NEET MDS Synopsis
Composite Cavity Preparation
Conservative DentistryComposite Cavity PreparationComposite cavity preparations are designed to optimize the placement and
retention of composite resin materials in restorative dentistry. There are three
basic designs for composite cavity preparations: Conventional, Beveled
Conventional, and Modified. Each design has specific characteristics and
indications based on the clinical situation.
1. Conventional Preparation DesignA. Characteristics
Design: Similar to cavity preparations for amalgam
restorations.
Shape: Box-like cavity with slight occlusal
convergence, flat floors, and undercuts in dentin.
Cavosurface Angle: Near 90° (butt joint), which
provides a strong interface for the restoration.
B. Indications
Moderate to Large Class I and Class II Restorations:
Suitable for larger cavities where significant tooth structure is missing.
Replacement of Existing Amalgam: When an existing
amalgam restoration needs to be replaced, a conventional preparation is
often indicated.
Class II Cavities Extending onto the Root: In cases
where the cavity extends onto the root, a conventional design is preferred
to ensure adequate retention and support.
2. Beveled Conventional PreparationA. Characteristics
Enamel Cavosurface Bevel: Incorporation of a bevel at
the enamel margin to increase surface area for bonding.
End-on-Etching: The bevel allows for more effective
etching of the enamel rods, enhancing adhesion.
Benefits:
Improves retention of the composite material.
Reduces microleakage at the restoration interface.
Strengthens the remaining tooth structure.
B. Preparation Technique
Bevel Preparation: The bevel is created using a
flame-shaped diamond instrument, approximately 0.5 mm wide and angled at 45°
to the external enamel surface.
C. Indications
Large Area Restorations: Ideal for restoring larger
areas of tooth structure.
Replacing Existing Restorations: Suitable for class
III, IV, and VI cavities where composite is used to replace older
restorations.
Rarely Used for Posterior Restorations: While
effective, this design is less commonly used for posterior teeth due to
aesthetic considerations.
3. Modified PreparationA. Characteristics
Depth of Preparation: Does not routinely extend into
dentin; the depth is determined by the extent of the carious lesion.
Wall Configuration: No specified wall configuration,
allowing for flexibility in design.
Conservation of Tooth Structure: Aims to conserve as
much tooth structure as possible while obtaining retention through
micro-mechanical means (acid etching).
Appearance: Often has a scooped-out appearance,
reflecting its conservative nature.
B. Indications
Small Cavitated Carious Lesions: Best suited for small
carious lesions that are surrounded by enamel.
Correcting Enamel Defects: Effective for addressing
minor enamel defects without extensive preparation.
C. Modified Preparation Designs
Class III (A and B): For anterior teeth, focusing on
small defects or carious lesions.
Class IV (C and D): For anterior teeth with larger
defects, ensuring minimal loss of healthy tooth structure.
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).
Emergency conditions in Dental Clinics p1
Oral Medicine
Emergency conditions in Dental Clinics
Faint - due to Pain or anxiety.
Signs and symptoms
• May be preceded by nausea and closing in of visual fields
• Pallor and sweating
• Heart rate below 60 beats/min (bradycardia) during attack.
T/t
• Give oxygen
• Expect prompt recovery.
• Need to encourage oxygenated blood flow to brain as rapidly as possible
• May need to block vagal activity with atropine and allow heart rate to increase.
If the patient is slow to recover, consider other diagnosis or give 0.3-1 mg atropine i.v.
Hyperventilation- due to Anxiety
Signs and symptoms
• Light-headed
• Tingling in the extremities
• Muscle spasm may lead to characteristic finger position (carpopedal spasm).
Treatment
• Reassure
• Ask patient to re-breathe from cupped hands or reservoir bag of inhalational sedation or general anaesthetic apparatus.
• Reduce anxiety
• Over-breathing has blown off carbon dioxide, resulting in brain blood vessel vasoconstriction. Return carbon dioxide levels in blood to normal.
Postural hypotension- More likely to occur if the patient is taking betablockers,which reduce the capacity to compensate for normal cardiovascular postural changes.
Signs and symptoms
• Light-headed
• Dizzy
• Loss of consciousness on returning to upright or standing position from supine position.
Treatment
Lay the patient flat and give oxygen
Sit the patient up very slowly.
Encourage oxygenated blood flow to brain.
Diabetic emergencies: hypoglycaemia- Patient may have taken medication as normal but not eaten before dental visit.
Signs and symptoms
• Shaking and trembling
• Sweating
• Hunger
• Headache and confusion.
Treatment
• If the patient is conscious, give three sugar lumps or glucose and a little water or glucose oral gel; repeated if necessary in 10 minutes
• If the patient is unconscious, inject 1 mg (1 unit) glucagon by any route (subcutaneous, intramuscular or i.v.).
Return blood glucose level to normal by giving glucose or by converting the patient's own glycogen to glucose by giving glucagon.
Further management
• Transfer the patient to A&E
• Give up to 50 ml 20% glucose i.v. infusion followed by 0.9% saline flush as the glucose damages the vein
• Expect prompt recovery.
Grand mal epileptic seizure- Usually the patient is a known epileptic
• Epilepsy may not be well controlled
• Seizure may be initiated by anxiety or by flickering light tube.
Signs and symptoms
- Sudden loss of consciousness associated with tonic phase in which there is sustained muscular contraction affecting all muscles, including respiratory and mastication
- Breathing may cease and the patient becomes cyanosed
- The tongue may be bitten and incontinence occur After about 30 seconds, a clonic phase supervenes, with violent jerking movements of limbs and trunk.
Treatment• Ensure patient is not at risk of injury during the convulsions but do not attempt to restrain convulsive movements
• Make no attempt to put anything in mouth or between the teeth
• After movements have subsided, place the patient in the recovery position and check airway
• The patient may be confused after the fit: reassure and offer sympathy
• After full recovery, send the patient home unless the seizure was atypical or prolonged or injury occurred.
• Maintain oxygenated blood to brain
• Protect from physical harm
• Administer anticonvulsant.
Further management
Risk of brain damage is increased with length of attack; therefore, treatment should aim to terminate seizure as soon as possible.
If convulsive seizures continue for 15 minutes or longer or are repeated rapidly (status epilepticus):
• transfer to A&E
• remove dentures, insert Guedel or nasopharyngeal airway
• give oxygen
• give 10-20 mg i.v. diazepam (2.5 mg/30 s) as Diazemuls but beware of respiratory depression, or diazepam solution for rectal administration in hospital.
Sub-Stages of Adolescence
PedodonticsThree Sub-Stages of Adolescence
Adolescence is a critical developmental period characterized by significant
physical, emotional, and social changes. It is typically divided into three
sub-stages: early adolescence, middle adolescence, and late adolescence. Each
sub-stage has distinct characteristics that influence the development of
identity, social relationships, and behavior.
Sub-Stages of Adolescence
1. Early Adolescence (Approximately Ages 10-13)
Characteristics:
Casting Off of Childhood Role: This stage marks the
transition from childhood to adolescence. Children begin to distance
themselves from their childhood roles and start to explore their
emerging identities.
Physical Changes: Early physical development
occurs, including the onset of puberty, which brings about changes in
body shape, size, and secondary sexual characteristics.
Cognitive Development: Adolescents begin to think
more abstractly and critically, moving beyond concrete operational
thinking.
Emotional Changes: Increased mood swings and
emotional volatility are common as adolescents navigate their new
feelings and experiences.
Social Changes: There is a growing interest in peer
relationships, and friendships may begin to take on greater importance
- Exploration of Interests: Early adolescents often
start to explore new interests and hobbies, which can lead to the
formation of new social groups.
2. Middle Adolescence (Approximately Ages 14-17)
Characteristics:
Participation in Teenage Subculture: This stage is
characterized by a deeper involvement in peer groups and the teenage
subculture, where social acceptance and belonging become paramount.
Identity Formation: Adolescents actively explore
different aspects of their identity, including personal values, beliefs,
and future aspirations.
Increased Independence: There is a push for greater
autonomy from parents, leading to more decision-making and
responsibility.
Romantic Relationships: The exploration of romantic
relationships becomes more prominent, influencing social dynamics and
emotional experiences.
Risk-Taking Behavior: Middle adolescents may engage
in risk-taking behaviors as they seek to assert their independence and
test boundaries.
3. Late Adolescence (Approximately Ages 18-21)
Characteristics:
Emergence of Adult Behavior: Late adolescence is
marked by the transition into adulthood, where individuals begin to take
on adult roles and responsibilities.
Refinement of Identity: Adolescents solidify their
sense of self, integrating their experiences and values into a coherent
identity.
Future Planning: There is a focus on future goals,
including education, career choices, and long-term relationships.
Social Relationships: Relationships may become more
mature and stable, with a shift from peer-focused interactions to deeper
connections with family and romantic partners.
Cognitive Maturity: Cognitive abilities continue to
develop, leading to improved problem-solving skills and critical
thinking.
Digital Radiology
Radiology
Digital Radiology
Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray ?lms (with emulsion). The image is either directly or indirectly converted into a digital representation that is displayed on a computer screen.
DIGITAL IMAGE RECEPTORS
- charged coupled device (CCD) used
- Pure silicon divided into pixels.
- Electromagnetic energy from visible light or X-rays interacts with pixels to create an electric charge that can be stored.
- Stored charges are transmitted electronically and create an analog output signal and displayed via digital converter (analog to digital converter).
ADVANTAGES OF DIGITAL TECHNIQUE
Immediate display of images.
Enhancement of image (e.g., contrast, gray scale, brightness).
Radiation dose reduction up to 60%.
Major disadvantage: High initial cost of sensors. Decreased image resolution and contrast as compared to D speed ?lms.
DIRECT IMAGING
- CCD or complementary metal oxide semiconductor (CMOS) detector used that is sensitive to electromagnetic radiation.
- Performance is comparable to ?lm radiography for detection of periodontal lesions and proximal caries in noncavitated teeth.
INDIRECT IMAGING
- Radiographic ?lm is used as the image receiver (detector).
- Image is digitized from signals created by a video device or scanner that views the radiograph.
Sensors
STORAGE PHOSPHOR IMAGING SYSTEMS
Phosphor screens are exposed to ionizing radiation which excites BaFBR:EU+2 crystals in the screen storing the image.
A computer-assisted laser then promotes the release of energy from the crystals in the form of blue light.
The blue light is scanned and the image is reconstructed digitally.
ELECTRONIC SENSOR SYSTEMS
X-rays are converted into light which is then read by an electronic sensor such as a CCD or CMOS.
Other systems convert the electromagnetic radiation directly into electrical impulses.
Digital image is created out of the electrical impulses.
Roxithromycin
Pharmacology
Roxithromycin
It is used to treat respiratory tract, urinary and soft tissue infections. Roxithromycin is derived from erythromycin, containing the same 14-membered lactone ring. However, an N-oxime side chain is attached to the lactone ring.
Roxithromycin has similar antimicrobial spectrum as erythromycin, but is more effective against certain gram-negative bacteria, particularly Legionella pneumophilae.
When taken before a meal, roxithromycin is very rapidly absorbed, and diffused into most tissues and Phagocytes Only a small portion of roxithromycin is metabolised. Most of roxithromycin is secreted unchanged into the bile and some in expired air
THE ADRENAL GLANDS
General Pathology
THE ADRENAL GLANDS
ADRENAL CORTEX
The adrenal cortex synthesizes three different types of steroids:
1. Glucocorticoids (principally cortisol), which are synthesized primarily in the zona fasciculata
2. Mineralocorticoids, the most important being aldosterone, which is generated in the zona glomerulosa; and
3. Sex steroids (estrogens and androgens), which are produced largely in the zona reticularis.
ADRENAL MEDULLA
The adrenal medulla is populated by cells derived from the neural crest (chromaffin cells) and their supporting (sustentacular) cells.
They secrete catecholamines in response to signals from preganglionic nerve fibers inthe sympathetic nervous system.
Osteonecrosis
General Pathology
Osteonecrosis (Avascular Necrosis)
Ischemic necrosis with resultant bone infarction occurs mostly due to fracture or after corticosteroid use. Microscopically, dead bon trabevulae (characterized by empty lacunae) are interspersed with areas of fat necrosis.
The cortex is usually not affected because of collateral blood supply; in subchondral infarcts, the overlying articular cartilage also remains viable because the synovial fluid can provide nutritional support. With time, osteoclasts can resorb many of the necrotic bony trabeculae; any dead bone fragments that remain act as scaffolds for new bone formation, a process called creeping substitution.
Symptoms depend on the size and location of injury. Subchondral infarcts often collapse and can lead to severe osteoarthritis.