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Computational analysis for stress intensity factor (KI) measuring in metal-ceramic interface
Published in J. Belinha, R.M. Natal Jorge, J.C. Reis Campos, Mário A.P. Vaz, João Manuel, R.S. Tavares, Biodental Engineering V, 2019
Elza M.M. Fonseca, Joana F. Piloto, Maria G. Fernandes, R.M. Natal Jorge
Metals, alloys, ceramics and others materials have been used in dentistry as restorative materials. Metal and ceramic restorations are widely used in dentistry. Nevertheless, restorations fracture usually occurs and the incidence of porcelain fracture was the second most common cause of metallic-ceramic fixed partial denture replacement (Rola et al. 2013). The interface between metal and ceramic is often the weakest point of these devices. Different technical factors, as geometric, metal design, porcelain thickness, material defects, material compatibility, technique fixation, are the most important matters in contributing to the formation of internal or external cracks (Ismail 2014), (Rola et al. 2013). However, a challenging aspect in ceramic materials is their restricted loading capability due to the low fracture toughness (Qing Li et al. 2006). This has become a most important problem limiting the use of ceramic materials to completely replace metals in dental restorations (bridges), where the level of tensile stress is higher (Qing Li et al. 2006). It would be desired if the crack initiation can be anticipated and evaluated prior to the bridge construction, thus providing criteria for an improved design (Qing Li et al. 2006).
Dentistry in medical history
Published in Marshall Joseph Becker, Jean MacIntosh Turfa, The Etruscans and the History of Dentistry, 2017
Marshall Joseph Becker, Jean MacIntosh Turfa
Ambroise Paré (1510–1590), often considered the founder of modern surgery (his knowledge of anatomy was augmented through extensive battlefield experience), was also involved in the production of dental appliances. His position as chief surgeon at the Hotel Dieu, the foremost hospital in Paris, and later as chief surgeon to the French kings, rendered his publications highly influential. From his origins as a humble barber’s apprentice he must have learned a great deal about basic dental extractions before expanding his surgical activities. His text De Chirurgie (Paré 1564: 218) includes a figure that is labeled “Dentz artificielles faittes d’os, qui s’attachent par vn fil d’argent en lieu des autres qu’on aura perdues” (“artificial teeth made of bone, which are attached by a silver wire to replace those which have been lost”) (see Figure 1.5). He illustrates five examples that are alike except for the number of teeth held within a base (see also Hoffmann-Axthelm 1970: fig. 8). Paré combined silver wire and other attachment techniques to produce a fixed partial denture that appears to have had at least some masticatory functions.
Marginal gap and fracture resistance of CAD/CAM ceramill COMP and cerasmart endocrowns for restoring endodontically treated molars bonded with two adhesive protocols: an in vitro study
Published in Biomaterial Investigations in Dentistry, 2020
Israa Atif Kassem, Ibrahim Elsebai Farrag, Samir Mahmoud Zidan, Jylan Fouad ElGuindy, Reham Said Elbasty
There was no statistical difference between the fracture resistances of the two materials after thermo-mechanical loading. The mean fracture loads recorded in this study were 2420 N for the Ceramill COMP endocrowns and 2220 N for the Cerasmart endocrowns, both of which are far greater than the maximum chewing and biting loads previously reported by Anderson[47], who measured the loads acting on mandibular molars using strain gauges and found that the maximum whole-tooth load varied between 7.2 and 14.9 kg (70.6 and 146 N) when eating meat, biscuits, or carrots. De Boever et al.[48] determined that the normal chewing forces exerted on the occlusal surfaces of teeth seldom exceeded 2.4 and 7.2 kg (23.5 and 70.6 N) by using transmitters in a removable fixed partial denture, and concluded that functional chewing forces vary from session to session and with the consistency and viscosity of the food. More recently, the maximum biting forces on the first molar were reported to be approximately 859 N[49] and 878 N,[50] whereas the mean maximum bite force varied significantly, ranging from 234 to 597 N in females and from 306 to 847 N in males.[51] No matter the bite force used, both endocrown materials can clearly accept the applied load without fracture.
Biomechanical evaluation of 3-unit fixed partial dentures on monotype and two-piece zirconia dental implants
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Jefferson David Melo de Matos, Guilherme da Rocha Scalzer Lopes, Leonardo Jiro Nomura Nakano, Nathália de Carvalho Ramos, John Eversong Lucena de Vasconcelos, Marco Antonio Bottino, João Paulo Mendes Tribst
Then, the model of the section of the jaw received two cilindrical implants at the cortical bone level according to the system of each group (regions of first premolar and first molar). A three-unit fixed partial denture was cemented over the implants (first premolar, second molar and first molar). To simulate the clinical condition according to the literature (Kohal et al. 2013; Roehling et al. 2015), a thin layer of 0.3 mm thick resin cement was added (Dal Piva et al. 2017), as shown in Figure 1.