Defense reactions of the pulp with special reference to circulation. An experimental study in rats.
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Contemporary treatment of uncomplicated and complicated crown fractures is presented in this article. New concepts and approaches are discussed in relation to modern research and new restorative materials. Practical suggestions for the recognition and clinical management of various types of crown fractures are described.
There are several problems related to the diagnosis and treatment of the acute painful tooth associated with a deep carious lesion, including the fact that there is little or no correlation between the clinical signs and symptoms and also that the diagnostic tools are not reliable. It is important to understand the problems experienced by dental practitioners and how they routinely make diagnosis and formulate treatment plans. The way general dental practitioners diagnosed, categorised and treated teeth with acute pain was ascertained by a questionnaire completed by practitioners attending postgraduate courses. The results indicate that dental radiographs and the dental history were most frequently used and that few practitioners had, and fewer used electric pulp testers. The concept of using simple clinical categories which correspond to treatment categories does not seem to be in widespread use, though the generally accepted role of calcium hydroxide as an indirect and direct capping material is widespread. The use of corticosteroid materials is not as widespread in younger practitioners as in their older colleagues and the use of emergency pulpotomy is infrequent.
The maxillary incisors occupy an extraordinary position in the dental arch. They set the aesthetic tone, and their influence on the overall well-being of the individual cannot be overemphasized. However, their eruptive pattern and dominance carries a significant risk for trauma, particularly in childhood. More than half of all traumatic dental injuries involve the central incisors. In the past, fractured teeth were either extracted, trimmed and leveled, or restored with cast restorations. The learning objective of this article is to stimulate a shift in treatment strategy towards aesthetic reattachment of fractured segments. Indications and limitations for reattachment are outlined, including the primary and secondary restorative efforts. Innovative operative techniques that improve the aesthetic, biologic, and mechanical variables of the reattachment treatment option are presented.
OBJECTIVES: The objective was to determine the effects of growth factor treatment on dental pulp cell sensitivity to toxicity. METHODS: The toxicity of zinc-containing and zinc-free dental amalgam was tested on four types of cells; glia, neurons, embryonic stem cells, and dental pulp cells. The effects of six different growth factors were tested on dental pulp cell sensitivity to amalgam toxicity. RESULTS: Zinc-containing amalgam was highly toxic to all cell types tested. Zinc-free amalgam was less toxic, but it was most toxic to dental pulp cells. Exposure of dental pulp cells to the growth factors IGF-I or BMP-7 had no effect on their morphology or rate of cell division, and did not alter their sensitivity to zinc-free amalgam toxicity. Exposure to EGF, bFGF, or TGF-beta altered the morphology and decreased the rate of cell division, and the cells were no longer sensitive to zinc-free amalgam toxicity. Exposure to BMP-2 also altered the morphology and decreased the rate of cell division, but the cells remained sensitive to zinc-free amalgam toxicity. SIGNIFICANCE: The results indicate that untreated dental pulp cells are highly sensitive to amalgam toxicity, but that sensitivity can be decreased by exposure to certain growth factors. Therefore, for treatment of conditions in which pulp cells may come in contact with substances released from dental materials, such as pulp capping, the use of amalgam should be avoided unless the pulp cells are first treated with the proper growth factors.
Homeobox-containing genes play a crucial role in odontogenesis. After the detection of Dlx and Msx genes in overlapping domains along maxillary and mandibular processes, a homeobox odontogenic code has been proposed to explain the interaction between different homeobox genes during dental lamina patterning. No role has so far been assigned to the Hox gene network in the homeobox odontogenic code due to studies on specific Hox genes and evolutionary considerations. Despite its involvement in early patterning during embryonal development, the HOX gene network, the most repeat-poor regions of the human genome, controls the phenotype identity of adult eukaryotic cells. Here, according to our results, the HOX gene network appears to be active in human tooth germs between 18 and 24 weeks of development. The immunohistochemical localization of specific HOX proteins mostly concerns the epithelial tooth germ compartment. Furthermore, only a few genes of the network are active in embryonal retromolar tissues, as well as in ectomesenchymal dental pulp cells (DPC) grown in vitro from adult human molar. Exposure of DPCs to cAMP induces the expression of from three to nine total HOX genes of the network in parallel with phenotype modifications with traits of neuronal differentiation. Our observations suggest that: (i) by combining its component genes, the HOX gene network determines the phenotype identity of epithelial and ectomesenchymal cells interacting in the generation of human tooth germ; (ii) cAMP treatment activates the HOX network and induces, in parallel, a neuronal-like phenotype in human primary ectomesenchymal dental pulp cells.
The exposure of dental pulp generally occurs as the result of accidental trauma or preparation techniques utilized during the restoration of carious lesions. While frank carious exposures are optimally treated with pulpectomy and root canal therapy, the ideal treatment of mechanically exposed pulps has remained controversial. This article describes the indications, clinical techniques, and prognosis for direct pulp capping and partial pulpotomy.
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A series of deep cavities with and without traumatic pulpal exposures were prepared in the maxillary molars of albino rats. They were left untreated for various time intervals before killing. Demineralized sections were prepared in a mesiodistal plane and stained to demonstrate the presence of bacteria. In the cavities and coronal pulps that were grossly contaminated, bacteria were detected in the majority of sections. In the root canals and periapical tissues, bacteria were detected in only a minority of sections. It is considered that serial sections stained to demonstrate bacteria are necessary for the detection of bacteria that are present in only small numbers in the tissues. The demonstration of small numbers of micro-organisms in specific zones of the pulp remains problematic. Failure to detect stained bacteria in histological sections is not absolute proof of their absence.
Exposure of the dental pulp, through a caries lesion, accidentally during routine cavity preparation, or as a result of tooth fracture, is a clinical reality that requires optimal treatment. The potential for healing by formation of a dentinal bridge is good, provided that the pulp is not inflamed. Calcium hydroxide has a long history of inducing dentinal bridge formation to promote successful healing. Resin composites are emerging as alternative materials for pulp capping, but healing is slower, and relatively little clinical experience is available for analysis. The prognosis for healing is poor after exposure of an inflamed pulp. Pulpotomy should be considered to create a wound in an uninflamed location. If an exposure is expected through a caries lesion, stepwise excavation of the carious dentin should be considered to allow healing of the dentin and pulp prior to the final excavation of the carious dentin.
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AIM: The purpose of this study was to collect quantitative information about the numbers and dentine bridge secretory activity of odontoblast-like cells following dental pulp exposure. METHODOLOGY: The numbers and secretory activity of odontoblast-like cells were measured histomorphometrically between 7 days and 2 years in 161 pulp-exposed nonhuman primate teeth. The area of dentine bridges and the dimensions of cavity preparations were measured. The density of odontoblast-like cells and subjacent reorganizing tissue cells were measured beneath dentine bridge formation. The presence of operative dentine debris and tunnel defects in bridges was noted. Pulp inflammation was categorized according to ISO standards. Bacteria were detected using McKay's stain. RESULTS: The area of dentine bridges was mediated by the density and secretory activity of odontoblast-like cells over time. The cell density of subjacent reorganizing tissue was found to be strongly associated with that of odontoblast-like cells. Bacterial microleakage was found to impede dentine bridge secretion by odontoblast-like cells. CONCLUSIONS: Pulp reparative activity occurs naturally beneath capping materials in the absence of bacterial microleakage. The outcome of pulp-capping treatments could be beneficially influenced by concentrating attention on limiting the width of pulp exposure, minimizing pulp injury by limiting the creation of operative debris and placing materials which prevent bacterial microleakage.
The near red-pulsed erbium, chromium:yttrium-scandium-gallium-garnet laser hydrokinetic system, or Er,Cr:YSGG laser HKS, is effective in cutting dental hard tissues. In this longitudinal study, the authors studied the continuously erupting open-apex incisors of New Zealand albino rabbits and the constricted apex teeth of beagles to determine the effects of HKS-produced lesions at various energy levels and of preparations produced by a tapered fissure bur on dental pulp. No pulpal inflammatory responses could be identified either immediately or 30 days after surgery in HKS preparations that removed enamel and dentin without pulp exposure.
The effects of antibacterial drugs on bacterially contaminated dental pulps were investigated in monkeys. Class V buccal cavities with pulpal exposures were prepared and then left open to the oral environment for 24 h. The exposed pulps were capped with alpha-tricalcium phosphate (alpha-TCP) containing a mixture of antibacterial drugs. Either alpha-TCP or Ca(OH)2 was used as a control. Pulpal responses were histologically evaluated after 4 wk. Those teeth capped with alpha-TCP alone showed total pulp necrosis and bacterial growth within the pulp chamber. By contrast, the pulps capped with alpha-TCP containing mixed antibacterial drugs remained almost normal without any necrotic layer, but showed persistent absorbing response to capping materials and no signs of hard tissue barrier formation. In teeth capped with Ca(OH)2, a hard tissue barrier was formed below the exposure site, with a wide loss of pulp tissue. No inflammation was seen under the barrier. These results indicate that mixed antibacterial drugs added to alpha-TCP effectively disinfected pulpal lesions, without destroying any of the sound pulp tissue. However, hard tissue barrier formation was delayed by this mixture as compared with Ca(OH)2.