Stress distribution in different type of post and core



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Stress distribution in different type of POST AND CORE

Borcic J, Antonic R, Gla┼żar I, Muhvic Urek M, Catic A, Petricevic N.


Objectives:

Post and core applications are generally used in the restoration of endodontically treated teeth. The stress distribution during masticatory function in a tooth restored with post and core can cause root fracture. The different mechanical behaviour of post and dentine is a critical parameter for the load transmission. In order to minimise the rigidity difference between the dentine and the post, a new kind of prefabricated posts were developed.

The aim of the study was to analyse the mechanical behaviour of a new polymeric composite post reinforced with glass fibres vs cast post and core through 3D finite element analysis. A natural tooth was considered as a reference model.

Methods:


Models have more than 1,5 million elements and an average loading force of 200 N was used to simulate biting forces in the two different occlusal conditions. First condition represents so called normal occlusion with tripodal occlusal contact. Second condition represents malocclusion with single contact on the palatal cusp. The load vectors were applied in the direction normal to the surface in order to simulate the contact with antagonistic teeth.

Results:


Endodontic posts take some of the stresses on themselves and values are smaller on the surface of the tooth. In the case of normal occlusion stress distribution is the same for sound and restored tooth, dissimilarity exsists in the values od stresses. Significantly higher tensile stress values were recorded for the cast post and core restored tooth. At the root furcation, tensile stress appeared only in the restored tooth. In the case of normal occlusion, tensile stress at root furcation occurs only in the model with cast post and core.

Conclusions:



Cast posts resulted in significantly higher stress values. Tensile stresses are much harmful for the tooth tissue and this type of stress occurs at the root furcation only in the restored tooth, esspecially in the cast post and core.


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