NEET MDS Synopsis
MAXILLARY LATERAL INCISORS
Dental Anatomy
MAXILLARY LATERAL INCISORS
it is shorter, narrower, and thinner.
Facial: The maxillary lateral incisor resembles the central incisor, but is narrower mesio-distally. The mesial outline resembles the adjacent central incisor; the distal outline--and particularly the distal incisal angle is more rounded than the mesial incisal angle (which resembles that of the adjacent central incisor. The distal incisal angle resembling the mesial of the adjacent canine.
Lingual: On the lingual surface, the marginal ridges are usually prominent and terminate into a prominent cingulum. There is often a deep pit where the marginal ridges converge gingivally. A developmental groove often extends across the distal of the cingulum onto the root continuing for part or all of its length.
Proximal: In proximal view, the maxillary lateral incisor resembles the central except that the root appears longer--about 1 1/2 times longer than the crown. A line through the long axis of the tooth bisects the crown.
Incisal: In incisal view, this tooth can resemble either the central or the canine to varying degrees. The tooth is narrower mesiodistally than the upper central incisor; however, it is nearly as thick labiolingually.
Contact Points: The mesial contact is at the junction of the incisal third and the middle third. The distal contact is is located at the center of the middle third of the distal surface.
Root Surface:-The root is conical (cone-shaped) but somewhat flattened mesiodistally.
Anti-Diuretic Hormone Feedback
Physiology
An anti-diruetic is a substance that decreases urine volume, and ADH is the primary example of it within the body. ADH is a hormone secreted from the posterior pituitary gland in response to increased plasma osmolarity (i.e., increased ion concentration in the blood), which is generally due to an increased concentration of ions relative to the volume of plasma, or decreased plasma volume.
The increased plasma osmolarity is sensed by osmoreceptors in the hypothalamus, which will stimulate the posterior pituitary gland to release ADH. ADH will then act on the nephrons of the kidneys to cause a decrease in plasma osmolarity and an increase in urine osmolarity.
ADH increases the permeability to water of the distal convoluted tubule and collecting duct, which are normally impermeable to water. This effect causes increased water reabsorption and retention and decreases the volume of urine produced relative to its ion content.
After ADH acts on the nephron to decrease plasma osmolarity (and leads to increased blood volume) and increase urine osmolarity, the osmoreceptors in the hypothalamus will inactivate, and ADH secretion will end. Due to this response, ADH secretion is considered to be a form of negative feedback.
Cutting Edge Mechanics
Conservative DentistryCutting Edge Mechanics
Edge Angles and Their Importance
Edge Angle: The angle formed at the cutting edge of a
bur blade. Increasing the edge angle reinforces the cutting edge, which
helps to reduce the likelihood of blade fracture during use.
Reinforcement: A larger edge angle provides more
material at the cutting edge, enhancing its strength and durability.
Carbide vs. Steel Burs
Carbide Burs:
Hardness and Wear Resistance: Carbide burs are
known for their higher hardness and wear resistance compared to steel
burs. This makes them suitable for cutting through hard dental tissues.
Brittleness: However, carbide burs are more brittle
than steel burs, which means they are more prone to fracture if not
designed properly.
Edge Angles: To minimize the risk of fractures,
carbide burs require greater edge angles. This design consideration is
crucial for maintaining the integrity of the bur during clinical
procedures.
Interdependence of Angles
Three Angles: The cutting edge of a bur is defined by
three angles: the edge angle, the clearance angle, and the rake angle. These
angles cannot be varied independently of each other.
Clearance Angle: An increase in the clearance angle
(the angle between the cutting edge and the surface being cut) results
in a decrease in the edge angle. This relationship is important for
optimizing cutting efficiency and minimizing wear on the bur.
Induction Agents in Anesthesia
Oral and Maxillofacial SurgeryInduction Agents in Anesthesia
Propofol is a widely used intravenous anesthetic agent known
for its rapid onset and quick recovery profile, making it particularly suitable
for outpatient surgeries. It is favored for its ability to provide a
clear-headed recovery with a low incidence of postoperative nausea and vomiting.
Below is a summary of preferred induction agents for various clinical
situations, including the use of propofol and alternatives based on specific
patient needs.
Propofol
Use: Propofol is the agent of choice for most
outpatient surgeries due to its rapid onset and quick recovery time.
Advantages:
Provides a smooth induction and emergence from anesthesia.
Low incidence of nausea and vomiting, which is beneficial for
outpatient settings.
Allows for quick discharge of patients after surgery.
Preferred Induction Agents in Specific Conditions
Neonates:
Agent: Sevoflurane (Inhalation)
Rationale: Sevoflurane is preferred for induction
in neonates due to its rapid onset and minimal airway irritation. It is
well-tolerated and allows for smooth induction in this vulnerable
population.
Neurosurgery:
Agents: Isoflurane with Thiopentone/Propofol/Etomidate
Additional Consideration: Hyperventilation is often
employed to maintain arterial carbon dioxide tension (PaCO2) between 25-30
mm Hg. This helps to reduce intracranial pressure and improve
surgical conditions.
Rationale: Isoflurane is commonly used for its
neuroprotective properties, while thiopentone, propofol, or etomidate
can be used for induction based on the specific needs of the patient.
Coronary Artery Disease & Hypertension:
Agents: Barbiturates, Benzodiazepines,
Propofol, Etomidate
Rationale: All these agents are considered equally
safe for patients with coronary artery disease and hypertension. The
choice may depend on the specific clinical scenario, patient
comorbidities, and the desired depth of anesthesia.
Day Care Surgery:
Agent: Propofol
Rationale: Propofol is preferred for day care
surgeries due to its rapid recovery profile, allowing patients to be
discharged quickly after the procedure. Its low incidence of
postoperative nausea and vomiting further supports its use in outpatient
settings.
Roseola
General Pathology
Roseola
- alias exanthem subitum; caused by Herpes virus type 6.
- children 6 months to 2 years old; spring and fall; incubation 10-15 days.
- sudden onset of a high fever with absence of physical findings; febrile convulsions are particularly common.
- fever falls by crisis on the 3rd or 4th day → 48 hours after temperature returns to normal macular or maculopapular rash starting on the trunk and spreading centrifugally.
The Submandibular Glands
AnatomyThe Submandibular Glands
Each of these U-shaped salivary glands is about the size of a thumb and lies along the body of the mandible.
It is partly superior and partly inferior to the posterior 1/2 of the base of the mandible.
It is partly superficial and partly deep to the mylohyoid muscle.
The submandibular duct arises from the portion of the gland that lies between the mylohyoid and hyoglossus muscle.
The duct passes deep and then superficial to the lingual nerve.
It opens by one to three orifices on a small sublingual papilla beside the lingual frenulum.
The submandibular gland is supplied by parasympathetic, secretomotor fibres from the submandibular ganglion (preganglionic fibres from the chorda tympani via the lingual nerve).
Ketorolac
Pharmacology
Ketorolac
Mechanism of action
primary action responsible for its anti-inflammatory/antipyretic/analgesic effects is inhibition of prostaglandin synthesis through inhibition of the enzyme cyclooxygenase (COX). Ketorolac is not a selective inhibitor of COX enzymes
Indications: short-term management of pain
Contraindications
hypersensitivity to ketorolac, and against patients with the complete or partial syndrome of nasal polyps, angioedema, bronchospastic reactivity or other allergic manifestations to aspirin or other non-steroidal anti-inflammatory drugs (due to possibility of severe anaphylaxis).
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.