Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 1 PowerPoint ® Presentation for Chairside Dental Assisting with Labs Module: Embryology

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 2 Module: Embryology Embryology Part A: Oral Embryology Part B: Histology

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 3 Module: Embryology Learning Objectives 1. Define the Key Terms. 2. Identify the three prenatal phases of pregnancy. 3. Describe the life cycle of a tooth and the stages of development. 4. State the substances making up enamel, dentin, cementum, and pulp.

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 4 Module: Embryology Learning Objectives 5. List the structures of the gingiva 6. Explain the location and function of the four primary tooth structures.

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 5 Key Terms Alveolar crest Alveolar mucosa Alveolar process Alveolus Ameloblasts Attached gingiva Attrition Calcification Cementoblasts Cementum Cleft palate Cleft uvula Dentin Dentinal tubules Enamel

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 6 Key Terms Epithelial attachment Fibroblasts Free gingiva Gingiva Gingival sulcus Lamina dura Mucogingival junction Nasmyth’s membrane Odontoblasts Periodontium Philtrum Pulp Sharpey’s fibers Stomedeum Zygote

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 7 Part A: Oral Embryology Study of developmental stages of the individual Prenatal Natal Postnatal Zygote: First 2 wks Embryo: 2 wks-8wks Fetus: 9 wks-birth

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 8 Fertilization Cell division and specialization Proliferation Cytodifferentiation Histodifferetiation Morphodifferentiation

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 9 Embryonic Stage Three primary embryonic cell layers Oral cavity and teeth derived from ectoderm

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 10 Factors Influencing Prenatal Development Genetic Environment

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 11 Palatal Development Formed during week 5 or 6 Cleft palate Cleft lip Unilateral or bilateral Opening in hard or soft palate Missing or malaligned teeth

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 12 Life Cycle of a Tooth Intitiation Bud stage Proliferation Cap stage Histodifferentiation Bell stage Morphodifferentiation

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 13 Developmental Problems Ameloblastomas Anodontia Supernumerary Osteodentin Dentinogenesis imperfecta Amelogenesis imperfecta Macrodontia Microdontia Twinning Hutchinson’s incisors Enamel hypoplasia Hypocalcification Mottled enamel Tetracycline staining

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 14 Eruption Period Problems Impaction Malpositioned teeth Ankylosis Functional Prefunctional

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 15 Factors Contributing to Tooth Eruption Pressure as roots form Formation and resorption of bone Pressure of muscles Growth of roots Formation of crown Tooth eruption

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 16 Maturation Stage Attrition Bruxism Erosion Abrasion

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 17 Part B: Histology of Enamel Formed by ameloblasts 95% mineralized inorganic material 5% organic 98% calcified Consists of enamel rods or prisms Yellow to grayish white Strong yet prone to splits and chips Hardest structure in body Non-reparative Subject to caries Subject to wear

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 18 Histology of Dentin Formed by odontoblasts 70% inorganic matter 30% organic matter Makes up bulk of tooth Dentinal tubules Not as hard as enamel Somewhat elastic Pale yellow Somewhat transparent More radiolucent than enamel Can repair itself

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 19 Histology of Dentin Primary dentin Secondary dentin Tertiary dentin

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 20 Histology of Pulp Layer of odontoblasts line pulp cavity Blood and lymph vessels, nerve fibers Production of dentin via odontoblasts Nutrition Sensory Defense

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 21 Histology of Cementum Formed by cementoblasts Covering of root 50% to 55% inorganic material 45% organic Primary cementum Secondary cementum Anchors tooth to socket via periodontal ligaments Hypercementosis Cementoclasia

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 22 Histology of the Alveolar Process Alveolar process – bone supporting teeth Cancellous bone Cortical plate Socket Interdental septum Interradicular septum Alveolar crest Lamina dura Sensory Supportive Nutritive Formative Periodontitis Periodontosis

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 23 Histology of Periodontal Ligament Bundles of connective tissue Extends from cementum to alveolar bone Supportive Formative Sensory Nutritive Resorptive Ankylosis Loss of function

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 24 Histology of Gingiva Mucous membrane Surrounds tooth in collar-like fashion Self cleaning Firm and resistant Tightly adapted to tooth and bone Surface stippled Protects delicate tissues Aids in chewing Protects against bacteria Gingivitis Periodontitis Periodontosis

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 25 Assessment Questions What takes place following fertilization? Cell division and specialization From which embryonic layer are the oral cavity and teeth derived? From the ectoderm What is the bone that supports the teeth? The alveolar process

Copyright © 2006 Thomson Delmar Learning. ALL RIGHTS RESERVED. 26 Summary of Module Key Terms Oral embryology and histology