Intraoral Radiographs

Paralleling Technique – Keys to Success

Sensor holder – mesial-distal position

  • Centered on contact to be opened (see “Image-specific contacts to open” below)

Sensor – intraoral position (to ensure parallel to root)

  • Maxilla – must be near the center of the palate (i.e., NOT touching the teeth)
  • Mandible – as far medial towards the tongue that is tolerable by the patient, especially in the presence of tori

X-ray beam – horizontal angulation

  • In line with embrasure angle of contact to be opened (see “Overlapped contacts” below)

Position Indicating Device (PID) (i.e., Collimator or “Cone”)

  • Edge is parallel to sensor holder arm and end is flush with ring (see “Armamentarium”)

Foreshortening and Elongation – Errors in Paralleling Technique

  • Yellow line = correct Vertical angulation (perpendicularly intersects long axis of the tooth)
  • Note: Positive (+) angulation indicates downward trajectory
  • Note: Negative (-) angulation indicates upward trajectory
Quality Assurance


  • Include apices and bone 2mm beyond


  • Include 2mm beyond alveolar crest

Image-specific contacts to open

  • Yellow = centralized contact – a function of proper x-ray beam horizontal angulation
  • Pink = distal canine contacts – a function of proper mesial-distal positioning of the sensor
  • Note: mirror contacts to contralateral side as needed

What defines an open contact?

  • Caries can be reliably diagnosed if the overlap is less than ½ the thickness of enamel, which is the case for the 2nd and 3rd molar contact in the molar bitewing below

Overlapped contacts – Errors in Horizontal Angulation

  • Horizontal angulation is the mesial-distal angulation of the x-ray beam (blue arrows)
  • Contacts will be opened if the blue arrows mimic the green lines – buccolingual embrasures that as you move more distally along the arch, generally become more distally angled

  • Yellow circles are contacts to open in a full mouth series
  • Note 1: These are idealized contacts – real life is not so easy, so one must look and adjust accordingly
  • Note 2:  Big assumption is the incoming beam is perpendicularly hitting the sensor located lingual to the teeth – a feat made easier if a sensor holder is used properly (see Paralleling Technique section)

Sensor Size

  • Size 1 sensors are recommended for the anterior periapicals images due to narrower space availability in the anterior palate and floor of the mouth

Sensor Holder

  • Consists of holder, arm, bite tab, and ring
  • Ensures paralleling of sensor and ring
  • Note:  Paralleling Technique not guaranteed unless the sensor is also placed parallel to the long axis of the tooth (see “Paralleling Technique” above)


  • Identify root morphology / pathology
  • Endodontics


  • Interproximal caries and calculus
  • Restoration overhangs
  • Identify periodontal bone loss
  • Confirm crown seating

Vertical Bitewings

  • Assess previously identified periodontal bone loss
  • Confirm implant crown seating

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