03 November 2022

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Cracked teeth syndrome: are they repairable?

Lara Figini

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Dental cracks always represent a problem that is difficult to manage and diagnose by the dentist. The prognosis of a cracked tooth tends to be better in teeth where the fracture line ends within the coronal third of the root. 

Such cracks give a typical bone resorption surrounding the fracture line, which is pathognomonic of the condition and often allows for definitive diagnosis. The etiopathogenesis of inflammation in radicular cracked teeth is attributable to bacterial penetration of periodontal pockets through the fissure line and localized bone resorption that occurs in a cracked tooth can be detected as a probing defect using a periodontal probe. However, the initially narrow pocket is often difficult to detect and only becomes more noticeable as it progresses. 

The most accredited hypothesis in this regard proposes that longitudinal fractures originate from a crack in the dentin of the crown secondary to a chewing stress or due to weakened dentin (decreased in quantity or altered in quality) which can therefore break more easily, resulting in an incomplete fracture. 

Chewing stress leads to an extension of the fracture downward to the pulp chamber resulting in infection and dental necrosis in many cases. Additional stresses on the tooth promote the extension of the fracture towards the root, which allows bacterial penetration deeper into the periodontium. Patients can present with a wide variety of clinical symptoms that are often difficult to associate with a crack, because the symptoms tend to disappear, or they can be widespread and often not attributable to a single tooth or a specific problem. Researchers and clinicians have tried to establish an effective therapeutic approach to preserve these teeth or at least to prolong their stay in the arch and not immediately resort to avulsion.

Materials and methods

In a retrospective observational study published in the International Endodontic Journal in October 2021, the authors studied the survival rate of teeth with root cracks restored with composite materials. 

The study included 87 teeth with root cracks or cracks in 87 patients (46 men, 41 women) with a mean age of 50.2 years who were treated with adhesive composite restorations between 1991 and 2019. 

Forty-five cracks were found in the upper posterior teeth (molars and premolars), 40 in the mandibular posterior teeth and only two in the anterior teeth, both at the maxillary level. 

Based on the depth of the crack, the teeth were classified with proximal root cracks (PRCT), in which the fracture line was limited within the pulp floor or coronal third of the root, and with deep root cracks (DRCT), where the fracture line extended to the middle third and apex of the root canal. 

Bone loss and recovery was assessed radiographically at one year. All patients were treated with surgical microscopy by the same operator. A logistic regression analysis was performed to determine independent predictors of extraction. Kaplan – Meier survival curves were used to analyze PRCT and DRCT.

Results

Among 87 cracked teeth, 66 were molars, 19 premolars and two incisors. Fifty-two were DRCT, 35 were PRCT, 46 had a periodontal probing defect. 

Patients were followed for a mean of 66.9 months (standard deviation 44.6, min 1 to max 172). Lack of probing depth was a significant protective factor against extraction (odds ratio [OR] 0.027, 95% confidence interval [CI] 0.003-0.27, p < .05), whereas further bone loss (OR 10.63, 95% CI 2.08-54.36, p < .05) was a risk factor for extraction. 

More than 50% of teeth treated with the adhesive protocol were functional (46 of 87 teeth [χ2 test], p < .05) at a five-year follow-up. Among the PRCT group, a 78% survival rate at five years was found, while among the DRCT group, a 58% survival rate was found.

Conclusion

Composite resin restorations resulted in tooth survival in less than 50% of patients; 85.4% of PRCT and 61.5% of DRCT were functional after five years of follow-up.

Clinical implications

The long-term prognosis of composite resin restorations of vertical root cracks appears promising. However, the use of an operating microscope is essential for diagnostic and therapeutic procedures.

Augusto Malentacca, Fabrizio Zaccheo, Matteo Scialanca, Francesco Fordellone, Cosimo Rupe, Carlo Lajolo. "Repair of teeth with cracks in crowns and roots: An observational clinical study." Int Endod J. 2021 Oct;54(10):1738-1753. DOI: 10.1111/iej.13598