Studies on the fracture performance of a recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate ceramic containing virgilite with different cements are lacking. The purpose of this in vitro study was to evaluate the fracture resistance of crowns made of a recently introduced chairside CAD-CAM lithium disilicate containing virgilite cemented with different types of adhesive luting cement. Sixty complete coverage crowns for a maxillary right central incisor were milled out of a lithium disilicate with virgilite (CEREC Tessera) (n=48) and a traditional lithium disilicate (e.max CAD) (n=12) using a chairside CAD-CAM system (Primescan). The central incisor tooth preparation included a 1.5-mm incisal reduction, a 1.0-mm axial reduction, and a 1.0-mm chamfer finish line. The restorations were bonded with different types of resin cement to 3D printed dies of the tooth preparation and were divided into 5 groups (n=12 per group): e.max CAD with Multilink Automix (E.Mu); Tessera with Multilink Automix (T.Mu); Tessera with Calibra (T.Ca); Tessera with Unicem (T.Un); and Tessera with Speedcem (T.Sp). The cemented restorations were stored in water for 30 days and then loaded until they were fractured in compression. The load at fracture was analyzed with a 1-way analysis of variance (ANOVA) and the honestly significant difference (HSD) Tukey test (α=.05). The mean fracture resistance of traditional lithium disilicate and virgilite lithium disilicate anterior crowns significantly differed depending on the type of resin cement used (P<.05). Group E.Mu displayed the highest values (946.35 ±155 N), followed by group T.Un (819.59 ±232 N), group T.Sp (675.52 ±153 N), and group T.Mu (656.95 ±193 N). The lowest values were displayed by group T.Ca (567.94 ±184 N). The fracture resistance of lithium disilicate containing virgilite and traditional lithium disilicate crowns cemented with the same cement displayed statistically similar values. However, significant differences were observed when the virgilite lithium disilicate crowns were cemented with different types of adhesive luting cement. The crowns in the T.Ca group displayed the lowest fracture resistance.

Background: Determination of the eligibility of several tooth analog materials for use in crown fracture testing. Methods: A standardized premolar crown preparation was replicated into three types of resin dies (C&B, low modulus 3D printed resin; OnX, high modulus 3D printed resin composite; and highest modulus milled resin composite). 0.8 mm zirconia crowns were bonded to the dies and the maximum fracture load of the crowns was tested. Twelve extracted human premolars were prepared to a standardized crown preparation, and duplicate dies of the prepared teeth were 3D printed out of C&B. Zirconia crowns were bonded to both the dies and natural teeth, and their fracture load was tested. Results: There was no statistical difference between the fracture load of zirconia crowns bonded to standardized dies of C&B (1084.5 ± 134.2 N), OnX (1112.7 ± 109.8 N) or Lava Ultimate (1137.5 ± 88.7 N) (p = 0.580). There was no statistical difference between the fracture load of crowns bonded to dentin dies (1313 ± 240 N) and a 3D-printed resin die (C&B, 1156 ± 163 N) (p = 0.618). Conclusions: There was no difference in the static fracture load of zirconia crowns bonded to standardized resin dies with different moduli or between a low modulus resin die and natural dentin die.

The existing scientific literature lacks comprehensive information regarding the influence of zirconia crown height on debonding and fracture of the ceramic restorations on titanium base abutments. Additionally, there is a lack of comparative studies evaluating different types of zirconia as restorative options for screw-retained restorations. Purpose: The purpose of this study was to assess the fracture strength and the failure modes of the zirconia crown/titanium abutment complex by investigating the impact of increasing the height of zirconia crown and comparing different types of zirconia (3 mol% yttria-stabilized zirconia and translucent 5 mol% yttria-stabilized zirconia). Materials and Methods: Six groups of 10 specimens in each group were fabricated. Three groups of specimens (groups # 1, 2, and 3) were fabricated from 3Y zirconia in corresponding heights of 8, 10, and 12 mm. Three more groups (groups # 4, 5, and 6) were fabricated from 5Y zirconia in the same heights (8, 10 and 12 mm). All copings were bonded to 4 mm high titanium base abutments using dual-polymerization resin cement. The specimens underwent load cycling of 100,000 cycles with a force of 100 N. Subsequently, the specimens were loaded to compression until fracture and the failure mode was visually evaluated. Results: Statistically significant differences in fracture strength were noted among all tested groups. Conclusions: 3Y zirconia showed increased strength compared to 5Y in all heights. Ceramic copings with lower height showed increased strength compared to higher copings in both tested zirconia materials.