NEET MDS Synopsis
Calcium Channel Blocking Agents- Antianginal Drugs
Pharmacology
Calcium Channel Blocking Agents
• Act on contractile and conductive tissues of the heart and on vascular smooth muscles
• Prevent movement of extracellular calcium into the cell
– Coronary and peripheral arteries dilate
– Myocardial contractility decreases
– Depress conduction system
Therapeutic Actions
• Inhibit movement of calcium ions across the membranes of myocardial and arterial muscle cells. Altering the action potential and blocking muscle cell contraction
• Depress myocardial contractility
• Slow cardiac impulse formation in the conductive tissues
• Cause a fall in BP
Amelogenesis and Enamel
Dental Anatomy
Amelogenesis and Enamel
Enamel is highly mineralized: 85% hydroxyapatite crystals
Enamel formation is a two-step process
The first step produces partially mineralized enamel: 30% (secretory)
The second step: Influx of minerals, removal of water and organic matrix (maturative)
Again, dentin is the prerequisite of enamel formation (reciprocal induction)
Stratum intermedium: high alkaline phosphatase activity
Differentiation of ameloblasts: Increase in glycogen contents
Formation of the enamel matrix
Enamel proteins, enzymes, metalloproteinases, phosphatases, etc.
Enamel proteins: amelogenins (90%), enamelin, tuftelin, and amelin
Amelogenins: bulk of organic matrix
Tuftelin: secreted at the early stages of amelogenesis (area of the DE junction)
Enamelin: binds to mineral
Amelin
Mineralization of enamel
No matrix vesicles
Immediate formation of crystallites
Intermingling of enamel crystallites with dentin
"Soft" enamel is formed
Histologic changes
Differentiation of inner enamel epithelium cells. They become ameloblasts
Tomes' processes: saw-toothed appearance
Collapse of dental organ
Formation of the reduced enamel epithelium
Hard tissue formation (Amelogenesis )
Enamel formation is called amelogenesis and occurs in the crown stage of tooth development. "Reciprocal induction" governs the relationship between the formation of dentin and enamel; dentin formation must always occur before enamel formation. Generally, enamel formation occurs in two stages: the secretory and maturation stages. Proteins and an organic matrix form a partially mineralized enamel in the secretory stage; the maturation stage completes enamel mineralization.
In the secretory stage, ameloblasts release enamel proteins that contribute to the enamel matrix, which is then partially mineralized by the enzyme alkaline phosphatase. The appearance of this mineralized tissue, which occurs usually around the third or fourth month of pregnancy, marks the first appearance of enamel in the body. Ameloblasts deposit enamel at the location of what become cusps of teeth alongside dentin. Enamel formation then continues outward, away from the center of the tooth.
In the maturation stage, the ameloblasts transport some of the substances used in enamel formation out of the enamel. Thus, the function of ameloblasts changes from enamel production, as occurs in the secretory stage, to transportation of substances. Most of the materials transported by ameloblasts in this stage are proteins used to complete mineralization. The important proteins involved are amelogenins, ameloblastins, enamelins, and tuftelins. By the end of this stage, the enamel has completed its mineralization.
Nerves of the Tongue
Anatomy
Anterior 2/3 of tongue
Posterior 1/3 of tongue
Motor Innervation
All muscles by hypoglossal nerve (CN XII) except palatoglossus muscle (by the pharyngeal plexus)
General Sensory Innervation
Lingual nerve (branch of mandibular nerve CN V3)
Glossopharyngeal nerve (CN IX)
Special Sensory Innervation
Chorda tympani nerve (branch of facial nerve)
Glossopharyngeal nerve (CN IX)
Dimensions of Toothbrushes
PeriodontologyDimensions of Toothbrushes
Toothbrushes play a crucial role in maintaining oral hygiene, and their
design can significantly impact their effectiveness. The American Dental
Association (ADA) has established guidelines for the dimensions and
characteristics of acceptable toothbrushes. This lecture will outline these
specifications and discuss their implications for dental health.
Acceptable Dimensions of Toothbrushes
Brushing Surface Dimensions:
Length:
Acceptable brushing surfaces should measure between 1 to
1.25 inches (25.4 to 31.8 mm) long.
Width:
The width of the brushing surface should range from 5/16
to 3/8 inch (7.9 to 9.5 mm).
Rows of Bristles:
Toothbrushes should have 2 to 4 rows of bristles to
effectively clean the teeth and gums.
Tufts per Row:
Each row should contain 5 to 12 tufts of
bristles, allowing for adequate coverage and cleaning ability.
Filament Diameter:
The diameter of the bristles can vary, affecting the stiffness and
cleaning effectiveness:
Soft Filaments:
Diameter of 0.2 mm (0.007 inches). Ideal
for sensitive gums and children.
Medium Filaments:
Diameter of 0.3 mm (0.012 inches). Suitable
for most adults.
Hard Filaments:
Diameter of 0.4 mm (0.014 inches).
Generally not recommended for daily use as they can be abrasive
to the gums and enamel.
Filament Stiffness:
The stiffness of the bristles is determined by the diameter relative
to the length of the filament. Thicker filaments tend to be stiffer,
which can affect the brushing technique and comfort.
Special Considerations for Children's Toothbrushes
Size:
Children's toothbrushes are designed to be smaller to accommodate
their smaller mouths and teeth.
Bristle Thickness:
The bristles are thinner, measuring 0.005 inches (0.1
mm) in diameter, making them gentler on sensitive gums.
Bristle Length:
The bristles are shorter, typically around 0.344 inches (8.7
mm), to ensure effective cleaning without causing discomfort.
Clinical Implications
Choosing the Right Toothbrush:
Dental professionals should guide patients in selecting toothbrushes
that meet ADA specifications to ensure effective plaque removal and gum
protection.
Emphasizing the importance of using soft or medium bristles can help
prevent gum recession and enamel wear.
Education on Brushing Technique:
Proper brushing technique is as important as the toothbrush itself.
Patients should be educated on how to use their toothbrush effectively,
regardless of the type they choose.
Regular Replacement:
Patients should be advised to replace their toothbrush every 3
to 4 months or sooner if the bristles become frayed. This
ensures optimal cleaning effectiveness.
Special Considerations for Children:
Parents should be encouraged to choose appropriately sized
toothbrushes for their children and to supervise brushing to ensure
proper technique and effectiveness.
Primary Retention Form
Conservative DentistryPrimary Retention Form in Dental Restorations
Primary retention form refers to the geometric shape or design of a prepared
cavity that helps resist the displacement or removal of a restoration due to
tipping or lifting forces. Understanding the primary retention form is crucial
for ensuring the longevity and stability of various types of dental
restorations. Below is an overview of primary retention forms for different
types of restorations.
1. Amalgam Restorations
A. Class I & II Restorations
Primary Retention Form:
Occlusally Converging External Walls: The walls of
the cavity preparation converge towards the occlusal surface, which
helps resist displacement.
Occlusal Dovetail: In Class II restorations, an
occlusal dovetail is often included to enhance retention by providing
additional resistance to displacement.
B. Class III & V Restorations
Primary Retention Form:
Diverging External Walls: The external walls
diverge outward, which can reduce retention.
Retention Grooves or Coves: These features are
added to enhance retention by providing mechanical interlocking and
resistance to displacement.
2. Composite Restorations
A. Primary Retention Form
Mechanical Bond:
Acid Etching: The enamel and dentin surfaces are
etched to create a roughened surface that enhances mechanical retention.
Dentin Bonding Agents: These agents infiltrate the
demineralized dentin and create a hybrid layer, providing a strong bond
between the composite material and the tooth structure.
3. Cast Metal Inlays
A. Primary Retention Form
Parallel Longitudinal Walls: The cavity preparation
features parallel walls that help resist displacement.
Small Angle of Divergence: A divergence of 2-5 degrees
may be used to facilitate the seating of the inlay while still providing
adequate retention.
4. Additional Considerations
A. Occlusal Dovetail and Secondary Retention Grooves
Function: These features aid in preventing the proximal
displacement of restorations by occlusal forces, enhancing the overall
retention of the restoration.
B. Converging Axial Walls
Function: Converging axial walls help prevent occlusal
displacement of the restoration, ensuring that the restoration remains
securely in place during function.
Emergency conditions in Dental Clinics p2
Oral Medicine
Emergency conditions in Dental Clinics
Hypoadrenalism - Usually the patient is known to have Addison's disease or to be taking steroids long term and has forgotten to take the tablets.
Signs and symptoms
• Pallor
• Confusion
• Rapid weak pulse.
Treatment:
Give oxygen
Give 200 mg hydrocortisone sodium succinate by slow i.v. injection.
Give steroid replacement
Determining and managing underlying cause once the crisis over.
If required:
• Transfer to Emergeny hostpital
• Fluids and further hydrocortisone, both i.v.
Acute asthma - Exposure to antigen but precipitated by many factors including anxiety.
Signs and symptoms
• Persistent shortness of breath poorly relieved by bronchodilators
• Restlessness and exhaustion
• Tachycardia greater than 110 beats/min and low peak expiratory flow
• Respirations may be so shallow in severe cases that wheezing is absent.
Treatment
Excluded respiratory obstruction
Sit the patient up
Give oxygen
Salbutamol (Ventolin) via a nebuliser (2.5-5 mg of 1 mg/ml nebuliser solution) or via a large-volume spacer (two puffs of a metered dose inhaler 10-20 times: one puff every 30 seconds up to 10 puffs for a child)
Reassure and allow home if recovered.
• Bronchodilatation.
If Major Problem recommend to hospital Emergeny
• Hydrocortisone sodium succinate i.v.: adults 200 mg; child 100 mg
• Add ipratropium 0.5 mg to nebulised salbutamol
• Aminophylline slow i.v. injection of 250 mg in 10 ml over at least 20 minutes: monitor or keep finger on pulse during injection.
Caution in epilepsy: rapid injection of aminophylline may cause arrhythmias and convulsions.
Caution in patients already receiving theophylline: arrhythmias or convulsions may occur.
Anaphylactic shock
Signs and symptoms
• Paraesthesia, flushing and swelling of face, especially eyelids and lips (Fig. 13)
• generalised urticaria, especially hands and feet
• wheezing and difficulty in breathing
• rapid weak pulse.
These may develop over 15 to 30 minutes following the oral administration of a drug or rapidly over a few minutes following i.v. drug administration.
Treatment
Lay patient flat and raise feet
Give oxygen
Give 0.5 ml epinephrine (adrenaline) 1 mg/ml (1 in
1000) intramuscular
— 0.25 ml for 6-12 years
— 0.12 ml for 6 months to 6 years
repeated every 10 min until improvement.
Requires prompt energetic treatment of
• laryngeal oedema
• bronchospasm
• hypotension.
• Chlorphenamine (chlorpheniramine) 10 mg in 1 ml intramuscular or slow i.v. injection
• Hydrocortisone sodium succinate 200 mg by slow i.v. injection: valuable as action persists after that of adrenaline has worn off
• Fluids i.v. (colloids) infused rapidly if shock not responding quickly to adrenaline.
Stroke - Stroke results from either cerebral haemorrhage or cerebral ischaemia.
Signs and symptoms
• Confusion followed by signs and symptoms of focal brain damage
• Hemiplegia or quadriplegia
• Sensory loss
• Dysphasia
• Locked-in syndrome (aware, but unable to respond).
Treatment
Maintain and transfer for further investigation.
Benzodiazepine overdose - Overdose can result from a large or a fast dose of benzodiazepine or can occur in a sensitive patient.
Signs and symptoms
• Deeply sedated
• Severe respiratory depression.
Treatment
Flumazenil (Annexate) 200 mg over 15 seconds as 100 mg/ml i.v. followed by 100 mg every 1 minute up to maximum of 1 mg Maintain airway with head tilt/chin lift
Give oxygen.
Treatment
The action of the benzodiazepine is reversed with the specific antagonist.
Angina and myocardial infarction
Signs and symptoms
• Sudden onset of severe crushing pain across front of chest, which may radiate towards the shoulder and down the left arm or into the neck and jaw; pain from angina usually radiates down left arm
Skin pale and clammy
Shallow respirations
Nausea
Weak pulse and hypotension
If the pain not relieved by glyceryl trinitrate (GTN) then cause is myocardial infarction rather than angina.
First-line treatment of angina and myocardial infarction
Allow patient to rest in position that feels most comfortable:
• in presence of breathlessness this is likely to be the sitting position, whereas syncopal patients will want to lie flat
• often an intermediate position will be most appropriate.
Angina -
Angina results from reduced coronary artery lumen diameter because of atheromatous plaques
Myocardial infarction is usually the result of thrombosis in a coronary artery.
Angina is relieved by rest and nitrates:
• Glyceryl trinitrate spray 400 mg metered dose (sprayed on oral mucosa or under tongue and mouth then closed)
• Give oxygen
• Allow home if attack is mild and the patient recovers rapidly.
Myocardial infarction
If a myocardial infarction is suspected:
• give oxygen
• aspirin tablet 300 mg chewed.
• Pain control
• Vasodilatation of blood vessels to reduce load on heart.
Further management for severe angina or myocardial infarction
• Transfer to Emergency
• Diamorphine 5 mg (2.5 mg in older people) by slow i.v. injection (1 mg/min)
• Early thrombolytic therapy reduces mortality.
Cardiac arrest
• Most cardiac arrests result from arrhythmias associated with acute myocardial infarction or chronic ischaemic heart disease
• The heart arrests in one of three rhythms
— VF (ventricular fibrillation) or pulseless VT (ventricular tachycardia)
— asystole
— PEA (pulseless electrical activity) or EMD (electromechanical dissociation).
Signs and symptoms
• Unconscious
• No breathing
• Absent carotid pulse.
Treatment
• Circulation failure for 4 minutes, or less if the patient is already hypoxaemic, will lead to irreversible brain damage
• Institute early basic life support as holding procedure until early advanced life support is available.
• Transfer to Emergency
• Advanced life support.
Advanced life support for cardiac arrest
Advanced airway management techniques and specific treatment of the underlying cause of cardiac arrest constitute advanced life support (ALS).
Digital X-Ray
PedodonticsDigital X-Ray Systems in Pediatric Dentistry
Digital x-ray systems have revolutionized dental imaging, providing numerous
advantages over traditional film-based radiography. Understanding the technology
behind these systems, particularly in the context of pediatric patients, is
essential for dental professionals.
1. Digital X-Ray Technology
Solid State Detector Technology:
Digital x-ray systems utilize solid-state detector technology,
primarily through Charge-Coupled Devices (CCD) or Complementary
Metal Oxide Semiconductors (CMOS) for image acquisition.
These detectors convert x-ray photons into electronic signals, which
are then processed to create digital images.
2. Challenges with Wired Sensors in Young Children
Tolerability Issues:
Children under 4 or 5 years of age may have difficulty tolerating
wired sensors due to their limited understanding of the procedure.
The presence of electronic wires can lead to:
Fear or anxiety about the procedure.
Physical damage to the cables, as young children may "chew" on
them or pull at them during the imaging process.
Recommendation:
For these reasons, a phosphor-based digital x-ray system may
be more suitable for pediatric patients, as it minimizes the discomfort
and potential for damage associated with wired sensors.
3. Photostimulable Phosphors (PSPs)
Definition:
Photostimulable phosphors (PSPs), also known as storage phosphors,
are used in digital imaging for image acquisition.
Functionality:
Unlike traditional panoramic or cephalometric screen materials, PSPs
do not fluoresce instantly to produce light photons.
Instead, they store incoming x-ray photon information as a latent
image, similar to conventional film-based radiography.
Image Processing:
After exposure, the plates containing the stored image are scanned
by a laser beam in a drum scanner.
The laser excites the phosphor, releasing the stored energy as an
electronic signal.
This signal is then digitized, with various gray levels assigned to
points on the curve to create the final image.
4. Available Phosphor Imaging Systems
Several manufacturers provide phosphor imaging systems suitable for dental
practices:
Soredex: Digora
Air Techniques: Scan X
Gendex: Denoptix
Sedative-Hypnotic and Anxiolytic Drugs
Pharmacology
Sedative-Hypnotic Drugs
Sedative drug is the drug that reduce anxiety (anxiolytic) and produce sedation and referred to as minor tranquillisers.
Hypnotic drug is the drug that induce sleep
Effects: make you sleepy; general CNS depressants
Uses: sedative-hypnotic (insomnia ), anxiolytic (anxiety, panic, obsessive compulsive, phobias), muscle relaxant (spasticity, dystonias), anticonvulsant (absence, status epilepticus, generalized seizures—rapid tolerance develops), others (pre-operative medication and endoscopic procedures, withdrawal from chronic use of ethanol or other CNS depressants)
1- For panic disorder alprazolam is effective.
2- muscle disorder: (reduction of muscle tone and coordination) diazepam is useful in treatment of skeletal muscle spasm e.g. muscle strain and spasticity of degenerative muscle diseases.
3-epilepsy: by increasing seizure threshold.
Clonazepam is useful in chronic treatment of epilepsy while diazepam is drug of choice in status epilepticus.
4-sleep disorder: Three BDZs are effective hypnotic agents; long acting flurazepam, intermediate acting temazepam and short
acting triazolam. They decrease the time taken to get to sleep They increase the total duration of sleep
5-control of alcohol withdrawals symptoms include diazepam, chlordiazepoxide, clorazepate and oxazepam.
6-in anesthesia: as preanesthetic amnesic agent (also in cardioversion) and as a component of balanced anesthesia
Flurazepam significantly reduce both sleep induction time and numbers of awakenings and increase duration of sleep and little rebound insomnia. It may cause daytime sedation.
Temazepam useful in patients who experience frequent awakening, peak sedative effect occur 2-3 hr. after an oral dose.
Triazolam used to induce sleep in recurring insomnia and in individuals have difficulty in going to sleep, tolerance develop within few days and withdrawals result in rebound insomnia therefore the drug used intermittently.
Drugs and their actions
1. Benzodiazepines: enhance the effect of gamma aminobutyric acid (GABA) at GABA receptors on chloride channels. This increases chloride channel conductance in the brain (GABA A A receptors are ion channel receptors).
2. Barbiturates: enhance the effect of GABA on the chloride channel but also increase chloride channel conductance independently of GABA, especially at high doses
3. Zolpidem and zaleplon: work in a similar manner to benzodiazepines but do so only at the benzodiazepine (BZ1) receptor type. (Both BZ1and BZ2 are located on chloride channels.)
4. Chloral hydrate: probably similar action to barbiturates.
5. Buspirone: partial agonist at a specific serotonin receptor (5-HT1A).
6. Other sedatives (e.g., mephenesin, meprobamate, methocarbamol, carisoprodol, cyclobenzaprine):
mechanisms not well-described. Several mechanisms may be involved.
7. Baclofen: stimulates GABA linked to the G protein, Gi , resulting in an increase in K + conductance and a decrease in Ca2+ conductance. (Other drugs mentioned above do not bind to the GABA B receptor.)
8. Antihistamines (e.g., diphenhydramine): block H1 histamine receptors. Doing so in the CNS leads to sedation.
9. Ethyl alcohol: its several actions include a likely effect on the chloride channel.