By: Dr. Mike Lowry
The purpose of this article is to demonstrate some bends in arch wires that can assist in finishing cases. These bends necessarily need to be made on wires that will hold a bend. The most reliable wires are stainless steel followed by beta titanium. The wire could be round, square or rectangular but the easiest wire to perform a 3-dimensional bends on is round wire. By mastering a few simple bends, it is possible to enhance our finished cases with more predictability. Following will be a few examples of wire bends that will address some common problems with our cases as we near the end of treatment. It is important to remember that these are our final wires since going back to leveling and aligning wires or torquing wires will undo the work accomplished with these bends. Leveling, aligning and torquing should already be completed prior to finishing with bends. Most of the bends needed to complete these movements require a step bend or combination of step bends. I would therefore like to review some principles associated with a successful step bend. My plier of choice is a simple bird beak and I have found the Triumph 205-304 to be a very nice plier for all these applications. The distance of the step will depend on the degree of the bend on either end of the step as illustrated below. The red circle and square represent the tips of the bird beak pliers (Figure 1a-e).
The first application will address rotated teeth. The areas where rotations seem to be most prevalent near the end of treatment are the bicuspids and lower anteriors. By employing the correct step bends in the arch wire, it is possible to derotate these teeth without having to rebracket. This is demonstrated below in Figure 2a-h.
Next, we will look at occluso-gingival height issues. This relates to marginal ridge discrepancies and also “socking in” cuspids. Marginal ridge issues seem to be common between the molars and 2nd biscuspid and also anterior teeth. Using step bends in the wire can correct these issues. This step bend can correct individual teeth or segments of teeth. The following illustrations (Figure 3a-g) will demonstrate this principle.
I would next like to address the problem of improper root tip. As with all the items discussed in this article, the problem is one of bracket placement. It does not seem to matter how experienced the operator or how long one has been doing orthodontics, perfect bracket placement on every case seems to be a goal that we all fall short of. The issue of improper root tip relates to the bracket not lining up with the long axis of the tooth. Note the following illustrations and how the bends accommodate the correction of the root tip issues Figure 4a-d.
These examples are by no means all inclusive. There are many more applications that may be the subject of a future article. There are probably as many applications to the bends as there are patients. It is also possible to achieve the same results by rebracketing teeth. Experience has shown that rebracketing does not ensure proper placement of the bracket on the 2nd (or 3rd + ) attempt and requires more time going through arch wire sequences. The goal of this article is to demonstrate principles that will allow the operator to assess a situation and devise a solution based on principles of wire bending. The result should lead to a nice occlusion in a reasonable amount of time as illustrated in Figure 5.