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Quad Helix
A quad helix (or quadhelix) is an orthodontic appliance for the upper teeth that is cemented in the mouth. It is attached to the molars by 2 bands and has two or four active helix A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, ... springs that widen the arch of the mouth to make room for crowded teeth, or correct a posterior cross-bite, where lower teeth are buccal (outer) than upper teeth. It is usually made from 38 mil stainless steel wire and is primarily indicated in mixed dentition, cleft patients and those that have performed the act of thumbsucking. A variety of this appliance is inserted into attachments that are welded to the bands. In this way the orthodontist can adjust the appliance without removing the bands. The precursor to the quad-helix was the coffin spring. Simil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthodontic
Orthodontics is a dentistry specialty that addresses the diagnosis, prevention, management, and correction of mal-positioned teeth and jaws, and misaligned bite patterns. It may also address the modification of facial growth, known as dentofacial orthopedics. Abnormal alignment of the teeth and jaws is very common. Nearly 50% of the developed world's population, according to the American Association of Orthodontics, has malocclusions severe enough to benefit from orthodontic treatment: although this figure decreases to less than 10% according to the same AAO statement when referring to medically necessary orthodontics. However, conclusive scientific evidence for the health benefits of orthodontic treatment is lacking, although patients with completed orthodontic treatment have reported a higher quality of life than that of untreated patients undergoing orthodontic treatment. Treatment may require several months to a few years, and entails using dental braces and other appliances t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Teeth
The human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food, the canines tear the food and the molars and premolars crush the food. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums. Teeth are made of multiple tissues of varying density and hardness. Humans, like most other mammals, are diphyodont, meaning that they develop two sets of teeth. The first set, deciduous teeth, also called "primary teeth", "baby teeth", or "milk teeth", normally eventually contains 20 teeth. Primary teeth typically start to appear (" erupt") around six months of age and this may be distracting and/or painful for the infant. However, some babies are born with o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Mouth
In human anatomy, the mouth is the first portion of the alimentary canal that receives food and produces saliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth. In addition to its primary role as the beginning of the digestive system, in humans the mouth also plays a significant role in communication. While primary aspects of the voice are produced in the throat, the tongue, lips, and jaw are also needed to produce the range of sounds included in speech. The mouth consists of two regions, the vestibule and the oral cavity proper. The mouth, normally moist, is lined with a mucous membrane, and contains the teeth. The lips mark the transition from mucous membrane to skin, which covers most of the body. Structure Oral cavity The mouth consists of two regions: the vestibule and the oral cavity proper. The vestibule is the area between the teeth, lips and cheeks. The oral cavity is bounded at the sides and in front by the alveolar pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molar (tooth)
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth", from ''mola'', millstone and ''dens'', tooth. Molars show a great deal of diversity in size and shape across mammal groups. The third molar of humans is sometimes vestigial. Human anatomy In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies from individual to individual. Race can also affect the age at which this occurs, with statistical variations between groups. In some cases, it may not even erupt at all. The human mouth contains upper (maxillary) and lower (mandib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helix
A helix () is a shape like a corkscrew or spiral staircase. It is a type of smooth space curve with tangent lines at a constant angle to a fixed axis. Helices are important in biology, as the DNA molecule is formed as two intertwined helices, and many proteins have helical substructures, known as alpha helices. The word ''helix'' comes from the Greek word ''ἕλιξ'', "twisted, curved". A "filled-in" helix – for example, a "spiral" (helical) ramp – is a surface called ''helicoid''. Properties and types The ''pitch'' of a helix is the height of one complete helix turn, measured parallel to the axis of the helix. A double helix consists of two (typically congruent) helices with the same axis, differing by a translation along the axis. A circular helix (i.e. one with constant radius) has constant band curvature and constant torsion. A ''conic helix'', also known as a ''conic spiral'', may be defined as a spiral on a conic surface, with the distance to the apex an expo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spring (device)
A spring is an elastic object that stores mechanical energy. In everyday use the term often refers to coil springs, but there are many different spring designs. Modern springs are typically manufactured from spring steel, although some non-metallic objects like the bow are also springs. When a conventional spring, without stiffness variability features, is compressed or stretched from its resting position, it exerts an opposing force approximately proportional to its change in length (this approximation breaks down for larger deflections). The ''rate'' or ''spring constant'' of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve. An extension or compression spring's rate is expressed in units of force divided by distance, for example or N/m or lbf/in. A torsion spring is a spring that works by twisting; when it is twisted about its axis by an angle, it produces a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coffin Spring
A coffin is a funerary box used for viewing or keeping a corpse, either for burial or cremation. Sometimes referred to as a casket, any box in which the dead are buried is a coffin, and while a casket was originally regarded as a box for jewelry, use of the word "casket" in this sense began as a euphemism introduced by the undertaker's trade. A distinction is commonly drawn between "coffins" and "caskets", using "coffin" to refer to a tapered hexagonal or octagonal (also considered to be anthropoidal in shape) box and "casket" to refer to a rectangular box, often with a split lid used for viewing the deceased as seen in the picture. Receptacles for cremated and cremulated human ashes (sometimes called cremains) are called urns. Etymology First attested in English in 1380, the word ''coffin'' derives from the Old French , from Latin , which means ''basket'', which is the latinisation of the Greek κόφινος (''kophinos''), ''basket''. The earliest attested form of the word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New Delhi
New Delhi (, , ''Naī Dillī'') is the capital of India and a part of the National Capital Territory of Delhi (NCT). New Delhi is the seat of all three branches of the government of India, hosting the Rashtrapati Bhavan, Parliament House, and the Supreme Court of India. New Delhi is a municipality within the NCT, administered by the NDMC, which covers mostly Lutyens' Delhi and a few adjacent areas. The municipal area is part of a larger administrative district, the New Delhi district. Although colloquially ''Delhi'' and ''New Delhi'' are used interchangeably to refer to the National Capital Territory of Delhi, both are distinct entities, with both the municipality and the New Delhi district forming a relatively small part of the megacity of Delhi. The National Capital Region is a much larger entity comprising the entire NCT along with adjoining districts in neighbouring states, including Ghaziabad, Noida, Gurgaon and Faridabad. The foundation stone of New Delhi was l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthodontic Appliances
Orthodontic technology is a specialty of dental technology that is concerned with the design and fabrication of dental appliances for the treatment of malocclusions, which may be a result of tooth irregularity, disproportionate jaw relationships, or both. There are three main types of orthodontic appliances: active, passive and functional. All these types can be fixed or removable. Active appliances An active appliance is a device used to apply forces to the teeth to change the relationship of the teeth. Removable active appliances Removable active appliances are intended for simple tipping movements. Use of removable appliances in modern orthodontics is much more limited than in the past due to their various shortcomings. * Expansion and labial segment alignment appliance (ELSAA) Fixed active appliances Edward Angle, regarded as the father of American orthodontics, developed many universal fixed active appliances, unifying orthodontic practice. * Begg lightwire applianc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
