NEET MDS Synopsis
Other Antidepressants
Pharmacology
Serotonin-norepinephrine reuptake inhibitors(SNRIs)
e.g. venlafaxine and duloxetine
- Inhibit the reuptake of both 5-HT and norepinephrine
- Has a more favourable adverse effect profile than TCAs
Norepinephrine reuptake inhibitor
e.g. bupropion, reboxetine
Monoamine receptor antagonists
e.g. mirtazapine, trazodone, mianserin
Nutrition and tooth development
Dental Anatomy
Nutrition and tooth development
As in other aspects of human growth and development, nutrition has an effect on the developing tooth. Essential nutrients for a healthy tooth include calcium, phosphorus, fluoride, and vitamins A, C, and D. Calcium and phosphorus are needed to properly form the hydroxyapatite crystals, and their levels in the blood are maintained by Vitamin D. Vitamin A is necessary for the formation of keratin, as Vitamin C is for collagen. Fluoride is incorporated into the hydroxyapatite crystal of a developing tooth and makes it more resistant to demineralization and subsequent decay.
Deficiencies of these nutrients can have a wide range of effects on tooth development. In situations where calcium, phosphorus, and vitamin D are deficient, the hard structures of a tooth may be less mineralized. A lack of vitamin A can cause a reduction in the amount of enamel formation. Fluoride deficency causes increased demineralization when the tooth is exposed to an acidic environment, and also delays remineralization. Furthermore, an excess of fluoride while a tooth is in development can lead to a condition known as fluorosis.
Soft Oral Tissues
Dental Anatomy
Soft Oral Tissues
Oral Mucosa
The oral mucosa consists mainly of two types of tissues: the oral epithelium, which consists of stratified, squamous epithelium, and the underlying connective tissue layer, known as the lamina propria. There are three variations of oral mucosa.
A. Oral epithelium
1. Consists of stratified, squamous epithelium.
2. Four layers (Note: Cells mature as they progress from the deepest [basal] layer to the most superficial [cornified] layer) a. Basal layer (stratum germinativum or basale)
(1) A single layer of cuboidal or columnar cells overlying the lamina propria.
(2) Contains progenitor cells and thus provides cells to the epithelial layers above.
(3) Site of cell division (mitosis).
b. Prickle cell layer (stratum spinosum)
(1) Consists of several layers of larger, ovoid-shaped cells.
c. Granular layer (stratum granulosum)
(1) Cells appear larger and flattened.
(2) Granules (known as keratohyaline granules) are present in the cells.
(3) This layer is absent in nonkeratinized epithelium.
d. Cornified layer (stratum corneum, keratin, or horny layer)
(1) In keratinized epithelium:
(a) Orthokeratinized epithelium the squamous cells on the surface appear flat and contain keratin. They have no nuclei present.
(b) Parakeratinized epithelium the squamous cells appear flat and contain keratin; nuclei are present within the cells.
(2) In parakeratinized epithelium, both squamous cells without nuclei and cells with shriveled (pyknotic) nuclei are present.
(3) In nonkeratinized epithelium, the cells appear slightly flattened and contain nuclei.
B. Lamina propria
1. Consists of type I and III collagen, elastic fibers, and ground substance. It also contains many cell types, including fibroblasts, endothelial cells, immune cells, and a rich vascular and nerve supply.
2. Two layers:
a. Superficial, papillary layer
(1) Located around and between the epithelial ridges.
(2) Collagen fibers are thin and loosely arranged.
b. Reticular layer
(1) Located beneath the papillary layer.
(2) Collagen fibers are organized in thick, parallel bundles.
C. Types of oral mucosa
1. Masticatory mucosa
a. Found in areas that have to withstand compressive and shear forces.
b. Clinically, it has a rubbery, firm texture.
c. Regions: gingiva, hard palate.
2. Lining mucosa
a. Found in areas that are exposed to high levels of friction, but must also be mobile and distensible.
b. Clinically, it has a softer, more elastic texture.
c. Regions: alveolar mucosa, buccal mucosa, lips, floor of the mouth, ventral side of the tongue, and soft palate.
3. Specialized mucosa
a. Similar to masticatory mucosa, specialized mucosa is able to tolerate high compressive
and shear forces; however, it is unique in that it forms lingual papillae.
b. Region: dorsum of the tongue.
D. Submucosa
1. The connective tissue found beneath the mucosa . It contains blood vessels and nerves and may also contain fatty tissue and minor salivary glands.
2. Submucosa is not present in all regions of the oral cavity, such as attached gingiva, the tongue, and hard palate. Its presence tends to increase the mobility of the tissue overlying it.
E. Gingiva
1. The portion of oral mucosa that attaches to the teeth and alveolar bone.
2. There are two types of gingiva: attached and free gingiva. The boundary at which they meet is known as the free gingival groove .
a. Attached gingiva
(1) Directly binds to the alveolar bone and tooth.
(2) It extends from the free gingival groove to the mucogingival junction.
b. Free gingiva
(1) Coronal to the attached gingiva, it is not bound to any hard tissue.
(2) It extends from the gingival margin to the free gingival groove.
c. Together, the free and attached gingiva form the interdental papilla.
.F. Alveolar mucosa
1. The tissue just apical to the attached gingiva.
2. The alveolar mucosa and attached gingiva meet at the mucogingival junction .
G. Junctional epithelium
1. Area where the oral mucosa attaches to the tooth, forming the principal seal between the oral cavity and underlying tissues.
2. Is unique in that it consists of two basal lamina, an internal and external . The internal basal lamina, along with hemidesmosomes, comprises the attachment apparatus (the epithelial attachment). This serves to attach the epithelium directly to the tooth.
3. Histologically, it remains as immature, poorly differentiated tissue. This allows it to maintain its ability to develop hemidesmosomal attachments.
4. Has the highest rate of cell turnover of any oral mucosal tissue.
H. Interdental papilla (interdental gingiva)
1. Occupies the interproximal space between two teeth. It is formed by free and attached gingiva.
2. Functions to prevent food from entering the (interproximal) area beneath the contact point of two adjacent teeth. It therefore plays an important role in maintaining the health of the gingiva.
3. Col
a. If the interdental papilla is cross-sectioned in a buccolingual plane, it would show two peaks (buccal and lingual) with a dip between them, known as the col or interdental col. This depression occurs around the contact point of the two adjacent teeth.
b. Histologically, col epithelium is the same as junctional epithelium
Classification of Local anesthetics
Pharmacology
Classification
I) Esters
1. Formed from an aromatic acid and an amino alcohol.
2. Examples of ester type local anesthetics:
Procaine
Chloroprocaine
Tetracaine
Cocaine
Benzocaine- topical applications only
2) Amides
1. Formed from an aromatic amine and an amino acid.
2. Examples of amide type local anesthetics:
Articaine
Mepivacaine
Bupivacaine
Prilocaine
Etidocaine
Ropivacaine
Lidocaine
Blood Disorder Drugs
Pharmacology
COAGULANTS
An agent that produces coagulation (Coagulation is a complex process by which blood forms clots).
ANTICOAGULANTS
An anticoagulant is a substance that prevents coagulation; that is, it stops blood from clotting.
Anticoagulants:
Calcium Chelators (sodium citrate, EDTA)
Heparin
Dalteparin Sodium (Fragmin) -Low molecular-weight heparin
Enoxaparin - Low molecular-weight heparin
Tinzaparin Sodium - Low molecular-weight heparin
Warfarin
Lepirudin - recombinant form of the natural anticoagulant hirudin: potent and specific Thrombin inhibitor
Bivalirudin - analog of hirudin: potent and specific Thrombin inhibitor
Procoagulants:
Desmopressin acetate
Antiplatelet Drugs:
Acetylsalicylic Acid, Ticlopidine, Sulfinpyrazone, Abciximab , Clopidogrel bisulfate
Fibrinolytic Drugs:
Tissue Plasminogen Activator (t-PA, Activase), Streptokinase (Streptase),
Anistreplase, Urokinase
Antagonists:
Protamine sulfate, Aminocaproic acid
Pharmacological agents used to treat blood coagulation disorders fall in to three major categories:
1. Anticoagulants: Substances that prevent the synthesis of a fibrin network which inhibits coagulation and the formation of arterial thrombi and thromboembolic clots.
2. Antiplatelet agents: Substances that reduce the adhesion and aggregation of platelets.
3. Fibrinolytic agents: Substances that promote the destruction of already formed blood clots or thrombi by disrupting the fibrin mesh.
Serotonin or 5-hydroxytryptamine
Pharmacology
Serotonin or 5-hydroxytryptamine (5-HT)
It is a neurotransmitter, widely distributed in the CNS, beginning in the midbrain and projecting into thalamus, hypothalamus, cerebral cortex, and spinal cord. CNS serotonin is usually an inhibitory neurotransmitter and is associated with mood, the sleep-wake cycle.
Serotonin is thought to produce sleep by inhibiting CNS activity.
In the blood, 5-HT is present in high concentration in platelets (regulator of platelets function) and also high concentration in intestine
Pharmacological effects:
Smooth muscles. 5-HT stimulates the G.I smooth muscle; it increases the peristaltic movement of intestine.
Serotonin contracts the smooth muscle of bronchi;
Blood vessels. If serotonin is injected i.v, the blood pressure usually first rises, because of the contraction of large vessels and then falls because of arteriolar dilatation. Serotonin causes aggregation of platelets.
Specific agonists
- Sumatriptan a selective 5-HT1D used in treatment of acute migraine.
- Buspirone a selective 5-HT1A used in anxiety.
- Ergotamine is a partial agonist used in migraine. It acts on 5-HT1A receptor.
Nonspecific 5-HT receptor agonist
o Dexfenfluramine used as appetite suppressant.
Specific antagonists
o Spiperone (acts on 1A receptor) and
o Methiothepin (acts on 1A, 1B, 1D receptors)
Genioglossus Muscle
AnatomyGenioglossus Muscle
Origin: Mental spine of the mandible.
Insertion: Dorsum of the tongue and hyoid bone.
Nerve Supply: Hypoglossal nerve (CN XII).
Arterial Supply: Sublingual and submental arteries.
Action: Depresses and protrudes the tongue.
FAT-SOLUBLE VITAMINS
Biochemistry
FAT-SOLUBLE VITAMINS
The fat-soluble vitamins, A, D, E, and K, are stored in the body for long periods of time and generally pose a greater risk for toxicity when consumed in excess than water-soluble vitamins.
VITAMIN A: RETINOL
Vitamin A, also called retinol, has many functions in the body. In addition to helping the eyes adjust to light changes, vitamin A plays an important role in bone growth, tooth development, reproduction, cell division, gene expression, and regulation of the immune system.
The skin, eyes, and mucous membranes of the mouth, nose, throat and lungs depend on vitamin A to remain moist. Vitamin A is also an important antioxidant that may play a role in the prevention of certain cancers.
One RAE equals 1 mcg of retinol or 12 mcg of beta-carotene. The Recommended Dietary Allowance (RDA) for vitamin A is 900 mcg/ day for adult males and 700 mcg/ day for adult females.
Vitamin A Deficiency
Vitamin A deficiency is rare, but the disease that results is known as xerophthalmia.
Other signs of possible vitamin A deficiency include decreased resistance to infections, faulty tooth development, and slower bone growth.
Vitamin A toxicity The Tolerable Upper Intake Level (UL) for adults is 3,000 mcg RAE.
VITAMIN D
Vitamin D plays a critical role in the body’s use of calcium and phosphorous. It works by increasing the amount of calcium absorbed from the small intestine, helping to form and maintain bones.
Vitamin D benefits the body by playing a role in immunity and controlling cell growth. Children especially need adequate amounts of vitamin D to develop strong bones and healthy teeth.
RDA From 12 months to age fifty, the RDA is set at 15 mcg.
20 mcg of cholecalciferol equals 800 International Units (IU), which is the recommendation for maintenance of healthy bone for adults over fifty.
Vitamin D Deficiency
Symptoms of vitamin D deficiency in growing children include rickets (long, soft bowed legs) and flattening of the back of the skull. Vitamin D deficiency in adults may result in osteomalacia (muscle and bone weakness), and osteoporosis (loss of bone mass).
Vitamin D toxicity
The Tolerable Upper Intake Level (UL) for vitamin D is set at 100 mcg for people 9 years of age and older. High doses of vitamin D supplements coupled with large amounts of fortified foods may cause accumulations in the liver and produce signs of poisoning.
VITAMIN E: TOCOPHEROL
Vitamin E benefits the body by acting as an antioxidant, and protecting vitamins A and C, red blood cells, and essential fatty acids from destruction.
RDA One milligram of alpha-tocopherol equals to 1.5 International Units (IU). RDA guidelines state that males and females over the age of 14 should receive 15 mcg of alpha-tocopherol per day.
Vitamin E Deficiency Vitamin E deficiency is rare. Cases of vitamin E deficiency usually only occur in premature infants and in those unable to absorb fats.
VITAMIN K
Vitamin K is naturally produced by the bacteria in the intestines, and plays an essential role in normal blood clotting, promoting bone health, and helping to produce proteins for blood, bones, and kidneys.
RDA
Males and females age 14 - 18: 75 mcg/day; Males and females age 19 and older: 90 mcg/day
Vitamin K Deficiency
Hemorrhage can occur due to sufficient amounts of vitamin K.
Vitamin K deficiency may appear in infants or in people who take anticoagulants, such as Coumadin (warfarin), or antibiotic drugs.
Newborn babies lack the intestinal bacteria to produce vitamin K and need a supplement for the first week.