Teeth are classified as incisors, canines, premolars (also called bicuspids), and molars. Humans usually have 20 primary (deciduous, "baby" or "milk") teeth and 32 permanent (adult) teeth. Additional roots are referred to as supernumerary roots. Maxillary molars usually have three roots. Maxillary first premolars and mandibular molars usually have two roots. Canines and most premolars, except for maxillary first premolars, usually have one root. As with the crown, dentin composes most of the root, which normally has pulp canals. The anatomic root is found below the CEJ and is covered with cementum. After eruption, it is almost always visible. The crown is within bone before eruption. Most of the crown is composed of dentin ("dentine" in British English) with the pulp chamber inside. The anatomic crown of a tooth is the area covered in enamel above the cementoenamel junction (CEJ) or "neck" of the tooth. This information serves a practical purpose for dentists, enabling them to easily identify and describe teeth and structures during treatment. Dental anatomy is also a taxonomic science as it is concerned with the naming of teeth and their structures. The development, appearance, and classification of teeth fall within its field of study, though dental occlusion, or contact between teeth, does not. Main article: Dental anatomy There are four main types of teeth in humans, shown labelled here.ĭental anatomy is a field of anatomy dedicated to the study of tooth structure. However, some babies are born with one or more visible teeth, known as neonatal teeth or "natal teeth". Primary teeth typically start to appear (" erupt") around six months of age and this may be distracting and/or painful for the infant. The first set, deciduous teeth, also called "primary teeth", "baby teeth", or "milk teeth", normally eventually contains 20 teeth. Humans, like most other mammals, are diphyodont, meaning that they develop two sets of teeth. Teeth are made of multiple tissues of varying density and hardness. The roots of teeth are embedded in the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums.
The incisors cut the food, the canines tear the food and the molars and premolars crush the food. Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. As such, they are considered part of the human digestive system. Human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting.
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