Define

Define :
1- Dental caries
It is an infectious microbial disease characterized by
a demineralization of the calcified tissues of the
inorganic portion and destruction of the organic
substance of the tooth.
2- Attrition
It is a mechanical loss of hard tooth substance
resulting from friction between the opposing teeth
with no foreign substances intervening. It is
commonly seen in anterior teeth. Bruxism is a
common cause of pathologic wear.
3- Abrasion
It is a mechanical loss of hard tooth structure through
abnormal mechanical processes involving foreign
objects introduced in the mouth and contacting the
teeth as hard tooth brush.
4- Erosion
It is a chemico-mechanical loss of hard tooth
substance resulting from direct chemical action on
the tooth surface with the absence of bacteria.
5- Abfraction
It is a wedge shaped defect at the cementoenamel
junctionof the tooth. This lesion may be observed on
a single tooth or non adjacent teeth. This occur when
the tooth is subjected to strong stresses and these
forces
are
concentrated
at
CEJ
creating
microfractures in enamel and dentin which are
thought to propagate with time perpendicular to the
long axis of the stressed teeth until enamel and
dentin break away.

Classification of dental caries:
a) According to location:
1. Pits ang fissure caries.
2. Smooth surface caries.
b) According to rapidity of the process:

1. Acute caries (rapid).
2. Chronic caries (slow).
c) According to whether the surface is new or
whether it was previously filled and caries occurred
around the margins of the filling
1. Primary caries (Virgin).
2. Secondary caries (recurrent).
d) Black's classification:
1. Class I: it is a pits and fissure caries that occurs
in the occlusal surface of molars and premolars,
occlusal two-third of the buccal and lingual
surfaces of molars and in the palatal surfaces of
upper incisors.
2. Class II: Smooth surface cavities that occur in
the proximal surfaces of molars and premolars.
3. Class III: Smooth surface cavities that occur in
the proximal surfaces of anterior teeth not
including the incisal angle.
4. Class IV: Smooth surface cavities that occur in
the proximal surfaces of anterior teeth including
the incisal angle.
5. Class V: Smooth surface cavities that occur in
the gingival third of the buccal and lingual
surfaces of all teeth.
6. Class VI: it is found on the tips of cusps or along
the biting edges of incisors .
e) According to the number of surfaces affected by
caries:
1. Simple cavities: are cavities occurring in one
surface only.
2. Compound cavities: involving two surface e.g.
occluso-mesial.
3. Complex cavities: involving more than two
surfaces e.g. mesio-occluso-distal.
f) Mount and Hume's classification:
It is based on the site and the size of the lesion

The three sites are
Site1: pits and fissures and enamel defects.
Site2: proximal enamel surfaces.
Site3: the cervical one third of the crown or the
exposed root.
The four sizes are:
Size1: minimal dentin involvement.
Size2: moderate dentin involvement.
Size3: enlarged dentin involvement.
Size4: extensive involvement of caries and bulk
loss of tooth structure.