There are essentially 3 alternatives for treating any skeletal malocclusion –
(i) growth modification
(ii) dental camouflage
(iii) orthognathic surgery Growth modification should be opted wherever applicable because this precludes the need for both tooth extraction and surgery.
Goal of growth modification is to alter the unacceptable skeletal relationships by modifying the patients remaining facial growth to favorably change the size or position of the jaws. There are 3 types of orthodontic appliances that can be used for modifying the growth of maxilla/mandible- (i) orthopedic appliances (ii) functional appliances (iii) inter arch elastic traction This seminar discusses the essential aspects of orthopedic appliances.
Orthopedic appliances generally use teeth as “handles” to transmit forces to the underlying skeletal structures. Basis of orthopedic appliance therapy resides in the use of intermittent forces of very high magnitude. Such heavy forces when directed to the basal bone via teeth tend to alter the magnitude & direction of the jaws by modifying the pattern of bone apposition at periosteal sutures & growth sites.
Orthopedic appliances are worn intermittently for only about 10-12 hours a day. Tooth movement is also reduced significantly by replenishment of normal circulation when the appliance is not worn. Thus, skeletal changes rather than tooth movement occur during orthopedic appliance therapy, although some tooth movement is inevitable.
The following are the commonly used orthopedic appliances –
a) Headgears b) Protraction Face Mask c) Chin Cup Appliance
Headgears are the most widely used extra oral orthopedic appliances. They are mainly used in the management of skeletal class II malocclusion by growth modification. They are also used for distalization of maxillary molars.
also called as “reverse pull headgear” or “protraction headgear” When an anterior protractory force is required, a protraction headgear is used. Principle – pulling force on the maxillary structures with reciprocal pushing
Also referred to as chin cap. It is an extra oral orthopedic device that covers the chin and is connected to a head gear. Used to restrict the forward and downward growth of the mandible. Types of chin cups Chin cups are of two types :
1. Occipital pull chin cup
2. Vertical pull chin cup