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1. UNIVERSITY OF BURAO DEPARTMENT OF DENTAL 🦷

2. PRESENTATION GROUP 1

3. CHAPTER Enamels 🦷

4. CHAPTER : ENAMELS. 🦷 🦷 Definition : Enamel is the outermost layer of the tooth, It’s the hardest and most mineralized substance in the human body . Enamel

5. Composition of Enamels 🦷 Enamel : is made up of about 96% inorganic minerals , primarily hydroxyapatite (a crystalline form of calcium phosphate). The remaining 4% is composed of water and a small amount of organic material This high mineral content gives enamel its extreme hardness but also makes it brittle and susceptible to cracking if overstressed. Component Percentage Function Minerals (Inorganic) 96% Gives hardness and strength Organic Matrix (Proteins) 1-2% Helps in enamel formation Water 2-4% Allows ion transport and exchange

6. ✅ Structure Enamel 🦷 All the structures of enamel include: ✅ Enamel Rods (Prisms) ✅ Interrod Enamel ✅ Enamel Lamellae ✅ Enamel Tufts ✅ Enamel Spindles ✅ Surface Enamel ( Aprismatic layer )

7. ✅ Structure Enamel 🦷 1️⃣ Enamel Rods (Prisms) This is the main component of enamel. They are shaped like tiny tubes or straight fibers that start from the dentin and extend to the outer surface of the tooth. Each tooth contains millions of enamel rods Each rod is made up of tightly packed hydroxyapatite crystals The rods can twist and turn (this is what forms "Hunter-Schreger bands" under the microscope)

8. 2️⃣ Interrod Enamel This is the enamel that surrounds the rods. Although made of the same hydroxyapatite crystals, their direction is different from that of the rods. It works like a "glue" that binds the enamel rods together, giving the enamel its great strength.

9. These are thin lines or small cracks that run vertically from the enamel surface down towards the middle. They are seen more clearly when enamel is slightly weakened, but even healthy enamel can have them. Lamellae can be weak points where bacteria might penetrate if proper care isn’t taken. 3️⃣ Enamel Lamellae

10. These are small grass-like or tuft structures that start at the junction between the dentin and the enamel (usually near the cusp of the tooth). They contain more organic material and less mineral. They help absorb stress and prevent the enamel from cracking under pressure. 4️⃣ Enamel Tufts.

11. 5️⃣ Enamel Spindles. These are small thread-like structures that come from the dentin and extend into the enamel. They are formed when dentin tubules accidentally grow a little into the enamel during tooth development. They may play a role in transmitting sensation between enamel and dentin .

12. This is the very top layer of enamel on the tooth surface. Unlike the inner parts, it does not show visible rods — the crystals here are aligned more uniformly. This layer is extra hard and protects the tooth against acids and physical damage. 6️⃣ Surface Enamel ( Aprismatic Enamel).

13. ✅ Functions of Tooth Enamel 🦷 1️⃣ Protection of Inner Tooth Structures. The primary function of enamel is to protect the dentin and pulp inside the tooth. It acts as a hard barrier against Bacteria Acids (from foods and drinks) Physical forces (like chewing and biting) Without enamel, the soft inner tissues would be exposed, leading to pain, infection, and damage. 2️⃣ Resistance to Wear and Tear (Mechanical Function) Enamel is the hardest substance in the human body, making it perfect for enduring: Chewing forces Grinding (mastication) Biting pressure It helps distribute the pressure evenly across the tooth and into the supporting bone structure.

14. 3️⃣ Prevention of Tooth Sensitivity Underneath enamel lies the dentin , which contains tiny tubules connected to the nerve-rich pulp. Enamel acts like an insulating layer , blocking hot, cold, sweet, or acidic stimuli from reaching the nerves When enamel wears down, people often experience tooth sensitivity . 4️⃣ Defense Against Decay (Caries Protection) Enamel forms the first line of defense against tooth decay . By being mineral-rich and smooth, it resists the attachment and penetration of harmful bacteria. Fluoride strengthens enamel and enhances this defensive function by making it more resistant to acid attacks.

15. 5️⃣ Aesthetic Function (Appearance). Enamel gives teeth their white, shiny, and glossy appearance . Light reflects off enamel, giving teeth their natural brightness. The thickness and quality of enamel influence the color of the tooth — thinner enamel may reveal more of the yellowish dentin underneath. 6️⃣ Maintains Tooth Shape and Structure Enamel preserves the proper shape, height, and contour of the tooth. This is important for: Proper chewing function. Correct bite alignment (occlusion). Preventing shifting of teeth over time.

16. 7️⃣ Facilitates Speech. The structure and integrity of enamel-covered teeth help in forming certain sounds and speech patterns . Damage or loss of enamel (and teeth) can affect pronunciation and clarity of speech. 8️⃣ Supports Facial Structure Healthy teeth covered with enamel contribute to maintaining the natural shape of the face and jaw. Tooth wear or loss (due to enamel damage) can lead to facial collapse or sagging over time.

17. 🦷 ✅ Clinical Conditions of Tooth Enamel. 1️⃣ Enamel Caries (Tooth Decay). Caused by acids from bacteria dissolving the enamel crystals. Starts as white spots ➔ then progresses to brown holes or cavities. If untreated, it spreads to dentin and pulp, causing pain and infection . 2️⃣ Enamel Erosion. Loss of enamel due to acids not caused by bacteria. Common causes: Acidic foods/drinks (sodas, citrus). Stomach acid (reflux, vomiting). Leads to thinning enamel, yellowish teeth, and sensitivity .

18. 3️⃣ Enamel Attrition. Physical wearing down of enamel due to tooth grinding or heavy chewing. Causes flat, worn-down biting surfaces. Common in people with bruxism (teeth grinding habit). 4️⃣ Enamel Abrasion. Mechanical wear from external factors. Causes: Hard tooth brushing. Abrasive toothpaste. Habitual biting on objects (pens, nails). Leads to notches at the neck of the tooth (near the gum line).

19. 5️⃣ Enamel Hypoplasia. A developmental defect where enamel is thin or incomplete. Causes: Childhood illnesses. Malnutrition. Trauma during tooth formation. Results in pits, grooves, or missing areas of enamel. 6️⃣ Amelogenesis Imperfecta. A rare genetic disorder affecting enamel formation. Leads to: Weak, soft enamel. Discolored, pitted, or rough teeth. High risk of decay and sensitivity.

20. 📝 ✅ Table of Tooth Enamel Conditions. Condition Name Cause Symptoms/Signs Enamel Caries (Decay) Acid from bacteria White spots ➔ brown holes (cavities) Erosion (Acid Wear) Acid from food/stomach Yellowish teeth, sensitivity Attrition (Tooth Wear) Tooth grinding, heavy biting Flat, worn-down tooth surfaces Abrasion (Mechanical Wear) Hard brushing, biting objects Notches at the neck of the tooth Hypoplasia (Underdevelopment) Childhood illness, malnutrition, trauma Lines, pits, missing enamel areas Amelogenesis Imperfecta Genetic disorder Weak enamel, discoloration, pits

21. 📝 ✅ Tooth Enamel: Protections, Problems, and Treatments ✔️ Protection ❌ Problem if Damaged 🩺 Treatment Shields against bacteria Tooth decay (caries) Fillings, fluoride treatment Prevents tooth sensitivity Pain with cold, hot, sweet foods Desensitizing agents, fillings Maintains white, shiny appearance Discoloration, yellow/brown stains Whitening, veneers, crowns Resists acid and physical wear Erosion, attrition, abrasion Dental restorations, crowns Cannot regenerate (irreversible) Permanent loss if damaged Requires dental intervention 🔑 Key Points: 👉 Once enamel is lost, it does not grow back — only dental treatments can repair the damage. 👉 Daily care (brushing, avoiding acids, dental check-ups) is the best way to protect enamel.

22. 🔹 Unique Features of Tooth Enamel 🦷 1️⃣ Hardest Tissue in the Human Body. Enamel is harder than bone or dentin because it has the highest mineral content (about 96% hydroxyapatite). This makes it very strong for chewing and biting. 3️⃣ No Nerves or Blood Vessels. Enamel is completely non-living tissue. That’s why it doesn’t feel pain directly (pain comes when dentin is exposed). 4️⃣ Cannot Regenerate or Repair Itself Once enamel is lost, it does not grow back naturally. Dental treatments (fillings, crowns) are the only way to restore it .

23. 5️⃣ Formed Only Once in Life. Enamel forms during tooth development and never forms again. If damaged later in life, no new enamel is produced. 8️⃣ Resistant to Bacteria, But Vulnerable to Acid. Enamel resists bacterial invasion but can be dissolved by acids (from food or bacteria). That’s why fluoride is used to strengthen it.