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The Secret Connection of Teeth: Do you know how cementum connects teeth to alveolar bone?
When we talk about the health of teeth, we often overlook the importance of the roots, and cementum is an important component of the roots of teeth. Cementum is a special calcified substance that covers the roots of teeth. It plays a key role in the periodontal tissue, responsible for connecting the teeth to the alveolar bone and stabilizing the position of the teeth through the fixed periodontal ligament.
The cells of cementum are trapped cementoblasts, called cementocytes.
Structure of cementum
Cementum is primarily composed of cementum cells that grow within its small cavities, similar to the pattern observed in bone. There are also tiny tubes in these small cavities, but unlike those in bone, these tubes in cementum do not contain nerves and do not radiate outward. Instead, they extend toward the periodontal ligament to deliver nutrients.
In addition to providing stability, cementum also has an important function in repair. If the tooth is injured, non-trapped cementoblasts line the surface of the cementum, forming a new cementum layer. This repairing ability allows teeth to remain healthy despite damage.
The relationship between cementum and other parts of the tooth
There are several important interfaces between cementum and other tissues of the tooth. Among them, the junction between cementum and enamel is called the cementoenamel junction (CEJ). Different types of transition interfaces may be present, and variations may even vary from tooth to tooth.
The formation of cementum is secreted by cementoblasts, and during tooth development, the first layer of cementum is formed from cell-free exogenous fibrous cementum.
Bony junction in tooth
The mid-tooth cementous junction (DCJ) is the junction formed after cementum covers dentin. The characteristics of this area are not as obvious as the junction between enamel and dentin. Since cementum and dentin are of the same embryonic origin, the interface between the two is relatively smooth.
Types of cementum
Cementum can be divided into several categories based on whether it contains cementum cells and the source of collagen fibers. It mainly includes acellular fibrous cementum, acellular exogenous fibrous cementum, cellular endogenous fibrous cementum, and mixed stratified cementum showing both cellularity and acellularity. These different types of cementum exist in different forms in different parts of the teeth, affecting the function and health of the teeth.
Composition of cementum
The hardness of cementum is slightly lower than that of dentin. About 45% to 50% of its composition is inorganic substances, mainly hydroxyapatite, and the remainder is organic substances and water. This composition allows cementum to play an important role in holding teeth together, including its relatively high fluoride content, which helps fight tooth decay.
Development of cementum
The production of cementum is mainly secreted by cementoblasts, especially at the root apex, which is the thickest. During tooth development, the secretion of these cells shows a regular pattern, forming the so-called Salt increment line. These incremental lines reflect cycles of activity and rest, revealing the progression of cementum.
Clinical significance
In some orthodontic procedures, if too much pressure is applied, it may cause root resorption and affect the stability of the teeth. At the same time, as we age, cementum becomes increasingly exposed, causing tooth sensitivity and other oral problems. Excessive proliferation of cementum is a pathological phenomenon called hypercementosis.
Tooth regeneration and repair
It is worth noting that cementum is able to repair itself to some extent, but it cannot completely regenerate. This means that in the case of healthy teeth, cementum is not resorbed but is continuously replenished over time.
The study of cementum has a profound impact on the field of dentistry, especially in DNA research for identifying human remains, where teeth as an important source have received increasing attention.
Thinking questions
Regarding tooth structure and its health, what are your thoughts on the function of cementum and the role it plays in overall tooth health?
