Human Dentition Introduction PDF

Dental Anatomy Includes: 1- Structures of the oral cavity. 2- Overview of the dentitions 3- The relationship of the teeth to each other. 1- Structures of the oral cavity. 1-Lips 2-Teeth 3-Gingiva 4-Cheek 5-Tongue 6-Floor of the mouth 7-Roof of the mouth  1- Lips Tw...

Dental Anatomy Includes: 1- Structures of the oral cavity. 2- Overview of the dentitions 3- The relationship of the teeth to each other. 1- Structures of the oral cavity. 1-Lips 2-Teeth 3-Gingiva 4-Cheek 5-Tongue 6-Floor of the mouth 7-Roof of the mouth  1- Lips Two Lips Upper Lip and Lower Lip. The Corner of the mouth where the two lips meet is called Commissure Two Grooves are distinguished around lips. *Nasolabial groove *Labiomental groove.  2- Teeth Teeth are arranged in upper and lower dental arches. The upper arch is called Maxilla The teeth in this arch are called upper or maxillary teeth The lower arch is called the Mandible The teeth in this arch are called lower or mandibular teeth. Midline divides each arch into two equal right and left halves. There are 4 Quadrants in the oral cavity. There are Four types of teeth : 1-Incisors: There are two incisors, central incisor and lateral incisor. 2- Canines: There is one canine in each quadrant. Incisors and canines are considered Anterior Teeth.  3-Premolars There are two in each quadrant. First and second premolars. 4-Molars: There are three in each quadrant. First, second and third molars. Premolars and molars are considered Posterior teeth  3- Gingiva It is the tissue surrounds the cervical part of teeth.  4- Cheeks Linea alba buccalis  5- Tongue The tongue is a broad flat organ composed of muscles and glands. It rests in the floor of the mouth. It is the principle organ of taste and is most important in speech,mastication and swallowing.  6- Floor of the mouth It is shiny and some large blood vessels may be seen near the surface. Beneath the tongue there are two bilateral bulges caused by the presence of large salivary glands.  7- Roof of the mouth Its anterior part is called hard palate. Its posterior part is called soft palate which ends by a small fleshy structure named uvula  FUNCTION OF TEETH 1- Mastication  Functions Of Teeth 1- Mastication: It is the most important function of the teeth. The teeth are designed to perform this function. Incisors Canine Premolars Molars Chisel like Wedge like At least two Multiple projections Cutting or Cutting and projections (cusps) incising tearing (cusps). Grinding Tearing and grinding 2- Appearance 2- Appearance: - Well arranged clean teeth with proper alignment give nice appearance to the face. – Teeth give support to the facial expressions. 3- Speech: Teeth are important for clear pronunciation and for production of sound. 4- Growth of jaws: The teeth play a role in the growth of the jaws in some periods of life.  The Dentitions Humans have two dentitions 1-The primary dentition ( Deciduous) (predecessors) 20 teeth. 10 maxillary and 10 mandibular. The dental formula is: 2 1 2 I --- C ---- M ---- = 10 2 1 2 2-The permanent dentition 32 teeth, 16 maxillary and 16 mandibular. The dental formula is : 2 1 2 3 I ---- C ---- PM --- M ---- = 16 2 1 2 3  Dentition periods 1-The primary dentition period: 6m to 6y (Pre-decessor, deciduous) 2 incisors, 1 canine and 2 molars. 2-The mixed dentition period: 6y to 12 y Ugly duckling stage: Different color & size Edentulous areas Inflammed gingiva  3-The permanent dentition period: after 12 y (secondary, adult or succedaneous ) 2 incisors, 1 canine, 2 premolars and 3 molars.  Note The permanent molars are not preceded with deciduous teeth so they may be termed as non- succedaneous teeth. Macro-anatomy of the Tooth Each tooth has three anatomical parts: I.Crown part of the tooth which is seen in the oral cavity and is called Clincal crown Part of the tooth covered by enamel is called Anatomical crown II.The Neck: cervical line Meating between crown and root (cemento- enamel junction) II.Root (s) part of the tooth embedded in the jaw bones and is called Clinical root Part of the tooth covered by cementum is called Anatomical root Clinlical crown may include all of the anatomical crown and part of the root.  Anatomical and clinical crown. Anatomical Clinical Crown Crown Part of the anatomical crown may be covered by gingiva. According to the number of roots teeth are classified into: 1- Single rooted teeth Incisors, canines, premolars except upper first premolar 2- Double rooted teeth Upper first premolar and lower molars 3- Triple rooted teeth Upper molars The undivided portion of the root is called root trunk MICRO-ANATOMY OF THE TOOTH Enamel: The enamel is the hardest tissue of the human body covering the crown of the tooth. Insensitive—no nerves Cannot be renewed. Dentine: Dentine is a cream colored hard material that makes up the bulk of the tooth. It is covered by enamel on the crown, and by cementum on the roots. Softer than enamel Does not have a nerve supply but it is sensitive Produced throughout life Cementum: The cementum is a thin calcified tissue covering of the roots. It meets the enamel at the neck of the tooth. Softer than enamel and dentin. Anchors the tooth to the alveolar bone along with the periodontal ligament Pulp: A soft tissue rich with blood vessels and nerves responsible for nourishing the tooth. The pulp in the crown of the tooth is known as the coronal pulp or pulp chamber. In the root it is called root canals which end with apical foramen. Typically sensitive to extreme thermal stimulation (hot or cold)  Microanatomy Pulp chamber Three calcified tissues: Enamel, Dentin and Cementum Root canal And one soft tissue, Pulp. Pulp cavity consists of : Pulp chamber and pulp canal or canals The Periodontium It is the investing and Supporting Attachment System of Teeth. It consists of: Two Soft Tissues: 1- Gingiva 2- periodontal ligament Two Hard Tissues: 1- cementum 2- alveolar bone  Tooth Numbering System 1) Palmer Notation System: The permanent teeth are numbered from 1-8 on each side from the midline. Upper right Upper left 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 Lower right Lower left 8 Upper right third molar 3 Upper left canine 5 Lower left second premolar 1 Lower right central incisor The deciduous teeth are lettered from A-E on each side from the midline. B Upper left deciduous lateral D Upper right first deciduous molar incisor Lower right second deciduous C Lower left deciduous canine E molar  1-Palmer Notation System Right For permanent teeth Left 1 1 2 3 1-8 3 2 8-1 4 4 5 5 6 6 7 7 8 8 8 7 6 8-1 5 1-8 4 3 1 2 Palmer Notation System A For primary teeth B C E-A D A-E E E-A A-E  2- The international numbering system (The two digit system) The teeth are designed by using two-digit systems: a. The first digit of the code is located at the left side of the number and indicates the quadrant. In the permanent dentition. In the deciduous dentition. U.R. 1 2 U.L. U.R. 5 6 U.L L.R. 4 3 L. L. L.R. 8 7 L.L. b. The second digit is located at the right side of the number and indicates the number of the tooth in the quadrant. ****The two digits should be pronounced separately. Permanent teeth 18 17 16 15 14 13 12 11 21 22 23 24 25 26 27 28 48 47 46 45 44 43 42 41 31 32 33 34 35 36 37 38 15 Upper right second premolar 33 Lower left canine Deciduous teeth 55 54 53 52 51 61 62 63 64 65 85 84 83 82 81 71 72 73 74 75 55 Upper right second deciduous 72 Lower left lateral deciduous molar incisor First Digit = quadrant 12 11 21 22 Second Digit = tooth 13 23 14 number 15 24 25 16 26 17 27 18 28 For permanent Teeth 38 48 1 2 47 37 36 46 45 35 4 3 44 43 34 33 42 41 31 32  51 61 First Digit = quadrant 52 62 53 63 Second Digit = tooth number 54 64 55 5 6 65 For Primary Teeth 8 7 85 75 5 6 84 8 7 74 83 73 82 81 71 72 3)The universal numbering system (American numbering system): The number is always preceded by the sign # to designate that the system is used for universal system. Permanent teeth (1 – 32) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 #28 Lower right first premolar #16 Upper left third molar  Deciduous teeth (1 – 20) The number is preceded by d # 1 2 3 4 5 6 7 8 9 10 20 19 18 17 16 15 14 13 12 11 Or (A - T) The letter is preceded by # only A B C D E F G H I J T S R Q P O N M L K d# 14 Lower left deciduous lateral incisor #B Upper right deciduous first molar  Universal system for Permanent Teeth UNIVERSAL SYSTEM FOR PRIMARY TEETH 3-Tooth Orientational Terms: Each Tooth Has Five Surfaces Like A Box With 4 Sides And A Roof.  LABIAL OR BUCCAL Towards the Towards the lip cheek FOR POSTERIOR TEETH ANTERIOR TEETH PALATAL OR LINGUAL towards the towards the palate tongue MESIAL towards OR DISTAL away from the midline the midline  MIDLINE M M D D  INCISAL OR OCCLUSAL For anterior teeth For posterior teeth To determine a specific area of the crown. Line and point angles Line Point angle angle Incisal Edge Line And Point Angles Of The Anterior Teeth Line And Point Angles Of The Posterior Teeth  Note Note: The anterior teeth have fewer line angles because the meeting of the mesial and distal surfaces with incisal ridge are rounded , so the mesio-incisal and disto-incisal line angles are practically not exist.. Lingo-mesial L. A. Lingo-distal L. A. Labio-mesial L. A. Labio-distal L. A. Lingo-mesial L. A. Lingo-distal L. A. Bucco-mesial L. A. Bucco-distal L. A.  Division into thirds Incisal &occlusal Lingual Buccal Middle Mesial Middle Distal Middle Cervical  Mesial Middle Distal Lingual Middle Buccal Cervical Middle Apical Distal half Mesial half Lingual half Buccal half  Anatomical landmarks Lobe. A - Crown Elevations Tubercle. Ridge.  Lobe. It is one of the primary centers of calcification and growth formed during the crown development. There are three, four or five lobes The pulp chamber has pulp horns corresponding to these lobes.  Mamelons Lobe Cingulum Cusps Cusp triangular ridge. Cusp slopes  1. MAMELONES: They are three small round projections of enamel present in the incisal third of newly erupted incisors. After normal use, eventually the mamelones wear down into a flat edge.  2.CINGULUM: It is the enlargement or bulge on the cervical third of lingual surface of the crown in anterior teeth.  3-CUSP: Elevation of various shape & size present on the occlusal surface of post. Teeth and incisal portion of canine. It is formed of enamel, dentin& pulp Tubercle. It is a small elevation. It is produced by excessive formation of enamel. Tubercle differs from cusp as it is formed of enamel only while cusp is formed of pulp horn covered by dentin and enamel.  Ridge. Definition: It is a linear elevation on the different surfaces of the crown. 1- Ridges can be found on the Facial surfaces: A- Labial (that exist in canines) or Buccal (that exist in premolars). B- Cervical: in all teeth at the C1/3 2- Ridges can be found on the Lingual surfaces: A- Lingual (that exist in canines). B- Marginal: in all anterior teeth. C- Incisal: in all anterior teeth. D- Cusp ridge: or cusp slope. 3- Ridges can be found on the Occlusal surfaces: A- Triangular (that exist in all posterior teeth). B- Marginal: in all posterior teeth. C- Transverse: in lower premolars. D- Oblique: in upper molars. Keep smile  B- Crown Depressions Linear depression Circumscribed depressions  Developmental grooves Denoting union of lobes Linear depression Supplemental grooves They do not denote union of lobes. Fissures Incomplete enamel union  Developmental grooves Denoting union of lobes Supplemental grooves 1- Linear depression They do not denote union of lobes. Fissures Incomplete enamel union Note SULCUS: It is a broad depression or valley on the occlusal surfaces of posterior teeth. Its inclines meet in a developmental groove and extend to the cusp tips.  Lingual fossa Fossa Mesial &distal fossa Central fossa Circumscribed depressions True Present in the bottom of central, mesial and distal triangular fossae Pits Faulty Usually develops as a result of incomplete formation of enamel.  Fossa Mesial &distal fossae Lingual fossa Central fossa  pit True pit Faulty pit Present in the bottom of Usually develops as a central, mesial and distal result of incomplete triangular fossae. formation of enamel. At the end of buccal groove SOCKET: It is the bony space in the alveolar bone containing the roots of erupted tooth. CRYPT: It is the bony space in the alveolar bone containing the developing unerupted tooth.