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NEET MDS Synopsis

Esophagus pathology
General Pathology

ESOPHAGUS Pathology

Congenital malformations 
1. A tracheoesophageal fistula (the most prevalent esophageal anomaly) occurs most commonly as an upper esophageal blind pouch with a fistula between the lower segment of the esophagus and the trachea. It is associated with hydramnios, congenital heart disease, and other gastrointestinal malformation. 

2. Esophageal atresia is associated with VATER syndrome (vertebra1 defects, anal atresia, tracheoesophageal fistula, and renal dysplasia)

3. Stenosis refers to a narrowed esophagus with a small lumen.  lt may be congenital or acquired, e.g., through trauma or inflammation. 

Inflammatory disorders 

Esophagitis 

most often involves the lower half of the esophagus.  Caused by the reflux of gastric contents (juices) into the lower esophagus. One of the most common GI disorders.

Clinical features. 

Patients experience substernal burning  associated with regurgitation, mild anemia, dysphagia,  hematemesis, and melena. Esophagitis may predispose to esophageal cancer. 

Etiology

- Reflux esophagitis is due to an incompetent lower esophageal sphincter that permits reflux of gastric juice into the lower esophagus. 
- Irritants such as citric acid, hot liquids, alcohol, smoking, corrosive chemicals, and certain drugs, such as tetracycline, may provoke inflammation. 
- Infectious etiologies include herpes, CMV, and C. albicans. The immunocompromised host is particularly susceptible to infectious esophagitis. 
Although chronic or severe reflux disease is uncommon, consequences of these conditions can lead to Barrett’s esophagus, development of a stricture, or hemorrhage.

Pathology

-Grossly, there is hyperemia, edema, inflammation, and superficial necrosis. 

Complications include ulceration, bleeding, stenosis, and squamous carcinoma. 


Treatment: diet control, antacids, and medications that decrease the production of gastric acid (e.g., H blockers).


Barrett's esophagus, 

gastric or intestinal columnar epithelium replaces normal squamous epithelium in response to  chronic reflux.- A complication of chronic gastroesophageal reflux disease.
- Histologic findings include the replacement of squamous epithelium with metaplastic columnar epithelium.
- Complications include increased incidence of esophageal adenocarcinoma, stricture formation, or hemorrhage (ulceration).

 Motor disorders. 

Normal motor function requires effective peristalsis and relaxation of the lower esophageal sphincter. 

Achalasia is a lack of relaxation of the lower esophageal sphincter (LES), which may be associated with aperistalsis of the esophagus and increased basal tone of the LES. 

Clinical features. Achalasia occurs most commonly between the ages of 30 and 50. Typical symptoms are dysphagia, regurgitation, aspiration, and chest pain. The lack of motility promotes stagnation and predisposes to carcinoma. 

Hiatal hernia is the herniation of the abdominal esophagus, the stomach, or both, through the esophageal hiatus in the  diaphragm.

Scleroderma is a collagen vascular disease, seen primarily in women, that causes subcutaneous fibrosis and widespread  degenerative changes. (A mild variant is known as CREST syndrome which stands for calcinosis. raynaud's phenomenon , esophageal dysfunction, sclerodactyly and telengectseia. esophagus is the most frequently involved region of the gastrointestinal tract.

Clinical features are mainly dysphagia and heartburn due to reflux oesophagitis caused by aperlistalsis and incompetent LES. 


Rings and webs 

1. Webs are mucosal folds in the upper esophagus above the aortic arch. 
2. Schatzki rings are mucosal rings at the squamocolumnarjunction below the aortic arch.
3. Plummer Vinson Syndrome consist of triad of dysphagia, atrophic glossitis, and anemia. Webs are found in the upper esophagus. The syndrome is associated specifically with iron deficiency anemia and sometimes hypochlorhydria. Patients are at increased risk for carcinoma of the pharynx or esophagus. 

Mallory-Weiss syndrome
Mallory-Weiss tears refers to small mucosal tears at the gastroesophageal junction secondary to recurrent forceful vomiting. The tears occur along the long axis an result in hematemesis (sometimes massive).

- Characterized by lacerations (tears) in the esophagus.
- Most commonly occurs from vomiting (alcoholics).
- A related condition, known as Boerhaave syndrome, occurs when the esophagus ruptures, causing massive upper GI hemorrhage.

Esophageal varices
- The formation of varices (collateral channels) occurs from portal hypertension.
Causes of portal hypertension include blockage of the portal vein or liver disease (cirrhosis).
- Rupture of esophageal varices results in massive hemorrhage into the esophagus and hematemesis.
- Common in patients with liver cirrhosis.

Diverticula 
are sac-like protrusions of one or more layers of  pharyngeal or esophageal wall. 

Tumors 
- Benign tumors are rare. 
- Carcinoma of the esophagus most commonly occurs after 50 and has a male:female ratio of 4.1. 

Etiology: alcohal ingestion, smoking, nitrosamines in food, achalasia , web ring, Barrettes esophagus, and deficiencies of vitamins A and C , riboflavin, and some trace minerals

Clinical features include dysphagia (first to solids), retrosternal pain, anorexia, weight loss, melena, and symptoms secondary to metastases. 

Pathology 

- 50% occur in the middle third of the esophagus, 30% in the lower third, and 20% in the upper third. Most esophageal cancers are squamous cell carcinomas. 
Adenocarcinomas arise mostly out of Barrett's esophagus.

Prognosis

is poor. Fewer than 10% of patients survive 5 years, usually because diagnosis is made at a late stage. The  most common sites of metastasis are the liver and lung. The combination of cigarette smoking and alcohol is particularly causative for esophageal cancer (over l00%  risk compared to nondrinkers/nonsmokers). 

LAP and NUG
Periodontology

Localized Aggressive Periodontitis and Necrotizing Ulcerative Gingivitis
Localized Aggressive Periodontitis (LAP)
Localized aggressive periodontitis, previously known as localized juvenile
periodontitis, is characterized by specific microbial profiles and clinical
features.

Microbiota Composition:
The microbiota associated with LAP is predominantly composed of:
Gram-Negative, Capnophilic, and Anaerobic Rods.


Key Organisms:
Actinobacillus actinomycetemcomitans: The main
organism involved in LAP.
Other significant organisms include:
Porphyromonas gingivalis
Eikenella corrodens
Campylobacter rectus
Bacteroides capillus
Spirochetes (various species).




Viral Associations:
Herpes viruses, including Epstein-Barr Virus-1 (EBV-1) and Human
Cytomegalovirus (HCMV), have also been associated with LAP.






Necrotizing Ulcerative Gingivitis (NUG)

Microbial Profile:
NUG is characterized by high levels of:
Prevotella intermedia
Spirochetes (various species).




Clinical Features:
NUG presents with necrosis of the gingival tissue, pain, and
ulceration, often accompanied by systemic symptoms.




Microbial Shifts in Periodontal Disease
When comparing the microbiota across different states of periodontal health,
a distinct microbial shift can be identified as the disease progresses from
health to gingivitis to periodontitis:


From Gram-Positive to Gram-Negative:

Healthy gingival sites are predominantly colonized by gram-positive
bacteria, while diseased sites show an increase in gram-negative
bacteria.



From Cocci to Rods (and Later to Spirochetes):

In health, cocci (spherical bacteria) are prevalent. As the disease
progresses, there is a shift towards rod-shaped bacteria, and in
advanced stages, spirochetes become more prominent.



From Non-Motile to Motile Organisms:

Healthy sites are often dominated by non-motile bacteria, while
motile organisms increase in number as periodontal disease develops.



From Facultative Anaerobes to Obligate Anaerobes:

In health, facultative anaerobes (which can survive with or without
oxygen) are common. In contrast, obligate anaerobes (which thrive in the
absence of oxygen) become more prevalent in periodontal disease.



From Fermenting to Proteolytic Species:

The microbial community shifts from fermentative bacteria, which
primarily metabolize carbohydrates, to proteolytic species that break
down proteins, contributing to tissue destruction and inflammation.



Wrights Classification of Child Behavior
Pedodontics

Wright'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.



Parasympathetic Ganglia Of Head And Neck
Anatomy

Important parasympathetic ganglia in head and neck are :

(i) otic ganglion,
(ii) submandibular ganglion,
(iii) pterygopalatine ganglion
(iv) ciliary ganglion.

Otic Ganglion

Topographically, it is connected to mandibular nerve, while functionally it is related to glossopharyngeal (IX) nerve. Its roots are:-

Sensory root:-By Auriculotemporal nerve.

Sympathetic root:-By sympathetic plexus around middle meningeal artery.

Parasympathetic (secretomotor) root: - This root is by lesser petrosal nerve. Preganglionic fibres begin in inferior salivatory nucleus, pass through glossopharyngeal nerve, then its tympanic branch, tympanic plexus, and the lesser petrosal nerve and relay in otic ganglion.

Postganglionic fibers pass through auriculotemporal nerve and supplies parotid gland.

Motor root :- It is derived from nerve to medial pterygoid which passes unrelayed through ganglion and supplied tensor veli palatini and tensor tympani (Note :- Otic ganglion has a motor root, beside three standard roots of parasympathetic ganglion of head and neck: sensory, sympathetic and parasympathetic).

Submandibular Ganglion

Functionally, submandibular ganglion is connected to facial nerve, while topographically it is connected to lingual branch ofmandibular nerve. Its roots are :-

Sensory root: - It is from lingual nerve.

Sympathetic root: - It is from sympathetic plexus around facial artery, which contains postganglionic fibers from superior cervical ganglion of sympathetic trunk.

Secretomotor (parasympathetic) root: - Preganglionic fibers arise from superior salivatory nucleus pass through facial nerve then its chorda tympani branch which joins lingual nerve and relay in submandibular ganglion.

Postganglionic fibers supply :-Directly submandibulargland.
Through lingual nerveSublingual salivary gland and glands in oral cavity.

Pterygopalatine Ganglion (Sphenopalatine Ganglion)
 
It is the largest parasympathetic ganglion, suspended by two roots to maxillary nerve. Functionally, it is related to facial nerve. It is called ganglion of "hay fever". Its roots are:-

Sensory root:-It is from maxillary nerve.

Sympathetic root:-It is sympathetic plexus around internal carotid artery through deep petrosal nerve.

Secretomotor (parasympathetic) root:-Preganglionic fibers arise from lacrimatory nucleus, pass through facial nerve, then to its greater petrosal branch. Greater petrosal nerve unites with deep petrosal nerve (sympathetic fibers) to form nerve to pterygoid canal (Vidian nerve). Fibers reach to pterygopalatine ganglion; only fibers of greater petrosal nerve relay in the ganglion, not of deep petrosal nerve.
Postganglionic fibers supply lacrimal gland and palatal glands, and pharyngeal glands.

Branches of the pterygopalatine ganglion are :-

For lacrimal gland: - Postganglionic fibers pass through zygomatic nerve (branch of maxillary nerve), its zygomaticotemporal division which gives communicating branch to lacrimal nerve for supplying lacrimal gland.

Nasopalatine nerve:-For nasal and palatal glands.

Nasal branches: - For mucous membrane and glands oflateral wall of nasal cavity.

Palatine branches: - One greater palatine and 2-3 lesser palatine branches for glands of soft palate and hard palate.

Orbital branches: - For orbital periosteum.

Pharyngeal branches:-For glands of pharynx.

Ciliary Ganglion

Topographically, ciliary ganglion is related to nasociliary nerve (a branch of ophthalmic division of trigeminal nerve), but functionally it is related to oculomotor nerve. Its roots are:-

Sensory root:-It is from nasociliary nerve.

Sympathetic root: - It is from plexus around ophthalmic artery.

Parasympathetic root: - It is from a branch to inferior oblique muscle. These fibers arise from Edinger – Westphalnucleus, join oculomotor nerve and then to its branch to inferior oblique to relay in ciliary ganglion.

Postganglionic fibers pass through short ciliary nerves to supply sphincter pupillae and ciliary muscles.

Cytopathologic techniques
General Pathology

Cytopathologic techniques

Cytopathology is the study of cells from various body sites to determine the cause or nature of disease.

Applications of cytopathology:


Screening for the early detection of asymptomatic cancer


2. Diagnosis of symptomatic cancer

3. Surveillance of patients treated for cancer

Cytopathologic methods

There are different cytopathologic methods including:

1. Fine-needle aspiration cytology (FNAC) -In FNAC, cells are obtained by aspirating the diseased organ using a very thin needle under negative pressure.

Superficial organs (e.g. thyroid, breast, lymph nodes, skin and soft tissues) can be easily aspirated.

Deep organs, such as the lung, mediastinum, liver, pancreas, kidney, adrenal gland, and retroperitoneum are aspirated with guidance by fluoroscopy, ultrasound or CT scan.


Exfoliative cytology


Refers to the examination of cells that are shed spontaneously into body fluids or secretions. Examples include sputum, cerebrospinal fluid, urine, effusions in body cavities (pleura, pericardium, peritoneum), nipple discharge and vaginal discharge.


Abrasive cytology


Refers to methods by which cells are dislodged by various tools from body surfaces (skin, mucous membranes, and serous membranes). E.g. preparation of cervical smears with a spatula or a small brush to detect cancer of the uterine cervix at early stages.

Functional Matrix Hypothesis
Orthodontics

Functional Matrix Hypothesis is a concept in orthodontics
and craniofacial biology that explains how the growth and development of the
craniofacial complex (including the skull, face, and dental structures) are
influenced by functional demands and environmental factors rather than solely by
genetic factors. This hypothesis was proposed by Dr. Robert A. K.
McNamara and is based on the idea that the functional matrices—such as
muscles, soft tissues, and functional activities (like chewing and
speaking)—play a crucial role in shaping the skeletal structures.
Concepts of the Functional Matrix Hypothesis


Functional Matrices:

The hypothesis posits that the growth of the craniofacial skeleton
is guided by the functional matrices surrounding it. These matrices
include:
Muscles: The muscles of mastication, facial
expression, and other soft tissues exert forces on the bones,
influencing their growth and development.
Soft Tissues: The presence and tension of soft
tissues, such as the lips, cheeks, and tongue, can affect the
position and growth of the underlying skeletal structures.
Functional Activities: Activities such as
chewing, swallowing, and speaking create functional demands that
influence the growth patterns of the craniofacial complex.





Growth and Development:

According to the Functional Matrix Hypothesis, the growth of the
craniofacial skeleton is not a direct result of genetic programming but
is instead a response to the functional demands placed on it. This means
that changes in function can lead to changes in growth patterns.
For example, if a child has a habit of mouth breathing, the lack of
proper nasal function can lead to altered growth of the maxilla and
mandible, resulting in malocclusion or other dental issues.



Orthodontic Implications:

The Functional Matrix Hypothesis has significant implications for
orthodontic treatment and craniofacial orthopedics. It suggests that:
Functional Appliances: Orthodontic appliances
that modify function (such as functional appliances) can be used to
influence the growth of the jaws and improve occlusion.
Early Intervention: Early orthodontic
intervention may be beneficial in guiding the growth of the
craniofacial complex, especially in children, to prevent or correct
malocclusions.
Holistic Approach: Treatment should consider
not only the teeth and jaws but also the surrounding soft tissues
and functional activities.





Clinical Applications:

The Functional Matrix Hypothesis encourages clinicians to assess the
functional aspects of a patient's oral and facial structures when
planning treatment. This includes evaluating muscle function, soft
tissue relationships, and the impact of habits (such as thumb sucking or
mouth breathing) on growth and development.




Vertical angulations for child patient
Radiology


General guidelines for vertical angulations for common dental radiographs in
children:
Anterior Teeth

Maxillary Central Incisors:
Vertical Angulation: +40 to +50 degrees


Maxillary Lateral Incisors:
Vertical Angulation: +40 to +50 degrees


Maxillary Canines:
Vertical Angulation: +45 to +55 degrees


Mandibular Central Incisors:
Vertical Angulation: -10 to -20 degrees


Mandibular Lateral Incisors:
Vertical Angulation: -10 to -20 degrees


Mandibular Canines:
Vertical Angulation: -15 to -25 degrees



Posterior Teeth

Maxillary Premolars:
Vertical Angulation: +30 to +40 degrees


Maxillary Molars:
Vertical Angulation: +20 to +30 degrees


Mandibular Premolars:
Vertical Angulation: -5 to -10 degrees


Mandibular Molars:
Vertical Angulation: -5 to -10 degrees




Factors affecting onset and duration of action of local anesthetics
Pharmacology

Factors affecting onset and duration of action of local anesthetics

pH of tissue

pKa of drug

Time of diffusion from needle tip to nerve

Time of diffusion away from nerve

Nerve morphology

Concentration of drug

Lipid solubility of drug

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