The term “occlusal” refers to the chewing surfaces of the posterior teeth, which include the premolars and molars. These complex surfaces are designed for grinding and crushing food, a function fundamental to the digestive process. The concept of “occlusion” describes how the upper and lower teeth meet when the jaw closes. This relationship is central to dentistry, influencing efficient chewing and the stability of the jaw joint and surrounding muscles.
Understanding the Occlusal Surface
The occlusal surfaces of premolars and molars are not flat but feature an intricate landscape of anatomical structures. This surface is characterized by raised areas known as cusps, which are separated by a network of ridges, grooves, pits, and fissures. These structures all contribute to the mechanical breakdown of food.
Ridges are linear elevations, while grooves are linear depressions. Pits are small, pinpoint depressions often found at the junction of grooves, and fissures are sharp, deep crevices. This complex morphology is important for mastication. However, the deep pits and fissures are highly susceptible to decay because they are difficult to clean. This makes the occlusal surface a common site for dental sealants, which are protective coatings designed to fill these spaces and prevent bacterial retention.
Defining Occlusion and Bite Alignment
Occlusion describes how the teeth of the mandibular (lower) arch contact the teeth of the maxillary (upper) arch. An ideal occlusion means the teeth are aligned within each arch and fit together harmoniously, allowing for efficient function and balanced force distribution. Dentists use the Angle’s Class I molar relationship as a benchmark, where the mesiobuccal cusp of the upper first molar aligns with the groove of the lower first molar.
Occlusion is categorized into two types. Static occlusion describes contacts made when the jaw is completely closed and unmoving, typically assessed when the teeth mesh together best (intercuspal position). Dynamic occlusion studies the contacts the teeth make while the jaw is moving, such as during chewing or speaking. Ideal dynamic occlusion involves protective guidance movements, like canine guidance, which ensures only the front teeth touch during lateral movements. Any deviation from this optimal relationship is termed malocclusion.
Consequences of Misalignment
When the upper and lower teeth do not meet in a balanced way, the resulting malocclusion can lead to problems throughout the masticatory system. Poor bite alignment often causes excessive, uneven tooth wear, technically known as attrition, where tooth structure is lost due to tooth-on-tooth contact. This pathological wear can flatten the occlusal surfaces and is often accelerated by habits like bruxism (the excessive grinding or clenching of the teeth).
As the enamel wears away, the underlying dentin may become exposed, leading to increased tooth sensitivity to hot, cold, or sweet stimuli. The unbalanced forces can also lead to fractured teeth or the failure of dental restorations, such as fillings or crowns. Chronic clenching and grinding habits put excessive strain on the muscles of mastication, often resulting in muscle tenderness, headaches, and pain in the temporomandibular joints (TMJ). Malocclusion is a primary factor contributing to temporomandibular joint disorder (TMD), a condition characterized by jaw pain, clicking, and limited movement.
Common Occlusal Treatments and Therapies
Managing issues related to the occlusal surface and bite alignment involves various therapeutic approaches aimed at restoring balance and protecting the teeth. One intervention is occlusal adjustment, or equilibration, which involves minor reshaping of the teeth’s biting surfaces. This procedure aims to eliminate premature or heavy contact points that may be causing muscle tension or uneven wear, helping to achieve a more evenly distributed bite.
For patients experiencing symptoms of bruxism or TMD, occlusal splints, often referred to as night guards, are frequently prescribed. These custom-made, removable acrylic devices fit over the teeth to create a barrier, preventing direct tooth-on-tooth contact and protecting the teeth from the destructive forces of grinding and clenching. Specific types of splints are designed as orthotic devices to stabilize the jaw joint, allowing the muscles to relax and potentially reducing symptoms like jaw pain and headaches.
In cases of severe malocclusion, permanent restorative treatments are necessary to re-establish a correct bite relationship. Orthodontic treatment, using braces or clear aligners, moves the teeth into better alignment, correcting the underlying malocclusion. Additionally, crowns or bridges may be used to restore severely worn or damaged teeth, rebuilding the occlusal surface to a functional and stable height and contour.