This study evaluated the mechanical behavior and risk of failure of three CAD-CAM crowns repaired with different resin composites through a three-dimensional (3D) finite element analysis. Three-dimensional models of different cusp-repaired (conventional nanohybrid, bulk-fill, and flowable resin composites) crowns made of zirconia, lithium disilicate, and CAD-CAM resin composite were designed, fixed at the cervical level, and loaded in 100 N at the working cusps, including the repaired one. The models were analyzed to determine the Maximum Principal and Maximum Shear stresses (MPa). Complementary, an in vitro shear bond strength test ( = 10) was performed to calculate the risk of failure for each experimental group. The stress distribution among the models was similar when considering the same restorative material. The crown material affected the stress concentration, which was higher for the ceramic models (±9 MPa for shear stress; ±3 MPa for tensile stress) than for the CAD-CAM composite (±7 MPa for shear stress; ±2 MPa for tensile stress). The shear bond strength was higher for the repaired CAD-CAM resin composite (±17 MPa) when compared to the ceramics (below 12 MPa for all groups), while the repair materials showed similar behavior for each substrate. The stress distribution is more homogenous for repaired resin composite crowns, and a flowable direct resin composite seems suitable to repair ceramic crowns with less risk of failure.
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http://dx.doi.org/10.3390/dj11110254 | DOI Listing |
J Esthet Restor Dent
January 2025
Magne Education, Beverly Hills, California, USA.
Objective: Chemicals used during canal disinfection and endodontic sealers have a deleterious effect on dentin bond strength. The aim of this study was to evaluate a novel clinical sequence to improve the resin-dentin microtensile bond strength (μTBS) to endodontically treated teeth.
Materials And Methods: Twenty human molars were distributed in four experimental groups (n = 5, N = 20): C-control group without exposure to any endodontic chemical substances (2.
Dent Mater
January 2025
KU Leuven, Department of Oral Health Sciences, BIOMAT & UZ Leuven, Dentistry, Kapucijnenvoer 7, 3000 Leuven, Belgium. Electronic address:
Objectives: To evaluate the effect of different zirconia compositions and manufacturing processes on the light irradiance (LI), to measure the degree of conversion (DC) of solely light-curing restorative composite underneath these zirconia grades and to evaluate the respective zirconia microstructures.
Methods: Six dental zirconia grades (GC HT, GC UHT [GC]; Katana HT, Katana UTML [Kuraray Noritake]; Lava Esthetic, Lava Plus [3 M Oral Care]) were cut and sintered per manufacturer instructions. One 3D-printed zirconia grade (XJet [XJET]) was prepared according to previous research.
Dent Mater
January 2025
Minnesota Dental Research Center for Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN, USA. Electronic address:
Objective: This study compared the fracture load, stress distribution, and survival probability under cyclic loading of extensively restored teeth treated with multisonic irrigation with those treated with conventional instrumentation, with or without a post.
Methods: Mesial-occlusal-distal cavities were prepared in 30 human mandibular premolars. The teeth were randomly divided into 3 groups of 10 based on the endodontic and restorative procedures: (1) Root canal treatment (RCT) followed by resin composite restoration (control group), (2) RCT followed by a glass fiber post restoration (conventional group), and (3) minimal instrumentation plus multisonic irrigation followed by resin composite restoration (GW group).
Eur J Dent
December 2024
Department of Conservative Dentistry, Faculty of Dentistry, October University for Modern Sciences and Arts, Giza, Egypt.
Objective: Continuous advancements in composite resin materials have revolutionized and expanded its clinical use, improving its physical and mechanical properties. Attaining and retaining surface texture and gloss are crucial for the long-term durability of the composite resin material. This study investigated the supra-nanospherical filler composite material compared with different composite resin materials immersed in different beverages.
View Article and Find Full Text PDFBMC Oral Health
January 2025
Department of Endodontics, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
Background: The fracture of an endodontic instrument within the root canal system can occur during root canal therapy, complicating thorough cleaning and shaping. Consequently, managing the broken fragment becomes crucial.
Methods: Eighty Nickel-titanium (NiTi) #20 K-files (Mani, Tochigi, Japan) were cut 8 mm from the tip, fixed into a corkboard, and classified into five groups (n = 14 each).
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