NEET MDS Synopsis
Types and Source of Haemorrhage
Surgery
Types of Haemorrhage
Hemorrhaging is broken down into four classes
Class I Hemorrhage involves up to 15% of blood volume.
There is typically no change in vital signs and fluid resuscitation is not usually necessary.
Class II Hemorrhage involves 15-30% of total blood volume.
A patient is often tachycardic (rapid heart beat) with a reduction in the difference between the systolic and diastolic blood pressures.
The body attempts to compensate with peripheral vasoconstriction. Skin may start to look pale and be cool to the touch.
The patient may exhibit slight changes in behavior.
Volume resuscitation with crystalloids (Saline solution or Lactated Ringer's solution) is all that is typically required. Blood transfusion is not usually required.
Class III Hemorrhage involves loss of 30-40% of circulating blood volume.
The patient's blood pressure drops, the heart rate increases, peripheral hypoperfusion (shock) with diminished capillary refill occurs, and the mental status worsens.
Fluid resuscitation with crystalloid and blood transfusion are usually necessary.
Class IV Hemorrhage involves loss of >40% of circulating blood volume.
The limit of the body's compensation is reached and aggressive resuscitation is required to prevent death.
Source of Haemorrhage
- Extra dural haemorrhage - middle meningeal artery
- Sub dural haemorrhage - bridging or diploic veins
- Sub arachnoid haemorrhage - rupture on berry aneursym
- Tennis bal injury to eye - circulis iridis major
- Epistaxis - Sphenopalantine artery
- During tonsillectomy - para tonsilaar veins, tonsilar and ascending palantine artery
- Tracheostomy - isthemus and inferior thyroid vein
- Heamoptysis-bronchial artery
- Gastric ulcer- left gastric, splenic artery
- Duodenal ulcer - gastroduodenal artery
- Hemmorrhoids - submucous rectal venous plexus formed by superior rectal vein & inferior rectal vein
- Retropubic proastatectomy - dorsal venous plexus
- Hysterectomy - internal illac artery
- Menstruation - spiral arteries
Bone Graft Materials
PeriodontologyBone Graft Materials
Bone grafting is a critical procedure in periodontal and dental surgery,
aimed at restoring lost bone and supporting the regeneration of periodontal
tissues. Various materials can be used for bone grafting, each with unique
properties and applications.
A. Osseous Coagulum
Composition: Osseous coagulum is a mixture of bone dust
and blood. It is created using small particles ground from cortical bone.
Sources: Bone dust can be obtained from various
anatomical sites, including:
Lingual ridge of the mandible
Exostoses
Edentulous ridges
Bone distal to terminal teeth
Application: This material is used in periodontal
surgery to promote healing and regeneration of bone in areas affected by
periodontal disease.
B. Bioactive Glass
Composition: Bioactive glass consists of sodium and
calcium salts, phosphates, and silicon dioxide.
Function: It promotes bone regeneration by forming a
bond with surrounding bone and stimulating cellular activity.
C. HTR Polymer
Composition: HTR Polymer is a non-resorbable,
microporous, biocompatible composite made from polymethyl methacrylate
(PMMA) and polyhydroxymethacrylate.
Application: This material is used in various dental
and periodontal applications due to its biocompatibility and structural
properties.
D. Other Bone Graft Materials
Sclera: Used as a graft material due to its collagen
content and biocompatibility.
Cartilage: Can be used in certain grafting procedures,
particularly in reconstructive surgery.
Plaster of Paris: Occasionally used in bone grafting,
though less common due to its non-biological nature.
Calcium Phosphate Biomaterials: These materials are
osteoconductive and promote bone healing.
Coral-Derived Materials: Natural coral can be processed
to create a scaffold for bone regeneration.
CASTING DEFECTS
Dental Materials
CASTING DEFECTS
Classification :
1) Distortion.
2) Surface roughness .
3) Porosity .
4)Incomplete casting .
5) Oxidation .
6) Sulfur contamination .
Distortion
It is usually due to the distortion of wax pattern.
To avoid this :
Manipulation of the wax at its softening temp
Invest the pattern at the earliest .
If storage is necessary store it in a refrigerator .
Surface roughness
May be due to :
Air bubbles on the wax pattern .
Cracks due to rapid heating of the investment .
High W/P ratio .
Prolonged heating of the mold cavity .
Overheating of the gold alloy .
Too high or too low casting pressure .
Composition of the investment .
Foreign body inclusion.
POROSITY
May be internal or external .
External porosity causes discolouration .
Internal porosity weakens the restoration .
Classification of porosity .
I .Those caused by solidification shrinkage :
a) Localised shrinkage porosity .
b) Suck back porosity .
c) Microporosity .
They are usually irregular in shape .
II ) Those caused by gas :
a) Pin hole porosity .
b) Gas inclusions .
c) Subsurface porosity .
Usually they are spherical in shape .
III ) Those caused by air trapped in the mold :
Back pressure porosity .
Localised shrinkage porosity
Large irregular voids found near sprue casting junction.
Occurs when cooling sequence is incorrect .
If the sprue solidifies before the rest of the casting , no more molten metal is supplied from the sprue which can cause voids or pits (shrink pot porosity )
This can be avoided by -
- using asprue of correct thickness .
- Attach the sprue to the thickest portion of the pattern .
-Flaring of the sprue at the point of atttachment .
-Placing a reservoir close to the pattern .
Suck back porosity
It is an external void seen in the inside of a crown opposite the sprue .
Hot spot is created which freezes last .
It is avoided by :
Reducing the temp difference between the mold & molten alloy .
Microporosity :
Fine irregular voids within the casting .
Occurs when casting freezes rapidly .
Also when mold or casting temp is too low .
Pin hole porosity :
Upon solidification the dissolved gases are expelled from the metal causing tiny voids .
Pt & Pd absorb Hydrogen .
Cu & Ag absorb oxygen .
Gas inclusion porosities
Larger than pin hole porosities .
May be due to dissolved gases or due to gases Carried in or trapped by molten metal .
Apoorly adjusted blow torech can also occlude gases .
Back pressure porosity
This is caused by inadequate venting of the mold .The sprue pattern length should be adjusted so that there is not more than ¼” thickness of the investmentbetween the bottom of the casting .
This can be prevented by :
- using adequate casting force .
-use investment of adequate porosity .
-place the pattern not more than 6-8 mm away from tne end of the casting .
Casting with gas blow holes
This is due to any wax residue in the mold .
To eliminate this the burnout should be done with the sprue hol facing downwards for the wax pattern to run down.
Incomplete casting
This is due to :
- insufficient alloy .
-Alloy not able to enter thin parts of the mold .
-When the mold is not heated to the casting temp .
-Premature solidification of the alloy .
-sprues blocked with foreign bodies .
-Back pressure of gases .
-low casting pressure .
-Alloy not sufficiently molten .
Too bright & shiny casting with short & rounded margins :
occurs when wax is eliminated completely ,it combines with oxygen or air to form carbon monoxide .
Small casting :
occurs when proper expansion is not obtained & due to the shrinkage of the impression .
Contamination of the casting
1) Due to overheating there is oxidation of metal .
2) Use of oxidising zone of the flame .
3) Failure to use a flux .
4) Due to formation sulfur compounds .
Black casting
It is due to :
1) Overheating of the investment .
2) Incomplete elimination of the wax .
Amoxicillin
Pharmacology
Amoxicillin
a moderate-spectrum
β-lactam antibiotic used to treat bacterial infections caused by susceptible
Mode of action Amoxicillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria. microorganisms. It is usually the drug of choice within the class because it is better absorbed, following oral administration, than other beta-lactam antibiotics. Amoxicillin is susceptible to degradation by β-lactamase-producing bacteria, and so is often given clavulanic acid.
Microbiology Amoxicillin is a moderate-spectrum antibiotic active against a wide range of Gram-positive, and a limited range of Gram-negative organisms
Susceptible Gram-positive organisms : Streptococcus spp., Diplococcus pneumoniae, non β-lactamase-producing Staphylococcus spp., and Streptococcus faecalis.
Susceptible Gram-negative organisms Haemophilus influenzae, Neisseria gonorrhoeae, Neisseria meningitidis, Escherichia coli, Proteus mirabilis and Salmonella spp.
Resistant organisms Penicillinase producing organisms, particularly penicillinase producing Staphylococcus spp. Penicillinase-producing N. gonorrhoeae and H. influenzae are also resistant
All strains of Pseudomonas spp., Klebsiella spp., Enterobacter spp., indole-positive
Proteus spp., Serratia marcescens, and Citrobacter spp. are resistant.
The incidence of β-lactamase-producing resistant organisms, including E. coli, appears to be increasing.
Amoxicillin and Clavulanic acid Amoxicillin is sometimes combined with clavulanic acid, a β-lactamase inhibitor, to increase the spectrum of action against
Gram-negative organisms, and to overcome bacterial antibiotic resistance mediated through β-lactamase production.
Types of Crying
PedodonticsTypes of Crying
Obstinate Cry:
Characteristics: This cry is loud, high-pitched,
and resembles a siren. It often accompanies temper tantrums, which may
include kicking and biting.
Emotional Response: It reflects the child's
external response to anxiety and frustration.
Physical Manifestation: Typically involves a lot of
tears and convulsive sobbing, indicating a high level of distress.
Frightened Cry:
Characteristics: This cry is not about getting what
the child wants; instead, it arises from fear that overwhelms the
child's ability to reason.
Physical Manifestation: Usually involves small
whimpers, indicating a more subdued response compared to the obstinate
cry.
Hurt Cry:
Characteristics: This cry is a reaction to physical
discomfort or pain.
Physical Manifestation: It may start with a single
tear that runs down the child's cheek without any accompanying sound or
resistance, indicating a more internalized response to pain.
Compensatory Cry
Characteristics:
This type of cry is not a traditional cry; rather, it is a sound
that the child makes in response to a specific stimulus, such as the
sound of a dental drill.
It is characterized by a constant whining noise rather than the
typical crying sounds associated with distress.
Physical Manifestation:
There are no tears or sobs associated with this cry. The child
does not exhibit the typical signs of emotional distress that
accompany other types of crying.
The sound is directly linked to the presence of the stimulus
(e.g., the drill). When the stimulus stops, the whining also ceases.
Emotional Response:
The compensatory cry may indicate a child's attempt to cope with
discomfort or fear in a situation where they feel powerless or
anxious. It serves as a way for the child to express their
discomfort without engaging in more overt forms of crying.
COMPOSITE RESINS -Reaction
Dental Materials
COMPOSITE RESINS
Reaction
Free radical polymerization
Monomers + initiator. + accelerators-+ polymer molecules
Initiators-start polymerization by decomposing and reacting with monomer
Accelerators-speed up initiator decomposition
Amines used for accelerating self –curing systems
Light used for accelerating light-curing systems
Retarders or inhibitors-prevent premature polymerization
Infections caused by N. meningiditis
General Pathology
Infections caused by N. meningiditis
1. Bacteremia without sepsis. Organism spreads to blood but no major reaction.
2. Meningococcemia without meningitis. Fever, headache, petechia, hypotension, disseminated intravascular coagulation. The Waterhouse-Friderichsen Syndrome is a rapid, progressive meningococcemia with shock, organ failure, adrenal necrosis, and death.
3. Meningitis with meningococcemia. Sudden onset fever, chills, headache, confusion, nuchal rigidity. This occurs rapidly.
4. Meningoencephalitis. Patients are deeply comatose.
Diagnosis made by examining CSF.
Host Defense Mechanisms
PeriodontologyBacterial Properties Involved in Evasion of Host Defense Mechanisms
Bacteria have evolved various strategies to evade the host's immune defenses,
allowing them to persist and cause disease. Understanding these mechanisms is
crucial for developing effective treatments and preventive measures against
bacterial infections, particularly in the context of periodontal disease. This
lecture will explore the bacterial species involved, their properties, and the
biological effects of these properties on host defense mechanisms.
Host Defense Mechanisms and Bacterial Evasion Strategies
Specific Antibody Evasion
Bacterial Species:
Porphyromonas gingivalis
Prevotella intermedia
Prevotella melaninogenica
Capnocytophaga spp.
Bacterial Property:
IgA- and IgG-degrading proteases
Biologic Effect:
Degradation of specific antibodies, which impairs the host's
ability to mount an effective immune response against these
bacteria.
Evasion of Polymorphonuclear Leukocytes (PMNs)
Bacterial Species:
Aggregatibacter actinomycetemcomitans
Fusobacterium nucleatum
Porphyromonas gingivalis
Treponema denticola
Bacterial Properties:
Leukotoxin: A toxin that can induce apoptosis
in PMNs.
Heat-sensitive surface protein: May interfere
with immune recognition.
Capsule: A protective layer that inhibits
phagocytosis.
Inhibition of superoxide production: Reduces
the oxidative burst necessary for bacterial killing.
Biologic Effects:
Inhibition of PMN function, leading to decreased bacterial
killing.
Induction of apoptosis (programmed cell death) in PMNs, reducing
the number of immune cells available to fight infection.
Inhibition of phagocytosis, allowing bacteria to evade
clearance.
Evasion of Lymphocytes
Bacterial Species:
Aggregatibacter actinomycetemcomitans
Fusobacterium nucleatum
Tannerella forsythia
Prevotella intermedia
Bacterial Properties:
Leukotoxin: Induces apoptosis in lymphocytes.
Cytolethal distending toxin: Affects cell cycle
progression and induces cell death.
Heat-sensitive surface protein: May interfere
with immune recognition.
Cytotoxin: Directly damages immune cells.
Biologic Effects:
Killing of mature B and T cells, leading to a weakened adaptive
immune response.
Nonlethal suppression of lymphocyte activity, impairing the
immune response.
Impairment of lymphocyte function by arresting the cell cycle,
leading to decreased responses to antigens and mitogens.
Induction of apoptosis in mononuclear cells and lymphocytes,
further reducing immune capacity.
Inhibition of Interleukin-8 (IL-8) Production
Bacterial Species:
Porphyromonas gingivalis
Bacterial Property:
Inhibition of IL-8 production by epithelial cells.
Biologic Effect:
Impairment of PMN response to bacteria, leading to reduced
recruitment and activation of neutrophils at the site of infection.