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PubMedDate not supplied

Cvek pulpotomy: report of a case with five-year follow-up.

Partial pulpotomy (Cvek pulpotomy) is the treatment of choice for injured permanent incisor teeth with exposed vital pulp tissue and immature apices. This treatment preserves pulpal function, thus allowing continued root development. The present report describes the case of a permanent incisor with incomplete root end closure that underwent a Cvek pulpotomy, with subsequent apical closure. Five years post pulp therapy, the tooth remained symptom free.

Calcium Hydroxide↗
PubMed1991

Establishment of acellular extrinsic fiber cementum on human teeth. A light- and electron-microscopic study.

The present study describes for the first time the development of early acellular extrinsic fiber cementum (AEFC) until its establishment on human teeth. Precisely selected premolars with roots developed to 50%-100% of their final length were prefixed in Karnovsky's fixative and most of them were decalcified in EDTA. Their roots were subdivided into about 10 blocks each, cut from the mesial and distal root surfaces. Following osmication, these blocks were embedded in Epon and sectioned for light- and transmission electron microscopy. Some blocks were cut non-demineralized. From semithin stained sections, the density of the collagenous fiber fringe protruding from the root surface was measured by using the Videoplan-system. After initiation of this fiber fringe and its attachment to the dentinal root surface followed by mineralization, the fringe gradually increased in length and subsequently became mineralized. Fringe elongation and the advancement of the mineralization front appeared to progress proportionally. Thus, in all stages of AEFC development, a short fiber fringe covered the mineralized AEFC. Its density remained constant, irrespective of AEFC thickness. The latter gradually increased and reached an early maximum of 15-20 microns in the cervical region. At this stage, the AEFC fringe appeared to fuse with the future dentogingival or other collagen fibers of the tooth supporting apparatus. Mineralization of the fringe commenced with isolated, spherical or globular centers, which later fused with the mineralization front and became incorporated in AEFC.

Adolescent↗
PubMed1995

Accuracy of two dental and one skeletal age estimation method in Swedish adolescents.

The paper concerns the accuracy of two dental methods of age estimation based on the radiographic appearance of the root of the lower third molar. The first dental method tested was traditional with a subjective assessment of the root development stage and the second was a new method with a metric measurement of formed root length. Since previous studies have shown a relatively low precision for dentally based age estimation methods during adolescence, an additional independent indicator of chronological age was employed, namely skeletal maturity according to the atlas and method of Greulich and Pyle (Radiographic Atlas of Skeletal Development of the Hand and Wrist Stanford University Press, CA, 1959). The material was Swedish adolescents aged 12-19 years. It was found that all methods gave an overestimation of chronological age, with the highest overestimation, more than 1 year, for the two dental methods. A stepwise multiple regression analysis indicated that skeletal age alone explains 48% of the variation in estimated chronological age. It may be concluded that the accuracy of age estimations based on the lower third molars is quite uncertain during adolescence. Up to 18 years, it is preferable to use skeletal age alone as a predictor. Only a small increase in the explanation coefficient of age variation (3-4%) could be seen if digitized or subjectively estimated root lengths were added as predictors to the skeletal estimation.

Adolescent↗
PubMed2001

Ultrastructure of early mineral deposition during hyaline layer formation in rat molars.

There is no consensus on whether the first mineralized layer, the hyaline layer, that is juxtaposed to root dentine is a variety of dentine or cementum or even a tissue of epithelial origin. Some suggest that there is no intermediate tissue between the acellular extrinsic fibre cementum (AEFC) and the root dentine. Here, to study hyaline layer formation and mineralization we examined by transmission electron microscopy the early stages of root development in upper molars from 10 to 13 day old Wistar rats. In addition to conventionally processed material, undemineralized and unstained sections were examined, which showed the deposition of fine mineral crystals in contact with the mineralized surface of root dentine. Early mineralization of the hyaline layer occurred in the region of the inner basement membrane, which persisted between the inner cellular layer of Hertwig's epithelial root sheath and the outer mineralized root dentine. When the root sheath began its fragment, collagen fibrils from the developing periodontal ligament began to insert into the mineralising hyaline layer, which was 0.5-0.8 micron wide. As the fragmentation of the root sheath HERS increased, more collagen fibrils appeared intermingled with the mineralising hyaline layer. In more advanced stages, when the hyaline layer had become fully mineralized and the formation of the AEFC began, the hyaline layer could no longer be identified. Thus, the hyaline layer is clearly discernible at early stages of periodontal development. Subsequently, it is masked by intermingling of cementum and dentine and therefore it is not possible to detect it in the formed roots of rat molars.

Animals↗
PubMed1991

Acute pulpal-alveolar cellulitis syndrome V. Apical closure of immature teeth by infection control: case report and a possible microbial-immunologic etiology. Part 1.

Das with Matusow and Goodall previously noted the rapid clinical apexogenesis of nonvital immature permanent teeth that are involved with an acute endodontic cellulitis. This apexogenesis was achieved by control of infection and by nonspecific intracanal medication without the use of calcium hydroxide. The case report confirms the clinical observations. The experimental canine endodontic cellulitis in a Cebus primate was induced as an immunologic pulp infection with a facultative Streptococcus species. The noted epithelial proliferation and organization into lacelike strands and bilaminar loops, similar to Hertwig's epithelial root sheath in root development, appear to be immunologic and genetic in origin, with an acceleration of the root maturation process.

Animals↗
PubMed2003

WVD2 and WDL1 modulate helical organ growth and anisotropic cell expansion in Arabidopsis.

Wild-type Arabidopsis roots develop a wavy pattern of growth on tilted agar surfaces. For many Arabidopsis ecotypes, roots also grow askew on such surfaces, typically slanting to the right of the gravity vector. We identified a mutant, wvd2-1, that displays suppressed root waving and leftward root slanting under these conditions. These phenotypes arise from transcriptional activation of the novel WAVE-DAMPENED2 (WVD2) gene by the cauliflower mosaic virus 35S promoter in mutant plants. Seedlings overexpressing WVD2 exhibit constitutive right-handed helical growth in both roots and etiolated hypocotyls, whereas the petioles of WVD2-overexpressing rosette leaves exhibit left-handed twisting. Moreover, the anisotropic expansion of cells is impaired, resulting in the formation of shorter and stockier organs. In roots, the phenotype is accompanied by a change in the arrangement of cortical microtubules within peripheral cap cells and cells at the basal end of the elongation zone. WVD2 transcripts are detectable by reverse transcriptase-polymerase chain reaction in multiple organs of wild-type plants. Its predicted gene product contains a conserved region named "KLEEK," which is found only in plant proteins. The Arabidopsis genome possesses seven other genes predicted to encode KLEEK-containing products. Overexpression of one of these genes, WVD2-LIKE 1, which encodes a protein with regions of similarity to WVD2 extending beyond the KLEEK domain, results in phenotypes that are highly similar to wvd2-1. Silencing of WVD2 and its paralogs results in enhanced root skewing in the wild-type direction. Our observations suggest that at least two members of this gene family may modulate both rotational polarity and anisotropic cell expansion during organ growth.

Amino Acid Sequence↗
PubMed1988

Evaluation of the effects of F in acidified gelatin gel on root surface lesion development in vitro.

Oral exposed, natural root surfaces of extracted human teeth were subjected to artificial lesion formation in gels of dialyzed gelatin that contained 75 mM lactic and 25 mM acetic acid and 1, 3, 10, 32, 100, 320, 550, or 1,000 mg F/l at pH 4.3-4.4 and at 36 degrees C. Ca and PO4 demineralization per square millimeter exposed surface and lesion depth decreased with increased F concentrations, except for the levels above 320 mg/l. Quantitative microradiographic image analyses showed that the mean percent mineral content of the entire lesions relative to the adjacent sound tissue was constant at about 64% for the F levels less than 320 mg/l. F above 3 mg/l changed the mineral density profile of the lesions by eliminating subsurface lamination. This showed that sufficient F incorporated at the site of demineralization prevented lesion progression and that the best effect would be obtained for F levels between 100 and 320 mg/l. Higher levels of F may also prove to be beneficial by providing labile F from CaF2 formed in the root surface.

Acids↗
PubMed1988

Oral condition in children treated with bone marrow transplantation.

Oral health was studied in 49 children below 12 years of age treated with bone marrow transplantation (BMT). Dental treatment prior to BMT was required in 41% of the children. Ulceration of the mucous membranes in the mouth was observed in 37% of the patients during treatment. Those given methotrexate as prophylaxis against graft-versus-host disease (GVHD) exhibited oral ulcerations more frequently (p less than 0.05) than those given cyclosporin. One year after BMT all patients with a clinical chronic GVHD exhibited changes in the oral mucosa. During the first year after BMT 31% of the children developed carious lesions. Children treated with 10 Gy total body irradiation (TBI) had a significantly (p less than 0.05) reduced salivary secretion rate. Dental development was severely affected in children treated with TBI. These disturbances consisted of arrested root development, enamel hypoplasias and microdontia.

Bone Marrow Transplantation↗
PubMed1981

Endodontic treatment during root formation.

Various forms of endodontic treatment may be used in an attempt to maintain pulpal vitality during the period of root formation. In teeth with advanced caries but with no clinical evidence of pulpitis, indirect pulp capping with the retention of a small amount of softened dentine in the base of the cavity is preferable to further excavation and direct capping of a resulting exposure. Direct capping of pulpal exposures in traumatized incisors is confined to teeth in which the tissue loss is limited and the exposure is small and recent. Where there is more serious contamination of the pulp, whether by trauma or by caries, pulpotomy is indicated. In each of these three forms of treatment, calcium hydroxide is the dressing of choice. In incompletely formed teeth with necrotic pulps, the anatomy of the root canal poses problems which may not be entirely evident radiographically because of differential root development in the buccolingual and mesiodistal planes, whilst surgical treatment may result in excessive root shortening, besides being unacceptable to many patients. Treatment of these teeth is directed towards stimulating calcific closure of the apical foramen, preparatory to the insertion of a conventional root filling. Important factors in this form of treatment are the removal of necrotic tissue from the root canal, the preservation of vital tissue in the apical part of the root, and the use of a suitable agent as a root canal dressing. Calcium hydroxide is the agent of choice for this purpose.

Calcium Hydroxide↗
PubMed1992

Initial formation of cellular intrinsic fiber cementum in developing human teeth. A light- and electron-microscopic study.

The present study describes the formative process of the initiation of cellular intrinsic fiber cementum (CIFC) in still growing human teeth. From 29 premolars and molars with incomplete roots developed to 60-90% of their final length, 8 premolars (with roots formed to three quarters of their final length) were selected for electron-microscopic investigation. All teeth were clinically intact and prefixed in Karnovsky's fixative immediately after extraction. Most of them were decalcified in ethylene diaminetetraacetic acid (EDTA), and the apical part of the roots was divided axially into mesial and distal portions that were subdivided in about 5 slices each. Following osmication and embedding in Epon, these blocks were cut for light- and electron-microscopic examination. In addition, 5 teeth with incomplete roots were freed from organic material and processed for scanning electron microscopy. It was found that CIFC-initiation commenced very close to the advancing root edge and resulted in a rapid cementum thickening. Thereafter, appositional growth continued on the already established cementum surface. Large, basophilic and rough endoplasmic reticulum-rich cementoblasts, some of which became cementocytes, were responsible for both fast and slow CIFC-formation. The CIFC-matrix was free of Sharpey's fibers and composed of more or less organized intrinsic collagen fibrils, in part fibril bundles, that ran roughly parallel to the root surface. Initially, the cementum fibrils intermingled with those of the dentinal collagen fibrils, which were not yet mineralized. This boundary subsequently underwent calcification. The development of collagen fibril bundles and their extracellular arrangement were associated with cytoplasmic processes probably involved in fibril formation and fibril assembly. Many cementoblasts contained intracytoplasmic, membrane-bounded collagen fibrils, which probably were related to fibril formation rather than degradation.

Adolescent↗
PubMed1996

Temperature-sensitive mutations that arrest Arabidopsis shoot development.

To identify genes involved in meristem function we have designed a screen for temperature-sensitive mutations that cause a conditional arrest of early shoot development in Arabidopsis. We describe the characterization of three mutations, arrested development (add) 1, 2 and 3. At the restrictive temperature the add1 and add2 mutations disrupt apical meristem function as assayed by leaf initiation. Furthermore, add1 and add2 plants exhibit defects in leaf morphogenesis following upshift from permissive to restrictive temperature. This result suggests that proximity to a functional meristem is required for the completion of normal leaf morphogenesis. The add3 mutation does not have a dramatic effect on the production of leaves by the apical meristem; however, add3 prevents the expansion of leaf blades at high temperature. Thus, in this mutant the temperature-dependent arrest of epicotyl development is due to a failure of normal leaf development rather than new leaf initiation. While all add mutants have a reduced rate of root growth in comparison to wild-type plants, the mutants do not display a temperature-dependent arrest of root development. All add mutants display some developmental defects at low temperature, suggesting that these mutations affect genes involved in inherently temperature-sensitive developmental processes.

Arabidopsis↗
PubMed2003

The Medicago species A2-type cyclin is auxin regulated and involved in meristem formation but dispensable for endoreduplication-associated developmental programs.

Phytohormones as well as temporal and spatial regulation of the cell cycle play a key role in plant development. Here, we investigated the function and regulation of an alfalfa (Medicago sativa) A2-type cyclin in three distinct root developmental programs: in primary and secondary root development, nodule development, and nematode-elicited gall formation. Using transgenic plants carrying the Medsa;cycA2;2 promoter-beta-glucuronidase gene fusion, in combination with other techniques, cycA2;2 expression was localized in meristems and proliferating cells in the lateral root and nodule primordia. Rapid induction of cycA2;2 by Nod factors demonstrated that this gene is implicated in cell cycle activation of differentiated cells developing to nodule primordia. Surprisingly, cycA2;2 was repressed in the endoreduplicating, division-arrested cells both during nodule development and formation of giant cells in nematode-induced galls, indicating that CycA2;2 was dispensable for S-phase in endoreduplication cycles. Overexpression of cycA2;2 in transgenic plants corresponded to wild type protein levels and had no apparent phenotype. In contrast, antisense expression of cycA2;2 halted regeneration of somatic embryos, suggesting a role for CycA2;2 in the formation or activity of apical meristems. Expression of cycA2;2 was up-regulated by auxins, as expected from the presence of auxin response elements in the promoter. Moreover, auxin also affected the spatial expression pattern of this cyclin by shifting the cycA2;2 expression from the phloem to the xylem poles.

Animals↗
PubMed2001

Endogenous hormone levels in explants and in embryogenic and non-embryogenic cultures of carrot.

Carrot (Daucus carota L. F1 hybrid Starca) excised hypocotyls were cultured on Murashige and Skoog medium with and without 2,4-dichlorophenoxy acetic acid (2,4-D) to determine the effect of this plant growth regulator on their further development and their endogenous hormone levels. Culture in the absence of 2,4-D stimulated root development at one end of the hypocotyl segments and increased the endogenous levels of free indole-3-acetic acid (IAA), zeatin/zeatin riboside and N6(Delta2-isopentenyl) adenine/N6(Delta2-isopentenyl) adenosine, as determined by radio-immunoassay. On the other hand, the presence of 2,4-D in the culture medium promoted callus induction and proliferation, together with abscisic acid (ABA) accumulation, in the hypocotyl segments during the first weeks of culture. When the callus segments generated in the hypocotyl sections cultured in the presence of 2,4-D were cultivated further, the development of two callus types was observed, one composed of preglobular and globular embryos and the other translucent, watery and lacking any sign of organisation. The embryos of the first type germinated when callus segments were transferred to regeneration conditions, while no change was observed when the second type was induced to regenerate. Higher levels of free IAA and ABA were obtained in the embryogenic calli when compared to the non-embryogenic, while no differences were observed among callus types in the other hormones evaluated. The possible role of the different plant hormones during induction of somatic embryogenesis is discussed.

Journal Article↗
PubMed1999

Adventitious root growth and cell-cycle induction in deepwater rice

Deepwater rice (Oryza sativa) is adapted to survive conditions of severe flooding over extended periods of time. During such periods adventitious roots develop to provide water, nutrients, and anchorage. In the present study the growth of adventitious roots was induced by treatment with ethylene but not auxin, cytokinin, or gibberellin. Root elongation was enhanced between 8 and 10 h after submergence. The population of cells in the S phase and expression of the S-phase-specific histone H3 gene increased within 4 to 6 h. Within 6 to 8 h the G2-phase population increased. Cell-cycle activation was accompanied by sequential induction of a cdc2-activating kinase homolog, R2, of two cdc2 genes, cdc2Os-1 and cdc2Os-2, and of three cyclin genes, cycA1;3, cycB2;1, and cycB2;2, but only induction of the R2 gene expression preceded the induction of the S phase, possibly contributing to cell-cycle regulation in the G1 phase. Both cdc2 genes were expressed at slightly higher levels during DNA replication. Transcripts of the A-type cyclin accumulated during the S and G2 phases, and transcripts of the B-type cyclins accumulated during the G2 phase. Cyclin expression was induced at all nodes with a similar time course, suggesting that ethylene acts systemically and that root primordia respond to ethylene at an early developmental stage.

Journal Article↗
PubMed1991

Regulation of phytochrome message abundance in root caps of maize.

In many cultivars of maize (Zea mays L.) red light affects root development via the photomorphogenetic pigment phytochrome. The site of perception for the light is the root cap. In the maize cultivar Merit, we investigated phytochrome-mediated events in the cap. We established that the message encoded by the phyA1 gene was most abundant in dark-grown tissue and was asymmetrically distributed in the root cap, with greatest expression in the cells which make up the central columella core of the cap. Phytochrome message was negatively autoregulated in a specific region within the root cap. This autoregulation was sensitive to very-low-fluence red light, and thus was characterized as a phytochrome-mediated, very-low-fluence event. The kinetics of message reaccumulation in the dark were also examined and compared to the kinetics of the light requirement for root gravitropism in this cultivar. Similarly, the degree of autoregulation present in two other maize cultivars with different light requirements for gravitropic sensitivity was investigated. It appears that the Merit cultivar expresses a condition of hypersensitivity to phytochrome-mediated light regulation in root tissues. We conclude that phytochrome regulates many activities within the cap, but the degree to which these activities share common phytochrome-mediated steps is not known.

Darkness↗
PubMed2000

Treatment of teeth with open apices using mineral trioxide aggregate.

Injuries to the dentition may ultimately result in the interruption of root development. If the pulp remains vital following trauma, this state should be maintained and root-end closure should be induced by apexogenesis. When the pulp is necrotic, the placement of an apical barrier can be utilized as an alternative to establish an environment that facilitates the closure of the apical opening. This article demonstrates the use of mineral trioxide aggregate as an apical barrier material for root-end closure in the permanent teeth of three patients.

Aluminum Compounds↗
PubMed2001

[Radiographic study of the development of the permanent teeth].

OBJECTIVE: To study the development of permanent teeth by radiographic methods. METHODS: The permanent teeth development of children ranging from 4-17 years was evaluated from 1709 panoramic radiographs by the Nolla's method. Each tooth was graded from 0 to 10 stage. The average developmental stage for girls and boys were calculated. RESULTS: The average developmental stage and development curves for girls and boys were obtained respectively. For the completion of crown and root development, girls are more advanced than boys by an average of 0.3 and 0.6 years. CONCLUSIONS: Girls are ahead of boys for the development of the permanent teeth. The norms of the maturation of permanent teeth can be used to evaluated the development of the individual teeth.

Adolescent↗
PubMed2000

Characterizing the interaction between fire ants (Hymenoptera: Formicidae) and developing soybean plants.

This research characterizes the interaction between the fire ants Solenopsis invicta Buren and developing soybean plants. Phagostimulant studies showed that fire ant foraging on soybean seeds increased once the seeds imbibed water. During seedling development over a 5-d germination period, fire ant foraging shifted from the stem/cotyledons to the roots, despite continual increases in fresh weights for each region, and the fact that stem/cotyledon tissue contained the majority of food reserves. Carbohydrate analysis showed that although 2-d-old seedlings had higher concentrations of phagostimulant carbohydrates, especially sucrose, than tissues of mature plants, all tissues analyzed had enough of these sugars to induce a phagostimulant response. Fire ant association with seeds/seedlings germinated in soil resulted in reduced seedling vigor, as determined by a doubling of seedling emergence time, a threefold increase in malformed seedlings, and visible damage to cotyledons. Seeds germinated and grown to mature plants in association with fire ants, allocated 43% more assimilate into pods, but produced 28% less root dry matter, 11% less total dry matter, and there was an 81% reduction in the number of root nodules compared with control plants. We propose that reduced root development and inhibitions of nodule formation would be major yield limiting factors under field conditions. This work demonstrates that fire ant damage to soybeans is not limited to seedling establishment and that more research should be directed at the subterranean activities of the fire ant.

Animals↗