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1. Bone loss & patterns of bone loss
INDIAN DENTAL ACADEMY
Leader in Continuing Dental Education
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2. Periodontitis is always preceded by the
gingivitis , but not all gingivitis progresses
to periodontitis
The transition of gingivitis to peridontitis is
associated with changes in the plaque
T lymphocytes are predominant in the
gingivitis, as the lesion becomes B
lymphocytic it becomes more destructive
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3. The recurrent episodes of acute destruction
over time may be lead to progressive bone
loss in marginal periodontitis
Pathway of inflammation
 Inflammation bone PDL
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4. Radius of action
 Locally produced bone
resorption factors have
to be present in the
proximity of bone
surface to be able to
exert their action
 Range of 1.5mm-
2.5mm within bacterial
plaque can induce loss
of bone
 Interproximal angular
defects can appear only
in spaces that are wider
than 2.5mm
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5.  Large defects far exceeding 2.5mm from the
tooth surface may be caused by presence of
bacteria in the tissues
Rate of bone loss
8 % --- 0.1 mm –1mm/yr
 81% --- 0.05mm-0.5mm/yr
 11% --- 0.05-0.09mm/yr
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6. Mechanisms of bone destruction
 Plaque bone progenitor cells
noncellular
mechanism
Gingival cells osteoclasts
mediators
Bone resorption
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7. Plaque direct action bone resorption
PGE2,IL-1 & TNF, IL-6 bone
resorption
NSAIDs such as flubiprofen , ibuprofen
inhibit PGE2, slowing bone loss.
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8. Bone destruction caused by systemic
disases
 Bone factor concept ---systemic component is
present in all forms of periodontitis. Nature of
systemic component influences the severity of
disease.
 Osteoporosis
 Hyperparathyroidism, leukemia.
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9. Factors that determine the bone morphology
in the alveolar bone
 Anatomic factors
 Thickness , width, & crest angulation of interdental
septa
 Thickness of facial & lingual alveolar bone
 Presence of fenestration, dehiscence or both
 Alignment of teeth
 Root position within the alveolar process
 Proximity with another tooth surface
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10.  Exostoses
 Lipping – Bone
formation occurs in an
attempt to buttress
bony trabeculae
weakened by
resorption. When it
occurs within the jaw it
is called central
buttressing bone
formation.when it
occurs in the external
surface , it is reffred as
peripheral buttressing
bone formation.
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11.  TFO --- funnel shaped
widening of crestal
portion of PDL, with
resorption of alveolar
bone.Angular shape
bony crest represent
adaptation of PDL
tissues to “cushion”
increased occlusal
force.
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12.  Food impaction --- it
is complicating factor
rather than cause of
bone defect
 JP
Bone destruction
patterns
 Horizontal bone loss
 Most common pattern
 Bone margin remains
perpendicular to the
tooth surface Horizontal bone loss
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13.  Angular or vertical
defects
 They occur in an
oblique direction
leaving an hollowed
trough in the bone
along side the root
 Base of the defect
located apical to
surronding bone
 They accompany
infrabony defects
 They classified on
number of osseous
walls present
 One wall
 Two wall
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Three wall

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15.  The number of walls in the apical portion of the defect
may be greater than that in its occlusal portion,
combined osseous defects
 Surgical exposure is the only sure way to determine the
configuration of osseous walls
 Vertical defects increases with age
 Intrabony defects are more frequently found on the
mesial surfaces of upper & lower molars
 About 60% of persons with interdental angular defects
have only a single defect
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17. Osseous craters
 These are the concavities in the crest of the
interdental bone confined within the facial &
lingual walls
 They form about 1/3 of all defects & 2/3 of
mandibular defects
 They are twice as common in posterior
segments as in anterior segments
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18.  Reasons for high
frequency of
interdental craters
 Interdental area collects
plaque & is difficult to
clean
 Vascular patterns from
the gingiva to the centre
of the crest may provide
a pathway of
inflammation
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19. Bulbous bone contours
 bony enlargements
caused by exotoses,
buttressing bone
formation.
 Found more frequently
in the maxilla than in
the mandible
Reversed architecture
 More common in the
maxilla
Reversed architecture
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20. Ledges
 Plateu like bone margins caused by resorption
of thickened bony plates
F.I.
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