Finite Element Evaluation of Stress Distribution in Mature and Immature Teeth
INTRODUCTION: Traumatic injuries may affect the vitality and development of tooth. So divergence or parallelism of canal walls induces an open apex which is very susceptible to fracture. The aim of this study was to determine the stress distribution pattern in immature teeth and compare it with mature teeth. MATERIALS AND METHODS: In order to analyze stress distribution using finite element method, models were first designed according to actual samples by "ANSYS" software. Two models of the maxillary central incisors were designed, one mature and one with open apex. Mature tooth was designed as having undergone root canal therapy with gutta-percha and the immature one with both MTA plug and gutta-percha. Samples were loaded in seven stages and then, the stress distribution in each model was measured, using the "ANSYS" software. RESULTS: During gutta-percha condensation, the immature tooth transfers the stress directly to the external root surface where force is directly applied, whereas during masticatory occlusal forces, the stress is transferred to middle third of buccal and lingual surfaces and to buccal cervix in lunar shape. During traumatic forces, stress concentration was on the cervical region of buccal surface and middle third of buccal and lingual surfaces. MTA plug prevents stress distribution toward apical region and forces concentrate in dentin at the point where stress terminates. CONCLUSION: Within the limitations of this simulated mechanical analysis, it was confirmed that the pattern of stress distribution in mature and immature teeth is different. Cervical area of the buccal surface in immature teeth is one of the stress concentration areas, which contribute to the high rate of fracture in this area.
Avulsed immature incisor: From computed tomography to finite element analysis
Dental trauma represents the second etiology for tooth loss. Understanding of its mechanism in relation to ora-facial structures is essential for clinical reason. Due to its mechanical nature, the trauma can be investigated accurately using mathematical methods (finite element methods). A geometrical model was obtained from the computer tomograph scans of a immature upper incisor, further processed in dedicated FEA (Finite Element Analysis) software. Similar results with previous studies were achieved, confirming the validity of the model and the reliability of the path from DICOM (Digital Imaging and Communications in Medicine) files to compliant finite element method object. The results sustain the epidemiological findings, enamel fractures being detected more often than other clinical forms.
In vitro resistance of composite resin dowel and cores.
In the spectrum of treatment modes of endodontically treated molars, composite dowel and core systems are considered an alternative to the widely used cast dowel and core method. In a laboratory setting under oblique loading with a slowly increasing force, no significant differences between the tested composite dowel and core systems could be detected. All systems could resist forces of more ythan 2,000 N. Long-term clinical evaluations should give the ultimate answer about their durability and the influence of other possible destructive factors.