In a dental context, occlusion refers to the relationship between the upper, maxillary, and lower, mandibular, teeth as they approach each other, both during rest and chewing.

Malocclusion is the misalignment of both the teeth and the jaws, and can cause a number of dental problems as well as health problems.  The misalignment of the teeth and jaws can be associated with a number of problems which include, crooked teeth, TMJ, gum problems and jaw muscle problems, too. 

When malocclusion occurs, the teeth, fillings, or crowns may wear, break or loosen.  It can also cause  teeth to be tender or ache, and can cause the gums to recede, as well. 

When the jaw is not aligned, muscles in the jaw may have to compensate and work harder, and this in turn can lead to muscle spasms, headaches or migraines, eye or sinus pain, and even pain in the neck, back and shoulders.  Research has shown that malocclusion is a contributing factor to breathing problems while sleeping, problems which include snoring, upper airway resistance syndrome and sleep apnea.

If an individual suffers from malocclusion, a visit to a dental professional is necessary to determine the correct treatment for his specific  problem.  Treatment for different alignment problems include tooth adjustments, replacement of teeth, dental splints to protect the teeth, relaxation therapy for teeth clenching, and removable dental appliances to alter the development of the jaw. 

In some cases, braces or other fixed dental appliances will be used to move the teeth into their correct position, and in extreme cases, jaw surgery may be required to correct malocclusion.