Biomechanical perspectives on dentine cracks and fractures: Implications in their clinical management

Objectives: The present review discussed the biomechanical properties of cracks and fractures in crown and root dentine and attempted to explain why cracked teeth and vertical root fractures are so frequent despite the ex-istence of multiple crack toughening mechanisms in dentine. The implications of this knowledge were used to justify how these defects are managed clinically.Data, Sources and Study selection: Literature search was conducted on PubMed, Web of Science, and Scopus for a narrative review on fracture mechanics of crown and root dentine as well as the clinical management of cracked teeth and teeth with vertical root fracture. Conclusions: Although dentine is tougher and less brittle than enamel, it's facture toughness is considerably lower than most ductile metals. Because the initiation toughness of dentine is very low, cracks initiate from incipient damage under low stress While crack toughening mechanisms exist that enable dentine to resist crack extension, these mechanisms are often inadequate for protecting dentine from crack propagation that ultimately leads to catastrophic failure. Additional factors such as ageing also reduces the resistance of dentine to crack growth. Because dentine cracks are eventually filled with bacteria biofilms upon exposure to oral fluids, they enable rapid bacteria ingress into the dental pulp via open dentinal tubules. To date, treatment options for cracked teeth are limited. While most teeth with vertical root fracture are recommended for extraction, new strategies have been reported that appeared to achieve short-term success in preserving these teeth. Clinical Significance: Current strategies for the management for dentine cracks and fractures are limited and their long-term effectiveness remain uncertain. Understanding the characteristics, toughening mechanism and weakening factors of tooth cracks is helpful in designing better treatment.