The key to success is to use an appliance that is both comfortable, easily retained and predictable such as a simple Hawley retainer with recurve springs or a fixed labial-lingual appliance (including a vertical removable arch for ease of adjustment with a recurve spring to jump the cross-bite). 

Both of these appliances work by tipping the maxillary teeth forward so they are in a normal dental relationship to the mandibular teeth. Once this is accomplished, it will allow future coordinated growth between the maxilla and the mandible

Optimum orthodontic force is one, which moves teeth most rapidly in the desired direction, with the least possible damage to tissue and with minimum patient discomfort. 

Oppenheim and Schwarz following extensive studies stated that the optimum force is equivalent to the capillary pulse pressure, which is 20-26 gm/sq. cm of root surface area. 

From a clinical point of view, optimum orthodontic force has the following characteristics: 
1) Products rapid tooth movement 
2) Minimal patient discomfort 
3) The lag phase of tooth movement is minimal 
4) No marked mobility of the teeth being moved 

From a histologic point of view the use of optimum orthodontic force has the following characteristics: 

1) The vitality of the tooth and supporting periodontal ligament is maintained 
2) Initiates maximum cellular response 
3) Produces direct or frontal resorption

According to Simon, in normal arch relationship, the orbital plane passes through the distal axial aspect of the maxillary canine

Malocclusions described as anteropostenor deviations based on their distance from the orbital plane are as follows:

1. Protraction: The teeth, one or both, dental arches, andYor jaws are too far forward, i.e. placed forward or anterior to the plane as compared to the normal where the plane passes through the distal incline of the canine.

2. Retraction: The teeth, one or both dental arches and/or jaws are too far backward, i.e. placed posterior to the plane than normal