The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
Fen Wang - One of the best experts on this subject based on the ideXlab platform.
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fgfr2 in the dental epithelium is essential for development and maintenance of the maxillary cervical loop a stem cell niche in mouse Incisors
Developmental Dynamics, 2009Co-Authors: Yishing Lisa Cheng, Rena N Dsouza, Fen WangAbstract:Constant supplies of dental epithelial cells from stem cell niches in the cervical loop enable mouse Incisors to grow continuously through life. Fibroblast growth factor 10 (FGF10) has been shown to be essential for development of mouse Incisors and maintenance of Incisor cervical loops during prenatal development. Whether its cognate receptor, FGFR2IIIB, in the dental epithelium is required for postnatal tooth development remains unknown because Fgfr2IIIb ablation causes neonatal lethality. Here we report that tissue-specific ablation of Fgfr2 in the dental epithelium led to defective maxillary Incisors that lacked ameloblasts and the enamel, and had poorly developed odontoblasts. Although the cervical loop in Fgfr2 null maxillary Incisors was formed initially, it failed to continue to develop and gradually diminished soon after birth. The results suggest that the FGFR2 signaling axis plays a role in maintaining the stem cell niche required for Incisor development and lifelong growth. Developmental Dynamics 238:324–330, 2009. © 2008 Wiley-Liss, Inc.
Seiki Takatsuki - One of the best experts on this subject based on the ideXlab platform.
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female sika deer have evolved larger Incisors than males under relaxed selection against rapid tooth wear
Biological Journal of The Linnean Society, 2013Co-Authors: Mugino O Kubo, Masato Minami, Naoko Higuchi, Nobumasa Ohnishi, Ayumi Okada, Koichi Kaji, Takahiro Ohba, Eiji Hosoi, Toru Koizumi, Seiki TakatsukiAbstract:Incisor size is associated with feeding efficiency in herbivorous ungulates and may have been under selection in correspondence with food habits. In the meantime, males of polygynous, dimorphic species have smaller cheek teeth than females, possibly because their reproductive span is much shorter than that of females. Thus, males are not under selection for more durable teeth when there is no reproductive return. Therefore, Incisor size is expected to be under natural selection against wear and under the influence of sex-based differences in reproductive strategy. We first investigated Incisor wear in Japanese sika deer (Cervus nippon) and compared wear rates between the sexes and two ecologically contrasting populations on Kinkazan Island and Mt. Goyo. We then compared unworn Incisor size to test the hypotheses that female deer have relatively larger Incisors than males and a population with faster Incisor wear has larger Incisors. The Kinkazan deer showed significantly faster wear than those on Mt. Goyo, and Kinkazan males had faster wear than Kinkazan females. Unworn Incisor size was relatively larger for females than that for males and was larger for Kinkazan deer than that for Mt. Goyo deer. The sex-based difference in Incisor size was greater in Mt. Goyo deer than that in Kinkazan deer. These findings support the hypothesis that sex-based differences in reproductive span result in larger Incisor size for female sika deer and imply that strong natural selection against rapid tooth wear diminishes sex-based differences in Incisor size in Kinkazan deer. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2013, 110, 384–397.
Nair Galvao Maia - One of the best experts on this subject based on the ideXlab platform.
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unusual orthodontic correction of bilateral maxillary canine first premolar transposition
Angle Orthodontist, 2009Co-Authors: Francisco Ajalmar Maia, Nair Galvao MaiaAbstract:Abstract Tooth transposition is a subject that intrigues orthodontists because of the associated treatment planning. Approximately 0.3–0.4% of the population has this type of tooth disharmony, and in the literature, most authors are in disagreement about the treatment approach. In this article, a case is presented of bilaterally maxillary canine–first premolar transposition associated with bilaterally upper lateral Incisor agenesis treated in a very unusual way. The transposed teeth were orthodontically reversed to their normal sequence and the missing lateral Incisor spaces closed. We choose this approach because once the decision was made to close the upper lateral Incisor agenesis spaces, it was inadequate to position the upper first premolars in contact with the central Incisors.
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Unusual Orthodontic Correction of Bilateral Maxillary Canine–First Premolar Transposition
Angle Orthodontist, 2009Co-Authors: Francisco Ajalmar Maia, Nair Galvao MaiaAbstract:Abstract Tooth transposition is a subject that intrigues orthodontists because of the associated treatment planning. Approximately 0.3–0.4% of the population has this type of tooth disharmony, and in the literature, most authors are in disagreement about the treatment approach. In this article, a case is presented of bilaterally maxillary canine–first premolar transposition associated with bilaterally upper lateral Incisor agenesis treated in a very unusual way. The transposed teeth were orthodontically reversed to their normal sequence and the missing lateral Incisor spaces closed. We choose this approach because once the decision was made to close the upper lateral Incisor agenesis spaces, it was inadequate to position the upper first premolars in contact with the central Incisors.
Paivi Kettunen - One of the best experts on this subject based on the ideXlab platform.
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Sema3A chemorepellant regulates the timing and patterning of dental nerves during development of Incisor tooth germ
Cell and Tissue Research, 2014Co-Authors: Anjana Shrestha, Keijo Luukko, Masahiko Taniguchi, Paivi KettunenAbstract:Semaphorin 3A (Sema3A) axon repellant serves multiple developmental functions. Sema3A mRNAs are expressed in epithelial and mesenchymal components of the developing Incisor in a dynamic manner. Here, we investigate the functions of Sema3A during development of Incisors using Sema3A-deficient mice. We analyze histomorphogenesis and innervation of mandibular Incisors using immunohistochemistry as well as computed tomography and thick tissue confocal imaging. Whereas no apparent disturbances in histomorphogenesis or hard tissue formation of Sema3A ^ −/− Incisors were observed, nerve fibers were prematurely seen in the presumptive dental mesenchyme of the bud stage Sema3A ^ −/− tooth germ. Later, nerves were ectopically present in the Sema3A ^ −/− dental papilla mesenchyme during the cap and bell stages, whereas in the Sema3A ^ +/+ mice the first nerve fibers were seen in the pulp after the onset of dental hard tissue formation. However, no apparent topographic differences in innervation pattern or nerve fasciculation were seen inside the pulp between postnatal and adult Sema3A ^ +/+ or Sema3A ^ −/− Incisors. In contrast, an abnormally large number of nerves and arborizations were observed in the Sema3A ^ −/− developing dental follicle target field and periodontium and, unlike in the wild-type mice, nerve fibers were abundant in the labial periodontium. Of note, the observed defects appeared to be mostly corrected in the adult Incisors. The expressions of Ngf and Gdnf neurotrophins and their receptors were not altered in the Sema3A ^ −/− postnatal Incisor or trigeminal ganglion, respectively. Thus, Sema3A is an essential, locally produced chemorepellant, which by creating mesenchymal exclusion areas, regulates the timing and patterning of the dental nerves during the development of Incisor tooth germ.
D V Albuquerque - One of the best experts on this subject based on the ideXlab platform.
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a maxillary lateral Incisor with four root canals
International Endodontic Journal, 2012Co-Authors: J Kottoor, R Murugesan, D V AlbuquerqueAbstract:Kottoor J, Murugesan R, Albuquerque DV. A maxillary lateral Incisor with four root canals. International Endodontic Journal, 45, 393–397, 2012. Abstract Aim To describe the successful non-surgical endodontic management of a permanent maxillary lateral Incisor tooth with four root canals. Summary Aberrant morphology of root canals can occur in any tooth, including maxillary lateral Incisors. In the presented case, clinical examination and radiographs clearly depicted the presence of four root canals in a right maxillary lateral Incisor. The differential diagnosis included fusion, gemination, dens invaginatus or a combination of these. The report emphasises the need for attention during root canal treatment of maxillary lateral Incisors. Key learning points • Clinicians should be aware of the variable root canal anatomy in maxillary lateral Incisor teeth. • Careful examination of radiographs and the internal anatomy of teeth are essential prerequisites for successful root canal treatment. • Four root canals in maxillary lateral Incisors is a possibility.
