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Biomechanics of EatingStudies

Display system of jaw movement Grinding and chopping motion of teeth Structure of mandible Patient-specific stress analysis Structure of snack food Dynamic characteristics of head in eating Statistical analysis by onomatopoeia

Please click the research themes for detail descriptions.
(Some parts are in preparation.)

Eating is one of the most essential behaviors in our life. It has several significant meanings more than a process of intake of nutrition to our body. That is, eating is a pleasure itself as implied by the words "food culture" or "gastronomic culture".

Vigorous chewing is especially important for elderly people because it directly leads to life worth living. We are studying subjects about "eating" from biomechanical viewpoints as shown in the figure. We represent the research project "biomechanics of 食" using one Kanji character denoting eating. The comprehensive approach will reveal new knowledge about eating and contribute to quality of life (QOL).

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Display system of jaw movement
The display system visually presents mandibular movement of a patient as moving image from an arbitrary direction with mouse operation. It also presents a motion trajectory at specified point as well as the velocity profile. It makes a medical doctor easy medical diagnosis of TMD (Temporomandibular disorders) as well as the patient easily understands his symptom. The system is realized by integration of two techniques, patient-specific modeling and precise motion capture.


【Literature】
Kiwamu SAITOU, Norio INOU, Hitoshi KIMURA, Taisei FUJIKAWA, Naoki OGAWA and Koutarou MAKI:
Synthesis of Mandibular Movements from Basic Motion Modes Considering Dynamic Profile of Masticatory Muscles,
Journal of Biomechanical Science and Engineering Vol.7 No.22, pp.223-236 (2012)
Kiwamu Saitou,Hitoshi Kimura,Norio Inou,Koseki Mitihiko,Taisei Fujikawa,Yuusuke Asama,Naoki Ogawa,Koutarou Maki:
DEVELOPMENT OF 3-D MOTION DISPLAY SYSTEM TO ASSIST DIAGNOSTIC TREATMENT OF OCCLUSAL DISORDER,
The First IFToMM Asian Conference on Mechanism and Machine Science (2010), 250098
Michihiko KOSEKI, Akira NIITSUMA, Norio INOU and Koutarou MAKI:
Three-dimensional Display System of Individual Mandibular Movement,
Complex Medical Engineering, Springer, pp.117-127 (2007)
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Grinding and chopping motion of teeth
The human mandible skillfully masticates foods with complex movement. Chopping and grinding motions play important rule to effective mastication. However, there is no study to visualize these motion profiles including teeth configuration. This study challenges the subject with a hybrid model. The hybrid model is composed of bone models made from cone-beam X-ray CT data of the patient and a precise teeth model based on patient's plaster teeth model. The hybrid model presents detailed motion trajectories that a mandible moves along teeth configuration in grinding motion. The function of teeth guidance has been pointed out in the dental field, but this is the first time that we can observe the movement as the concrete movement.


Trajectories of lower molar   

【Literature】
Kiwamu Saitou, Hitoshi Kimura, Norio Inou, Taisei Fujikawa, Youhei Takeuchi and Koutarou Maki: Development of 3-D Motion Display System to Assist Diagnostic Treatment o Occulusal Disorder (Contact State Analysis of Upper and Lower Teeth with Patient-Specific Hybrid Model), Transactions of the Japan Society of Mechanical Engineers, Series C, Vol. 79, No.807, pp.4121-4130, (2013) (in Japanese)
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Structure of mandible
Animal's mandible takes a different shape. The shape seems to be designed according to biting function. We challenged the subject by the cellular automaton model. The cellular automaton is useful to find a proper structure that satisfies a fully stresses design. We give four mechanical biting conditions according to a human and a rat to the initial rectangular shape. Computer simulations of structural formation showed similar shapes of actual mandibles.


     Human mandible Rat mandible     Structural formation of
                                 a rat mandible



  Structural formation of a rat mandible


  Simulation result (left) and an actual rat mandible (right)


  Estimated biting conditions of a rat


【Literature】
Norio INOU, Michihiko KOSEKI, Ichiro KATO and Koutarou MAKI:
Structural Formation of Mandibles by a Cellular Automaton Model, Design and Nature II, WIT Press, pp.265-274, 2004
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Patient-specific stress analysis
Patient-specific mechanical simulation has a potential to make a meticulous medical treatment for each patient. For example, it is useful for surgical planning of a mandible or implant of tooth considering mechanical states. Patient-specific simulation of the human mandible needs two techniques, individual modeling method and estimation of masticatory forces during biting.

   
【Literature】
Norio INOU, Michihiko KOSEKI and Koutarou MAKI:
Patient Specific Finite Element Modeling of a Human Skull,
Advances in Science and Technology, Vol.49, pp.227-234(2006)
Norio INOU, Michihiko KOSEKI, Hiroyuki TANIZAKI and Koutarou MAKI:
Development of the Support System for Individual Stress Analyses of a Bone, Computer Methods in Biomechanics & Biomedical Engineering - 5, 109A(CD-ROM), 2005
N.Inou, Y.Iioka, H.Fujiwara and K.Maki:Functional Adaptation of Mandibular Bone,Computational Biomechanics, K.Hayashi, H.Ishikawa (Eds) Springer-Verlag, pp.23-42, (1996)
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Structure of snack food
Japan has variety of snack foods. People enjoy variety of food textures in eating them. It is important for evaluation of food texture to know material properties of the foods. There are few reports focusing on the microstructure though it is essential to estimate the substantial mechanical properties.

We developed a novel method to measure substantial Young's modulus focusing on the microstructure. This method uses a micro-scale compression test for small test piece and a finite element analysis. Measured material Young's moduli are 18 to 170 times larger than traditional values obtained with the simple compression test.

 
Sectional images of snack foods 

   
Micro-load testing machine

【Literature】
Ren Kadowaki, Norio Inou, Hitoshi Kimura:
Measurement of Microscopic Young's Modulus of Crispy Foods, International Proceedings of Chemical, Biological & Environmental Engineering, Vol.50, pp79-83 (2013)
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Dynamic characteristics of head in eating
This study deals with food texture of crispy foods focusing on two types of chewing sounds in eating snack foods, which are air conduction sound and bone conduction sound. The two types of sounds were analyzed by FFT and power spectra were obtained. Finite element models were also applied for examining vibration characteristics of human skull. The computational results of modal analysis show that size of human skull affects bone conduction sound, which was identified as different power spectra from experimental data of an adult and a child. These results suggest that biomechanical factor of skull affects eating quality of foods.

Adult

 Child

【Literature】
 Ren KADOWAKI, Norio INOU, Hitoshi KIMURA,
 "Effect of Vibration Characteristics of Skull in Mastication of Crispy Foods
 on Food Texture"
,
 Journal of Medical and Bioengineering, Vol.2, No.3&No.4, pp.186-190(2013)  
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Statistical analysis by onomatopoeia
There is a lot of onomatopoeia words in Japanese. They seem to present physical sounds with a repetitive word faithfully such as "sakusaku", "karikari", "paripari" and "garigari". These words are useful to evaluate food textures of crispy snack foods. We compared these words to microstructure of foods with a statistical analysis.

【Literature】
Ren KADOWAKI, Norio INOU, Hitoshi KIMURA:
Relationships between Food Textures Presented Using Onomatopoeia and Inner Structures of the Snacks,
Journal of Japanese Society for Masticatory Science and Health Promotion 22(1), 36-43, (2012)(in Japanese)