NEET MDS Synopsis
Public health Dentistry
Public Health Dentistry
Terms
Health—state of complete physical, mental, and social well-being where basic human needs are met. not merely the absence of disease or infirmity; free from disease or pain
Public health — science and art of preventing disease. prolonging life, and promoting physical and mental health and efficiency through organized community efforts
1. Public health is concerned with the aggregate health of a group, a community, a state, a nation. or a group of nations
2. Public health is people’s health
3. Concerned with four broad areas
a. Lifestyle and behavior
b. The environment
c. Human biology
d. The organization of health programs and systems
Dental public health—science and art of preventing and controlling dental diseases and promoting dental health through organized community efforts; that form of dental practice that serves the community as a patient rather than the individual; concerned with the dental education of the public, with applied dental research, and with the administration of group dental care programs. as well as the prevention and control of dental diseases on a community basis
Community health—same as public health full range of health services, environmental and personal, including major activities such as health education of the public and the social context of life as it affects the community; efforts that are organized to promote and restore the health and quality of life of the people
Community dental health services are directed to ward developing, reinforcing, and enhancing the oral health status of people either as individuals or collectively as groups and communities
NECROSIS
General Pathology
NECROSIS
Definition: Necrosis is defined as the morphologic changes caused by the progressive degradative
action of enzymes on the lethally injured cell.
These changes are due to
I. Autolysis and
2. Heterolysis.
The cellular changes of necrosis i.e. death of circumscribed group of cells in continuity with living tissues are similar to changes in tissues following somatic death, except that in the former, there is leucocytic infiltration in reaction to the dead cells and the lytic
enzymes partly come from the inflammatory cell also. (Heterolysis). Cell death occurs in the normal situation of cell turnover also and this is called apoptosis-single cellular dropout.
Nuclear changes in necrosis
As cytoplasmic changes are a feature of degeneration ,similarly nuclear changes are the hallmark of necrosis. These changes are:
(i) Pyknosis –condensation of chromatin
(ii) Karyorrhexis - fragmentation
(iii) Karyolysis - dissolution
Types of necrosis
(1) Coagulative necrosis: Seen in infarcts. The architectural outlines are maintained though structural details are lost. E.g, myocardial infarct.
(2) Caseous necrosis: A variant of coagulative necrosis seen in tuberculosis. The architecture is destroyed, resulting in an eosinophilic amorphous debris.
(3) Colliquative (liquifactive). Necrosis seen in Cerebral infarcts and suppurative necrosis.
Gangrenous necrosis: It is the necrosis with superadded putrefaction
May be:
a. dry - coagulative product.
b. Wet - when there is bacterial liquifaction.
Fat necrosis
May be:
a. Traumatic (as in breast and subcutaneous tissue).
b Enzymatic (as in pancreatitis). It shows inflammation of fat with formation of lipophages and giant cells.
This is often followed by deposition of calcium as calcium soaps.
Hyaline necrosis: Seen in skeletal muscles in typhoid and in liver ceIs in some forms of hepatitis.
Fibrinoid necrosis: In hypertension and in immune based diseases.
Indirect Porcelain Veneers
Conservative DentistryIndirect Porcelain Veneers: Etched Feldspathic Veneers
Indirect porcelain veneers, particularly etched porcelain veneers, are a
popular choice in cosmetic dentistry for enhancing the aesthetics of teeth. This
lecture will focus on the characteristics, bonding mechanisms, and clinical
considerations associated with etched feldspathic veneers.
Indirect Porcelain Veneers: These are thin shells of
porcelain that are custom-made in a dental laboratory and then bonded to the
facial surface of the teeth. They are used to improve the appearance of
teeth that are discolored, misaligned, or have surface irregularities.
Types of Porcelain Veneers
Feldspathic Porcelain: The most frequently used type of
porcelain for veneers is feldspathic porcelain. This material is known for
its excellent aesthetic properties, including translucency and color
matching with natural teeth.
Hydrofluoric Acid Etching
Etching with Hydrofluoric Acid: Feldspathic porcelain
veneers are typically etched with hydrofluoric acid before bonding. This
process creates a roughened surface on the porcelain, which enhances the
bonding area.
Surface Characteristics: The etching process increases
the surface area and creates micro-retentive features that improve the
mechanical interlocking between the porcelain and the resin bonding agent.
Resin-Bonding Mediums
High Bond Strengths: The etched porcelain can achieve
high bond strengths to the etched enamel through the use of resin-bonding
agents. These agents are designed to penetrate the micro-retentive surface
created by the etching process.
Bonding Process:
Surface Preparation: The porcelain surface is
etched with hydrofluoric acid, followed by thorough rinsing and drying.
Application of Bonding Agent: A resin bonding agent
is applied to the etched porcelain surface. This agent may contain
components that enhance adhesion to both the porcelain and the tooth
structure.
Curing: The bonding agent is cured, either
chemically or with a light-curing process, to achieve a strong bond
between the porcelain veneer and the tooth.
Importance of Enamel Etching
Etched Enamel: The enamel surface of the tooth is also
typically etched with phosphoric acid to enhance the bond between the resin
and the tooth structure. This dual etching process (both porcelain and
enamel) is crucial for achieving optimal bond strength.
Clinical Considerations
A. Indications for Use
Aesthetic Enhancements: Indirect porcelain veneers are
indicated for patients seeking aesthetic improvements, such as correcting
discoloration, closing gaps, or altering the shape of teeth.
Minimal Tooth Preparation: They require minimal tooth
preparation compared to crowns, preserving more of the natural tooth
structure.
B. Contraindications
Severe Tooth Wear: Patients with significant tooth wear
or structural damage may require alternative restorative options.
Bruxism: Patients with bruxism (teeth grinding) may not
be ideal candidates for porcelain veneers due to the potential for fracture.
C. Longevity and Maintenance
Durability: When properly bonded and maintained,
porcelain veneers can last many years. Regular dental check-ups are
essential to monitor the condition of the veneers and surrounding tooth
structure.
Oral Hygiene: Good oral hygiene practices are crucial
to prevent caries and periodontal disease, which can compromise the
longevity of the veneers.
Fanconi’s syndrome
General Pathology
Fanconi’s syndrome
Characterized by the failure of the proximal renal tubules to resorb amino acids, glucose, and phosphates.
May be inherited or acquired.
Clinical manifestations include
glycosuria, hyperphosphaturia, hypophosphatemia, aminoaciduria, and systemic acidosis.
Hypothalamic - Pituitary Drugs
Pharmacology
Hypothalamic - Pituitary Drugs
Somatropin
Growth hormone (GH) mimetic
Mechanism
agonist at GH receptors
increases production of insulin growth factor-1 (IGF-1)
Clinical use
GH deficiency
increase adult height for children with conditions associated with short stature
Turner syndrome
wasting in HIV infection
short bowel syndrome
Toxicity
scoliosis
edema
gynecomastia
increased CYP450 activity
Octreotide
Somatostatin mimetic
Mechanism
agonist at somatostatin receptors
Clinical use
acromegaly
carcinoid
gastrinoma
glucagonoma
acute esophageal variceal bleed
Toxicity
GI upset
gallstones
bradycardia
Oxytocin
Mechanism
agonist at oxytocin receptor
Clinical use
stimulation of labor
uterine contractions
control of uterine hemorrhage after delivery
stimulate milk letdown
Toxicity
fetal distress
abruptio placentae
uterine rupture
Desmopressin
ADH (vasopressin) mimetic
Mechanism
agonist at vasopressin V2 receptors
Clinical use
central (pituitary) diabetes insipidus
hemophilia A (factor VIII deficiency)
increases availability of factor VIII
von Willebrand disease
increases release of von Willebrand factor from endothelial cells
Toxicity
GI upset
headache
hyponatremia
allergic reaction
Osteonecrosis
General Pathology
Osteonecrosis (Avascular Necrosis)
Ischemic necrosis with resultant bone infarction occurs mostly due to fracture or after corticosteroid use. Microscopically, dead bon trabevulae (characterized by empty lacunae) are interspersed with areas of fat necrosis.
The cortex is usually not affected because of collateral blood supply; in subchondral infarcts, the overlying articular cartilage also remains viable because the synovial fluid can provide nutritional support. With time, osteoclasts can resorb many of the necrotic bony trabeculae; any dead bone fragments that remain act as scaffolds for new bone formation, a process called creeping substitution.
Symptoms depend on the size and location of injury. Subchondral infarcts often collapse and can lead to severe osteoarthritis.
Transpalatal Arch
OrthodonticsTranspalatal Arch (TPA) is an orthodontic appliance used
primarily in the upper arch to provide stability, maintain space, and facilitate
tooth movement. It is a fixed appliance that connects the maxillary molars
across the palate, and it is commonly used in various orthodontic treatments,
particularly in conjunction with other appliances.
Components of the Transpalatal Arch
Main Wire:
The TPA consists of a curved wire that spans the palate, typically
made of stainless steel or a similar material. The wire is shaped to fit
the contour of the palate and is usually 0.036 inches in diameter.
Attachments:
The ends of the wire are attached to the bands or brackets on the
maxillary molars. These attachments can be soldered or welded to the
bands, ensuring a secure connection.
Adjustment Mechanism:
Some TPAs may include loops or bends that can be adjusted to apply
specific forces to the teeth, allowing for controlled movement.
Functions of the Transpalatal Arch
Stabilization:
The TPA provides anchorage and stability to the posterior teeth,
preventing unwanted movement during orthodontic treatment. It helps
maintain the position of the molars and can prevent them from drifting.
Space Maintenance:
The TPA can be used to maintain space in the upper arch, especially
after the premature loss of primary molars or in cases of crowding.
Tooth Movement:
The appliance can facilitate the movement of teeth, particularly the
molars, by applying gentle forces. It can be used to correct crossbites
or to expand the arch.
Support for Other Appliances:
The TPA can serve as a support structure for other orthodontic
appliances, such as expanders or functional appliances, enhancing their
effectiveness.
Indications for Use
Space Maintenance: To hold space for permanent teeth
when primary teeth are lost prematurely.
Crossbite Correction: To help correct posterior
crossbites by repositioning the molars.
Arch Expansion: In conjunction with other appliances,
the TPA can assist in expanding the dental arch.
Stabilization During Treatment: To provide anchorage
and prevent unwanted movement of the molars during orthodontic treatment.
Advantages of the Transpalatal Arch
Fixed Appliance: Being a fixed appliance, the TPA does
not require patient compliance, ensuring consistent force application.
Versatility: The TPA can be used in various treatment
scenarios, making it a versatile tool in orthodontics.
Minimal Discomfort: Generally, the TPA is
well-tolerated by patients and does not cause significant discomfort.
Limitations of the Transpalatal Arch
Limited Movement: The TPA primarily affects the molars
and may not be effective for moving anterior teeth.
Adjustment Needs: While the TPA can be adjusted, it may
require periodic visits to the orthodontist for modifications.
Oral Hygiene: As with any fixed appliance, maintaining
oral hygiene can be more challenging, and patients must be diligent in their
oral care.
Skeletal Muscle:
Anatomy
Skeletal Muscle: 1-40 cm long fibres, 10- 60 µm thick, according to myoglobin content there are:
Red fibres: lots of myoglobin, many mitochondriam slow twitching - tire slowly
White fibres: less myoglobin, less mitochondria, fast twitching - tire quickly
Intermediate fibres:
mixture of 2 above
Most muscles have all three - in varying ratios
Structure of skeletal muscle:
Light Microscopy: Many nuclei - 35/mm, Nuclei are oval - situated peripheral, Dark and light bands
Electron Microscopy: Two types of myofilaments
Actin
- 5,6 nm
3 components:
-actin monomers,
-tropomyosin - 7 actin molecules long
- troponin
actin monomers form 2 threats that spiral
- tropomyosin - lie in the groove of the spiral
- troponin - attach every 40 nm
- one end attach to the Z line
- other end goes to the middle of the sarcomere
- Z line consists of á actinin
Myosin:
- 15 nm
- 1,6 µm long
- The molecule has a head and a tail
- tails are parallel
- heads project in a spiral
- in the middle is a thickening
- thin threats bind the myosin at thickening (M line)
Contraction:
A - band stays the same, I - band, H - bands become narrower
Myosin heads ratchet on the actin molecule
Sarcolemma: 9 nm thick, invaginate to form T-tubule,
myofibrils - attach to the sarcolemma
Sarcoplasmic Reticulum:
specialized smooth EPR, Consists of T-tubules, terminal sisternae and sarcotubules
It is speculated that there are gap junctions between the T-tubule and terminal sisterna
An impulse is carried into the fiber by the T-tubule from where it goes to the rest of the sarcoplasmic reticulum
Connective tissue coverings of the muscle
Endomycium around fibres, perimycium around bundles and epimycium around the whole muscle
Blood vessels and nerves in CT
CT goes over into tendon or aponeurosis which attaches to the periosteum
Nerves:
The axon of a motor neuron branches and ends in motor end plates on the fiber
Specialized striated fibres called spindles (stretch receptors) form sensory receptors in muscles telling the brain how far the muscle has stretched