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Gear couplings are usually machined using hob and slotting cutter in a predetermined circular path. The tool feed path determines tooth profile. This article designs a new feed path. A new mathematical model of tooth surface is constructed based on path and tooth profile parameters. Calculation method for minimum normal design clearance is proposed, and furthermore, theoretical model for the clearance under misalignment conditions is developed. The calculation of the tooth surface coordinates and minimum clearance in the circumferential direction, the distribution of the minimum clearance in the circumferential is studied under the new path. The clearance of the tooth surface and circumferential direction are obtained, and the contact characteristics of teeth in the circumferential direction are analyzed. The results show that the new path can reduce the dependence of misalignment angle on clearance and tooth width compared to conventional path. A high load-carrying contact with full involute is more easily achieved on the tooth surface, and the load-carrying performance are more evenly distributed across the teeth.
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http://dx.doi.org/10.1038/s41598-024-79365-4 | DOI Listing |
J Clin Periodontol
September 2025
Department of Oral Medicine and Periodontology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia.
Background And Objective: Traditional and planimetric plaque indices rely on plaque-disclosing agents and cannot quantify three-dimensional (3D) structures of dental biofilms. We introduce a novel computer-assisted method for evaluating and visualising plaque volume using intraoral scans (IOSs).
Materials And Methods: This was a 4-day, non-brushing, plaque-regrowth study (n = 15).
Dent Mater J
September 2025
Biomaterials Lab, Dentistry School, Federal University of Pará.
This study evaluated the chemical profile of toothpastes (TPs) and mouthrinses (MRs) and their effects on tooth enamel ultrastructure, and the viability of human dental pulp fibroblasts (hDPF). Four TPs and MRs containing different remineralizing agents (arginine, potassium nitrate, pro arginine, and stannous chloride) were analyzed for pH, titratable acidity (TA), and ion concentrations (Ca, K, Na). Enamel ultrastructure was evaluated using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM).
View Article and Find Full Text PDFJ Dent
September 2025
Department of Restorative Dentistry, Faculty of Dentistry, Malaya University, Kuala Lumpur, Malaysia. Electronic address:
Objectives: to evaluate the effect of smear-layer deproteinization using papain gel and SPRG-adhesive on marginal-gap, anti-demineralization of enamel and dentin after chemical pH cycling and assess acid-base resistance zone (ABRZ) characteristics.
Methods: Cylindrical cavities were prepared cervically in thirty-two extracted premolars. Teeth were divided into two pretreatment groups (n=16); deproteinization with papain enzyme gel (Papacarie Due, Brazil) for 60 second, and no-deproteinization.
J Esthet Restor Dent
September 2025
Department of Prosthodontics, Seoul National University School of Dentistry, Seoul, Republic of Korea.
Objective: To evaluate the impact of occlusion type and artificial intelligence-based computer-aided design (CAD) software on the geometric accuracy and clinical quality of auto-generated anterior and posterior crown designs.
Methods: Five typodont models representing various occlusion types (normal, Class I anterior diastema, Class II division 1, Class II division 2, and Class III anterior crossbite occlusion) underwent crown preparation for the maxillary right central incisor and first molar. Ten sets of intraoral scans were obtained from each prepared model, and crown designs were automatically generated using two software programs: deep learning-based (DL; Dentbird) and conventional automated (CA; Auto Workflow, 3Shape) (n = 10).
F1000Res
September 2025
Associate professor, Department of Conservative Dentistry and Endodontics, Sharad Pawar Dental College, Datta Meghe Institute of Higher Education and Research, Sawangi, wardha, Maharashtra, 442001, India.
One of the common forms of dental injury is anterior crown fractures, which mainly affect teenagers and young adults. Fractures of the coronal portion of the permanent incisors characterize 18-22% of total traumatic injuries to dental hard tissues, of which 96% of them comprise the maxillary incisors. An uncomplicated fracture of the crown is one of the most common types of dental traumatic injury.
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