National Board Dental Hygiene Examination (NBDHE) Dental Hygienist Practice Test

What is the primary cause of abfraction in teeth?

1. Enamel erosion

2. Mechanical stress

3. Microbial activity

4. Fluoride deficiency

The correct answer is: Mechanical stress

The primary cause of abfraction in teeth is mechanical stress. Abfraction is the loss of tooth structure at the cervical area of the tooth, which is often described as a wedge-shaped defect. This condition arises from the flexing of teeth during normal function (such as biting and chewing), particularly when forces are applied to a tooth in ways that exceed its structural integrity. Mechanical stress can lead to microfractures in the enamel and dentin, resulting in the characteristic loss of tooth structure associated with abfraction. This process is influenced by various factors, such as occlusal forces, tooth grinding (bruxism), and malocclusion, which can amplify the stress experienced by the teeth. While enamel erosion, microbial activity, and fluoride deficiency can all affect dental health, they are not the primary causes of abfraction. Enamel erosion involves the chemical wearing away of tooth structure due to acid exposure, microbial activity is related to cavities and periodontal disease, and fluoride deficiency can contribute to enamel weakness but does not directly cause the mechanical stress leading to abfraction. Understanding the mechanical aspect emphasizes the importance of managing occlusal forces and promoting healthy bite alignment to prevent this type of tooth structure loss.