Influence of Post and Resin Cement on Stress Distribution of Maxillary Central Incisors Restored with Direct Resin Composite

Abstract

According to finite element analysis, the zirconia ceramic post created higher stress levels in the post and slightly less in dentin compared with glass fiber posts. Resin cement with a high elastic modulus created higher stress levels in the cement layer. The different film thicknesses of cement did not create significant changes in stress levels. SUMMARYThe current study evaluated the influence of two endodontic post systems and the elastic modulus and film thickness of resin cement on stress distribution in a maxillary central incisor (MCI) restored with direct resin composite using finite element analysis (FEA). A three-dimensional model of an MCI with a coronary fracture and supporting structures was performed. A static chewing pressure of 2.16 N/mm 2 was applied to two areas on the palatal surface of the composite restoration. Zirconia ceramic (ZC) and glass fiber (GF) posts were considered. The stress distribution was analyzed in the post, dentin and cement layer when ZC and GF posts were fixed to the root canals using resin cements of different elastic moduli (7.0 and 18.6 GPa) and different layer thicknesses (70 and 200 µm). The different post materials presented a significant influence on stress distribution with lesser stress concentration when using the GF post. The higher elastic modulus cement created higher stress levels within itself. The cement thicknesses did not present significant changes.

Zirconia ceramic post systems: a literature review and a case report

“…Of these papers, 62 were in vitro studies 12,14,29,32,33,35, , three were clinical studies 27,28,95) , and 14 were case reports and review articles with clinical application guidance 18,[24][25][26][96][97][98][99][100][101][102][103][104][105] . Of the 62 in vitro studies, 29 studies investigated the fracture strength 12,14,29,33,35, , 21 studies investigated the retentive strength of zirconia posts to both the tooth and cores of different materials , three studies investigated the microleakage of endodontically treated teeth restored with different post systems [88][89][90] , and four studies investigated the stress distribution in teeth restored with zirconia posts by using finite element analysis [84][85][86][87] . Other in vitro studies examined the yield strength 91) , radiodensitiy 92) , esthetic properties 32) , marginal gap formation 93) , stiffness and elastic limit 59) of zirconia posts, as well as the use of a proof-test technology to eliminate low-quality zirconia posts with critical microscopic defects so as to help reduce clinical failures 94) .…”

“…On one hand, Eraslan et al 84) and Spazzin et al 87) reported that the stress values observed with zirconia posts were higher than with FRC posts, and they attributed this result to the high elastic modulus of zirconia. On the other hand, Toksavul et al 85) and Asmussen et al 86) suggested that zirconia posts created slightly less stress concentration in dentin than FRC and titanium posts.…”

“…Four studies examined the stress distribution of teeth restored with zirconia posts by using finite element analysis [84][85][86][87] . On one hand, Eraslan et al 84) and Spazzin et al 87) reported that the stress values observed with zirconia posts were higher than with FRC posts, and they attributed this result to the high elastic modulus of zirconia.…”

Influence of remaining coronal structure and finish line on the fracture strength of roots restored with metallic posts

“…1 In these cases, the use of posts is recommended to promote retention of the final restoration. [2][3] The preservation of tooth structure is an important factor in the successful restoration of endodontically treated teeth. Some authors 4,5 have suggested that a tooth should have a minimum amount (2 mm) of coronal structure above the cementoenamel junction (CEJ) to ensure a proper shape of strength for a tooth.…”

Microhardness of luting agents used for fiber post cementation submitted to thermo cycling

“…These posts have two major functions which are to increase the resistance against fractures of the root and provide retention for the core material. [4][5][6] However, the flexural strength and survival probability of restorations containing post and core depend on several factors, such as: Quantity and condition of remaining dental tissue, tooth preparation for restorative procedure, and characteristics of fixed restoration, such as luting line, bonding procedures, post and core materials, and type of cement. [7][8][9] The resin cements provide increased retention and increasing the fracture toughness of the roots, compared to the conventional cements.…”