THE EDITOR'S CORNER
Orthodontic treatment has lacked a correlation between the mechanics of most techniques and the anatomical environment within which these techniques operate. We tend to have a diagrammatic concept of bone remodeling accompanying tooth movement in a uniform environment without consideration of the difference that density of bone may make, specifically cortical bone.
We have established treatment goals disregarding or without being aware of serious limitations resulting from individual bone anatomy and we have used treatment methods to achieve these goals which were hampered or frustrated by the anatomical limitations.
JCO is presenting a series of three papers by Drs. Ten Hoeve and Mulie (with Dr. Brandt of our staff) which address themselves to movement of the anterior teeth in relation to the cortical bone of the palate and of the symphysis. The maxillary problem is covered in this issue and the symphysis will be covered in the next issue. In a third paper, changes in mechanotherapy to resolve some of the lack of correlation of mechanics to anatomy will be suggested.
Using unique methods, the authors demonstrate new understanding of the anatomy of these areas in relation to what orthodontists are trying to accomplish in them.
Edwards has recently pointed out the need to evaluate the width of the alveolus through which orthodontists set out to move teeth bodily and with torque. Ricketts has recognized and taken advantage of intrusion of anterior teeth in his treatment mechanics. Ten Hoeve and Mulie seem to confirm this and suggest some general thoughts about some standard, conventional approaches to orthodontic correction.
They suggest that indiscriminate leveling of the curve of Spee, disregarding the bony environment of the mandibular incisor teeth, may produce variable relative extrusion of the posterior teeth and intrusion of the anterior teeth, and the relative amounts of each may be more important than most of us have realized to obtain a stable result. After reading the work of Ten Hoeve and Mulie, we cannot indiscriminately apply a step-by-step treatment system to an individual without first having a better understanding of his individual anatomic tooth environment within which we propose to change his tooth positions.
Orthodontists will have to be more discriminating about extraction which is followed by excessive lingualization of upper incisors, and more discriminating about torque. We have been under the impression that all that is required is to place a torquing appliance and wait, monitoring the amount of torque cephalometrically and stopping when we arrive at the desired amount. Up to now, we haven't had a good interpretation of why some took longer, why some didn't fully achieve the desired position, why some relapsed, and why some showed resorption. Now we have, and it may revolutionize our thinking and procedures in these important regards. Gung-ho torque to produce a certain interincisal angle, or an esthetic result, or a certain angle of upper incisor to SN or lower incisor to mandibular plane must be reevaluated.
A significant thought that comes to mind is that disregard for the juxtaposition of anterior tooth roots and palatal cortical plate may cause anchorage to be set up in the anterior and result in arch length loss by mesial movement of the posterior teeth. When this thought is combined with their demonstration of root resorption, with their indictment of excessive lingualization, and with their questioning of excessive tipping as instrumental in extruding upper incisors, we look forward to their third article on suggested changes in mechanotherapy to improve on some of the deficiencies they are alluding to. The movements that they refer to in treatment of Begg cases are common to most other techniques, and the considerations apply equally to any technique that levels indiscriminately, that retracts indiscriminately, and that torques indiscriminately.
It seems to me that we ought to take a closer look, from this point of view, at the philosophy and treatment techniques of Ricketts. They seem to be closer to this understanding of the relationship of tooth position and tooth movement to bony environment than other techniques.
We are also going to have to recognize more often those cases in which the anatomical limitations are too great to overcome with tooth movement alone and for which surgical-orthodontics is necessary. Also, what applies in the anterior region must apply to the remainder of the alveolar trough. This kind of investigation should be extended into the cuspid area and into the posterior segments. For the present, most importantly, we must acknowledge the observations of Ten Hoeve and Mulie and encourage the commercial development of equipment to permit us to make use of their methods to evaluate the position of each of the anterior teeth with relation to cortical bone before we set out to move teeth in its direction.
