Background: Partial coverage concepts have met the main goal of conservative dentistry. Vonlays, which combine features of veneers and onlays, are a recent alternative to full coverage designs and overlay partial coverage restorations. This in vitro study was conducted to compare the fracture resistance of the newly introduced pressable zirconia-reinforced lithium silicate with pressable lithium disilicate ceramic and to determine the optimal preparation design for partial coverage on upper premolars.
Methods: Fifty-two duplicated epoxy resin dies were prepared following vonlay and overlay preparation guidelines. For each preparation (n = 26), the specimens were divided into two subgroups to be restored with lithium disilicate (IPS e.max Press) or zirconia-reinforced lithium silicate (Vita Ambria) (n = 13 each). Ceramic vonlays and overlays were bonded using dual cure resin cement, subjected to thermomechanical fatigue, and the load to fracture was tested by using a universal testing machine. The specimens were fractographically analyzed via scanning electron microscopy (SEM). The normality of the fracture resistance data was checked using the Shapiro‒Wilk test and Q‒Q plots, and two-way ANOVA was used to assess the effect of the type of preparation and ceramic material on the fracture resistance.
Results: The group of overlays restored with zirconia-reinforced lithium silicate showed the highest mean fracture load (1218.69 N), while the group of vonlays restored with lithium disilicate had the lowest mean fracture resistance (967.15 N). The effect of preparation design and material type on fracture resistance was significant for both factors, p = 0.003 and p < 0.0001, respectively. Different features of the fracture surfaces, such as arrest lines, hackles, and directions of crack propagation, were observed.
Conclusions: Zirconia-reinforced lithium silicate exhibited greater resistance to fracture compared to lithium disilicate, making it a potential substitute for partial coverage restorations. Additionally, the overlay showed superior fracture resistance when compared to the vonlay preparation design.
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http://dx.doi.org/10.1186/s12903-024-04809-2 | DOI Listing |
J Prosthodont
January 2025
The Office of Assistant Dean for Research, School of Dental Medicine, Medical Sciences Campus, University of Puerto Rico, San Juan, Puerto Rico.
Purpose: This study aimed to evaluate and compare the fracture resistance of long-span fixed provisional restorations fabricated using milling, three-dimensional (3D) printing, and conventional methods.
Materials And Methods: Sixty specimens were prepared, divided into four groups of 15 each, corresponding to four fabrication methods: computer-aided design and computer-aided manufacturing (CAD-CAM) milled provisional resins, 3D-printed provisional resins, 3D-printed permanent resins, and conventional bis-acryl restorations reinforced with wire. The specimens underwent a three-point bending test using a universal testing machine to measure fracture resistance, quantified as maximum force (in Newtons).
Bone
January 2025
The School of Public Health, North China University of Science and Technology, Tangshan, Hebei, China. Electronic address:
Objective: To investigate the association between the cumulative exposure to triglyceride-glucose index (cumTyG index) and fragility fractures in the general population.
Methods: This prospective cohort study analyzed active and retired employees of Kailuan Group who participated in three consecutive health examinations in 2006, 2008 and 2010, and were followed up until 31st December 2022. The cohort comprised 55,824 participants who met the inclusion and exclusion criteria and were grouped using the cumTyG index quartiles.
JMIR Rehabil Assist Technol
January 2025
Department of Occupational Therapy, Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada.
Background: Forearm, wrist, and hand impairments affect many individuals and impose a significant economic burden on health care systems. The FEPSim (flexion, extension, pronation, and supination) is designed for hand and wrist rehabilitation. It could become part of the standard care for upper extremity rehabilitation, aiming to improve range of motion, dexterity, and strength during therapeutic activities.
View Article and Find Full Text PDFJ Am Acad Orthop Surg
January 2025
From the Department of Orthopaedics (A. Mo and F. Mo), Medstar Georgetown University Hospital, Washington, DC, and the Department of Orthopaedic Surgery (S. Lockey), University of Virginia, Charlottesville, VA.
The posterior ligamentous complex (PLC) provides critical structural support in the thoracolumbar spine. Its role in resisting progressive flexion is particularly important at the thoracolumbar junction due to the transition from the rigid thoracic spine to the more mobile lumbar region. Each component of the PLC contains anatomic features that contribute to both the structure and function of the PLC as a whole.
View Article and Find Full Text PDFJ Dent Sci
January 2025
Department of Cariology and Endodontology, Peking University School and Hospital of Stomatology, Beijing, China.
Background/purpose: It remains unclear how the thickness and number of pulp-chamber lateral walls (PCLWs) affects fracture resistance in endocrown-restored teeth.
Materials And Methods: 64 mandibular molars were collected and randomly divided into eight groups (n = 8). In group C (control group), the teeth were untreated.
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