Dental occlusion is the relation between the surfaces of the mandibular and maxillary teeth at rest and while in function. In other words, it is the contact between teeth. The term "occlusion" actually derives from the Latin proverb occludere. It means "to close up."

Every person has unique body characteristics. The face with its own individual set of teeth and jawbones gives a more aesthetical look to a person. The normal occlusion not only gives a more pleasing appearance but also provides an efficient mastication process and improves digestion.

During a lifetime, the occlusal relationship of a person can change multiple times. It is crucial to detect these changes to prevent their caused consequences and provide normal masticatory functions.

If a proper alignment is present, the teeth have strong contact with their neighbor and opposing teeth. Over the years, the spacing between teeth gradually changes, causing the teeth to become looser. It results in occlusal relationship changes. These changes are not only associated with age but also with various disorders.

In the maintenance of correct occlusion, more structures than just teeth are involved, and contacts between teeth cannot be looked at in isolation. The masticatory system also involves the periodontium, as well as skeletal components such as the temporomandibular joints and muscles of mastication.

In order to know if the dental treatment needs to be preventive or restorative, it is crucial to understand the basics of dental anatomy and physiology, especially dental relationships and occlusion.