Finite element analysis and bond strength of a glass post to intraradicular dentin: comparison between microtensile and push-out tests.

OBJECTIVE: This study tested the hypothesis that the stress distribution and bond strength of glass posts to intraradicular dentin is influenced by the mechanical testing methodology. METHODS: Thirty single rooted endodontically treated teeth were prepared for luting of tapered fiber-glass posts (Reforpost, Angelus, Londrina, PR, Brazil) with a conventional adhesive system and resin luting cement (Adper Scotchbond Multi-purpose, Rely X ARC, 3M ESPE, St. Paul, MN, USA). The teeth were randomly divided (n=10 per group) into micro-push-out (Mpo), hourglass- (Mh) and rectangular stick-shaped (Ms) microtensile testing groups before sectioning each root into five 1-mm-thick specimens. During specimen preparation for microTBS testing 46/50 stick and 4/50 hourglass specimens prematurely failed; therefore, the Ms group could not be included in the mechanical testing. The remaining specimens were tested at 0.5 mm/min until bond failure. Stress distribution within each specimen type for the three mechanical test methods was analyzed by finite element analysis (FEA). Qualitative analyses were carried out through Von Mises, XY and Sy criterion. RESULTS: Mpo and Mh had a mean microTBS of 11.89+/-6.55 and 14.98+/-12.72 MPa, respectively, which was not significantly different (p=0.1311). The push-out test demonstrated a more homogenous stress distribution by FEA and less variability in mechanical testing. SIGNIFICANCE: Therefore, the recommended testing method for determining the bond strength of glass posts to intraradicular dentin is by Mpo.

Influence of different post design and composition on stress distribution in maxillary central incisor: Finite element analysis.

BACKGROUND: Post design and material has very important effects on dentinal stress distribution since the post placement can create stresses that lead to root fracture. MATERIALS AND METHODS: In this study we use finite element analysis (FEA) to evaluate stress distribution on endodontically treated maxillary central incisors that have been restored with different prefabricated posts. Six models were generated from the image of anatomical plate: Four metallic posts (ParaPost XH, ParaPost XT, ParaPost XP, and Flexi-Flange) and one fiberglass post (ParaPost Fiber Lux). The sixth model was a control-a sound maxillary central incisor. We used CAD software and exported the models to ANSYS 9.0. All the materials and structures were considered elastic, isotropic, homogeneous, and linear except the fiberglass post which was considered orthotropic. The values for the mechanical properties were obtained by a review of the literature and the model was meshed with 8-node tetrahedral elements. A load of 2N was applied to the lingual surface at an angle of 135 degrees. RESULTS: The stress results were recorded by shear stress and von Mises criteria; it was observed that there was no difference for stress distribution among the titanium posts in the radicular portions and into posts. There was higher stress concentration on the coronary portion with the titanium posts than with the glass fiber post. It seems that the metallic posts' external configuration does not influence the stress distribution. CONCLUSION: Fiber posts show more homogeneous stress distribution than metallic posts. The post material seems to be more relevant for the stress distribution in endodontically treated teeth than the posts' external configuration.

Uso de coroa em cerâmica pura associada a pino de fibra de vidro na reabilitação estética do sorriso: relato de caso / All ceramic crown associated to fiberglass post: a clinical case report

Restauração de dentes tratados endodonticamente constituidesafio permanente na odontologia, uma vez que aspectos biomecânicos,estéticos e complexidade de execução técnica podemresultar em insucesso com consequente perda do elemento dentário.Geralmente dentes tratados endodonticamente se encontramenfraquecidos devido à perda de estrutura dentária o queresulta em redução de resistência mecânica da dentina. Estesfatores resultando em maiores riscos de falhas biomecânicasquando comparados aos dentes com vitalidade pulpar. Este trabalhotem por objetivo apresentar procedimentos clínicos reabilitadorespara devolução de harmonia estética com ênfase emprocedimentos realizados em incisivo central superior com extensaperda de estrutura coronária e restauração em resina compostainsatisfatória. Foi empregada a associação de pino de fibrade vidro (Exacto, Ângelus) e resina composta para reconstruçãointerna seguido de coroa em cerâmica pura (In Ceram Alumina,Vita). São destacados os passos clínicos e breve revisão de aspectosbiomecânicos e estéticos desta alternativa reabilitadora.

Restoration of endodontically treated teeth is a challenge inoperative dentistry, since the biomechanical, aesthetic and complexityof the technique can result in failure with subsequenttooth loss. Generally endodontically treated teeth are weakeneddue to loss of tooth structure and reduce the mechanicalstrength of dentin. These factors result in a higher risk of biomechanicalfailure when compared to teeth with pulp vitality.This paper aims to present clinical rehabilitation procedures torecover the smile harmony with an emphasis on aesthetic proceduresperformed in the maxillary central incisor with extensiveloss of coronal tooth tissue and unsatisfactory compositeresin restoration. It was employed the combination of fiberglasspost (Exacto, Angelus) and coronal reconstruction with compositeresin followed by all ceramic alumina crown (In CeramAlumina, Vita). Highlights the clinical steps and brief review ofbiomechanical and aesthetic rehabilitation of this alternative aredescribed.