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Electronic Apex Locator
An electronic apex locator is an electronic device used in endodontics to determine the position of the apical constriction and thus determine the length of the root canal space. The apex of the root has a specific resistance to electrical current, and this is measured using a pair of electrodes typically hooked into the lip and attached to an endodontic file. The electronic principle is relatively simple and is based on electrical resistance; when a circuit is complete (tissue is contacted by the tip of the file), resistance decreases markedly and current suddenly begins to flow. Various devices signal this event by a beep, a buzz, a flashing light, digital readouts, or a pointer on a dial. History and uses The original electronic apex locators operated on the direct current principle. A problem with these devices was that conductive fluids such as hemorrhage, exudate, or irrigant in the canal would permit current flow and therefore a false reading. Newer devices are impedance-bas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root Canal Meter
In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the surface of the soil, but roots can also be aerial or aerating, that is, growing up above the ground or especially above water. Function The major functions of roots are absorption of water, plant nutrition and anchoring of the plant body to the ground. Anatomy Root morphology is divided into four zones: the root cap, the apical meristem, the elongation zone, and the hair. The root cap of new roots helps the root penetrate the soil. These root caps are sloughed off as the root goes deeper creating a slimy surface that provides lubrication. The apical meristem behind the root cap produces new root cells that elongate. Then, root hairs form that absorb water and mineral nutrients from the soil. The first root in seed producing plants is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endodontics
Endodontics (from the Greek roots ''endo-'' "inside" and ''odont-'' "tooth") is the dental specialty concerned with the study and treatment of the dental pulp. Overview Endodontics encompasses the study (practice) of the basic and clinical sciences of normal dental pulp, the etiology, diagnosis, prevention, and treatment of diseases and injuries of the dental pulp along with associated periradicular conditions. In clinical terms, endodontics involves either preserving part, or all of the dental pulp in health, or removing all of the pulp in irreversible disease. This includes teeth with irreversibly inflamed and infected pulpal tissue. Not only does endodontics involve treatment when a dental pulp is present, but also includes preserving teeth which have failed to respond to non-surgical endodontic treatment, or for teeth that have developed new lesions, e.g., when root canal re-treatment is required, or periradicular surgery. Endodontic treatment is one of the most comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apical Constriction
Apical constriction is the process in which contraction of the apical side of a cell causes the cell to take on a wedged shape. Generally, this shape change is coordinated across many cells of an epithelial layer, generating forces that can bend or fold the cell sheet. Morphogenetic role Apical constriction plays a central role in important morphogenetic events in both invertebrates and vertebrates. It is typically the first step in any invagination process and is also important in folding tissues at specified hingepoints. During gastrulation in both invertebrates and vertebrates, apical constriction of a ring of cells leads to blastopore formation. These cells are known as bottle cells, for their eventual shape. Because all of the cells constrict on the apical side, the epithelial sheet bends convexly on the basal side. In vertebrates, apical constriction plays a role in a range of other morphogenetic processes such neurulation, placode formation, and primitive streak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Root Canal
A root canal is the naturally occurring anatomic space within the root of a tooth. It consists of the pulp chamber (within the coronal part of the tooth), the main canal(s), and more intricate anatomical branches that may connect the root canals to each other or to the surface of the root. Structure At the center of every tooth is a hollow area that houses soft tissues, such as the nerve, blood vessels, and connective tissue. This hollow area contains a relatively wide space in the coronal portion of the tooth called the pulp chamber. These canals run through the center of the roots, similar to the way graphite runs through a pencil. The pulp receives nutrition through the blood vessels, and sensory nerves carry signals back to the brain. A tooth can be relieved from pain if there is irreversible damage to the pulp, via root canal treatment. Root canal anatomy consists of the pulp chamber and root canals. Both contain the dental pulp. The smaller branches, referred to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Resistance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels with mechanical friction. The SI unit of electrical resistance is the ohm (), while electrical conductance is measured in siemens (S) (formerly called the 'mho' and then represented by ). The resistance of an object depends in large part on the material it is made of. Objects made of electrical insulators like rubber tend to have very high resistance and low conductance, while objects made of electrical conductors like metals tend to have very low resistance and high conductance. This relationship is quantified by resistivity or conductivity. The nature of a material is not the only factor in resistance and conductance, however; it also depends on the size and shape of an object because these properties are extensive rather than i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrodes
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials depending on the type of battery. The electrophore, invented by Johan Wilcke, was an early version of an electrode used to study static electricity. Anode and cathode in electrochemical cells Electrodes are an essential part of any battery. The first electrochemical battery made was devised by Alessandro Volta and was aptly named the Voltaic cell. This battery consisted of a stack of copper and zinc electrodes separated by brine-soaked paper disks. Due to fluctuation in the voltage provided by the voltaic cell it wasn't very practical. The first practical battery was invented in 1839 and named the Daniell cell after John Frederic Daniell. Still making use of the zinc–copper electrode combination. Since then many more batteries hav ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endodontic File
Endodontic files and reamers are surgical instruments used by dentists when performing root canal treatment. These tools A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates ba ... are used to clean and shape the root canal, with the concept being to perform complete chemomechanical debridement of the root canal to the length of the apical foramen. Preparing the canal in this way facilitates the chemical disinfection to a satisfactory length but also provides a shape conducive to obturation (filling of the canal). Hand files Hand files can provide tactile sensation when cleaning or shaping root canals. This allows the dentist to feel changes in resistance or angulation, which can help determine curvature, calcification and/or changes in anatomy, in which two dimensional radiographs m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiography
Radiography is an imaging technique using X-rays, gamma rays, or similar ionizing radiation and non-ionizing radiation to view the internal form of an object. Applications of radiography include medical radiography ("diagnostic" and "therapeutic") and industrial radiography. Similar techniques are used in airport security (where "body scanners" generally use backscatter X-ray). To create an image in conventional radiography, a beam of X-rays is produced by an X-ray generator and is projected toward the object. A certain amount of the X-rays or other radiation is absorbed by the object, dependent on the object's density and structural composition. The X-rays that pass through the object are captured behind the object by a detector (either photographic film or a digital detector). The generation of flat two dimensional images by this technique is called projectional radiography. In computed tomography (CT scanning) an X-ray source and its associated detectors rotate around ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apex Location
Apex location is a method of determining the length of the root canal of a tooth - manually or with a mechanical canal instrument that passes a low intensity electric current through the tooth. The electrical characteristics of the tooth structure are measured and the exact position of the instrument in the tooth is determined. When the tool tip touches the top of the tooth, the instrument signals that the apical foramen In dental anatomy, the apical foramen, literally translated "small opening of the apex," is the tooth's natural opening, found at the root's very tip—that is, the root's apex—whereby an artery, vein, and nerve enter the tooth and commingle w ... is reached. Whenever the channel instrument is pulled out its length can be measured to determine the depth of the root canal and all other dental tools can be adjusted to this length. Methods of measurement Method of Sonada The method of Sonada measures the canal's impedance using one or more electric frequenci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dental Equipment
Dental instruments are tools that dental professionals use to provide dental treatment. They include tools to examine, manipulate, treat, restore, and remove teeth and surrounding oral structures. Examination instruments These tools allow dental professionals to manipulate tissues for better visual access during treatment or during dental examination. Dental mirror The dentist or dental auxiliary use dental mirrors to view a mirror image of the teeth in locations of the mouth where visibility is difficult or impossible. They also are used for reflecting light onto desired surfaces, and for retraction of soft tissues to improve access or vision. Probes * Dental explorer (sickle probe) *Periodontal probe Retractors *Cheek retractor *Dental mirror *Lip retractor * Mouth prop *Tongue retractor Local anesthesia * Dental anesthesia and dental syringe Anesthesia is broken down into three main categories: local, regional, and general, all of which affect the nervous system in some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
