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 or the mandible and are covered by gums. Teeth are made of multiple tissues of varying density and hardness.
Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.
Tooth decay, also known as cavities or caries, is the breakdown of teeth due to acids produced by bacteria. The cavities may be a number of different colors from yellow to black. Symptoms may include pain and difficulty with eating. Complications may include inflammation of the tissue around the tooth, tooth loss and infection or abscess formation.
Dentin or dentine is a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by enamel on the crown and cementum on the root and surrounds the entire pulp. By volume, 45% of dentin consists of the mineral hydroxyapatite, 33% is organic material, and 22% is water. Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel. Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel. Dentin rates approximately 3 on the Mohs scale of mineral hardness. There are two main characteristics which distinguish dentin from enamel: firstly, dentin forms throughout life; secondly, dentin is sensitive and can become hypersensitive to changes in temperature due to the sensory function of odontoblasts, especially when enamel recedes and dentin channels become exposed.
The pulp is the connective tissue, nerves, blood vessels, and odontoblasts that comprise the innermost layer of a tooth. The pulp's activity and signalling processes regulate its behaviour.
Ameloblasts are cells present only during tooth development that deposit tooth enamel, which is the hard outermost layer of the tooth forming the surface of the crown.
Bone canaliculi are microscopic canals between the lacunae of ossified bone. The radiating processes of the osteocytes project into these canals. These cytoplasmic processes are joined together by gap junctions. Osteocytes do not entirely fill up the canaliculi. The remaining space is known as the periosteocytic space, which is filled with periosteocytic fluid. This fluid contains substances too large to be transported through the gap junctions that connect the osteocytes.
The enamel organ, also known as the dental organ, is a cellular aggregation seen in a developing tooth and it lies above the dental papilla. The enamel organ which is differentiated from the primitive oral epithelium lining the stomodeum. The enamel organ is responsible for the formation of enamel, initiation of dentine formation, establishment of the shape of a tooth's crown, and establishment of the dentoenamel junction.
Tooth development or odontogenesis is the complex process by which teeth form from embryonic cells, grow, and erupt into the mouth. For human teeth to have a healthy oral environment, all parts of the tooth must develop during appropriate stages of fetal development. Primary (baby) teeth start to form between the sixth and eighth week of prenatal development, and permanent teeth begin to form in the twentieth week. If teeth do not start to develop at or near these times, they will not develop at all, resulting in hypodontia or anodontia.
Amelogenesis is the formation of enamel on teeth and begins when the crown is forming during the advanced bell stage of tooth development after dentinogenesis forms a first layer of dentin. Dentin must be present for enamel to be formed. Ameloblasts must also be present for dentinogenesis to continue.
In embryology and prenatal development, the dental papilla is a condensation of ectomesenchymal cells called odontoblasts, seen in histologic sections of a developing tooth. It lies below a cellular aggregation known as the enamel organ. The dental papilla appears after 8–10 weeks intra uteral life. The dental papilla gives rise to the dentin and pulp of a tooth.
Dentinogenesis is the formation of dentin, a substance that forms the majority of teeth. Dentinogenesis is performed by odontoblasts, which are a special type of biological cell on the outer wall of dental pulps, and it begins at the late bell stage of a tooth development. The different stages of dentin formation after differentiation of the cell result in different types of dentin: mantle dentin, primary dentin, secondary dentin, and tertiary dentin.
Pulpitis is inflammation of dental pulp tissue. The pulp contains the blood vessels, the nerves, and connective tissue inside a tooth and provides the tooth's blood and nutrients. Pulpitis is mainly caused by bacterial infection which itself is a secondary development of caries. It manifests itself in the form of a toothache.
An odontoblast process is an extension of a cell called an odontoblast, which forms dentin in a tooth. The odontoblast process is located in dentinal tubules. It forms during dentinogenesis and results from a part of the odontoblast staying in its location as the main body of the odontoblast moves toward the center of the tooth's pulp. The odontoblast process causes the secretion of hydroxyapatite crystals and mineralization of the matrix secreted by the odontoblasts.
Dentin hypersensitivity is dental pain which is sharp in character and of short duration, arising from exposed dentin surfaces in response to stimuli, typically thermal, evaporative, tactile, osmotic, chemical or electrical; and which cannot be ascribed to any other dental disease.
In dentistry, the hydrodynamic or fluid movement theory is one of three main theories developed to explain dentine hypersensitivity, which is a sharp, transient pain arising from stimuli exposure. It states that different types of stimuli act on exposed dentine, causing increased fluid flow through the dentinal tubules. In response to this movement, mechanoreceptors on the pulp nerves trigger the acute, temporary pain of dentine hypersensitivity.
Osteomodulin is a protein that in humans is encoded by the OMD gene.
Dentin sialophosphoprotein is a precursor protein for other proteins found in the teeth. It is produced by cells (odontoblasts) inside the teeth, and in smaller quantities by bone tissues. It is required for normal hardening (mineralisation) of teeth. During teeth development, it is broken down into three proteins such as dentin sialoprotein (DSP), dentin glycoprotein (DGP), and dentin phosphoprotein (DPP). These proteins become the major non-collagenous components of teeth. Their distribution in the collagen matrix of the forming dentin suggests these proteins play an important role in the regulation of mineral deposition. Additional evidence for this correlation is phenotypically manifested in patients with mutant forms of dentin sialophosphoprotein. Such patients suffer dental anomalies including type III dentinogenesis imperfecta.
Dentin sialoprotein is a protein found in teeth. It is one of the two proteins produced by the segmentation of dentin sialophosphoprotein. Dentin sialoprotein can be found in the dentin immediately subjacent to cellular cementum, but not subjacent to acellular fibrous cementum.
Pulp stones are nodular, calcified masses appearing in either or both the coronal and root portion of the pulp organ in teeth. Pulp stones are not painful unless they impinge on nerves.
