1. Good Morning

2. Bone loss and Patterns of Bone Destruction

3. Introduction
The height and density of the alveolar bone are normally maintained by an equilibrium
regulated by local and systemic influences between bone formation and bone resorption.

4. ETIOLOGY OF BONE LOSS EXTENSION OF INFLAMMATION:
The extension of inflammation to the supporting structures of a tooth may be modified by -
the pathogenic potential of plaque
the resistance of the host
The pathway of the spread of inflammation is critical because it affects the pattern of bone destruction in periodontal disease.

5. PATHWAY OF INFLAMMATION
A – Interproximally
1 – from gingiva to bone
2 – from bone to Pdl
3 – from gingiva to Pdl directly
B – Facially & Lingually
1 – from gingiva to outer periosteum
2 – from periosteum to bone
3 – from gingiva to Pdl directly

6. MECHANISMS OF BONE DESTRUCTION
Pathways by which products in plaque absorbed by periodontal tissues could cause alveolar bone loss are -
1) Products from plaque could stimulate bone progenitor cells in the periodontium to differentiate into osteoclasts, which resorb alveolar bone.
2) Absorbable products from plaque like hydrolytic enzymes destroy alveolar bone

7. 3) Absorbable products from plaque could stimulate cells within the gingiva to release mediators, which in turn could trigger bone progenitor cells to differentiate into bone resorbing osteoclasts.
4) Gingival cells could release agents, which destroy bone by direct chemical action.

8. PERIODS OF DESTRUCTION
Periodontal destruction occurs in an episodic, intermittent fashion, with periods of inactivity.
The destructive periods result in loss of collagen and alveolar bone with deepening of the periodontal pocket.
Periods of exacerbation - increase of the loose, unattached, motile, gram negative, anaerobic pocket flora
Periods of remission - formation of a dense, unattached, non-motile, gram positive flora

9. Bone Formation in Periodontal Disease
Areas of bone formation are seen adjacent to sites of active bone resorption
New bone formation retards the rate of bone loss
Thus, periods of remission and periods of exacerbation are seen

10. Bone Destruction caused due to Trauma from Occlusion
When occlusal forces exceed the adaptive capacity of the tissue, tissue injury results. The resultant injury is termed trauma from occlusion.
An occlusion that produces such injury is called a traumatic occlusion.
Trauma from occlusion causes –
widening of the marginal periodontal ligament space narrowing of the interproximal alveolar bone shelf-like thickening of the alveolar margin

11. 1) Increased width of the periodontal space
Radiographic signs of trauma from occlusion may include the following -
1) Increased width of the periodontal space
2) A “vertical” destruction of the interdental septum
3) Radiolucency of the alveolar bone
4) Root resorption

12. Bone Destruction caused by Systemic Diseases
Systemeic influence on the response of alveolar bone is termed as – Bone factor in Periodontal Disease
The presence of a systemic condition influences the severity of periodontal destruction

13. OSTEOPOROSIS :
Osteoporosis results in loss of bone mineral content and structural bone changes
Risk factors for periodontitis and Osteoporosis are –
Ageing
Smoking
Diseases
Medications that interfere with healing

14. Other Skeletal Disorders that cause Periodontal Bone loss are –
Hyperparathyroidism
Leukemia

15. Factors Determining Bone Morphology in Periodontal Disease
Normal variations in Alveolar Bone Exostoses Trauma from Occlusion Buttressing Bone Formation Food Impaction Aggressive Periodontitis

16. Normal variations in Alveolar Bone -
Thickness, width & crestal angulation of the interdental septa
Thickness of facial and lingual alveolar plates
Presence of fenestrations & dehiscences
Alignment of teeth
Root & root trunk anatomy
Position of root
Proximity with adjacent tooth surface

17. Exostoses: Are outgrowths of bone of varied size and shape.
They can occur as -
small nodules
large nodules
sharp ridges
spike-like projections

18. Trauma from Occlusion (TFO) –
TFO is a factor in determining the dimension & shape of bone deformities
It may cause – thickening of cervical margin of bone
Change in morphology of bone – buttressing bone formation

19. Buttressing Bone formation (Lipping):
Bone formation sometimes occurs in an attempt to buttress bony trabeculae weakened by resorption.
Central Buttressing Bone Formation - when bone formation occurs within the jaw
Peripheral Buttressing Bone Formation - When bone formation occurs on the external surface
Lipping – bulging of bone contour in peripheral buttressing bone formation

20. Food Impaction –
Proximal contact between teeth is a very important factor
Open contact – Food Lodgement
Closed (tight) contact – Food Impaction
Interdental bone defects occur when proximal contact is abnormal
Pressure from food impaction – inverted bone arhitecture

21. Aggressive Periodontitis -
Vertical or Angular bone loss is seen around the 1st molars
Include an “arc-shaped’ loss of alveolar bone extending from the distal surface of the second premolar to the mesial surface of the second molar.

22. BONE DESTRUCTION PATTERNS IN PERIODONTAL DISEASE

23. Bone Destruction Patterns Are -
Horizontal bone loss
Vertical or Angular defects
Osseous craters
Bulbous bone contours
Reversed architecture
Ledges
Furcation involvement

24. Horizontal Bone Loss :
This is the most common pattern of bone loss in periodontal disease
The bone is reduced in height
The interdental septa and facial and lingual plates are affected

25. Vertical Bone Loss or Angular Defects:
Occur in an oblique direction, leaving a hollowed out trough in the bone along side the root

26. Angular defects are classified as follows depending on the number of osseous walls present:
1)Three wall bony defects - are bordered by three osseous surfaces.
2)Two walls bony defects - (interdental craters) are bordered by two osseous surfaces.
3)One wall bony defects - one osseous surface present

27. Vertical Bone Loss or Angular Defects:
A – Three wall defect 1 – Distal wall 2 – Lingual 3 - Facial
B – Two wall defect
1 – Distal wall
2 – Lingual
C – One wall defect
1 – Distal wall

28. Three Walled Defect – Intrabony defect
One Walled Defect - Hemiseptum

29. Combined Osseous Defect –
Here the facial wall is half the height of the distal wall (1) and lingual wall(2)
This is an osseous defect with 3 walls in the apical half & 2 walls in the occlusal half

30. Osseous Craters:
Concavities in the crest of the interdental bone confined within the facial and lingual walls.
More common in posterior teeth
Reasons for the high frequency of interdental craters -
- The interdental area collects plaque and is difficult to clean.
- The shape of the interdental septum in lower molars may favour crater formation.

31. Osseous Craters

32. Bulbous Bone Contours:
These are bony enlargements caused by exostoses, adaptation to function, or buttressing bone formation.

33. Reversed Architecture:
Produced by loss of interdental bone, including the facial and/or lingual plates, without concomitant loss of radicular bone, thereby reversing the normal architecture.
More common in the maxilla.

34. Ledges:
Ledges are plateau-like bone margins caused by resorption of thickened bony plates.

35. Furcation Involvement:
Refers to the invasion of the bifurcation and trifurcation of multirooted teeth by periodontal disease.
The mandibular first molars are the most common sites.

36. Grade I - is incipient bone loss. Radiographic changes not found.
Furcation involvement has been classified according to the amount of tissue destruction –
Grade I - is incipient bone loss. Radiographic changes not found.
Grade II - is partial bone loss (cul-de-sac)
Grade III - is total bone loss with through-and-through opening of the furcation, but no gingival recession
Grade IV - is similar to grade III, but with gingival recession exposing the furcation to view.

37. GLICKMAN GRADING
GRADE 1
GRADE 2
GRADE 2

38. GRADE 3
GRADE 3
GRADE 4
GRADE 4

39. Grade 4 Furcation

40. THANK YOU…