usually occur in three areas: in the fissures on the occlusal surface,
on the neck (lingual and buccal), and on the neck between teeth.
enamel is composed of calcium apatite and very little organic matter.
Once the decay gets through this hard outer shell, the other tissues
inside, including dentine and the pulp, are rapidly consumed.
Once the decay reaches the pulp, it is called
pulpitis, and is
the main source of pain associated with caries. Untreated pulpitis
leads to death of the pulp and the spread of infection into the
periapical tissues. Pulp can also die due to trauma.
No lesions 2) "white spot", some demineralization 3) broken enamel
surface, "lesion" 4) filling surrounded by more lesion
5) demineralization undermining tooth
fracture due to decay