NEET MDS Synopsis
Post viral cirrhosis
General Pathology
Post viral (post hepatitic) cirrhosis (15-20%)
Cause:- Viral hepatitis (mostly HBV or HCV)
Acute hepatitis → chronic hepatitis → cirrhosis.
Pathology
Liver is shrunken. Fatty change is absent (except with HCV). Cirrhosis is mixed.
M/E :-
Hepatocytes-show degeneration, necrosis as other types of cirrhosis.
Fibrous septa -They are thick and immature (more cellular and vascular).
- Irregular margins (piece meal necrosis).
- Heavy lymphocytic infiltrate.
Prognosis:- - More rapid course than alcoholic cirrhosis.Hepatocellular carcinoma is more liable to occur
Stages of Development
PedodonticsStages of Development
Sensorimotor Stage (0-2 years):
Overview: In this stage, infants learn about the
world primarily through their senses and motor activities. They begin to
interact with their environment and develop basic cognitive skills.
Key Characteristics:
Object Permanence: Understanding that objects
continue to exist even when they cannot be seen.
Exploration: Infants engage in play by
manipulating objects, which helps them learn about cause and effect.
Symbolic Play: Even at this early stage,
children may begin to engage in simple forms of symbolic play, such
as pretending a block is a car.
Example in Dental Context: A child may play with
toys while sitting in the dental chair, exploring their environment and
becoming familiar with the setting.
Pre-operational Stage (2-6 years):
Overview: During this stage, children begin to use
language and engage in symbolic play, but their thinking is still
intuitive and egocentric. They struggle with understanding the
perspectives of others.
Key Characteristics:
Animism: The belief that inanimate objects have
feelings and intentions (e.g., thinking a toy can feel sad).
Constructivism: Children actively construct
their understanding of the world through experiences and
interactions.
Symbolic Play: Children engage in imaginative
play, using objects to represent other things (e.g., using a stick
as a sword).
Example: A child might pretend that a stuffed
animal is talking or has feelings, demonstrating animism.
Concrete Operational Stage (6-12 years):
Overview: In this stage, children begin to think
logically about concrete events. They can perform operations and
understand the concept of conservation (the idea that quantity doesn’t
change even when its shape does).
Key Characteristics:
Ego-centrism: While children in this stage are
less egocentric than in the pre-operational stage, they may still
struggle to see things from perspectives other than their own.
Logical Thinking: Children can organize objects
into categories and understand relationships between them.
Conservation: Understanding that certain
properties (like volume or mass) remain the same despite changes in
form or appearance.
Example: A child may understand that pouring water
from a short, wide glass into a tall, narrow glass does not change the
amount of water.
Formal Operational Stage (11-15 years):
Overview: In this final stage, adolescents develop
the ability to think abstractly, reason logically, and use deductive
reasoning. They can consider hypothetical situations and think about
possibilities.
Key Characteristics:
Abstract Thinking: Ability to think about
concepts that are not directly tied to concrete objects (e.g.,
justice, freedom).
Hypothetical-Deductive Reasoning: Ability to
formulate hypotheses and systematically test them.
Metacognition: Awareness and understanding of
one’s own thought processes.
Example: An adolescent can discuss moral dilemmas
or scientific theories, considering various outcomes and implications.
The Palate
AnatomyThe Palate
The palate forms the arched roof of the mouth and the floor of the nasal cavities.
The palate consists of two regions: the anterior 2/3 or bony part, called the hard palate, and the mobile posterior 1/3 or fibromuscular part, known as the soft palate.
The Tongue
AnatomyThe Tongue
The tongue (L. lingua; G. glossa) is a highly mobile muscular organ that can vary greatly in shape.
It consists of three parts, a root, body, and tip.
The tongue is concerned with mastication, taste, deglutition (swallowing), articulation (speech), and oral cleansing.
Its main functions are squeezing food into the pharynx when swallowing, and forming words during speech.
Gross Features of the Tongue
The dorsum of the tongue is divided by a V-shaped sulcus terminalis into anterior oral (presulcal) and posterior pharyngeal (postsulcal) parts.
The apex of the V is posterior and the two limbs diverge anteriorly.
The oral part forms about 2/3 of the tongue and the pharyngeal part forms about 1/3.
Oral Part of the Tongue
This part is freely movable, but it is loosely attached to the floor of the mouth by the lingual frenulum.
On each side of the frenulum is a deep lingual vein, visible as a blue line.
It begins at the tip of the tongue and runs posteriorly.
All the veins on one side of the tongue unite at the posterior border of the hyoglossus muscle to form the lingual vein, which joins the facial vein or the internal jugular vein.
On the dorsum of the oral part of the tongue is a median groove.
This groove represents the site of fusion of the distal tongue buds during embryonic development.
The Lingual Papillae and Taste Buds
The filiform papillae (L. filum, thread) are numerous, rough, and thread-like.
They are arranged in rows parallel to the sulcus terminalis.
The fungiform papillae are small and mushroom-shaped.
They usually appear are pink or red spots.
The vallate (circumvallate) papillae are surrounded by a deep, circular trench (trough), the walls of which are studded with taste buds.
The foliate papillae are small lateral folds of lingual mucosa that are poorly formed in humans.
The vallate, foliate and most of the fungiform papillae contain taste receptors, which are located in the taste buds.
The Pharyngeal Part of the Tongue
This part lies posterior to the sulcus terminalis and palatoglossal arches.
Its mucous membrane has no papillae.
The underlying nodules of lymphoid tissue give this part of the tongue a cobblestone appearance.
The lymphoid nodules (lingual follicles) are collectively known as the lingual tonsil.
Enamel
Dental Anatomy
Enamel
Structural characteristics and microscopic features
a. Enamel rods or prisms
(1) Basic structural unit of enamel.
(2) Consists of tightly packed hydroxyapatite crystals. Hydroxyapatite crystals in enamel are four times larger and more tightly packed than hydroxyapatite found in other calcified
tissues (i.e., it is harder than bone).
(3) Each rod extends the entire thickness of enamel and is perpendicular to the dentinoenamel junction (DEJ).
b. Aprismatic enamel
(1) The thin outer layer of enamel found on the surface of newly erupted teeth.
(2) Consists of enamel crystals that are aligned perpendicular to the surface.
(3) It is aprismatic (i.e., prismless) and is more mineralized than the enamel beneath it.
(4) It results from the absence of Tomes processes on the ameloblasts during the final stages of enamel deposition.
c. Lines of Retzius (enamel striae)
(1) Microscopic features
(a) In longitudinal sections, they are observed as brown lines that extend from the DEJ to the
tooth surface.
(b) In transverse sections, they appear as dark, concentric rings similar to growth rings in a tree.
(2) The lines appear weekly during the formation of enamel.
(3) Although the cause of striae formation is unknown, the lines may represent appositional or incremental growth of enamel. They may also result from metabolic disturbances of ameloblasts.
(4) Neonatal line
(a) An accentuated, dark line of Retzius that results from the effect of physiological changes
on ameloblasts at birth.
(b) Found in all primary teeth and some cusps of permanent first molars.
d. Perikymata
(1) Lines of Retzius terminate on the tooth surface in shallow grooves known a perikymata.
(2) These grooves are usually lost through wear but may be observed on the surfaces of developing teeth or nonmasticatory surfaces of formed teeth.
e. Hunter-Schreger bands
(1) Enamel rods run in different directions. In longitudinal sections, these changes in direction result in a banding pattern known as HunterSchreger bands.
(2) These bands represent an optical phenomenon of enamel and consist of a series of alternating dark and light lines when the section is viewed with reflected or polarized
light.
f. Enamel tufts
(1) Consist of hypomineralized groups of enamel rods.
(2) They are observed as short, dark projections found near or at the DEJ.
(3) They have no known clinical significance.
g. Enamel lamellae
(1) Small, sheet-like cracks found on the surface of enamel that extend its entire thickness.
(2) Consist of hypocalcified enamel.
(3) The open crack may be filled with organic material from leftover enamel organ components, connective tissues of the developing tooth, or debris from the oral cavity.
(4) Both enamel tufts and lamellae may be likened to geological faults in mature enamel.
h. Enamel spindle
(1) Remnants of odontoblastic processes that become trapped after crossing the DEJ during the differentiation of ameloblasts.
(2) Spindles are more pronounced beneath the cusps or incisal edges of teeth (i.e., areas where occlusal stresses are the greatest).
Quad helix appliance
OrthodonticsQuad helix appliance is an orthodontic device used to expand
the upper arch of teeth. It is typically cemented to the molars and features a
U-shaped stainless steel wire with active helix springs, helping to correct
issues like crossbites, narrow jaws, and crowded teeth. ### Components of the
Quad Helix Appliance
Helix Springs:
The appliance contains two or four active helix springs that exert
gentle pressure to widen the dental arch.
Bands:
It is attached to the molars using bands, which provide a stable
anchor for the appliance.
Wire Framework:
Made from 38 mil stainless steel wire, the framework allows for
customization and adjustment by the orthodontist.
Functions of the Quad Helix Appliance
Arch Expansion:
The primary function is to gradually widen the upper arch, creating
more space for crowded teeth.
Correction of Crossbites:
It helps in correcting posterior crossbites, where the lower teeth
are positioned outside the upper teeth.
Molar Stabilization:
The appliance stabilizes the molars in their correct position during
treatment.
Indications for Use
Narrow Upper Jaw:
Ideal for patients with a constricted upper arch.
Crowded Teeth:
Used when there is insufficient space for teeth to align properly.
Class II and Class III Cases:
Effective in treating specific malocclusions that require arch
expansion.
Advantages of the Quad Helix Appliance
Non-Invasive:
It is a non-surgical option for expanding the dental arch.
Fixed Design:
As a fixed appliance, it does not rely on patient compliance for
activation.
Customizable:
The design allows for adjustments to meet individual patient needs.
Limitations of the Quad Helix Appliance
Initial Discomfort:
Patients may experience mild discomfort or pressure during the first
few weeks of use.
Oral Hygiene Challenges:
Maintaining oral hygiene can be more difficult, requiring diligent
cleaning around the appliance.
Adjustment Period:
It may take time for patients to adapt to speaking and swallowing
with the appliance in place.
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.
Growth Theories
PedodonticsGrowth Theories
Understanding the growth of craniofacial structures is crucial in
pedodontics, as it directly influences dental development, occlusion, and
treatment planning. Various growth theories have been proposed to explain the
mechanisms behind craniofacial growth, each with its own assumptions and
clinical implications.
Growth Theories Overview
1. Genetic Theory (Brodle, 1941)
Assumption: Genes control all aspects of growth.
Application: While genetic factors play a role,
external factors significantly modify growth, reducing the sole impact of
genetics. Inheritance is polygenic, influencing predispositions such as
Class III malocclusion.
2. Scott’s Hypothesis (1953)
Assumption: Cartilage has innate growth potential,
which is later replaced by bone.
Application:
Mandibular growth is likened to long bone growth, with the condyles
acting as diaphysis.
Recent studies suggest that condylar growth is primarily reactive
rather than innate.
Maxillary growth is attributed to the translation of the
nasomaxillary complex.
3. Sutural Dominance Theory (Sicher, 1955)
Assumption: Sutural connective tissue proliferation
leads to appositional growth.
Application:
Maxillary growth is explained by pressure from sutural growth.
Limitations include inability to explain:
Lack of growth in suture transplantation.
Growth in cleft palate cases.
Sutural responses to external influences.
4. Moss’s Functional Theory (1962)
Assumption: Functional matrices (capsular and
periosteal) control craniofacial growth, with bone responding passively.
Application:
Examples include excessive cranial vault growth in hydrocephalus
cases, illustrating the influence of functional matrices on bone growth.
5. Van Limborgh’s Theory (1970)
Assumption: Skeletal morphogenesis is influenced by:
Intrinsic genetic factors
Local epigenetic factors
General epigenetic factors
Local environmental factors
General environmental factors
Application:
Highlights the interaction between genetic and environmental
factors, emphasizing that muscle and soft tissue growth also has a
genetic component.
Predicting facial dimensions based on parental studies is limited
due to the polygenic and multifactorial nature of growth.
6. Petrovic’s Hypothesis (1974, Cybernetics)
Assumption: Primary cartilage growth is influenced by
differentiation of chondroblasts, while secondary cartilage has both direct
and indirect effects on growth.
Application:
Explains the action of functional appliances on the condyle.
The upper arch serves as a mold for the lower arch, facilitating
optimal occlusion.
7. Neurotropism (Behrents, 1976)
Assumption: Nerve impulses, through axoplasmic
transport, have direct growth potential and influence soft tissue growth
indirectly.
Application:
The effect of neurotropism on growth is reported to be negligible,
suggesting limited clinical implications.
Clinical Implications
Understanding these growth theories is essential for pediatric dentists in
several ways:
Diagnosis and Treatment Planning: Knowledge of growth
patterns aids in diagnosing malocclusions and planning orthodontic
interventions.
Timing of Interventions: Recognizing the stages of
growth can help in timing treatments such as extractions, space maintainers,
and orthodontic appliances.
Predicting Growth Outcomes: Awareness of genetic and
environmental influences can assist in predicting treatment outcomes and
managing patient expectations.