Intense dental-related pain is sometimes difficult to localize. In some of these cases, the pain is perceived in different regions from where it had originated. This occurrence is known as referred pain. Referred pain is caused by spreading the noxious excitation of the stimulated nerve to other portions of its segment or to adjacent segments. In the oral cavity, pain can be referred to adjacent teeth in the same jaw quadrant and frequently to the opposing jaw on the same side (eg, pain from maxillary molars can be referred to mandibular molars and vice-versa). Pain rarely, if ever, crosses the midline. However, Friend and Glenwrigth1 found that by electrically stimulating a group of teeth, pain was produced on the opposite half of the mandible in 1.5% of all the test cases; almost all of those teeth were anteriors.
Referred pain is usually caused by teeth having a partially inflamed pulp (partial pulpitis). Once the pulpal inflammation is complete (total pulpitis), the apical periodontal ligament becomes involved, and the tooth is then sensitive either to percussion or apical palpation, or both. Unfortunately, sometimes pain localization takes several days or even weeks, during which time the patient can be in intense pain. Therefore, it would be advantageous to be able to determine the etiology of the referred pain as soon as possible.
As an endodontist, author CK occasionally has patients referred to him who are in moderate to severe pain, but are unable to localize its source. Usually, the patient presents with one or more periapical radiographs of the apparent involved jaw quadrant. When most endodontists are faced with this situation, they may take additional periapical radiographs. Periapical radiographs are sufficient to show periapical pathosis and obvious caries. However, because of coronal overlap, less evident caries, fractures, and dental procedures (such as depth of drilling) may be hidden. Considering these potential problems with periapical films, in cases of possible referred pain CK always takes bite-wings of the same side of the jaw.
Bite-wings
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Figure 1a. In this periapical film, dental intervention is not apparent in the mesial region of the coronal aspect of the mandibular right first molar. |
Figure 1b. With this bite-wing film, in the mandibular right first molar a channel can be seen (see arrows) caused by the general dentist who attempted to obtain relief for the patient’s pain. |
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Figure 2a. In this periapical film, recurrent caries is not apparent under the distal-facial region of the mandibular right second molar. |
Figure 2b. In this bite-wing film, recurrent caries can be seen in the distal-facial region of the mandibular right second molar (see arrow). |
CK has had a special interest in dental radiography for more than 15 years. A major observation of his was that because of lack of coronal distortion, bite-wing radiographs give a truer picture of dental caries, defective margins, recurrent caries, furca involvement, and depth of dental drilling. Figures 1a and 1b show a case of depth of dental drilling. Figures 2a and 2b show recurrent decay under a coronal restoration. Figures 3a and 3b show a possible case of furca involvement. In addition, bite-wing radiographs show the same characteristics of teeth in the opposing jaw. With this knowledge in mind, CK did a clinical study of patients who were referred with moderate to severe pain but were unable to localize the source of the pain.
CASE STUDIES
| Table. The 52 Cases of Referred Pain of Dental Origin in Order of Their Occurrence From 1997 to 2007. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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