NEET MDS Synopsis
Drugs used to induce vomiting
Pharmacology
Drugs used to induce vomiting
In case of poisoning with noncorrosive agents, and assuming incomplete absorption of the poison has taken place, induction of vomiting can be carried out. One of the drugs used for this purpose is emetine which causes irritation of the upper gut and, on absorption, it also acts on CTZ.
Chemotherapeutic agents (or their metabolites) can directly activate the medullary chemoreceptor trigger zone or vomiting center; several neuroreceptors, including dopamine receptor Type 2 and serotonin Type 3 (5-HT3) from cell damage(GIT and pharynx) play roles in vomiting.
Springs in Orthodontics
OrthodonticsSprings in Orthodontics
Springs are essential components of removable orthodontic appliances,
playing a crucial role in facilitating tooth movement. Understanding the
mechanics of springs, their classifications, and their applications is vital for
effective orthodontic treatment.
Springs are active components of removable orthodontic appliances
that deliver forces to teeth and/or skeletal structures, inducing changes in
their positions.
Mechanics of Tooth Movement: To achieve effective tooth
movement, it is essential to apply light and continuous forces. Heavy forces
can lead to damage to the periodontium, root resorption, and other
complications.
Components of a Removable Appliance
A removable orthodontic appliance typically consists of three main
components:
Baseplate: The foundation that holds the appliance
together and provides stability.
Active Components: These include springs, clasps, and
other elements that exert forces on the teeth.
Retention Components: These ensure that the appliance
remains in place during treatment.
Springs as Active Components
Springs are integral to the active components of removable appliances. They
are designed to exert specific forces on the teeth to achieve desired movements.
Components of a Spring
Wire Material: Springs are typically made from
stainless steel or other resilient materials that can withstand repeated
deformation.
Shape and Design: The design of the spring influences
its force delivery and stability.
Classification of Springs
Springs can be classified based on various criteria:
1. Based on the Presence or Absence of Helix
Simple Springs: These springs do not have a helix and
are typically used for straightforward tooth movements.
Compound Springs: These springs incorporate a helix,
allowing for more complex movements and force applications.
2. Based on the Presence of Loop or Helix
Helical Springs: These springs feature a helical
design, which provides a continuous force over a range of motion.
Looped Springs: These springs have a looped design,
which can be used for specific tooth movements and adjustments.
3. Based on the Nature of Stability
Self-Supported Springs: Made from thicker gauge wire,
these springs can support themselves and maintain their shape during use.
Supported Springs: Constructed from thinner gauge wire,
these springs lack adequate stability and are often encased in a metallic
tube to provide additional support.
Applications of Springs in Orthodontics
Space Maintenance: Springs can be used to maintain
space in the dental arch during the eruption of permanent teeth.
Tooth Movement: Springs are employed to move teeth into
desired positions, such as correcting crowding or aligning teeth.
Retention: Springs can also be used in retainers to
maintain the position of teeth after orthodontic treatment.
Seddon’s Classification of Nerve Injuries
Oral and Maxillofacial SurgerySeddon’s Classification of Nerve Injuries
Neuropraxia:
Definition: This is the mildest form of nerve
injury, often caused by compression or mild trauma.
Sunderland Classification: Type I (10).
Nerve Sheath: Intact; the surrounding connective
tissue remains undamaged.
Axons: Intact; the nerve fibers are not severed.
Wallerian Degeneration: None; there is no
degeneration of the distal nerve segment.
Conduction Failure: Transitory; there may be
temporary loss of function, but it is reversible.
Spontaneous Recovery: Complete recovery is
expected.
Time of Recovery: Typically within 4 weeks.
Axonotmesis:
Definition: This injury involves damage to the
axons while the nerve sheath remains intact. It is often caused by more
severe trauma, such as crush injuries.
Sunderland Classification: Type II (20), Type III
(30), Type IV (40).
Nerve Sheath: Intact; the connective tissue
framework is preserved.
Axons: Interrupted; the nerve fibers are damaged
but the sheath allows for potential regeneration.
Wallerian Degeneration: Yes, partial; degeneration
occurs in the distal segment of the nerve.
Conduction Failure: Prolonged; there is a
longer-lasting loss of function.
Spontaneous Recovery: Partial recovery is possible,
depending on the extent of the injury.
Time of Recovery: Recovery may take months.
Neurotmesis:
Definition: This is the most severe type of nerve
injury, where both the axons and the nerve sheath are disrupted. It
often results from lacerations or severe trauma.
Sunderland Classification: Type V (50).
Nerve Sheath: Interrupted; the connective tissue is
damaged, complicating regeneration.
Axons: Interrupted; the nerve fibers are completely
severed.
Wallerian Degeneration: Yes, complete; degeneration
occurs in both the proximal and distal segments of the nerve.
Conduction Failure: Permanent; there is a lasting
loss of function.
Spontaneous Recovery: Poor to none; recovery is
unlikely without surgical intervention.
Time of Recovery: Recovery may begin by 3 months,
if at all.
Pemphigoid
General Pathology
Pemphigoid
1. Ulcerative lesions on the skin and oral mucosa.
2. An autoimmune disease in which patients have autoantibodies against basal cells (desmosome attachment to the basement membrane).
3. Histologically, the entire epithelium appears to separate from the connective tissue. There is no acantholysis.
4. A positive Nikolsky sign is observed.
5. Complications include blindness, due to ocular lesions present in some patients.
6. Treatment: corticosteroids.
Piaget's Cognitive Theory
PedodonticsPiaget's Cognitive Theory
Active Learning:
Piaget believed that children are not merely influenced by their
environment; instead, they actively engage with it. They construct their
understanding of the world through experiences and interactions.
Adaptation:
Adaptation is the process through which individuals adjust their
cognitive structures to better understand their environment. This
process consists of three functional variants: assimilation,
accommodation, and equilibration.
The Three Functional Variants of Adaptation
i. Assimilation:
Definition: Assimilation involves incorporating new
information or experiences into existing cognitive schemas (mental
frameworks). It is the process of recognizing and relating new objects or
experiences to what one already knows.
Example: A child who knows what a dog is may see a new
breed of dog and recognize it as a dog because it fits their existing schema
of "dog."
ii. Accommodation:
Definition: Accommodation occurs when new information
cannot be assimilated into existing schemas, leading to a modification of
those schemas or the creation of new ones. It accounts for changing concepts
and strategies in response to new experiences.
Example: If the same child encounters a cat for the
first time, they may initially try to assimilate it into their "dog" schema.
However, upon realizing that it is not a dog, they must accommodate by
creating a new schema for "cat."
iii. Equilibration:
Definition: Equilibration is the process of balancing
assimilation and accommodation to create stable understanding. It refers to
the ongoing adjustments that individuals make to their cognitive structures
to achieve a coherent understanding of the world.
Example: When a child encounters a variety of animals,
they may go through a cycle of assimilation and accommodation until they
develop a comprehensive understanding of different types of animals,
achieving a state of cognitive equilibrium.
Necrotizing Ulcerative Gingivitis (NUG)
PeriodontologyNecrotizing Ulcerative Gingivitis (NUG)
Necrotizing Ulcerative Gingivitis (NUG), also known as Vincent's disease or
trench mouth, is a severe form of periodontal disease characterized by the
sudden onset of symptoms and specific clinical features.
Etiology and Predisposing Factors
Sudden Onset: NUG is characterized by a rapid onset of
symptoms, often following debilitating diseases or acute respiratory
infections.
Lifestyle Factors: Changes in living habits, such as
prolonged work without adequate rest, poor nutrition, tobacco use, and
psychological stress, are frequently noted in patient histories .
Smoking: Smoking has been identified as a significant
predisposing factor for NUG/NDP .
Immune Compromise: Conditions that compromise the
immune system, such as poor oral hygiene, smoking, and emotional stress, are
major contributors to the development of NUG .
Clinical Presentation
Symptoms: NUG presents with:
Punched-out, crater-like depressions at the crest of interdental
papillae.
Marginal gingival involvement, with rare extension to attached
gingiva and oral mucosa.
Grey, pseudomembranous slough covering the lesions.
Spontaneous bleeding upon slight stimulation of the gingiva.
Fetid odor and increased salivation.
Microbiology
Mixed Bacterial Infection: NUG is caused by a complex
of anaerobic bacteria, often referred to as the fusospirochetal complex,
which includes:
Treponema vincentii
Treponema denticola
Treponema macrodentium
Fusobacterium nucleatum
Prevotella intermedia
Porphyromonas gingivalis
Treatment
Control of Acute Phase:
Clean the wound with an antibacterial agent.
Irrigate the lesion with warm water and 5% vol/vol hydrogen
peroxide.
Prescribe oxygen-releasing mouthwash (e.g., hydrogen peroxide DPF,
sodium perborate DPF) to be used thrice daily.
Administer oral metronidazole for 3 to 5 days. If sensitive to
metronidazole, prescribe penicillin; if sensitive to both, consider
erythromycin or clindamycin.
Use 2% chlorhexidine in select cases for a short duration.
Management of Residual Condition:
Remove predisposing local factors (e.g., overhangs).
Perform supra- and subgingival scaling.
Consider gingivoplasty to correct any residual gingival deformities.
RESPIRATORY DISORDERS - Cystic Fibrosis
PhysiologyCystic Fibrosis
→ Thick mucus coagulates in ducts, produces obstruction, Too thick for cilia to move
→ Major Systems Affected: Respiratory System, G. I. Tract,Reproductive Tract
→ Inherited, autosomal recessive gene, most common fatal genetic disorder
→ Major characteristic, Altered electrolyte composition (Saliva & sweat Na+, K+, Cl-)
→ Family history of Cystic Fibrosis
→ Respiratory Infections & G.I.Tract malabsorption
→ Predisposes lung to Secondary infection (Staphylococcus, Pseudomonas)
→ Damages Respiratory Bronchioles and Alveolar ducts, Produces Fibrosis of Lungs, Large cystic dilations)
Alcohols as Antiseptics
Oral and Maxillofacial SurgeryAlcohols as Antiseptics
Ethanol and isopropyl alcohol are commonly
used as antiseptics in various healthcare settings. They possess antibacterial
properties and are effective against a range of microorganisms, although they
have limitations in their effectiveness against certain pathogens.
Mechanism of Action
Antibacterial Activity: Alcohols exhibit antibacterial
activity against both gram-positive and gram-negative bacteria,
including Mycobacterium tuberculosis.
Protein Denaturation: The primary mechanism by which
alcohols exert their antimicrobial effects is through the denaturation
of proteins. This disrupts cellular structures and functions,
leading to cell death.
Effectiveness and Recommendations
Contact Time:
According to Spaulding (1939), for alcohol to achieve maximum
effectiveness, it must remain in contact with the microorganisms for at
least 10 minutes. This extended contact time is crucial
for ensuring adequate antimicrobial action.
Concentration:
Solutions of 70% alcohol are more effective than
higher concentrations (e.g., 90% or 100%). The presence of water in the
70% solution enhances the denaturation process of proteins, as reported
by Lawrence and Block (1968). Water acts as a co-solvent, allowing for
better penetration and interaction with microbial cells.