What is your preference regarding skeletal anchorage as auxiliary to mechanics? Plates or screws? Direct or indirect anchorage?
I routinely use TADs placed between the roots, applying both direct and indirect anchorage. Less frequently in the palate or in the buccal shelf. I have used plates a few times when I did not have other options. Screws placed between the roots easily allow an indirect use by connecting a small rigid wire between the TAD head and one tooth of the anchorage dental unit.
But many times, you can find a way to apply them along the line of action of the force needed to move the active unit. In this way, I can easily build a “perfect” appliance. It is important to place the TAD along this line so that we can apply to the screw a force without applying a moment, since we know that the moment might cause loss of stability in the anchorage screws if they are not osseointegrated and if the moment is acting in a plane perpendicular to the screw axis. You can also use our DMA software to draw the line of action of the needed force and see where it may be convenient to place the screw.
In the example , you can see the line of action of the needed force to displace the incisor from ‘a’ to ‘b’. A TAD can be placed between the roots of the canine and the first premolar, where a cantilever with configuration can be attached. A lot of these examples can be found in Prof. Melsen book about skeletal anchorage.
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