A TREATMENT METHOD FOR CLASS II DIVISION 1

PATIENTS WITH EXTRACTION OF PERMANENT MAXILLARY MOLARS

Hans Booij

Through the years a great variety of options for the treatment of Class II malocclusions have

been presented, there are orthopedic, func-tional, nonextraction and extraction proce-dures. Of course as an orthodontist, your preference of choice depends on the character, the severity of the malocclusion, your back-ground, and your training. Recent alternatives offered in the literature are miniscrew implants and sub-mucosal bone anchored miniplates (see Chapter 17). No doubt evidence-based studies will continue to produce opinions on the optimal treatment solutions for the indi-vidual patient.

Clearly it is outside the scope of this presen-tation to discuss the diagnosis and treatment planning aspect of Class II malocclusions. It is assumed that the case requires Class II correc-tion and that one of the opcorrec-tions would be the extraction of maxillary first molars.

The views presented in this presentation are based on my philosophy related to achieving tooth movement which to a large part is inde-pendent of patient cooperation and reduced concern with anchorage preservation by means of extraoral support or skeletal anchorage. For this form of treatment, low friction brackets and long molar tubes are a prerequisite.

Low orthodontic forces will do the job. So

‘Mother Nature’ is helping the orthodontist and of course this benefits the patient. As a prerequisite, the anatomy of the second molars must be acceptable and the upper wisdom teeth, the so called ‘hidden molars’, have to be present. In adolescents, these third molars will erupt earlier after extraction of the upper first molars, as described by Livas.¹³

Pearl: The ability to add spacers selectively and unilaterally is a significant benefit as many Class II malocclusions present with slight asymmetries.

Pearl: This approach involves extraction of upper first molars to facilitate the rearrange-ment of the dentition and the occlusion incor-porating the natural tendency for mesial drift of the upper second molars and distal drift of the upper premolars.

Pearl: With the upper wisdom teeth in occlu-sion, the finished case looks like a nonextrac-tion case showing an ‘eight premolar smile’

generally even more attractive than after pre-molar extraction.

At the start of treatment the second upper molars must be erupted; they have to be banded.

14.3.1 Treatment Protocol

Class II correction after upper first molar extrac-tion is a so called ‘low compliance treatment’.

In most cases the boy or girl needs to change the horizontal elastics in the upper arch only once a week. After a short while the patient will see a decrease of the extraction space and a decrease of the overjet and overbite, this encourages, motivates and optimizes the treat-ment progress (Figures 14.10 through 14.12).

In case of a deep overbite, treatment is started with a bite plate in the upper jaw and fixed appliance in the lower. If necessary mild tooth stripping of the lower arch can be done gener-ally between the lower canine and first premolar.

The initial archwire is a 0.36 mm (0.014 inch) Light Lower Accuform Medium Sentalloy (Dentsply). After about two months the second and last lower arch is placed. This is a

custom-made 0.46 mm (0.018 inch) Australian special plus archwire (G&H Wire Company;

Franklin, IN, USA). Minor corrections may be necessary with the placement of (small) hori-zontal and vertical offsets. Using the initial plas-ter models, the original arch form and dimensions are maintained as far as possible.

Anchor bends mesial of the first molars and v-bends between the premolars and between the canines and first premolars will open the bite. The combination of the upper bite plate and fixed appliance in the lower arch will result in intrusion of the lower incisors and some extrusion in the lower buccal regions. The verti-cal position of the upper front teeth remains unchanged and often this is desirable.

In most cases the upper first molar extrac-tions can be carried out after five months. Two to three weeks after the extractions, the bite plate is abandoned, the upper second molars are banded and the upper front teeth are bonded (Figure 14.13).

Upper premolars are only bonded after achieving a Class I premolar relation in order to minimize binding during the Class II correc-tion phase. To make the treatment procedure clearer, we have divided it in three phases: the

Figure 14.10

(a) Pretreatment full face. (b) Pretreatment profile.

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already mentioned Class II correction phase, the space closure and torque phase, and the detailing and finishing phase.¹⁴

Second molar control is enhanced by the use of a palatal bar and anchor bends placed

±5 mm mesial of the molar tubes.

In total only two maxillary archwires are required, the first is custom made 0.41 mm (0.016 inch) premium plus pull straightened Australian wire (G&H Wire Company). Circles bent into the archwire mesial of the canine

brackets prevent the arch from excessive slid-ing. High hat lock pins (TP Orthodontics, Inc.) are placed in the upper canines with the gingi-val oriented hook bend to the mesial to host the light 8 mm (5/16 inch) horizontal elastics to the buccal ball end hooks on the second molars.

The patient and the parents are instructed to replace the elastics once a week. It is important to instruct the patient not to use the circles to attach the elastics; only the canines must move/

slide along the arch. In cases where the incisors

Figure 14.11

Pretreatment occlusion. (a) Right; (b) centre; (c) left.

Figure 14.12

Start of active treatment with a lower fixed appliance and upper removable incorporating an anterior bite plane. (a) Right view; (b) front view; (c) left view.

are malaligned, I use a sectional 0.41 mm (0.016 inch) Co-Ax wire canine to canine. (For exam-ple, see Figure 14.14a.) The incisors are tied to the main arch with steel ligatures. In this way the anchor bends in the main archwire can

maintain good vertical control while the ante-rior teeth are being aligned and the elastics are active on the canines (Figure 14.14).

To accelerate the Class II correction the use of medium 8 mm (5/16 inch) Class II elastics can

Figure 14.13

Following extraction of maxillary first molars, fixed appli-ances fitted to the maxillary teeth excluding the premo-lars. Intraoral elastics from maxillary molars to the canines. (a) Right view; (b) front view; (c) left view.

Figure 14.14

Brackets bonded to the maxillary premolars. Note the movement of the canines and premolars into a Class I rela-tionship. Reduced overbite. Sectional Co-Ax wire to align the UR2. (a) Right view; (b) front view; (c) left view.

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be considered; in that case the patient is instructed to replace them every day. The Class II elastics are also placed from lower molar to the high hat pins on the canines. In case of an asymmetry the unilateral use of Class II elastic could be the solution. The patients are seen at seven to eight week intervals.

At the control visits the distal ends of the upper archwire have to be adjusted and the orthodontist has to analyse the treatment progress in a precise way. For example, partial grinding of the lower premolar brackets may be necessary to avoid occlusal interference and to facilitate distal drift of the upper premolars.

It is fun to see the development of spontaneous spaces between the upper premolars; these teeth really want to move to the distal.

Generally after five months, a Class I premo-lar occlusion is established. Now time has come to bond the upper premolars and to adjust the upper archwire. Place v-bends and anchor bends to prevent deepening of the bite.

So, look at the initial situation and judge how the teeth have reacted to the orthodontic ther-apy so far. Large individual variations are pos-sible which may require some adjustments. In some cases spacing between the upper front teeth may need to be closed at this time using small elastics from the canine brackets to the circles in the archwire. The use of Class II elas-tics can be restricted to night use only or even be stopped.

The next visit can be scheduled in four weeks. Are the spaces between the upper front teeth closed? Yes, then the second phase, space closure and torque, is started (Figure 14.15).

This is the second archwire. A custom-made 0.46 mm (0.018 inch) Australian special plus archwire is placed in combination with a 0.36 mm (0.014 inch) Australian regular wire two spur torque auxiliary and power chain in the buccal segments for closure of the remain-ing extraction spaces. Is this a straight arch-wire? No, again, as necessary small horizontal and vertical steps are bent in this second and last main arch. At this stage, the orthodontist really has to concentrate on all the details in the mouth. If indicated, uprighting springs (TP Orthodontics, Inc.), can be placed on the upper canines. Based on the orthodontist’s evaluation of the anchorage situation, the pal-atal bar can be removed, to facilitate the mesial

Figure 14.15

Note 0.46 mm (0.018 inch) Australian special plus arch-wire is placed in combination with a 0.36 mm (0.014 inch) Australian regular wire two spur torque auxiliary and power chain in the buccal segments for closure of the remaining extraction spaces. (a) Right view; (b) front view; (c) left view.

movement of the second molars. Again the orthodontist has to judge the necessity or oth-erwise for Class II elastics.

The seven to eight week intervals are back again. At these visits, the power chains are renewed and if an extraction space is totally closed, the distal end of the arch is tightly bend distal of the second molar tube. The beauty of this phase is the balance of torque forces and lateral space closure but, of course large individual differences can occur. In the last phase, the finishing phase, adjustments are made in the arch wires and if necessary the palatal bar can be adjusted to correct molar root torque. Check the degree of ante-rior root torque; the best way to do it is to request the patient to stand up and show the teeth, I favour the procedure and criteria for examining anterior aesthetics as described by Zachrisson (Figure 14.16).¹⁵

My method of choice for retention is the placement of bonded custom made retention wires from canine to canine in both arches. To prevent the over eruption of lower second molars check the contact between the distal ridge of the upper second molar and the mesial ridge of the lower second molar; if there is no contact, bond a piece of retention wire on the buccal surface of the lower first and second molars. This is removed after the generally early eruption of the upper wisdom teeth (Figure 14.17).

I am aware that there are many appliance sys-tems (generally more expensive) that have been designed to simplify clinical treatment but in cases where first maxillary molar extrac-tions are an option, the system I have described is capable of delivering excellent results.

However, if the clinician wishes to translate

this concept to other bracket systems, they need to ensure the use of minimal friction brackets and as an adjunct I would recommend using a Begg bracket (TP Orthodontics, Inc.;

256-Begg bracket bicuspid) for the upper canines. This makes use of optimal sliding effects and prevents vertical complications.

After uprighting of the canine at the end of the Pearl: I want to stress the simplicity of the

materials needed for this treatment concept.

Just two arches in both jaws, the brackets are simple and inexpensive and some bands and a palatal bar complete the instrumenta-tion. I believe this treatment protocol could be of great help in areas of the orthodontic world where material costs are a factor, but orthodontic knowledge and manual skills are present.

Figure 14.16

Final occlusion, note the Class I occlusion of the maxillary second molar with the mandibular first molar and the reduced overbite. (a) Right view; (b) front view; (c) left view.

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second phase, the bracket can be replaced by another bracket of personal choice.

This form of appliance therapy was first described by Williams in 1979¹⁶ and fine-tuned by this author.¹⁴ Stalpers et al.¹⁷ reported a 90%

improvement of the peer assessment rating index in a group of 100 Class II division 1 patients, thus demonstrating the efficacy of this approach. A number of studies have eval-uated the cephalometric and clinical results obtained with first molar extraction cases Figure 14.18 and 14.19.^18,19

14.4 LATERAL MOLAR EXPANSION