pre-molars and the second molars. Pre-molar and molar torque
Finishing off with full thickness archwires should express the predetermined torque as designated by the prescription brackets and appliance of your choice. Failure to achieve
the correct torque may be the result of incor- rect bracket placement, anatomical variation in crown shape, or failure to match archwire size with bracket slot size.
These elastics are more effective if the arch- wire is sectioned between adjacent teeth that need vertical movement. As an alternative to sectioning the archwire, replace it with a dead-soft arch made by twisting two strands of 0.254 mm (0.010 inch) dead-soft stainless steel ligature wire as described by Binder and Scott.3Pay careful attention to the direc-
tion of pull or force vectors of the vertical elastics. If, for example, you require vertical eruption of a maxillary canine, then use tri- angular elastic from the maxillary canine to the mandibular canine and first pre-molar; if you require some slight Class II correction as well as vertical eruption, then use angulated vertical elastic from the maxillary canine to the mandibular first pre-molar.
The use of ‘W’-elastic as described originally by Wick Alexander is very useful and effective in improving overall inter-cuspation.4 As an
example, in a Class II division 1 extraction case, using a large 1.88 cm (0.75 inch) elastic, start by hooking it on to the buccal hook of the first maxillary molar then taking both strands of the elastic hook it in a zig-zag fashion down to the mandibular molar, up to the maxillary pre-molar down to the mandibular pre-molar and finish up at the maxillary canine. Either the maxillary or the mandibular or even both main archwires need to be sectioned distal to the canine teeth. In a Class II malocclusion, the elastics finish off at the maxillary canines with a Class II directional pull. In a Class III case, the elastic should finish off at the mandibular canine with a Class III directional pull.
FUNCTIONAL EVALUATION
Prior to the removal of appliances it is essen- tial to evaluate the occlusion in function. Check the occlusion in lateral excursions and forward excursion. Look for cuspal interfer- ences; generally the main culprits are the palatal cusps of the maxillary second molars hanging down too low below the level of the buccal cusps. This interference may be elimi- nated by:
• Judicious occlusal grinding of the offending cusps.
Pearl: Carefully examine the bucco-lingual
inclination of the teeth, particularly the palatal cusps of the maxillary molars; they tend to ‘hang down’ if there is inadequate buccal root torque. Check for excessive buc- cal root torque of the lower molars, the lin- gual cusps may be positioned too far below the level of the buccal cusps.
To correct errors in torque:
• Place adjusting torque in the main arch- wire.
• Reposition the bracket or buccal tube. • If the brackets have vertical slots, an indi-
vidual tooth-torquing auxiliary may be placed on any premolar or molar tooth (Chapter 9).
Marginal ridge heights
It is good practice to check that the marginal ridge heights of adjacent teeth are correct and match up with each other. Inadequate match- ing of marginal ridge heights will result in poor intercuspation and poor occlusion. Extrusion of one or more teeth above the occlusal level of adjacent teeth may lead to cuspal interference. Marginal ridge discrepan- cies are a result of incorrect bracket heights. The most common site for bracket height errors to occur is in the region of the second pre-molars and is due to either incomplete tooth eruption at the time of bonding or due to poor access or visibility in the presence of hypertonic buccal musculature interfering with accurate bracket placement. Marginal height levels can be corrected by:
• Repositioning the bracket.
• Placing compensating vertical offset bends in the main archwire.
• Using vertical intra-oral elastics either from