4. DISCUSSION
Tiny cracks are common and usually do not cause problems. In such cases regular checkups are important to manage such problems in early stage. Various treatment modalities are available for advanced cracks (incomplete fracture). The choice depends on the location, direction and extent of the crack. Cracks may be superficial, affecting the cusp of a tooth or deep to involve the root of the tooth. Some affect only the enamel; others may extend to the dentin or the pulp. Before treatment, reduction or elimination of occlusal contacts is essential to avoid an overload of a split tooth 2.
Tenderness on biting and pain with cold, sweet or hot or a combination of these are common complains of a cracked tooth. These symptoms can be explained by the hydrodynamic theory of pain first described by Feiglin4 and substantiated experimentally by Brӓnnstrӧm5. This theory is based on the concept that rapid movement of dentinal fluid in the dentinal tubules causes pain. This movement stimulates mechano-receptors in close proximity to the odontoblast cell body, which then activate delta nerve fibers (faster myelinated fibers), resulting in a short sharp pain.
Simvastatin is a new therapeutic material in the field of dentistry and still under dental research. Its structural analogs of HMG-CoA (3-hydroxy-3-mthylglutaryl-coenzyme A) that are considered to be the first-line to control hyperlipidemia and it has been recognized as a safe and low-priced drug with worldwide longtime usage6,7. Moreover, statin has multiple functions including anti-inflammation, induction of angiogenesis and improvement of the vascular endothelial cell function. In addition, several statins products have anabolic effects on bone metabolism 8and promote mineralization in non-mineralizing osteoblasts through induction of Bone Morphogenic Protein- 2 and osteocalcin9. Simvastatin also proved to promote differentiation of osteoplastic cells in mice 10.
Crack sealed by dentin is considered the proper biological and mechanical management of tooth crack. Simvastatin was used in this clinical report as a intra-canal medicament to seal the tooth crack because previous experimental studies proved that it can stimulate bone11 and dentin formation 12. Painful symptoms disappeared during the rest treatment which proved the therapeutic effects of simvastatin. The exact mechanism or mode of action of simvastatin in the crack seal is not known. However, the anti-inflammatory action of statins may explain the rapid relief of pain after application of the material inside the canal 8.
The use of simvastatin in the current case is considered as an empirical treatment that was based on experimental studies and further clinical studies should be conducted for investigation of its side effects and mode of action before its approval to be used in endodontics. Regardless the results of this case, the clinicians can apply this approach only when they have scientific evidence.
CONCLUSION
Fracture is one of the most common causes of tooth loss, therefore, it is important to avoid or eliminate risk factors which contribute to tooth fracture. The key factor is early diagnosis and treatment of the cracks so that they can be halted, or their progression slowed down. Simvastatin allowed a good management for a case suffered from cracked tooth.