Overview
Today's lecture covers trauma from occlusion (TFO)—its definition, classification, effects on periodontium, clinical and radiographic signs, underlying theories, and histopathology.
Occlusion and Occlusal Forces
- Occlusion is the contact relationship between maxillary and mandibular teeth.
- Occlusal (biting) forces are transmitted first to the alveolar bone, then to the basal bone.
- The periodontium has adaptive capacity that allows it to withstand normal occlusal forces.
Adaptive Capacity of Periodontium
- Increased force magnitude causes PDL (periodontal ligament) thickening and increased PDL fibers and alveolar bone density.
- Change in force direction leads to PDL fiber rearrangement.
- Constant forces cause more injury and bone resorption than intermittent forces.
- Increased force frequency leads to more periodontium destruction.
Trauma from Occlusion (TFO)
- TFO occurs when occlusal forces exceed periodontium adaptive capacity, causing tissue injury.
- Synonyms: occlusal trauma, traumatogenic occlusion, periodontal trauma, overload, traumatizing occlusion.
Classification of Trauma from Occlusion
- By onset/duration:
- Acute TFO—abrupt change (e.g., biting on hard object, faulty restoration).
- Chronic TFO—gradual change (e.g., tooth wear, drifting, parafunction).
- By cause:
- Primary TFO—excess forces on healthy periodontium (normal height).
- Secondary TFO—normal or mild forces on compromised periodontium (attachment loss).
- Combined TFO—excess forces on compromised periodontium.
Theories on TFO in Periodontal Disease
- Glickman's Concept: excessive occlusal forces change the pathway of inflammation, leading to angular bone defects (zone of co-destruction) vs. horizontal defects (zone of irritation, only plaque).
- Waerhaug's Concept: angular defects can occur with plaque alone, without TFO; refutes Glickman.
Signs and Symptoms of TFO
- Clinical: tooth mobility, pain on chewing/percussion, positive fremitus test, wear facets, tooth migration, chipped/fractured tooth, thermal sensitivity.
- Radiographic: widened PDL, thickened lamina dura, vertical/angular bone loss, furcation radiolucency, no pocket formation.
Histopathologic Changes in TFO
- Stage of Injury: excessive forces cause PDL changes, bone resorption, hemorrhage, and hyalinization/necrosis.
- Stage of Repair: buttressing bone formation (central or peripheral/lipping) compensates for lost bone.
- Stage of Remodeling: thickened PDL, increased vascularity, angular defects, and tooth mobility result from adaptation.
Key Terms & Definitions
- Occlusion — contact relationship between the upper and lower teeth.
- Periodontium — supporting tissue of teeth (PDL, alveolar bone, cementum, gingiva).
- PDL (Periodontal Ligament) — connective tissue between tooth root and alveolar bone.
- Buttressing Bone Formation — reinforcement of bone in response to stress/injury.
- Fremitus Test — detects tooth vibration from occlusal forces.
Action Items / Next Steps
- Review pathologic tooth migration in the second part of the lecture.