Perio II 0929

• Static occlusion: contacts between teeth when the mandible is closed and stationary.
• Dynamic occlusion: contacts between teeth when the mandible is moving relative to the maxilla.

• PDL
• Cementum
• Bone

• Principal fibers: alveolar crest, horizontal, oblique, apical, inter-radicular; collagen - Sharpey's fibers; Can't handle lateral/horizontal forces
• Cellular elements: help repair after injuries
• - Connective tissue cells
• - Epithelial rest cells
• - Immune system cells
• - Neurovascular elements
• Ground substance

• Acellular and cellular
• Intrinsic fibers - formed by cementoblasts
• Extrinsic fibers - Sharpey's fibers, embedded portion of the principal fibers of PDL; formed by fibroblast
• Ground substance

• Organic Components / Cells:
• - Osteoblasts
• - Osteoclasts
• - Fibroblasts
• - Blood vessels
• - Nerve tissue
• - Sharpey fibers
• Inorganic Components
• - Mineral salts

• compact/cortical bone (where Sharpey's fibers insert) lining tooth socket
• radiographic term
• Alveolar bone proper

• Alveolar bone undergoes constant remodeling in response to external forces.
• The thickness of the periodontal ligament is maintained by the amount of functional forces - more work, more activated, thicker; no force, thinner.

The effects of occlusal forces on the periodontium is influenced by the magnitude, direction, duration and frequency of force.

• Widening pdl space
• Increase pdl fibers number and width
• Increase alveolar bone density

• principal fibers of pdl best accommodate forces along the long axis of the tooth
• Lateral (horizontal) forces and torque (rotational) forces are more likely to injure the periodontium by reorienting stresses and strains within the periodontium

• Constant pressure vs. intermittent forces
• More frequent application of an intermittent force
• Acute vs. Chronic

• The lesion may occur in conjunction with or independent of inflammatory periodontal diseases, and they may be treated separately.
• Occlusal traumatism may occur in an intact periodontium that has been reduced by inflammatory periodontal disease.

• Tooth mobility (stable - adaptation; increasing mobility - current or progressing trauma)
• Tooth migration or shift in jaw movement
• Tooth pain on chewing or sensitivity to percussion
• Radiographic changes:
• - Widening of PDL space
• - Disruption of lamina dura
• - Radiolucencies in furcation area or apex of vital teeth
• - Root resorption
• Tenderness of muscles of mastication or signs and symptoms of TMD
• Presence of wear facets
• Chipped enamel or crown/root fracture
• Fremitus

• 1. Alterations in occlusal forces due to habits such as clenching, bruxism, nail biting, cheek biting or occlusal discrepancies (Primary occlusal trauma)
• 2. Reduced capacity of the periodontium to withstand occlusal forces as with Periodontal Disease (Secondary occlusal trauma)
• 3. Combination of 1 and 2

• • Restoration in hyperocclusion
• • Restoration that creates excessive forces on abutment teeth and opposing teeth
• • Orthodontic movement of teeth into functionally unacceptable positions (occlusal discrepancies)