Types of Intrusion
- True Intrusion: Incisors move towards the bone without movement of posterior teeth
- Relative Intrusion: Extrusion of posterior teeth to correct deep bite
- Can be performed in adolescents with deep bite tendency

Methods of Intrusion
- Burstone's Intrusion Arch: Segmental arch method with low magnitude forces
- Ricketts Utility intrusion arch: Continuous wire with statistically indeterminate system
- Three-Piece intrusion arch: Developed for retraction and intrusion simultaneously

Types of Cases for Intrusion
- Deep bite with vertical facial growth pattern: Manage vertical growth and prevent eruption of posterior molars
- Deep bite with horizontal facial growth pattern: Increase vertical height through relative intrusion

Major Principles of Intrusion
- Controlling force magnitude and consistency
- Single point contacts on anterior teeth
- Point of force application and center of resistance
- Selective intrusion based on anterior tooth geometry
- Control over reactive units and avoidance of extrusive mechanics

Force Magnitude in Intrusion
- Force magnitude must be constant throughout application
- Higher force can lead to side effects such as root resorption and extrusion of posterior teeth
- Equal and opposite forces are produced at incisors and molars
- Use wire with low load-deflection rate for constant force of intrusion