1. BONE LOSS & PATTERNS OF BONE DESTRUCTION
Department of Periodontics

2. Changes that occcur in bone are crucial because the destruction of bone is responsible for tooth loss
Bone height Bone density
Local factors
Systemic factors

3. CAUSES OF BONE DESTRUCTION
EXTENSION OF GINGIVAL INFLAMMATION
TRAUMA FROM OCCLUSION
SYSTEMIC DISORDERS
BONE MORPHOLOGY

4. AS AN EXTENSION OF GINGIVAL INFLAMMATION
Periodontitis is always preceded by gingivitis,but not all gingivitis progress to periodontitis
Transition from gingivitis to periodontitis is associated with changes in composition of bacterial plaque

6. Gingival inflamation collagen fibre bundles
1.HISTOPATHOLOGY
Gingival inflamation collagen fibre bundles
Blood vessels
Alveolar bone
Marrow spaces
Resorption
Thinning of surrounding bone &enlargment of marrow spaces
DESTRUCTION OF BONE(bone height)

7. After inflammation reaches bone__spreads into marrow spaces(replaces it with) leukocytes,fluid exudate,new blood vessels Multinuclear osteoclast& mononuclear phagocytes bone surface is lined with Howships lacunae Thinning of surrounding bone

8. 2.RADIUS OF ACTION Suggested by :PAGE & SCHROEDER* 1.5 to 2.5mm
Distance between the CEJ & crest of the alveolar bone ranges from
0.75 to 1.49mm(average-1.08mm)
Suggested by :PAGE & SCHROEDER*
1.5 to 2.5mm
Within which bacterial plaque induces bone loss

9. 3. RATE OF BONE LOSS LOE & CO-WORKERS Based on interproximal loss of attachment (yearly loss of attachment)
Approximately 8% - 0.1to 1mm(severe)
Approximately 81% to 0.5mm(moderate)
Approximately 11% -0.05to 0.09mm(less)

10. 4.PERIODS OF DESTRUCTION
Occurs in an episodic , intermittent fashion with periods of inactivity or quiesence.
Results in loss of collagen and alveolar bone with deepening of periodontal pocket.

11. 5.MECHANISM OF BONE DESTRUCTION
Host associated factors
Role of bacteria

12. BACTERIAL CAUSE :
Plaque products can also act directly on osteoblast or their progenitor , reducing their number.

13. BACTERIA Gram +ve Gram _ve Aerobic anaerobic
Eg.Streptococcus sp Eg P.intermedia,
Actinomyces sp P.gingivalis,
A.actinomycetemcomitans
Bacterial activity:
Releases endotoxin IgA & IgG degrading protease.
Leukotoxin.

14. HOST FACTORS INFLAMATORY MEDIATORS
Macrophages/fibroblast :Prostaglandin (osteoclastic bone resorption)
Macrophages,lymphocyte :Interleukin (osteoclast activating factor)
Macrophage :TNF (stimulation of bone resorption)
CYTOKINES

15. 6.BONE FORMATION IN PERIODONTAL DISEASE
Areas of bone formation are found immediately adjacent to sites of active bone resorption.
In effort to reinforce the remaining bone there is ‘buttressing bone formation’.

16. Bone formation reflects changes in gingival inflammation with changes in extent of bleeding , amount of exudate and composition of bacterial plaque

17. CAUSED BY TRAUMA FROM OCCLUSION When occlusal forces exceeds that of adaptive capacity of tissues ,tissue injury results.
Can happen in:
INFLAMMATION
presence
absence

18. Absence of inflammation
TRAUMA FROM OCCLUSION(PERSISTENT)
INCREASED COMPRESSION & TENSION OF PDL
INCREASED OSTEOCLASIS OF ALVEOLAR BONE
RESORPTION OF BONE & TOOTH STRUCTURE
FUNNEL SHAPED WIDENING OF CRESTAL PORTION OF PDL
TOOTH MOBILITY

19. Presence of inflamation
Aggravates bone destruction
bizzare bone pattern
Results in

20. CAUSED BY SYSTEMIC DISORDERS
OSTEOPOROSIS
HYPERTHYROIDISM
LEUKEMIA
OTHER FACTORS: AGING
SMOKING

21. BONE MORPHOLOGY AS A FACTOR IN PERIODONTAL DISEASE
Normal variations in alveolar bone
Exostoses
Trauma from occlusion
Butressing bone formation
Food impaction
Juvenile periodontitis

22. Normal variations in alveolar bone
Thickness, width & angulation of interdental septa
Thickness of facial & lingual alveolar plates
Fenestration & dehisence
Allignment of teeth
Root & root trunk anatomy
Root position
Proximity with another tooth surface

23. BONE DESTRUCTION PATTERNS
HORIZONTAL BONE LOSS
VERTICAL BONE LOSS
INTRABONY DEFECTS
OSSEOUS CRATERS
FURCATION
BONE ARCHITECTURE TYPES
BULBOUS BONE CONTOUR

24. HORIZONTAL BONE LOSS Most common.
Bone is reduced in height but bone margins remain perpendicular to tooth surface.
Interdental septa, facial & lingual plates are affected.

25. VERTICAL/ANGULAR DEFECTS
Occurs in oblique direction with base of defect located leaving a hollowed out trough apical to the crest of the bone.
Accompanied with intrabony pockets.
Increases with age.
Common in mesial & distal surface.

26. INTRABONY DEFECT FURTHER CLASSIFIED
Combined osseous defect
ONE
WALLED
One walled
COMBINED
OSSEOUS
DEFECT
THREE
WALLED
TWO
WALLED
Three walled
Two walled

28. Further classification
THREE WALLED DEFECT: Intrabony defect
common in mesial &
distal surface of molars.
TWO WALLED DEFECT :2 wall surrounding defect.

29. Further classification …
ONE WALLED DEFECT : Hemiseptum.
one wall is present.
COMBINED OSSEOUS
DEFECT :Horizontal along with vertical bone loss is present.

30. OSSEOUS CRATERS
Bone loss resulting in concavities on the crest of interdental bone confined within facial & lingual walls.

31. LEDGES
Plateau like bone margins caused by resorption of thickened bony plates.

32. FURCATIONS
Loss of radicular bone in interradicular space

33. REVERSED BONE ARCHITECTURE
Presence of loss of interdental bone including facial and lingual plates.

34. Positive architecture: Radicular bone is apical to. interdental bone
Positive architecture: Radicular bone is apical to interdental bone. Negative architecture: interdental bone is more apical than radicular bone. Flat architecture: Interdental bone is in same height with radicular bone

35. BULBOUS BONE CONTOUR They are bony enlargements caused by : Exostoses
Adaptation to function
Butressing bone formation

36. CONCLUSION
The key factor in achieving a good periodontal health lies in maintaining a good oral hygiene. Early & prompt diagnosis and treatment of gingival diseases will reduce the incidence of periodontal disease thereby ,reducing the bone destruction & avoiding tooth loss.