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Radiographic Images: Errors and Techniques: How to ensure your radiographs make the grade every time.

As important members of the dental team, dental assistants are responsible for taking dental radiographs for patient treatment. Radiographic analysis is essential to comprehensive patient assessment and diagnosis. Non-diagnostic radiographs limit the ability to provide accurate information for patients' overall dental evaluation. Continued retaking of radiographs results in lost chair time and added cost to the dental practice, which can be frustrating to both patients and dental personnel. Retaking radiographs also increases the amount of radiation exposure to patients and assistants. Developing good radiographic skills can save time and help to reduce the amount of radiation exposure. While using RINN XCP and BAI beam alignment devices such as a Snap-A-Ray with digital radiography and film can help reduce radiographic errors, errors can still occur if the equipment is not used properly. Consider the following tips to reduce errors and avoid retaking radiographs.

Common Errors in Technique

Film placement: Film placement is important when checking for oral pathologies or abnormalities at the root surface. Film placement errors can occur on both digital and film when the receptor/film is placed improperly over the area to be examined. Errors can include cutting off the roots (Fig.1-A) or crowns (Fig.1-B) of teeth and/or missing the mesial or distal of the teeth under examination (Fig.1-B).

When taking a periapical radiograph, the top edge of the film should be slightly above the crowns of the teeth to avoid cutting off the roots of the teeth (1). Ensure that the patient is biting on the bite-block with his/her teeth and not with his/her lips; this will help to stabilize the bite-block. Have the patient smile to view that the patient is biting with his/her teeth and not the lips1. The design of some digital sensors may affect film placement. The smaller recording dimension may cut off the roots, to help avoid this problem slightly increase the vertical angulation of the x-ray cone to capture root surfaces (1).

Film placement errors for bitewings can occur when the film/sensor is placed too far back for a premolar film or too far forward for a molar film, cutting off the teeth under examination. Film placement errors can also occur when the bite-block is not placed evenly between the maxillary and mandibular arches.

To ensure proper placement for a premolar bitewing, place the film/sensor at the middle of the mandibular canine (1). For molar bitewings, place the film/sensor at the middle of the mandibular second premolar (1). To ensure that both maxillary and mandibular teeth are seen on a bitewing image, make sure the receptor is evenly placed in the bite-block, so that both jaws are seen equally. Film placement can be affected by patient comfort. Placing the film/sensor more towards the center of the mouth where the floor and palate are deeper will help with patient comfort (2).

Horizontal Angulation: Correct horizontal angulation is important when looking for interproximal decay. Overlap of the spaces in between the teeth can interfere with the ability to identify interproximal decay. Horizontal angulation is the positioning of the x-ray cone in a horizontal or side-to-side position (1). Incorrect horizontal angulation or overlapping occurs when the x-ray beam does not pass directly through the contact areas causing the images to shift and the interproximal areas overlap (2). Horizontal angulation errors can occur on both film and digital radiographs. The error can also occur with improper horizontal alignment of the receptor holding device (2).

To avoid this error, make sure the x-ray beam passes directly through the contact areas. When using the RINN XCP or other beam alignment devices, ensure that the device is placed parallel to the buccal/facial surfaces of teeth. A radiographic image with good horizontal angulation will allow the clinician to see black spacing between the teeth under examination.

Vertical Angulation (Elongation/Foreshortening): Improper vertical angulation can make it difficult to view the image of the teeth correctly. Vertical angulation is the positioning of the x-ray cone in a vertical or up-and-down position (1). Incorrect vertical angulation errors can cause either elongation or foreshortening.

Elongation errors occur when the x-ray cone is under-angulated or too shallow, causing the radiographic image to appear long and distorted.

To fix error, increase the vertical (up/down) angulation. Using a beam alignment device may help to reduce vertical angulation errors.

Foreshortening occurs when the x-ray cone is over-angulated or too steep, causing the radiographic image to appear short and blunted.

To correct the error, decrease the vertical (up/down) angulation. Using a beam alignment device may help to reduce vertical angulation errors.

Cone Cuts: Cone Cut errors occur when the x-ray cone is not centered over the film or sensor, creating a white unexposed image on the radiograph. This error can occur with digital or film.

If a beam alignment device is being used, make sure the receptor is in the center of the ring. Always check prior to exposing that the patient has not moved, causing the ring to no longer be aligned with the x-ray cone. Cone cuts are common on bitewing films when it is hard to see the film. Placing the tab at the anterior edge of the film and moving the cone slightly ahead of the tab can center the film in the middle of the x-ray cone and help to reduce the cone cut error.

Reversed Films: Reversed films occur when the receptor/film is placed in the mouth backwards. Reversed films can occur on both film and sensor. On film, the image will appear lighter and the pattern of the lead foil will leave an image on the film. With digital sensors, the placement of the sensor in a backwards position does not allow the radiation to interact with the sensor, creating a black image on the screen (1).

When using film, make sure the white side of the film is outward towards the clinician. When using digital sensors, make sure the front side, which has the company's name on it, is facing the teeth.

Creasing: Creasing can occur with either film or digital phosphor plates. The errors occur when the receptor is manipulated for patient comfort. The result is a radiolucent line across the radiographic image.

To prevent this error, do not over-manipulate the receptor in the patient's mouth. Bending the phosphor plate can damage the plate.

Improving Your Clinician Skills

The ability of dental assistants to take quality radiographs is a great asset to the dental practice, saving time and cost and creating a less stressful work environment. Improving the quality of dental images can reduce the amount of radiation exposure to patients and assistants. Exposing radiographs is a learned skill that is developed with time and practice. Comprehending and utilizing correct radiographic techniques will help to improve the dental assistant's clinical skills, adding to their effectiveness as a member of the dental team.


(1.) lannucci J, Howerton LJ. Dental Radiography-E-Book: Principles and Techniques.: Elsevier Health Sciences; 2016.

(2.) Williamson GF. Intraoral Radiography: Principles, Techniques and Error Correction.

By Audra E. Haynes, RDH, MPH

Audra E Haynes, RDH, MPH, is a professor at New York City College of Technology in Brooklyn, NY. Her teaching responsibilities include radiology and clinical instruction. A former dental assistant, Haynes is also a New York State Board member and dental hygiene licensing examiner. Reach her at

Crowns cut off     Place films slightly above crowns
Roots cut off      1. Ensure patient is biting on bite-block
                   with teeth
                   2. Increase vertical angulation of sensors
Premolars cut off  Place film/sensor at middle of mandibular
in bitewing        canine
Molars cut off in  Place receptor at middle 2nd premolar
Teeth not evenly   Place bite-block equally between both jaws
seen in bitewing
Overlapping        Beam alignment device is parallel to facial
Stretched image    1. Increase vertical (up/down) angulation
                   2. Use a beam alignment device
Blunted image      1. Decrease vertical (up/down) angulation 2. Use a
                   beam alignment device
Cone Cuts          1. Receptor is in the center of the ring
                   2. Tab at the edge of the film, cone just
                   slightly ahead of the tab, center film in
                   the middle of the cone
Reversed Film      1. White side of the film is facing the teeth
                   2. Digital sensor, the company name is
                   facing the teeth
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Author:Haynes, Audra E.
Publication:The Dental Assistant
Date:Jul 1, 2018
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