![]() The mandibular condyle and the squamous portion of the temporal bone, at the base of the cranium articulate with one another. The lower facial skeleton on the other hand, is formed of the mandible, a U shaped bone, which supports the lower teeth and also forms part of the TMJ. This forms the palate of the oral cavity and also supports the alveolar ridges that hold the upper teeth in place. Two irregularly shaped bones fuse at the intermaxillary suture during development forming the upper jaw. ![]() The maxilla forms a crucial aspect of the upper facial skeleton. The masticatory system is largely influenced by these intra and inter-arch relationships and a wider understanding of the anatomy can greatly benefit those who want to understand occlusion. The teeth are highly specialised and different teeth are involved in specific functions. This bundle of connective tissue fibres is vital in dissipating forces that are applied to the underlying bone during the contact of teeth in function. The periodontal ligament unites the cementum on the outside of the root and the alveolar bone. ![]() Teeth consist of two parts: the crown, which is visible in the mouth and lies above the gingival soft tissue and the roots, which are below the level of the gingiva and in the alveolar bone. The human dentition consists of 32 permanent teeth and these are distributed between the alveolar bone of the maxillary and mandibular arch. One cannot fully understand occlusion without an in depth understanding of the anatomy including that of the teeth, TMJ, musculature surrounding this and the skeletal components. (Institute of Dentistry, Aberdeen University) T = Maximum opening of the mandible combined rotation and translation of condylar heads. R = Mandibular opening with rotation of the condylar heads but without translation. ICP = Here we see the condyle position when teeth are in the intercuspal position. ![]() Like class II oclussion, to correct this malocclusion when it is skeletal, the indicated treatment is orthodontics combined with orthognathic surgery.Anatomy of the temporomandibular joint - RCP = Here we see the condyle when teeth are in the retruded contact position, a reproducible position. In patients with this malocclusion, the profile has a concave appearance, with a prominent chin.Ĭlass III problems are usually due to excessive growth in the lower jaw, a lack of upper jaw growth, or a combination of both. In adults, this malocclusion, when skeletal, requires orthodontic treatment combined with orthognathic surgery.Ĭlass III occlusion is when the lower molars are very forward and do not fit their corresponding upper molars. In this faulty relationship, the lower teeth and the jaw project more forward than the upper and maxillary teeth. In many cases, class II problems are inherited genetically and can be aggravated by environmental factors such as finger sucking. The profile of a patient with class II has a convex appearance, with a retracted chin and lower lip.Ĭlass II problems may be due to insufficient growth of the lower jaw, excessive growth of the upper jaw or a combination of both. In this malocclusion, the upper front and maxillary teeth project more forward than the lower teeth and the jaw. This is the correct occlusion, and it gives the person a well-balanced profile in the anteroposterior plane.Ĭlass II occlusion occurs when the lower dental arch is posterior (more towards the back of the mouth) than the upper one. Class IĬlass I is a normal relationship between teeth, jaw and jaw. In addition, patients with malocclusions have an imbalance in the facial features, which may be more or less noticeable. If left untreated, malocclusions can cause functional problems such as tooth wear, mastication and digestion problems, speech problems, jaw joint (TMJ) pain, sleep disorders and even sleep apnea. Therefore, if maxilla and jaw are not well aligned, we are before a malocclusion, and it is necessary to seek a treatment to align them. The position of the jaws is the bony base of the bite. This is important because the classification of the bite also indicates whether there is a skeletal discrepancy, and helps determine why the bite does not fit correctly. This classification refers to the position of the first molars and t he way in which the upper ones fit together with the lower ones. Classification of the bite (occlusion) is divided into three main categories: Class I, II and III.
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