Cracked tooth? Craze lines vs vertical root fractures

Craze line – differentiated from cracks via trans-illumination
Fractured cusp
Cracked tooth – differentiated from last two via wedge test.

The long-term prognosis for a cracked tooth is better when no crack is visible or the crack does not extend to the chamber floor and the tooth becomes pain free by banding or the placement of a temporary crown.
A small 2006 study finds two-year survival rate of cracked teeth to be 85.5 percent. This study indicates that the only significant prognostic factors were teeth with multiple cracks, terminal teeth in the arch and pre-root filling pocketing.

Split tooth

Vertical root fracture

A vertical root fracture will hurt when biting. It will often typically have a deeper probing score in the are of the fracture. It can be subjective and we feel there is a fair amount of over-diagnosis of vertical root fracture when it’s really just an endo failure. It’s easy for a dentist to say there must be a fracture when a tooth with a root canal and looks fine is not feeling fine. The reality is that due to the variable and complex anatomy some teeth are too complex to treat well with endodontics consistently. These failures are often ascribed as vertical root fractures.

These misdiagnosis cases do not impact the case by case as a tooth that can not be successfully treated with endodontics needs extraction the same way one with a vertical root fracture does. However, the real problem is when it shows up in research articles that are meant to guide treatment guidelines. Kim JOE 2024 finds 21% of their teeth that have implants had a tooth with a vertical root fracture. The definition was “suspected root fracture”, which is code for failure of root canal for unknown reasons often times. Anyway that bias then results in fewer root canals “failing” and muddies their results.

$Picture of a vertical root fracture on a premolar$