Dental Anatomy and Terminology Landmarks and Tooth Numbering Systems PDF

Dental Anatomy and Terminology Landmarks, Fundamental and Preventive Curvatures and Tooth Numbering Systems Valerie Baldwin RDH, CAE Canadian National Institute of Health Inc. 1 Review https://quizlet.com/224310136/divisions-of-the- tooth-flash-cards/ C...

Dental Anatomy and Terminology Landmarks, Fundamental and Preventive Curvatures and Tooth Numbering Systems Valerie Baldwin RDH, CAE Canadian National Institute of Health Inc. 1 Review https://quizlet.com/224310136/divisions-of-the- tooth-flash-cards/ Canadian National Institute of Health Inc. 2 Resources Brand, R.W., Isselhard, D.E. & Smith, A.N. (2024). Anatomy of orofacial structures: A comprehensive approach (9th ed.). Elsevier. Bowen, D.M., & Pieren, J.A. (2020). Darby & Walsh dental hygiene: Theory and practice. (5th ed.) Philadelphia, PA: Elsevier Saunders Fehrenbach, M., & Popowics, T. (2015). Illustrated dental embryology, histology, and anatomy. (4th ed.). St. Louis, MO: Elsevier Saunders Canadian National Institute of Health 3 Inc. Terminology Concavity - A depression in a surface Convexity - A bulge in a surface Canadian National Institute of Health Inc. 4  Landmarks Cusp A pointed or rounded elevation of enamel that makes up a major division of its occlusal or incisal surface. Vary in their size and number from tooth to tooth Found on canines, premolars and molars. Canadian National Institute of Health Inc. 5  Landmarks Lobes All teeth are formed from lobes Each tooth forms from 4 or more lobes Lobes are growth centers. The lobes grow and eventually fuse, but a line remains on the erupted tooth where the fusion took place. Canadian National Institute of Health Inc. 6  Landmarks Developmental Groove Fine depressed lines in the enamel of a tooth that marks the union of the lobes of the crown. Long in length and well defined. Named according to the direction they face. As the enamel develops and spreads laterally, it touches enamel developing from other lobes. This junction forms a developmental groove. Such grooves appear on the labial, buccal, and lingual surfaces, and are least apparent on the labial aspect of anteriors. Canadian National Institute of Health Inc. 7  Landmarks Supplemental Groove minor, auxiliary groove branches off from a much more prominent developmental groove. do not represent the junction of primary tooth parts gives the occlusal surface a wrinkled appearance. Canadian National Institute of Health Inc. 8 Landmarks Mamelon One of the three rounded protuberances (bumps) of the incisal surface of a newly erupted incisor tooth. After eruption they are soon worn down leaving a smooth incisal surface. Canadian National Institute of Health Inc. 9  Landmarks Tubercle Small elevation of enamel on some portion of the crown of tooth not always on the lingual surface ; can occur on labial or occlusal surface. Canadian National Institute of Health Inc. 10 Landmarks Fossa Depression or concavity Named for their location (direction that they face) Vary in size and depth Found on the lingual surfaces of all anterior teeth and on the occlusal surface of posterior teeth Central Fossa Centrally located depression found on the occlusal surface of molars and mandibular second premolars. Canadian National Institute of Health Inc. 11 Landmarks Lingual Fossa Irregular, shallow depression found on the lingual surfaces of an incisor or cuspid. (Courtesy of Leeds University) http://www.dentistry.leeds.ac.uk/oroface/teeth/choice.html Canadian National Institute of Health Inc. 12 Landmarks Triangular Fossa Located adjacent to the marginal ridges on the occlusal surfaces of posterior teeth. Two types of triangular fossae are mesial and distal. Canadian National Institute of Health Inc. 13 Landmarks Pit Pinpoint hole within fossa or anywhere on the tooth Usually occur along developmental grooves or in the fossae Named for their location on the tooth Canadian National Institute of Health Inc. 14 Landmarks Fissure A developmental line fault usually found in the occlusal or buccal surface of a tooth; commonly the result of the imperfect fusion of the enamel of the adjoining dental lobes. Canadian National Institute of Health Inc. 15 Landmarks Cingulum Found on the lingual aspect of an anterior tooth. It is a convex mount of enamel localized to the cervical one-third of the crown. Lingual lobe of anterior teeth. (Courtesy of Leeds University) http://www.dentistry.leeds.ac.uk/oroface/teeth/choice.html Canadian National Institute of Health Inc. 16 Landmarks Ridges Elevated portion of enamel on a tooth that runs in a line. Found on crowns of both anterior and posterior teeth. Lingual Ridge The ridge of enamel that extends from the cingulum to the cusp tip on the lingual surface of most cuspids. Canadian National Institute of Health Inc. 17  Landmarks Marginal Ridge Are the rounded borders of enamel that form the mesial and distal shoulders of the occlusal surfaces of the posterior teeth and the mesial and distal shoulders of the lingual surfaces of the anterior teeth. (Courtesy of Leeds University) http://www.dentistry.leeds.ac.uk/oroface/teeth/choice.html Canadian National Institute of Health Inc. 18 Landmarks Triangular Ridge Main ridges on each cusp that run from the tip of the cusp to the central part of the occlusal surface It is a convexity or bulge. Canadian National Institute of Health Inc. 19 Landmarks Transverse Ridge The union of two triangular ridges, a buccal and lingual, that cross the occlusal surface of a posterior tooth. Canadian National Institute of Health Inc. 20 Landmarks Oblique Ridge The only tooth on which an oblique ridge is found is the maxillary molars. Consists of an elevated prominence on the occlusal surface and extends obliquely from the tips of the mesiolingual cusp to the distobuccal cusp. Canadian National Institute of Health Inc. 21  Fundamental and Preventive Curvatures Specific Functions of Curvatures: 1. Prevent disease 2. Prevent damage 3. Prevent bacterial invasion 4. Prevent calculus build up 5. Disperse excessive occlusal trauma and biting forces 6. Protect gingiva and periodontium (supporting structures of the teeth) 7. Align and stabilize the entire dentition (teeth position in the jaw) Canadian National Institute of Health Inc. 22 Fundamental and Preventive Curvatures Specific Curvatures: 1. Proximal Contact Areas 2. Interproximal Spaces 3. Embrasures – Spillways 4. Facial and Lingual Contours of the Tooth 5. Curve of Path of CEJ Around Each Tooth 6. Self Cleansing Qualities of the Teeth Canadian National Institute of Health Inc. 23 Fundamental and Preventive Curvatures 1. Proximal Contact Areas Areas on the surfaces of the teeth where the proximal surfaces touch one another. Why proximal contact areas? Prevents food from packing between the teeth. Protects underlying gum tissue between the teeth. Offer support and anchorage to one another and resistance to displacement from traumatic forces. Canadian National Institute of Health Inc. 24 Fundamental and Preventive Curvatures 1. Proximal Contact Areas (cont.) Two teeth share interproximal bone so if something happens to cause the loss of bone, this can affect both teeth. The proximal contact areas are located on the mesial and distal surfaces of each tooth at the widest portion and the greatest curvature = Height or Crest of Curvature. Canadian National Institute of Health Inc. 25 Fundamental and Preventive Curvatures General Rules Regarding Contact Areas 1. Contacts become more cervically located from anterior to posterior in each quadrant – go from incisal to middle. 2. The distal contact is more cervically located than the mesial contact in each tooth. 3. The actual size of the contact area will increase from anterior to posterior. 4. Anterior contacts are somewhat centered on the proximal surface. 5. Posterior contacts are somewhat buccal (towards the facial). Canadian National Institute of Health Inc. 26 Fundamental and Preventive Curvatures Contact Point Differs from a contact area Occlusal cusp of one tooth touches the occlusal portion of another tooth in the opposing arch. Contact point of an upper tooth hits (occludes and makes contact with) the contact point of a lower tooth. Canadian National Institute of Health Inc. 27 Fundamental and Preventive Curvatures 2.Interproximal Spaces Triangular shaped spaces between the teeth Normally filled with gingiva – keeps the food from collecting cervically to the contact areas between the teeth Functions: 1.Prevents food and debris from filling the contact area – if the space is only partially filled with gingiva, the food will collect between the teeth. 2.Provides for a bulk of bone for better anchorage and support and allows for a richer blood supply and nourishment When the interproximal space has lost its interdental papilla = Cervical Embrasure. Canadian National Institute of Health Inc. 28 Fundamental and Preventive Curvatures 2. Interproximal Spaces (cont.) Boundaries: Apex of interproximal space is formed by a contact area Sides of the space are formed by the proximal surfaces of the teeth The base of the triangle is the alveolar bone Canadian National Institute of Health Inc. 29 Fundamental and Preventive Curvatures 2. Interproximal Spaces (cont.) Cervical Embrasure When recession and disease occur between the teeth, papilla and bone no longer fills the entire space. A void exists and this space is called cervical embrasure It is a space where bacteria, calculus and food debris can accumulate. Canadian National Institute of Health Inc. 30 Fundamental and Preventive Curvatures 2. Interproximal Spaces (cont.) Interdental Papilla Projection of gingiva between the teeth Keeps food from collecting cervically to the contact areas between teeth. Canadian National Institute of Health Inc. 31 Fundamental and Preventive Curvatures 3. Embrasures (Spillways) Spaces between the teeth that are occlusal to the contact area Named for their location in relation to the contact area. The names are buccal, lingual, incisal or occlusal Functions of Embrasures: 1. Allow for passage of food around teeth so that food is not forced into the contact area 2. Dissipate and reduce the forces of occlusal trauma 3. Self- cleaning (rounded and smooth) 4. Permit slight amount of stimulation to the gingiva by frictional massage Canadian National Institute of Health Inc. 32 Fundamental and Preventive Curvatures 3. Embrasures (Spillways) (cont.) Canadian National Institute of Health Inc. 33 3. Embrasures (Spillways) (cont.) Canadian National Institute of Health Inc. 34 Embrasures (Spillways) (cont.) Size of Embrasures Strictly related to the location of the contact areas. As the contact areas become more cervically located from anterior to posterior, the incisal and occlusal embrasures become larger and the cervical embrasures get smaller. Lingual embrasure is the largest. Reason is that from their contact point outward, teeth are narrower on the lingual side than on the facial side. Canadian National Institute of Health Inc. 35  Fundamental and Preventive Curvatures 4. Facial and Lingual Contours of the Tooth The correct degree of facial or lingual curvature allows for the proper deflection of food so that the right amount of tissue stimulation occurs, and the gingival crevices are protected The contour on the lingual surface should allow the tongue to rest against the teeth to promote the most efficient cleaning. The facial height of contour allows for maximum cleaning of the lips and cheeks. Canadian National Institute of Health Inc. 36 Fundamental and Preventive Curvatures Crest of Curvature/Height of Contour Widest part of the crown. Facial & Lingual Height of Contour on Teeth: Facial Surfaces of all teeth – Cervical third Lingual Surfaces of Anterior teeth – Cervical third Lingual Surfaces of Posterior teeth – Middle Third Canadian National Institute of Health Inc. 37 Heights of Curvature Canadian National Institute of Health Inc. 38  Fundamental and Preventive Curvatures Undercontoured areas – Food is forced onto and between the gingival sulcus therefore traumatizing the tissue = gingival breakdown. Overcontoured areas (caused by restorations – overhanging restorations) – Food flow is totally away from the gingiva therefore allowing no stimulation/inadequate stimulation = gingival breakdown. Canadian National Institute of Health Inc. 39 Degrees of Contours Canadian National Institute of Health Inc. 40 Fundamental and Preventive Curvatures 5. Curvature of the Cementoenamel Junction Curvature of the cervical line or cementoenamel curvature Importance: 1. Separates enamel of the crown from the cementum of the root. 2. Healthy gingival tissue is right near the CEJ about 1mm. 3. Important clinically for effective instrumentation and avoidance of tissue injury. The CEJ level is: 1) directly related to contact areas of teeth 2) related to the width of the crown. Canadian National Institute of Health Inc. 41 Fundamentals and Preventive Curvatures Curvature of the CEJ (cont.) With Anterior Teeth –The CEJ coincides with the projection of bone and that is why the CEJ is higher. Anterior teeth are long and slender therefore need more support. With Posterior Teeth – The teeth are wide and short and as you move posteriorly the mandible and the maxilla widens. These both allow for good support, therefore the CEJ curvature is less and the contacts are located in the middle third. Canadian National Institute of Health Inc. 42 Fundamentals and Preventive Curvatures Rules Pertaining to CEJ Curvature 1. The cervical line is curved convex toward the apex on facial and lingual surfaces. 2. The CEJ is curved convex toward the incisal or occlusal on the proximal surfaces. 3. The depth of the curve is greatest on the mesial and less on the distal by approximately 1mm. 4. The depth of curvature on all surfaces is greatest on the central incisors and decrease posteriorly. Canadian National Institute of Health Inc. 43 Fundamentals and Preventive Curvatures 6. Self Cleansing Qualities of Teeth Reasons: 1) Crowns of the teeth are covered by a very smooth enamel. 2) The shape of the crown Rules: 1. Proper contour will assist in the cleansing and stimulation of the gingiva and this will assist in the prevention of periodontal disease. 2. Smooth enamel prevents food from sticking to the teeth, in turn this helps prevent tooth decay. 3. The surface is hardest to clean next to the proximal surfaces and occlusal is the next hardest to clean. Note: Most decay on teeth occur in the proximal and occlusal surfaces. Canadian National Institute of Health Inc. 44 Arrangement of Teeth Primary dentition/ 20 deciduous teeth Deciduous dentition (Baby teeth) Secondary dentition 32 permanent teeth (Permanent teeth) Maxillary teeth Teeth in the upper jaw, 16 Mandibular teeth Teeth in the lower jaw, 16 Canadian National Institute of Health Inc. 45 Arrangement of Teeth Quadrant There are 4 quadrants, each arch is divided into two: Canadian National Institute of Health Inc. 46  Arrangement of Teeth Sextants There are 6 sextants, each arch divided into three. Divisions created between the front (anterior) teeth and the back (posterior) teeth. Canadian National Institute of Health 47 Inc. Naming and Coding Teeth When identifying a tooth list the following: 1) Dentition 2) Arch 3) Quadrant 4) Tooth Example: Permanent mandibular right central incisor. Canadian National Institute of Health Inc. 48 Tooth Numbering Systems Developed to simplify the task of identifying individual teeth without using their full name Three Systems: 1. Universal Numbering System 2. International Numbering System FDI 3. Palmer Notation System Canadian National Institute of Health Inc. 49 Universal Numbering System Teeth are numbered 1 through 32 starting with maxillary right permanent third molar designated as tooth #1. The left mandibular third molar designated as tooth #17. Primary dentition is identified in the same order however alphabetical letters are used: A to T Canadian National Institute of Health Inc. 50 Universal Numbering System – Permanent Dentition Canadian National Institute of Health Inc. 51 Universal Numbering System – Primary Dentition Canadian National Institute of Health Inc. 52 International Numbering System FDI Uses a two digit system First digit identifies the quadrant , the second digit identifies the tooth. Permanent quadrants 1-4. Primary quadrants 5-8. Permanent teeth 1-8 starting with the central incisor being 1. Primary teeth 1-5 starting with the central incisor being 1. Canadian National Institute of Health Inc. 53 International Numbering System FDI Canadian National Institute of Health Inc. 54  Palmer Notation System Each of the four quadrants is given its own prefix symbol or quadrant bracket. Numbers or letters should be placed in a bracket with a line to their immediate right as the practitioner views it. This line indicates the midline. The number or letter assigned to each tooth depends on its position relative to the midline. For example, the central incisors, the teeth closest to the midline, have the lowest number- that is, the number 1 for permanent teeth and the letter A for deciduous teeth. Canadian National Institute of Health Inc. 55 Palmer Notation System Permanent Dentition Canadian National Institute of Health Inc. 56 Review of Landmarks https://quizlet.com/16830964/flashcards Canadian National Institute of Health Inc. 57