Influence of material and diameter of pre‐fabricated posts on maxillary central incisors restored with crown

Abstract

Numerous research works have studied the effect of post-design parameters on the mechanical behaviour of restored teeth without reaching any clear conclusions. Previous works by the authors ascertained the effect of material and post-dimensions for non-crowned restored teeth. The aim of this work was to study the effect of post-material and diameter for crowned teeth. First, an experimental fracture strength test was performed on eighteen extracted human maxillary central incisors. Teeth were decoronated, treated endodontically and restored (nine with glass fibre posts and nine with stainless steel posts). Several post-diameters were used. The final crown restoration was carried out using a reinforced glass-ceramic material. Failure loads were recorded and results were compared using the one-way anova. Secondly, the finite element technique was used to model the restored teeth and to compare the estimated stress distributions. The addition of the crown did not affect the strength of the restoration to any significant extent and post-diameter did not influence the biomechanical performance of either of the post-systems. The crown acts as a protector, thus eliminating the influence of the post-diameter that was found previously when using stainless steel posts, but it does not completely rule out the possibility of a root fracture. Significantly, lower failure loads were found experimentally for teeth restored with stainless steel posts. The stress distributions predicted by the model corroborated these findings and allowed the authors to propose the use of glass fibre posts as a more robust restorative technique.

Biomechanical Models of Endodontic Restorations

“…These first works were twodimensional and were conducted with programs developed by the researchers themselves. Later, the advances in computer resources and in commercial software for FEA extended the use of different commercial programs, allowing more accurate and predictive threedimensional models to be developed Barjau-Escribano et al, 2006;Boschian Pest et al, 2006;Ferrari et al, 2008;Genovese et al, 2005;Gonzalez-Lluch et al, 2009b;Maceri et al, 2009;Rodríguez-Cervantes et al, 2007;Sorrentino et al, 2007). The number of publications dealing with FE simulation in endodontics has increased exponentially in recent years.…”

“…When cement layers are considered in the biomechanical model, they are usually represented with a constant small thickness Maceri et al, 2009;Okamoto et al, 2008;Schmitter et al, 2010). However, some works simplify the model by obviating the cement in the interface between the core and the crown (Gonzalez-Lluch et al, 2009b;Lanza et al, 2005) or even in the interface between the post and the root (Adanir & Belli, 2007;Hsu et al, 2009). Several types of endodontic posts can be found in the literature (Christensen, 1998;Fernandes et al, 2003).…”

“…Three-dimensional models have been used extensively for simulating endodontic treatment since the beginning of the century Ausiello et al, 2002;BarjauEscribano et al, 2006;Boschian Pest et al, 2006;Genovese et al, 2005;Lanza et al, 2005). In recent years some of the most complete three-dimensional models ever developed for studying the biomechanics of endodontic restorations have been reported (Ferrari et al, 2008;Garbin et al, 2010;Gonzalez-Lluch et al, 2009b;Maceri et al, 2009;Mezzomo et al, 2011;Okamoto et al, 2008;Schmitter et al, 2010). In these three-dimensional models, tetrahedral or hexahedral finite elements are used.…”

“…The geometrical representation of the different components of the restoration is obtained later in CAD using Boolean algebra. The authors recently used this procedure (Gonzalez-Lluch et al, 2009b) to obtain a realistic geometrical model of a maxillary central incisor, which is shown, in a sagittal section, in Fig. 3. …”

“…Not all models in the literature include the bone. When included, sometimes it is modelled with uniform properties (Imanishi et al, 2003;Nakamura et al, 2006), although most of the models consider the cancellous bone and a layer of cortical bone near the bone surface Gonzalez-Lluch et al, 2009b). Thin structures, such as the PDL and cement are not always considered in the FE models.…”