Head and Neck Anatomy Lecture #1: Dentition PDF

Head and Neck Anatomy Lecture # 1 Dentition  Introduction The dental technician and denturist must know the names, location, function and relationships of the various teeth in the human dentition. The tooth numbering systems are fundamental to the dental practitioner. Tooth eruption, dates and seq...

Head and Neck Anatomy Lecture # 1 Dentition  Introduction The dental technician and denturist must know the names, location, function and relationships of the various teeth in the human dentition. The tooth numbering systems are fundamental to the dental practitioner. Tooth eruption, dates and sequences form a basis for understanding growth and development of the human dentition. The Dentitions Humans have two sets of teeth or two dentitions: the primary and permanent dentition dentition=general arrangement of teeth The dentition is divided into the maxillary or upper arch and mandibular or lower arch Dentitions  Humans have three dentition periods: primary, mixed and permanent  The primary dentition consists of 20 primary or deciduous (baby) teeth  The permanent dentition consists of 32 permanent or adult (secondary) teeth  The permanent teeth that replace the primary teeth are called succedaneous teeth  The mixed dentition period takes place between ages 6 – 12 years when teeth of both dentitions is present in the mouth Primary Dentition (deciduous / baby teeth)  Children are born edentulous (no erupted teeth)  Dentition begins with the eruption of the first tooth at approx 6 months of age  all 20 primary teeth have erupted by 3 years of age  Only primary teeth are present in the mouth during the primary dentition period  Primary Dentition Consists of 20 teeth These teeth are shed and then replaced by the permanent dentition This process of shedding the primary teeth is known as exfoliation Each arch contains four incisors, two canines and four molars There are no premolars in the primary dentition Mixed dentition  This transitional stage is marked by the presence of both primary and permanent teeth  Occurs between approximately 6 and 12 years of age  The mixed dentition begins with the eruption of the mandibular first permanent molar and ends with the shedding or exfoliation of the last primary tooth  During this time there is significant growth of the jaws to accommodate the larger and more numerous permanent teeth The Permanent Dentition  The permanent dentition is the final or adult dentition and consists of 32 teeth  This period begins at approximately age 12 when the last primary tooth is shed  The permanent dentition is completed with the eruption of the third molars around age 18 – 25 years  Each arch contains 4 incisors, 2 canines, 4 premolars, and 6 molars  The Dental Arches  There are two dental arches: the maxillary arch (upper) is actually part of the skull and is fixed and not capable of movement  The roots of the maxillary teeth are anchored in the maxillary bone  The mandibular arch (lower) is capable of movement through the action of the temporomandibular joint  The mandible is the bone that anchors the roots of the lower teeth thus the name mandibular arch  When the teeth of the maxillary and mandibular arches are in contact, the teeth are in occlusion  The midline divides the arches into right and left Quadrants When the maxillary and mandibular arches are each 1 2 divided in the midline, there are four sections called quadrants Each quadrant of permanent dentition contains eight permanent teeth and a quadrant of primary dentition contains five primary teeth 4 3  R L FDI Primary 55 5 6 65 Teeth 54 63 64 53 52 51 61 62 71 72 73 82 81 83 74 84 75 85 8 7 Sextants Sometimes it is necessary to divide the dentition into 6 parts; each part is identified as a sextant Maxillary right posterior Maxillary anterior Maxillary left posterior Mandibular right posterior Mandibular anterior Mandibular left posterior Eruption of teeth  Permanent teeth that replace or succeed the primary dentition are called succedaneous teeth  The permanent molars are non succedaneous teeth as they do not succeed or replace any deciduous teeth  The permanent premolars replace the primary molars  There are 12 non succedaneous teeth in the permanent dentition – Primary which teeth are these? teeth  Anterior Teeth The anterior teeth are the central and lateral incisors and the canines These teeth are aligned to form a smooth, curving arc from the distal (back) of the canine on one side of the arch to the distal (back) of the canine on the opposite side Posterior Teeth The posterior teeth are the first and second premolars and the first, second and third molars The posterior teeth are aligned with little or no curvature and appear to be in an almost straight line Types of Teeth in the Primary Dentition The primary dentition contains central and lateral incisors, canines and first and second molars There are no premolars in the primary dentition Naming and coding of teeth  Used as a means of identifying teeth for charting and descriptive purposes  Fundamental for dental hygiene practice  When identifying a specific tooth list the dentition, arch, quadrant and tooth name (in that order) eg permanent mandibular right canine  Three basic tooth numbering systems (nomenclature): 1. Universal / National System 2. International Standards Organization System (ISO) also known as the Federation Dentaire International System (FDI) *used at GBC* 3. Palmer Notation System  Universal/National Numbering System: Permanent Teeth Approved by the American Dental Association in 1968 and primarily used in the United States The permanent teeth are numbered from 1 to 32. Numbering begins with the upper right third molar, works around to the upper left third molar, drops to the lower left third molar, and works around to the lower right third molar. Universal/National Numbering System: Primary Teeth The primary teeth are lettered with capital letters from A to T Lettering begins with the upper- right second primary molar (tooth A) works around to the upper left second primary molar (tooth J), drops to the lower left second primary molar (tooth K) and works around to the lower right second primary molar (tooth T) Dental Chart using Universal Tooth Notation Palmer Notation System In this system each of the four quadrants is assigned a ‘bracket’ made up of a vertical line and a horizontal line which looks like Numbers 1 – 8 are inserted within the bracket for permanent teeth and letters A - E inserted for primary teeth Maxillary right Maxillary left Mandibular right Mandibular left Palmer Notation System Palmer Notation System Examples of Palmer notation system: 4 Permanent maxillary right first premolar E Primary mandibular left second molar 6 Permanent mandibular right first molar FederationDentaire Internationale (FDI) Numbering System In the FDI system each tooth is given a two digit number No letters or single digit numbers are used The first digit indicates the quadrant and the second indicates the tooth within the quadrant (1to 8 in permanent and 1 to 5 in primary) The second digit depends on the position the tooth occupies relative to the midline The lowest number is give to the tooth closest to the midline and counting back to the most posterior tooth in the arch The quadrants of permanent teeth are numbered as follows: Maxillary right quadrant is #1 Maxillary left quadrant is #2 Mandibular left quadrant is #3 Mandibular right quadrant is #4 R 1 2 L 1 4 3 FDI System The quadrants of the primary teeth are numbered as follows: Maxillary right quadrant is #5 Maxillary left quadrant is #6 R L Mandibular left quadrant is #7 5 6 Mandibular right quadrant is #8 8 7  18 R L 28 FDI 17 27 Permanent 16 26 Teeth 15 1 2 25 14 13 23 24 12 11 21 22 42 41 31 32 33 43 44 34 45 4 3 35 46 36 47 37 48 38  Which tooth is chipped? Which teeth are covered with gold crowns? Discover your own Dentition 1. Determine how many teeth you have. 2. If less than 32, determine which ones are missing? 3. Identify the missing teeth using FDI notation system.