Jaw abnormality sagittally divides the face into five equal parts: 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. Mandibular micrognathia is the condition when lower jaw is smaller than normal. Failure of the ramus to develop will give rise to micrognathia.<ref name="Elsevier/Churchill Livingstone"></ref> Micrognathia can be classified as either congenital or acquired. Clinical appearance of some patients with congenital type of mandibular micrognathia can have a severe retrusion of the chin but by actual measurements,
Phossy jaw doctor or dentist could see changes in the jaw bones through radiographs or x-rays. The sequestra, the part or parts of the bone that dies and breaks off are light in terms of weight and yellow to brown in color. The phossy jaw can be clearly demarcated from similar entities by radiographs. In radiographs, the sequestra present as a typical worm-eaten appearance similar to a pumice stone. Sequestra appear osteoporotic and decalcified. Separation of the dead bone from the surrounding bone appears clearly demarcated in the radiographs. The first case of phossy jaw was diagnosed by physician Lorinsor of Vienna