BONE LOSS

•INTRODUCTIONINTRODUCTION

•ETIOLOGYETIOLOGY

•FACTORS DETERMINING BONE FACTORS DETERMINING BONE MORPHOLOGYMORPHOLOGY

•BONE DESTRUCTION PATTERNSBONE DESTRUCTION PATTERNS

INTRODUCTION :-INTRODUCTION :-

ETIOLOGYETIOLOGY :- :-

EXTENSION OF GINGIVAL INFLAMMATION

TRAUMA FROM OCCLUSION

SYSTEMIC DISORDERS

EXTENSION OF GINGIVAL INFLAMMATION

The most common cause of bone destruction in periodontal disease is extension of inflammation from the marginal gingiva into the supporting PD tissue.Periodontitis is always preceded by gingivitis, but not all gingivitis progresses to periodontitisThe transition from gingivitis to periodontitis is associated with changes in composition of bacterial plaque.

The recurrence of episode of acute destruction over time may be one mechanism leading to progressive bone loss in marginal gingivitis.The extension of inflammation is modified by pathogenic potential of plaque or resistance of host

•Degree of fibrosis of gingiva

•Width of attached gingiva

•Peripheral reactive fibrogenesis and osteogenesis .

•“walling off “ by fibrin-fibrinolytic system.

Histopathology

After inflammation reaches the bone by extension from the gingiva,it spreads into the marrow spaces

And replaces the marrow with leukocytic and fluid exudate,new blood vessel, & proliferating fibroblasts.

Multinuclear osteoclasts and mononuclear phagocytes increase in number ,the bone surfaces appear ,lined with howship’s lacunae.

In marrow spaces ,resorption proceed, causing a thinning of surrounding bony trabeculae and enlargement of marrow spaces

Destruction of bone and reduction in height

Radius of action

1.5 to 2.5 mm within which bacterial plaque induce loss of bone.

Interproximal angular defect can appear in spaces that are wider than 2.5 mm because bone marrow spaces would be destroyed entirely.

Rate of bone loss

Range of bone loss varies depending on the type of disease present.

Periods of destruction

• bursts of destructive activity associated with sub gingival ulceration and acute inflammatory reaction, resulting in rapid bone loss.

•Bursts of destructive activity coincide with the conversion of T-lymphocyte lesion to B-lymphocyte

•Exacerbation are associated with loose , unattached ,motile gram negative ,anaerobic pocket flora and period of remission coincide with the formation of dense ,unattached ,nonmotile, grame positive flora with tendency to mineralize.•Tissue invasion by one or several bacterial species is followed by an advanced local host defense that controls the attack.

Mechanisms of bone destruction

The factors involved in bone destruction in periodontal disease are bacteria and host mediated

And they produced osteoclasts and also direct effect by bacterial colonies

Several host factors released by inflammatory cells are prostaglandins , interleukin 1-alpha and beta ,and tumor necrosis factor

Bone formation in periodontal disease

Areas of bone formation are found adjacent to areas of bone resorption and along trabecular surfaces at a distance from the inflammation – BUTTRESSING BONE FORMATION

Intermittent bone formation and destruction.

Bone destruction caused by trauma from occlusion

Trauma from occlusion can produce bone destruction in absence or presence of inflammationIn the absence of inflammation the changes are caused by increased compression and tension of pdl and increased osteoclasis of alveolar bone to necrosis of pdl and bone and resorption of bone.

This changes are reversible which may cause angular shape bone loss.

In the presence of inflammation the changes cause bizarre patterns.

Bone destruction caused by systemic disorders

System influence on the response of alveolar bone has been termed as BONE FACTOR IN PERIODONTAL DISEASE ( IRVING GLICKMAN IN 1950 )

Relationship between periodontal bone loss and osteoporosis.

Osteoporosis is physiological condition of post menopausal women ,resulting in loss of bone mineral content and structrual bone changes.

Bone loss may also occur in generalized skeletal disturbances like hyperparathyroidism ,leukemia.

FACTORS AFFECTING BONE FACTORS AFFECTING BONE MORPHOLOGY IN PERIODONTAL MORPHOLOGY IN PERIODONTAL DISEASEDISEASE

Normal variation in alveolar bone

Exostoses

Trauma from occlusion

Buttressing bone formation

Food impaction

Juvenile periodontitis

BONE DESTRUCTION PATTERN :-BONE DESTRUCTION PATTERN :-

Horizontal bone loss

Most common pattern

It occurs when the path of inflammation is to the crest bone.

The crest of the bone is perpendicular to the tooth surface.

This type of bone loss produce suprabony pocket.

Vertical bone loss

Less common pattern

It occurs when the pathway of inflammation travels directly into the pdl space.

This type of bone loss produce infrabony pocket.

It occurs intradentally which can see on radiograrh.

It increases with age.

Osseous craters

Osseous craters are concavities in the crest of the interdentally bone confined within the facial and lingual walls

Reasons for high frequency :

The interdental area collects Plaque and is difficult to clean.Normal flat or even concave faciolingual shape of interdental septum in lower molar Vascular pattern

Bulbous bone contours

They are bony enlargements caused by exostoses,addeptation to function or butteresting boneThey are more in maxilla than mandible.

Reversed architectureThey are produced by loss of interdental bone including the facial plates, lingual plates Or both without concomitant loss of radicularbone.More in maxilla

ledgesLedges are plateau like bone margins caused by resorption of thickened bony plates.

Furcation involvement

Furcation refers to the invasion of the bifurcatoin and trifurcation of multirooted teeth by periodontal disease.Mandibular 1st molars are most common site and maxillary premolar are least common.Grade 1 – incipient bone lossGrade 2 – partial bone lossGrade 3 – total bone loss ( through & through opening of furcation

Grade 4 – similar to grade 3 but with gingival recession

Microscopically –

It is simply a phase of rootward extension of periodontal pocket

In its early stage , widening of the periodontal space with cellular and fluid exudates

Extension of the inflammation into the bone leads to bone resorption and reduction in height.

Bone destruction pattern may produced horizontal or angular , and very frequently crater develop in interradicular area.