Pruzansky IIb is a more severe subtype characterized by:
A small deformed hemi-mandible with a small ramus, pronounced antegonial notch and asymmetry of the chin (displaced to the affected side). The mandibular ramus and condyle is positioned medially.
A hypoplastic TMJ with the glenoid fossa abnormally placed medially. The distance between it and the midline is substantially less than on the unaffected side. Hence, the TMJ cannot be incorporated into the surgical construction. Generally the TMJ is not at the same vertical level as the normal side.
Occlusal cant upwards on the affected side. Varying degrees of severity will be observed. The occlusion may be class I, II or III, but the class II pattern predominates.
Note: The Pruzansky IIa/IIb classification does not take into account those cases where, in addition, part or all of the zygomatic arch is missing. There may be an indication for constructing the arch before any surgery is carried out to the mandible.
In addition to the above, the following may be found:
Every range of ear presentation is possible from a completely normally shaped and positioned external ear with normal middle ear and inner ear structures and normal hearing all the way through to complete anotia with conduction hearing loss.
The position of the orbit and the eye on the affected side can be normal but varying degrees of vertical and horizontal dystopia can occur. Microphthalmia and anophthalmia can also occur.
The soft tissues on the affected side of the face can exhibit a range of severity from effectively normal to severely hypoplastic or absent.
The branches of the facial nerve on the affected side can function completely normally but can also show a varying range of reduced function (palsy) from mild to severe and affecting one or more of the nerve branches.