Development of teeth-1

The primitive oral cavity is also known as the	Stomodeum
The epithelial lining of the primitive oral cavity is best described as	Stratified squamous epithelium
The buccopharyngeal membrane is formed by	Oral ectoderm and endoderm of foregut
The buccopharyngeal membrane ruptures & the primitive oral cavity establishes a connection with the foregut at about the	27th day of gestation
The dental lamina forms when the human embryo is	6 weeks old
The dental lamina serves as a primodium for the	Ectodermal portion of teeth. It serves as a primodium for the ectodermal portion of the deciduous teeth.
The development of the 1st permanent molar is initiated at	4th month intrauterine life
The development of the 2nd permanent molar is initiated at	1st yr after birth
The bud of non-successional permanent teeth develops from lamina due to	Distal proliferation. Or as a distal extension of the dental lamina. Sometimes this distal extension extend deep in to the ramus causing the development of teeth (especially third molars) in the ramus.
The bud of successional permanent teeth develops from lamina due to	Lingual proliferation.  Or as a lingual extension of the free end of the dental lamina opposite to the enamel organ of each deciduous teeth.
The development of successional lamina extends from	Fifth month intrauterine life  to 10 months of age
The activity of the dental lamina extends over a period of at least	5years
The vestibular lamina is located _________ to the dental lamina	Buccal
The lip furrow band is also known as	Vestibular lamina
The first deciduous tooth bud to be formed is in the	Anterior maxilla
The development stages of teeth are named after the shape of	Epithelial component
In bud stage of teeth development, enamel organ consists of	Peripheral low columnar cells & central polygonal cells
The local grouping of ectomesenchymal cells that fails to produce extracellular substances and not separated from each other in and around the enamel organ is referred to as the	Condensation. Induction is the ability to induce changes or differentiation. Maturation is the cells attaining the features and characteristics it was designed to show and differentiation is the ability of a group of developing cells to change from one group to other with new characteristics under some influence.
The area of ectomesenchymal condensation sub adjacent (below) to enamel organ is	Dental papilla
The condensed ectomesenchyme that surrounds the tooth bud is the	Dental sac
The dental papilla will give rise to	Pulp and dentin. By the inductive effect of the inner enamel epithelium, the superficial ectomesenchymal cells of dental papilla differentiate in to odontoblasts that form the dentin.
The dental sac will give rise to	Cementum and periodontal ligament. Once the epithelial root sheath of Hertwig is broken the newly formed radicular or root dentin is exposed and exerts an inductive influence on the dental sac or follicle cells to form the cementoblast and the periodontal ligament.
Cap stage is the stage where the enamel organ undergoes	Proliferation. Unequal proliferation and enlargement of the enamel organ and tooth bud is a characteristic feature of the stage. The type and place of proliferation depends upon the type of teeth.
In cap stage of teeth development, the inner enamel epithelium is	Tall columnar and in concavity
In cap stage of teeth development, the outer enamel epithelium is	Cuboidal and in convexity
During odontogenesis, the layer which has a cushion like consistency & gives support to the delicate enamel forming cells is the	Stellate reticulum
Parts of tooth bud	Epithelium and central cell
Parts of enamel organ	Inner and outer enamel epithelium, stellate reticulum and stratum intermedium
The enamel pulp of the enamel organ is also called	Stellate reticulum
Stellate reticulum in bell stage of odontogenesis is rich in	Albumin. Inner dental epithelium demonstrates high quantities of glycogen, Stratum intermedium is rich in alkaline phosphatase and capillaries do not come inside this epithelial part of the tooth bud. The cells of stellate reticulum are formed by the fluid accumulation between the polygonal cells of the tooth bud. They assume a branched reticular form and rich in albumin content turning them mucoid or mucinous. This gives a cushioning effect as well as to serve for increased nutritional demand latter.
Structure in enamel organ that does not disappear before enamel formation begins is	Enamel cord and Enamel knot
A localized, transient epithelial thickening of inner enamel epithelium in bell stage of odontogenesis is	Enamel knot
A localized, linear, transient epithelial thickening of inner enamel epithelium extending to outer enamel epithelium in bell stage of odontogenesis is	Enamel cord. It is also known as the enamel septum that divides the tooth in to two halves and is reported to be involved in the determination of the initial position of the first cusp to be formed and by cusp pattern by differential cell division. Enamel niche is an artifact created by the plane of section, where it creates an illusion of a tooth germ having a double attachment by a double strand.
The layer of cells which have been demonstrated to have a high degree of metabolic activity in bell stage of teeth development is the	Stratum intermedium. Well developed cytoplasmic organelles, high amounts of acid mucopolysaccharides and glycogen deposits indicate the high metabolic activity that is carried out in this layer.
The inner enamel epithelium differentiates in to the ameloblasts in the	Late bell stage
The organizing influence of the inner enamel epithelium on the surrounding ectomesenchyme forms the	Odontoblast. The dentin and dentin matrix are secreted by the odontoblasts. Cementum is by the inductive influence of radicular dentin on the cells of the dental follicle or dental sac.
The layer that is associated with enamel formation other than inner enamel formation in bell stage of odontogenesis is the	Stratum intermedium. This layer is closely associated with enamel formation which comes from the histological proof that it is absent in those part of tooth germ that out lines the tooth germ but does not form the enamel.
During the transition from bell to late bell stage of odontogenesis, expansion of stellate reticulum occurs by accumulation of	Accumulation of fluids
Stellate reticulum starts to collapse just before the	Enamel formation. It happens just before the enamel is formed. This event begins at the height of cusp or incisal edge. This reason for this is debated. Older view is that it occurs to reduce the distance between ameloblasts and the capillaries near the outer enamel epithelium, as the nutrients cannot diffuse the newly formed dentin and enamel. Now it is argued that the collapse is due to the continuous differential cell division adjacent to the areas of the cusp tip towards the outer enamel epithelium and is purely due to pushing nature of the cells.
The shape of outer enamel epithelium in bell stage of tooth development is	Low cuboidal. From the cuboidal shape in cap stage it flattens and forms folds on its outer surface during the enamel formation bringing the much needed nutritional supply closer to the ameloblasts, hence this functional adaptation.
Membrana preformitiva separates	Enamel organ and dental papilla. It is the basement membrane.
Membrana preformitiva appears	Prior to dentin formation
The organizing influence of the inner enamel epithelium on the surrounding ectomesenchyme is evident in the	Bell stage. It is seen as a cuboidal cell that latter turn in to a columnar form to produce the dentin.
Before the formation of the dental tissues the fibers of the dental sac are arranged in	Circular fashion, Just like a capsule
The acellular zone of dental papilla in bell stage of odontogenesis contains	Aperiodic fibrils. Though it is acellular few collagen like fibrils with out the periodic banding is observed in this otherwise empty space.
The epithelial remnants called the cell rests of Malassez are found in the	Periodontal ligament of erupted teeth
Cell rests of Malassez are the remnants of the	Hertwig’s epithelial root sheath
The shape of a crown is primarily determined by the	Cessation of mitotic division. In the bell stage, the differential cessation of the mitotic division of the inner enamel epithelial cells brings about the shape of a crown.
The number of blood capillaries in dental papilla increases during	Histodifferentiation. This occurs maximally at the initiation of crown stage of tooth formation.
Development of root formation begins after the enamel and dentin deposition reaches the	Future cementoenamel junction
Prior to root formation, the Hertwig’s epithelial root sheath forms the	Cervical loop. Just prior to the root formation a bend at the area where inner and outer enamel epithelium meets forms the epithelial diaphragm at the area of future cementoenamel junction.
If the continuity of the Hertwig’s epithelial root sheath is broken prior to dentin formation, a defect in the pulp wall occurs with no	Dentin and cementum. Often seen in pulpal floor of furcation and is the cause of accessory root canal formations. This defect is localized and often very small.
The proliferation of the cells of the epithelial diaphragm is accompanied by proliferation of the cells of the connective tissue of the	Pulp
Enamel pearls are sometimes found in	Furcation area of roots of permanent molars. This occurs when the cells of the Hertwig’s epithelial root sheath remain adherent to the radicular dentin and becomes active to produce the enamel.
The crown stage of tooth development begins with	Dentin deposition
As a result of lack of initiation the tooth that is most commonly missing is	Upper lateral incisor
Histodifferentiation succeeds the stage of	Proliferation
The process of histodifferentiation reaches highest in the	Bell stage
An important stage of morphodifferentiation in the crown, outlining the future             dentinoenamel junction is evident in	Advanced bell stage
Morphodifferentiation is impossible without	Proliferation
Disturbances in morphodifferentiation will not affect the	Function of ameloblasts. It may form supernumerary cusp or roots, twinning, loss of cusps or roots and malformed teeth.
Apposition is the physiologic process relating to the	Formation of enamel & dentin matrix
Which teeth of the permanent dentition have no deciduous predecessors?	Molars