Human dentition

Its a ppt for get the basic idea about human dentition

1. HUMAN DENTITION HUMAN DENTITION PAPER- IVB

2. Dentition means- Arrangement of teeth in the dental arch. B . Types of teeth present in the dental arch. C . Characteristics of teeth. D . Total number of teeth present in the upper and lower jaw. E . Dental formula. F . Structure of teeth. WHAT IS HUMAN DENTITION?

3. GENERAL CHARACTERISTICS- Human teeth are characterised by the following features- 1 . THECODONT- Socketed teeth, that teeth are articulated with their root in to the dental sockets present in the dental arch. 2. DIPHYODONT- It means two set of teeth- a. Milk set of teeth or Deciduous teeth- Present at childhood. b. Permanent teeth- Milk set of teeth is replaced by permanent set of teeth; these set teeth are present beyond childhood. 3. HETERODONT- Different types of teeth having different morphological structure and functions. For example- In the milk set there are three types of teeth, namely incisor, canine and molar. In the permanent set of teeth there are four types of teeth. Eg .- incisor, canine, premolar & molar.

4. DIFFERENT TYPES OF TEETH ACCORDING THEIR SHAPE AND FUNCTION In the following way major structural feature and function of each type of teeth may be presented: INCISOR( I )- Anterior in position; crown is chiseled and with more or less straight, flat and sharp. These type of teeth have single root. Function- cutting. CANINE( C )- Antero lateral in position in the dental arch; crown is quite conical in shape. Such tooth is with a single root. Function- tearing PRE MOLAR( PM )- Such type of teeth are located behind the canine in the dental arch. These types of teeth are usually bicuspid and these are absent in the milk set but present in the permanent set. Usually single root but in rare case upper premolars have two roots. Function- Crushing and partly chewing.

5. Continued… MOLAR( M )- Lateral in position, crown is square like shape. There may be three or four cusps. These types of teeth usually have two or three roots. Functions- Grinding and crushing

6. STRUCTURE OF HUMAN TEETH In general human teeth consists of three main parts- CROWN- Projected in the oral cavity and covered with enamel, the hardest material in the human body. ROOT- Articulated into the socket present in the jaw. NECK- A short, constricted part in between the crown and root.

7. The following diagram shows the arrangement of different types of teeth in the dental arch.

8. Continued… From the diagram dental formula in case of Deciduous teeth is- Incisors(I)2/2 Canines(C)1/1 Molars(M)2/2 Total number of Deciduous teeth- Among  deciduous (primary) teeth , ten are found in the maxilla (upper jaw) and ten in the mandible (lower jaw), for a total of 20 . In case of permanent teeth dental formula is- Incisors(I)2/2 Canines(C)1/1 Pre-Molars(PM)2/2 Molars(M)3/3. Total number of Permanent teeth- Among  permanent teeth , 16 are found in the maxilla and 16 in the mandible, for a total of 32.

9. Dental tissues- A . Enamel- The protective outer surface of the anatomic crown. It is 96% mineral and is the hardest tissue in the body. B. Dentin - Located in both the crown and root, it makes up the bulk of the tooth beneath the enamel and cementum . It lines the pulp cavity. C. Cementum - This substance covers the surface of the anatomic root. D. Pulp- The central, innermost portion of the tooth. It has sensory, nutritive, and functions during the life of the tooth.

10. Abnormality in size Microdontia  is a condition where teeth are smaller than the usual size. Macrodontia  is where teeth are larger than the usual size. ABNORMALITIES- Abnormality in shape Fusion  is the union of two adjacent teeth during development. Concrescence  is the fusion of two separate teeth only in their cementum . Supernumerary roots  is the presence of a greater number of roots on a tooth than expected.

11. ANTHROPOLOGICAL SIGNIFICANCE OF TEETH Teeth seems to be a very important part in evolution, specially in primate evolution- a very important subject matter of anthropology. For many dental anthropologists, the core of the subject is tooth  morphology . Identification of different primate species is most readily done from tooth form in archaeological and fossil material. Among the higher primates as a whole, males tend to have larger teeth than females, particularly the canine teeth. Even modern humans show this to a small extent, and it helps to distinguish between the sexes in archaeological and forensic remains.

12. The cusps, ridges, and furrows that decorate the crown surface also vary within different species of primates. Thus teeth have great importance in anthropological studies, dentition also helps in personal identification and age estimation and also in sex identification . Continued…