Bite-Wing Technique Study Notes

Bite-Wing Technique
Key Terms

  • The Bite-Wing Technique is a specialized procedure used to take X-ray images of the surfaces between your teeth.

    • This technique is very helpful for monitoring how dental caries (cavities) are developing, checking the condition of any existing dental fillings or restorations, and observing the bone levels specifically between your teeth.

    • This method is also commonly known as the interproximal technique.

Purpose and Use

  • The bite-wing X-ray image allows dentists to examine both the upper (maxillary) and lower (mandibular) teeth at the same time.

  • Its main purpose is to help monitor your dental health and find any problems with the surfaces where your teeth touch each other.

Appearance of Images

  • Opened Contact Areas: When the image shows clear spaces between the teeth, it means the X-ray was taken with the correct horizontal angulation.

  • Overlapped Contact Areas: If the images show that your teeth appear to be overlapping, it means the horizontal angulation was incorrect, and this makes the image unclear and difficult to read.

Basic Principles of the Bite-Wing Technique

  • The X-ray sensor (receptor) is placed inside your mouth, positioned closely and parallel to the chewing surfaces (crowns) of both your upper and lower teeth.

  • To keep the sensor steady, the patient either bites down on a small tab attached to the sensor (a bite-wing tab) or uses a special device called a beam alignment device.

  • The central x-ray beam is carefully pointed so it passes directly through the contact areas where your teeth touch each other, using a vertical angle of .+10°..+10°..

Receptor Stabilization Methods

  1. Bite-Wing Tab: This is the recommended way to hold the X-ray sensor steady while exposures are being taken.

  2. Beam Alignment Device: This is an alternative tool that helps guide and position the sensor correctly during the X-ray procedure.

Receptor Sizes for Bite-Wing Technique

  • Size 0: This is the smallest size and is used for taking X-rays of the back teeth in young children who still have their primary teeth.

  • Size 2: This size is typically used for the back teeth of older children and adults; it can be positioned either horizontally (side-to-side) or vertically (up-and-down).

  • Size 3: This size is generally not recommended for adult patients because it is too wide and can lead to inaccurate images.

Horizontal Angulation

  • Correct Horizontal Angulation: This occurs when the central X-ray beam is aimed directly through the contact areas where your teeth touch and is also perpendicular (at a right angle) to the curve of your dental arch.

  • Incorrect Horizontal Angulation: If the X-ray beam is angled incorrectly, it will cause the tooth contacts to appear overlapped on the image, which means important diagnostic information will be lost.

Vertical Angulation

  • Positive Vertical Angulation: This is when the X-ray machine's cone (Position Indicating Device or PID) is placed above the chewing plane and points downwards towards your teeth.

  • Negative Vertical Angulation: This is when the PID is placed below the chewing plane and points upwards towards your teeth.

  • Recommended Vertical Angulation: For all bite-wing X-rays taken with a bite-wing tab, a .+10°..+10°. angle is suggested for the most accurate results.

  • Consequences of Incorrect Vertical Angulation:

    • If the vertical angle is not correct, it can make it hard to see the lower jaw (mandible) clearly.

    • If the vertical angle is too much, it can distort the images of the upper jaw (maxillary) teeth.

Basic Rules for the Bite-Wing Technique

  1. Receptor Placement: The X-ray sensor must be placed so it fully covers all the specific teeth that need to be examined.

  2. Receptor Position: The sensor should be positioned parallel to the chewing surfaces (crowns) of both the upper and lower teeth.

  3. Vertical Angulation: When using a bite-tab, the central X-ray beam must be directed at a .+10°..+10°. angle.

  4. Horizontal Angulation: When using a bite-tab, the central X-ray beam must be directed precisely through the contact areas where the teeth touch.

  5. Receptor Exposure: The X-ray beam must be perfectly centered on the sensor to ensure the entire image area is exposed and to prevent an error called cone cutting (where part of the image is cut off).

Patient Preparations

  • It is important to clearly explain the X-ray procedure to the patient so they understand what will happen.

  • The patient should be sitting upright in the dental chair, and the headrest should be adjusted properly to support their head.

  • A lead apron, along with a thyroid collar, must be securely placed on the patient to protect them from unnecessary radiation.

  • Before imaging, instruct the patient to remove any eyeglasses and any objects from their mouth, such as partial dentures or retainers.

Equipment Preparations

  1. Ensure that the correct X-ray exposure settings (factors) are entered into the machine.

  2. If a beam alignment device is being used, open its sterilized package and assemble it correctly.

  3. If using bite-wing tabs, make sure to attach the tab properly to the white side of the X-ray sensor.

Exposure Sequence for Receptor Placements

  • Typically, two bite-wing X-ray sensors are used on each side of the mouth:

    • One X-ray image is taken for the premolar (front back) teeth and another for the molar (back) teeth on each side.

  • If a patient has missing back teeth, sometimes one bite-wing sensor per side might be enough.

  • For a complete mouth series (CMS) of X-rays:

    • First, all X-rays of the front (anterior) teeth (called periapical receptors) are exposed.

    • Next, all X-rays of the back (posterior) teeth (periapical receptors) are exposed.

    • Finally, the bite-wing X-rays are taken to complete the series.

  • If only bite-wing X-rays are being taken:

    • Start by exposing the premolar bite-wing sensor, followed by the molar bite-wing sensor on each side of the mouth.

Receptor Placement for Bite-Wing Images

  • The exact way the sensor is placed depends on the unique shape of the patient's teeth and surrounding oral structures.

  • For film-based sensors, the white side of the film must always face towards the teeth being imaged.

  • In a series of posterior bite-wing X-rays, the sensors are typically placed horizontally. They are centered over the area to be examined, and the patient is instructed to bite down slowly on the tab or block to stabilize the sensor.

Vertical Bite-Wings

  • These specific bite-wing X-rays are used to check the level of the bone supporting the teeth (alveolar bone) in patients who are being assessed for periodontal (gum) disease.

  • For vertical bite-wings, the long part of the sensor is positioned in an up-and-down (vertical) direction.

  • A setup using 7 sensors effectively covers the canine (pointy), midline (front center), premolar, and molar areas:

    • This can involve 3 anterior (front) and 4 posterior (back) sensors, all using size 2 sensors, or a combination where size 1 sensors are used for the anterior areas.

Modifications in the Bite-Wing Technique

  1. For Edentulous Spaces (Missing Teeth): If a patient has a missing tooth in the area where the bite-wing sensor needs to be placed, a cotton roll should be put in that space to help support the bite-wing tab or beam alignment device.

  2. For Bony Growths (Tori): If there are bony growths (called tori) in the mouth, make sure the X-ray sensor is positioned between the torus and the tongue. This helps to get a clear image without the growth blocking the view.

Illustration of Technique Errors in Angulation

  • Errors in horizontal angulation can result in images where the teeth are projected incorrectly from either the front-to-back (mesiodistal) or back-to-front (distomesial) aspects, leading to overlapping.

  • It is critical to correct these positioning errors to achieve accurate and useful images.