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Chewing Movement (chewing + movement)
Selected AbstractsInfluence of gum-chewing on the haemodynamics in female masseter muscleJOURNAL OF ORAL REHABILITATION, Issue 4 2009N. ABE Summary, Blood flow in active skeletal muscles provides energy substrate, oxygen and reduction of excessive heat and metabolic by-products. Although cyclic jaw motions such as those during mastication and speech articulation are the primitive oro-facial functions, possible effects of the cyclic muscle contractions on the intramuscular haemodynamics of the jaw muscles remains scarcely known. We investigated the masseteric haemodynamics during and after gum-chewing. Ten healthy female adults participated in the study. Electromyography, kinetics of masseter muscle oxygenation, electrocardiogram and blood pressure were recorded simultaneously. The subjects were asked to perform gum-chewing and cyclic jaw motion without gum bolus (empty-chewing task). The haemodynamics parameters were compared between the two experimental conditions. During gum-chewing task, deoxygenated haemoglobin and sympathetic nerve activity increased, while tissue blood oxygen saturation decreased. Blood pressure and parasympathetic nerve activity did not change. The overall behaviour of haemodynamic parameters during empty-chewing task was similar to that observed during gum-chewing task. However, the latency periods from the end of chewing until significant changes in the haemodynamic parameters were notably shorter (P < 0·05) in gum-chewing task as compared with those associated with empty-chewing task. The duration of the changes was shorter with empty-chewing than with gum-chewing. Fluctuations in masseter muscle haemodynamics associated with chewing jaw movement differed depending on the level of muscle contraction during movement. The differences became statistically significant immediately after the commencement of chewing and after the cessation movement. During the chewing movement, automatic nerve activities increased in response to the level of muscle contraction during movement. [source] Chewing-side determination of three food texturesJOURNAL OF ORAL REHABILITATION, Issue 1 2006J. PAPHANGKORAKIT summary, Food texture affects chewing movement but it is not known if it also affects the chewing-side pattern. This study determined the chewing sides of three test foods with different textures during habitual chewing. Twenty healthy dental students (aged 20,24 years) chewed pieces of pork jerky, fresh asparagus and almonds on two separate sessions (1 week apart). In each session, each subject chewed 30 food specimens, 10 of the same food type, until swallowing while a video camera recorded the displacement of the chin with respect to the other two reference points vertically marked along the facial midline. A slow-speed video playback was used to identify the chewing side of each cycle. The chewing-side pattern (right preference, left preference, no preference) in each individual was determined statistically. The results showed that overall, 11 subjects did not have any side preference whereas six and three subjects preferred to chew on right or left sides respectively. The chewing-side pattern remained unchanged between three food types in about half of the subjects. When the same food was compared between 2 days, the chewing-side pattern of almonds was shown to be most reproducible (18 subjects). Unidentified cycles with little or no lateral displacement, labelled as bilateral, were observed more frequently near the end of the chewing sequence with more occurrences in almonds and jerky than asparagus (P < 0·01). It was suggested that chewing-side preference is not a fixed characteristic. Food texture seemed to influence the side preference and also the occurrence of bilateral cycles. [source] Characteristics of the gum chewing occlusal phase in children with primary dentitionJOURNAL OF ORAL REHABILITATION, Issue 5 2004I. Saitoh Summary, Understanding of the growth and development of mandibular function is indispensable to the diagnosis of functional disturbances during childhood. The purpose of this study was to clarify the characteristics of the occlusal phase during gum chewing in children with primary dentition. Chewing motion at the working molar of 14 children with primary dentition and 28 female adults was recorded optoelectrically, and the frontal and sagittal angles of their closing and following opening strokes were measured and compared. In children the closing strokes were entered more vertically and anteriorly than in adults, and the opening strokes shifted to the non-working side in adults but moved to the working side in children. The degree of variance also differed between the two groups; the variance of the frontal angle was larger than that of sagittal angle in adults, but the opposite was true in children. These results suggested that the chewing pattern in children during the occlusal phase is distinctly different from adults and the chewing movement in children is not always less stable than in adults. [source] Length of the occlusal glide during chewing in children with primary dentitionJOURNAL OF ORAL REHABILITATION, Issue 11 2003H. Hayasaki summary, Chewing is one of the most important functions of the mandible, but, to date, there are very few studies of this function in children. The purpose of this study was to quantify the length of the occlusal glide at the lower incisal point during gum chewing in children with primary dentition. Eleven girls with primary dentition were selected for this study. Mandibular excursions with occlusal contacts and gum chewing movement were measured using an optoelectronic system that can measure mandibular movement with six degrees-of-freedom at a sampling frequency of 100 Hz. A curved mesh diagram of incisor coordinates during mandibular excursions was established to calculate the length of the occlusal glide for each subject. The occlusal glide lengths of children were compared with previously reported results for adults. The estimated length of the occlusal glide during closing was significantly shorter in children than in adults, contrary to that during opening. This result suggests that children have a characteristic chewing pattern that differs from adults. [source] Enamel ridge alignment in upper molars of ruminants in relation to their natural dietJOURNAL OF ZOOLOGY, Issue 1 2010T. M. Kaiser Abstract Although it is generally thought that dental design reflects mechanical adaptations to particular diets, concrete concepts of such adaptations beyond the evolution of hypsodonty are largely missing. We investigated the alignment of enamel ridges in the occlusal molar surface of 37 ruminant species and tested for correlations with the percentage of grass in the natural diet. Independent of phylogenetic lineage, species that were either larger and/or included more grass in their natural diet showed a higher proportion of enamel ridges aligned at low angles to the direction of the chewing stroke. Possible explanations for this design are a potential alignment of grass blades in parallel to the molar tooth row, a potential increased proportion of a propalinal (anterior,posterior) chewing movement in grazers as opposed to a strictly transversal chewing stroke in browsers and the general distribution of forces along the occlusal surface during the chewing stroke. The latter will be less heterogenous (with less force peaks) with an increasing proportion of low-angle enamel ridges. While the validity of these explanations will have to be tested in further studies, the enamel ridge alignment represents a clear signal that deviates from an arbitrary distribution and hence most likely represents a functional adaptation. [source] An Overview of Complete Artificial Fixed Dentition Supported by Endosseous ImplantsARTIFICIAL ORGANS, Issue 1 2005Dennis Flanagan Abstract:, The construction of a complete restoration of the dentition by the surgical placement of endosseous titanium implants that support a fixed prosthesis in each jaw is possible. The positionings of the implants and teeth in the prostheses are important factors for a successful long-term result. Distribution of the occlusal biting forces over as many implants as possible is important. Off-axial occlusal biting forces should be diverted to the anterior jaws where the forces are not as great. The posterior teeth should be designed with flat occlusal surfaces that separate during excursionary mandibular chewing movements. Medial mandibular flexure caused by the contraction of the medial pterygoid muscle can be addressed by constructing the prosthesis in segments, so as not to have a rigid entity encased in flexing bone that may induce stress in the bone, potentially leading to loss of implant integration and failure. Segmenting also ensures an appropriate fit of the prosthesis with respect to casting and porcelain firing distortion. Lip support by means of a flange in the prosthesis may be necessary when there has been a large amount of bone loss from edentulous resorption. Cleaning and routine maintenance of the prostheses every 3,6 months is essential. [source] | ||||||||||