The coronal part of a tooth, commonly called the crown, is the section visible in the mouth above the gumline. It is distinct from the root, which anchors the tooth within the jawbone. The transition between the crown and the root occurs at the dental neck, right at the gumline.
The term “coronal” refers to anything related to this crown portion. In a healthy mouth, the visible clinical crown and the anatomical crown—the part covered by enamel—are very similar in size.
The Layers of the Tooth Crown
The tooth crown is composed of three distinct layers. The outermost layer is the enamel, the hardest and most mineralized substance in the human body, consisting of approximately 96% inorganic material like hydroxyapatite crystals. This tough shell shields the inner parts of the tooth from chewing forces and exposure to different temperatures and chemicals.
Beneath the enamel lies the dentin, which forms the bulk of the tooth’s structure. Dentin is a hard, calcified tissue but is softer and more porous than the enamel. It contains microscopic tubules that connect to the tooth’s nerve center, which is why enamel wear can cause sensitivity as stimuli travel through these tubules.
At the center of the crown is the pulp chamber. This hollow area contains the dental pulp, a soft tissue composed of nerves, blood vessels, and connective tissue. The pulp keeps the tooth alive and responsive by providing it with nutrients and sensory feedback.
Functions of the Tooth Crown
The primary function of the crown is mastication, or chewing food. The shape of each crown is adapted for a particular task. For example, incisors at the front have sharp edges for cutting food, while canines have pointed cusps for tearing. Premolars and molars have broader, flatter surfaces with ridges and grooves for grinding and crushing food.
The tooth crown also plays a part in phonetics. The interaction between the tongue and the teeth is necessary to form many of the sounds required for clear speech. The crowns help control airflow from the lungs to produce distinct consonants and vowels.
The crowns also have an aesthetic function. As the visible portion of the teeth, their shape, color, and alignment are major components of a person’s smile. They also provide structural support for the lips and cheeks, contributing to the natural contours of the face.
Common Issues Affecting the Crown
One of the most frequent problems to affect the tooth crown is dental caries, commonly known as cavities. Caries occur when acids produced by bacteria in the mouth demineralize and break down the hard enamel. If this process continues, the decay can penetrate through the enamel and into the dentin, compromising the tooth’s structure and potentially leading to an infection of the pulp.
Physical damage is another common issue. Accidental impacts, biting down on hard objects, or chronic teeth grinding can cause the enamel to chip or fracture. The severity of these injuries can range from small, cosmetic chips to large breaks that expose the sensitive dentin or pulp chamber. Such fractures can weaken the entire tooth structure.
The crown can also be affected by gradual wear. This wear can be mechanical, caused by bruxism (teeth grinding), or chemical, resulting from erosion caused by frequent exposure to acids from foods, drinks, or stomach acid. This acidic erosion softens the enamel, making it more susceptible to being worn away.