NEET MDS Synopsis
The Protein Buffer Systems
Biochemistry
The Protein Buffer Systems
The protein buffers are very important in the plasma and the intracellular fluids but their concentration is very low in cerebrospinal fluid, lymph and interstitial fluids.
The proteins exist as anions serving as conjugate bases (Pr − ) at the blood pH 7.4 and form conjugate acids (HPr) accepting H+ . They have the capacity to buffer some H2CO3 in the blood.
Hydromorphone
Pharmacology
Hydromorphone
About 8-10 times more potent than morphine when given intravenously.
Slightly shorter duration of action.
More soluble than morphine, thus higher concentrations may be injected if necessary.
Better oral/parenteral absorption ratio than morphine, but not as good as codeine or oxycodone.
It is used for the treatment of moderate to severe pain
Cariogram
Conservative DentistryCariogram: A Visual Tool for Understanding Caries Risk
The Cariogram is a graphical representation developed by Brathall et al. in
1999 to illustrate the interaction of various factors contributing to the
development of dental caries. This tool helps dental professionals and patients
understand the multifactorial nature of caries and assess individual risk
levels.
1. Overview of the Cariogram
Purpose: The Cariogram visually represents the
interplay between different factors that influence caries development,
allowing for a comprehensive assessment of an individual's caries risk.
Structure: The Cariogram is depicted as a pie chart
divided into five distinct sectors, each representing a specific
contributing factor.
2. Sectors of the Cariogram
A. Green Sector: Chance to Avoid Caries
Description: This sector estimates the likelihood of
avoiding caries based on the individual's overall risk profile.
Significance: A larger green area indicates a higher
chance of avoiding caries, reflecting effective preventive measures and good
oral hygiene practices.
B. Dark Blue Sector: Diet
Description: This sector assesses dietary factors,
including the content and frequency of sugar consumption.
Components: It considers both the types of foods
consumed (e.g., sugary snacks, acidic beverages) and how often they are
eaten.
Significance: A smaller dark blue area suggests a diet
that is less conducive to caries development, while a larger area indicates
a higher risk due to frequent sugar intake.
C. Red Sector: Bacteria
Description: This sector evaluates the bacterial load
in the mouth, particularly focusing on the amount of plaque and the presence
of Streptococcus mutans.
Components: It takes into account the quantity of
plaque accumulation and the specific types of bacteria present.
Significance: A larger red area indicates a higher
bacterial presence, which correlates with an increased risk of caries.
D. Light Blue Sector: Susceptibility
Description: This sector reflects the individual's
susceptibility to caries, influenced by factors such as fluoride exposure,
saliva secretion, and saliva buffering capacity.
Components: It considers the effectiveness of fluoride
programs, the volume of saliva produced, and the saliva's ability to
neutralize acids.
Significance: A larger light blue area suggests greater
susceptibility to caries, while a smaller area indicates protective factors
are in place.
E. Yellow Sector: Circumstances
Description: This sector encompasses the individual's
past caries experience and any related health conditions that may affect
caries risk.
Components: It includes the history of previous caries,
dental treatments, and systemic diseases that may influence oral health.
Significance: A larger yellow area indicates a higher
risk based on past experiences and health conditions, while a smaller area
suggests a more favorable history.
3. Clinical Implications of the Cariogram
A. Personalized Risk Assessment
The Cariogram provides a visual and intuitive way to assess an
individual's caries risk, allowing for tailored preventive strategies based
on specific factors.
B. Patient Education
By using the Cariogram, dental professionals can effectively communicate
the multifactorial nature of caries to patients, helping them understand how
their diet, oral hygiene, and other factors contribute to their risk.
C. Targeted Interventions
The information derived from the Cariogram can guide dental
professionals in developing targeted interventions, such as dietary
counseling, fluoride treatments, and improved oral hygiene practices.
D. Monitoring Progress
The Cariogram can be used over time to monitor changes in an
individual's caries risk profile, allowing for adjustments in preventive
strategies as needed.
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.
TEMPOROMANDIBULAR JOINT -ARTICULAR SURFACES COVERED BY FIBROUS TISSUE
Dental Anatomy
ARTICULAR SURFACES COVERED BY FIBROUS TISSUE
TMJ is an exception form other synovial joints. Two other joints, the acromio- and sternoclavicular joints are similar to the TMJ. Mandible & clavicle derive from intramembranous ossificiation.
Histologic
Fibrous layer: collagen type I, avascular (self-contained and replicating)
Proliferating zone that formes condylar cartilage
Condylar cartilage is fibrocartilage that does not play role in articulation nor has formal function
Capsule: dense collagenous tissue (includes the articular eminence)
Synovial membrane: lines capsule (does not cover disk except posterior region); contains folds (increase in pathologic conditions) and villi
Two layers: a cellular intima (synovial cells in fiber-free matrix) and a vascular subintima
Synovial cells: A (macrophage-like) syntesize hyaluronate
B (fibroblast-like) add protein in the fluid
Synovial fluid: plasma with mucin and proteins, cells
Liquid environment: lubrication, ?nutrition
Disk: separates the cavity into two comprartments, type I collagen
anterior and posterior portions
anetiorly it divides into two lamellae one towards the capsule, the other towards the condyle
vascular in the preiphery, avascular in the center
Ligaments: nonelastic collagenous structures. One ligament worth mentioning is the lateral or temporomandibular ligament. Also there are the spheno- and stylomandibular with debatable functional role.
Innervations
Ruffini
Posture
Dynamic and static balance
Pacini
Dynamic mechanoreception
Movement accelerator
Golgi
Static mechanoreception
Protection (ligament)
Free
Pain
Protection joint
Resistance Form in Dental Restorations
Conservative DentistryResistance Form in Dental Restorations
Resistance Form
A. Design Features
Flat Pulpal and Gingival Floors:
Flat surfaces provide stability and help distribute occlusal forces
evenly across the restoration, reducing the risk of displacement.
Box-Shaped Cavity:
A box-shaped preparation enhances resistance by providing a larger
surface area for bonding and mechanical retention.
Inclusion of Weakened Tooth Structure:
Including weakened areas in the preparation helps to prevent
fracture under masticatory forces by redistributing stress.
Rounded Internal Line Angles:
Rounding internal line angles reduces stress concentration points,
which can lead to failure of the restoration.
Adequate Thickness of Restorative Material:
Sufficient thickness is necessary to ensure that the restoration can
withstand occlusal forces without fracturing. The required thickness
varies depending on the type of restorative material used.
Cusp Reduction for Capping:
When indicated, reducing cusps helps to provide adequate support for
the restoration and prevents fracture.
B. Deepening of Pulpal Floor
Increased Bulk: Deepening the pulpal floor increases
the bulk of the restoration, enhancing its resistance to occlusal forces.
2. Features of Resistance Form
A. Box-Shaped Preparation
A box-shaped cavity preparation is essential for providing resistance
against displacement and fracture.
B. Flat Pulpal and Gingival Floors
These features help the tooth resist occlusal masticatory forces without
displacement.
C. Adequate Thickness of Restorative Material
The thickness of the restorative material should be sufficient to
prevent fracture of both the remaining tooth structure and the restoration.
For example:
High Copper Amalgam: Minimum thickness of 1.5 mm.
Cast Metal: Minimum thickness of 1.0 mm.
Porcelain: Minimum thickness of 2.0 mm.
Composite and Glass Ionomer: Typically require
thicknesses greater than 2.5 mm due to their wear potential.
D. Restriction of External Wall Extensions
Limiting the extensions of external walls helps maintain strong marginal
ridge areas with adequate dentin support.
E. Rounding of Internal Line Angles
This feature reduces stress concentration points, enhancing the overall
resistance form.
F. Consideration for Cusp Capping
Depending on the amount of remaining tooth structure, cusp capping may
be necessary to provide adequate support for the restoration.
3. Factors Affecting Resistance Form
A. Amount of Occlusal Stresses
The greater the occlusal forces, the more robust the resistance form
must be to prevent failure.
B. Type of Restoration Used
Different materials have varying requirements for thickness and design
to ensure adequate resistance.
C. Amount of Remaining Tooth Structure
The more remaining tooth structure, the better the support for the
restoration, which can enhance resistance form.
COMPLEMENT
General Microbiology
COMPLEMENT
The complement system primarily serves to fight bacterial infections.
The complement system can be activated by at least three separate pathways.
1) alternative pathway -
- The alternative pathway of complement activation starts with the spontaneous hydroysis of an internal thioester bond in the plasma complement component C3 to result in C3(H2O).
- The smaller cleavage products C3a, C4a, C5a, sometimes called "anaphylatoxins", act as phagocytes, they cause mast cell degranulation and enhance vessel permeability, thereby facilitating access of plasma proteins and leukocytes to the site of infection
- alternative pathway provides a means of non-specific resistance against infection without the participation of antibodies and hence provides a first line of defense against a number of infectious agents.
2) Lecithin Pathway
The lectin pathway of complement activation exploits the fact that many bacterial surfaces contain mannose sugar molecules in a characteristic spacing. The oligomeric plasma protein mannan-binding lectin (MBL; lectins are proteins binding sugars) binds to such a pattern of mannose moieties, activating proteases MASP-1 and MASP-2 (MASP=MBL activated serine protease, similar in structure to C1r and C1s). These, by cleaving C4 and C2, generate a second type of C3 convertase consisting of C4b and C2b, with ensuing events identical to those of the alternative pathway.
3) classical pathway
The classical pathway usually starts with antigen-bound antibodies recruiting the C1q component, followed by binding and sequential activation of C1r and C1s serine proteases. C1s cleaves C4 and C2, with C4b and C2b forming the C3 convertase of the classical pathway. Yet, this pathway can also be activated in the absence of antibodies by the plasma protein CRP (C-reactive protein), which binds to bacterial surfaces and is able to activate C1q.
Pharmacology cross reference: humanized monoclonal antibody Eculizumab binds to complement component C5, inhibiting its cleavage and preventing activation of the lytic pathway. This is desirable when unwanted complement activation causes hemolysis, as in paroxysmal nocturnal hemoglobinuria or in some forms of hemolytic uremic syndrome. For the lytic pathway's importance in fighting meningococcal infections, Eculizumab treatment increases the risk of these infections, which may be prevented by previous vaccination.
BIOLOGICALLY ACTIVE PRODUCTS OF COMPLEMENT ACTIVATION
Activation of complement results in the production of several biologically active molecules which contribute to resistance, anaphylaxis and inflammation.
Kinin production
C2b generated during the classical pathway of C activation is a prokinin which becomes biologically active following enzymatic alteration by plasmin. Excess C2b production is prevented by limiting C2 activation by C1 inhibitor (C1-INH) also known as serpin which displaces C1rs from the C1qrs complex (Figure 10). A genetic deficiency of C1-INH results in an overproduction of C2b and is the cause of hereditary angioneurotic edema. This condition can be treated with Danazol which promotes C1-INH production or with ε-amino caproic acid which decreases plasmin activity.
Anaphylotoxins
C4a, C3a and C5a (in increasing order of activity) are all anaphylotoxins which cause basophil/mast cell degranulation and smooth muscle contraction. Undesirable effects of these peptides are controlled by carboxypeptidase B (C3a-INA).
Chemotactic Factors
C5a and MAC (C5b67) are both chemotactic. C5a is also a potent activator of neutrophils, basophils and macrophages and causes induction of adhesion molecules on vascular endothelial cells.
Opsonins
C3b and C4b in the surface of microorganisms attach to C-receptor (CR1) on phagocytic cells and promote phagocytosis.
Other Biologically active products of C activation
Degradation products of C3 (iC3b, C3d and C3e) also bind to different cells by distinct receptors and modulate their functions.