Extraction of the first molars and skeletal open bite
Can the extraction of first molars or second premolars make it possible to avoid a surgery in the case where a skeletal open bite is present?
Posterior vertical excess and anterior open bite
Your question is short, but the answer is complex.
First, let’s define the term skeletal open bite. I assume that you want to designate an anterior open bite where the upper teeth do not cover the lower teeth. The above picture presents 2 cases of anterior dental open bite, but with different skeletal problems. The MJBE patient on the left suffers from a dental open bite and vertical maxillary excess, whereas the PABI patient on the right suffers from an anterior dental open bite, without vertical maxillary excess.
Extraction of the second premolars
The MJBE patient on the left underwent the extraction of the upper and lower second premolars to reduce dental prominence and fix the problem of not having enough space.
The above pictures show the result of the orthodontic preparation with the extraction of MJBE’s second premolars. Although the occlusion is excellent, the patient wanted to correct the vertical maxillary excess that persisted. Thus, she underwent a bimaxillary orthognathic surgery and genioplasty. The picture on the right shows the case 2 years after the fixed appliances were removed. We can conclude that the extraction of premolars and the retraction of the anterior teeth can help close an anterior open bite, but will not change the skeletal vertical dimension.
The PABI patient, not having undergone extraction and not suffering from vertical maxillary excess, had to undergo an orthognathic surgery to lengthen the premaxilla in addition to Le Fort I maxillary advancement to correct the Class III relationship.
Extraction of the first molars
With the previous examples, we saw that it is possible to close an anterior open bite, without necessarily changing the skeletal vertical relationship. The reason is that if premolars are extracted, the skeletal vertical dimension is maintained by the occlusion of the first and second molars.
If we want to reduce the skeletal vertical dimension, we have to proceed with the extraction of the first molars when they are the only ones supporting the vertical dimension. This means right before the second molars erupt and before the premolars touch.
In my career, I proceeded with the extraction of the four first molars in only 4 patients. One might say that it is not a lot, but it gives a good idea of what needs to be done and when it needs to be done to succeed. Each of these cases is well documented. I present only one to you; the one illustrated above.
On the left, I indicated the first molars that need to be extracted. Notice that they are the only teeth to touch. The second molars and the premolars have not finished erupting and have not reached the occlusal plane. The anterior open bite is indicated by the red arrow.
The picture in the middle, taken one month after the extraction of the first molars, shows that the second molars support the vertical dimension and the upper anterior teeth cover the lower teeth vertically (positive overbite). The vertical dimension has closed by about 4 mm. The blue Xs show the site of the extracted first molars.
The picture on the right shows the finished case and an optimal Class I occlusion. I would like to specify that the maxilla no longer showed skeletal vertical excess due to the extraction of the upper first molars. However, a small vertical excess was present where the symphysis is. A genioplasty to shorten the chin vertically and to advance it was performed.
The extraction of premolars may reduce, even close an anterior dental open bite, but will have a small or no effect at all on the skeletal vertical relationship.
The extraction of the first molars will have an effect on the closing of the open bite only if they are the only teeth to touch. In adults, this will most likely have a small vertical effect if any at all. In the young patient, it is possible to reduce the skeletal vertical dimension if the extraction is performed before the second molars and the premolars are in occlusion.
Nowadays, with the technique that uses anchoring miniscrews, it is possible to intrude the posterior teeth and close an anterior open bite while reducing the skeletal vertical dimension.
The example above shows a case with 2 tomas®-pin EP miniscrews in the palate and a tomas®-pin EP miniscrew between the first and second left and right molars. The posterior teeth are intruded (the upper and lower teeth go into the bone respectively), which allows the closing of the anterior open bite.
Here is another case using a combination of tomas®-pin and Vector TAS miniscrews.