The subject of wire-bracket angles is the basis for the application of force systems in orthodontics.

Force systems will be formed as a result of the wire-bracket angles created when the archwire is inserted into the bracket slots.

Different wire-bracket angles will produce a different force system.

After the introduction of the straight wire technique in orthodontics one term has become significant - it was defined as Deviation Angle or Wire Play (or Clearance).

It is a rotation movement (angular rotation) of the rectangular arch wire from its passive position (transverse *cross* section of arch wire parallel to the bracket slot walls) to a position where two opposite edges (diagonal corners) of the arch wire contact two opposite walls of the bracket slot.

This app allows you to calculate the amount of play (the critical contact angle) for any arch wire-bracket slot (size) combination.