Stress distribution of esthetic posts in the restored maxillary central incisor

Abstract

Background: Glass fiber posts, along with their esthetic properties, may have a better stress distribution than cast posts, Therefore, the aim of the present study was to investigate the effect of glass fiber, casting, titanium, and zirconia posts on stress distribution in maxillary central tooth treated with different amounts of ferrule using finite-element analysis. Materials and Methods: In this experimental study, three-dimensional models of maxillary central incisors that have undergone root canal treatment were designed. Then, the models were divided into four groups according to the type of post (Ni-Cr casting, glass fiber, titanium, and zirconia) used. Zirconia monolithic crowns were used in all the four groups. Ferrule heights were repeated at 0 and 2 mm in all models. Models were entered into COMSOL Metaphysics software. Then, the force of 100 N with the angle of 135° on the palatal surface was applied to the longitudinal axis of the tooth, and the stress distribution in the models was investigated. Results: Maximum stress was observed in the middle third of posts. Stress distribution in glass fiber post was better than zirconia and casting posts. Stress accumulation in models with zirconia, titanium, and casting posts was also found in the site between the middle third and coronal third, whereas in models with glass fiber post, stress accumulation was found between the crown and the cemento-enamel junction. In models without ferrule, stress accumulation was observed in one-third of the coronal, especially in glass fiber posts. Conclusion: The post material and ferrule height affected stress concentration. The stress in the cervical area of the dentin was more for glass fiber post when compared to other posts. The use of glass fiber post in teeth with no ferrule results in lower stress along the post, but greater stress in the simulated tooth region.

Biomechanical Analysis of Mandibular Premolar Restored with Different Custom Post Core

“…15,16 Opposite of that some studies confirmed that the increased modulus of elasticity of the post reduces the stress in the dentin. 11,17 These facts are supported by studies with a follow-up period of 19.5 and 25 years, which indicate the longevity of teeth restored with custom cast post core. 18,19 Some authors presented those materials with a lower modulus of elasticity, such as fiber-reinforced composite posts (FRC posts), which lead to lower stress on the root structures and reduce the risk of root fracture, but have limited application in case of greater tooth destruction and lower resistance to fracture than custom cast post core.…”

“…The use of FRC posts in teeth without ferrule results in lower stress values along the post, but higher stress in the simulated region of the tooth, which supports the conclusion that their use is not indicated in teeth without a ferrule. 5,11,22 Durmuş and Oyar state that the highest stress values in the weakened root were measured in the tooth with carbon fiber post, while the Ni-Cr alloy posts showed the lowest stress values in the weakened root. The authors conclude that materials with a high modulus of elasticity cause less stress in the weakened root, but greater stress in the post itself.…”

“…[8][9][10] The vertical axial tooth structure that will be covered by the artificial crown is called metal ring or "Ferrule effect." 9,11 Sorensen and Engelman define the "Ferrule effect" as a 360 degrees metal ring or collar of the artificial crown surrounding the parallel dentine walls in the cervical part of the crown. 12 It is considered better to have even a partial ferrule effect rather than a complete lack.…”

Assessment of Fracture Resistance of PEEK and Fibre Posts of the Endodontically Treated Teeth

“…Finally, the results of this study might be directly related to the materials/ methodology utilized and might not reflect what could happen under different circumstances. The resin cement used was left to complete its setting at room temperature, which are few degrees less than body temperature [2,4]. As known with other adhesive cements, the polymerization shrinkage, degree of polymerization, timing and reaction kinetics may have been influenced by the conditions of the study.…”

“…However, as fiber glass posts are available as ready-made material, they have limited usage to the shape of the root canal. Furthermore, although fiber glass posts have reduced modulus of elasticity than those of different posts of metal alloy, these are still nearly three times the elastic moduli of dentin [4].…”