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Erosion, Abrasion, and Resorption

1-11. GENERAL

There are three conditions (besides dental caries) in which there is loss of tooth substance. They are erosion, abrasion and attrition, and resorption.

1-12. EROSION

Erosion is the chemical wearing away of the tooth structure by a chemical process that does not involve bacterial function. A common cause of erosion is chronic vomiting which results in enamel destruction through the action on teeth by stomach acids. Excess use of acidic carbonated beverages or acid citrus fruits may also be causative factors. Erosion is usually found on the external surface of the tooth on enamel structure adjacent to the cemento-enamel junction. It appears as various shapes cut into the surface at the neck of the tooth. The enamel and dentin are usually hard and shiny. In certain cases, the crowns may be severed from the roots. Considerable variation in appearance is normal between cases, but generally several teeth are involved, usually on the outer (labial) aspect of the crown.

1-13. ABRASION AND ATTRITION

Abrasion is considered to be an abnormal or excessive wearing away of tooth substance by a mechanical process. It can be seen clinically. In abrasion, one or more teeth may show the effects of wear. The wearing of the tooth substance may be caused by biting some foreign substance such as a pipe stem or a bobby pin, by faulty tooth brushing techniques, or by nervous biting habits. Attrition is the wearing away of tooth structure due to contact with an opposing tooth. It involves all the teeth with the cusps and contact points of all the teeth showing uniform wear. Abrasion and attrition differ in that attrition is considered a normal, gradual loss of tooth substance from the chewing of food and it involves all of the teeth, which will show uniform wear. If the loss of tooth substance is excessive, it is called abrasion. In both cases, the dentinal tubules may become calcified and secondary or irregular dentin may be deposited in the pulp immediately below them. Secondary cementum may be laid down about the roots.

1-14. RESORPTION

In resorption, there is the dissolving (removal) of body tissues by body fluids or cellular activity. Osteoclasts (cells that destroy bone) and cementoclasts (cells that destroy cementum) are the cells active in the resorption of bone and cementum. The condition is evident most often in the alveolar process and in the roots of teeth. Certain types of resorption may be considered normal. Other types may be the result of abnormal conditions. Healthy bone is constantly being remodeled. Resorption and deposition of bone is a normal physiological process and the principle that allows orthodontic movement of teeth. Stimulation of resorptive cellular activity through excessive mechanical or occlusal forces or through the normal shedding of the primary dentition is also within normal resorptive function. The effects of resorption can often be seen on a radiograph. Pathological resorption may be initiated through inflammatory stimulation or as the result of pressure exerted by developing neoplasms or cysts.

Normal Resorption. The roots of deciduous teeth are resorbed just before the eruption of the permanent teeth. There is also normal resorption of bone in edentulous areas where permanent teeth have been extracted. Healthy bone is constantly being remodeled. Resorption and deposition of bone is the basis for the treatment applied by the orthodontist who moves malposed teeth slowly into proper position. Resorption is also important in the repair of a fracture and the healing of a tooth socket.

Abnormal Resorption. There are other types of resorption that may not be considered normal. Resorption of the roots of permanent teeth may be the result of many factors involving disease and trauma. For example, systemic (endocrine) disturbances and some neoplasms are characterized by bone and root resorption. Impacted teeth may impose upon the roots of other teeth to cause areas of resorption.

External and Internal Resorption. Resorption of a tooth may develop externally or internally. Internal resorption is usually caused by inflammatory pulpal stimulation. External resorption may be caused by inflammatory stimulation of resorptive cells or through stimulation of resorptive cells associated with the pressure exerted by developing pathology or impacted teeth. This can cause resorption of tooth structure and surrounding alveolar bone. The cell responsible for the active resorptive process in bone is an osteoclast just as the cementoclast is for cementum. The osteoclast is developed from connective tissue cellular components in the pulp or area adjacent to an inflammatory stimulus outside the tooth.

David L. Heiserman, Editor

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Revised: June 06, 2015