Overview of the Dentitions PDF

OVERVIEW OF THE DENTITIONS CHAPTER 11 Copyright © 2021 by Elsevier, Inc. All rights reserved. 1  Dentition is the term used to describe the natural teeth in the...

OVERVIEW OF THE DENTITIONS CHAPTER 11 Copyright © 2021 by Elsevier, Inc. All rights reserved. 1  Dentition is the term used to describe the natural teeth in the jawbones INTRODUCTION The dental assistant must know the names, locations, and functions of the teeth The dental assistant must also understand the various systems of numbering the teeth Copyright © 2021 by Elsevier, Inc. All rights reserved. 2  Although there are only two sets of teeth, there are three dentition periods DENTITION Primary PERIODS Mixed Permanent Copyright © 2021 by Elsevier, Inc. All rights reserved. 3  The first set of 20 primary teeth is called the primary dentition PRIMARY This dentition is commonly DENTITION referred to as the “baby teeth” You may also hear the term deciduous dentition, an older and less frequently used dental term to describe the primary dentition Copyright © 2021 by Elsevier, Inc. All rights reserved. 4 FACIAL AND BUCCAL VIEW OF A PRIMARY DENTITION Copyright © 2021 by Elsevier, Inc. All rights reserved. 5  Mixed dentition generally occurs between the ages of 6 and 12 years Both primary and permanent teeth MIXED are present during this transitional period DENTITION The mixed dentition period begins with the eruption of the first permanent tooth, which is a permanent mandibular first molar This period ends with shedding of the last primary tooth Copyright © 2021 by Elsevier, Inc. All rights reserved. 6 MIXED DENTITION PERIOD From Fehrenbach MJ, Popowics T: Illustrated dental embryology, histology, and anatomy, ed 4, St Louis, 2016, Saunders. Copyright © 2021 by Elsevier, Inc. All rights reserved. 7 Copyright © 2021 by Elsevier, Inc. All rights reserved. 8  The final, or adult, dentition This period begins with PERMANEN shedding of the last primary tooth T DENTITION Growth of the jawbones slows and eventually stops There is very little growth of the jaw overall during this period because puberty has passed Copyright © 2021 by Elsevier, Inc. All rights reserved. 9 FACIAL AND BUCCAL VIEW OF A PERMANENT DENTITION Copyright © 2021 by Elsevier, Inc. All rights reserved. 10  The maxillary arch (upper), which is actually part of the skull, is fixed and not capable of movement The teeth are set in the maxilla bone DENTAL The mandibular arch (lower) is capable of movement through ARCHES the action of the temporomandibular joint The mandible is the bone that supports the lower arch of teeth, hence the name mandibular arch Occlusion is the natural contact between the maxillary and mandibular teeth in all positions Copyright © 2021 by Elsevier, Inc. All rights reserved. 11 MAXILLARY ARCH Copyright © 2021 by Elsevier, Inc. All rights reserved. 12 MANDIBULA R ARCH Copyright © 2021 by Elsevier, Inc. All rights reserved. 13  Dividing the maxillary and mandibular arches into halves yields four sections, which are QUADRANTS called quadrants Each quadrant of permanent dentition contains eight permanent teeth, and a quadrant of primary dentition contains five teeth Copyright © 2021 by Elsevier, Inc. All rights reserved. 14 QUADRANTS Copyright © 2021 by Elsevier, Inc. All rights reserved. 15 SEXTANTS Sometimes it is necessary to divide the dentition into six parts, each called a sextant Maxillary right posterior Maxillary anterior Maxillary left posterior Mandibular right posterior Mandibular anterior Mandibular left posterior Copyright © 2021 by Elsevier, Inc. All rights reserved. 16 Copyright © 2021 by Elsevier, Inc. All rights reserved. 17  The anterior teeth are the incisors and canines ANTERIOR AND They are usually visible when people smile POSTERIOR TEETH (SLIDE 1 OF These teeth are aligned to form a smooth, curving arc 2) from the distal (back of the) canine on one side of the arch to the distal canine on the opposite side Copyright © 2021 by Elsevier, Inc. All rights reserved. 18  The posterior teeth are the premolars and molars ANTERIOR The posterior AND teeth are aligned POSTERIOR with little or no curvature TEETH (SLIDE 2 OF These teeth 2) appear to be in an almost straight line Copyright © 2021 by Elsevier, Inc. All rights reserved. 19  Human beings eat both meat and plants To accommodate this variety in TYPES AND diet, teeth are designed for the FUNCTIONS cutting, tearing, and grinding of different types of food OF TEETH The permanent dentition is (SLIDE 1 OF divided into four types of teeth 2) Incisors Canines Premolars Molars Copyright © 2021 by Elsevier, Inc. All rights reserved. 20  The primary dentition has: TYPES AND Incisors FUNCTION Canines S OF Molars TEETH There are no (SLIDE 2 premolars in the OF 2) primary dentition Copyright © 2021 by Elsevier, Inc. All rights reserved. 21  Single-rooted teeth with relatively sharp, thin edges Located at the front of the mouth, the incisors are INCISORS designed to cut food without the application of heavy force Incisor means “that which makes an incision or cut” The tongue side, or lingual surface, of the incisor is shaped like a shovel to help guide food into the mouth Copyright © 2021 by Elsevier, Inc. All rights reserved. 22  Canine teeth are also known as cuspids They are located at the “corners” of the arch CANINES The canines are designed for cutting and tearing food They are the longest teeth in the human dentition Canine teeth have the longest roots of all teeth and are usually the last teeth to be lost Because of its sturdy crown, long root, and location in the arch, the canine is referred to as the cornerstone of the dental arch Copyright © 2021 by Elsevier, Inc. All rights reserved. 23  There are four maxillary and four mandibular premolars The premolars, also known as bicuspids, are a cross between canines and molars The pointed buccal cusps hold PREMOLARS the food while the lingual cusps grind it The premolars are not as long as canines and also have a broader surface made for chewing food Copyright © 2021 by Elsevier, Inc. All rights reserved. 24  Molars are much larger than premolars and usually have four or more cusps The function of the 12 molars is to MOLARS chew or grind food The molars have more cusps than do the other teeth Four or five cusps on the occlusal (biting) surface of each molar, depending on the Maxillary and mandibular molars tooth’s location differ greatly from each other in shape, size, and numbers of cusps and roots Copyright © 2021 by Elsevier, Inc. All rights reserved. 25  Each tooth has five surfaces Facial TOOTH Lingual SURFACES Occlusal Mesial Distal Copyright © 2021 by Elsevier, Inc. All rights reserved. 26 Copyright © 2021 by Elsevier, Inc. All rights reserved. 27  Anatomic features of the teeth help maintain their positions in the arch and ANATOMIC protect the tissues during mastication FEATURES OF TEETH Contou rs Three anatomic Contac features ts Embras ures Copyright © 2021 by Elsevier, Inc. All rights reserved. 28  All teeth have a curved surface except when the tooth is fractured or worn Some surfaces are convex; others are concave General principle that the crown of the tooth narrows toward the cervical line is CONTOUR true for all types of teeth S Facial and lingual contours The normal contour of a tooth provides the gingiva with adequate stimulation for health, while protecting it from damage that may be caused by food Mesial and distal contours These contours provide normal contact and embrasure form Copyright © 2021 by Elsevier, Inc. All rights reserved. 29 Copyright © 2021 by Elsevier, Inc. All rights reserved. 30 CONTACTS The contact area is the area of the mesial or distal surface of a tooth that touches the adjacent tooth in the same arch A proper contact serves the following purposes: Prevents food from being trapped between the teeth Stabilizes the dental arches by holding the teeth in either arch in positive contact with each other Protects the interproximal gingival tissue from trauma during mastication Copyright © 2021 by Elsevier, Inc. All rights reserved. 31 Copyright © 2021 by Elsevier, Inc. All rights reserved. 32  The “bulge,” or widest point, on a specific surface of the crown HEIGHT OF Contact areas on the mesial and distal surfaces are CONTOUR usually considered the height of contour on the proximal surfaces Facial and lingual surfaces also have a height of contour Copyright © 2021 by Elsevier, Inc. All rights reserved. 33  When two teeth in the same arch touch, their curvatures next to the contact areas form spaces called embrasures An embrasure is a triangular space in a gingival direction EMBRASUR between the proximal surfaces of ES two adjoining teeth in contact Embrasures are continuous with the interproximal spaces between the teeth All tooth contours, including contact areas and embrasures, are important in the function and health of the oral tissues Copyright © 2021 by Elsevier, Inc. All rights reserved. 34 Copyright © 2021 by Elsevier, Inc. All rights reserved. 35  Line and point angles are used only as descriptive terms to indicate specific locations Line angle: Formed by the ANGLES AND junction of two surfaces Named from the DIVISIONS combination of the two OF TEETH surfaces that join Point angle: Angle formed by the junction of three surfaces at one point Named from the combination of surfaces that form them Copyright © 2021 by Elsevier, Inc. All rights reserved. 36 Copyright © 2021 by Elsevier, Inc. All rights reserved. 37 DIVISIONS Each tooth surface is INTO THIRDS divided into imaginary thirds (SLIDE 1 OF to help identify a specific 2) area of the tooth Copyright © 2021 by Elsevier, Inc. All rights reserved. 38  Root of tooth Apical third Middle third Cervical third DIVISIONS Crown of tooth INTO THIRDS Occlusocervical division Crosswise division parallel to (SLIDE 2 OF occlusal surface 2) Mesiodistal division Lengthwise division in a mesial- distal direction Buccolingual division Lengthwise division in a labial or buccal-lingual direction Copyright © 2021 by Elsevier, Inc. All rights reserved. 39 OCCLUSION P. 136 MDA Occlusion is the relationship of the maxillary and mandibular teeth when the jaws are in a fully closed position. Occlusion develops in a child as the primary teeth erupt. Habits such as thumb sucking or improper swallowing habits can affect the occlusion. Proper occlusion of the erupting permanent teeth depend on the occlusion of the primary teeth as they are shed Copyright © 2021 by Elsevier, Inc. All rights reserved. 40 TYPES OF OCCLUSION Centric occlusion: The jaws are closed in a position that produces maximal stable contact between the occluding surfaces of the maxillary and mandibular teeth. Functional occlusion: The contact of the teeth during biting and chewing movements. Malocclusion: Abnormal or malpositioned relationships of the teeth. Copyright © 2021 by Elsevier, Inc. All rights reserved. 41  Used to describe and classify occlusion and malocclusion ANGLE’S Basis of system is that CLASSIFICATION the permanent maxillary first molar is the key to occlusion Assumes that the patient is occluding in a centric position Copyright © 2021 by Elsevier, Inc. All rights reserved. 42 Copyright © 2021 by Elsevier, Inc. All rights reserved. 43  Class I (neutroclusion): An ideal mesiodistal relationship exists between the jaws and the dental arches CLASSES OF Mesiobuccal cusp of permanent maxillary MALOCCLUSION first molar occludes with mesiobuccal groove of mandibular first molar Class II (distoclusion): Mesiobuccal cusp of maxillary first molar occludes (by more than the width of a premolar) mesial to the mesiobuccal groove of mandibular first molar Frequently gives the appearance of protrusion of the maxillary anterior teeth over the mandibular anterior teeth Copyright © 2021 by Elsevier, Inc. All rights reserved. 44 45 DIVISIONS OF CLASS II MALOCCLUSION Division 1: Lips are usually flat and parted, with the lower lip tucked behind the upper incisors Maxillary incisors are in labioversion Division 2: Maxillary incisors are not in labioversion Maxillary central incisors are nearly normal anteroposteriorly, and they may be slightly in linguoversion Copyright © 2021 by Elsevier, Inc. All rights reserved. 45 46 CLASS III MALOCCLUSION (MESIOCLUSION) The body of the mandible must be in an abnormal mesial relationship to the maxilla Frequently gives the appearance of protrusion of the mandible Copyright © 2021 by Elsevier, Inc. All rights reserved. 46 CLASS I Class I (neutroclusion): An ideal mesiodistal relationship exists between the jaws and the dental arches Mesiobuccal cusp of permanent maxillary first molar occludes with mesiobuccal groove of the mandibular first molar Copyright © 2021 by Elsevier, Inc. All rights reserved. 47 IDEAL CLASS ---CLASS I OCCLUSION Copyright © 2021 by Elsevier, Inc. All rights reserved. 48 CLASS I Copyright © 2021 by Elsevier, Inc. All rights reserved. 49 Copyright © 2021 by Elsevier, Inc. All rights reserved. 50 CLASS II Class II (distoclusion): Mesiobuccal cusp of maxillary first molar occludes (by more than the width of a premolar) mesial to the mesiobuccal groove of mandibular first molar Frequently gives the appearance of protrusion of the maxillary anterior teeth over the mandibular anterior teeth Copyright © 2021 by Elsevier, Inc. All rights reserved. 51 CLASS II Copyright © 2021 by Elsevier, Inc. All rights reserved. 52 Copyright © 2021 by Elsevier, Inc. All rights reserved. 53 Copyright © 2021 by Elsevier, Inc. All rights reserved. 54 Copyright © 2021 by Elsevier, Inc. All rights reserved. 55 CLASS III MALOCCLUSION (MESIOCLUSION) The body of the mandible must be in an abnormal mesial relationship to the maxilla Frequently gives the appearance of protrusion of the mandible Copyright © 2021 by Elsevier, Inc. All rights reserved. 56 CLASS III Class lll- Mesiobuccal cusp of the maxillary first molar occludes distal to the mesiobuccal groove of the mandibular first molar. Copyright © 2021 by Elsevier, Inc. All rights reserved. 57 CLASS III Copyright © 2021 by Elsevier, Inc. All rights reserved. 58 Copyright © 2021 by Elsevier, Inc. All rights reserved. 59 Copyright © 2021 by Elsevier, Inc. All rights reserved. 60 Copyright © 2021 by Elsevier, Inc. All rights reserved. 61  Closure: Anterior teeth are not designed to fully support the occlusal forces on the entire dental As the jaws close, the stronger arch posterior teeth come together STABILIZATIO first N OF THE ARCHES (SLIDE 1 OF 2) Curve of Spee: Occlusal surfaces of the posterior teeth do not form a flat plane The curvature formed by the maxillary and mandibular arches in occlusion is known as the curve of Spee Copyright © 2021 by Elsevier, Inc. All rights reserved. 62 STABILIZATION OF THE ARCHES (SLIDE 2 OF 2) Curve of Wilson Cross-arch curvature of the posterior occlusal plane Downward curvature of the arc is defined by line drawn across occlusal surface of the left mandibular first molar Copyright © 2021 by Elsevier, Inc. All rights reserved. 63 TOOTH-NUMBERING SYSTEMS Numbering systems are used as a simplified means of identifying the teeth for charting and descriptive purpose Universal/National System International Standards Organization System Palmer Notation System Copyright © 2021 by Elsevier, Inc. All rights reserved. 64  Used most often in the United States UNIVERSAL/NATIONAL Permanent teeth are numbered SYSTEM from 1 to 32 Numbering begins with the upper-right third molar and works around to the upper-left third molar Then numbering drops to the lower-left third molar and works around to lower-right third molar Copyright © 2021 by Elsevier, Inc. All rights reserved. 65  The ISO/FDI System uses a two-digit tooth-recording system INTERNATIONAL First digit indicates the STANDARDS quadrant ORGANIZATION SYSTEM Second digit indicates the tooth within the quadrant, with numbering from the midline toward the posterior Copyright © 2021 by Elsevier, Inc. All rights reserved. 66  Each of the four quadrants is given its own tooth bracket made up of a PALMER vertical line and a horizontal NOTATION line SYSTEM A shorthand diagram of the teeth presented as if one is viewing the patient’s teeth from the outside Copyright © 2021 by Elsevier, Inc. All rights reserved. 67 QUESTIONS? Copyright © 2021 by Elsevier, Inc. All rights reserved. 68