Dental Anatomy Lecture PDF

Al-Noor University College /Dentistry Introduction to dental anatomy 1st Year Dental...

Al-Noor University College /Dentistry Introduction to dental anatomy 1st Year Dental Anatomy By: Assist. Lect. Alaa Hussein Ali 2023-2024  Introduction Dental anatomy is the science that studies the structure of the teeth and their correlated parts, it includes the surface form of the oral cavity, external and internal form of the individual tooth and their relationship to each other. Alaa H. Ali 2  Nomenclature Humans are Heterodont Which means that they have different-shaped teeth Humans are Diphyo dont Which means that they have two sets of teeth, the deciduous (primary) teeth and permanent teeth The word dentition refers to all teeth in upper jaw (maxilla) Alaa H. Ali and lower jaw (mandible) 3  Nomenclature Due to their location, the upper teeth are called maxillary teeth and together they form an arch shape called maxillary arch while the lower teeth are called the mandibular teeth together they form the mandibular arch of teeth. The maxilla is formed by two bones forming the upper jaw that is rigidly Alaa H. Ali attached to the skull The mandible horse- shoe shaped bone that articulates with the skull by temporo- mandibular joint (TMJ) 4  Types of dentition Humans have tow types of dentition throughout their life , one during the childhood and called the deciduous teeth and the other during most or all the adulthood and called the permanent teeth Alaa H. Ali 5  Primary dentition Primary or deciduous teeth begin to form prenatally at about 14 weeks in uterus and are completed postnatally at about 3 years of age. The first tooth in this dentition appears in the oral cavity at the age of 6 months and last emerge at about 28 weeks±4. The deciduous teeth remain intact ( barring loss from caries or trauma) till age of 6 years. Alaa H. Ali 6  Primary dentition The deciduous teeth have been called the milk teeth or baby teeth. These terms are improper because they foster the implication that they are useful for short period of time. It should be emphasized that they are needed for many years of growth and physical development. So premature loss must be avoided. Alaa H. Ali 7  Primary dentition There are 20 of deciduous teeth, 10 in each arch and 5 in each quadrant. Beginning from the median line, the deciduous teeth in each quadrant are named as follows: The central and lateral incisors (I) followed by the canines (C) then the molars (M) Alaa H. Ali 8  Formula for mammalian teeth The denomination and numbers of all mammalian teeth are expressed by formulae to differentiate the human dentition from those of other species. The denomination of each tooth is represented by the initial letter of its name ( I for the incisors, C for the canines, M for the molars) then followed by horizontal line and the number of each tooth type is placed above the line for the maxilla and bellow the line for the mandible. The formula represents one side only. Alaa H. Ali 2 1 2 I C M = 10 teeth on each side 2 1 2 9  Permanent dentition There are 32 of permanent teeth, 16 in each arch and 8 in each quadrant. Beginning from the median line, the deciduous teeth in each quadrant are named as follows: The central and lateral incisors (I) followed by the canines (C) then the premolars (P) and the molars (M). Synonyms of permanent teeth are the secondary teeth or succedaneuous teeth that succeed the primary teeth The first permanent tooth to erupt in the oral cavity is Alaa H. Ali first molar at age of 6 years and the last one to emerge is the third molar 18-25 years. The other teeth are presented at about 14-15 years. These teeth stayed lifetime if the maintained 10 properly.  Mixed dentition Starts when the first permanent teeth begin to emerge into the mouth. The emergence of these teeth begins the transition or mixed dentition period in which there is a mixture of deciduous and permanent teeth present. The transition period lasts from about 6 to 12 years of age and ends when all the deciduous teeth have been shed. At that time the permanent dentition period begins. Alaa H. Ali 11  Mixed dentition The transition from the primary dentition to the permanent dentition begins with the emergence of the first permanent molars, shedding of the deciduous incisors, and emergence of the permanent incisors. The mixed dentition period is often a difficult time for the young child because of habits, missing teeth, teeth of different colors and hues, crowding of the teeth, and Alaa H. Ali malposed teeth. 12  Permanent dental formula The number of permanent teeth in adult when third molar is presented is 32, 16 in each arch and 8 in each quadrant. So beginning from the median line, the permanent teeth are named as follows: The two front teeth central and lateral incisors (I) followed by one canine (C) then first and second premolars (P) and then first, second and third molars (M). Alaa H. Ali 2 1 2 3 I C P M = 16 teeth on each side 2 1 2 3 13  When comparing the formulae of primary and permanent teeth , we noted that differences are existed. In permanent formula, the 2 maxillary and 2 mandibular premolars are added and maxillary and mandibular third molars are added also. There is no premolars in primary dental formula and the primary molars are replaced by the permanent premolars Alaa H. Ali 14  The permanent first molar is often called 6-years molar, makes its appearance in the mouth before any of deciduous teeth are exfoliated. It comes just behind the deciduous second molars Alaa H. Ali 15 Thank you