What type of action characterizes a fixed orthodontic appliance?

What type of action characterizes a fixed orthodontic appliance?

• A. functional
• B. intermittent
• C. mechanical
• D. passive

Answer: (C)

The key idea is that fixed orthodontic appliances move teeth through mechanical forces. When brackets are bonded to teeth and an archwire is seated in the brackets, the wire’s stiffness and shape drive forces and moments on each tooth as it tries to return to its preformed form. This creates continuous, controlled mechanical movement of the teeth, rather than relying on muscle function, growth, or intermittent activation. Functional appliances work by altering muscle activity and jaw function, not by the direct mechanical force of a bonded wire. Passive systems exert little to no active force. So the action of fixed appliances is best described as mechanical.

The key idea is that fixed orthodontic appliances move teeth through mechanical forces. When brackets are bonded to teeth and an archwire is seated in the brackets, the wire’s stiffness and shape drive forces and moments on each tooth as it tries to return to its preformed form. This creates continuous, controlled mechanical movement of the teeth, rather than relying on muscle function, growth, or intermittent activation. Functional appliances work by altering muscle activity and jaw function, not by the direct mechanical force of a bonded wire. Passive systems exert little to no active force. So the action of fixed appliances is best described as mechanical.