Good Morning

Bone loss and Patterns of Bone Destruction

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.

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.

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

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

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.

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

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

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

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

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

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

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

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

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

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

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

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

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

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.

BONE DESTRUCTION PATTERNS IN PERIODONTAL DISEASE

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

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

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

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

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

Three Walled Defect – Intrabony defect One Walled Defect - Hemiseptum

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

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.

Osseous Craters

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

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.

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

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.

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.

GLICKMAN GRADING GRADE 1 GRADE 2 GRADE 2

GRADE 3 GRADE 3 GRADE 4 GRADE 4

Grade 4 Furcation

THANK YOU…