Definition : Refers to irreversible and inevitable
change that occurs with time
It is also defined as sum of all morphological and
functional alteration in an organism that leads to
BIOLOGICAL AGING PROCESS IS :
Universal : detectable in all members of the
Progressive: develop gradually and
Deleterious : harmful to the survival of
Change in permeability
Chemical and surface
Physiological wear of occlusal or incisal and
proximal surfaces of teeth resulting in a
decrease in vertical dimension
In severe attrition dentin may be exposed
CHANGE IN PERMEABILITY
Young enamel acts as a semi-permeable
membrane and permits slow passage of water
and molecular substances through the pores
between the crystals.
With age the enamel crystals grow in size and
the pores between them is obliterated
resulting in reduced permeability of the
Normal: white to
With age darkening seen.
Thought to be because of:
I. Loss of enamel rods-
this loss alters the light
reflection of enamel
and results tooth color
II. Deepening of dentin
color seen through
layer of enamel.
CHEMICAL AND SURFACE CHANGES
Increase in fluoride and nitrogen content.
Water and organic content decrease with age.
Reduction in organic content reduces chance
of caries in teeth with age.
Loss of Perikymata
The main changes in dentin associated
with aging are
Increase in sclerotic dentin.
Increase in the number of dead
Increase in formation of reparative
and reactive dentin.
Vitality of dentin
In normal dentin the odontoblastic
processes may disintegrate and the
empty tubules get filled with air. These
are called dead tracts.
They appear black in transmitted light
and white in reflected light.
In narrow pulpal horns degeneration of
odontoblast seen due to crowding of
thought to be the initial step in the
formation of sclerotic dentin.
Refers to the dentinal tubules that have
become occluded with calcified materials.
It may be result of the aging process and
called physiologic dentin sclerosis or may
occur due to some irritation like caries,
attrition, abrasion and called reactive dentin
When this occurs in several tubules in the
same area , the dentin assumes a glassy
appearance and become transparent
Most common in
apical 3rd of the root.
light in transmitted
light and dark in
REPARATIVE –REACTIVE DENTIN
If the provoking stimulus cause destruction
of the original odontoblasts, the new, less
tubular dentin formed by newly
differentiated odontoblast like cells is called
However if the odontoblast survive the
provoking stimuli the dentin produced by
them is called Reactionary dentin
VITALITY OF DENTIN
Since the odontoblasts do not degenerate
normally, dentin is laid down throughout life.
Although after the teeth have erupted and
become functional dentinogenesis slows and
further dentin formation is at much slower
Change in permeability.
Cementum re-absorption and
It is an abnormal thickening of the cementum.
may be generalized or localized ,diffused or
Hypercementosis is termed cementum
hypertrophy if the overgrowth improves the
functional qualities of the cementum and is
termed cementum hyperplasia if it is not
correlated with increased function.
They are ovoid or round
calcified structure that are
formed as a result of
calcification of the
tissue or the epithelial
rests of Malssez.
Cementicles may be:
1. Free in the periodontal
2. Attached the cementum
3. Embedded in the
Permeability : The permeability of cementum
decreases gradually by age.
The permeability from the periodontal side is lost except in
the most recently formed layer of cementum, while that
from the dentine side remains only in the apical region.
Cementum Resorption and Repair: Cementum
resorption can occur after trauma or excessive occlusal
After resorption ceases, the damage is usually repaired.
If the repair establishes the former outline of the root
surface it is called anatomic repair. However if only a thin
layer of cementum is deposited and the root outline is not
constructed it is called functional repair.
Bone resorption is
the major age
change in alveolar
Common site of
aspect of alveolar
height and width
of the jaw
the crest of the
alveolar bone and
The marrow space have fatty infiltration.
Loss of maxillary bone is accompanied by
increase in size of maxillary sinus.
Internal trabecular arrangement is more open
which indicate bone loss.
Orban’s oral histology and embryology
Ten Cate’s oral histology
Oral anatomy ,histology and embryology
Berkovitz , Holland , Moxham