The definite diagnosis of a dentinal crack is based on a direct visual examination. The crack should be visualized on/in the crown to confirm its presence. However, most of the time the tooth has a crown or a MOD filling, hiding the underlying crack. If so, how can a crack be visualized in such situations?
To answer this question plain and simple, it should be said you don’t need to visualize the crack in these cases! Just use the extra coronal findings to diagnose the crack.
A fracture detector like Tooth Slooth would help diagnose cracked teeth. The pain is elicited once the patient releases the bite. Equally important is the presence of an isolated narrow deep periodontal pocket; the deeper the periodontal pocket, the deeper the crack, and consequently a worse prognosis. Yet another way to confirm the presence of a crack involves exploratory excavation to remove the existing filling. It also gives an opportunity to the dentist to stain the floor of the cavity.
Radiographically, the PDL at the cervical third is widened and the crestal bone looks fuzzy if the crack has reached the crestal bone (Figures 1-3). The dental CT scan may further help you diagnose a crack that is concealed by restorations. Again, the cervical third PDL is widened and the crestal bone was lost in an angular or tubular pattern (Figure 4).
The extra-coronal findings/tools to help diagnose a coronal crack are listed below:
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Case presentation:
A 40-year-old man was examined for a crack on tooth 2.6. A crack was noted on the mesial marginal ridge. Soft tissue was normal. The tooth was sensitive to percussion and did not respond to cold test. Mobility was +1. The periodontal probing was (from mesial to distal) B 6, 2 ,5 & P 6 ,2 ,4. Note the 6 mm pockets at the mesial associated with the crack. The periodontal depth at the other areas of the mouth was normal.
The radiography demonstrated crestal bone loss at the mesial (Figure 5). The dental CT scan revealed an isolated extensive crestal bone loss at the mesial (Figure 6, red arrow). Interestingly, the crack line was apparent, although this is not a usual finding (Figure 6, yellow arrows). The diagnosis was pulpal necrosis, symptomatic apical periodontitis, and crack.
The presence of 6-mm pockets implied deep crack. It means the crack has reached the mesial pulpal wall.
Case presentation:
A 40-year-old man was examined for a crack on tooth 2.6. A crack was noted on the mesial marginal ridge. Soft tissue was normal. The tooth was sensitive to percussion and did not respond to cold test. Mobility was +1. The periodontal probing was (from mesial to distal) B 6, 2 ,5 & P 6 ,2 ,4. Note the 6 mm pockets at the mesial associated with the crack. The periodontal depth at the other areas of the mouth was normal.
The radiography demonstrated crestal bone loss at the mesial (Figure 5). The dental CT scan revealed an isolated extensive crestal bone loss at the mesial (Figure 6, red arrow). Interestingly, the crack line was apparent, although this is not a usual finding (Figure 6, yellow arrows). The diagnosis was pulpal necrosis, symptomatic apical periodontitis, and crack.
The presence of 6-mm pockets implied deep crack. It means the crack has reached the mesial pulpal wall.
Conclusion and comment:
Periodontal probing is a reliable tool in the diagnosis of a crack when it is not visible. Like vertical root fractures, the reason that a dental CT scan is ordered to detect a crack is to help evaluate the pattern of bone loss, not to see the crack line.
Reference:
1- Survival of root filled cracked teeth in a tertiary institution, Tan et al
Int Endod J 2006
2- Correlation between symptoms and external characteristics of cracked teeth: findings from The National Dental
Practice-Based Research Network, Hilton et al
J Am Dent Association 2017
3- 12-month Success of Cracked Teeth Treated with Orthograde Root Canal Treatmen, Krell and Caplan
JOE 2018