BY-

J.RAHUL RAGHAVENDER

IV YEAR

INTRODUCTIO

N- The height and density of alveolar bone are

normally maintained by an equilibrium.

Regulated by local and systemic

influences , between bone formation and

resorption.

When resorption exceeds formation, both

bone height and density is reduced

Causes of bone destruction-(in periodontal disease)

1) Extension Of Gingival Inflammation

2) Trauma from occlusion(TFO)

3) Systemic disorders

1) Bone Destruction Caused By

Extension Of Gingival

Inflammation

“Periodontitis is always preceded by gingivitis, but not all gingivitis progress to periodontitis”

Most common cause

Extension of inflammation

from marginal gingiva to

supporting tissues.

The transition from gingivitis to

periodontitis is associated with changes

in composition of bacterial plaque.

GINGIVITIS PERIODONTITIS

COMP. OF

PLAQUE

Coccoid rods ,

straight rods

spirochetes

CELLS

(By Heijl)

Plasma cells PMNs

HISTOPATHOLOGY :

Area of inflammation extending from

gingiva into suprabony area.

course : along collagen bundle fibres,

blood vessels, loosely arranged tissues.

PATHWAYS OF

INFLAMMATION :

Facially and

Lingually,

1) Gingiva to outer

periosteum

2) Periosteum to

bone

3) Gingiva to PDL

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 proliferating fibroblasts.

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 .

RADIUS OF ACTION-

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 .

PERIODS OF DESTRUCTION-

Periodontal destruction occurs in episodic and intermittent manner.

Periods of inactivity & destruction.

Destructive activity , results in, loss of collagen & alveolar bone.

Followed by an advanced host defense that controls the attack.

MECHANISM OF BONE

DESTRUCTION-

Bone destruction

Bacterial

Differentiation of bone progenitor

cells into osteoclasts

Inhibit action of osteoblasts

Host-mediatedReleases PGE2,

IL-1α,IL-1β,TNF-α

2) BONE DESTRUCTION

CAUSED BY TRAUMA FROM

OCCLUSION - Periodontal response to the

external force.

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.

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.

3) BONE DESTRUCTION

CAUSED BY SYSTEMIC

DISORDERS - Possible relationship between periodontal bone

loss and systemic disorders.

OSTEOPOROSIS : loss of bone mineral content and structural bone changes. Risk factors-ageing,smoking,etc

OSTEOPENIA : tooth mobility and tooth loss

Hyperparathyroidism, leukopenia

FACTORS DETERMINING BONE

MORPHOLOGY IN PERIODONTAL

DISEASE-1) Normal variation of alveolar bone :

a) thickness,width,crestal angulation of interdental septa

b) thickness of facial & lingual septa

c) presence of fenestrations & dehiscences

2) Exostoses :

a) overgrowths of bone

b) they can occur as small or large

nodules, sharp ridges , spike-like

projections.

3) TFO :

a) thickening of cervical margin of

alveolar bone.

b) angular defects or buttressing bone.

c) buttressing bone formation occurs

during the repair phase of TFO

d) host reinforces thin trabeculae with

new bone

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.

4) Food impaction :

a) interdental bone defects occur

when there is abnormal or absence of

proximal contact.

b) food impaction here , results in

inverted bone architecture.

5) Aggressive periodontitis :

a) vertical or angular bone defects.

BONE DESTRUCTION

PATTERN -

1) Vertical or angular defects

2) Osseous craters

3) Bulbous bone contours

4) Reverse architecture

5) Ledges

6) Furcation involvement

Horizontal bone loss :

a) most common pattern

b) bone height reduced, but margin

remains perpendicular to tooth surface.

Vertical bone loss :

a) angular defects , occur in an oblique

direction

b) leads to hollowed-out trough in the bone

alongside root.

c) Depending on number of walls present , angular defects were classified by Goldman

and Cohen (1958) as,

(i) Three osseous walls

(ii) Two osseous walls

(iii) One osseous wall

(iv) Combination

Osseous craters :

a) concavities in the crest of interdental

bone confined within faciolingal walls.

b) Reasons :

(i) plaque accumulation and difficulty to

clean.

(ii) normal concavity in lower molars

(iii) vascular patterns from gingiva to

crest, a pathway for

inflammation

Bulbous bone contours :

a) bony enlargement

b) an adaptation to Exostoses

c) adaptation to function or buttressing

bone formation.

o Reversed architecture :

produced by loss of interdental bone,

facial and lingual plates without concomitant

loss of radicular bone.

Furcation involvement :

Invasion of bifurcation or trifurcation of multirooted teeth by periodontal disease.

Clinical features-

(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.

Ledges :

(a) plateau-like bony margins

(b) caused by resorption of thickened

bony plates

CONCLUSIO

N- 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

loss.

Bone loss patterns associated with

periodontal disease is varied and the type of

management depends upon the type of loss.