Dental Anatomy

What aesthetic characteristics, beyond dental anatomy, bring harmony to the elements found in the mouth, leading us to perceive beauty? How can we tell if these structures are healthy and functioning perfectly?

From the complexity of the periodontium to the fantastic formation of the mineralized structures of teeth, we invite you to explore the oral structures and tissues that make up our teeth and gums. Immerse yourself in this educational journey and discover the world of Dental Anatomy.

The dental element

The mammalian tooth is an organ composed of different structures that perform specific functions. Macroscopically or morphologically, the tooth has: Crown, Root, and Pulp Chamber, which is a kind of tunnel that runs inside the tooth, and inside this tunnel is the Dental Pulp, a soft tissue containing cells and nourished by blood circulation.

The crown is the part that is visible – outside the gums – and is directly responsible for cutting and grinding food. The crown accounts for about 1/3 of the tooth's length.

The remaining 2/3 of the tooth's length is formed by the dental root, which is the part hidden inside the gums, responsible for supporting the tooth in the jaws and withstanding the chewing force. At the opposite end from the dental crown is the root apex, the very end of the root, in the deepest part, most hidden inside the jaws.

At this point, you'll find the Apical Foramen – a small opening – almost the width of a hair, through which an arteriole and a venule pass (which are very thin blood vessels for blood to enter and leave) responsible for nourishing the cells of the dental pulp, and finally a nerve fiber responsible for giving sensitivity to the teeth, the famous dental nerve.

Dental Anatomy – Groups of teeth according to function

Humans have 32 teeth, 16 in the upper arch (maxilla) and 16 in the lower arch (mandible). In each maxilla, we have four groups of teeth bilaterally: incisors, canines, premolars, and molars. These groups are morphologically divided according to function: incisors and canines cut food, and premolars and molars grind it.

Dental Anatomy – What tissues make up the teeth?

Now we will address this histologically – that is, we will analyze the tissues that make up each of these parts of dental anatomy: Dentin constitutes the root of the tooth. Enamel covers and protects the dentin in the portion called the crown. The dental pulp is a non-mineralized tissue. We will describe each of them and present didactic drawings that differentiate them.

Enamel

1. Enamel: Enamel is the outermost layer of the tooth and has the appearance of a thin white or translucent layer. It is the hardest substance in the human body and its main function is to protect the underlying dentin. Enamel is composed mainly of minerals such as hydroxyapatite and does not contain living cells. Its crystalline structure allows it to withstand chewing forces and protect the tooth against wear caused by chewing and exposure to acidic substances.

It is one of the wonders of creation. The enamel-forming organ, which builds the enamel throughout the embryonic period, is a delicate, almost gelatinous tissue. This tissue, called the enamel organ, is capable of forming one of the hardest structures in nature. This enamel organ covers the crown of the tooth throughout the tooth formation period. Upon eruption into the mouth, the enamel organ ends its formative role and disappears, transforming into junctional epithelium, a delicate tissue responsible for "gluing" the gum to the tooth, which surrounds the tooth forming the gum-tooth junction.

The main substance present in tooth enamel is a mineral called hydroxyapatite, which is a crystalline form of calcium phosphate. Hydroxyapatite represents approximately 96% of the composition of tooth enamel.

In addition to hydroxyapatite, enamel also contains small amounts of other minerals, such as fluoride, carbonate, magnesium, and sodium. These minerals help strengthen the enamel and resist demineralization caused by acids and bacteria.

Other components of tooth enamel include water (approximately 3-4%), proteins (mainly collagen), lipids (fats), and traces of metallic ions such as zinc and copper.

Dentin

2. Dentin: Dentin is a layer of hard tissue located just below the enamel. It constitutes the root – the entire root of the tooth – and the part of the crown below the enamel. Dentin is more yellowish and less hard than enamel, but still very resistant. Despite being highly mineralized, it has collagen fibers surrounded by a calcified matrix. These collagen fibers give dentin a certain capacity for deflection, allowing it to withstand masticatory forces. Furthermore, dentin is formed by microscopic tubules containing extensions of specialized cells called odontoblasts. These odontoblasts produce dentin throughout the life of the tooth, helping to keep it nourished and protected. Dentin also has greater sensitivity than enamel, since the dentinal tubules can transmit external stimuli to the dental pulp, such as temperature and pressure.

Dentin is composed primarily of hydroxyapatite, which is a calcium phosphate mineral. However, dentin contains a smaller proportion of hydroxyapatite compared to enamel. Hydroxyapatite constitutes approximately 70% of dentin, while the remainder consists of water (20%) and organic substances (10%).

Thus, the organic substances present in dentin include collagen, a fibrous protein that provides strength and flexibility to the dentin tissue. Collagen forms a matrix that interacts with hydroxyapatite to provide the structure and stability necessary for dentin.

Dental Pulp – commonly known as the Dental Nerve.

3. Dental Pulp: The dental pulp is the innermost part of the tooth, located inside the pulp chamber. It consists of soft tissue containing nerves, blood vessels, and cells that play a vital role in nourishing the tooth during its formation and development. The dental pulp is also responsible for the tooth's sensitivity, transmitting sensory information to the central nervous system. Therefore, the dental pulp has an immunological, or protective, function; this allows the pulp to work to protect the tooth against infections resulting from cavities that may invade the tooth canal.

The pulp chambers, or canals of the teeth, have infinite possibilities in terms of shape and anatomical variations. The number of roots, which can be 1, 2, 3, 4 or more in rare situations, means that some teeth represent a challenge for professionals dedicated to treating their root canals.

Examine the educational drawings, differentiating the dental structures:

But teeth don't just float around in the air, do they?

Dental Anatomy

Let's explore the components that hold our teeth in place to work. Let's talk about the "Periodontium"!

The periodontium is like a hug around the root of the teeth, nourishing and supporting it. Imagine it as a team made up of the gingiva, bone, root cementum, and periodontal ligament, all working together to protect and support the teeth.

Classification according to Function

The members of this team come together with the goal of doing two things:

1. Connecting the teeth to the bone and withstanding the forces of chewing – the periodontium supports and distributes the forces that occur when we chew, speak, and swallow. That is why we call it the supporting periodontium.

2. Protects against infections: The covering periodontium hides and protects the supporting periodontium of the teeth. It prevents microorganisms from invading and destroying the tooth's support structure. It is the gum proper, the part of the masticatory oral mucosa that lines the alveolar processes. That is why we call it the protective periodontium.

Classification According to Coating Type

Think of the mouth as a living surface that has three types of "skin":

1. Lining mucosa: covers the inside of the mouth, the cheeks (buccal mucosa), the inner part of the lips, the underside of the tongue, and the moist, loose skin under the tongue, in the region called the floor of the tongue. This lining mucosa is not part of the periodontium.

2. Specialized mucosa: Located on the surface, mainly in the posterior part of the tongue, represented by the taste buds – this is the group that does the most enjoyable work – tasting food! Obviously, it is also not part of the periodontium.

3. Masticatory mucosa: This is the "skin" that makes up the gums, the true guardian of the tooth support system. It is the protective periodontium. But we cannot forget that the palate, or roof of the mouth, is also covered with masticatory mucosa. This entire area contains keratin – a layer of skin made to resist friction.

Surface Anatomy of the Gingiva

The gingiva is the protective periodontium. It covers the alveolar bone in two bands: the free marginal gingiva (FMG) and the attached gingiva, which is firm and adhered to the bone.

The Free Marginal Gingiva It's the band that runs along the edges of the teeth, the 2 to 3 millimeters closest to the teeth. The gingival papillae are the small triangles between the teeth and give the gingival labium a beautiful "V" shape in the space between each tooth.

Attached gingiva This gingiva is characterized by its immobility and firm adherence to underlying tissues, including the periosteum and cementum. Visibly, it presents a speckled appearance similar to orange peel due to the epithelial ridges visualized in histological examinations.

The width of this gum tissue varies considerably, generally between 1 and 9 millimeters, depending on the region of the dental arch. The upper incisors commonly exhibit the greatest width, while the lower premolars have a narrower width. Furthermore, genetic factors and age influence this variation in gum tissue width due to tooth wear and the gradual extrusion of teeth over time.

Marginal groove or marginal groove – is a line formed by the meeting of the marginal gingiva and the attached gingiva. It is present only on the vestibular side. It corresponds in height to the bottom of the sulcus.

Dental Anatomy

What causes the gums to "stick" to the surface of the tooth?

Here, there is an important component called the "Junctional Epithelium," responsible for making the gum "stick" to the tooth surface. Therefore, it is responsible for making the gum adhere and seal this contact, preventing bacteria from penetrating between the tooth and the gum.

The attached gingiva tends to expand its width as we age due to the gradual traction force exerted by the gingival collagen fibers upon it. In terms of thickness, it is thinner on the buccal side and thicker on the lingual side.

Remember that it's important to keep the gingival margin clean, even if some areas are difficult to reach. The keratinization of the gums helps with cleaning, but it's not the main shield against disease. The best way to brush is... Bass Brushing Technique.

Finally, the "mucogingival junction" is like a line that separates the attached gingiva from the lining mucosa that is continuous with the buccal mucosa.

Gingival Sulcus

The gingival sulcus is an imaginary space that exists between the enamel of the tooth and the free marginal gingiva. Normally, it is positioned completely over the visible part of the tooth, known as the crown. Under normal conditions, the depth of the sulcus varies from 2mm on the free surfaces of the teeth to 3mm on the surfaces near adjacent teeth. Its delimitation is defined by the lateral wall, which is the inner part of the free gingiva, the dental wall, and the junctional epithelium located at the base of the sulcus.

The inner wall of the gingival sulcus is lined by a type of tissue called non-keratinized stratified squamous epithelium. This arrangement occurs due to the natural process of desquamation and cell renewal, which aids in the elimination of debris through the positive pressure of the gingival fluid. This continuous process prevents the formation of a keratin layer inside the gingival sulcus.

Anatomy of the Col area

Attention! In these posterior teeth, from the premolars backward, there is a part called the "col". In the region of these teeth, the papilla that faces the cheek (vestibular side) is distant from the papilla that faces the tongue (lingual side) due to the size and shape of these teeth. Therefore, it is a concave surface located below the contact point between adjacent teeth. There is no keratin there, and it is difficult to access for cleaning.

(When you chew something fibrous that can pass between your teeth and get stuck between your back teeth, that's where the "col" is! That's where diseases can start and hide. It's the team's weak point.)

Dental Anatomy – Conclusion

In the Article “"How is your gum health?"” We've expanded on this topic quite a bit. It's worth reading the article.

Understanding dental and periodontal anatomy, the role of each structure, and its natural characteristics helps us recognize when something is out of place or abnormal. Observe these details and think about them. Consider whether it's time to see a dentist.

Author: Nivaldo Pinho Gonçalves, Periodontist CROSC 9696

Reference: SOBOTTA, Johannes. ATLAS OF HUMAN ANATOMY HEAD, NECK AND NEUROANATOMY. 24 3 v. Guanabara Koogan, 2019.,