A comparative evaluation of fracture load of monolithic and bilayered zirconia crowns with and without a cervical collar: an in vitro study

Abstract

Introduction. The use of zirconia based all-ceramic restorations are preferred nowadays owing to superior biologic and esthetic properties. However, these restorations have also reported higher incidences of fracture and chipping. The clinical success may be enhanced by optimizing the core design, through the introduction of monolithic zirconia, or the layered crowns can be strengthened by adding the cervical collar to them.
 Objective. This study was performed with the objective to compare and evaluate the fracture load of monolithic and bilayered zirconia crowns with and without a cervical collar.
 Methods. A prospective observational study was carried out to compare 45 fabricated zirconia crowns of three different designs on a customized metal mould. The samples were oriented on the metal mould and subjected to confocal microscope for the evaluation of marginal integrity followed by cementing the crown on the metal mould and subjecting it to the universal testing machine for the analysis for the flexural strength. Data were analyzed using one way Anova and t- test for inter and intra groups. The significance level was set at P ≤ 0.05.
 Results. The monolith zirconia crowns and layered zirconia crowns with cervical collar reported more flexural strength .
 Conclusion. The amount of force required to fracture the zirconia crowns was higher in the case of monolith zirconia crown and layered zirconia crown with cervical collar as compared to the layered zirconia crown without cervical collar.

Evaluation of Marginal/Internal Fit and Fracture Load of Monolithic Zirconia and Zirconia Lithium Silicate (ZLS) CAD/CAM Crown Systems

“…Different types of zirconia-based ceramics have been made available in recent years for the restoration and replacement of both anterior and posterior teeth through a variety of fabrication techniques, including computer-aided design and computer-aided manufacture (CAD/CAM) [ 3 , 4 ]. Although zirconia (Zi) has favorable mechanical properties for a variety of applications in dentistry, the white color and poor translucency of the material precluded the use for full contoured restorations in the past [ 5 , 6 , 7 , 8 , 9 ]. Recently, translucent tooth-colored Zi, which enables fabrication of restorations without the veneering porcelain, has been developed [ 10 , 11 , 12 ].…”

Evaluation of zirconia and zirconia‐reinforced glass ceramic systems fabricated for minimal invasive preparations using a novel standardization method

“…To avoid fracture and facilitate the manufacturing processes zirconia restorations are currently used in a monolithic design without being veneered. Different studies 7,8 reported that monolithic zirconia crowns have a higher fracture resistance than conventional veneered versions.…”

Bending Fracture of Different Zirconia-Based Bioceramics for Dental Applications: A Comparative Study

“…However, these bilayer structures were vulnerable to chipping and the delamination of veneered ceramics, thus affecting their long-term survival [5]. Due to these aspects, practitioners and producers were determined to turn to monolithic anatomic restorations instead, which had enhanced mechanical strength and toughness as well as greater simplicity in their fabrication [23,32].…”