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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).
Finite element analysis of 3D-printed personalized titanium plates for mandibular angle fracture
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Yan Li, Hui Li, Qingguo Lai, Runqi Xue, Kaiwen Zhu, Yanwei Deng
Setting freedom constrains on the anatomical attachment points of the mandibular temporal muscle, masseter muscle, medial pterygoid muscle and lateral pterygoid muscle, ignoring the surrounding attachment ligaments and smaller muscles of the mandibular (Sun et al. 2004). The muscle strength is 1/2 of the maximum occlusal force and decomposed according to the coordinate axis (Quiroga and Garcia 2003; Thresher and Saito 1973) by simulating central occlusion and healthy side molar occlusion (Figure 5). The specific occlusal force is shown in Table 2.
Detection of lower jaw activities from micro vibration signals of masseter muscles using MEMS accelerometer
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2023
Such studies in the literature are important in terms of diagnosing bruxism, especially since lower jaw activities can be seen in healthy individuals during sleep. Not every activity during sleep indicates the presence of bruxism. Diagnosis of bruxism is difficult since not all contractions of masticatory muscles during sleeping are bruxism episodes. However, these methods are complicated by the use of different sensor structures to detect bruxism, especially during sleep, and require a clinical laboratory environment with expert evaluation. Thus, it is costly and time consuming. Therefore, considering these negativities in our previous studies, bruxism diagnosis could be made most effectively based on EMG measurements only by using wavelet entropy transform, autoregression and artificial neural network (Sonmezocak et al. 2021a). When only sEMG method is considered, there are some disadvantages that affect the accuracy of these signals. The most important factor is the signal-to-noise ratio (SNR) because sEMG signals are amplified in order to be processed. When the signal is amplified, any existing noises are also amplified (Pan et al. 2020). Another disadvantage is the interference caused by electromyographic signals from neighboring muscles. Moreover, change in skin impedance due to factors such as not fully contacting the sEMG probes to the skin, sweatiness of the skin and excessive skin thickness may cause faulty measurement, and this in turn may lead to faulty classification (Pan et al. 2020; Tankisi et al. 2020). Therefore, in this study, by obtaining electrical signals from micro vibrations in the masseter muscle on the ‘z’ vertical axis (Figure 1) of the MEMs-based accelerometer, lower jaw movements can be effectively determined in the diagnosis and treatment of bruxism without using an external amplifier unit. In this system, the gyroscope sensor, which works depending on gravity, was not used due to the change in the lying position of the patients during sleep.