Dental

• Teeth in the maxillae and mandible

  • 16 in the maxillae
  • 16 in the mandible
• Deciduous and permanent teeth

  • 20 deciduous
  • 32 permanent
• Parts of a tooth

  • Crown
  • Neck
  • Root
• Structure of a tooth

  • Pulp cavity
  • Dentine
  • Enamel
  • Cement
  • Apical foramen
• Classification of permanent teeth

  • Molar (12)
  • Premolar (8)
  • Canine (4)
  • Incisor (8)
• Crown


  The exposed part, visible in the mouth
• Cusps


  Small rounded prominences on the surfaces of the premolar and molar teeth
• Neck


  The constricted part where the crown and root meet
• Root


  The smaller tapered end, located in the alveolar process of the maxilla or the alveolar part of the mandible
• Lingual surface


  The aspect facing the tongue
• Labial or buccal surface


  The outer aspect facing the lip or cheek
• Pulp cavity


  The central cavity within a tooth extending from the crown down the root
• Dentine


  Modified bone that surrounds the pulp cavity in both the crown and root
• Enamel


  A thin covering that forms an outer coat for the crown
• Cement


  A layer of modified bone that covers the dentine of the root
• Apical foramen


  A minute opening in the tip of the root by which a nerve and an artery enter, and a vein leaves the pulp cavity
• Peridental membrane


  A layer of fibrous tissue that surrounds the root of each tooth and attaches it to the wall of the socket in which the tooth lies
• Occlusion


  The position of the upper and lower teeth in relation to each other when the mouth is closed
• Malocclusion


  The cusps and grooves do not fit into each other, or in some instances opposing teeth may not touch each other
• Function of incisors


  To bite off mouthfuls of food
• Function of premolars and molars


  To grind and masticate food
• The object is to break food into small pieces so that the digestive juices may come into intimate contact with the food particles when it reaches the digestive organs
• Alveolar process


  That portion of the maxilla or mandible that surrounds and supports the teeth, composed of the lamina dura and the supporting bone
• Lamina dura


  The hard, cortical bone that lines the alveolus (the tooth socket), appearing as a thin radiopaque (white) border outlining the shape of the alveolus on radiographs
• Periodontal Ligament Space


  Attaches the teeth to the lamina dura, made up of soft tissues and not imaged on a radiograph
• Nutrient canals


  Thin radiolucent lines of fairly uniform width that sometimes exhibit radiopaque borders, containing blood vessels and nerves that supply the teeth, bone, and gingivae
• Tooth structures

  Enamel, dentin, cementum, and pulp
• Enamel, the hardest body structure, covers the crown and is very radiopaque. The underlying dentin is not as dense and appears less radiopaque. The cementum that covers the roots is even less dense. The tooth pulp that occupies the pulp chamber and the root canals is the only noncalcified tooth tissue and appears radiolucent.
• Young children have 20 primary teeth that are gradually lost as they grow older. There are 32 permanent teeth, including all four of the third molars (wisdom teeth).
• Occasionally, teeth form but are unable to erupt (impacted teeth). Some people have one or more extra teeth (supernumerary teeth). Another deviation is the congenital absence of certain teeth (anodontia). These conditions occur so frequently that, although not normal, they are not considered pathologic.
• Dental X-ray Machine Components


  • Control panel
  • Extension arm or bracket
  • Tube head
• Control Panel


  Contains the regulating devices
• Major controls on dental x-ray machines

  • Line switch
  • Milliampere selector
  • Kilovoltage selector
  • Timer
  • Exposure button
• Line switch


  Toggles the electrical outlet on or off
• Milliampere (mA) selector


  Measures the amount of current passing through the wires of the circuit
• Kilovolt Peak (kVp) selector


  Measures the difference in potential or voltage across the x-ray tube
• Timer


  Regulates the duration of the interval that the current will pass through the x-ray tube
• Exposure button


  Activates the x-ray production process, with a "dead-man" switch that automatically terminates the exposure
• Extension arm


  A support from which the tube housing is suspended, allowing for moving and positioning the tube head
• Tube head (tube housing)


  A tightly sealed heavy metal, lead-lined housing that contains the dental x-ray tube, insulating oil, and step-up and step-down transformers