🌟 DEFINITIONS IN ORTHODONTICS
🔸BINDING: During tooth movement along an archwire, a high couple occurs between bracket and wire, owing to overtipping of the tooth. Binding is the locking of these two materials due to friction. As a result of binding, tooth movement stops. Binding can also occur during sliding of the wire in en masse movements.
🔸BOWING EFFECT: Increase overbite by incisor extrusion after a straight wire is placed in incisor brackets and angulated canine brackets.
🔸BREAKING POINT: The point at which a wire material fails.
🔸CENTER OF ROTATION: The imaginary point around which a tooth rotates. The location of this point changes depending on the force system applied to the tooth (ie, the moment/force ratio).
🔸CORROSION: Loss of weight of metal and change of its mechanical properties under various chemical influences.
🔸COUPLE: A system having two equal and parallel forces acting in opposite directions. Every point on the object to which a couple is applied is under a rotational influence in the same direction and magnitude. The object rotates about its center of resistance regardless of where the couple is applied. For example, torque applied to a bracket makes the tooth rotate around its center of resistance and not around the bracket.
🔸DIFFERENTIAL FORCE (anchorage) PRINCIPLE: Taking advantage of the anchorage differences between two teeth (or groups of teeth) when moving them toward or away from each other.
🔸DYNAMIC (kinetic) FRICTION: Friction that exists during movement of an object; the amount of force the object must overcome to continue moving.
🔸ELASTIC DEFORMATION: The shape deformation of a wire that occurs up to its elastic limit.
🔸ELASTIC MATERIAL: Material that can return all the energy it absorbs, thus regaining its original dimensions when the stress is removed.
🔸FATIGUE: Weakening of a material under repeated stress.
🔸FORCE: The factor that causes an object to change its shape or position in space. Force is a vector having a line of action, direction, magnitude, and point of application.
🔸FORMABILITY: The permanent deformation a wire can sustain before failure.
🔸FREE OBJECT ANALYSIS: Analysis of an isolated part of a force system representing the whole system or an object in static equilibrium. This analysis helps one see the entire perspective of the object or system.
🔸FRICTIONAL FORCE: The resistance at the contact surface in the opposite direction to the movement when two objects in contact are forced to move along each other.
🔸HOOKE’S LAW: According to this law, stress applied to a material up to its elastic limit is directly proportional to the strain.
🔸HYSTERESIS: The difference between the slope formed when a superelastic wire is activated and transforms from the austenitic phase to the martensitic phase and that formed when the force is removed and the wire follows a different path below that of activation, returning to the austenitic structure.
🔸LACEBACK: A ligature tied between the molar tube and canine bracket to prevent the canine crown from moving mesially.
🔸LIMIT OF ELASTICITY: The point beyond which permanent deformation occurs.
🔸MODULUS OF RESILIENCE: The area in a stress-strain diagram between the starting point, elasticity limit, and vertical line from the elasticity limit to the x-axis.
🔸MODULUS OF TOUGHNESS: The area in a stress-strain diagram under the slope brought down to the x-axis from the starting point and the failure point.
🔸MOMENT: The magnitude of force (F) times perpendicular distance (d) drawn from the center of resistance to the line of action of the force, shown as M= F X d.
🔸MOMENT/FORCE RATIO: The ratio of the moment of a couple effective on the tooth and the force applied to the crown.
🔸NORMAL FORCE: The force perpendicular to the surface that causes friction between two objects.
🔸PERMANENT DEFORMATION: The permanent shape deformation of a wire due to excessive stress beyond the elastic limit
🔸PITCH ANGLE: The angle between a line perpendicular to the long axis of a spring and the inclination of the windings of the spring.
🔸PLASTIC MATERIAL: A material that does not return to its original dimensions when stress is removed.
🔸PURE ROTATION: The rotation of an object that occurs because of a couple.