Fracture Resistance of Teeth Restored With All-ceramic Inlays and Onlays: An In Vitro Study

Abstract

Fracture resistance of inlays and onlays may be influenced by the quantity of the dental structure removed and the restorative materials used. The purpose of this in vitro study was to evaluate the effects of two different cavity preparation designs and all-ceramic restorative materials on the fracture resistance of the tooth-restoration complex. Fifty mandibular third molar teeth were randomly divided into the following five groups: group 1: intact teeth (control); group 2: inlay preparations, lithium-disilicate glass-ceramic (IPS e.max Press, Ivoclar Vivadent AG, Schaan, Liechtenstein); group 3: inlay preparations, zirconia ceramic (ICE Zirkon, Zirkonzahn SRL, Gais, Italy); group 4: onlay preparations, lithium-disilicate glass-ceramic (IPS e.max Press); and group 5: onlay preparations, zirconia ceramic (ICE Zirkon). The inlay and onlay restorations were adhesively cemented with dual polymerizing resin cement (Variolink II, Ivoclar Vivadent AG). After thermal cycling (5° to 55°C × 5000 cycles), specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. Statistical analyses were performed using one-way analysis of variance and Tukey HSD tests. The fracture strength values were significantly higher in the inlay group (2646.7 ± 360.4) restored with lithium-disilicate glass-ceramic than those of the onlay group (1673.6 ± 677) restored with lithium-disilicate glass-ceramic. The fracture strength values of teeth restored with inlays using zirconia ceramic (2849 ± 328) and onlays with zirconia ceramic (2796.3 ± 337.3) were similar to those of the intact teeth (2905.3 ± 398.8). In the IPS e.max Press groups, as the preparation amount was increased (from inlay to onlay preparation), the fracture resistance was decreased. In the ICE Zirkon ceramic groups, the preparation type did not affect the fracture resistance results.

Influence of surrounding wall thickness on the fatigue resistance of molars restored with ceramic inlay

“…It is possible that the load applied may not have been challenging enough to fracture the tested specimens. In a study performed by Saridag et al, 26 the mean fracture strength found in molar teeth restored by a lithium-disilicate ceramic inlay was 2646.7 (± 360.4) N. Thus, further studies are warranted to determine the influence of more challenging situations than those applied in the present study, including the use of higher loads, of test groups with non-restored teeth or inlays cemented with non-adhesive cements, and of test groups with the same wall thickness, but with cusp reduction.…”

Influence of the indirect restoration design on the fracture resistance: a finite element study

“…The width and depth of premolar preparations are important factors affecting tooth strength [14, 15]. The type of cavity preparation and materials also affect the extent of tooth fracture [16, 17]. …”

Fracture strength of composite resins for endodontically treated molars

“…[16,19,27] Sarıdag et al reported that cuspal coverage decreased the fracture resistance of the posterior tooth and lithium-disilicate glass-ceramic restoration complex. [28] Researchers also revealed that the teeth restored with zirconia ceramic inlays or onlays demonstrated similar fracture resistance from each other and also to that of intact teeth.…”

“…Fracture resistance of inlays and onlays may be influenced by the quantity of the dental structure removed. [28] Hence, in several studies, the fracture strength of the restorative materials for endodontically treated teeth has been evaluated in the inlay cavities without cuspal coverage. [16,19,27] Sarıdag et al reported that cuspal coverage decreased the fracture resistance of the posterior tooth and lithium-disilicate glass-ceramic restoration complex.…”