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PubMedDate not supplied

Dens evaginatus: a review.

A review of the developmental dental anomaly, dans evaginatus, and a discussion of its clinical management is presented. Fracture or wear of the tubercle of dens evaginatus frequently results in pulp necrosis and early periapical infection, often prior to completion of root formation. Early recognition of this anomaly, followed by timely treatment can prevent the loss of pulp vitality in these teeth. Patients presenting with nonvital teeth and incomplete root development have been successfully treated by apexification followed by conventional endodontic therapy.

Bicuspid↗
PubMed2006

Ectopic expression of KNOTTED1-like homeobox protein induces expression of cytokinin biosynthesis genes in rice.

Some phytohormones such as gibberellins (GAs) and cytokinins (CKs) are potential targets of the KNOTTED1-like homeobox (KNOX) protein. To enhance our understanding of KNOX protein function in plant development, we identified rice (Oryza sativa) genes for adenosine phosphate isopentenyltransferase (IPT), which catalyzes the rate-limiting step of CK biosynthesis. Molecular and biochemical studies revealed that there are eight IPT genes, OsIPT1 to OsIPT8, in the rice genome, including a pseudogene, OsIPT6. Overexpression of OsIPTs in transgenic rice inhibited root development and promoted axillary bud growth, indicating that OsIPTs are functional in vivo. Phenotypes of OsIPT overexpressers resembled those of KNOX-overproducing transgenic rice, although OsIPT overexpressers did not form roots or ectopic meristems, both of which are observed in KNOX overproducers. Expression of two OsIPT genes, OsIPT2 and OsIPT3, was up-regulated in response to the induction of KNOX protein function with similar kinetics to those of down-regulation of GA 20-oxidase genes, target genes of KNOX proteins in dicots. However, expression of these two OsIPT genes was not regulated in a feedback manner. These results suggest that OsIPT2 and OsIPT3 have unique roles in the developmental process, which is controlled by KNOX proteins, rather than in the maintenance of bioactive CK levels in rice. On the basis of these findings, we concluded that KNOX protein simultaneously decreases GA biosynthesis and increases de novo CK biosynthesis through the induction of OsIPT2 and OsIPT3 expression, and the resulting high-CK and low-GA condition is required for formation and maintenance of the meristem.

Alkyl and Aryl Transferases↗
PubMed1996

Treatment of crown fractures with pulp exposure.

Thirty permanent incisors with vital pulps and complicated crown fractures were treated by a partial pulpotomy (Cvek technique). This consisted of amputation of 1 to 2 mm of the exposed pulp, placement of calcium hydroxide powder, and a temporary restoration. Clinical and radiographic assessment of the hard tissue barrier was done after 3 months and again after 1 to 8 years. The treatment was successful in all incisors. No differences were found in stage of root development, size of exposure, and length of time exposed. In conclusion, the partial pulpotomy technique is a successful and permanent treatment for crown fractures with pulp exposure regardless of the size of exposure, the maturity of the root, or the interval between accident and dental treatment.

Adolescent↗
PubMed2001

Isolation of the first putative peroxidase cDNA from a conifer and the local and systemic accumulation of related proteins upon pathogen infection.

Peroxidases are associated with the active defence reactions in higher plants in response to foreign organisms. They are involved in the oxidation of phenolic compounds in cell walls, polymerization of lignin and suberin, and in several other oxidation processes but the exact function of individual peroxidases is not known. We have isolated a cDNA encoding the putative defence-related and basic plant peroxidase SPI2 (spruce pathogen-induced 2), with an estimated molecular mass of 34 kDa, from roots of Norway spruce (Picea abies) seedlings. This is the first description of the isolation of a complete cDNA encoding a putative peroxidase from a gymnosperm. The transcript was present in the roots of healthy seedlings, and during infection with the pathogen Pythium dimorphum there was a rapid initial increase followed by a dramatic reduction of the transcript. The 34 kDa mature SPI2 protein was detected in both the developing root and shoot of healthy seedlings and increased amounts of SPI2 and increased accumulation of highly basic peroxidase isoforms was observed in roots after infection. In addition, two SPI2-related proteins with apparent molecular masses of 38 and 39 kDa, were also detected. Both these proteins accumulated in roots only after infection, and the 39 kDa protein was in addition detected in shoots of root-infected seedlings. Thus, both SPI2 and the SPI2-related proteins accumulate as a local response, in roots, and as a systemic response to infection the 39 kDa protein accumulates in the shoot.

Amino Acid Sequence↗
PubMed2001

The exodermis: a variable apoplastic barrier.

The exodermis (hypodermis with Casparian bands) of plant roots represents a barrier of variable resistance to the radial flow of both water and solutes and may contribute substantially to the overall resistance. The variability is a result largely of changes in structure and anatomy of developing roots. The extent and rate at which apoplastic exodermal barriers (Casparian bands and suberin lamellae) are laid down in radial transverse and tangential walls depends on the response to conditions in a given habitat such as drought, anoxia, salinity, heavy metal or nutrient stresses. As Casparian bands and suberin lamellae form in the exodermis, the permeability to water and solutes is differentially reduced. Apoplastic barriers do not function in an all-or-none fashion. Rather, they exhibit a selectivity pattern which is useful for the plant and provides an adaptive mechanism under given circumstances. This is demonstrated for the apoplastic passage of water which appears to have an unusually high mobility, ions, the apoplastic tracer PTS, and the stress hormone ABA. Results of permeation properties of apoplastic barriers are related to their chemical composition. Depending on the growth regime (e.g. stresses applied) barriers contain aliphatic and aromatic suberin and lignin in different amounts and proportion. It is concluded that, by regulating the extent of apoplastic barriers and their chemical composition, plants can effectively regulate the uptake or loss of water and solutes. Compared with the uptake by root membranes (symplastic and transcellular pathways), which is under metabolic control, this appears to be an additional or compensatory strategy of plants to acquire water and solutes.

Abscisic Acid↗
PubMed2002

Dental development after successful treatment of infantile osteopetrosis with bone marrow transplantation.

A 3-week-old boy was diagnosed with congenital osteopetrosis. He underwent a bone marrow transplant at 6 weeks of age. At 3 years of age the primary teeth had all erupted, but the canines and the first molars totally lacked root development. The teeth were smaller in size and had evidence of both enamel hypomineralization and hypoplasia. In the permanent dentition, multiple missing teeth were found. The incisors were conical and the mandibular laterals were extremely small. All permanent teeth had normal eruption. This case shows that dental development and eruption of teeth can be reconstituted in a child with congenital osteopetrosis. Bone marrow transplantation induces normalization of osteoclast function, which is a prerequisite for normal dental development and eruption of teeth.

Amelogenesis Imperfecta↗
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↗
PubMed1997

Use of calcium hydroxide for apical barrier formation and healing in non-vital immature permanent teeth: a review.

OBJECTIVE: To review the use of calcium hydroxide for induction of apical barrier formation and healing in immature permanent teeth. INTRODUCTION: Pulp necrosis is a frequent complication of dental trauma in immature permanent teeth. Endodontic treatment of these teeth is often complicated. The walls of the root canals are frequently divergent and the apices immature, making debridement and obturation difficult. The aim of treatment is induction of apical healing which may be defined as apical closure through formation of mineralised tissue and repair of the periapical tissues. Calcium hydroxide is the material of choice for apical barrier formation and healing. RESULTS: The use of calcium hydroxide for apical barrier formation is successful in 74-100% of cases irrespective of the proprietary brand used. The average length of time for apical barrier formation is approximately 5 to 20 months. Control of infection and adequate cleaning of the root canal are very important for apical healing. CONCLUSIONS: While the success rate of apical barrier formation using calcium hydroxide is high, long-term follow-up of these teeth is necessary. Problems such as failure to control infection, recurrence of infection and cervical root fracture may occur. The latter is more frequent in immature luxated teeth with the least root development.

Bacterial Infections↗
PubMed1984

CNS effects of mechanically produced spina bifida.

Neural-tube defects were produced by one of two mechanical perturbations in an amphibian model system: newly-formed neural tubes were slit dorsally, or an intrinsic mass (an eye primordium transplanted to the neural plate) was introduced to prevent dorsal closure. Electron microscopic analyses showed that the resulting CNS distortions invariably included paired spinal-cord tubes that developed ciliated central canals surrounded by cellular layers and rimmed laterally by axon-filled marginal zones. Specific axon tracts grew in appropriate locations through the regions of simple diastematomyelia. Even in the most histologically distorted regions, ventral roots developed, axons were myelinated, and neuromuscular synapses formed in adjacent muscles. On the other hand, an excess of cells populated the defects and in histologically distorted regions the axon tracts were clearly less well organized than in normal animals. Neural-crest cells and the notochord did not appear to be affected. In addition, distant neurons and axon tracts appeared normal. These mechanical lesions could produce spina bifida without hydrocephalus. It is concluded that mechanical lesions to the forming neural tube will produce mainly local effects with a strong tendency toward diastematomyelia.

Animals↗
PubMed2000

Hypaphorine from the ectomycorrhizal fungus Pisolithus tinctorius counteracts activities of indole-3-acetic acid and ethylene but not synthetic auxins in eucalypt seedlings.

Very little is known about the molecules regulating the interaction between plants and ectomycorrhizal fungi during root colonization. The role of fungal auxin in ectomycorrhiza has repeatedly been suggested and questioned, suggesting that, if fungal auxin controls some steps of colonized root development, its activity might be tightly controlled in time and in space by plant and/or fungal regulatory mechanisms. We demonstrate that fungal hypaphorine, the betaine of tryptophan, counteracts the activity of indole-3-acetic acid (IAA) on eucalypt tap root elongation but does not affect the activity of the IAA analogs 2,4-D ((2,4-dichlorophenoxy)acetic acid) or NAA (1-naphthaleneacetic acid). These data suggest that IAA and hypaphorine interact during the very early steps of the IAA perception or signal transduction pathway. Furthermore, while seedling treatment with 1-amincocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, results in formation of a hypocotyl apical hook, hypaphorine application as well as root colonization by Pisolithus tinctorius, a hypaphorine-accumulating ectomycorrhizal fungus, stimulated hook opening. Hypaphorine counteraction with ACC is likely a consequence of hypaphorine interaction with IAA. In most plant-microbe interactions studied, the interactions result in increased auxin synthesis or auxin accumulation in plant tissues. The P. tinctorius / eucalypt interaction is intriguing because in this interaction the microbe down-regulates the auxin activity in the host plant. Hypaphorine might be the first specific IAA antagonist identified.

Amino Acids↗
PubMed2001

Antisense expression of a cell wall-associated protein kinase, WAK4, inhibits cell elongation and alters morphology.

The Arabidopsis cell wall-associated receptor-like kinase (WAK) gene family contains five highly related members whose products are suited for exchanging signals between the intracellular and extracellular compartments. WAK members are expressed in specific organs and regulated differentially by various biotic and abiotic factors. To gain further insight into how WAKs function during development, we used a glucocorticoid-inducible system to express ectopically the WAK4 antisense gene. The induced expression of the WAK4 antisense gene resulted in a significant decrease of WAK proteins. Ninety-six hours after the induction of WAK4 antisense expression, WAK proteins became undetectable. Cell elongation was impaired, and lateral root development was blocked. The level of WAK protein could be controlled by the concentration of the applied inducer, dexamethasone, and was correlated with the severity of the cell elongation inhibition phenotype. These results suggest that the WAKs serve a vital role in cell elongation and are required for plant development.

Antisense Elements (Genetics)↗
PubMed1982

Follow-up study of permanent incisors with complicated crown fractures after acute trauma.

Complicated fractures occur in 3.5% of acute traumatized incisors. A pulp exposure results in almost all cases in endodontic treatment. The present investigation evaluated the prognosis for the different types of endodontic treatments following complicated crown fractures. Only incisors with an observation period of more than 23 months are included; the material comprises 301 incisors. Pulp capping was successful in 90.5% of the cases. There was a clear tendency for a positive correlation between the stage of the root development and the success rate of the endodontic treatment. In cases with pulpotomy ZnO/eugenol cement or calcium hydroxide was used as amputation material. The pulp reactions following the different treatments are discussed. If calcium hydroxide was used 90% was successful, while in cases with ZnO/eugenol cement as amputation material 8.9% developed necrosis of the pulp and 34.4% showed an undesirable reaction with formation of hard tissue barrier or obliteration. The healing frequency was 83.9% for teeth treated with pulpectomy but there was a clear correlation between the standard of the root filling and the success rate. For all three treatment groups there was a correlation between damage to the supportive tissue and treatment success.

Adolescent↗
PubMed2006

Tooth transplantation and cryopreservation: state of the art.

Autotransplantation of teeth is useful and has many indications in dentistry. Cryopreservation of teeth creates new possibilities--eg, when autotransplantation is needed, but the recipient site is too small and orthodontic treatment is needed to gain space for the transplant. This review article examines the reactions of various dental tissues after autotransplantation vs after autotransplantation with cryopreservation. Various subjects will be discussed, including periodontal healing, pulp reactions, and root development after autotransplantation with and without cryopreservation.

Animals↗
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↗
PubMedDate not supplied

Transgenic plants regenerated from hairy roots of Nicotiana benthamiana: a promising host for transient expression of foreign proteins.

Hairy root cultures of Nicotiana benthamiana have been obtained by co-cultivation of leaf explants with Agrobacterium rhizogenes strain A4 harboring a binary vector plasmid, and transgenic nature of the obtained cultures was confirmed by PCR analysis. Transgenic plants were regenerated from hairy roots. The biomass yield of transgenic plants grown in vitro was almost two-fold higher than those of wild-type N. benthamiana plants. They differed from untransformed plants by short internodes, reinforced stem, thick and wrinkled leaves and more developed root system. The level of Agrobacterium-mediated transient expression of green fluorescent protein (GFP) in the regenerated plants was similar to that of untransformed plants.

Agrobacterium tumefaciens↗
PubMed1996

Resumed tooth development following avulsion of a permanent central incisor.

A case is presented in which an upper right central incisor was avulsed because of trauma at age six. At the time of trauma it was suspected that the pulp had remained in the socket although the tooth had been lost. No attempt was made to treat the socket, remove the pulp, or replant the tooth. Follow-up radiography showed that, despite initial apparent complete loss of the calcified portion of the tooth, root development proceeded to completion.

Child↗
PubMed1997

The treatment of nonvital immature teeth with calcium hydroxide-sterile water paste: two case reports.

Death of the dental pulp before completion of root development results in a tooth with an open apex. During endodontic treatment, the open apex makes obturation difficult, because there is no apical stop against which the filling can be packed and condensed. For many years, open apices have been treated by root canal fillings or by periapical surgery with or without a reverse seal. Currently, the conservative approach is preferred over surgical management, to avoid the physical and psychological trauma of surgery to a young patient. Two patients were treated by calcium hydroxide-sterile water paste to promote the apexification of the nonvital teeth with an incompletely formed apex. Normal endodontic preparation of the canal had been carried out in the immature tooth. Radiologic examination after 6 to 9 months showed that the apex of the maxillary incisors was completed by newly formed tissue.

Calcium Compounds↗