Transcript Chapter 08
8 Embryology and Histology Embryology • Study of the prenatal growth and development process of an individual 2 Embryology • Three prenatal phases during pregnancy: – Zygote • Conception - 2 weeks – Embryo • 2 - 8 weeks – Fetus • 9 weeks - birth 3 Embryonic Layers • Ectoderm • Mesoderm • Endoderm 4 Embryonic Layers 5 Primitive Facial Development • Frontonasal process • Maxillary process • Mandibular process 6 Stages of Pregnancy • First Trimester (0 - 12 weeks) – Major organ structures are developing • Second Trimester (13 – 28 weeks) – Fetus with features grows rapidly • Third Trimester (29 – 40 weeks) – Head drops down preparing for life outside 7 Developmental Disturbances • Genetic and environmental factors – Drugs – Infections – Fetal Alcohol Syndrome 8 Development Disturbances Cleft uvula Philtrum Lip Incisive papillae Hard palate Soft palate Cleft uvula 9 Development Disturbances Bilateral cleft of the secondary palate Nasal cavity Nasal septum 10 Development Disturbances Unilateral cleft lip, primary palate, and alveolar process Philtrum Lip Primary palate Alveolar process Secondary palate 11 Development Disturbances • Cleft lip and palate Bilateral cleft of the lip, alveolar process, and primary palate Bilateral cleft of the lip, alveolar process, and primary and secondary palate Philtrum Lip Primary palate Alveolar process Secondary palate 12 Histology • General Histology • Oral Histology – Stages – Tissues – Structures 13 Life Cycle of the Tooth • Bud stage – Initiation • Cap stage – Proliferation 14 Life Cycle of the Tooth • Bell stage – Histodifferentiation – Morphodifferentiation 15 Life Cycle of the Tooth • Maturation stage – Apposition – Calcification – Eruption – Attrition 16 Tooth Structure • Four primary structures of the tooth – Enamel – Dentin – Cementum – Pulp 17 Tissues of the Tooth Pulp horns Enamel Pulp chamber Pulp Dentin Pulp canal Cementum 18 Enamel • Enamel rod – Head and tail • Tome’s process 19 Enamel • Lines of Retzius – Neonatal – Imbrication – Perikymata 20 Enamel • Enamel spindles – Enamel tufts – Enamel lamellae 21 Enamel • Enamel dysplasia – Grooved and pitted teeth due to malnutrition – Restorative work 22 Dentin • Yellowish undertone • Fluid passes through tubules • Developmental marks – Dentinal hypersensitivity – Imbrication lines of Von Ebner – Contour lines of Owen – Neonatal Line 23 Dentin • Types of dentin – Peritubular – Intertubular – Mantle – Circumpulpal – Primary – Secondary – Tertiary 24 Pulp • Fibroblasts • Intercellular substances • Pulpitis – Inflamed tissue due to injury – Pressure can not escape – Root canal opens and releases pressure 25 Pulp • Pulp stones – Calcified masses of dentin – Very common 26 Cementum • Softer and grainy • No regeneration – Allows for orthodontic treatment – Movement without destruction • Sharpey’s fibers 27 Alveolar Bone • Osteoblasts and Osteoclasts • Alveolar process – Cortical bone, Alveolus, Lamina dura • Alveolar Crest 28 Alveolar Bone • Clinical concerns – Periodontal disease can cause bone loss – Implants are option if teeth are removed 29 Periodontal Ligament Interdental fiber group Alveolar crest fiber group Alveolar crest Horizontal fiber group Alveolar bone Dentin Alveolus (lamina dura) Oblique fiber group Interradicular septum Apical fiber group Interdental bone Interradicular fiber group Cementum 30 Periodontal Fiber Groups • • • • • • Alveolar crest Horizontal Oblique Apical Interradicular Interdental ligament 31 Gingival Fiber Groups • • • • Dentogingival Circular ligament Alveologingival Dentoperiosteal 32 Gingiva • Commonly referred to as gums • Texture and color • Clinical considerations – Gingival hyperplasia is overgrowth of gum tissue – Can appear red and swollen – Can usually be treated with better hygiene 33 Gingiva Gingival groove Marginal gingiva Interdental gingiva Attached gingiva Mucogingival junction Alveolar mucosa 34