• Acid Etch
  • A weak acid which is applied to the teeth to prepare the teeth for brackets
• Alginate
  • A flavoured plaster-like compound used to take impressions
• Angles Classification
  • A description used to classify the different types of malocclusion
• Ankylosis
  • Abnormal immobility of a tooth, where it becomes directly attached to the bone.
• Anodontia
  • Congenital absence of all the teeth (c.f. hypodontia)
• Anterior
  • Situated in the front, a term commonly used to denote the incisor and canine teeth
• Apex
  • The top of the tooth root
• Appliance
  • A fixed or removable device which the orthodontist uses to change the position of teeth or jaws
• Arch
  • The ensemble of teeth in either jaw in a horseshoe shape
• Arch
  • The ensemble of teeth in either jaw in a horseshoe shape
• Arch Wire
  • A wire which is attached to brackets to move teeth to their correct position
• Articulator
  • A device to hold models of the teeth which allows the teeth and their position to be studied
• Attrition
  • Wearing away of the biting surfaces of the teeth