[2] The obvious functional disabilities that arise from jaw abnormalities are very much physically seen as previously stated, but when considering these individuals it must be kept in mind that these conditions may well affect them psychologically; making them feel as though they are handicapped.

[3]  It is also of the utmost importance when correcting these mandibular anomalies that the teeth result in a good occlusion with the opposing dentition of the maxilla.

In order to correct mandibular anomalies it is common for a complex treatment plan which would involve surgical intervention and orthodontic input.

[12] Misalignment of teeth creates difficulties in head and neck functions related to chewing,[6][7][8] swallowing, breathing, speech articulation[6][7][8] and lip closure/posture.

[16] Diagnosis of a jaw deformity is a structured process, linking the undertaking of a history, physical examination of the patient, and appraisal of diagnostic studies.

This process may involve more than a single discipline of Dentistry – in addition to orthodontic and surgical needs, some patients may also require periodontal, endodontic, complex restorative, and prosthetic considerations.

The medical history includes questions on the general health of the patient, to assess contraindications to treatment of jaw abnormality.

Special emphasis is placed on diseases and medication which cause altered metabolism, that may affect growth and tissue reactions.

As the human skeleton is not visibly perceptible, bone deformity is inferred and evaluated by facial appearance and dentition.

Two other clinical indicators can be assessed when analysing vertical dimensions, namely the Frankfort Mandibular Planes Angle (FMPA) and the Lower Facial Height (LFH) – both of which are each recorded as either average, increased, or decreased.

It checks for the alignment of the soft tissue nasion, the middle part of the upper lip at the vermillion border, and the chin point.

[23] A false asymmetry arises due to occlusal interferences, which results in a lateral displacement of the mandible, producing a cross-bite in the anterior/buccal region.

The assessment of the transverse components of the facial width is best described by the "rule of fifths",[24] which sagittally divides the face into five equal parts:[25] It is insufficient to derive at a diagnosis of jaw deformity solely based on the clinical examination.

Hence, additional information is gathered from diagnostic tests, which may include dental model analyses and radiographic imaging studies.

Clinical appearance of some patients with congenital type of mandibular micrognathia can have a severe retrusion of the chin but by actual measurements, the mandible may be found to be within the normal limits of variation.

This may be 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.

[30] It can also be clinically presented when the glenoid fossa and condylar head is more anteriorly placed, causing mandibular prognathism.

Microgenia can be presented when there is inadequate bone depth at the apex of lower anteriors or the base of mandible and vice versa.

Whereas when assessing this clinically, one would measure the distance between the central incisors and the upper lip, which, in fact, denotes position rather than size.

In other words, EDD and IDD can either appear camouflaged or apparent given the skeletal base and the soft tissue profile accompanying it.

For example, the drape of the upper lip can mask the maxillary deficiency to such an extent that it presents as a normal soft tissue profile (REF).

[42] This is regarded as a ‘gummy smile.’ As alluded to previously, the paranasal region is important to consider when assessing a patient for IDD or EDD.

A lack of bony support for the soft tissues in this region will subsequently produce the depression, known as paranasal hollowing.

Maxillary deficiency usually manifests as an increased naso-labial angle, although this is not a credible indication due to factors such as a short upper lip and/or proclined incisors.

[46] On the week 8, the tongue will be withdrawn downwards and the right and left lateral palatal shelves will be rapidly elevated, flipped into a horizontal orientation and fuse together from the front to the back two.

[49] Some of the growth factors that can be implicated in the facial development resulting in craniofacial defect are BMP, FGF, Shh, Wnt and endothelins.

[48] Another environmental factors that has been actively involved in studies to prevent cleft lip and palate occurrences is the intake of folic acid during pregnancy.

[50] There are also studies in mice and dogs reported the protective effect of folic acid supplementation to prevent cleft lip palate occurrence.

Damage to the inferior alveolar bundle is avoided by sectioning the buccal and retromolar cortex of the mandible and the cancellous bone is carefully split.

[18]: 203 The Le Fort classification (which is used for fracture description) generally describes the surgical techniques which are used for maxillary surgery.