Dental occlusion, or the study of how teeth come into contact, is foundational to dental practice. Occlusion involves the relationship between the teeth, supporting structures, and the masticatory system. For dental professionals, understanding occlusion—both static and dynamic—is essential for successful treatment planning and patient comfort.

What is Dental Occlusion?

Dental occlusion refers to the way teeth align and interact during both static (stationary) and dynamic (moving) states of the mandible. Proper occlusion maintains a healthy balance between the teeth, periodontium, and temporomandibular joint (TMJ).

Static Occlusion

In static occlusion, the mandible is stationary, and there are specific terms to understand:

• Centric Occlusion (CO): Also known as Intercuspation Position (ICP), this is the maximum contact position between the upper and lower teeth. It’s the "bite" patients make when asked to close their teeth naturally.
• Retruded Jaw Position (RP): A guided jaw position, not the natural centric relation, often used for recording jaw alignment.
• Centric Relation (CR): This describes the position of the mandible relative to the maxilla with the jaw muscles relaxed. Unlike CO, it is independent of teeth and consistent whether or not teeth are present.
• Postural Jaw Position (PJP): The relaxed, upright jaw position when a patient is sitting or standing.
• Occlusal Vertical Dimension (OVD): This is the distance between the jaws when teeth are in ICP. It is crucial in determining facial aesthetics and treatment planning.
• Freeway Space: The natural space between the upper and lower teeth when the jaw is at rest, important for speech.

Dynamic Occlusion

Dynamic occlusion describes the contacts that occur when the mandible moves:

• Posterior Guidance: Includes several determinants, such as condylar angle, Bennett angle, and the curve of Spee. These anatomical aspects influence the mandible's motion.
• Anterior Guidance: Governed by the front teeth (incisors and canines) during mandibular movements, influencing overbite and overjet.

Dynamic occlusion involves both protrusive guidance, where contact occurs during forward jaw movements, and canine guidance, where the canines provide protection during lateral movements. Group function, on the other hand, involves shared contact among multiple teeth during these movements.

Common Occlusal Interferences

Occlusal interferences disrupt smooth jaw movement:

• Working Side Interference: Occurs on the side of the mouth moving laterally.
• Balancing Side Interference: Occurs on the opposite side of the jaw during lateral movements.
• Posterior and Centric Interference: When back teeth or specific tooth contacts disrupt occlusal balance during closure.

Ideal Occlusion

Ideal occlusion is defined at three levels:

1. Tooth Level: Includes multiple simultaneous contacts, no inclined contacts, and forces directed down the long axis of each tooth.
2. Articulatory System Level: Ensures the coincidence of ICP and CR, freedom in centric, and immediate posterior disclusion.
3. Patient Level: The ideal occlusion should be neuromuscularly tolerated by the patient and align with their current functional and comfort needs.

Conclusion

Understanding the principles of dental occlusion is essential for maintaining patient comfort, function, and aesthetics. For practitioners, a thorough knowledge of occlusion—including how to manage static and dynamic occlusal forces—ensures effective and lasting dental treatments.