Chapter 12, 13, 14 - Enamel, Dentin, Pulp PDF

ENAMEL Chapter 12 Exam 4 Objectives ◦Define and pronounce the key terms in this chapter. ◦Describe the enamel properties and the clinical considerations concerned with enamel structure, integrating it into patient care. ◦Discuss the process involved in the apposition and maturation stages of...

ENAMEL Chapter 12 Exam 4 Objectives ◦Define and pronounce the key terms in this chapter. ◦Describe the enamel properties and the clinical considerations concerned with enamel structure, integrating it into patient care. ◦Discuss the process involved in the apposition and maturation stages of enamel as well as the clinical considerations concerned with enamel formation and pathology, integrating it into patient care. ◦Identify the components of the enamel on a diagram. ◦Discuss the histology of enamel and the clinical considerations for dental procedures concerning enamel, integrating it into patient care. COMPOSITION Crystalline Calcium 96% Mineralized=hardness Hydroxyapatite (main component (Inorganic) in mineralization) 3% Water 1% Organic Matrix  Levels Enamel Dentin Cementum Alveolar Enamel Bone ◦The calcium ~Mineral levels 96% 70% 65% 60% hydroxyapatite is similar to that found in lesser 1% 20% 23% 25% ~ Organic and percentages in water levels organic, organic, organic, organic, dentin, 3% water 10% water 12% water 15% water cementum, and alveolar bone.  ◦Cusp Tips/Incisal Edges THICKNESS Thickest ◦CEJ Very Thin  Thick Thin FIGURE 4-26 PERMAR’S ORAL EMBRYOLOGY & MICROSCOPIC ANATOMY, 10TH EDITION  ◦Fused Tissue of REE and Oral Epithelium ◦ Chapter 6 ◦Green-Gray Residue NASMYTH’S MEMBRANE ◦Easily Picks Up Stain from Food Debris ◦Hard to remove EXCEPT by Selective Polishing  ORGANIC SUBSTANCES (4%) ◦1% ◦Protein (not collagen protein-a unique protein similar to keratin) ◦Fine Fibrillar Latticework (around hardened substance is a protein latticework) ◦On And Between Inorganic Substances (Rods, Rod Sheaths And Interrod Substance) ◦3% ◦Water ◦Aids Permeability- ◦Late Bell Stage  Tomes Process (looks similar to an octopus) ◦Secretory surface of the Ameloblast that faces the Dentinoenamel Junction (DEJ) ◦Unlike the process associated with the odontoblast, which is a true cytoplasmic process from a cell body. ◦Tomes process has a six-sided pyramidal shape ◦Responsible for the way the enamel matrix is laid down; thus it is the guiding factor.  INORGANIC SUBSTANCES (96%)** Enamel Rods Basic Unit Of Enamel (Enamel Slightly Curved Prisms) Two Stages Ameloblasts Apposition-formation stage- Deposit partially mineralized Maturation-mineralization Enamel completion stage Figure 12-6A  STAGES Apposition (Deposition) 1. Deposit Organic And Inorganic Matrix 2. Resorb (Remove) Most Of The Organic Substance Maturation (Grow in Size) Tightly Packed Hydroxyapatite Crystals In The In The Form Of Rods-rods expand and become tightly packed together-causing strength  ◦Position ◦Perpendicular To DEJ ◦Origin To Outer Surface Of ENAMEL Enamel RODS ◦Shape ◦Keyhole ◦Stacked In Interlocking Rows ◦Top Toward Occlusal  Figure 4-5 Permar’s Oral Embryology & Microscopic Anatomy, 10 th Edition  ◦Intertwined Rods- smooshed together GNARLED ENAMEL sometimes so much the rods get intertwined ◦Cusp Area-most likely  ◦Filled With Crystalline Calcium Hydroxyapatite ◦Enclosed or surrounded In RODS A Rod Sheath ◦Held Together By Interrod Substance  Figure 4-9 Permar’s Oral Embryology & Microscopic Anatomy, 10 th Edition  ◦Rod ◦Hardest DEGREE OF ◦Inter-rod Substance MINERALIZATION ◦Rod Sheath ◦Least Hard ◦All Very Hard  lines of Retzius ◦Incremental Lines In Mature Enamel ◦Result Of Rhythmic Apposition (Deposition) And Maturation (Mineralization) ◦Cervical Crown ◦Reach The Surface ◦Shallow Depression ◦Mesial To Distal ◦Not On Incisal Or Occlusal  lines of Retzius ◦A microscopic view ◦Resembles the growth rings of a tree. Figure 12-8C  ◦Perikymata ◦Grooves Associated with lines of ◦Imbrication Lines Retzius ◦Ridges in Cervical 1/3 running in a Mesial to Distal Direction  imbrication lines of von Ebner The imbrication lines of von Ebner are incremental lines or bands in a microscopic section of dentin. These lines show the incremental nature of dentin during the apposition stage of tooth development and run at 90 degrees to the dentinal tubules. The imbrication lines of von Ebner that transverse the dentinal tubules in dentin, with their direction noted (arrow). Note the regular pattern of dentin formation Fig. 13.13 Figure 4-2 Permar’s Oral Embryology and Microscopic Anatomy, 10th Edition-(Perikymata)  ENAMEL LAMELLA Hairline Cracks Microscopic Separations Of In Enamel Enamel-geographic faults Causes: Developmental Or Filled With Trauma (Fever or Organic Matrix falling and hitting) May Invade May Influence Dentin Spread Of Decay  Inner End Of “Some” Enamel Rods Located At DEJ ENAMEL TUFTS Unmineralized Looks Like A Bush/brush Rapid Spread Of Decay  Microscopic Appearance of Enamel ◦Microscopic appearance of enamel tufts (white arrow) and enamel lamella (black arrow- looks like a crack) on this transverse section of enamel. Figure 12-11  ◦Odontoblastic Processes that Get Trapped In Enamel-because they have crossed the line of the ENAMEL basement membrane and just SPINDLES stuck ◦DEJ ◦Scalloped Line ◦Spindles Fit Into Concavities  Microscopic Appearance of Enamel ◦Microscopic appearance of enamel spindles (arrows) within the enamel ◦These are odontoblasts near the dentinoenamel junction Figure 12-10  Figure 4-18 Permar’s Oral Embryology and Microscopic Anatomy, 10 th Edition  ◦Mineralization Not Decreased By Any Physiologic Process Within The Tooth ◦Not Withdrawn During PERMEANCE Pregnancy OF ENAMEL ◦Can Be Dissolved In Acid (morning sickness-vomiting is acidic) ◦Enamel Cannot Be Reproduced ◦Ameloblasts Inactive  Curvature Of Rods Increases Resistance To Breakage CLINICAL Arrangement Of Rods IMPORTANCE Influences Path Of Decay Low Mineralized Areas Speeds up spread Of Decay  DECAY PROCESS 1 2 Rod Arrangement Pits And Fissures Contact Area Rods Fan Out Perpendicular To DEJ Small Cavity May Be Decay Spreads Straight To Extensive Beneath The DEJ Opening  Sealants prevent this type of decay Figure 4-5 & 4-28 Permar’s Oral Embryology and Microscopic Anatomy, 10 th Edition AGE RELATED CHANGES Figure 4-25 Permar’s Oral Embryology and Microscopic Anatomy, 10th ◦Attrition Edition ◦Less Permeability-more calcified ◦Darker ◦Reduction Of Caries ◦Increased Surface Fluoride Content ◦Influenced By Environment And Eating Habits Figure 16.17  CHAPTER 13 DENTIN & PULP To accompany Illustrated Dental Embryology, Histology, and Anatomy, 5th Edition Objectives ◦Define and pronounce the key terms in this chapter. ◦Discuss the dentin‑pulp complex and describe the properties of dentin. ◦Describe the processes of the apposition and maturation of dentin. ◦Outline the types of dentin. ◦Indicate and discuss the microscopic features of dentin. ◦Describe the aging of dentin  Dentin-Pulp Complex Dentin Initial Apposition of dentin matrix Chapter Maturation of dentin Outline Components of mature dentin Types of dentin Microscopic features of mature dentin Aging and dentin  ◦Unlike enamel, dentin and pulp cannot be viewed clinically if the teeth and associated periodontium are healthy. Dentin‑Pulp ◦Both dentin and pulp make up the inner portions of the tooth Complex ◦Are not exposed to the oral environment except when certain dental pathology exists. DENTIN  ◦Dentinogenesis is origin and formation of dentin ◦Forms Bulk Of a Tooth ◦Dentin And Pulp DENTIN ◦Interdependence-work together ◦Formed during the Late Bell Stage ◦Starts at the Cusp Tips/Incisal Edges  COMPOSITION ◦70% Inorganic ◦Harder Than Cementum And Bone ◦20% Organic ◦10% Water  20% Organic 30% = & 10% ORGANIC Water MATRIX Collagen Deposited Fibrils And Ground First Substance  70% Hydroxyapatite Deposited On INORGANIC And Around Fibrils Crystallize To Become Hard  Dentin Levels Enamel Dentin Cementum Alveolar Bone ◦The calcium hydroxyapatite found in dentin is ~Mineral 96% 70% 65% 60% similar to that found in a higher levels percentage in enamel and in ~ Organic 1% organic, 20% organic, 23% organic, 25% organic, lower 3% water 10% water 12% water 15% water and percentages in both cementum water and bone tissue levels such as alveolar bone. Denti n ◦Overlying enamel is translucent ◦Dentin gives the white enamel crown its underlying yellow hue (deeper color in permanent teeth) ◦If outer coverings of enamel and cementum are lost… ◦Exposed dentin has various shades of yellow‑white ◦Rougher in surface texture than Enamel. Enamel is much smoother  Dentin ◦Apposition and Maturation Development  REVIEW Dentin Starts At Predentin (Dentoid) DEJ Odontoblasts Organic (Non- (previously Stretchhhhhh Mineralized) known as the and then … is formed Adjacent To The basement Pulp-Always soft membrane)  DENTIN DEVELOPMENT Nanci A. Ten Cate’s Oral Histology, ed 7. Mosby, St. Louis, 2008  ◦3 Distinct Areas ◦Dentinal Tubules ◦Filled With Odontoblastic Processes MICROSCOPIC ◦Peritubular Dentin AREAS ◦Sheath Around Tubules ◦Intertubular Dentin-cement that holds dentin together ◦Bulk Of Dentin ◦Between Tubules MICROSCOPIC APPEARANCE OF DENTIN Nanci A. Ten Cate’s Oral Histology, ed 7. Mosby, St. Louis, 2008  ODONTOBLASTS Processes Surrounded By Move Pulpward, Nucleus Will Dentin Stretching End In Pulp Tubule Formed Odontoblastic Processes Remain In Dentin-hopefully in contact with the DEJ  Figure 5-10 Permar’s Oral Embryology and Microscopic Anatomy, 10 th Edition  ◦“Appear” As Holes Microscopically ◦Lie Very Close Together ◦Perpendicular From DEJ & DCJ To Pulp ◦Straight Shape ◦Crown Cusp Area & Apical 1/2 Of DENTINAL Root TUBULES ◦S-Shaped Curve Shape ◦F,L,M,D Areas Of Crown & Cervical 1/3 Of Root ◦Some Odontoblastic Processes Cross The DEJ and become Enamel Spindles  FIGURES 5-5, 5-6, & 5-7 PERMAR’S ORAL EMBRYOLOGY AND MICROSCOPIC ANATOMY, 10TH EDITION  Primary-starts at DEJ Original Most Dentin-makes up the bulk of the tooth Before Apical Foramen Completely Formed REVIEW Predentin (Dentoid) Proof Of Method Of Deposition Organic Matrix Inorganic Minerals Added Located Next To Pulp  Figure 5-12 Permar’s Oral Embryology and Microscopic Anatomy, 10 th Edition  MANTLE DENTIN 1st to form ◦Layer Of Dentin Right next to the DEJ ◦Fewer Defects ◦First Formed ◦May Contain Korff’s Fibers  KORFF’S FIBERS (von Korff Fibers) ◦Originated When Odontoblasts Differentiated (Bell Stage) ◦Heavy Cork-Screw Shaped Fibers ◦Later “Fray” And Spread Out ◦Located In Mantle Dentin REVIEW Incremental Lines (imbrication lines of von Ebner) Primary Dentin Forms Faster than Secondary Secondary Dentin After Apical Foramen Completed Next to Pulp Tertiary Dentin-not a whole layer-localized where it is needed (Reparative or Reactive Dentin) Localized Response to Trauma Interglobular Dentin Unmineralized Spots Next To Mantle Dentin Caused By Metabolic Disturbance During Formation Possible Lack Of Vitamin D  Found in Peripheral Part of Dentin Beneath Root Cementum- (Root Interglobular interglobular dentin in Dentin the root Next area To Cementum or at the DCJ) Tomes granular layer Unmineralized Spots  Tomes granular layer Figure 13-15 Nanci A. Ten Cate’s Oral Histology, ed 7. Mosby, St. Louis, 2008  ◦Empty Dentinal Tubules DEAD ◦Dead Odontoblast And TRACTS- Odontablastic Processes Disintegrate microscopic holes ◦Increases With Age because of dying odontoblasts  ◦Influences Pattern And Speed Of Caries-acts like a chutes STRUCTURE ◦Bacteria Penetrates Enamel will influence ◦Bacteria Smaller Than Tubules ◦Enter Tubules DECAY ◦Destroys O. Processes ◦Dentin Destroyed Faster Than Enamel-straight shot to the pulp DEFENSIVE REACTIONS Pulp Must Be Vital-if something happens to the pulp the tooth is DEAD Sclerotic Dentin-empty dead tracts that our body puts calcium salts into to block it off May Slow It Down Reparative Dentin-where the invasion occurs Provides Dentin Function Of Pulp Will “Not” Stop Decay  Dentinal Hypersensitivity Dentin is exposed Open dentinal tubules may be painful for the patient Result of  caries  cavity preparation  gingival recession  attrition  Hydrodynamic Theory ◦Stimulation of the exposed dentinal tubules (such as the application of cold water) ◦Causes changes in the dentinal fluid ◦Transmitted to the nerves associated with the cell bodies of the odontoblasts in the pulp tissue Figure 13-9  STRUCTURE / SENSITIVITY Exposed Dentin-initial Overtime Dentin sensitivity Becomes Sclerotic Eating Discomfort Hot, Cold, Sweets, Decreases Acids Prophylaxis Tooth Brushing-scrub brushing  Aging and Dentin ◦Sclerotic Dentin ◦Is a type of Tertiary Dentin ◦Fills Dead Tracts ◦Calcium Salts ◦Dead tracts Increase With Age ◦Locations ◦Attrition, Caries, Tomes’ Layer ◦Protective Function Of Pulp is sclerotic dentin  ◦Tubules ◦Diameter of Tubule Aging and Narrows Dentin ◦Results in Decreased reaction to stimuli-bc less fluid moving back and forth  ◦Internal Resorption or External Resorption-black on radiograph ◦Dentin formed is mostly stable during the life of the Aging and tooth Dentin ◦In a few cases ◦Becomes resorbed in permanent teeth ◦Unknown cause [idiopathic] DENTAL PULP  ◦Pulp ◦Anatomy of pulp Further ◦Microscopic features Chapter of pulp Outline ◦Microscopic zones in pulp ◦Aging and pulp  Develops From Dental Papilla (Central Cells) PULP -soft spot in the middle of tooth Non-mineralized -appears radiolucent on radiograph -Fluid -Intercellular Connective Tissue Substance -Cells  Anatomy of the Pulp ◦Pulp Chamber -Large mass of pulp contained within the tooth ◦The shape of each pulp chamber is individualized for each tooth ◦Two main divisions: ◦coronal pulp ◦radicular pulp (root) Figure 13-16  Coronal Pulp ◦Located in the crown of the tooth ◦Pulp horns ◦Smaller extensions of coronal pulp into the cusps of posterior teeth Figure 13-16  Radicular Pulp (Root Pulp) ◦The portion of the pulp located in the root area of the tooth ◦Also is called the pulp canal by patients ◦Radicular pulp extends from the cervical portion of the tooth Figure 13-16 to the apex of the tooth  Accessory Canals (AKA Lateral Canals because of their location) ◦Accessory canals form when Hertwig’s epithelial root sheath encounters a blood vessel during root formation. ◦Root structure then forms around the vessel, forming the accessory canal. Nanci A. Ten Cate’s Oral Histology, ed 7. Mosby, St. Louis, 2008  Blood Vessels SPECIFIC COMPONENTS Nerves of PULP (Soft) Lymphatics Few Mineralized Structures  ◦Fibroblasts ◦**Most Numerous**- know this ◦Function: ◦Produce Collagen Fibers CELLS OF ◦Throughout Life Of Pulp ◦# of fibroblast decrease With PULP Age ◦Location: ◦Throughout Pulp ◦More Numerous In Cell Rich Zone  UNDIFFERENTIATED MESENCHYMAL CELLS Decrease Located Function With Age Pool Of Near Part Of Cells Capillaries Defense Can become Odontoblasts or Fibroblast  ODONTOBLASTS 2nd Most Location Function Numerous Cells Produce Dentin- In the pulp next secondary or To Dentin tertiary  HISTOCYTES (act like Pac Man) 1 2 3 Type Of Defense Cell Pulp Maintenance Macrophage-eats foreign objects Ability To Ingest Foreign Matter (Microorganisms)  ◦Blood Stream cells ◦Red Blood Cells-vascular ◦White Blood Cells- usually low unless they are triggered by inflammation or OTHER infection CELLS ◦Lymphocytes ◦Function ◦Immune System ◦Fight Infection ◦Numbers Increase Denticles (Pulp Stones) Mineralized Objects- can be mineralized masses of dentin that are unattached to the pulpal wall 80% In Older People Increase With Age Non-significant May Interfere With Endodontics Opaque On X-ray Some Scattered Spicules  Viewed Microscopically Four zones ZONES OF THE PULP Odontoblastic zone Cell-free zone Cell-rich zone Pulpal core- seen in Young Healthy Pulp FIGURE 13.18  ODONTOBLASTIC ZONE Is Next To Predentin Layer Of Dentin Odontoblast Cell Bodies lie here Odontoblasts Capable of Forming Secondary & Tertiary Dentin along Outer Pulp Wall Interprets External Stimuli because they have Contact Nerve Endings  (Weil’s Zone) Next To Odontoblasts CELL FREE Fewer Cells ZONE It has Nerve & Capillary Plexus there (Location) Function  Located inward from Cell-free zone Many Cells CELL-RICH ZONE Mostly Fibroblasts And Undifferentiated Mesenchymal Cells Function Reservoir Of Cells  PULPAL CORE Many Cells & Innermost zone Extensive Vascular Supply  Four Functions of the pulp Formative Sensory Nutritive Defensive / Protective  Four Functions ◦Formative ◦ Defensive Ways ◦ Dentin ◦ 1) Inflammatory ◦Sensory ◦ Pulp Damage ◦ Nerve Fibers end in odontoblasts ◦ Microorganisms ◦ Cytoplasm in dentin help maintain ◦ Restorative Materials dentin ◦ Defense Cells ◦ Sensitive- dentin ◦ Histocytes Attempt To Control Damage to the Pulp Has Excellent Regenerative ◦ All receptors are for pain Properties ◦Nutritive ◦ Pulp Can Heal Mild Inflammation ◦ Receives Nutrients From Blood ◦ 2) Change Dentin ◦ Nourishes Dentin Through Odontoblasts ◦ Sclerosis and Processes ◦ Barrier to Decay ◦ 3) Reparative/Secondary Dentin ◦ Barrier Between Pulp And External Irritation  ◦Tooth Can Function Without A Pulp (Root Canal Therapy or Treatment) ◦Causes Brittle Enamel IMPORTANCE ◦Crown is necessary OF PULP ◦Cementum Not Affected ◦Cannot Reproduce dentin once the pulp is dead ◦Tertiary (Reparative) Or Sclerotic Dentin  AGED RELATED CHANGES Normal Fewer Cells Smaller Pulp Cavity Decrease in Intercellular Decrease Blood And Substance & Increase Receded Pulp Horns Nerve Supply in Collagen Fibers (More Fibrotic)  AGE RELATED CHANGES ◦Reduced Sensitivity ◦Obliterated Apical Foramen will cause Blockage of Blood Vessels and Pulp Necrosis or Tooth Death ◦More Abnormalities ◦Mineralization’s (pulp stones) ◦None Alter Function Except ◦Reduced Response To Injury and the Ability To Repair Itself