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At least 127 records · Page 7Linked to original sources
PubMed1991

[The tooth transplant in orthodontic treatment planning].

The analysis of all examined transplant cases combined treated with orthodontics shows a success rate of 76%. It must be underlined that the germ development at the time of the transplantation is of utmost importance. The best possible time proved to be at a root development of 2/3 to 3/4. Exact indication position, a careful atraumatic operation method and a short time of operation are also important factors of a successful transplantation. If all these preconditions are met, this method can be recommended.

Adolescent↗
PubMed1978

The microscopic pattern of tetracycline fluorescence in the cementum of human teeth.

Ultraviolet microscopy of longitudinal non-decalcified sections revealed fluorescence characteristic of in vivo tetracycline deposition in the cementum of 55 out of 378 human permanent teeth. Patterns of fluorescence could be related to various stages in root development and to pathological events, as well as to the approximate duration of drug intake. Cementum lines formed during apposition of primary root dentin were associated with dentin bands and met the latter at the cemento-dentinal junction: other lines corresponded to incremental cementum apposition after completion of the root. Label was also visualized in localized areas of cementum hyperplasia and in repaired resorption lacunae. Discontinuities in broad fluorescent lines at or near the cementum surface were related to lack of connective tissue attachment when drug exposure occurred, or with subsequent root caries. Observations suggest that typical short, single periods of antibiotic therapy are recorded in the cementum, although marginally or close to the limit of resolution in some cases. Longer, chronic administration or multiple short regimens closely spaced in time are clearly registered. Study of these patterns may be useful in clinical periodontal research.

Dental Cementum↗
PubMedDate not supplied

Premature extractions of primary molars and the crown/root ratio of their permanent successors.

The effect of premature extractions of primary molars on further development of their successors was studied. A group of forty-six children with fifty-three unilaterally extracted mandibular primary molars was examined when the successors completed their root development. Radiographs of the successors to the extracted molars and their antimeres, which served as internal controls, were taken using the long-cone technique. Crown and root length and area in cross-section, were measured from tracings of the studied teeth and crown/root ratios were calculated. Significantly (p less than 0.05) larger area ratio in the extraction group was found suggesting a smaller root area. In addition, root foreshortening for the first premolars and diminished root area for the second premolars, both successors to teeth extracted after the age of eight years, were found. Although statistically significant, all of the differences were of no clinical importance.

Bicuspid↗
PubMed2025

Integrative omics of the genetic basis for wheat WUE and drought resilience reveal the function of TaMYB7-A1.

Improving wheat drought resilience and water use efficiency (WUE) is critical for sustaining productivity under increasing water scarcity. Here, we integrate genome-wide association study (GWAS), expression quantitative trait locus (eQTL) mapping, population-transcriptome analysis, and summary-data-based mendelian randomization (SMR), followed by functional validation using indexed EMS mutants and transgenic lines, to systematically identify key WUE regulators. GWAS across water conditions in 228 accessions identifies 73 quantitative trait loci (QTLs) for WUE-traits. Transcriptome profiling of 110 diverse accessions reveals 28 drought-responsive modules. eQTL mapping uncovers 146,966 regulatory variants, including condition-specific hotspots associated with key drought-related pathways. Integrative analysis underscores 85 high-confidence candidate genes, notably TaMYB7-A1. Overexpression of TaMYB7-A1 enhances photosynthesis, WUE, root development, and grain yield under drought condition by activating TaPIP2;2-B1 (water transport), TaRD20-D1 (stomatal regulation), and TaABCB4-B1 (root growth), reflecting reduced water loss and improved physiological resilience. Our study presents a comprehensive regulatory map and robust targets for wheat drought adaptation and resilient cultivar breeding.

Triticum↗
PubMed1989

The prevalence of taurodontism in Down's syndrome.

Taurodontism, a condition in which the pulp chambers of teeth are elongated, was observed in extracted lower molars of 12 out of 33 (36.4%) individuals with Down's syndrome (DS). It is suggested that this high prevalence is associated with a delayed ingrowth and fusion of the epithelial flaps of the developing root sheath and that taurodontism represents one of several characteristic morphological dental features in DS that result from decreased mitotic activity of cells in developing tooth germs.

Adolescent↗
PubMed2025

Integrative spatial transcriptomic analysis pinpoints the role of the ferroxidase, TaMCO3, in wheat root tip iron mobilization.

Roots play a critical role in the sensing and absorption of essential minerals from the rhizosphere. Iron (Fe) deficiency, for example, triggers a well-known series of physiological and molecular responses within roots that facilitate uptake, which differs between monocots and dicots. In monocots, little is known about the molecular responses that occur within specific root development zones in response to iron deprivation, and how these differences result in overall nutrient uptake. Here, we conducted a transcriptome analysis of wheat root tips under Fe deficiency (-Fe) and performed a comparative transcriptome analysis with the previous datasets generated from the whole root. Gene ontology analysis of differentially expressed genes highlighted the significance of oxidoreductase activity and metal/ion transport in the root tip, which are critical for Fe mobilization. Interestingly, wheat, an allohexaploid species consisting of three different genomes (A, B, and D) displayed varying gene expression levels arising from the three genomes that contributed to similar molecular functions. Detailed analysis of oxidoreductase function at the root tip revealed multiple multicopper oxidase (MCO) proteins, such as Fe-responsive TaMCO3, that likely contribute to the overall ferroxidase activity. Further characterization of TaMCO3 shows that it complements the yeast FET3 mutant and rescues the -Fe sensitivity phenotype of Arabidopsis atmco3 mutants by enhancing vascular Fe loading. Transgenic wheat lines overexpressing TaMCO3 exhibited increased root Fe accumulation and improved tolerance to -Fe by augmenting the expression of Fe-mobilizing genes. Our findings highlight the role of spatially resolved gene expression in -Fe responses, suggesting strategies to reprogram cells for improved nutrient stress tolerance.

Triticum↗
PubMed1990

Dentofacial development in long-term survivors of acute lymphoblastic leukemia. A comparison of three treatment modalities.

Ninety-seven children who were diagnosed with acute lymphoblastic leukemia before 10 years of age and treated with chemotherapy alone, chemotherapy plus 1800-cGy cranial irradiation (RT), or chemotherapy plus 2400-cGy RT were evaluated for effects of therapy on dentofacial development. All patients were seen at least 5 years postdiagnosis. Dental abnormalities were determined from panoramic radiographs, and craniofacial evaluations were made from lateral cephalometric radiographs. Ninety-one (94%) of all patients and 41 (100%) of patients younger than 5 years of age at diagnosis had abnormal dental development. The severity of these abnormalities was greater in children who received treatment before 5 years of age and in those who received RT. Observed dental abnormalities included tooth agenesis, arrested root development, microdontia, and enamel dysplasias. Craniofacial abnormalities occurred in 18 of 20 (90%) of those patients who received chemotherapy plus 2400-cGy RT before 5 years of age. Mean cephalometric values of this group showed significant deficient mandibular development. The results of this study suggest that the severity of dentofacial-developmental abnormalities secondary to antileukemia therapy are related to the age of the patient at the initiation of treatment and the use of cranial RT.

Adolescent↗
PubMed1990

Experimental study of pulpotomy with calcium hydroxide-iodoform paste in dogs' immature permanent teeth.

To investigate the healing process and continuous root development following pulpotomy with improved calcium hydroxide-iodoform paste, the authors performed an experimental study of pulpotomy in immature permanent teeth. Thirty five incompletely formed root canals in dogs were used, and radiographical and histopathological observations were made. The results lead to the conclusion that pulpotomy with improved calcium hydroxide-iodoform paste is a very effective treatment for immature permanent teeth.

Animals↗
PubMed1989

Accessory root formation on a lower medial incisor.

Accessory root formation on a lower medial incisor dating from the eighth century was observed. The accessory root consisted structurally of dentin (corresponding to the root of the tooth) covered with cement but had no radicular canal. It is therefore not a real supernumerary root. Postmortem deformation was excluded by examination of the alveolar bone. It must have been formed at the time of root development, through a lesion of Hertwig's sheath, as a result of a trauma.

Dentin↗
PubMed1991

Pulp capping of immature teeth with anatomic anomalies.

This case report describes the treatment of two immature teeth with anatomic anomalies which created plaque retentive areas and in one case occlusal disturbance. Periodontal and pulpal consequences were inevitable. Reshaping of the teeth was carried out which as expected led to exposure of the pulp in both instances. Pulp capping was then performed under aseptic conditions. The vitality of the teeth was maintained and continued root development was observed.

Adolescent↗
PubMed1989

Pulpal healing after luxation injuries and root fracture in the permanent dentition.

Pulpal healing patterns were studied in a clinical material of 637 luxated and 95 root-fractured permanent incisors followed routinely for up to 11 years. It was found that pulpal healing patterns could generally be divided into 3 groups according to the degree of injury sustained by the pulp: little, moderate or severe. Thus after luxation injuries, pulp survival could be without radiographic change (PS), with pulp canal obliteration (PCO) or nonhealing (pulp necrosis (PN]. After root fracture, similar healing patterns could be observed: healing by hard tissue union of fragments (HT), by connective tissue union of fragments (CT) or by nonunion due to interposition of granulation tissue between fragments (GT) resulting from PN of the coronal fragment. In both trauma situations, healing or nonhealing could be determined by type of luxation injury, stage of root development and type of fixation used (forceful application of orthodontic bands vs. passively applied acid-etch fixation). Pulpal healing complications (PN or GT) were based on clinical findings (coronal discoloration, loss of pulpal sensibility) and radiographic findings (resorption processes of the lamina dura at the root apex or at the level of the root fracture). However, in both injury groups the same changes could also be seen to be intermediate steps in the pulpal healing process. Based on findings from these studies, hypotheses for the mechanics of pulpal healing are proposed as well as guidelines for acute and later treatment of dental luxations, root fractures and the diagnosis of healing complications.

Dental Pulp↗
PubMed1989

Hertwig's epithelial root sheath differentiation and initial cementum and bone formation during long-term organ culture of mouse mandibular first molars using serumless, chemically-defined medium.

Studies were designed to test the hypothesis that Hertwig's epithelial root sheath (HERS) synthesizes and secretes enamel-related proteins that participate in the process of acellular cementum formation. Our experimental strategy was to examine sequential root development of the mouse mandibular first molar in vivo and in long-term organ culture in vitro using serumless, chemically-defined medium. Using anti-amelogenin, anti-enamelin and anti-peptide antibodies, enamel-related antigens were localized within intermediate cementum during HERS differentiation and root formation in vivo. Cap stage molars maintained for periods of up to 31 days in organ culture expressed morphogenesis and cytodifferentiation as identified by tooth crown and initial root, cementum and bone formation. Metabolically-labeled HERS products were analyzed by immunodetection using enamel-related antibodies and one- and two-dimensional SDS gel electrophoresis. A 72 kDa and 26 kDa polypeptide were identified in forming mouse cementum. Both of these root putative cementum proteins yield similar (identical) amino acid compositions; however, both proteins differed from the compositions of either mouse crown enamelin or amelogenin proteins. This approach provides a new and novel in vitro model towards understanding HERS differentiation and functions related to root and bone formation. The data support the hypothesis that HERS cells synthesize polypeptides related to but also different from canonical crown enamel proteins.

Animals↗
PubMedDate not supplied

[Nonsurgical endodontic treatment of an invaginated canine].

We present a case of a maxillary canine with a dens invaginatus treated successfully. The patient had pain, swelling and a sinus tract coming from the inmature apex of the canine. The canals were enlarged and cleaned and the main canal was filled with Calcium Hydroxide to allow the root development. Seven months later, the patient was asymptomatic and the tooth was obturated with guttapercha. One year later it was confirm the success in the treatment.

Adolescent↗
PubMed1976

Root fractures in permanent anterior teeth with incomplete root formation.

A follow-up study was made of seven teeth with incomplete root formation observed in a group of 66 permanent teeth with root fracture. Three fractures were overlooked on the initial radiographs, two other teeth were suspected of being fractured, and an accurate diagnosis was made in two cases only. All teeth exhibited markedly increased mobility at the initial examination, and slight dislocation of the coronal fragment was found in two teeth. Following reduction (two teeth) and fixation (all teeth), the observation period ranged from 1 1/2 to 19 years. Retained pulp vitality, repair in the fracture area and, most important, approximately normal root development with closure of the apical foramen were observed in all teeth. Even the occurrence of re-fracture in two semmingly repaired teeth did not jeopardize the long-term result.

Child↗
PubMed1988

1987 Kreshover lecture. Gene regulation in the development of oral tissues.

The regulatory processes associated with tooth formation are being investigated by the identification of when, where, and how cell adhesion molecules (CAMs), substrate adhesion molecules (SAMs), dentin phosphoprotein, enamel gene products, and intermediate cementum products are expressed during sequential developmental stages of morphogenesis, cytodifferentiation, dentin, enamel and cementum extracellular matrix (ECM) formation, and biomineralization. Instructive and permissive signaling is required for both morphogenesis and cytodifferentiation based upon in vitro organotypic culture studies in serumless, chemically-defined medium. Intrinsic developmental instructions, independent of exogenous growth factors, mediate tooth morphogenesis from the initiation of the dental lamina through crown and initial root development. Recent progress using recombinant DNA methods has advanced descriptions of several dental structural genes. The complete nucleic acid sequence for mouse amelogenin has been defined. This sequence is located on the mouse X chromosome and on the human X and Y chromosomes. This discussion summarizes recent results using experimental embryology, recombinant DNA technology, and immunocytology in the context of instructive epithelial-mesenchymal interactions associated with epithelial differentiation into ameloblasts, ectomesenchyme differentiation into odontoblasts, and dentin and enamel ECM biomineralization. The tooth organ provides opportunities at several levels of biological organization to investigate cellular, molecular, and developmental processes.

Animals↗
PubMed1987

Redistribution of Schwann cells in developing feline L7 ventral spinal roots.

The length and distribution of Schwann cells along fibres in the ventral root L7 of the developing cat have been studied electron microscopically in serial sections. The average Schwann cell length at the beginning of myelin formation - the 'initial internodal length' - was 118 micron (110 micron in alpha-axons and 124 micron in gamma-axons). The number of Schwann cells found in a fully developed root segment was already present at the beginning of the myelination. It showed no systematic age-dependent variation from the beginning of myelination to adulthood. The Schwann cells associated with alpha-axons increased their length 12.6 times during this period, while the root elongated 5.6 times. About 50% of the Schwann cells had to be eliminated in order to make the elongation of the remaining Schwann cells possible. Corresponding calculations from the mean length of Schwann cells associated with gamma-axons, showed that about 50% too few Schwann cells were associated with the gamma-axons during the period of initial myelination of the alpha-axons. At birth, when the myelination of gamma-axons had just begun, both the large surplus along alpha-axons and the deficit along gamma-axons had disappeared. We suggest that Schwann cells are eliminated from the alpha-axons and re-utilized along the gamma-axons. During this process of cellular redistribution, affected cells constitute so-called aberrant Schwann cells.

Age Factors↗
PubMed1990

A radiographic four-year follow-up study of asymptomatic mandibular third molars in young adults.

Fifty-five asymptomatic mandibular third molars (M3) in 34 dental students (mean age 20.6 years at the start of the study) were followed radiographically for 4 years. Based on clinical evaluation the 55 teeth included 20 almost erupted, 13 partly erupted and 22 non-erupted M3. The following were assessed on the radiographs: root development, level of eruption, sagittal angulation, resorption, pericoronitis/bony pockets/paradental cysts and widening of the periodontal space/dentigerous cysts. The state of 21 teeth (38 per cent) was radiographically changed at the end of the observation period. The most remarkable finding was that 15 teeth changed their sagittal angulation, all in a distal direction; five mesioangular to vertical, five vertical to distoangular, five mesioangular to distoangular. Radiographically, 13 M3 moved to a more advanced level of eruption. No real pathological osseous lesions and no root resorption were observed at initial or follow-up examinations. It is concluded that there are frequent essentially unpredictable changes in the position of M3 after the age of 19 years which may influence decisions on their removal or preservation.

Adult↗