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Table 1: General treatment strategies based on
the Pruzansky‑Kaban classification of mandibular
abnormalities
Pruzansky-Kaban Treatment strategies
type
Type I Orthognathic surgical correction “facial
rotation” after orthodontic alignment,
[9]
coordination and decompensation. Standard
le Fort I, bilateral sagittal split osteotomies,
and sliding genioplasty techniques are used
Type IIa Surgery is only performed early at the
age of 4 and older, when there is a centric
occlusion-centric relation shift of more
than 5 mm. The surgery involves joint
a b reconstruction with costochondral grafting
Figure 5: Pruzansky-Kaban Type IIa. The mandibular ramus, condyle, Osteodistraction in the horizontal (not
and temporomandibular joint are present but hypoplastic and abnormal vertical) ramus is performed when there is
in shape. The mouth can be symmetrically opened. (a) Profile view insufficient bone stock to perform a sagittal
of the affected side in an adolescent girl; (b) three-dimensional (3D) split osteotomy after puberty
reconstruction of a multi-slice computed tomography (CT) scan of the
viscero-cranium of the patient in a, demonstrating the abnormal shape Orthognathic surgical correction “facial
and hypoplasia of the vertical ramus of the mandible rotation” after orthodontic alignment,
coordination, and decompensation is
performed at puberty and later
Type IIb and III Joint and ramus reconstruction at the age of
4 and older. Orthognathic surgical correction
“facial rotation” after orthodontic alignment,
coordination and decompensation, at
puberty and later

be stretched more easily when the process occurs
a b c gradually. After the latter procedure, vertical ramus
lengthening is easier to perform, as more bony overlap
allows for more stable osteosynthesis and improved
healing.
Point 3: Choice of the pivot
Rotation of the maxilla around a sagittal axis determines
the correction of the occlusal plane cant and helps to
swing the mandible to the midline [Figure 12]. The
d dental midlines are translated toward the healthy side
Figure 6: Pruzansky-Kaban Type IIb. The mandibular ramus is hypoplastic for alignment with the predetermined facial midline.
and markedly abnormal in form and location, being medial, anterior and Finally, the chin point is adjusted in a translational way
inferior. There is no articulation with the temporal bone. (a) Frontal view
of an affected adolescent; (b) profile view of the affected side of the girl to correct the skeletal mandibular midline. The chin point
in (a); (c) three-dimensional (3D) reconstruction of a multi-slice computed is often also rotated along a sagittal axis to deal with the
tomography (CT), submento-vertical view, demonstrating the abnormal symphyseal height difference.
structures in abnormal location (the same patient as in (a) and (b));
(d) orthopantomogram of the girl in (a), (b), and (c), showing downward Disimpacting the affected side necessitates a bone graft,
growth of the skull base on the affected side and no articulation
obtained from the calvarium or iliac crest. Impacting the
healthy side does not stretch the fibrous remains of the
masticatory muscles on the other side and is possible only
when a gummy smile exists on that side [Figure 13]. The
decision for the pivot relates to aesthetic desiderata (normal
tooth-to-incisor distance and limited gummy smile) and
functional desiderata (anti-relapse biomechanics). Hence,
the pivot can be located at one of three positions: at the
zygomatic buttress of the healthy side, at the zygomatic
buttress of the affected side, or at the nasal spine. Pivoting
a b at the affected side (and hence impacting at the healthy
Figure 7: Pruzansky-Kaban Type III. The mandibular ramus, condyle, and side) provides the least risk of relapse.
temporomandibular joint are absent. The lateral pterygoid muscle and
temporalis muscle, if present, are not attached to the mandibular remnant. Point 4: Skeletal suspension
(a) Three-fourths profile view of an affected girl; (b) three-dimensional (3D) Skeletal suspension is mandatory to control the
reconstruction of a multi-slice computed tomography (CT) scan of the correction of the occlusal plane cant and the dental
same girl as in a, showing the absence of the vertical ramus. The patient
also had a unilateral cleft lip, alveolus, and palate midline during healing [Figure 14]. As most cases of
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