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March 2007 – Why Bite Wings are Important when Examining Crowns
|This male patient was referred to me initially with a single periapical film (Fig. 1). The dentist said that the pain was exhibiting signs of irreversible pulpitis with periradicular involvement. There was some PDL thickening noted at the mesial root apex but the crown otherwise look reasonably good. I noted that the referral’s film appeared to be slightly foreshortened.
When the patient arrived in my office, standard diagnostic procedures were used. This included the policy that all teeth with crowns must have bite wing radiographic images in order to assess the integrity and quality of the proximal margins.
My initial periapical image showed what appeared to be a discrepancy along the mesial crown margin. Because the image was taken without use of a paralleling device, I told my assistant that I felt the image was still slightly foreshortened. The bite wing radiograph (Fig.2) confirmed my suspicions. There was massive decay under the crown margin that was confirmed by exploration in the mouth.
At that point I sat the patient up and explained my findings. While the patient was originally under the impression that the endodontic treatment would be routine, and would merely involve access through the crown, we now had an entirely different scenario. The crown would need to be removed and I told the patient that I actually suspect that the tooth may not be restorable.
The crown was removed and the decay explored down to sound dentin. At this point not only was the decay subgingival, it was approaching the osseous crest. (Fig 3 Yellow arrows show mirror image of mesial decay)
I consulted a Periodontist to assess restorability. He suggested that the osseous recontouring procedures that would be involved in obtaining a proper margin would likely involve the furca bone. At that point, the prognosis goes down appreciably. I also noted that the patient has a history of major buccal smooth surface decay in the adjacent restored premolars.
I phoned the referral and told him that considering the patient’s hygiene history, need for extensive periodontal and osseous treatment, as well and the endo and new crown requirement – extraction might be a better option. The patient was referred back to the referring dentist for discussions regarding prosthetic replacement.
This consultation appointment was really unnecessary. Had the referral taken the time to take a good Bite Wing image, he would have seen the decay, removed the crown, determined the non-restorability of the tooth and probably have saved the patient the needless expense of a trip to my office.
Figure 1 - Referral PA image
Figure 2 My Bite Wing
Figure 3 Unrestorable carious involvement