Odontogenesis: Developmental Process of Human Teeth
By Alexandra Hoethke, iGlobe News Editor and GW YAWP Editor
This research article describes the stages of teeth development and how they affect the development of the human teeth structure.
Odontogenesis is the developmental process of teeth. Teeth undergo a specific developmental process that enables them to develop within the human gums fully. Within the general operation of odontogenesis are distinct developmental stages. The stages in which the teeth develop are initiation, bud, cap, bell, apposition, maturation, root formation, and eruption. (John Giunta, 1:33-3:49) Teeth development begins in the fetus stage of human development. During this stage, the tissue in the gums forms around the teeth. After this process, the teeth start to perpetuate through the gums. This stage occurs after birth. Consequently, the development of human teeth further advances as the human body grows and develops. (John Giunta, 0:04-0:32)
Odontogenesis is the specific formation of a certain amount of teeth. The strategy odontogenesis will vary depending on the size, shape, and location in which the teeth develop in the maxilla and mandible. The maxilla is the upper jaw. While the mandible is the lower jaw. Hundreds of genes conduct the formation of teeth. Those genes are conveyed by individual molecules that keep track of the interactions within the membranous cellular tissue, which shadows over the surface of the tissues. (John Giunta, 0:50-1:05)
Odontogenesis begins within the embryo. The stomodeum develops and appears within the third week of human development in the womb. This stage sparks the beginning of teeth development. Subsequent to the third week, the maxilla and mandible areas of the mouth begin to form. After the development of the mandible and maxilla areas, the epithelium and mesenchyme cells will interact with one other, causing a reaction within their cells. The epithelium is a membranous cellular tissue that caps available surfaces in the body and enables the execution of specific functions. Mesenchyme cells allow structures to connect through tissues, bone, cartilage, lymphatics, and blood. The interaction with the epithelium and mesenchyme cells will then pave the way for the development of the tooth. This interaction occurs within the midsagittal section of the embryo. The midsagittal section is located between the future mandible and the future tongue. (John Giunta, 1:05-1:32)
When the maxilla and mandible develop, the general lamina begins to evolve. The frontal area of the general lamina consists of an area specifically for the development of the primary tooth lamina. Behind the area of the primary teeth development, lies the successional lamina. The successional lamina is the outermost layer of cells that create buds on the side of the gums, which is closest to the tongue. The successional lamina is the area in which permeant teeth develop during the later years of human life. Following the successional lamina, lies the continuous general lamina and the permeant third molar bud. The continuous general lamina and the permeant third molar bud covers the areas in which teeth develop. (John Giunta, 1:05-1:32)
The first stage of teeth development is classified as the initiation stage. This stage of teeth development occurs between the sixth and seventh weeks of human development during the embryonic period. During this stage, the embryo’s primitive mouth consists of ectoderm which is located in the lines of the mouth. Ectoderm is the outermost germ layer of an embryo. This area within the embryo consists of specific structures and tissues such as the nervous system, ears, eyes, and the epidermis. Once the ectoderm formation is complete, it will enable oral epithelium to shape into a curved strand of tissue. This strand of tissue creates a base membrane for teeth development within the embryo. The base membrane then proceeds to separate into the oral epithelium and mesenchyme. The seventh week introduces the development of the dental lamina layer. The dental lamina layer is the area in which arches form for teeth development. (Dr. Ali Al-mulhim)
The second stage of teeth development is classified as the bud stage. This stage begins during the eighth week of prenatal development. The bud stage introduces the area in which the tooth bud develops. This stage prepares group cells in specific arrangements that will prepare the embryo for tooth development. When the dental lamina buds combine with the mesenchyme, tooth germ develop. During the bud stage, the amount of dental lamina and mesenchyme increases. (Dr. Ali Al-mulhim)
The third stage of tooth development is classified as the cap stage. This stage occurs during the ninth and the tenth week of prenatal development. During this stage of teeth development, the oral epithelium grows downward into the mesenchyme. This stage begins the process of histodifferentiation. Histodifferentiation is the differentiation of tissue from cells that join in an undifferentiated group. This stage introduces major development within the developmental process of human teeth. Three new embryological structures are created within the cap stage. The dental follicle, dental papilla, and the enamel organ are identified within the cap stage. They are all classified as one tooth germ. The dental follicle is a sac that withholds the odontogenic organ. This organ withholds the developmental process for the tooth. The dental papilla enables the development of dentin and the pulp in a tooth. The enamel organ is a cellular grouping that appears within specific sections of a tooth in its cap stage of development. (Dr. Ali Al-mulhim)
The fourth stage of tooth development is classified as the bell stage. This stage occurs between the eleventh and the twelfth weeks of prenatal development. This stage induces an increased amount of characteristics within the tooth. The processes that occur during this stage classify as, differentiation, proliferation, and morphogenesis. The differentiation process creates four cells that are vivid within the structure of the enamel organ and the dental organ. The four cells are classified as inner enamel epithelium, outer enamel epithelium, stellate reticulum, and stratum intermedium. (Dr. Ali Al-mulhim)
The inner enamel epithelium is a layer of cells constructed in an upright pattern. The cells are located at the rim of the dental papilla. The outer enamel epithelium is the area located above the developing tooth. (CJ ’98) This layer above the developing tooth is split into two separate layers. The first layer consists of amnioblast cells, and the second layer consists of cuboidal cells. A stellate reticulum is a group of cells that are located in the center of the dental/enable organ. The cells within the center of the dental/enable organ are surrounded by water. The stratum intermedium is a layer of a few cells within the inner enamel epithelium and the stellate reticulum. (Dr. Ali Al-mulhim)
Within the bell stage, simultaneously, the dental papilla produces two new types of cells within the development of the tooth, the outer cells, and the central cells. The outer cell produces the dentin discharge of cells. The outer cell is also called, odontoblasts. The central cells produce the primordium of the pulp, located in the center of a tooth. (Dr. Ali Al-mulhim)
The fifth stage is classified as the apposition stage. During this stage of teeth development, the enamel, dentin, and cementum discharge in layers. This stage provides initial development for the future calcification of teeth. (CJ ’98)
The sixth stage classifies as the maturation stage or the crown stage. During this stage, the calcification of the tooth is executed. The thick tissues in the enamel and dentin are produced during this stage. During the maturation stage, the ameloblasts deposits some parts of the enamel and transports it into a substance which can be used for the process of mineralization. During the mineralization process, minerals move by ameloblasts and classify as proteins. The proteins are then used to complete the process of mineralization. (Dr. Ali Al-mulhim)
Following the sixth stage of tooth development, the roots of the teeth beginning to develop within the mouth. Once the crown of the tooth is completely created and formed, the tooth then begins to form its structure. This process is called eruption. The created structure plays a primary role in the development of the tooth’s root. This structure is called, the cervical loop. The cervical loop is located in the enamel organ. The root of the tooth consists of dentin and cementum. (Dr. Ali Al-mulhim) When the dentin is forming between the enamel, the process called, dentinogenesis, is occurring. When the cementum is forming along the root area of the tooth, cement oblasts begins surrounding the root’s dentin. (CJ ’98)
With the formation of the root complete, the tooth is now able to erupt. Tooth eruption is the process in which the tooth fully enters the mouth. This process is when the tooth is visible and perpetrates through the mouth. In the beginning, the primary teeth erupt through the mouth. As the human body matures and develops, the permanent teeth take the place of the primary teeth.
After the eruption of the tooth, many developmental processes take place as the primary teeth begin to appear through the gums. The primary teeth consist of twenty teeth. The process in which the primary teeth erupt through the gums is classified as primary dentition. The formation of primary dentition occurs during the age of eight months to the age of six years old. The order in which the primary teeth erupt is the central incisor, lateral incisor, first molar, canine, second molar. (Dr. Ali Al-mulhim)
The central incisor further classifies as the maxillary central incisor. The maxillary central incisor is the human teeth that are located in the maxilla. The lateral incisor also classifies as the maxillary lateral incisors. The area in which the maxillary lateral incisors develop is located in the upper area of the mouth. The maxillary lateral incisor teeth are located laterally from the midline of the face to the central incisors of the mouth. The first molar further classifies as the maxillary first molar. This tooth is located laterally from the midline of the human face, to the maxillary second premolars, which is located in the mouth. The canine teeth play a significant role when humans eat food. The canine teeth enable humans to function accurately when eating and speaking. They are located between the premolar teeth and the incisors. The second molar further classifies as the mandibular second molar. This is the tooth is located further away from the midline of the human face. The mandibular second molar is closely located on either end of the human mouth. (Dr. Ali Al-mulhim)
As the permeant teeth begin to develop, the primary teeth undergo a removal process. This process involves the removal of dentin and cementum in the primary root of the tooth. This process can result in the primary tooth’s departure from the mouth. While the primary teeth are removed, the osteoblast differentiates the growth of new bone.
The permeant teeth consist of thirty-two teeth. These teeth are incisors, canines, premolars, and molars. Molars are flat, large teeth that are located in the inner back area of the human mouth. At the ages of eleven and twelve years, usually, the primary teeth are entirely removed. The age in which all the primary teeth are removed will vary depending on the human’s developmental process. When the primary teeth are entirely removed, the permeant teeth take their place and stay in the human’s mouth for the remainder of their life. The permeant teeth undergo the same eruption process that the primary teeth. Once all of the permeant teeth are developed within the human mouth, the third molars begin to grow. Third molars are also referred to as the wisdom teeth. These teeth tend to be extracted due to the pain and discomfort they cause. (Dr. Ali Al-mulhim)
The timing in which all of these processes occur will vary on the human’s genetics, and the time it takes for them to develop fully. Although the speed at which people develop differentiates from person to person, the developmental process of teeth within all human mouths is very similar.
Works Cited Page
Giunt, John. (2011, June 24). Tooth Development [Video file].
Dr. Mastoor Ali Al-mulhim. “Tooth Development.” June 20. 2011. Accessed October 19, 2018.
CJ ’98. “Biology of the Human Dentition II.” Accessed October 19, 2018.
Merriam-Webster Dictionary. 1828. Accessed October 19, 2018.