16 The Bitewing Examination

Objectives Define the key words. Match the bitewing examination with two ideal uses. Describe the bitewing radiographic technique. List the four sizes of image receptors that can be used for bitewing surveys explaining advantages and disadvantages of each size.

Objectives Differentiate between horizontal and vertical bitewing radiographs Identify the type, size, and number of image receptors best suited for a child bitewing survey. Explain the effect of horizontal angulation on the resultant bitewing image. Identify positive and negative vertical angulations.

Objectives State the recommended vertical angulation for bitewing exposures. Compare methods used for holding the bitewing image receptor in position. Describe the image receptor placement, horizontal and vertical angulation, and point of entry for horizontal and vertical posterior bitewing examinations.

Objectives Describe the image receptor placement, horizontal and vertical angulation, and point of entry for a vertical anterior bitewing examination.

Key Words Bitetab Bitewing radiograph Contact points Embrasures External aiming device Film loop

Key Words Horizontal angulation Horizontal bitewing radiograph Interproximal radiograph Mean tangent Overlap

Key Words Point of entry Proximal surface Vertical angulation Vertical bitewing radiograph

Introduction Bitewing radiographs are probably the most frequently performed intraoral dental radiographic technique. Bitewing radiographs image the crowns and alveolar bone of both the maxillary and mandibular teeth on a single radiograph.

Figure 16-1 Bitewing tabs and loops Figure 16-1 Bitewing tabs and loops. (A) Loop tabs; (B) Stick-on tabs; (C) Size #3 film packet with manufacturer-attached tab.

Figure 16-2 Bitewing loop for digital sensor.

Figure 16-3 (A) Horizontal and (B) vertical bitewing radiographs Figure 16-3 (A) Horizontal and (B) vertical bitewing radiographs. Bitewing radiographs are ideal at imaging the interproximal areas of the teeth to show caries and alveolar bone crests. Note the increased coverage of the alveolar bone imaged on the vertical bitewing radiograph.

Figure 16-4 Bitewing placement Figure 16-4 Bitewing placement. The bitewing image receptor placement, slightly angled to take advantage of the height of the midline of the palate when the patient occludes, is such that the coronal portion of both the maxillary and the mandibular teeth will be recorded on the image. The close relationship between the teeth and the image receptor and the ideal angle of the x-ray beam allow bitewings to accurately image caries and alveolar bone crests.

TABLE 16-1 Suggested Image Receptor Size and Number to Use for Bitewing Radiographs

Figure 16-5 Comparison of size #2 and size #3 image receptors Figure 16-5 Comparison of size #2 and size #3 image receptors. (A) Size #2 has a shorter horizontal dimension, taller vertical dimension. (B) Size #3 has a longer horizontal dimension, shorter vertical dimension.

Figure 16-6 Horizontal and vertical bitewing series Figure 16-6 Horizontal and vertical bitewing series. (A) Set of two horizontal posterior bitewing radiographs. (B) Set of four horizontal posterior bitewing radiographs. (C) Set of seven vertical bitewing radiographs, including posterior and anterior images.

Figure 16-7 Two stick-on bitetabs lengthen the holder for use in the anterior region.

Figure 16-8 Occlusal relationships Figure 16-8 Occlusal relationships. (A) Class I occlusion demonstrating that the mandibular canine and second premolar (shaded) are located further forward in the oral cavity. (B) Class II occlusion demonstrating that the maxillary canine and second premolar (shaded) are located further forward in the oral cavity. (C) Class III occlusion demonstrating that the mandibular canine and second premolar (shaded) are located further forward in the oral cavity.

Figure 16-9 Tilted image. The slanted occlusal plane observed on this radiograph resulted from a failure to place the image receptor far enough lingually to avoid being pushed down by the palate when the patient occluded onto the bitetab.

TABLE 16-2 Recommended Sequence for Exposing Bitewing Radiographs

Figure 16-10 Bitewing placement using a stick-on tab Figure 16-10 Bitewing placement using a stick-on tab. (A) Insert the image receptor completely into the patient’s mouth. (B) Rotate until the image receptor is in a vertical position. Inserting in this manner allows the image receptor to move the tongue out of the way. (C) Using the index finger of one hand, hold the bitetab firmly against the occlusal surface of the mandibular teeth while the index finger of the other hand angles the top edge of the image receptor into the midline of the palate. (D) Instruct the patient to close so that the teeth occlude normally. Failure to hold the tab firmly may lead to a drift lingually and distally and increase the possibility that the tongue will move the image receptor out of the correct position.

Figure 16-11 Bitewing image receptor holder with metal positioning arm and plastic external aiming ring. (Courtesy of Dentsply Rinn.)

Figure 16-12 Holder comparison Figure 16-12 Holder comparison. (A) Bitewing radiograph taken using a disposable paper stick-on bitetab. (B) Bitewing radiograph taken using a thicker plastic, autoclavable image receptor holding device. Notice the wider space between the occlusal surfaces of the maxillary and mandibular teeth.

Horizontal and Vertical Angulation Procedures Horizontal angulation Point of entry

TABLE 16-3 Summary of Steps for Acquiring Bitewing Radiographs

TABLE 16-3 (continued) Summary of Steps for Acquiring Bitewing Radiographs

Figure 16-13 Horizontal angulation Figure 16-13 Horizontal angulation. (A) Mesiodistal projection of the x-ray beam shown here deviates from a right angle by about 15º, resulting in greater overlap of the contacts in the posterior region of the radiograph. (B) Correct horizontal projection of the x-ray beam produces no overlapping. (C) Distomesial projection of the x-ray beam shown here deviates from a right angle about 15º, resulting in greater overlap of the contacts in the anterior region of the radiograph.

Figure 16-14 Horizontal overlap error Figure 16-14 Horizontal overlap error. (A) When the PID is directed obliquely from the mesial (mesiodistal projection of the x-ray beam), the overlapping will be more severe in the distal or posterior region of the image. (B) When the horizontal angulation is directed obliquely from the distal (distomesial projection of the x-ray beam), the overlapping will be more severe in the mesial or anterior region of the image.

Figure 16-15 Avoiding molar overlap when using a holder with external aiming device. (Courtesy of Dentsply Rinn.) (A) Note the recommended premolar bitewing placement positions the image receptor slightly diagonal with the front edge of the image receptor farther from the lingual of the teeth than the back part. (B) Because the proximal surfaces of the molar teeth are in a mesiodistal relationship to the sagittal plane, it is recommended that the image receptor be positioned perpendicularly to the embrasures, resulting in a diagonal placement similar to the premolar position.

Figure 16-16 Vertical angulation error Figure 16-16 Vertical angulation error. (A) Inadequate vertical angulation results in imaging more of the mandible. (B) Excessive vertical angulation results in imaging more of the maxilla.

Figure 16-17 Central incisors bitewing exposure Figure 16-17 Central incisors bitewing exposure. (A) Diagrams show the relationship of the image receptor and holder, teeth, and PID. (B) Vertical angulation is directed perpendicular to the image receptor at approximately +10° with the PID tilted downward. Central ray is directed at the center of the image receptor at a spot on the incisal plane between the maxillary and mandibular teeth. (C) Patient showing position of image receptor holder and 12-in. (30-cm) circular PID. (D) Central incisor bitewing radiograph. In the anterior region, the image receptor is positioned with the long dimension vertical.

Figure 16-18 Canine bitewing exposure Figure 16-18 Canine bitewing exposure. (A) Diagrams show the relationship of the image receptor and holder, teeth, and PID. (B) Vertical angulation is directed perpendicular to the image receptor at approximately +10° with the PID tilted downward. Central ray is directed at the center of the image receptor at a spot on the incisal plane between the maxillary and mandibular teeth. (C) Patient showing position of image receptor holder and 12-in. (30-cm) circular PID. (D) Canine bitewing radiograph. In the anterior region, the image receptor is positioned with the long dimension vertical.

Figure 16-19 Premolar bitewing exposure Figure 16-19 Premolar bitewing exposure. (A) Diagrams show the relationship of the image receptor and holder, teeth, and PID. (B) Vertical angulation is directed perpendicular to the image receptor at approximately +10 degrees with the PID tilted downward. Central ray is directed at the center of the image receptor at a spot on the occlusal plane between the maxillary and mandibular teeth. (C) Patient showing position of image receptor holder and 12-in. (30-cm) circular PID. (D) Horizontal premolar bitewing radiograph. (E) Vertical premolar bitewing radiograph. In the posterior region, the image receptor may be positioned with the long dimension horizontal or vertical.

Figure 16-20 Molar bitewing exposure Figure 16-20 Molar bitewing exposure. (A) Diagrams show the relationship of the image receptor and holder, teeth, and PID. (B) Vertical angulation is directed perpendicular to the image receptor at approximately +10 degrees with the PID tilted downward. Central ray is directed at the center of the image receptor at a spot on the occlusal plane between the maxillary and mandibular teeth. (C) Patient showing position of image receptor holder and 12-in. (30-cm) circular PID. (D) Horizontal molar bitewing radiograph. (E) Vertical molar bitewing radiograph. In the posterior region, the image receptor may be positioned with the long dimension horizontal or vertical.

Review: Chapter Summary Bitewing radiographs image the coronal portion of both maxillary and mandibular teeth on one film. Bitewing radiographs supplement and complete the full mouth survey because of their improved ability to image incipient caries in the tooth contact areas and early resorptive changes in the alveolar bony crest.

Review: Chapter Summary The size and number of images to expose depend on the type of survey required and the size and shape of the patient’s oral cavity.

Review: Chapter Summary Image receptor holders/positioners include stick-on or loop bitetabs and instruments with external aiming devices that assist with determining the correct horizontal and vertical angulations and the points of entry.

Review: Chapter Summary The four basic steps to exposing a bitewing radiograph are placement, vertical angulation, horizontal angulation, and point of entry.

Recall: Study Questions General Chapter Review

Reflect: Case Study Study the dental chart and patient record. Note the dentist’s written prescription for a radiographic examination. Decide the following: What type of bitewings will most likely be exposed? What size film will best fit this patient? How many films will be required to complete the exam?

Reflect: Case Study Write out a detailed procedure for exposing each of the required radiographs. Include: Specific film packet placements. The vertical angulation required. How the horizontal angulation will be determined. What the point of entry will be.

Reflect: Case Study

Relate: Laboratory Application Proceed to Chapter 16, Laboratory Application, to complete this activity.