Tooth in the context of Cartilage

Injury is physiological damage to the living tissue of any organism, whether in humans, in other animals, or in plants.

Injuries can be caused in many ways, including mechanically with penetration by sharp objects such as teeth or with blunt objects, by heat or cold, or by venoms and biotoxins. Injury prompts an inflammatory response in many taxa of animals; this prompts wound healing. In both plants and animals, substances are often released to help to occlude the wound, limiting loss of fluids and the entry of pathogens such as bacteria. Many organisms secrete antimicrobial chemicals which limit wound infection; in addition, animals have a variety of immune responses for the same purpose. Both plants and animals have regrowth mechanisms which may result in complete or partial healing over the injury. Cells too can repair damage to a certain degree.

Ivory is a hard, white material from the tusks (traditionally from elephants) and teeth of animals, that consists mainly of dentin, one of the physical structures of teeth and tusks. The chemical structure of the teeth and tusks of mammals is the same, regardless of the species of origin, but ivory contains structures of mineralised collagen. The trade in certain teeth and tusks other than elephant is well established and widespread; therefore, "ivory" can correctly be used to describe any mammalian teeth or tusks of commercial interest which are large enough to be carved or scrimshawed.

Besides natural ivory, ivory can also be produced synthetically, hence (unlike natural ivory) not requiring the retrieval of the material from animals. Tagua nuts can also be carved like ivory.

Archaeopteryx (/ˌɑːrkiːˈɒptərɪks/ ; lit. 'ancient wing'), sometimes referred to by its German name, "Urvogel " (lit. 'Primeval Bird') is a genus of bird-like dinosaurs. The genus name derives from the Ancient Greek ἀρχαῖος (archaîos), meaning 'ancient', and πτέρυξ (ptérux), meaning 'feather, wing'. Between the late 19th century and the early 21st century, Archaeopteryx was generally accepted by palaeontologists and popular reference books as the oldest known bird (member of the group Avialae). Older potential avialans have since been identified, including Anchiornis, Xiaotingia, Aurornis, and Baminornis.

Archaeopteryx lived in the Late Jurassic around 150 million years ago, in what is now southern Germany, during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven, the largest species of Archaeopteryx could grow to about 50 cm (20 in) in length. Despite their small size, broad wings, and inferred ability to fly or glide, Archaeopteryx had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, they shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second toes ("killing claw"), feathers (which also suggest warm-bloodedness), and various features of the skeleton.

Osteichthyes (/ˌɒstiːˈɪkθiːz/ ost-ee-IK-theez; from Ancient Greek ὀστέον (ostéon) 'bone' and ἰχθύς (ikhthús) 'fish'), also known as osteichthyans or commonly referred to as the bony fish, is a diverse clade of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes (cartilaginous fish) and the extinct placoderms and acanthodians, which have endoskeletons primarily composed of cartilage. The vast majority of extant fish are members of Osteichthyes, being an extremely diverse and abundant group consisting of 45 orders, over 435 families and 28,000 species.

The group is divided into two main clades, the ray-finned fish (Actinopterygii, which makes up the vast majority of extant fish) and the lobe-finned fish (Sarcopterygii, which gave rise to all land vertebrates, i.e. tetrapods). The oldest known fossils of bony fish are about 425 million years old from the late Silurian, which are also transitional fossils showing a tooth pattern that is in between the tooth rows of sharks and true bony fishes. Despite the name, these early basal bony fish had not yet evolved ossification and their skeletons were still mostly cartilaginous, and the main distinguishing feature that set them apart from other fish clades were the development of foregut pouches that eventually evolved into the swim bladders and lungs, respectively.

Placoderms (from Ancient Greek πλάξ [plax, plakos] 'plate' and δέρμα [derma] 'skin') are vertebrate animals of the class Placodermi, an extinct group of prehistoric fish known from Paleozoic fossils during the Silurian and the Devonian periods. While their endoskeletons are mainly cartilaginous, their head and thorax were covered by articulated armoured plates (hence the name), and the rest of the body was scaled or naked depending on the species.

Placoderms were among the first jawed fish (their jaws likely evolved from the first pair of gill arches), as well as the first vertebrates to have true teeth. They were also the first fish clade to develop pelvic fins, the second set of paired fins and the homologous precursor to hindlimbs in tetrapods. 380-million-year-old fossils of three other genera, Incisoscutum, Materpiscis and Austroptyctodus, represent the oldest known examples of live birth.

Conodonts are an extinct group of marine jawless vertebrates belonging to the class Conodonta (from Ancient Greek κῶνος (kōnos), meaning "cone", and ὀδούς (odoús), meaning "tooth"). They are primarily known from their hard, mineralised tooth-like structures called "conodont elements" that in life were present in the oral cavity and used to process food. Rare soft tissue remains suggest that they had elongate eel-like bodies with large eyes. Conodonts were a long-lasting group with over 300 million years of existence from the Cambrian (over 500 million years ago) to the beginning of the Jurassic (around 200 million years ago). Conodont elements are highly distinctive to particular species and are widely used in biostratigraphy as indicative of particular periods of geological time.

Java Man (Homo erectus erectus, formerly also Anthropopithecus erectus or Pithecanthropus erectus) is an early human fossil discovered in 1891 and 1892 on the island of Java (Indonesia). Estimated to be between 700,000 and 1,490,000 years old, it was, at the time of its discovery, the oldest hominid fossil ever found, and it remains the type specimen for Homo erectus.

Led by Eugène Dubois, the excavation team uncovered a tooth, a skullcap, and a thighbone at Trinil on the banks of the Solo River in East Java. Arguing that the fossils represented the "missing link" between apes and humans, Dubois gave the species the scientific name Anthropopithecus erectus, then later renamed it Pithecanthropus erectus. The fossil aroused much controversy. Within a decade of the discovery almost eighty books or articles had been published on Dubois's finds. Despite Dubois's argument, few accepted that Java Man was a transitional form between apes and humans. Some dismissed the fossils as apes and others as modern humans, whereas many scientists considered Java Man as a primitive side branch of evolution not related to modern humans at all. In the 1930s Dubois made the claim that Pithecanthropus was built like a "giant gibbon", a much misinterpreted attempt by Dubois to prove that it was the "missing link". Eventually, similarities between Java Man and Sinanthropus pekinensis (Peking Man) led Ernst Mayr to rename both Homo erectus in 1950, placing them directly in the human evolutionary tree.

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 the mammal groups. The third molar of humans is sometimes vestigial.

The evolution of the horse, a mammal of the family Equidae, occurred over a geologic time scale of 50 million years, transforming the small, dog-sized, forest-dwelling Eohippus into the large, single-toed, modern-day horse. Paleozoologists have been able to piece together a more complete outline of the evolutionary lineage of the modern horse than of any other animal. Much of this evolution took place in North America, where horses originated but became extinct about 10,000 years ago, before being reintroduced in the 15th century.

The horse belongs to the order Perissodactyla (odd-toed ungulates), the members of which share hooved feet and an odd number of toes on each foot, as well as mobile upper lips and a similar tooth structure. This means that horses share a common ancestry with tapirs and rhinoceroses. The perissodactyls arose in the late Paleocene, less than 10 million years after the Cretaceous–Paleogene extinction event. This group of animals appears to have been originally specialized for life in tropical forests, but whereas tapirs and, to some extent, rhinoceroses, retained their jungle specializations, modern horses are adapted to life in the climatic conditions of the steppes, which are drier and much harsher than forests or jungles. Other species of Equus are adapted to a variety of intermediate conditions.

Scrimshaw is scrollwork, engravings, and carvings done in bone or ivory. Typically it refers to the artwork created by whalers, engraved on the byproducts of whales, such as bones or cartilage. It is most commonly made out of the bones and teeth of sperm whales, the baleen of other whales, and the tusks of walruses.

It takes the form of elaborate engravings in the form of pictures and lettering on the surface of the bone or tooth, with the engraving highlighted using a pigment, or, less often, small sculptures made from the same material. However, the latter typically fall into the categories of ivory carving, for all carved teeth and tusks, or bone carving. The making of scrimshaw probably began on whaling ships in the late 18th century and survived until the ban on commercial whaling. The practice survives as a hobby and as a trade for commercial artisans. A maker of scrimshaw is known as a scrimshander. The word first appeared in the logbook of the brig By Chance in 1826, but the etymology is uncertain.

In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, eye teeth, vampire teeth, or fangs, are the relatively long, pointed teeth. In the context of the upper jaw, they are also known as fangs. They can appear more flattened, however, causing them to resemble incisors and leading them to be called incisiform. They developed and are used primarily for firmly holding food in order to tear it apart, and occasionally as weapons. They are often the largest teeth in a mammal's mouth. Individuals of most species that develop them normally have four, two in the upper jaw and two in the lower, separated within each jaw by incisors; humans and dogs are examples. In most species, canines are the anterior-most teeth in the maxillary bone. The four canines in humans are the two upper maxillary canines and the two lower mandibular canines.They are specially prominent in dogs (Canidae), hence the name.

The phosphorus cycle is the biogeochemical cycle that involves the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based materials do not enter the gaseous phase readily, as the main source of gaseous phosphorus, phosphine, is only produced in isolated and specific conditions. Therefore, the phosphorus cycle is primarily examined studying the movement of orthophosphate (PO3−4), the form of phosphorus that is most commonly seen in the environment, through terrestrial and aquatic ecosystems.

Living organisms require phosphorus, a vital component of DNA, RNA, ATP, etc., for their proper functioning. Phosphorus also enters in the composition of phospholipids present in cell membranes. Plants assimilate phosphorus as phosphate and incorporate it into organic compounds. In animals, inorganic phosphorus in the form of apatite (Ca₅(PO₄)₃(OH,F)) is also a key component of bones, teeth (tooth enamel), etc. On the land, phosphorus gradually becomes less available to plants over thousands of years, since it is slowly lost in runoff. Low concentration of phosphorus in soils reduces plant growth and slows soil microbial growth, as shown in studies of soil microbial biomass. Soil microorganisms act as both sinks and sources of available phosphorus in the biogeochemical cycle. Short-term transformation of phosphorus is chemical, biological, or microbiological. In the long-term global cycle, however, the major transfer is driven by tectonic movement over geologic time and weathering of phosphate containing rock such as apatite. Furthermore, phosphorus tends to be a limiting nutrient in aquatic ecosystems. However, as phosphorus enters aquatic ecosystems, it has the possibility to lead to over-production in the form of eutrophication, which can happen in both freshwater and saltwater environments.

In dentistry, the crown is the visible part of the tooth above the gingival margin and is an essential component of dental anatomy. Covered by enamel, the crown plays a crucial role in cutting, tearing, and grinding food. Its shape and structure vary depending on the type and function of the tooth (incisors, canines, premolars, or molars), and differ between primary dentition and permanent dentition. The crown also contributes to facial aesthetics, speech, and oral health.

Placodonts ("tablet teeth") are an extinct order of marine reptiles that lived during the Triassic period, becoming extinct at the end of the period. They were part of Sauropterygia, the group that includes plesiosaurs. Placodonts were generally between 1 and 2 m (3 ft 3 in and 6 ft 7 in) in length, with some of the largest measuring 3 m (9.8 ft) long.

The first specimen was discovered in 1830. They have been found throughout central Europe, North Africa, the Middle East and China.

Periodontal disease, also known as gum disease, is a set of inflammatory conditions affecting the tissues surrounding the teeth. In its early stage, called gingivitis, the gums become swollen and red and may bleed. It is considered the main cause of tooth loss for adults worldwide. In its more serious form, called periodontitis, the gums can pull away from the tooth, bone can be lost, and the teeth may loosen or fall out. Halitosis (bad breath) may also occur.

Periodontal disease typically arises from the development of plaque biofilm, which harbors harmful bacteria such as Porphyromonas gingivalis and Treponema denticola. These bacteria infect the gum tissue surrounding the teeth, leading to inflammation and, if left untreated, progressive damage to the teeth and gum tissue. Recent meta-analysis have shown that the composition of the oral microbiota and its response to periodontal disease differ between men and women. These differences are particularly notable in the advanced stages of periodontitis, suggesting that sex-specific factors may influence susceptibility and progression. Factors that increase the risk of disease include smoking, diabetes, HIV/AIDS, family history, high levels of homocysteine in the blood and certain medications. Diagnosis is by inspecting the gum tissue around the teeth both visually and with a probe and X-rays looking for bone loss around the teeth.