Occlusion in dentistry refers to the precise manner in which your upper and lower teeth meet when your mouth closes. This relationship is a complex, functional system that governs nearly all oral movements. A proper bite is foundational to overall oral health, directly influencing your ability to chew food efficiently, speak clearly, and maintain the stability of your teeth and jaw joints. When the upper and lower dental arches align correctly, the forces generated during biting are distributed harmoniously, protecting the entire system from excessive strain.
Defining Dental Occlusion
Dental occlusion describes the contact between the teeth, categorized into two main types based on movement. Static occlusion refers to the contact points when the jaw is closed and stationary, with the teeth locked into their tightest fit. This position is technically known as maximum intercuspation (MIP), which represents the most number of tooth-to-tooth contacts possible.
Dynamic occlusion describes the sliding and gliding contacts that occur when the jaw is moving during functions like chewing, swallowing, and speaking. Dentists also consider centric relation (CR), which is a specific, repeatable position of the jaw joint (condyles) within the skull, independent of tooth contact. Ideally, the MIP should align closely with the CR position to ensure optimal function and stability for the teeth and the temporomandibular joints.
Classifying Normal and Abnormal Alignment
The standardized system for classifying the bite relationship was developed by Edward H. Angle, based primarily on the alignment of the first permanent molars. Normal occlusion, or Class I, is the ideal arrangement where the upper teeth slightly overlap the lower teeth, and the cusps of the upper molars fit precisely into the grooves of the lower molars. Class I can still include minor alignment irregularities like crowding, rotations, or cross-bites.
Any deviation from this normal arrangement is termed a malocclusion. Class II malocclusion, often described as an overbite, occurs when the upper jaw and teeth protrude forward relative to the lower jaw. This is characterized by the lower first molar being positioned too far back, creating a convex facial profile.
Class III malocclusion, or an underbite, occurs when the lower jaw extends too far forward, causing the lower front teeth to rest in front of the upper teeth. Here, the lower first molar is positioned too far forward relative to the upper molar, often resulting in a concave facial profile. These classifications help dentists diagnose whether the problem is purely dental or skeletal, involving the underlying jaw bones.
Consequences of Improper Occlusion
When the upper and lower teeth do not meet correctly, the resulting forces negatively affect the entire oral system. An unbalanced bite can result in excessive tooth wear, known as attrition, where uneven contact rapidly grinds down the enamel. This uneven force distribution can also cause teeth or existing dental restorations, such as crowns and large fillings, to crack or fracture over time.
Improper occlusion places excessive strain on the muscles responsible for chewing, leading to myofascial pain in the face, head, and neck. This muscle tension often manifests as frequent headaches, facial discomfort, or tenderness when chewing. A disharmonious bite is also a factor in the development of temporomandibular joint (TMJ) disorders. The unbalanced forces transmit stress directly to the jaw joints, potentially causing joint pain, clicking or popping sounds, and restricted jaw movement.
Methods for Correcting Occlusal Issues
Restoring occlusal balance involves an approach tailored to the specific nature of the malocclusion.
Occlusal Adjustment
For minor discrepancies, a dentist may perform occlusal adjustment or selective grinding. This involves the precise reshaping of the enamel surfaces to eliminate premature contact points. The goal is to ensure forces are distributed evenly across the dental arches.
Restorative Dentistry
More structural issues may require restorative dentistry to build up or alter the shape of teeth. Crowns or onlays can be used to restore worn-down teeth or change the height and contours of biting surfaces. This effectively repositions the jaw into a more harmonious bite.
Orthodontic Treatment
When the teeth are significantly misaligned, orthodontic treatment is necessary to physically reposition them. Braces or clear aligners move the teeth into their correct anatomical locations. This creates the ideal Class I relationship to ensure stability and function.