Dentin Pauline Hayes Garrett, D.D.S. Department of Endodontics, Prosthodontics, and Operative Dentistry University of Maryland, Baltimore

This material was taken from: Essentials of Oral Histology and Embryology, third edition, Leslie P Gartner, 1999, Jen House Publishing Co. Chapter 3 Ten Cate’s Oral Histology Development, Structure, and Function, Antonio Nanci, sixth edition, 2003, Mosby, Chapter 8

Objectives: To recognize and apply the following concepts to clinical dentistry: Physical Properties of Dentin Dentinal Tubules Peritubular Dentin Intertubular Dentinal Types of Dentin Peritubular Intertubular Primary Dentin Secondary Dentin Tertiary Dentin Dead Tracks Sclerotic Dentin Globular Dentin Interglobular Dentin Markings on Dental Tubules Daily imbrication lines of von Ebner Contour Lines of Owen Neonatal line Dentin Intervention Granular layer of Tomes Hyline layer of Hopewell-Smith Root Dentin Nerve Fiber Theory Odontoblastic process Theory Hydrodynamic Theory

Physical Properties of Dentin Dentin :located in crown and root. 65-70% mineralized substances 20-25% organic material 10% bound water. The mineralized :calcium hydroxyapatite. The organic material :collagen and ground substance. Color: yellow. Highly elastic: support substance for Enamel Dentin is living tissue. The odontoblasts reside in the pulp and continue to be active throughout the life of the tooth. Illustration reprinted and modified from: Oral Histology and Embryology, second edition, Gartner, 1999 pg. 46. with permission from Dr. Leslie P. Gartner

Dentinal Tubules Enclosed spaces Surrounded by peritubular dentin A scanning electron microscope specimen of dentinal tubules. Reproduced with permission from Mathias Nordve, IOB,UiO, University of Oslo.

Dentinal Tubules Primary Curvature is: S-shaped Secondary Curvature: jagged or wrinkled texture Curvatures result from movement of odontoblasts during development

Coronal portion= “S”shaped curvature. Vs. Root portion= more Straight path.

Dentinal Tubules “S” shape primary curvatures of coronal dentin on the right. Photomicrograph of decalcified dentin and illustration below, show the second degree curves in dentin Histological slides prepared and provided by the Department of Biomedical Sciences, University of Maryland, Dental School.

Dentinal Tubules, Peritubular dentin and Intertubular dentin Dentinal tubules contain = extracellular fluid (ECF) - From pulp and provides nutrients - From the pulp to the DCJ or DEJ - Important for pain sensation

Dentinal Tubules, Peritubular dentin and Intertubular dentin A scanning electron microscope specimen of dentinal tubules. Reproduced with permission from Mathias Nordve, IOB,UiO, University of Oslo.

Types of Dentin - Primary Dentin: - Secondary Dentin: all dentin formed prior to root formation or completion. - Secondary Dentin: all dentin produced after root formation or completion. (NOT due to trauma) - Tertiary Dentin: all reparative dentin (all regular and irregular)*

Types of Dentin: Primary Dentin Two Types: All collagen in Dentin is produced by Odontoblasts. Mantle Dentin (M) is the first formed dentin. It is located in both the crown underlying the DEJ and the root of the tooth. ~20 micrometers thick. Fibers are perpendicular to the DEJ. Contains von Korff’s fibers Circumpulpal dentin: the remaining and the bulk of primary dentin. The collagen fibers are much narrower (~0.05 micrometers thick) than mantle dentin.. It is more mineralized than mantle dentin. It is more compactly arranged collagen fibers than mantle dentin.. Mantle Dentin (M arrow) Ameloblasts (A), Odontoblasts (O). Histological slide prepared and provided by the Department of Biomedical Sciences, University of Maryland, Dental School.

Types of Dentin: Secondary Dentin around the pulp chamber subsequent to root completion. not a response to trauma. formed at a slower rate than primary dentin. fewer tubules than primary dentin. formed in an unequal fashion more on the roof and floor of the pulp than on the walls. usually has a bend in the direction of the tubules where primary and secondary meet. Image reprinted from the Leeds University: The Virtual Oral Histology Laboratory

Types of Dentin: Tertiary Dentin Reparative Dentin: 2 kinds: regular irregular Histological slide prepared and provided by the Department of Biomedical Sciences, University of Maryland, Dental School.

Types of Dentin: Dead Tracks Dead Tracts are empty dentinal tubules that lead directly to pulp Due primarily to caries

Types of Dentin: Sclerotic Sclerosis minerals within tubules. highly mineralized Deposited inside tubules. The tubules smaller in diameter less permeable transmit stimuli to a lesser degree. Image reprinted from the Leeds University: The Virtual Oral Histology Laboratory

Types of Dentin: Globular vs. Interglobular Dentin Arrows = interglobular dentin. Histological slide prepared and provided by the Department of Biomedical Sciences, University of Maryland, Dental School.

Markings on Dentin Tubules: Segments = Contour Lines of Owen Lengthwise section of a Dentin tubule Striations = Daily Imbrication Lines of Von Ebner

Dentin: Granular layer of Tomes/ Hyaline layer of Hopewell-Smith In peripheral most layer of radicular dentin. Hyaline of Hopewell- Smith Clear layer between the granular layer of Tomes and cementum Facilitates the adherence of cementum and dentin. Histological slides prepared and provided by the Department of Biomedical Sciences, University of Maryland, Dental School.

Root Dentin Lines of Owen. (O arrows) The radiating lines represent dentinal tubules (T arrows) The light semicircular line is called the hyaline layer of Hopewell-Smith (H) The thin dark line is the dentinocemental juntion. The cementum (C) Periodontal ligament (P) is cementoid (uncalcified cementum). Cross section of a decalcified root

Clinical Significance: Natural Desensitization Sclerosis of dentin Secondary Tertiary dentin.

Clinical Significance: Tetracycline staining and Bleaching

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