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Biological Fate of Nanoparticles
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
S. Parthasarathi, C. Anandharamakrishnan
The oral route of administration is considered to be the most common and accessible way of administrating nutraceutical formulations. The food digestion process is carried out in the gastrointestinal tract and it is composed of several sections which differ in their chemical and enzymatic compositions and pH (Figure 12.5). Mastication or chewing is the first step in food digestion, which reduces particle size and creates the food bolus. The oral cavity (mouth) is followed by the pharynx and esophagus, and the food bolus is conveyed to the stomach by a peristalsis process. The stomach is divided into four major regions: fundus, body, antrum, and pylorus, and it has three main motor functions: storage, mixing, and emptying. The proximal part of the stomach is fundus and body, which act as a reservoir for undigested food materials (Kong and Singh, 2008). The proximal part initiates contact between bolus and gastric juice. Gastric juice is mainly composed of enzymes, pepsin, and lipase, hydrochloric acid leading to a regular fall in pH (approximately from pH 6–5 to 1.5), promoting digestion. The distal part of the stomach is antrum and pylorus, responsible for grinding, mixing, and sieving solid food materials, and acts as a pump for gastric emptying by propelling actions. Gastric emptying conveys the food bolus into the small intestine, where absorption of nutrients takes place at more neutral or slightly basic pH values (Malhaire et al., 2016).
Finite element analysis in design of DMLS mandible implants
Published in Fernando Moreira da Silva, Helena Bártolo, Paulo Bártolo, Rita Almendra, Filipa Roseta, Henrique Amorim Almeida, Ana Cristina Lemos, Challenges for Technology Innovation: An Agenda for the Future, 2017
T.C. Dzogbewu, L. Monaheng, I. Yadroitsava, W.B. du Preez, I. Yadroitsev
The human mandible (lower jaw) is noted as the strongest bone of the skull and is capable of moving independently from the head movement. It supports the lower teeth and provides a place of attachment for the mastication muscles (Saladin 1998). The masseter muscle is the principal mastication muscle and is responsible for retracting and elevating the mouth (opening and closing of the mouth). It must be able to exert enough force for biting and chewing of food (Santana-Mora et al. 2014). The magnitude of the resultant force produced by the mastication muscles on the dental arches during clenching of the teeth in maximum intercuspation for normal humans ranges from 246.9 to 2091.9 N (Hattori et al. 2009). The resultant force during clenching of the teeth was found to act at an angle of approximately 69° to the occlusal plane. This is because the angle between the occlusal plane and the anterior boarder of the masseter muscle remains approximately 69° (Figure 2b, point D) based on the cephalogram analysis of Sato et al. (2007).
An approach for simultaneous reduction and fixation of mandibular fractures
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Ethan Snyder, Mohamed Trabia, Nir Trabelsi
There are four primary muscles attached to the mandible that aid in mastication: masseter, temporalis, medial pterygoid, and lateral pterygoid (Shayesteh Moghaddam et al. 2018) and (Lovald et al. 2010). Each of these muscles induce forces of varying magnitude and direction during speaking or eating. After a mandibular fracture, these muscles tend to either separate or reduce the fracture, depending on the fracture location and the direction of the muscle forces proximal to the fracture. Muscle forces corresponding to a right molar clench are listed in Table 1 (Korioth et al. 1992). These forces were scaled down to 60% of their original values to more accurately portray post-surgical loading (Tate et al. 1994). Each muscle group was associated with unit vector directions and a scale factor, depending on which side of the mandible the clench force was applied to. The locations of muscle forces and fixed supports were chosen based on (Korioth et al. 1992). While the muscle origins were symmetric on both sides of the mandible, the force vectors for the left side are asymmetrical across the YZ-plane, which is the mandible’s vertical plane of symmetry. Figure 9 presents a view of muscle force origins. These muscles are labeled A through E. Post-surgical muscle forces were used in the simulations.
Morphological analysis of the temporomandibular joint in patients with anterior disc displacement
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Tinghui Sun, Bingmei Shao, Desmond Y. R. Chong, Zhan Liu
Temporomandibular disorders (TMD) are the most common issues when it comes to our jaw joints, sensitive bi-condylar joints that connect the mandible to the skull and regulate jaw movements during mastication, speech, expression, etc. There is a high prevalence of TMD in adults and the symptoms vary from mild discomfort to painful temporomandibular joint (TMJ) dysfunction. It was reported that 25% to 30% of the population has at least one TMD symptom (Solberg et al. 1979; Rugh and Solberg 1985; Koh and Robinson 2004) and the overall prevalence of TMD in females was much higher than in males with ratios varying from 2:1 to 8:1 in the different surveys (Solberg et al. 1979; Ingawale and Goswami 2009; de Godoi Gonçalves et al. 2010; Martins-Junior et al. 2010). Despite the high incidence of TMD, only a small amount of the patients would seek medical help, for the symptoms are mild at the early stage and many of them can be relieved spontaneously.
A novel computational method to determine subject-specific bite force and occlusal loading during mastication
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
Oliver Röhrle, Harnoor Saini, Peter V. S. Lee, David C. Ackland
Chewing, and the resultant occlusal force generated between the maxillary and mandibular teeth, is achieved by the contraction of the masticatory muscles (Umesh et al. 2016), and occurs dynamically during normal mastication. Human bite force is known to vary along the dental arch (Ferrario et al. 2004). It is a highly subject-specific quantity, varying with gender (Miyaura et al. 1999; Varga et al. 2011), age (Peyron et al. 2004), weight (Shiau and Wang 1993), and ethnicity (Shinogaya et al. 2001), and is strongly connected with dental status and masticatory performance (Fontijn-Tekamp et al. 2000; Okiyama et al. 2003). The measurement of bite force is clinically relevant as it may be used to evaluate dentition, dentures, orthognatic surgery, temporomandibular joint function, as well assess the functional performance of prosthetic devices (Biswas 2013; Fernandes 2003).