Age changes of cementum
It is an abnormal thickening of the cementum. It may be generalized affecting all teeth such as in paget’s disease, or localized affecting one tooth. It may be diffuse through the whole root length, or limited to small area of the root.
Hypercementosis is termed cementum hypertrophy if the overgrowth improves the functional qualities of the cementum. Localized cementum hypertrophy is found in teeth that are exposed to great stress. Here an extension of cementum may be formed. This provides a larger surface area for the attaching fibers, thus assures firm anchorage of the tooth to the surrounding alveolar bone.
Hypercementosis is termed cementum hyperplasia if it is not correlated with increased function. It may be found in connection with non functional teeth (such as embedded teeth) and in this case is characterized by the reduction or absence of Sharpey’s fibers.
Extensive hyperplasia of cementum may be found in connection with chronic periapical infection.
Localized hyperplastic cementosis may occur on top of enamel drops, or develop around degenerated epithelial rest forming calcified knoblike projections called excementosis.
The permeability of cementum decreases gradually by age.
The permeability from the periodontal side is lost except in the most recently formed layer of cementum, while that from the dentine side remains only in the apical region.
3- Cementum Resorption and Repair
Cementum is more resistant to resorption than bone. However cementum resorption can occur after trauma or excessive occlusal forces or to small extent with orthodontic treatments.
After resorption ceases, the damage usually is repaired either by formation of acellular or cellular cementum and is demarcated by a reversal line observed by the light microscope.
If the repair establishes the former outline of the root surface it is called anatomic repair. However if a thin layer of cementum is deposited on the surface of a deep resorption, the root outline is not constructed. This is called functional repair.
3- Alterations in the physical, chemical, and structural characteristics
The alterations of cementum may occur due to periodontal pockets.
The surface of pathologically exposed cementum becomes hypermineralized because of the incorporation of calcium, phosphorus and fluoride.