History and Development of the Activator Appliance
- Viggo Andersen first used the appliance on his daughter's teeth in 1908.
- Andersen saw positive results and began using the appliance in his private practice.
- Andersen and Karl Haupl coined the name 'Activator' for the appliance.
- The Activator was first mentioned in their textbook in the 1920s.
- The Norwegian System was the name given to their way of working with the Activator.

Indications and Malocclusions treated with the Activator
- Activator appliance is indicated for growing patients.
- Young adolescents with growth potential show the best results.
- Retrognathic mandible and well-aligned dentition are also indications.
- Malocclusions treated with the Activator include Class II Division I, Class II Division II, Class III, and Open Bites.

Mode of Action and Functional Adaptation
- The initial theory involved Isometric Muscular Contraction caused by Myotatic reflex activity.
- Another view focused on the Viscoelastic Properties of Muscle and stretching of soft tissues.
- Lateral pterygoid muscle was found to play an important role in mandibular condyle cartilage growth.
- Functional adaptation led to a new way of mandibular closing pattern.
- Different proponents had different views on the primary way of functional adaptation.

Components and Construction Bite of the Activator
- Activator consists of acrylic and wire components.
- Acrylic components include a horseshoe-shaped lingual plate and coverage of the anterior portion in the upper arch.
- Wire components include a labial bow placed 1mm away from the incisors and additional elements for stability.
- The construction bite can be Horizontal (H) or Vertical (V) Activator.
- H Activator involves bringing the mandible forward by 6-7mm and opening it by 3-4mm.
- V Activator involves bringing the mandible forward by 2-3mm and opening it by 7-8mm.

Types of Activators and Headgear and Activator Therapy
- Kinetor Activator was developed by Hugo Stockfish and had latex tubing for stimulation.
- Bow Activator of A.M Schwarz used an elastic bow for periodic adjustment.
- Herrens Activator included clasps for stability and maximal sagittal advancement.
- LSU or Shaye Activator leveled the occlusal plane by having lower incisors bite on acrylic.
- Elastic Open Activator of G. Klammt replaced acrylic with wires for flexibility.
- Propulsor, U Bow Activator, Wunderer Activator, Hamilton Expansion Activator, and Cybernator are other types of Activators.
- LM-Activator is suitable for treatment in early mixed dentition and other stages of dental development.
- Headgear and Activator Therapy can be done using the Stockli-Teuscher Approach or Hickam Approach.

Note: The remaining bullet points have been omitted due to exceeding the limit of 5 bullet list items per subtopic.