Therefore, in order to ‘harmonize with geometry’, EDD and IDD are now used widely.Vertical and Horizontal Mandibular Excess:
Simply put, excessive vertical growth is the term used for when the mandible is considered ‘too far down. Whereas in excessive horizontal growth the opposite applies, where the mandible is growing in a more horizontal pattern, in relation to the maxilla. The primary cause of the above two abnormalities in adolescents is due to accelerated and slow mandibular growth. Resulting in either a longer lower face height appearance (vertical growth) or a shorter one (horizontal growth). The length between the columella (base of the nose) and menton (base of the chin) is the variable measurement. This is in relation to the length between the glabella (between eyebrows) and the columella. In a normal case, these lengths would be equal or without a major discrepancy. However, in excess vertical and horizontal growth, the proportions vary and do not equal. The development of the mandible is such that it ossifies in two primary ways; endochondrally and intramembranously. Almost the entire mandible is formed via intramembranous ossification, with just the condyle ossifying endochondrally. This allows the condyle to resist forces exerted on it.
This maybe because a posterior placing of the condylar head with regard to the skull or to a steep mandibular angle resulting in an evident jaw retrusion. The acquired type of micrognathia occurs after birth and usually is an effect of a disturbance to temporomandibular joint. Growth of mandible depends on the normally developing condyles and the muscle function For example, trauma or infection that affect mastoid, middle ear or the joint will result in ankylosis of temporomandibular joint leading to mandibular micrognathia. MacronagthiaMacronagthia is a condition of abnormally large jaws. The jaw size is usually proportion to the increase in skeleton size. It is usually due to excessive growth of the mandible and can have features including reverse maxillary to mandibular relationship, reverse overjet or absence of overbite. It can also be clinically presented when the glenoid fossa and condylar head is more anteriorly placed, causing mandibular prognathism. Macronagthism can be associated with other medical conditions :-
1. Pagets disease where there is overgrowth of the maxilla, cranium and mandible2. Acromegaly, an endocrine disease, can present with enlargement of bones with growth potential such as the mandible, thickened soft tissues and facial features and spade-like hands 
Macrogenia or MicrogeniaMacrogenia and microgenia occur when there is a normal skeletal relationship but the chin, skeletal and soft tissue components, failed to develop in proportion to the skeletal base, resulting in marked protrusive (macrogenia) or retrusive (microgenia) facial profile.