Our mouth is made up of several complex components that work together to carry out some of the prime functions. Some of the critical purposes of the mouth include eating, drinking, swallowing, speaking, and tasting. Teeth are the essential aspects of the mouth that play a significant role in carrying out the functions mentioned above. Additionally, teeth help to provide a characteristic smile to a person.
Typically, human beings encounter two sets of teeth in life, namely the primary dentition and the permanent dentition. The permanent dentition erupts from the age of six years and lasts until the end of the lifetime. It is essential to understand the importance and functions of every dental tissue that makes up this unique asset of our mouth. Primarily teeth are made from pulp, dentin, and enamel. Each layer has its own characteristics.
Today’s article is dedicated to understanding the functions and structure of different tissues that build up a tooth. Moreover, we will also learn about different oral tissues in the mouth.
What are the teeth?
Human teeth are typically described as the part of the oral cavity that functions in mechanically breaking down the food by cutting, tearing, and crushing the food into smaller pieces. The permanent dentition consists of four types of teeth namely –
- Incisors – the front teeth that help in biting or cutting the food
- Canines – the cornerstones of the mouth help to tear the food into small parts
- Premolars – they crush the food and activate the digestive cycle (1)
- Molars – just like premolars, molars also aid in crushing and grinding the food into small particles
Tooth eruption is a process of tooth development that guides the tooth to move towards the oral cavity and break-free from the gums into the mouth. The first set of primary teeth usually erupt at the age of six months while the permanent dentition starts from the age of six years.
What are the different parts of a tooth?
Every tooth may differ in its structure and anatomy. However, a tooth typically consists of two main parts – the anatomical crown and root. The tooth crown is the part of the tooth that is exposed to the oral cavity and environment. The shape and size of the tooth crown may vary depending on the type of tooth.
The tooth root acts as an anchor that supports the tooth in the bony socket. Tooth root constitutes almost two-third of the tooth structure. Now that you’ve got an idea of the two main parts of the tooth let’s take a closer look at them –
The anatomic crown of the tooth is considered as the surface of the tooth that lies above the gum line. It is the only part of the tooth that is usually exposed to the oral environment. Moreover, the anatomic crown mainly contributes to providing a radiant smile. (2)
Typically, the anatomic crown is made up of three dental layers – the enamel, dentin, and the pulp tissue. All these three components play a crucial role in determining the shape, color, and strength of the tooth. Other functions of the tooth crown include –
- Aids in speaking
- Helps in chewing and swallowing of the food
- Gives a characteristic smile and dimension to the patient’s facial profile
The anatomic tooth root is usually found below the gum line. It is the part of the root that is embedded into the jaw bone. Typically, the tooth root is made up of pulp, dentin, and cementum. Some teeth like the molars and premolars may have multiple tooth roots for better anchorage and support in the jaw. (3) Tooth root constitutes the majority portion of the tooth which is around two-thirds of the total tooth structure. Every tooth root consists of a pulp canal which is popularly known as the root canal.
The tooth root stands firmly in the bony socket with the help of several tissue attachments called as the periodontal ligaments. All together the periodontal ligaments, the bony socket and he gingival tissue act as supportive periodontium that firmly holds the tooth in its ideal position and maintain its longevity.
What is the tooth made up of?
The tooth is made up of several essential layers of dental tissue that can be categorized as follows –
Enamel is popularly known as the hardest mineralized substance in the human body. It is one of the essential components of the tooth that forms the outermost protective layer of the tooth. The underlying dentin mostly supports enamel.
This highly mineralized layer of the tooth consists of around 96% of inorganic minerals, and the rest 4% is made up of water and organic materials. Permanent teeth usually have a characteristic color of the enamel which varies between light yellow to grayish-white. The color variation is due to the semi-translucency of the enamel, which may reflect the underlying dentin.
Enamel covers the anatomical crown of the tooth and extends between the cusp or incisal edge to the neck of the tooth. The neck of the tooth consists of the cementoenamel junction. (4) Primarily, the tooth enamel is made from minerals like hydroxyapatite. This accounts for the strength of the enamel. Enamel is the only mineralized layer in the mouth that does not contain collagen fibers. However, it is made from specialized enamel protein cells that lay down the mineralized layer. These proteins are referred to as ameloblasts.
Dentin is the second layer of the tooth that supports the enamel. In the tooth root, dentin acts as a support for the cemental layer. Typically, the cells that help to form the dentinal layer are termed as odontoblasts. This process is well known as dentinogenesis.
The dentin is usually characterized as a porous yellowish layer which consists of 70% inorganic components, 20% organic materials, and 10% water. The less mineral content makes this layer softer than the tooth enamel. This is one of the reasons why tooth decay progresses rapidly when it reaches the dentinal layer of the tooth. (5)
The dentin also surrounds the pulp chamber in the anatomic crown and pulp canals in the anatomic tooth root. One of the characteristic features of the dentinal layer is the presence of dentin tubules. These tubules are sensitive to air, pressure, and change in temperature. Often during enamel erosion, people suffer tooth sensitivity due to the exposure of dentin tubules to the oral environment.
Pulp forms the central most part of the tooth crown and root. It is the only living part of the tooth that is made by a complex network of nerves and blood vessels. Typically, the pulp determines the vitality of the tooth. Moreover, it provides all the nutritional content that helps in mineralization, repair, and strengthening of the tooth structure. (6)
The pulp also lines the odontoblasts which help in building the dentinal layer. Some of the standard pulp cells include fibroblasts, macrophages, and lymphocytes. Any disturbance in the tooth vitality is caused by the extension of the disease into the pulp tissue.
Tooth cementum is a specialized layer of the tooth that forms the outermost protective covering of the tooth root. Cementum is also considered as a bone like substance. As compared to the other dental tissues, cementum consists of about 45% inorganic components like hydroxyapatite crystals, 33% organic material like collagen fibers, and 22% water by weight.
The typical cells that help in forming this crucial layer of the tooth root are called as cementoblasts. Cementum is usually found to be thicker at the apex of the tooth root. The cementum is typically a yellowish layer that is softer than the dentin. Primarily it helps to support the tooth in the bony socket by providing attachment of periodontal fibers to the tooth root. (7)
A note on the supportive dental tissues
The supportive dental tissue is often referred to as the periodontium, which helps to provide better anchorage and support to the tooth in the mouth. Moreover, the periodontium allows sensations like touch and pressure, which may be felt while biting or chewing. Typically, the periodontium of the tooth consists of three main parts –
Gingival tissue or gums
Gums, clinically known as gingival tissue, are the soft oral tissues that cover the jaw bone and the neck of the tooth. Gums are crucial for the health of the teeth. They also demarcate the anatomic tooth crown from the anatomic tooth root. Typically, gingival tissue id made up of three epithelial layers, namely – the gingival, junctional and sulcular epithelium.
The gingival tissue further consists of two parts – the marginal gingiva that forms the gum line and the alveolar gingiva, which covers the underlying jaw bone. (8) The marginal gingiva often remains free and forms the gingival sulcus. Healthy gingiva is characterized by a coral pink color and an orange peel appearance.
The periodontal ligaments are one of the most essential components of tooth anchorage. These fibers are made from connective tissue and extend from the cemental layer of the tooth to the alveolar bone. Typically, periodontal ligaments only attach to the tooth root. Some of the prime functions of periodontal ligament include –
- Forms a direct link between the toot hand the bony socket
- Provides support and anchorage to the tooth
- Helps in resorption and formation of the bone during orthodontic tooth movement (9)
- Provides effective sensations of touch and pressure
- Aids in the eruption rate of the tooth
There are several networks of periodontal fibers that support the tooth in the bony socket. However, collagen fibers constitute the majority of the periodontal tissues.
The jaw bone is also referred to as the alveolar bone. This part of the periodontium typically forms the structural support around the tooth root. Alveolar bone undergoes continues modification throughout the life. The cells that help in bone modification include the osteoclast – bone-eating cells and osteoblasts – bone-forming cells. (10)
The alteration in the bone can be highly appreciated during orthodontic tooth movements. During the orthodontic treatment, an area of the bone experiences compressive force. This force activates the osteoclasts to resorb the bone and allow tooth movement in the desired direction. Similarly, a part of the bone experiences tensive forces by the stretching of periodontal fibers. This zone activates the osteoblasts to form the bony structure. Such unique functions are typical of the alveolar bone.
Overview of different dental tissues
By reading this article, it must be clear that the teeth are the most crucial aspect of our mouth. They not only help us to carry out some of the essential functions in our daily life but also provides a radiant smile. Everyone is aware of the types of teeth that make up the two sets of dentitions. However, it is essential to understand the functions of the dental tissues as well.
Typically, a tooth is made from three distinct tissues, namely the pulp, dentin, and enamel. The primary purpose of all these layers is to provide adequate protection and support for the tooth to last for a lifetime.
Some of the secondary oral tissues that act as an adjunct in the proper functioning of the mouth include the periodontal ligaments, gums, and the jaw bone. Together these tissues constitute the periodontium of the tooth. This article is specifically written to provide you vivid information about your teeth and its structural development.