It is proposed this hearing loss is a secondary feature to attrition; this type of tooth wear can cause jaw overclosure with subsequent changes to the shape of the inner ear, thus causing hearing loss. However, the true cause remains unknown. Type III
Similar clinical and radiographic features to that of type I and II are apparent for the adult (permanent) teeth. The main distinguishing feature is "shell teeth", a term used to describe the unique appearance of the baby (primary) teeth; the primary teeth have multiple pulp exposures and radiographically appear hollow as the dentine layer is thin (dentine hypotrophy) and the pulp chamber is very large. Histology
The enamel has a regular structure, however, there are abnormalities in the structure of dentine and at the amelo-dentinal junction. These abnormalities include:

Fewer dentinal tubules
Dentinal tubules may be of smaller diameter, irregular in shape, and may also be obliterated
Abnormal morphology of apatite crystals
Higher water and collagen content in the organic component of dentine (see Structure section on dentin page to learn more)

Diagnosis
To determine if the condition has been inherited, it is suggested to ask if any other family member has Dentinogenesis imperfecta.
An advanced case is usually readily apparent to the examiner, and can provide for an unambiguous diagnosis prior to more specialized testing. Under close examination, a ring of yellow-brown to olive-green pigmentation known as a Fleischer ring can be observed in around half of keratoconic eyes. The Fleischer ring, caused by deposition of the iron oxide hemosiderin within the corneal epithelium, is subtle and may not be readily detectable in all cases, but becomes more evident when viewed under a cobalt blue filter. Similarly, around 50% of subjects exhibit Vogts striae, fine stress lines within the cornea caused by stretching and thinning. The striae temporarily disappear while slight pressure is applied to the eyeball. A highly pronounced cone can create a V-shaped indentation in the lower eyelid when the persons gaze is directed downwards, known as Munsons sign. Other clinical signs of keratoconus will normally have presented themselves long before Munsons sign becomes apparent, and so this finding, though a classic sign of the disease, tends not to be of primary diagnostic importance. A handheld keratoscope, sometimes known as "Placidos disk", can provide a simple noninvasive visualization of the surface of the cornea by projecting a series of concentric rings of light onto the cornea. A more definitive diagnosis can be obtained using corneal topography, in which an automated instrument projects the illuminated pattern onto the cornea and determines its topography from analysis of the digital image.