Maxillary first molar
The maxillary first molar is the human tooth located laterally from both the maxillary second premolars of the mouth but mesial from both maxillary second molars. The function of this molar is similar to that of all molars in regard to grinding being the principal action during mastication known as chewing. There are four cusps on maxillary molars, two on the buccal and two palatal. There may be a fifth smaller cusp on the palatal side known as the Cusp of Carabelli. Maxillary molars have four lobes, two buccal and two lingual, which are named in the same manner as the cusps that represent them. Unlike the anterior teeth and premolars, molars do not exhibit facial developmental depressions. Evidence of lobe separation can be found in the central groove, which divides buccal from lingual lobes; the two lingual lobes are separated by the distolingual groove, the two buccal lobes are divided by the buccal groove. There are great differences between the deciduous maxillary molars and those of the permanent maxillary molars though their function are similar.
The permanent maxillary molars are not considered to have any teeth. Despite being named molars, the deciduous molars are followed by permanent premolars. Permanent maxillary first molar notation In the universal numbering system, one number is used to identify the tooth; the right permanent maxillary first molar is known as tooth "3", the left permanent maxillary first molar is known as tooth "14". In the Palmer notation, a number and symbol are used to identify the tooth; the number identifies the tooth position relative to the midline, the symbol identifies the quadrant of the mouth. Both maxillary first molars have the same number. However, the right molar has the symbol "┘" underneath it; the left molar has "└" underneath it. In the international system of notation two numbers are used to identify the tooth; the first number identifies the quadrant of the mouth. The second number identifies the tooth relative to the midline of the arch; the right permanent maxillary first molar is known as "16".
The left permanent maxillary first molar is known as "26". Deciduous maxillary first molar notation In the universal numbering system, an uppercase letter is used to identify the tooth; the right deciduous maxillary first molar is known as "B", the left one is known as "I". In the Palmer notation, a letter and symbol are used to identify the tooth; the letter identifies the tooth position relative to the midline, the symbol identifies the quadrant of the mouth. Both maxillary first molars have the same letter; the left molar has "└" underneath it. In the international system of notation two numbers are used to identify the tooth; the right deciduous maxillary first molar is known as "54", the left one is known as "64". The maxillary first molar has three roots; the mesiobuccal root is broad distobuccal and has prominent depressions or flutings on its mesial and distal surfaces. The internal canal morphology is variable, but the majority of the mesiobuccal roots contain two canals; the distobuccal root is rounded or ovoid in cross section and contains a single canal.
The palatal root is more broad mesiodistally than buccolingually and ovoidal in shape but contains only a single canal. Although the palatal root appears straight on radiographs, there is a buccal curvature in the apical third. Depressions on the buccal and palatal surfaces of the palatal root can be present but are shallow. There are prominent depressions found on the distal aspect of the mesiobuccal roots. Depressions can be found on the furcal side of the distobuccal and palatal roots; the overall average length of the maxillary first molar is 20.5 mm with an average crown length of 7.5 mm and an average root length of 13 mm. The maxillary first molars are the second most common carious teeth and the second most common teeth to undergo endodontic treatment or extraction. Up to 21% of all extracted teeth are maxillary first molars
Vicat softening point
Vicat softening temperature or Vicat hardness is the determination of the softening point for materials that have no definite melting point, such as plastics. It is taken as the temperature at which the specimen is penetrated to a depth of 1 mm by a flat-ended needle with a 1 mm2 circular or square cross-section. For the Vicat A test, a load of 10 N is used. For the Vicat B test, the load is 50 N. Standards to determine Vicat softening point include ASTM D 1525 and ISO 306, which are equivalent; the vicat softening temperature can be used to compare the heat-characteristics of different materials. Four different methods may be used for testing. ISO 10350 Note ISO 10350 Vicat values are tested using the B50 method. Similar Standards: ASTM D1525
British Standard Pipe
British Standard Pipe is a family of technical standards for screw threads, adopted internationally for interconnecting and sealing pipes and fittings by mating an external thread with an internal thread. It has been adopted as standard in plumbing and pipe fitting, except in the United States, where NPT and related threads are the standard used. Two types of threads are distinguished: Parallel threads, British Standard Pipe Parallel thread, which have a constant diameter; these can be combined into two types of joints: Jointing threads These are pipe threads where pressure-tightness is made through the mating of two threads together. They always can have either parallel or taper female threads. Longscrew threads These are parallel pipe threads used where a pressure-tight joint is achieved by the compression of a soft material between the end face of the male thread and a socket or nipple face, with the tightening of a backnut; the thread form follows the British Standard Whitworth standard: Symmetrical V-thread in which the angle between the flanks is 55° One-sixth of this sharp V is truncated at the top and the bottom The threads are rounded at crests and roots by circular arcs ending tangentially with the flanks where r ≈ 0.1373P The theoretical depth of the thread is therefore 0.6403 times the nominal pitch h ≈ 0.6403P At least 41 thread sizes have been defined, ranging from 1⁄16 to 18, although of these only 15 are included in ISO 7 and 24 in ISO 228.
The size number was based on the inner diameter of a steel tube for which the thread was intended, but contemporary pipes tend to use thinner walls to save material, thus have an inner diameter larger than this nominal size. In the modern standard metric version, it is a size number, where listed diameter size is the major outer diameter of the external thread. For a taper thread, it is the diameter at the "gauge length" from the small end of the thread; the taper is 1 to 16, meaning that for each 16 units of measurement increase in the distance from the end, the diameter increases by 1 unit of measurement. These standard pipe threads are formally referred to by the following sequence of blocks: the words, Pipe thread, the document number of the standard the symbol for the pipe thread type: G, external and internal parallel R, external taper Rp, internal parallel Rc, internal taper Rs, external parallel the thread sizeThreads are right-hand. For left-hand threads, the letters, LH, are appended.
Example: Pipe thread EN 10226 Rp 2 1⁄2 The terminology for the use of G and R originated from Germany The standard ISO 7 - Pipe threads where pressure-tight joints are made on the threads consists of the following parts: ISO 7-1:1994 Dimensions and designation ISO 7-2:2000 Verification by means of limit gauges The standard ISO 228 - Pipe threads where pressure-tight joints are not made on the threads consists of the following parts: ISO 228-1:2000 Dimensions and designation ISO 228-2:1987 Verification by means of limit gauges British Standard Pipe Parallel Thread Dimensions British Standard Pipe Taper Thread Dimensions ISO 7-1:1994 ISO 7-2:2000 ISO 228-1:2000 ISO 228-2:1987
A wisdom tooth or third molar is one of the three molars per quadrant of the human dentition. It is the most posterior of the three; the age at which wisdom teeth come through is variable, but occurs between late teens and early twenties. Most adults have four wisdom teeth, one in each of the four quadrants, but it is possible to have none, fewer, or more, in which case the extras are called supernumerary teeth. Wisdom teeth may get stuck against other teeth if there is not enough space for them to come through normally. While this does not cause movement of other teeth, it can cause tooth decay if the impaction makes oral hygiene difficult. Wisdom teeth which are erupted through the gum may cause inflammation and infection in the surrounding gum tissues, termed pericoronitis. Wisdom teeth are extracted when or before these problems occur; however some recommend against the prophylactic extraction of disease-free impacted wisdom teeth. Agenesis of wisdom teeth differs by population, ranging from zero in Aboriginal Tasmanians to nearly 100% in indigenous Mexicans.
The difference is related to the PAX9, MSX1 gene. There is significant variation between the reported age of eruption of wisdom teeth between different populations. For example, wisdom teeth tend to erupt earlier in black people compared to white people. Wisdom teeth are stated as erupting most between age 17 and 21. Eruption may start as early as age 13 in some groups. Sometimes they can erupt up to age 25. If they have not erupted by age 25, oral surgeons consider that the tooth will not erupt spontaneously by itself. Wisdom teeth are vestigial third molars, it is thought that the skulls of human ancestors had larger jaws with more teeth, which helped to chew foliage to compensate for a lack of ability to efficiently digest the cellulose that makes up a plant cell wall. After the advent of agriculture over 10,000 years ago, soft human diets became the norm, including carbohydrate and high energy foods; such diets result in jaws growing with less forward growth than our paleolithic ancestors and not enough room for the wisdom teeth.
Wisdom teeth have long been identified as a source of problems and continue to be the most impacted teeth in the human mouth. The oldest known impacted wisdom tooth belonged to a European woman of the Magdalenian period. A lack of room to allow the teeth to erupt results in a risk of periodontal disease and dental cavities that increases with age. Less than 2% of adults age 65 years or older maintain the teeth without cavities or periodontal disease and 13% maintain unimpacted wisdom teeth without cavities or periodontal disease. Impacted wisdom teeth are classified by the direction and depth of impaction, the amount of available space for tooth eruption and the amount soft tissue or bone that covers them; the classification structure allows clinicians to estimate the probabilities of impaction and complications associated with wisdom teeth removal. Wisdom teeth are classified by the presence of symptoms and disease. Treatment of an erupted wisdom tooth is the same as any other tooth in the mouth.
If impacted, treatment can be localized to the infected tissue overlying the impaction, extraction or coronectomy. Although formally known as third molars, the common name is wisdom teeth because they appear so late – much than the other teeth, at an age where people are "wiser" than as a child, when the other teeth erupt; the term came as a translation of the Latin dens sapientiae. Their eruption has been known to cause dental issues for millennia. Cases have been known in women upwards of eighty years old where at the close of life the wisdom-teeth have come up, causing great pain in their coming; this happens, when it does happen, in the case of people where the wisdom-teeth have not come up in early years. Nonetheless, molar impaction was rare prior to the modern era. With the Industrial Revolution, the affliction became ten times more common, owing to the new prevalence of soft and sugary foods. National Institute of Clinical Health and Excellence Guideline to Wisdom teeth removal Wisdom tooth extraction WebMD article
Permanent teeth or adult teeth are the second set of teeth formed in diphyodont mammals. In humans and old world simians, there are thirty-two permanent teeth, consisting of six maxillary and six mandibular molars, four maxillary and four mandibular premolars, two maxillary and two mandibular canines, four maxillary and four mandibular incisors; the first permanent tooth appears in the mouth at around six years of age, the mouth will be in a transition time with both primary teeth and permanent teeth during the mixed dentition period until the last primary tooth is lost or shed. The first of the permanent teeth to erupt are the permanent first molars, right behind the last'milk' molars of the primary dentition; these first permanent molars are important for the correct development of a permanent dentition. Up to the age of thirteen years, twenty-eight of the thirty-two permanent teeth will appear; the full permanent dentition is completed much during the permanent dentition period. The four last permanent teeth, the third molars appear between the ages of 17 and 38 years.
It is possible to have extra, or "supernumerary," teeth. This phenomenon is called hyperdontia and is erroneously referred to as "a third set of teeth." These teeth may remain impacted in the bone. Hyperdontia is associated with syndromes such as cleft lip and palate, trichorhinophalangeal syndrome, cleidocranial dysplasia, Gardner's syndrome. Deciduous dentition Tooth development Tooth eruption Ash, Major M. and Stanley J. Nelson, 2003. Wheeler’s Dental Anatomy and Occlusion. 8th edition. This article incorporates text in the public domain from the 20th edition of Gray's Anatomy Permanent dentition - Adult teeth chart Morphology permanent teeth
Deciduous teeth known as milk teeth, baby teeth and temporary teeth, are the first set of teeth in the growth development of humans and other diphyodont mammals. They develop during the embryonic stage of development and erupt—that is, they become visible in the mouth—during infancy, they are lost and replaced by permanent teeth, but in the absence of permanent replacements, they can remain functional for many years. Primary teeth start to form during the embryo phase of human life; the development of primary teeth starts at the sixth week of tooth development as the dental lamina. This process starts at the midline and spreads back into the posterior region. By the time the embryo is eight weeks old, there are ten buds on the upper and lower arches that will become the primary dentition; these teeth will continue to form. In the primary dentition there are ten per arch; the eruption of these teeth begins at the age of six months and continues until twenty-five to thirty-three months of age during the primary dentition period.
The first teeth seen in the mouth are the mandibular centrals and the last are the maxillary second molars. The primary teeth are made up of central incisors, lateral incisors, first molars, secondary molars. All of these are replaced with a permanent counterpart except for the primary first and second molars; the replacement of primary teeth begins around age six, when the permanent teeth start to appear in the mouth, resulting in mixed dentition. The erupting permanent teeth cause root resorption, where the permanent teeth push on the roots of the primary teeth, causing the roots to be dissolved by odontoclasts and become absorbed by the forming permanent teeth; the process of shedding primary teeth and their replacement by permanent teeth is called exfoliation. This may last from age six to age twelve. By age twelve there are only permanent teeth remaining. However, it is not rare for one or more primary teeth to be retained beyond this age, sometimes well into adulthood because the secondary tooth fails to develop.
Teething age of primary teeth: Central incisors: 6–12 months Lateral incisors: 9–16 months First molars: 13–19 months Canine teeth: 16–23 months Second molars: 22–33 months Primary teeth are essential in the development of the mouth. The primary teeth maintain the arch length within the jaw, the bone and the permanent teeth replacements develop from the same tooth germs as the primary teeth; the primary teeth provide guides for the eruption pathway of the permanent teeth. The muscles of the jaw and the formation of the jaw bones depend on the primary teeth to maintain proper spacing for permanent teeth; the roots of primary teeth provide an opening for the permanent teeth to erupt. The primary teeth are important for the development of the child's speech, for the child's smile and play a role in chewing of food, although children who have had their primary teeth removed can still eat and chew to a certain extent. In all European languages the primary teeth are called "baby teeth" or "milk teeth".
In the United States and Canada, the term "baby teeth" is common. In some Asian countries they are referred to as "fall teeth" since they will fall out. Although shedding of a milk tooth is predominantly associated with positive emotions such as pride and joy by the majority of the children, socio-cultural factors affect the various emotions children experience during the loss of their first primary tooth. Various cultures have customs relating to the loss of deciduous teeth. In English-speaking countries, the tooth fairy is a popular childhood fiction that a fairy rewards children when their baby teeth fall out. Children place a tooth under their pillow at night; the fairy is said to replace it with money or small gifts while they sleep. In some parts of Australia and Norway, the children put the tooth in a glass of water. In medieval Scandinavia there was a similar tradition, surviving to the present day in Iceland, of tannfé, a gift to a child when it cuts its first tooth. In Nigeria, the Igbo in a similar custom expects a visiting relative or guest to make a gift or donation to an infant upon the visitor's sighting of the infant's deciduous teeth.
Hausa culture has it that a child with a fallen tooth should not let a lizard see his or her toothless gum because if a lizard does see it, no tooth will grow in its place. Other traditions are associated with mice or other rodents because of their sharp, everlasting teeth; the character Ratón Pérez appears in the tale of The Vain Little Mouse. A Ratoncito Pérez was used by Colgate in marketing toothpaste in Spain. In Italy, the Tooth Fairy is often replaced by a small mouse. In France and in French-speaking Belgium, this character is called la petite souris. From parts of lowland Scotland comes a tradition similar to the fairy mouse: a white fairy rat who purchases the teeth with coins. Several traditions concern throwing the shed teeth. In Turkey and Greece, children traditionally throw their fallen baby teeth onto the roof of their house while making a wish. In some Asian countries, such as India, Nepal, the Philippines, Vietnam, when a child loses a tooth, the usual custom is that he or she should throw it onto the roof if it came from the lower jaw, or into the space beneath the floor if it came fr
International Organization for Standardization
The International Organization for Standardization is an international standard-setting body composed of representatives from various national standards organizations. Founded on 23 February 1947, the organization promotes worldwide proprietary and commercial standards, it is headquartered in Geneva and works in 164 countries. It was one of the first organizations granted general consultative status with the United Nations Economic and Social Council; the International Organization for Standardization is an independent, non-governmental organization, the members of which are the standards organizations of the 164 member countries. It is the world's largest developer of voluntary international standards and facilitates world trade by providing common standards between nations. Over twenty thousand standards have been set covering everything from manufactured products and technology to food safety and healthcare. Use of the standards aids in the creation of products and services that are safe, reliable and of good quality.
The standards help businesses increase productivity while minimizing errors and waste. By enabling products from different markets to be directly compared, they facilitate companies in entering new markets and assist in the development of global trade on a fair basis; the standards serve to safeguard consumers and the end-users of products and services, ensuring that certified products conform to the minimum standards set internationally. The three official languages of the ISO are English and Russian; the name of the organization in French is Organisation internationale de normalisation, in Russian, Международная организация по стандартизации. ISO is not an acronym; the organization adopted ISO as its abbreviated name in reference to the Greek word isos, as its name in the three official languages would have different acronyms. During the founding meetings of the new organization, the Greek word explanation was not invoked, so this meaning may have been made public later. ISO gives this explanation of the name: "Because'International Organization for Standardization' would have different acronyms in different languages, our founders decided to give it the short form ISO.
ISO is derived from the Greek isos, meaning equal. Whatever the country, whatever the language, the short form of our name is always ISO."Both the name ISO and the ISO logo are registered trademarks, their use is restricted. The organization today known as ISO began in 1928 as the International Federation of the National Standardizing Associations, it was suspended in 1942 during World War II, but after the war ISA was approached by the formed United Nations Standards Coordinating Committee with a proposal to form a new global standards body. In October 1946, ISA and UNSCC delegates from 25 countries met in London and agreed to join forces to create the new International Organization for Standardization. ISO is a voluntary organization whose members are recognized authorities on standards, each one representing one country. Members meet annually at a General Assembly to discuss ISO's strategic objectives; the organization is coordinated by a Central Secretariat based in Geneva. A Council with a rotating membership of 20 member bodies provides guidance and governance, including setting the Central Secretariat's annual budget.
The Technical Management Board is responsible for over 250 technical committees, who develop the ISO standards. ISO has formed two joint committees with the International Electrotechnical Commission to develop standards and terminology in the areas of electrical and electronic related technologies. ISO/IEC Joint Technical Committee 1 was created in 1987 to "evelop, maintain and facilitate IT standards", where IT refers to information technology. ISO/IEC Joint Technical Committee 2 was created in 2009 for the purpose of "tandardization in the field of energy efficiency and renewable energy sources". ISO has 163 national members. ISO has three membership categories: Member bodies are national bodies considered the most representative standards body in each country; these are the only members of ISO. Correspondent members are countries; these members do not participate in standards promulgation. Subscriber members are countries with small economies, they can follow the development of standards. Participating members are called "P" members, as opposed to observing members, who are called "O" members.
ISO is funded by a combination of: Organizations that manage the specific projects or loan experts to participate in the technical work. Subscriptions from member bodies; these subscriptions are in proportion to each country's gross national trade figures. Sale of standards. ISO's main products are international standards. ISO publishes technical reports, technical specifications, publicly available specifications, technical corrigenda, guides. International standards These are designated using the format ISO nnnnn: Title, where nnnnn is the number of the standard, p is an optional part number, yyyy is the year published, Title describes the subject. IEC for International Electrotechnical Commission is included if the standard results from the work of ISO/IEC JTC1. ASTM is used for standards developed in cooperation with ASTM International. Yyyy and IS are not used for an incomplete or unpublished standard and may under some