NEET MDS Synopsis
Desquamative Gingivitis
PeriodontologyDesquamative Gingivitis
Characteristics: Desquamative gingivitis is
characterized by intense erythema, desquamation, and ulceration of both free
and attached gingiva.
Associated Diseases:
Lichen Planus
Pemphigus
Pemphigoid
Linear IgA Disease
Chronic Ulcerative Stomatitis
Epidermolysis Bullosa
Systemic Lupus Erythematosus (SLE)
Dermatitis Herpetiformis
Osteopetrosis
General Pathology
Osteopetrosis (Albers-Schönberg disease or marble bone disease)
is a group of rare genetic disorders characterized by reduced osteoclast-mediated bone resorption and therefore defective bone remodelling. The bones are solid and heavy with no medullary canal, long ends are bulbous, small neural foramina compress nerves. The affected bone is grossly dense but fractures occur readily like a piece of chalk.
Patients frequently have cranial nerve compressions by the surrouding bone, and recurrent infections. The latter is attributable to diminished hematopoiesis resulting from reduced marrow space with impressive hepatosplenomegaly due to extramedullary hematopoiesis
a. Caused by abnormal osteoclasts. This results in defective bone remodeling (i.e., abnormally low bone resorption) and increased bone density, which may invade into bone marrow space.
b. Causes severe defects in infants, including:
(1) Anemia and infections—caused by decreased bone marrow.
(2) Blindness, deafness, paralysis of facial muscles—caused by the narrowing of cranial nerve foramina.
(3) Is life-threatening.
(4) Oral findings include delayed eruption of teeth.
c. Disease is less severe in adults
Rocky Mountain Spotted Fever
General Pathology
Rocky Mountain Spotted Fever (Spotted Fever; Tick Fever; Tick Typhus)
An acute febrile disease caused by Rickettsia rickettsii and transmitted by ixodid ticks, producing high fever, cough, and rash.
Symptoms and Signs
The incubation period averages 7 days but varies from 3 to 12 days; the shorter the incubation period, the more severe the infection. Onset is abrupt, with severe headache, chills, prostration, and muscular pains. Fever reaches 39.5 or 40° C (103 or 104° F) within several days and remains high (for 15 to 20 days in severe cases),
Between the 1st and 6th day of fever, most patients develop a rash on the wrists, ankles, palms, soles, and forearms that rapidly extends to the neck, face, axilla, buttocks, and trunk. Often, a warm water or alcohol compress brings out the rash. Initially macular and pink, it becomes maculopapular and darker. In about 4 days, the lesions become petechial and may coalesce to form large hemorrhagic areas that later ulcerate
Neurologic symptoms include headache, restlessness, insomnia, delirium, and coma, all indicative of encephalitis. Hypotension develops in severe cases. Hepatomegaly may be present, but jaundice is infrequent. Localized pneumonitis may occur. Untreated patients may develop pneumonia, tissue necrosis, and circulatory failure, with such sequelae as brain and heart damage. Cardiac arrest with sudden death occasionally occurs in fulminant cases.
Danger Space
Oral and Maxillofacial SurgeryDanger Space: Anatomy and Clinical Significance
The danger space is an anatomical potential space located
between the alar fascia and the prevertebral fascia.
Understanding this space is crucial in the context of infections and their
potential spread within the neck and thoracic regions.
Anatomical Extent
Location: The danger space extends from the base
of the skull down to the posterior mediastinum,
reaching as far as the diaphragm. This extensive reach
makes it a significant pathway for the spread of infections.
Pathway for Infection Spread
Oropharyngeal Infections: Infections originating in the
oropharynx can spread to the danger space through the retropharyngeal
space. The retropharyngeal space is a potential space located
behind the pharynx and is clinically relevant in the context of infections,
particularly in children.
Connection to the Posterior Mediastinum: The danger
space is continuous with the posterior mediastinum, allowing for the
potential spread of infections from the neck to the thoracic cavity.
Mechanism of Infection Spread
Retropharyngeal Space: The spread of infection from the
retropharyngeal space to the danger space typically occurs at the junction
where the alar fascia and visceral fascia fuse,
particularly between the cervical vertebrae C6 and T4.
Rupture of Alar Fascia: Infection can spread by
rupturing through the alar fascia, which can lead to serious complications,
including mediastinitis, if the infection reaches the posterior mediastinum.
Clinical Implications
Infection Management: Awareness of the danger space is
critical for healthcare providers when evaluating and managing infections of
the head and neck. Prompt recognition and treatment of oropharyngeal
infections are essential to prevent their spread to the danger space and
beyond.
Surgical Considerations: Surgeons must be cautious
during procedures involving the neck to avoid inadvertently introducing
infections into the danger space or to recognize the potential for infection
spread during surgical interventions.
Clinical Signs and Their Significance
Oral and Maxillofacial SurgeryClinical Signs and Their Significance
Understanding various clinical signs is crucial for diagnosing specific
conditions and injuries. Below are descriptions of several important signs,
including Battle sign, Chvostek’s sign, Guerin’s sign, and Tinel’s sign, along
with their clinical implications.
1. Battle Sign
Description: Battle sign refers to ecchymosis
(bruising) in the mastoid region, typically behind the ear.
Clinical Significance: This sign is indicative of a
posterior basilar skull fracture. The bruising occurs due to the
extravasation of blood from the fracture site, which can be a sign of
significant head trauma. It is important to evaluate for other associated
injuries, such as intracranial hemorrhage.
2. Chvostek’s Sign
Description: Chvostek’s sign is characterized by the
twitching of the facial muscles in response to tapping over the area of the
facial nerve (typically in front of the ear).
Clinical Significance: This sign is often observed in
patients who are hypocalcemic (have low calcium levels). The twitching
indicates increased neuromuscular excitability due to low calcium levels,
which can lead to tetany and other complications. It is commonly assessed in
conditions such as hypoparathyroidism.
3. Guerin’s Sign
Description: Guerin’s sign is the presence of
ecchymosis along the posterior soft palate bilaterally.
Clinical Significance: This sign is indicative of
pterygoid plate disjunction or fracture. It suggests significant trauma to
the maxillofacial region, often associated with fractures of the skull base
or facial skeleton. The presence of bruising in this area can help in
diagnosing the extent of facial injuries.
4. Tinel’s Sign
Description: Tinel’s sign is a provocative test where
light percussion over a nerve elicits a distal tingling sensation.
Clinical Significance: This sign is often interpreted
as a sign of small fiber recovery in regenerating nerve sprouts. It is
commonly used in the assessment of nerve injuries, such as carpal tunnel
syndrome or after nerve repair surgeries. A positive Tinel’s sign indicates
that the nerve is healing and that sensory function may be returning.
Continuous Retention Groove Preparation
Conservative DentistryContinuous Retention Groove Preparation
Purpose and Technique
Retention Groove: A continuous retention groove is
prepared in the internal portion of the external walls of a cavity
preparation to enhance the retention of restorative materials, particularly
when maximum retention is anticipated.
Bur Selection: A No. ¼ round bur is used for this
procedure.
Location and Depth:
The groove is located 0.25 mm (half the diameter of the No. ¼ round
bur) from the root surface.
It is prepared to a depth of 0.25 mm, ensuring that it does not
compromise the integrity of the tooth structure.
Direction: The groove should be directed as the
bisector of the angle formed by the junction of the axial wall and the
external wall. This orientation maximizes the surface area for bonding and
retention.
Clinical Implications
Enhanced Retention: The continuous groove provides
additional mechanical retention, which is particularly beneficial in cases
where the cavity preparation is large or when the restorative material has a
tendency to dislodge.
Consideration of Tooth Structure: Care must be taken to
avoid excessive removal of tooth structure, which could compromise the
tooth's strength.
Bacterial Endocarditis
General Pathology
Bacterial endocarditis
Endocarditis is an infection of the endocardium of the heart, most often affecting the heart valves.
A. Acute endocarditis
1. Most commonly caused by Staphylococcus aureus.
2. It occurs most frequently in intravenous drug users, where it usually affects the tricuspid valve.
B. Subacute endocarditis
1. Most commonly caused by less virulent organisms, such as intraoral Streptococcus viridans that can be introduced systemically via dental procedures.
2. Pathogenesis: occurs when a thrombus or vegetation forms on a previously damaged or congenitally abnormal valve. These vegetations contain bacteria and inflammatory cells. Complications can arise if the thrombus embolizes, causing septic infarcts.
Other complications include valvular dysfunction or abscess formation.
3. Symptoms can remain hidden for months.
4. Valves affected (listed most to least common):
a. Mitral valve (most frequent).
b. Aortic valve.
c. Tricuspid (except in IV drug users, where the tricuspid valve is most often affected).
Halothane
Pharmacology
Halothane (Fluothane) MAC 0.76%, Blood/gas solubility ratio 2.3
- Nonflammable.
- Any depth of anesthesia can be obtained in the absence of hypoxia.
- Halothane produces a marked hypotensive effect
- accompanies hypotension.
- Halothane “sensitizes” the ventricular conduction system in the heart to the action of catecholamines. However, ventricular arrhythmias are rare if
- respiratory acidosis, hypoxia and other causes of sympathetic stimulation are avoided.
- Respiration is depressed by all anesthetic concentrations.
- Halothane is metabolized to a significant extent and some of its metabolic produces have been shown to be hepatotoxic.
- Can produce a malignant hyperpyrexia due to an uncontrolled hypermetabolic reaction in skeletal muscle.
Halothane is generally used with nitrous oxide, an opiate and a neuromuscular blocking drug.