I. The first picture illustrates the most basic mirror view. The mirror is directly in front of you, and its like looking into a bathroom mirror. Move the bur left, the image goes left. Move it right, the image goes right. But move it forward, the image comes closer towards you. Were all very familiar with this viewpoint, because we use it every day in the bathroom.
II. There are numerous angles that we can place the mirror while in the mouth, but for ease of learning, just choose an angle and go with it. Each mirror angulation changes how we think slightly, and its hard to learn everything at once. At first, we may choose one most common angulation to learn from. Then, we start to change that angulation. I think I may use 30 degrees most often, but I dont remember.
Anyway, when the mirror is angled, all the sudden theres difficulty moving in the right direction. Moving the bur forward has the bur moving at a different angle in the mirror image. Because of that, I reorient my thinking in the angled mirror
III. Practice this using a mirror of your own to see this. Reorient your frame of reference such that youre thinking in terms of the mirror surface plane. When you move it left of the plane, the image goes left of the plane. When you move it right of the plane, the image goes right of the plane. When you move TOWARDS the mirror, the image comes nearer the mirror plane. When you move AWAY FROM the mirror, the image goes farther. Essentially, your new reference is left/right/towards the mirror/away from the mirror.
This has at least one practical meaning. When youre looking at the tooth in the mirror and are confused about which direction to move the bur, you can reorient yourself. For a moment, stop looking at the image in the mirror and look at the rims of the mirror or anything else necessary. Find the mirror plane, so you can readjust your thinking to left/right/towards/away.
IV. When I was first learning how to use the mirror, I drew a figure with multiple arrows coming out, facing all directions. I placed the tip of the bur/pencil at the center of the figure, chose an arrow to push against, then tried to trace that particular arrow (and not another). Its my means of learning to move the bur in the right general direction.
V. Then, when I understood the general direction to move the bur, then its about moving with precision along the right direction. An error of 3 degrees is still too much for dentistry. I started tracing pictures in a magazine.
Simplifying life: Learning in the mirrors hard, but weve all had a lifetimes practice using the mirror while it is at one position: directly ahead of you, as in the bathroom image. No one really has a problem working with things in the bathroom mirror, so the easiest position to place the mouth mirror is directly ahead of you. Youll eventually need to learn to do things with the mirror angled, but in the process, I use the unangled mirror most often. So
readjust the typodont/patient in such a way that you can place the mirror in the unangled position, and maxillary teeth wont pose such a problem anymore.