N- The height and density of alveolar bone are
normally maintained by an equilibrium.
Regulated by local and systemic
influences , between bone formation and
When resorption exceeds formation, both
bone height and density is reduced
3. Causes of bone destruction-
(in periodontal disease)
1) Extension Of Gingival Inflammation
2) Trauma from occlusion(TFO)
3) Systemic disorders
4. 1) Bone Destruction Caused By
Extension Of Gingival
“Periodontitis is always preceded by gingivitis,
but not all gingivitis progress to periodontitis”
Most common cause
Extension of inflammation
from marginal gingiva to
5. The transition from gingivitis to
periodontitis is associated with changes
in composition of bacterial plaque.
Coccoid rods ,
Plasma cells PMNs
6. HISTOPATHOLOGY :
Area of inflammation extending from
gingiva into suprabony area.
course : along collagen bundle fibres,
blood vessels, loosely arranged tissues.
8. After inflammation reaches the bone, it spreads into
the marrow spaces and replaces the marrow with a
leukocytic and fluid exudate, new blood vessels and
Multinuclear osteoclasts and mononuclear
phagocytes increase in number, and the bone
surfaces appear, lined with Howship lacunae.
In the marrow spaces, resorption proceeds from
within, causing a thinning of the surrounding bony
trabeculae and enlargement of the marrow spaces,
followed by destruction of the bone and a reduction
in bone height .
10. RATE OF BONE LOSS
Loe et al in 1986 , found rate of
bone loss to average about
# 0.2 mm/year for facial surfaces
# 0.3 mm/year for proximal
when periodontal disease was
allowed to progress untreated .
11. PERIODS OF DESTRUCTION-
Periodontal destruction occurs in
episodic and intermittent manner.
Periods of inactivity &
Destructive activity , results in,
loss of collagen & alveolar bone.
Followed by an advanced host
defense that controls the attack.
12. MECHANISM OF BONE
Inhibit action of
13. 2) BONE DESTRUCTION
CAUSED BY TRAUMA FROM
Periodontal response to the
TFO can occur in presence or
absence of inflammation.
In the absence, effects on
alveolar bone ranges from
resorption to necrosis.
Persistent TFO results in
angular defects of the bone.
14. When combined with inflammation,
i.e. ZONE OF CO-DESTRUCTION,
Plaque induced inflammation entering into the zone of
trauma from occlusion(supporting structures).
Results in angular bone defects, bizarre bone pattern.
15. 3) BONE DESTRUCTION
CAUSED BY SYSTEMIC
Possible relationship between periodontal bone
loss and systemic disorders.
OSTEOPOROSIS : loss of bone mineral content
and structural bone changes. Risk factors-
OSTEOPENIA : tooth mobility and tooth loss
16. FACTORS DETERMINING BONE
MORPHOLOGY IN PERIODONTAL
1) Normal variation of alveolar bone :
a) thickness,width,crestal angulation of
b) thickness of facial & lingual septa
c) presence of fenestrations &
17. 2) Exostoses :
a) overgrowths of bone
b) they can occur as small or large
nodules, sharp ridges , spike-like
18. 3) TFO :
a) thickening of cervical margin of
b) angular defects or buttressing bone.
19. c) buttressing bone formation occurs
during the repair phase of TFO
d) host reinforces thin trabeculae with
e) when it occurs within the jaw , it is
central buttressing bone formation.
f) when it occurs on external surface,
peripheral buttressing bone formation.
g) results in bulbous bone
contours(lipping) and osseous craters.
20. 4) Food impaction :
a) interdental bone defects occur
when there is abnormal or absence of
b) food impaction here , results in
inverted bone architecture.
5) Aggressive periodontitis :
a) vertical or angular bone defects.
21. BONE DESTRUCTION
1) Vertical or angular defects
2) Osseous craters
3) Bulbous bone contours
4) Reverse architecture
6) Furcation involvement
22. Horizontal bone loss :
a) most common pattern
b) bone height reduced, but margin
remains perpendicular to tooth surface.
23. Vertical bone loss :
a) angular defects , occur in an oblique
b) leads to hollowed-out trough in the bone
c) Depending on number of walls present ,
angular defects were classified by Goldman
and Cohen (1958) as,
24. (i) Three osseous walls
(ii) Two osseous walls
(iii) One osseous wall
25. Osseous craters :
a) concavities in the crest of interdental
bone confined within faciolingal walls.
b) Reasons :
(i) plaque accumulation and difficulty to
(ii) normal concavity in lower molars
(iii) vascular patterns from gingiva to
crest, a pathway for
26. Bulbous bone contours :
a) bony enlargement
b) an adaptation to Exostoses
c) adaptation to function or buttressing
27. o Reversed architecture :
produced by loss of interdental bone,
facial and lingual plates without concomitant
loss of radicular bone.
28. Furcation involvement :
Invasion of bifurcation or trifurcation of
multirooted teeth by periodontal disease.
(i) Grade 1 : incipient bone loss
(ii) Grade 2 : partial bone loss
(iii) Grade 3 : total bone loss with through
and through opening of furcation
(iv) Grade 4 : similar to grade 3,with gingival
recession exposing the furcation to view.
30. Ledges :
(a) plateau-like bony margins
(b) caused by resorption of thickened
Although periodontitis is an infectious
disease of the gingival tissue , changes that
occur in bone are crucial because
destruction of bone is responsible for tooth
Bone loss patterns associated with
periodontal disease is varied and the type of
management depends upon the type of loss.