Concept and Commentary: The Extraction-Nonextraction Decision

When I decide between extraction and nonextraction, I consider, primarily, the degree of crowding and the relationship of the denture to the face. For the relationship of the denture to the face, I rely heavily upon the relationship of the anterior teeth to the NP line; and to the AP line as far as determining the degree of convexity or concavity. The question is whether the amount of crowding can be corrected while still maintaining a favorable relationship to NP.

Another factor is the FMA. In a low angle case, with an FMA below 16°, I am leary of extracting in both arches, unless there is a severe amount of crowding. In addition, clinical intuition plays a part. I may swing back and forth on borderline cases. Treatment mechanics also plays a part. I like to think of the difference between a Class I and a Class II as the mesiodistal width of a bicuspid divided between the two arches. If you move the lower arch anteriorly one-half of a bicuspid width and move the upper arch distally to the same extent, each of which is about three or four millimeters, you have changed a Class II to a Class I. If this is feasible considering crowding and facial fullness, the case can be treated nonextraction.

In addition to all these, the inclination of the upper molars may be a factor. Quite often, mesially inclined upper molars can be corrected to a Class I much more readily than those which are upright or distally inclined. The anchor bends in the Begg technique are intended to upright a mesially inclined molar; but not to tip an upright molar distally. If it does that, there has been too much anchor bend and the mechanics are wrong.

Here is a case that demonstrates some of these points.

[show_img]621-jco-img-0.jpg[/show_img]It was a Class II with mesially inclined upper molars. There was very little crowding in the lower arch; almost 10mm of protrusion, with spacing, in the upper arch. The labial surface of lower incisor was on the NP line and there was a well-developed pogonion. FMA was a relatively low 27°.

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So, this case had a number of factors that marked it as a nonextraction case in my book.

My first objective was to open the bite and to upright the mesially inclined upper molars. I put in some strong anchor bends on the molars and used very light Class II elastics.

[show_img]621-jco-img-3.jpg[/show_img]Most of the time, on nonextraction cases, I do not band bicuspids. I usually just band the molars and the six upper and lower anteriors. Occasionally, I may need bicuspid bands later in treatment.

I got the bite opened and the molars went from a Class II to a Class I in four months. His entire active treatment took less than sixteen months. I did not use an upper retainer on this case. On the lower, I used a 3-3.

[show_img]621-jco-img-4.jpg[/show_img]I don't really think that if you have an FMIA under 65° that you have ruined the face.

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This patient had a pretty good face with an FMIA of 55°. I think it is the position of the incisal edge relative to the NP and AP lines that is important: Here the lower incisor was right on the NP line and less than 2mm in front of AP line.

His upper right central and lateral teeth had been injured prior to treatment and I did a lot of grinding on those teeth to eliminate the fractures.

Here is another nonextraction case.

[show_img]621-jco-img-7.jpg[/show_img]It was a Class I with a six to eight millimeter overjet at the incisal level. There was not as favorable a relationship of lower incisor to NP and AP. However, there was no crowding in the lower arch and the FMA was 23°.

[show_img]621-jco-img-8.jpg[/show_img]There were enough favorable factors in this case to throw the balance to nonextraction. Once again, I banded just the six upper and lower anterior teeth and the four first molars. I placed strong anchor bends in the archwires and used very

light Class II elastics.

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This boy had practically no retention on his upper teeth. As a rule, I tend to minimize upper retention on nonextraction cases. I play them by eye. I may let them go for six weeks and, if it is obvious that spaces are getting larger or I am losing some vertical, then I will put in an upper Hawley with a bite platform. In this case, I may have used an upper Hawley with a labial elastic for the first couple of months. On the lower, I used a 3-3.

[show_img]621-jco-img-10.jpg[/show_img]He wore a rubber band from cuspid bracket to cuspid bracket for about six months to gather the lower incisors and to upright them a bit. I use a rubber band in this way on most cases. Its position is dictated by need. For example, when appliances are removed, the lower incisor edges may be a little flared. In that case, the lingual bar of the 3-3 is placed low and the rubber band on the labial is placed a couple of millimeters above that. This gives a little torquing action and you can improve that axial inclination a little.

When I am through with the labial elastic action, I grind the brackets off the cuspid bands and continue the 3-3 retainer.

We got some good growth in this case and a good face.

[show_img]621-jco-img-11.jpg[/show_img]The FMIA was 63° in this case and the relationship of incisal edge to NP and AP improved a bit. We started out with a good chin and that grew a bit more.

Incidentally, notice that the contact of the upper centrals initially was high up at the gingival. I am more and more uprighting roots distally on centrals such as this, using uprighting springs to move the contact farther incisally as I did here. Also, I do a fair amount of contouring as on the cuspids here. Just artistic shaping of the teeth.

This next case is a Class II division 2, with the upper incisors biting the lower gingiva.

[show_img]621-jco-img-12.jpg[/show_img]With such a big pogonion, with lower incisor so far behind the NP line, with such a low FMA, this is definitely a nonextraction case.

[show_img]621-jco-img-13.jpg[/show_img]As for most of these people, I banded the upper and lower molars and the six upper anterior teeth only, because the bite would chew up the lower anterior brackets.

[show_img]621-jco-img-14.jpg[/show_img]I did not place lower anterior bands. Instead, I had a lower lingual arch. I put severe anchor bends in the upper archwire and used 3-4 ounce Class II elastics. The object is to get the anterior teeth away from each other. If I can get the upper anteriors labially, I can then place the lower anterior bands behind them. I used the vertical loops to assist engagement and to obtain action on all the teeth at once.

Usually, I make it a point to avoid loops in nonextraction cases where there is a severe amount of crowding, because the cuspids cannot go distally and you are liable to displace an incisor through the labial plate, especially in the lower arch. Under those circumstances one might consider one lower anterior extraction.

If I have just one rotated lateral, I would make a plain arch with no vertical loops, but oversized with the elastic loops up against the cuspid brackets. I may tie the lateral with ligature a couple of times before engagement with a pin. It is a matter of time and expediency. It is not that critical that you get that tooth rotated perfectly before you start your retraction. It doesn't affect your overall treatment if that tooth is not completely rotated in the first two or three months. You can go ahead and open the bite and start retracting, and you can be rotating all during this time. If three or four of the six anteriors were rotated and one or two badly so, I would start with vertical loops in the archwire.

Appliances were removed after 23 months of treatment.

[show_img]621-jco-img-15.jpg[/show_img]This boy started out with an upper Hawley, which he lost almost immediately, and a lower 3-3 with an elastic from cuspid bracket to cuspid bracket to upright the incisors. When patients lose the upper retainer, I often leave it out for a while to see what will happen. I did in this case and never did replace it.

[show_img]621-jco-img-16.jpg[/show_img]The post-treatment photo and ceph show improvement in the face with a good amount of vertical growth and an increased chin growth.

Here is a textbook Class II division 2 with the laterals out, centrals in, and upper bicuspids tending to crossbite.

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With an FMA of 24°, with lower incisor behind the NP line, and especially with lower incisor so far behind the AP line, I felt that extraction would not be conducive to facial improvement. If I ever extract in the lower arch in division 2's, I start out using heavy Class II forces and burning anchorage. The object of lower extraction would be to permit alignment of the lower teeth. Although the lower teeth were irregular in this case, the amount was not sufficient to counterbalance the factors which favor nonextraction. The amount was sufficient, however, to permit banding of the lower anterior teeth from the start of treatment in this case.

[show_img]621-jco-img-19.jpg[/show_img]Once again, the purpose of the vertical loops is to secure engagement and to get the action going on all the teeth at once, but I get out of loops as quickly as possible. Here we are about one year into treatment.

[show_img]621-jco-img-20.jpg[/show_img]Notice the offset bends in front of the molar tubes to clear the bite, and notice that I do not repeat them anteriorly. The little offset in the lower anterior region was to adjust for the height of one incisor which was fractured. Notice, also, that I am getting a little tipping. With a lot of Class II forces in a nonextraction case with this setup, the molars tend to tip, with the apices beginning to come anteriorly and the crowns to roll distolingually. Now, on this type of case or on any case with a deep bite, where I know I'm going to

have a lot of strain on the molars, I will use a lower lingual arch. In any event, on all nonextraction cases, I put lingual tubes on the molars rather than lingual buttons, with the idea that they are there if I have to go to a lingual arch. Well, we got some lingual tipping in this case in spite of the fact that I had a lower lingual arch in place with a tab extending back onto the lingual of the second molar to help control.

Here is the case two years later and, once again, upper retention was for a very short period of time, because the patient lost his retainer within three months. The usual lower 3-3 retainer was used.

[show_img]621-jco-img-21.jpg[/show_img]The lower left first bicuspid wanted to come buccally, and I think perhaps I should have used a lower 4-4 retainer instead of the 3-3. In cases in which you have brought the lower anterior teeth forward due to facial requirements, I think they tend to go distally at the expense of displacing a bicuspid either to the buccal or the lingual.

We got a phenomenal amount of growth in this case.

[show_img]621-jco-img-22.jpg[/show_img]This is another example that FMIA cannot be the ruling criterion in cases like this. FMIA was 71° before treatment and 53° after treatment. The criterion of this satisfactory facial result is the relationship to the NP and AP line, plus the good torquing action on the upper incisors.

We have looked at four nonextraction cases-- a Class I, a Class II division 1, and two Class II division 2's. Now, let's compare nonextraction and its criteria with a typical four-bicuspid extraction case in my practice.

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This was a high angle case with an FMA of 38°. There was crowding of the lower anterior teeth which were already well forward of the AP line and twice as far forward of the NP line. Chin development was poor and the face was protrusive.

[show_img]621-jco-img-25.jpg[/show_img]We went through a typical treatment, and here is the case in early retention .

[show_img]621-jco-img-26.jpg[/show_img]Notice that the lower molar is cocked a little bit. I think that if you start grinding on something like that, it is wrong. This will settle in real well. I used a wire retainer on the upper teeth in this case, because the lateral had been too rotated to retain with an elastic.

About one year later, see how those molars have settled in.

[show_img]621-jco-img-27.jpg[/show_img]And, here is the case one year later, in post-retention.

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The face is improved. There has been a good deal of forward growth of the mandible, but not much chin development. The relationship to NP and AP lines is improved. One additional reason for showing this case is that some people tend to knock the Begg technique on mandibular rotation and angle opening. Well, I think that the angle FMA actually closed two or three degrees during treatment.