Understanding Tooth Structure
Isn't it interesting that often when we see old ruins, the arch structures remain standing?
These arches are stable because they distribute loads so well. They act as a compression dome.
The natural tooth can be likened to a compression dome, owing to its remarkable structural design and the way it efficiently distributes and absorbs forces during biting and chewing.
A compression dome is a structural element that is capable of supporting and dispersing compressive forces evenly across its surface. In the case of a tooth, the arrangement of its hard tissues, namely the enamel, dentin, and cementum, allows it to function as an effective compression dome.
The unique structure of the enamel and the dentin allows the stresses of function to be absorbed and dissipated in a way that minimises the risk of structural failure of the tooth itself. At the heart of this is the DEJ.
The dento-enamel junction (DEJ) is a distinct and intricate structure that serves as the interface between the dentin and enamel in a tooth. With particular properties, it is a critical region that contributes to the strength, integrity, and function of the entire tooth.
The DEJ possesses a unique wavy or scalloped pattern, which increases the surface area of contact between the dentin and enamel. This irregular boundary enhances the mechanical interlocking between the two tissues, improving their bonding strength. The scalloped nature of the DEJ also helps in distributing occlusal forces more evenly, reducing the risk of cracks or fractures.
As the enamel approaches the DEJ it decussates which increases its toughness and reduces crack propagation, meanwhile the mantle dentin extends collagen fibres across the DEJ which creates a fibre reinforced zone in this area. For this reason it is better to refer to the dento-enamel complex, or the DEC - a graded functional interphase at the heart of the tooth.
So here we have a natural structure - the tooth - which is designed to function as a unit to protect itself from functional stresses. Of course, as soon as we start to drill into it, it becomes compromised, much like removing the keystone from an arch - it will start to break down.