NEET MDS Synopsis
CARCINOMA IN SITU
General Pathology
CARCINOMA IN SITU
Epithelial malignancy which has not yet invaded even -the local confines viz basement membrane is termed as carcinoma in situ (intra epithelial neoplasia, pre-invasive cancer)
This lesion merges morphologically with severe dysplasia
Common sites for carcinoma-in-situ :
Cervical squamous epithelium
Oropharynx
Bronchial epithelium.
Breast ducts and lobules.
Skin, in the form of Bowen's disease.
Glans penis and vulva in the form of Erythroplasia of Queyrat
Sympatholytics And Alpha Adrenergic Blockers
Pharmacology
Sympatholytics And Alpha Adrenergic Blockers
Types
1. Alpha 1-receptor blockers: prazocin,doxazocin.
2. Centrally acting alpha 2- agonists: methyldopa, clonidine.
3. Peripherally acting adrenergic antagonists: reserpine.
4. Imidazoline receptor agonists: rilmenidine, moxonidine.
Advantages
- Alpha1- receptor blockers and imidazoline receptor agonists improve lipid profile and insulin sensitivity.
- Methyldopa: increases renal blood flow. Drug of choice during pregnancy.
- Reserpine: neutral metabolic effects and cheap.
Indications:
- Diabetes mellitus: alpha1- receptor blockers, imidazoline receptor agonists.
- Dyslipidemia: alpha 1- receptor blockers, imidazoline receptor agonists.
- Prostatic hypertrophy: alpha 1- receptor blockers.
- When there is a need for rapid reduction in blood pressure: clonidine.
Side Effects
- Prazocin: postural hypotension, diarrhea, occasional tachycardia, and tolerance (due to fluid retention).
- Methyldopa: sedation, hepatotoxicity, hemolytic anemia, and tolerance.
- Reserpine: depression, lethargy, weight loss, peptic ulcer, diarrhea, and impotence
- Clonidine: dry mouth, sedation, bradycardia, impotence, and rebound hypertension if stopped suddenly.
Considerations
- Prazocin, methyldopa, and reserpine should be combined with a diuretic because of fluid retention.
Direct Arterial Vasodilators
Types: hydralazine, diazoxide, nitroprusside, and minoxidil
Rotational Speeds of Dental Instruments
Conservative DentistryRotational Speeds of Dental Instruments
1. Measurement of Rotational Speed
Revolutions Per Minute (RPM)
Definition: The rotational speed of dental instruments
is measured in revolutions per minute (rpm), indicating how many complete
rotations the instrument makes in one minute.
Importance: Understanding the rpm is essential for
selecting the appropriate instrument for specific dental procedures, as
different speeds are suited for different tasks.
2. Speed Ranges of Dental Instruments
A. Low-Speed Instruments
Speed Range: Below 12,000 rpm.
Applications:
Finishing and Polishing: Low-speed handpieces are
commonly used for finishing and polishing restorations, as they provide
greater control and reduce the risk of overheating the tooth structure.
Cavity Preparation: They can also be used for
initial cavity preparation, especially in areas where precision is
required.
Instruments: Low-speed handpieces, contra-angle
attachments, and slow-speed burs.
B. Medium-Speed Instruments
Speed Range: 12,000 to 200,000 rpm.
Applications:
Cavity Preparation: Medium-speed handpieces are
often used for more aggressive cavity preparation and tooth reduction,
providing a balance between speed and control.
Crown Preparation: They are suitable for preparing
teeth for crowns and other restorations.
Instruments: Medium-speed handpieces and specific burs
designed for this speed range.
C. High-Speed Instruments
Speed Range: Above 200,000 rpm.
Applications:
Rapid Cutting: High-speed handpieces are primarily
used for cutting hard dental tissues, such as enamel and dentin, due to
their ability to remove material quickly and efficiently.
Cavity Preparation: They are commonly used for
cavity preparations, crown preparations, and other procedures requiring
rapid tooth reduction.
Instruments: High-speed handpieces and diamond burs,
which are designed to withstand the high speeds and provide effective
cutting.
3. Clinical Implications
A. Efficiency and Effectiveness
Material Removal: Higher speeds allow for faster
material removal, which can reduce chair time for patients and improve
workflow in the dental office.
Precision: Lower speeds provide greater control, which
is essential for delicate procedures and finishing work.
B. Heat Generation
Risk of Overheating: High-speed instruments can
generate significant heat, which may lead to pulpal damage if not managed
properly. Adequate cooling with water spray is essential during high-speed
procedures to prevent overheating of the tooth.
C. Instrument Selection
Choosing the Right Speed: Dentists must select the
appropriate speed based on the procedure being performed, the type of
material being cut, and the desired outcome. Understanding the
characteristics of each speed range helps in making informed decisions.
Impression Materials -Applications
Dental Materials
Applications
a. Dentulous impressions for casts for prosthodontics
b. Dentulous impressions for pedodontic appliances
c. Dentulous impressions for study models for orthodontics
d. Edentulous impressions for casts for denture construction
Mylohyoid Muscle
AnatomyMylohyoid Muscle
Origin: Mylohyoid line of the mandible.
Insertion: Median raphe and body of the hyoid bone.
Nerve Supply: Nerve to mylohyoid (branch of the
trigeminal nerve, CN V3).
Arterial Supply: Sublingual branch of the lingual
artery and submental branch of the facial artery.
Action: Elevates the hyoid bone, base of the tongue,
and floor of the mouth; depresses the mandible.
Hypopituitarism
General Pathology
Hypopituitarism
Hypopituitarism is caused by
1. Loss of the anterior pituitary parenchyma
a. congenital
b. acquired
2. Disorders of the hypothalamus e.g. tumors; these interfere with the delivery of pituitary hormone-releasing factors from the hypothalamus.
Most cases of anterior pituitary hypofunction are caused by the following:
1. Nonfunctioning pituitary adenomas
2. Ischemic necrosis of the anterior pituitary is an important cause of pituitary insufficiency. This requires destruction of 75% of the anterior pituitary.
Causes include
a. Sheehan syndrome, refers to postpartum necrosis of the anterior pituitary, and is the most cause. During pregnancy the anterior pituitary enlarges considerably because of an increase in the size and number of prolactin-secreting cells. However, this physiologic enlargement of the gland is not accompanied by an increase in blood supply. The enlarged gland is therefore vulnerable to ischemic injury, especially in women who develop significant hemorrhage and hypotension during the peripartum period. The posterior pituitary is usually not affected.
b. Disseminated intravascular coagulation
c. Sickle cell anemia
d. Elevated intracranial pressure
e. Traumatic injury
f. Shock states
3. Iatrogenic i.e. surgical removal or radiation-induced destruction
4. Inflammatory lesions such as sarcoidosis or tuberculosis
5. Metastatic neoplasms involving the pituitary.
6. Mutations affecting the pituitary transcription factor Pit-1
Children can develop growth failure (pituitary dwarfism) as a result of growth hormone deficiency.
Gonadotropin or gonadotropin-releasing hormone (GnRH) deficiency leads to amenorrhea and infertility in women and decreased libido, impotence, and loss of pubic and axillary hair in men. TSH and ACTH deficiencies result in symptoms of hypothyroidism and hypoadrenalism. Prolactin deficiency results in failure of postpartum lactation.
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.
Methods of general anesthesia
Pharmacology
Methods of general anesthesia
CIRCLE SYSTEM
*HIGH-FLOW
FRESH GAS FLOW > 3 l/min.
*LOW-FLOW
FGF ok. 1l/min.
*MINIMAL-FLOW
FGF ok. 0,5 l/min.