Cartas al director

The intermediate surgical splint in bimaxillary surgery.
A simple method for obtaining it

Férula quirúrgica intermedia en cirugía ortognática bimaxilar:
Un método simple de obtención.

Dear Sir,

I would first like to thank you and the rest of the Editorial Committee of the "Revista Española de Cirugía Oral y Maxilofacial", on behalf of the authors, for your courteous regard on publishing the work "The Intermediate Surgical Splint in Bimaxillary Surgery. A simple method for obtaining it."

With regard to the "Discussion" that accompanies the article, and given the opportunity in the Publication Guidelines that is offered to the authors to respond, we would like to give you our point of view, in the hope that it is considered suitable for publishing.

We appreciate the interest shown by the author in the discussion, which is the fruit of his undoubted prestige. We agree with him on the fundamental aspects that he gives as an introduction. Nevertheless, we are attributed errors that we feel we should reject.

We are told that we try to simplify the repositioning movement of the maxillary model using as a reference the mandible instead of the Frankfort plane, and that we state that the position of the mandible is invariable during the simulation process. It is then added that we are mistaken.

We do not agree with this. In any semi-adjustable articulator, the upper arm provides the mandibular movement. In the classical procedure used for obtaining the splint it would not be correct to vary the vertical dimension (as the posterior hinge axis is not reliable) and, in addition, condylar movements are not carried out because they are not needed. Only the cutting handsaw* is used on the upper platform. We should therefore recognize that the mandible remains immobile in relation with the skull base (Frankfort plane or upper arm of the articulator) and everything that surrounds it.

It is not without reason that we reiterate that the preoperative vertical craniomandibular dimension should be the same as the postoperative craniomandibular dimension with the splint in place. This is an essential concept.

Further on in the discussion it is stated that "If there is anything of importance in the planning of maxillomandibular movements, it is the position of the maxilla..." and that "reaching the objective would be difficult if in the planning the face and maxillomandibular complex have not been related.

We are of course in total agreement. The planning of the surgery is based exclusively on the maxilla being in the optimal position with regard to the rest of the skull and face. This position will be obtained in the cephalometric (point A, occlusal plane) and in the clinical (forehead and profile, midline, lip line, smile lines, etc.) as well as from the intrinsic characteristics of the upper occlusal plane. This is such a basic concept, and our agreement with it is such, that we could even affirm (though it might appear strange to read this) that in order to obtain the conclusions that we are looking for, dental skull lateral teleradiography would be useful even if "the mandibular bone were not to appear in it."

The changes required in the maxilla should be obtained correctly and the mandible can later be corrected in order to obtain the final occlusion.

With our positioning device we are not studying the case. The case has "already" been studied; we know how much and in what way the maxilla has to be moved.; the only thing that we have to do is: perform this. We do not question the diagnosis, the application, or the procedure. We only guarantee the result. That is to say, we make the splint.

The semi-adjustable articulator has been conceived so that small corrections in the vertical dimension can be carried out together with condylar protrusive, working and balancing movements. The models are mounted with a space relationship between the facial arch and the condyles and Frankfort plane. If one should not change the vertical dimension or the condylar movements with the classical method for obtaining a splint: why do we need an articulator? For the Frankfort plane reference, perhaps? Will this plane influence the way the surgical cut is made, or would it be more correct to say that the surgical cut/plane should be the one dictated by the chisel as it crosses the floor of the nasal pit?

If this is the case, we should mount the occlusal plane of the maxillary model at an angle that is in relation with the anterior nasal spine- posterior nasal spine (palatine plane) and we should move the Le fort fragment that we will obtain in the operating room, according to the previously obtained parameters.

A splint obtained in this way will obviously be more reliable than if it is obtained by means of sawing along a line that had been traced parallel to the Frankfort plane on the platform of the maxillary model, which will hardly coincide with the angle at which the bone is cut.

In short, we feel that the "Discussion" we are replying to is based on concepts that are completely correct, but that these do not modify the arguments on which the maxillary positioning device is based. Both philosophies are correct and do not exclude each other; they simply reach the objectives set out through different procedures and, in our case, we obtain a much more reliable by using a method that is extraordinarily simple.

José V. Pascual Gil