Objective: Minimal invasive endodontics preserve coronal and radicular tooth structure to increase the fracture resistance of teeth. The aim of this study was to assess the influence of final preparation taper on the fracture resistance of maxillary premolars.
Materials And Methods: Sixty maxillary premolars were selected and divided into 2 groups: 30 were shaped with a final apical diameter 30 and a 4% taper and 30 with 6% taper using iRaCe instrument (FKG dentaire, Switzerland). All root canals were irrigated with sodium hypochlorite and final rinse with ethylenediaminetetraacetic acid. All canals were filled with gutta-percha single-cone filling technique and AHPlus sealer (Dentsply- Maillefer, Baillagues, Switzerland) and access cavity restored with resin composite. Roots were wax coated, placed in an acrylic mold and loaded to compressive strength fracture in a mechanical material testing machine recording the maximum load at fracture and fracture pattern (favorable/restorable or unfavorable/unrestorable). Fracture loads were compared statistically, and data examined with Student -test with a level of significance set at ≤ 0.05.
Results: No statistically significant difference was registered between the 4% taper of preparation (270.47 ± 90.9 N) and 6% taper of preparation (244.73 ± 120.3 N) regarding the fracture resistance of the endodontically treated premolars tested ( = 0.541), while more favorable restorable fractures were registered in the 4% taper group.
Conclusions: Continuous 4% preparation taper did not enhance the fracture resistance of endodontically treated maxillary premolars when compared to a 6% taper root canal preparation. More fractures were registered in the 4% taper group.
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http://dx.doi.org/10.4103/jispcd.JISPCD_88_18 | DOI Listing |
Nat Commun
January 2025
Institute of Innovative Materials, Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen, China.
Natural materials with highly oriented heterogeneous structures are often lightweight but strong, stiff but tough and durable. Such an integration of diverse incompatible mechanical properties is highly desired for man-made materials, especially weak hydrogels which are lack of high-precision structural design. Herein, we demonstrate the fabrication of hierarchically aligned heterogeneous hydrogels consisting of a compactly crosslinked sheath and an aligned porous core with alignments of nanofibrils at multi-scales by a sequential self-assembly assisted salting out method.
View Article and Find Full Text PDFBMC Oral Health
January 2025
Department of Conservative Dentistry, Faculty of Dentistry, Alexandria University, Alexandria, Egypt.
Background: Conservative dentistry introduced modern restoration designs, contributing to the greater use of partial-coverage ceramic restorations. New strong bondable ceramic materials made fabricating partial coverage ceramic restorations easier to restore the badly destructed teeth.
Aim Of The Study: This study investigated the impact of three distinct overlay preparation designs on the marginal fit (both before and after thermal aging) and the fracture resistance of overlay restorations fabricated using advanced zirconia-reinforced lithium disilicate (ALD) CAD/CAM glass-ceramic blocks.
J Orthop Surg Res
January 2025
Department of Orthopedics, Beijing Chaoyang Hospital, Capital Medical University, 8 Gongren Tiyuchang Nanlu, Chaoyang District, Beijing, 100020, China.
Background: Finite element analysis (FEA) could advance the understanding of fracture fixation and guide the choice of surgical treatment. This study aimed to compare two internal fixation methods in the treatment of displaced proximal humeral fracture (PHF) through FEA.
Methods: Three-dimensional FEA model based on the left shoulder joint of a 67-year-old female patient with PHFs and osteoporosis was adopted, in order to analyze the fixation effect and load stress distribution of internal fixation plates with open reduction and intramedullary nails without opening the fracture in the treatment of Neer III-VI PHF.
PLoS One
January 2025
Lawrence Livermore National Laboratory, Physical and Life Science Directorate, Livermore, CA, United States of America.
Post-traumatic osteoarthritis (PTOA) is a painful joint disease characterized by the degradation of bone, cartilage, and other connective tissues in the joint. PTOA is initiated by trauma to joint-stabilizing tissues, such as the anterior cruciate ligament, medial meniscus, or by intra-articular fractures. In humans, ~50% of joint injuries progress to PTOA, while the rest spontaneously resolve.
View Article and Find Full Text PDFPLoS One
January 2025
Division of Periodontics, Department of Diagnosis and Surgery, UNESP, São Paulo State University "Júlio de Mesquita Filho", Araçatuba, Brazil.
The study aimed to evaluate the potential protection against fractures of oral Q10 supplementation in the tibias of rats exposed to nicotine. Nicotine is known to negatively impact bone density and increase the risk of fractures, in addition to affecting other systems such as the gastrointestinal system, impairing its absorption capacity, negatively affecting bone health. To investigate this, eighty male rats were divided into four groups (n = 20) receiving either nicotine hemisulfate or saline solution (SS) for 28 days.
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