NEET MDS Synopsis
various X-ray projections
Radiology
1. Postero-Anterior (PA) View of Skull
Head Position: Centered in front of the cassette;
canthomeatal line parallel to the floor. For cephalometric applications, the
canthomeatal line is 10° above the horizontal, and the Frankfort plane is
perpendicular to the film.
Projection of Central Ray: Passes posterior to
anterior, perpendicular to the film.
Important Features:
Used to examine the skull for disease, trauma, and sinuses.
Best for viewing the coronoid process; a PA view with a 10° tilt is
called the Caldwell projection.
2. Lateral Skull or Cephalometric View
Head Position: Left side of the face near the cassette;
midsagittal plane parallel to the film.
Projection of Central Ray: Directed towards the
external auditory meatus, perpendicular to the film and midsagittal plane.
Important Features:
Assesses facial growth.
Reveals soft tissue profile.
Surveys skull and facial bones for disease and trauma.
3. Water's Projection
Head Position: Sagittal plane perpendicular to the
film; chin raised so the canthomeatal line is 37° above horizontal.
Projection of Central Ray: Passes through the maxillary
sinus.
Important Features:
Also known as Occipito-mental projection (variation of PA view).
Best for demonstrating zygoma fractures, paranasal sinuses, and
nasal cavity.
Shows the position of the coronoid process between the maxilla and
zygomatic arch.
4. Submentovertex (SMV) View
Head Position: Head and neck extended backward; vertex
of the skull at the center of the cassette.
Projection of Central Ray: Directed towards the vertex
of the skull.
Important Features:
Also called BASE, FULL AXIAL, or JUG HANDLE VIEW.
Best for viewing the base of the skull and zygomatic arch fractures.
Contraindicated in patients with cervical spondylitis.
For viewing zygomatic arches, exposure time is reduced to one-third
of that used for the skull.
5. Reverse Towne's View
Head Position: Canthomeatal line oriented 25-30°
downward.
Projection of Central Ray: Directed towards the
occipital bone.
Important Features:
Frankfort plane vertically oriented and parallel to the film.
Best for viewing condylar neck fractures.
Condyles are better visualized if the patient opens their mouth
widely.
6. Lateral Oblique Mandibular Body Projection
Head Position: Tilted towards the side being examined;
mandible protruded.
Projection of Central Ray: Directed towards the first
molar region.
Important Features:
Demonstrates the premolar and molar region.
Best for viewing the inferior border of the mandible.
7. Lateral Oblique Mandibular Ramus Projection
Head Position: Tilted towards the side being examined;
mandible protruded.
Projection of Central Ray: Directed posteriorly towards
the center of the ramus.
Important Features:
Often used for examining third molar regions of the maxilla and
mandible.
Provides a view of the ramus from the angle to the condyle.
Hypercementosis
PeriodontologyHypercementosis
Hypercementosis is a dental condition characterized by the excessive
deposition of cementum on the roots of teeth. This condition can have various
clinical implications and is associated with several underlying factors.
Understanding hypercementosis is essential for dental professionals in
diagnosing and managing related conditions.
Characteristics of Hypercementosis
Definition:
Hypercementosis is defined as a generalized thickening of the
cementum, often accompanied by nodular enlargement of the apical third
of the root. It can also manifest as spike-like excrescences known as
cemental spikes.
Forms of Hypercementosis:
Generalized Type: Involves a uniform thickening of
cementum across multiple teeth.
Localized Type: Characterized by nodular
enlargements or cemental spikes, which may result from:
Coalescence of cementicles adhering to the root.
Calcification of periodontal fibers at their insertion points
into the cementum.
Radiographic Appearance
Radiographic Features:
On radiographs, hypercementosis is identified by the presence of a
radiolucent shadow of the periodontal ligament and a radiopaque lamina
dura surrounding the area of hypercementosis, similar to normal
cementum.
Differentiation:
Hypercementosis can be differentiated from other conditions such
as periapical cemental dysplasia, condensing osteitis, and focal
periapical osteopetrosis, as these entities are located outside the
shadow of the periodontal ligament and lamina dura.
Etiology of Hypercementosis
Varied Etiology:
The exact cause of hypercementosis is not completely understood, but
several factors have been identified:
Spike-like Hypercementosis: Often results from
excessive tension due to orthodontic appliances or occlusal forces.
Generalized Hypercementosis: Can occur in
various circumstances, including:
Teeth Without Antagonists: In cases where
teeth lack opposing teeth, hypercementosis may develop as a
compensatory mechanism to keep pace with excessive tooth
eruption.
Low-Grade Periapical Irritation: Associated
with pulp disease, where hypercementosis serves as compensation
for the loss of fibrous attachment to the tooth.
Systemic Associations:
Hypercementosis may also be observed in systemic conditions,
including:
Paget’s Disease: Characterized by
hypercementosis of the entire dentition.
Other Conditions: Acromegaly, arthritis,
calcinosis, rheumatic fever, and thyroid goiter have also been
linked to hypercementosis.
Clinical Implications
Diagnosis:
Recognizing hypercementosis is important for accurate diagnosis and
treatment planning. Radiographic evaluation is essential for
distinguishing hypercementosis from other dental pathologies.
Management:
While hypercementosis itself may not require treatment, it can
complicate dental procedures such as extractions or endodontic
treatments. Understanding the condition can help clinicians anticipate
potential challenges.
Monitoring:
Regular monitoring of patients with known systemic conditions
associated with hypercementosis is important to manage any potential
complications.
Conductivity
Physiology
Conductivity :
Means ability of cardiac muscle to propagate electrical impulses through the entire heart ( from one part of the heart to another) by the excitatory -conductive system of the heart.
Excitatory conductive system of the heart involves:
1. Sinoatrial node ( SA node) : Here the initial impulses start and then conducted to the atria through the anterior inter-atrial pathway ( to the left atrium) , to the atrial muscle mass through the gap junction, and to the Atrioventricular node ( AV node ) through anterior, middle , and posterior inter-nodal pathways.
The average conductive velocity in the atria is 1m/s.
2- AV node : The electrical impulses can not be conducted directly from the atria to the ventricles , because of the fibrous skeleton , which is an electrical isolator , located between the atria and ventricles. So the only conductive way is the AV node . But there is a delay in the conduction occurs in the AV node .
This delay is due to:
- the smaller size of the nodal fiber.
- The less negative resting membrane potential
- fewer gap junctions.
There are three sites for delay:
- In the transitional fibers , that connect inter-nodal pathways with the AV node ( 0.03 ) .
- AV node itself ( 0.09 s) .
- In the penetrating portion of Bundle of Hiss ( 0.04 s) .
This delay actually allows atria to empty blood in ventricles during the cardiac cycle before the beginning of ventricular contraction , as it prevents the ventricles from the pathological high atrial rhythm.
The average velocity of conduction in the AV node is 0.02-0.05 m/s
3- Bundle of Hiss : A continuous with the AV node that passes to the ventricles through the inter-ventricular septum. It is subdivided into : Right and left bundle. The left bundle is also subdivided into two branches: anterior and posterior branches .
4- Purkinje`s fibers: large fibers with velocity of conduction 1.5-4 m/s.
the high velocity of these fibers is due to the abundant gap junctions , and to their nature as very large fibers as well.
The conduction from AV node is a one-way conduction . This prevents the re-entry of cardiac impulses from the ventricles to the atria.
Lastly: The conduction through the ventricular fibers has a velocity of 0.3-0.5 m/s.
Factors , affecting conductivity ( dromotropism) :
I. Positive dromotropic factors :
1. Sympathetic stimulation : it accelerates conduction and decrease AV delay .
2. Mild warming
3. mild hyperkalemia
4. mild ischemia
5. alkalosis
II. Negative dromotropic factors :
1. Parasympathetic stimulation
2. severe warming
3. cooling
4. Severe hyperkalemia
5. hypokalemia
6. Severe ischemia
7. acidosis
8. digitalis drugs.
Dental implications of antiepileptic drugs:
Pharmacology
Dental implications of these drugs:
1. Adverse effects: gingival hyperplasia (phenytoin), osteomalacia (phenytoin, Phenobarbital), blood dyscrasias (all but rare)
2. Drug interactions: additive CNS depression (anesthetics, anxiolytics, opioid analgesics), induction of hepatic microsomal enzymes (phenytoin, Phenobarbital, carbamazepine), plasma protein binding (phenytoin and valproic acid)
3. Seizure susceptibility: stress can → seizures
Viral infectious diseases
General Medicine
Chickenpox
Chickenpox is caused by the varicella-zoster virus (VZV), also known as human herpes virus 3 (HHV-3)
Chickenpox is highly infectious and spreads from person to person by direct contact or through the air from an infected person’s coughing or sneezing
A persons with chickenpox is contagious 1-2 days before the rash appears and until all blisters have formed scabs It takes 5- 10 days
0-21 days after contact with an infected person for someone to develop chickenpox
start as a 2-4 mm red papule which develops an irregular outline (rose petal).
A thin-walled, clear vesicle (dew drop) develops on top of the area of redness. This "dew drop on a rose petal" lesion is very characteristic for chicken pox
After about 8-12 hours the fluid in the vesicle gets cloudy and the vesicle breaks leaving a crust.
The fluid is highly contagious, but once the lesion crusts over, it is not considered contagious. The crust usually falls off after 7 days sometimes leaving a craterlike scar
Vaccination
Routine vaccination against varicella zoster virus has dramatically reduced the incidence of disease
Herpes simplex virus
The herpes simplex virus (HSV) (also known as Cold Sore, Night Fever, or Fever Blister) is a virus that manifests itself in two common viral infections, each marked by painful, watery blisters in the skin or mucous membranes (such as the mouth or lips) or on the genitals
the two most common are type 1 (HSV-1) and type 2 (HSV-2). HSV-1 is more common and generally considered to be associated with orofacial infection, usually the lips
HSV-2 is associated with the infection of the genitals, although both types can affect either region. HSV-2 infection is of particular concern because of the largely asymptomatic nature of the infection, and the shedding of infective virions even in asymptomatic individuals.
Orofacial infection
Prodromal symptoms
Skin appears irritated
Sore or cluster of fluid-filled blisters appear
Lesion begins to heal, usually without scarring
These infections usually occur on lips especially near the vermilion border. Rarely will a cold sore appear inside the mouth. The sores may appear to be either weeping or dry, and may resemble a pimple, insect bite, or lesion. Vesicles may also appear on the fingers, an infection called whitlow.
Genital infection
Prodromal symptoms
Sore appears
Lesion begins to heal, usually without scarring
In men, the lesions may occur on the shaft of the penis, in the genital region, on the inner thigh, buttocks, or anus. In women, lesions may occur on or near the pubis, labia, clitoris, vulva, buttocks, or anus
Treatments
antiviral medications for controlling herpes outbreaks, including acyclovir (Zovirax), valacyclovir (Valtrex), famcyclovir (Famvir), and pencyclovir
All drugs in this class depend on the activity of the viral thymidine kinase to convert the drug to a monophosphate form and subsequently interfere with viral DNA replication.
Pencyclovir's primary advantage over acyclovir is that it has a far longer cellular half-life
Docosanol works by preventing the virus from fusing to cell membranes, thus barring entry into the cell for the virus
Tromantadine is another antiviral drug effective against herpes.
Herpes zoster
Herpes zoster, colloquially known as shingles, is the reactivation of varicella zoster virus, leading to a crop of painful blisters over the area of a dermatome
Signs and symptoms
pain is the first symptom. This pain can be characterized as stinging, tingling, numbing, or throbbing, and can be pronounced with quick stabs of intensity.
Then 2-3 crops of red lesions develop, which gradually turn into small blisters filled with serous fluid.
Shingles blisters are unusual in that they only appear on one side of the body . That is because the chickenpox virus can remain dormant for decades, and does so inside the spinal column or a nerve fiber.
If it reactivates as shingles, it affects only a single nerve fiber, or ganglion, which can radiate to only one side of the body.
The blisters therefore only affect one area of the body and do not cross the midline
The rash and pain usually subside within 3 to 5 weeks. The most common chronic complication of herpes zoster is postherpetic neuralgia.
serious effects including partial facial paralysis (usually temporary), ear damage, or encephalitis may occur.
Shingles on the upper half of the face (the first branch of the trigeminal nerve) may result in eye damage
Treatment
Aciclovir (an antiviral drug) inhibits replication of the viral DNA, and is used both as prophylaxis (e.g. in patients with AIDS) and as therapy for herpes zoster.
Steroids are often given in severe cases
A vaccine called live attenuated Oka/Merck VZV that has been proven successful in preventing it
Influenza
Influenza, commonly known as the flu or the grippe, is a contagious disease of the upper airways and the lungs, caused by an RNA virus
Symptoms
The virus attacks the respiratory tract, is transmitted from person to person by saliva droplets expelled by coughing, and causes the following symptoms:
Fever
Headache
Fatigue/Sore joints (can be extreme)
Dry cough
Sore throat
Nasal congestion
Sneezing
Irritated eyes
Body aches
Extreme coldness
Treatment
get plenty of rest, drink a lot of liquids
acetaminophen to relieve the fever and muscle aches
Children and teenagers with flu symptoms (particularly fever) should avoid taking aspirin as taking aspirin in the presence of influenza infection (especially influenza type B) can lead to Reye syndrome, a rare but potentially fatal disease of the liver
Mumps
Mumps or epidemic parotitis is a viral disease of humans.
Caused by a paramyxovirus, and is spread from person to person by saliva droplets or direct contact
Symptoms
The more common symptoms of mumps are:
Swelling of the parotid gland (or parotitis) in >90% of patients.
Fever
Headache
Sore throat
Orchitis
A physical examination confirms the presence of the swollen glands
If there is uncertainty about the diagnosis, serology or a saliva test for the virus may be carried out.
Rubella
caused by the Rubella virus
Symptoms
swollen glands or lymph nodes (may persist for up to a week)
fever (rarely rises above 38 degrees Celsius [100.4 degrees Fahrenheit])
rash (Appears on the face and then spreads to the trunk and limbs. It appears as pink dots under the skin. It appears on the first or third day of the illness but it disappears after a few days with no staining or peeling of the skin)
Forchheimer's sign occurs in 20% of cases, and is characterized by small, red papules on the area of the soft palate flaking, dry skin
inflammation of the eyes
nasal congestion
joint pain and swelling
pain in the testicles
loss of appetite
headache
nerves become weak or numb (very rare)
rubella can cause congenital rubella syndrome in the fetus of an infected pregnant woman.
Treatment
No specific treatment
MMR Vaccine is effective prevention
Poliomyelitis
infantile paralysis, is a viral paralytic disease.
The causative agent, a virus called poliovirus (PV), enters the body orally, infecting the intestinal wall.
It may proceed to the blood stream and into the central nervous system causing muscle weakness and often paralysis
Meningitis
Meningitis is inflammation of the membranes (meninges) covering the brain and the spinal cord.
Symptms
The classical symptoms of meningitis are headache, neck stiffness and photophobia (intolerance of bright light); the trio is called meningism.
Fever and chills are often present, along with myalgia.
An altered state of consciousness or other neurological deficits may be present depending on the severity of the disease.
In meningococcal meningitis or septicaemia, a petechial rash may appear.
A lumbar puncture to obtain cerebrospinal fluid (CSF) is usually indicated to determine the cause and direct appropriate treatment.
Convulsions and hydrocephalus are known complications of meningitis.
Diagnosis
examination of the cerebrospinal fluid
In patients with focal neurological deficits or signs of increased intracranial pressure, a CT scan of the head
Treatment
a broad spectrum intravenous antibiotic should be started immediately , often a third generation cephalosporin
Corticosteroids to relieve brain pressure and swelling and to prevent hearing loss that is common in patients with Haemophilus influenza meningitis
anticonvulsants such as dilantin or phenytoin to prevent seizures and corticosteroids to reduce brain inflammation
Vaccinations against Haemophilus influenzae (Hib) have decreased early childhood meningitis.
The pH scale
Biochemistry
The pH scale
An acidic solution is one in which [H+ ] > [OH- ]
•In an acidic solution, [H+ ] > 10-7 , pH < 7.
•A basic solution is when [OH- ] > [H+ ].
•In a basic solution, [OH- ] > 10-7 , pOH < 7, and pH >7.
• When the pH = 7, the solution is neutral.
•Physiological pH range is 6.5 to 8.0
Wrights Classification of Child Behavior
PedodonticsWright's Classification of Child Behavior
Hysterical/Uncontrolled
Description: This behavior is often seen in
preschool children during their first dental visit. These children may
exhibit temper tantrums, crying, and an inability to control their
emotions. Their reactions can be intense and overwhelming, making it
challenging for dental professionals to proceed with treatment.
Defiant/Obstinate
Description: Children displaying defiant behavior
may refuse to cooperate or follow instructions. They may argue or resist
the dental team's efforts, making it difficult to conduct examinations
or procedures.
Timid/Shy
Description: Timid or shy children may be hesitant
to engage with the dental team. They might avoid eye contact, speak
softly, or cling to their parents. This behavior can stem from anxiety
or fear of the unfamiliar dental environment.
Stoic
Description: Stoic children may not outwardly
express their feelings, even in uncomfortable situations. This behavior
can be seen in spoiled or stubborn children, where their crying may be
characterized by a "siren-like" quality. They may appear calm but are
internally distressed.
Overprotective Child
Description: These children may exhibit clinginess
or anxiety, often due to overprotective parenting. They may be overly
reliant on their parents for comfort and reassurance, which can
complicate the dental visit.
Physically Abused Child
Description: Children who have experienced physical
abuse may display heightened anxiety, fear, or aggression in the dental
setting. Their behavior may be unpredictable, and they may react
strongly to perceived threats.
Whining Type
Description: Whining children may express
discomfort or displeasure through persistent complaints or whining. This
behavior can be a way to seek attention or express anxiety about the
dental visit.
Complaining Type
Description: Similar to whining, complaining
children vocalize their discomfort or dissatisfaction. They may
frequently express concerns about the procedure or the dental
environment.
Tense Cooperative
Description: These children are on the borderline
between positive and negative behavior. They may show some willingness
to cooperate but are visibly tense or anxious. Their cooperation may be
conditional, and they may require additional reassurance and support.
Warfarin
Pharmacology
Warfarin (Coumadin):
The most common oral anticoagulant.
It is only active in vivo.
Warfarin is almost completely bound to plasma proteins. -96% to 98% bound.
Warfarin is metabolized by the liver and excreted in the urine.
Coumarin anticoagulants pass the placental barrier and are secreted into the maternal milk.
Newborn infants are more sensitive to oral anticoagulants than are adults because of lower vitamin K levels and lower rates of metabolism.
Bleeding is the most common side effect and occurs most often from the mucous membranes of the gastrointestinal tract and the genitourinary tract.
Oral anticoagulants are contraindicated in:
• Conditions where active bleeding must be avoided, Vitamin K deficiency and severe
hepatic or renal disease, and where intensive salicylate therapy is required.