NEET MDS Synopsis
Test for Antigen - Antibody Reactions
General MicrobiologyTest for Antigen - Antibody Reactions
Antigens are those substance that stimulates the production of antibodies which, when enter into the body it reacts specifically in a manner that are clearly visible.
Some antigens may not induce antibody production, but instead creates immunological tolerance.
An antigen introduced into the body produces only specific antibodies and will react with only those specific antigens.
These antibodies appear in the serum and tissue fluids. All antibodies are considered as immunoglobulin. They are mainly of five classes; IgG, IgA, IgM, IgD and IgE.
Antigen- antibody reactions are known as serological reactions and are used as serological diagnostic tests for the identification of infectious diseases.
The reaction occurs mainly in three stages;
1. The initial interaction between the antigen and antibody, which produces no visible effects. It is a reversible and rapid reaction.
2. The secondary stage leads to the demonstration proceedings, such as precipitation, agglutination, etc.
3. The tertiary reaction follows the neutralization or destruction of injurious antigens. These results in clinical allergy and other immunological diseases.
There are certain characteristics for antigen-antibody reactions;
1. Reaction is specific.
2. The whole molecules participate in the reaction, and not just a part of it.
3. No denaturation of antigen or antibody occurs during the reaction.
4. The combination usually occurs at the surface.
5. The combination is firm, but reversible
6. Agglutinins formed after agglutination usually are formed by both antigen and antibody together.
7. They can combine in varying proportions.
Measurement of antigen and antibody are made in terms of mass or as units or titre.
Serological reactions include;
1. Precipitation reaction
a soluble antigen combining with the specific antibody in the presence of electrolytes at a suitable temperature and pH forming insoluble precipitins. Commonly used tests are ring test, slide test, tube test, immunodiffusion, etc.
Radial Immunodiffusion
In radial immunodiffusion antibody is incorporated into the agar gel as it is poured and different dilutions of the antigen are placed in holes punched into the agar. As the antigen diffuses into the gel, it reacts with the antibody and when the equivalence point is reached a ring of precipitation is formed .
This test is commonly used in the clinical laboratory for the determination of immunoglobulin levels in patient samples.
Immunoelectrophoresis
In immunoelectrophoresis, a complex mixture of antigens is placed in a well punched out of an agar gel and the antigens are electrophoresed so that the antigen are separated according to their charge. After electrophoresis, a trough is cut in the gel and antibodies are added. As the antibodies diffuse into the agar, precipitin lines are produced in the equivalence zone when an antigen/antibody reaction occurs .
This tests is used for the qualitative analysis of complex mixtures of antigens
This test can also be used to evaluate purity of isolated serum proteins.
Countercurrent electrophoresis
In this test the antigen and antibody are placed in wells punched out of an agar gel and the antigen and antibody are electrophoresed into each other where they form a precipitation line.
2. Agglutination reaction
when a particulate antigen is mixed with its antibody in the presence of electrolytes at a suitable temperature and pH, the particles are clumped or agglutinated. When the antigen is an erythrocyte the term hemagglutination is used.
Applications of agglutination tests
i. Determination of blood types or antibodies to blood group antigens.
ii. To assess bacterial infections
e.g. A rise in titer of an antibody to a particular bacterium indicates an infection with that bacterial type. N.B. a fourfold rise in titer is generally taken as a significant rise in antibody titer.
Passive hemagglutination
The agglutination test only works with particulate antigens. However, it is possible to coat erythrocytes with a soluble antigen (e.g. viral antigen, a polysaccharide or a hapten) and use the coated red blood cells in an agglutination test for antibody to the soluble antigen . This is called passive hemagglutination.
The test is performed just like the agglutination test.
Applications include detection of antibodies to soluble antigens and detection of antibodies to viral antigens.
Coomb's Test (Antiglobulin Test)
DIRECT ANTIGLOBULIN TEST (DAT)
The DAT is used to detect IgG or C3 bound to the surface of the red cell. In patients with hemolysis, the DAT is useful in determining whether there is an immune etiology.
A positive DAT can occur without hemolysis
Immune causes of hemolysis including autoimmune hemolytic anemias, drug induced hemolysis, and delayed or acute hemolytic transfusion reactions are characterized by a positive DAT.
INDIRECT ANTIGLOBULIN TEST (IAT)
The IAT (antibody screen) is performed by incubating patient serum with reagent screening red cells for approximately 20 minutes and then observing for agglutination. If the antibody screen is positive, additional testing is required to determine the specificity of the antibody.
The IAT is used to detect red cell antibodies in patient serum. Approximately 5% of patients have a positive IAT due to IgG antibodies, IgM antibodies, or both.
3. Complement fixation test (CFT)
the ability of antigen antibody complexes to fix complement is made use in this test. Complement is something which takes part in any immunological reaction and absorbed during the combining of antigen with its specific antibody.
The best example of CFT is the Wassermann reaction done for the detection of Syphilis.
4. Neutralization test
different types of these are available. Virus neutralization, toxin neutralization, etc. are some of its kind.
5. Opsonization
this makes use of the determination of opsonic index, which is the ratio of the phagocytic activity of patient’s blood to the phagocytic activity of the normal patient’s for a given bacterium.
6. Immunfluorescence
the method of labeling the antibodies with fluorescent dyes and using them for the detection of antigens in tissues.
7. Radioimmunoassay (RIA)
is a competitive binding radioisotopes and enzymes are used as labels to conjugate with antigens or antibodies.
8. Enzyme Immuno Assay (EIA)
the assays based on the measurement of enzyme labeled antigen or antibody. The most common example is ELISA used to detect HIV.
9. Immunoelectroblot
it uses the sensitivity of Enzyme immunoassay with a greater specificity. Example is Western blot done for the serodiagnosis of HIV infection.
Osteomyelitis
Oral and Maxillofacial SurgeryOsteomyelitis is an infection of the bone that can occur in the jaw,
particularly in the mandible, and is characterized by a range of clinical
features. Understanding these features is essential for effective diagnosis and
management, especially in the context of preparing for the Integrated National
Board Dental Examination (INBDE). Here’s a detailed overview of the clinical
features, occurrence, and implications of osteomyelitis, particularly in adults
and children.
Occurrence
Location: In adults, osteomyelitis is more common in
the mandible than in the maxilla. The areas most frequently affected
include:
Alveolar process
Angle of the mandible
Posterior part of the ramus
Coronoid process
Rarity: Osteomyelitis of the condyle is reportedly rare
(Linsey, 1953).
Clinical Features
Early Symptoms
Generalized Constitutional Symptoms:
Fever: High intermittent fever is common.
Malaise: Patients often feel generally unwell.
Gastrointestinal Symptoms: Nausea, vomiting, and
anorexia may occur.
Pain:
Nature: Patients experience deep-seated, boring,
continuous, and intense pain in the affected area.
Location: The pain is typically localized to the
mandible.
Neurological Symptoms:
Paresthesia or Anesthesia: Intermittent paresthesia
or anesthesia of the lower lip can occur, which helps differentiate
osteomyelitis from an alveolar abscess.
Facial Swelling:
Cellulitis: Patients may present with facial
cellulitis or indurated swelling, which is more confined to the
periosteal envelope and its contents.
Mechanisms:
Thrombosis of the inferior alveolar vasa nervorum.
Increased pressure from edema in the inferior alveolar canal.
Dental Symptoms: Affected teeth may be tender to
percussion and may appear loose.
Trismus:
Limited mouth opening due to muscle spasm or inflammation in the
area.
Pediatric Considerations
In children, osteomyelitis can present more severely and may be
characterized by:
Fulminating Course: Rapid onset and progression of
symptoms.
Severe Involvement: Both maxilla and mandible can
be affected.
Complications: The presence of unerupted developing
teeth buds can complicate the condition, as they may become necrotic and
act as foreign bodies, prolonging the disease process.
TMJ Involvement: Long-term involvement of the
temporomandibular joint (TMJ) can lead to ankylosis, affecting the
growth and development of facial structures.
Radiographic Changes
Timing of Changes: Radiographic changes typically occur
only after the initiation of the osteomyelitis process.
Bone Loss: Significant radiographic changes are noted
only after 30% to 60% of mineralized bone has been destroyed.
Delay in Detection: This degree of bone alteration
requires a minimum of 4 to 8 days after the onset of acute osteomyelitis for
changes to be visible on radiographs.
MAXILLARY CUSPIDS
Dental Anatomy
MAXILLARY CUSPIDS (CANINE)
The maxillary cuspid is usually the longest tooth in either jaw. canines are considered the corner stones of the dental arch They are the only teeth in the dentition with a single cusp.
Facial Surface:- The facial surface of the crown differs considerably from that of the maxillary central or lateral incisors. In that the incisal edges of the central and lateral incisor are nearly straight, the cuspid has a definite point, or cusp. There are two cutting edges, the mesioincisal and the distoincisal. The distoincisal cutting edge is the longer of the two. The developmental grooves prominent on the facial surface extending two-thirds of the distance from the tip of the cusp to the cervical line. The distal cusp ridge is longer than the mesial cusp ridge
Lingual Surface: Distinct mesial and distal marginal ridges, a well-devloped cingulum, and the cusp ridges form the boundries of the lingual surface. The prominent lingual ridge extends from the cusp tip to the cingulum, dividing the lingual surface into mesial and distal fossae.
Proximal: The mesial and distal aspects present a triangular outline. They resemble the incisors, but are more robust--especially in the cingulum region
Incisal: The asymmetry of this tooth is readily apparent from this aspect. It usually thicker labiolingually than it is mesiodistally. The tip of the cusp is displaced labially and mesial to the central long axis of this tooth.
Root Surface:-The root is single and is the longest root in the arch. It is usually twice the length of the crown.
MAXILLARY FIRST BICUSPID
Dental Anatomy
MAXILLARY FIRST BICUSPID (PREMOLARS)
It is considered to be the typical bicuspid. (The word "bicuspid" means "having two cusps.")
Facial: The buccal surface is quite rounded and this tooth resembles the maxillary canine. The buccal cusp is long; from that cusp tip, the prominent buccal ridge descends to the cervical line of the tooth.
Lingual: The lingual cusp is smaller and the tip of that cusp is shifted toward the mesial. The lingual surface is rounded in all aspects.
Proximal: The mesial aspect of this tooth has a distinctive concavity in the cervical third that extends onto the root. It is called variously the mesial developmental depression, mesial concavity, or the 'canine fossa'--a misleading description since it is on the premolar. The distal aspect of the maxillary first permanent molar also has a developmental depression. The mesial marginal developmental groove is a distinctive feature of this tooth.
Occlusal: There are two well-defined cusps buccal and lingual. The larger cusp is the buccal; its cusp tip is located midway mesiodistally. The lingual cusp tip is shifted mesially. The occlusal outline presents a hexagonal appearance. On the mesial marginal ridge is a distinctive feature, the mesial marginal developmental groove.
Contact Points;The distal contact area is located more buccal than is the mesial contact area.
Root Surface:-The root is quite flat on the mesial and distal surfaces. In about 50 percent of maxillary first bicuspids, the root is divided in the apical third, and when it so divided, the tips of the facial and lingual roots are slender and finely tapered.
Topical Anesthetics
Pharmacology
Topical Anesthetics
Benzocaine
Benzocaine is a derivative of procaine, an ester type local anesthetic, and is poorly soluble in water and is
available only as a topical anesthetic.
- Localized allergic reactions are sometimes encountered
- Overdosing is unlikely as benzocaine is poorly absorbed into the blood, which decreases the likelihood of systemic toxicity.
- The onset of surface anesthesia is rapid requiring less than one minute.
Tetracaine
- Tetracaine is an ester type local anesthetic
- Topically applied tetracaine as opposed to benzocaine has a prolonged duration of action.
Cocaine
- Cocaine is a ester type anesthetic that is used exclusively as a topical agent.
- Cocaine is unique among topical and injectable anesthetics in that it has vasoconstrictive as well as anesthetic properties. It is used sparingly because of its abuse potential but is still used when hemostasis of mucous membranes is essential.
- Cocaine is generally available in concentrations of 2-10 % solution.
Lidocaine
- Lidocaine is an amide local anesthetic that is available in injectable and topical formulations.
- It is available in gel, viscous solution, ointment and aerosol preparations in concentrations ranging from 2-10 %.
- The onset of anesthesia is slower relative to benzocaine but, the duration is about the same.
- Absorption into the bloodstream is greater than benzocaine providing a greater risk of systemic toxicity.
AGE CHANGES of the Periodontal Ligament (PDL)
Dental Anatomy
AGE CHANGES
Progressive apical migration of the dentogingival junction.
Toothbrush abrasion of the area can expose dentin that can cause root caries and tooth mobility.
Histology of the alveolar bone
Near the end of the 2nd month of fetal life, mandible and maxilla form a groove that is opened toward the surface of the oral cavity.
As tooth germs start to develop, bony septa form gradually. The alveolar process starts developing strictly during tooth eruption.
The alveolar process is the bone that contains the sockets (alveoli) for the teeth and consists of
a) outer cortical plates
b) a central spongiosa and
c) bone lining the alveolus (bundle bone)
The alveolar crest is found 1.5-2.0 mm below the level of the CEJ.
If you draw a line connecting the CE junctions of adjacent teeth, this line should be parallel to the alveolar crest. If the line is not parallel, then there is high probability of periodontal disease.
Bundle Bone
The bundle bone provides attachment to the periodontal ligament fibers. It is perforated by many foramina that transmit nerves and vessels (cribiform plate). Embedded within the bone are the extrinsic fiber bundles of the PDL mineralized only at the periphery. Radiographically, the bundle bone is the lamina dura. The lining of the alveolus is fairly smooth in the young but rougher in the adults.
Clinical considerations
Resorption and regeneration of alveolar bone
This process can occur during orthodontic movement of teeth. Bone is resorbed on the side of pressure and opposed on the site of tension.
Osteoporosis
Osteoporosis of the alveolar process can be caused by inactivity of tooth that does not have an antagonist
Junctional Epithelium
PeriodontologyJunctional Epithelium
The junctional epithelium (JE) is a critical component of the periodontal
tissue, playing a vital role in the attachment of the gingiva to the tooth
surface. Understanding its structure, function, and development is essential for
comprehending periodontal health and disease.
Structure of the Junctional Epithelium
Composition:
The junctional epithelium consists of a collar-like band of stratified
squamous non-keratinized epithelium.
This type of epithelium is designed to provide a barrier while
allowing for some flexibility and permeability.
Layer Thickness:
In early life, the junctional epithelium is approximately 3-4
layers thick.
As a person ages, the number of epithelial layers can increase
significantly, reaching 10 to 20 layers in older
individuals.
This increase in thickness may be a response to various factors,
including mechanical stress and inflammation.
Length:
The length of the junctional epithelium typically ranges from 0.25
mm to 1.35 mm.
This length can vary based on individual anatomy and periodontal
health.
Development of the Junctional Epithelium
The junctional epithelium is formed by the confluence of the
oral epithelium and the reduced enamel epithelium during the
process of tooth eruption.
This fusion is crucial for establishing the attachment of the gingiva to
the tooth surface, creating a seal that helps protect the underlying
periodontal tissues from microbial invasion.
Function of the Junctional Epithelium
Barrier Function: The junctional epithelium serves as a
barrier between the oral cavity and the underlying periodontal tissues,
helping to prevent the entry of pathogens.
Attachment: It provides a strong attachment to the
tooth surface, which is essential for maintaining periodontal health.
Regenerative Capacity: The junctional epithelium has a
high turnover rate, allowing it to regenerate quickly in response to injury
or inflammation.
Clinical Relevance
Periodontal Disease: Changes in the structure and
function of the junctional epithelium can be indicative of periodontal
disease. For example, inflammation can lead to increased permeability and
loss of attachment.
Healing and Repair: Understanding the properties of the
junctional epithelium is important for developing effective treatments for
periodontal disease and for managing healing after periodontal surgery.
Spray Particles
Conservative DentistrySpray Particles in the Dental Operatory
1. Aerosols
Aerosols are composed of invisible particles that range in size from
approximately 5 micrometers (µm) to 50 micrometers (µm).
Characteristics
Suspension: Aerosols can remain suspended in the air
for extended periods, often for hours, depending on environmental
conditions.
Transmission of Infection: Because aerosols can carry
infectious agents, they pose a risk for the transmission of respiratory
infections, including those caused by bacteria and viruses.
Clinical Implications
Infection Control: Dental professionals must implement
appropriate infection control measures, such as the use of personal
protective equipment (PPE) and effective ventilation systems, to minimize
exposure to aerosols.
2. Mists
Mists are visible droplets that are larger than aerosols, typically estimated to
be around 50 micrometers (µm) in diameter.
Characteristics
Visibility: Mists can be seen in a beam of light,
making them distinguishable from aerosols.
Settling Time: Heavy mists tend to settle gradually
from the air within 5 to 15 minutes after being generated.
Clinical Implications
Infection Risk: Mists produced by patients with
respiratory infections, such as tuberculosis, can transmit pathogens. Dental
personnel should be cautious and use appropriate protective measures when
treating patients with known respiratory conditions.
3. Spatter
Spatter consists of larger particles, generally greater than 50 micrometers
(µm), and includes visible splashes.
Characteristics
Trajectory: Spatter has a distinct trajectory and
typically falls within 3 feet of the patient’s mouth.
Potential for Coating: Spatter can coat the face and
outer garments of dental personnel, increasing the risk of exposure to
infectious agents.
Clinical Implications
Infection Pathways: Spatter or splashing onto mucosal
surfaces is considered a potential route of infection for dental personnel,
particularly concerning blood-borne pathogens.
Protective Measures: The use of face shields, masks,
and protective clothing is essential to minimize the risk of exposure to
spatter during dental procedures.
4. Droplets
Droplets are larger than aerosols and mists, typically ranging from 5 to 100
micrometers in diameter. They are formed during procedures that involve the use
of water or saliva, such as ultrasonic scaling or high-speed handpieces.
Characteristics
Size and Behavior: Droplets can be visible and may
settle quickly due to their larger size. They can travel short distances but
are less likely to remain suspended in the air compared to aerosols.
Transmission of Pathogens: Droplets can carry
pathogens, particularly during procedures that generate saliva or blood.
Clinical Implications
Infection Control: Droplets can pose a risk for
respiratory infections, especially in procedures involving patients with
known infections. Proper PPE, including masks and face shields, is essential
to minimize exposure.
5. Dust Particles
Dust particles are tiny solid particles that can be generated from various
sources, including the wear of dental materials, the use of rotary instruments,
and the handling of dental products.
Characteristics
Size: Dust particles can vary in size but are generally
smaller than 10 micrometers in diameter.
Sources: They can originate from dental materials, such
as composite resins, ceramics, and metals, as well as from the environment.
Clinical Implications
Respiratory Risks: Inhalation of dust particles can
pose respiratory risks to dental personnel. Effective ventilation and the
use of masks can help reduce exposure.
Allergic Reactions: Some individuals may have allergic
reactions to specific dust particles, particularly those derived from dental
materials.
6. Bioaerosols
Bioaerosols are airborne particles that contain living organisms or
biological materials, including bacteria, viruses, fungi, and allergens.
Characteristics
Composition: Bioaerosols can include a mixture of
aerosols, droplets, and dust particles that carry viable microorganisms.
Sources: They can be generated during dental
procedures, particularly those that involve the manipulation of saliva,
blood, or infected tissues.
Clinical Implications
Infection Control: Bioaerosols pose a significant risk
for the transmission of infectious diseases. Implementing strict infection
control protocols, including the use of high-efficiency particulate air
(HEPA) filters and proper PPE, is crucial.
Monitoring Air Quality: Regular monitoring of air
quality in the dental operatory can help assess the presence of bioaerosols
and inform infection control practices.
7. Particulate Matter (PM)
Particulate matter (PM) refers to a mixture of solid particles and liquid
droplets suspended in the air. In the dental context, it can include a variety
of particles generated during procedures.
Characteristics
Size Categories: PM is often categorized by size,
including PM10 (particles with a diameter of 10 micrometers or less) and
PM2.5 (particles with a diameter of 2.5 micrometers or less).
Sources: In a dental setting, PM can originate from
dental materials, equipment wear, and environmental sources.
Clinical Implications
Health Risks: Exposure to particulate matter can have
adverse health effects, particularly for individuals with respiratory
conditions. Proper ventilation and air filtration systems can help mitigate
these risks.
Regulatory Standards: Dental practices may need to
adhere to local regulations regarding air quality and particulate matter
levels.