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Upper Molars (upper + molar)
Selected AbstractsExpression of c-Fos protein in the trigeminal nuclear complex resulting from quantified force application to the rat molarJOURNAL OF ORAL REHABILITATION, Issue 11 2003M. Watanabe summary, This study was conducted to investigate the expression and distribution of c-Fos-like immunoreactive neurones (Fos-neurones), in the rat trigeminal sensory nuclear complex, produced by mechanical forces with various magnitudes and durations applied to the left upper first molar. The magnitudes of forces applied to the tooth were 25, 50 and 100 g and the duration was 2 h. A quantified force of 100 g was also applied to the upper molar for varying durations [short-time (1,2 min)], 2, 4, 8 and 12 h. Fos-neurones distributed in the bilateral superficial laminae of the subnucleus caudalis, and the ipsilateral dorsomedial part of subnucleus oralis (Sp5Odm). The number of Fos-neurones increased in the subnucleus caudalis (Sp5C) according to the force magnitude. In the Sp5C, the number of Fos-neurones exhibited maximum level, 2 or 4 h after the application. In the Sp5Odm, however, the number of Fos-neurones reached the maximum level at 8 h. These data suggest that the change in the number of nociceptive neurones in Sp5C reflect changes in encoding the magnitude of force to tooth, and that the nature of pain response to orthodontic forces might have some relation to the delayed expression of c-Fos protein in the Sp5Odm. [source] Investigation of the factors related to the formation of the buccal mucosa ridgingJOURNAL OF ORAL REHABILITATION, Issue 6 2003I. Takagi summary, The aim of this study was to clarify the factors related to the formation of the buccal mucosa ridging, which has been mentioned to be a clinical sign of clenching. Twenty-one individuals were investigated and divided into three groups: (i) those without buccal mucosa ridging, (ii) the buccal mucosa ridging located in all the posterior teeth region, and (iii) the buccal mucosa ridging corresponding only to the molar teeth region. A pressure sensor was used and placed at two points: first upper premolar and second upper molar. The recording tasks were: (i) silent reading at rest, (ii) light voluntary clenching, (iii) maximum voluntary clenching, (iv) holding the cheeks tightly against the teeth while light voluntary clenching, (v) holding the cheeks tightly against the teeth without tooth contact, (vi) pulling angle of mouth laterally while light voluntary clenching, (vii) pulling angle of mouth laterally without tooth contact and (viii) swallowing. No significant differences were found between groups in all the recording tasks except for the swallowing, at which significant difference (P < 0·05) was found between the groups of individuals having buccal mucosa ridging and without it. Based on these results it became clear that the buccal mucosa pressure exerted on the buccal aspect of teeth during swallowing plays an important role in the formation of buccal mucosa ridging. [source] A geometric morphometric analysis of the shape of the first upper molar in mice of the genus Mus (Muridae, Rodentia)JOURNAL OF ZOOLOGY, Issue 4 2006M. Macholán Abstract Phenotypic variation in the shape of the first upper molar among 595 mice, representing nine extant and three extinct taxa of the genus Mus, was studied with thin-plate spline analysis. The reliability of classification of individual specimens into known groups based on their molars varied from 75 to 100%, depending on group and method used. Including 13 sliding semilandmarks to the analysis improved the detection of different kinds of size and shape variation as well as visualization of shape differences between studied groups. Correlation between phylogenetic and morphometric distances suggested about 80% contribution of phylogenetic inertia to the molar shape variation; moreover, the importance of localized versus global shape changes was similar in the detection of phylogenetic signals. Finally, shape changes along individual evolutionary lineages were revealed, suggesting a few cases of reversals, convergence and/or retention of ancestral shape. The evolution of mouse molars has thus been driven by random effects of drift together with stabilizing selection and convergence. [source] Earliest Miocene hominoid from Southeast AsiaAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2004Yutaka Kunimatsu Abstract A new hominoid fossil site, Chiang Muan in northern Thailand, yielded the first finding of a large-bodied Miocene hominoid in Southeast Asia. This specimen (CMu6-1,00) was preliminarily reported by Kunimatsu et al. ([2000a] Primate Res. 16:299). Later, Chaimanee et al. ([ 2003] Nature 422:61,65) reported additional hominoid teeth from the same site, but all of them were collected from younger deposits (the Upper Lignite Member, in Nagaoka and Suganuma [ 2002] Primate Res 18:159,164). The specimen described here (CMu6-1,00) was recovered from the Lower Lignite Member (Nagaoka and Suganuma [ 2002] Primate Res 18:159,164), which is probably several hundred thousand years older than the Upper Lignite Member (Suganuma et al. [ 2002] Primate Res. 18:165,173). This article provides a detailed description of this hominoid specimen and paleontological/geological data of the fossil site at Chiang Muan. The hominoid specimen (CMu6-1,00) is an isolated upper molar (right M1 or M2), similar in size to modern orangutans (Pongo pygmaeus). This upper molar has low and voluminous cusps, relatively thick enamel, and relatively low relief of the dentine/enamel junction, with only a faint remnant of the lingual cingulum. The age of Chiang Muan is estimated to be the latest Middle Miocene (ca. 11,12 Ma), based on the mammalian fossils (Nakaya et al. [ 2002] Primate Res. 18:131,141) and paleomagnetic study (Suganuma et al. [ 2002] Primate Res. 18:165,173). This suggests that the Chiang Muan Hominoid in the present study is an earlier member of Eastern Eurasian Miocene hominoids. Am J Phys Anthropol, 2003. © 2003 Wiley-Liss, Inc. [source] Evolution of M1 crown size and cusp proportions in the genus HomoJOURNAL OF ANATOMY, Issue 5 2009Rolf Quam Abstract Previous research into tooth crown dimensions and cusp proportions has proved to be a useful way to identify taxonomic differences in Pliocene and Pleistocene fossil hominins. The present study has identified changes in both M1 crown size and cusp proportions within the genus Homo, with M1 overall crown size reduction apparently occurring in two main stages. The first stage (a reduction of ca. 17%) is associated with the emergence of Homo ergaster and Homo erectus sensu stricto. The second stage (a reduction of ca. 10%) occurs in Homo sapiens, but the reduced modern human M1 tooth crown size was only attained in Upper Paleolithic times. The absolute sizes of the individual cusps are highly positively correlated with overall crown size and dental reduction produces a reduction in the absolute size of each of the cusps. Most of the individual cusps scale isometrically with crown size, but the paracone shows a negative allometric relationship, indicating that the reduction in paracone size is less than in the other M1 cusps. Thus, the phylogenetically oldest cusp in the upper molars also seems to be the most stable cusp (at least in the M1). The most striking change in M1 cusp proportions is a change in the relative size of the areas of the paracone and metacone. The combination of a small relative paracone and a large relative metacone generally characterizes specimens attributed to early Homo, and the presence of this character state in Australopithecus and Paranthropus suggests it may represent the primitive condition for the later part of the hominin clade. In contrast, nearly all later Homo taxa, with the exception of Homo antecessor, show the opposite condition (i.e. a relatively large paracone and a relatively small metacone). This change in the relationship between the relative sizes of the paracone and metacone is related to an isometric reduction of the absolute size of the metacone. This metacone reduction occurs in the context of relative stability in the paracone as crown size decreases. Among later Homo taxa, both Homo heidelbergensis and Homo neanderthalensis show a further reduction of the metacone and an enlargement of the hypocone. Fossil and contemporary H. sapiens samples show a trend toward increasing the relative size of the protocone and decreasing the relative size of the hypocone. In Europe, modern human M1 cusp proportions are essentially reached during the Upper Paleolithic. Although some variation was documented among the fossil taxa, we suggest that the relative size of the M1 paracone and metacone areas may be useful for differentiating the earliest members of our genus from subsequent Homo species. [source] Mandibles and molars of the wood mouse, Apodemus sylvaticus (L.): integrated latitudinal pattern and mosaic insular evolutionJOURNAL OF BIOGEOGRAPHY, Issue 2 2007Sabrina Renaud Abstract Aim, The distinct nature of island populations has traditionally been attributed either to adaptation to particular insular conditions or to random genetic effects. In order to assess the relative importance of these two disparate processes, insular effects were addressed in the European wood mouse, Apodemus sylvaticus (Linnaeus, 1758). Location, Wood mice from 33 localities on both mainland and various Atlantic and western Mediterranean islands were considered. This sampling covers only part of the latitudinal range of A. sylvaticus but included the two main genetic clades identified by previous studies. Islands encompass a range of geographical conditions (e.g. small islands fringing the continent through large and isolated ones). Methods, The insular syndrome primarily invokes variations in body size, but ecological factors such as release from competition, niche widening and food availability should also influence other characters related to diet. In the present study, the morphology of the wood mice was quantified based on two characters involved in feeding: the size and shape of the mandibles and first upper molars. The size of the mandible is also a proxy for the body size of the animal. Patterns of morphological differentiation of both features were estimated using two-dimensional outline analysis based on Fourier methods. Results, Significant differences between mainland and island populations were observed in most cases for both the mandibles and molars. However, molars and mandibles displayed divergent patterns. Mandible shape diverged mostly on islands of intermediate remoteness and competition levels, whereas molars exhibited the greatest shape differentiation on small islands, such as Port-Cros and Porquerolles. A mosaic pattern was also displayed for size. Body and mandible size increased on Ibiza, but molar size remained similar to mainland populations. Mosaic patterns were, however, not apparent in the mainland populations. Congruent latitudinal variations were evident for the size and shape of both mandibles and molars. Main conclusions, Mosaic evolution appears to characterize insular divergence. The molar seems to be more prone to change with reduced population size on small islands, whereas the mandible could be more sensitive to peculiar environmental conditions on large and remote islands. [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] Cephalometric evaluation of the effects of pendulum appliance on various vertical growth patterns and of the changes during short-term stabilizationORTHODONTICS & CRANIOFACIAL RESEARCH, Issue 1 2001Ms Toro The aim of this study was to evaluate the effects of the pendulum appliance in dental Class II patients with varying vertical growth patterns and to evaluate the changes during the short-term stabilization period of 3 months. The sample (n=30) was divided into two groups based on their FMA°. The high-angle group consisted of 14 patients (10 girls and 4 boys) and had a mean age of 157.7±8.0 months. The low-angle group consisted of 16 patients (8 girls and 8 boys) and had a mean age of 155.5±18.6 months. Pretreatment, posttreatment and poststabilization cephalometric radiographs were obtained to measure the changes. Mann,Whitney U and Wilcoxon tests were used for statistical evaluation. The amount of upper molar distalization was 5.9 mm (p<0.001) in the high-angle group and 1 mm (p<0.001) in the low-angle group, showing no intergroup difference. The amount of anchorage loss at the second premolars was 4.8 mm (p<0.001) in the high-angle group and 6.6 mm (p<0.001) in the low-angle group. Upper incisors moved anteriorly for 2.1 mm (p<0.05) in the high-angle group and 4.1 mm (p<0.001) in the low-angle group. Intergroup difference was statistically significant (p<0.001). During the stabilization period, 1.5 mm of anchorage loss was measured at the upper molar region in the high-angle group and 1.7 mm of anchorage loss was measured at the upper molar region in the low-angle group. During the stabilization period, upper second premolars and incisors tended to move back to their original places. The results of this study showed that pendulum appliance could move the upper molars distally in a short period of time without depending on the patient compliance. Care should be taken to prevent anchorage loss and to stabilize the upper molars for, at least, 3 months. [source] NEW SPECIES OF PARAPHIOMYS (RODENTIA, THRYONOMYIDAE) FROM THE LOWER MIOCENE OF AS-SARRAR, SAUDI ARABIAPALAEONTOLOGY, Issue 2 2005RAQUEL LÓPEZ ANTOÑANZAS Abstract:, The family Thryonomyidae is represented in the Lower Miocene of Saudi Arabia by a single species, Paraphiomys knolli sp. nov. This new taxon differs from all other thryonomyids in being small, lower molars having a short metalophulid II and an isolated anterolabial cuspid, and upper molars being antero-posteriorly compressed and pentalophodont. A cladistic analysis involving all extinct and extant species of thryonomyids is provided. Paraphiomys knolli branches as the sister-species of Paraphiomys pigotti, type species of the genus. [source] Metastatic Renal Cell Carcinoma to the Head and Neck,THE LARYNGOSCOPE, Issue 9 2002Keith M. Pritchyk MD Abstract Objectives The objectives of the study were to present four cases of renal cell carcinoma (RCC) metastatic to the head and neck, to recognize the appearance on radiographic studies, to understand the importance of preoperative embolization, and to review the results of treatment. Study Design Retrospective review of patients diagnosed with metastatic RCC to the head and neck. Methods The records of four patients diagnosed with metastatic RCC at a tertiary medical center over a 5-year period from 1996 to 2001 were reviewed and analyzed for demographic and outcomes data. Results Metastatic RCC to the head and neck was seen in the following locations: nasal cavity, lower lip, hard palate, tongue, and maxillary sinus. Presenting signs were loose upper molars, dysphagia, nasal obstruction, lower lip lesion, recurrent epistaxis, and foul nasal drainage. Histological studies confirmed metastasis of RCC in all four patients. Treatment consisted of preoperative radiation therapy, embolization, and local excision with adjunct chemotherapy. Conclusions Metastatic RCC to the head and neck is rare but can have serious consequences if not recognized before biopsy. We present several treatment options with local excision as the primary mode of treatment. [source] Evolutionary history of the bank vole Myodes glareolus: a morphometric perspectiveBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 3 2010RONAN LEDEVIN The bank vole experienced a complex history during the Quaternary. Repeated isolation in glacial refugia led to the differentiation of several lineages in less than 300 000 years. We investigated if such a recent differentiation led to a significant divergence of phenotypic characters between European lineages, which might provide insight into processes of intraspecific differentiation. The size and shape of the first and third upper molars, and first lower molar, of bank voles genetically attributed to different lineages were quantified using an outline analysis of their occlusal surface. The three teeth present similar trends of decreasing size towards high latitudes. This trend, the inverse of Bergmann's rule, is interpreted as the result of a balance between metabolic efficiency and food availability, favouring small body size in cold regions. Molar shape appeared to differ between lineages despite genetic evidence of suture zones. A mosaic pattern of evolution between the different teeth was evidenced. The analysis of such phenotypic features appears as a valuable complement to genetic analyses, providing a complementary insight into evolutionary processes, such as selective pressures, that have driven the differentiation of the lineages. It may further allow the integration of the paleontological dimension of the bank vole phylogeographic history. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 681,694. [source] | |||||||||||||