NEET MDS Synopsis
Alzheimer’s disease
General Pathology
Alzheimer’s disease
a. The most common cause of dementia in older people.
b. Characterized by degeneration of neurons in the cerebral cortex.
c. Histologic findings include amyloid plaques and neurofibrillary tangles.
d. Clinically, the disease takes years to develop and results in the loss of cognition, memory, and the ability to ommunicate. Motor problems, contractures, and paralysis are some of the symptoms at the terminal stage.
Heart sounds
Physiology
Heart sounds
Heart sounds are a result of beating heart and resultant blood flow . that could be detected by a stethoscope during auscultation . Auscultation is a part of physical examination that doctors have to practice them perfectly.
Before discussion the origin and nature of the heart sounds we have to distinguish between the heart sounds and hurt murmurs. Heart murmurs are pathological noises that results from abnormal blood flow in the heart or blood vessels.
Physiologically , blood flow has a laminar pattern , which means that blood flows in form of layers , where the central layer is the most rapid . Laminar blood flow could be turned into turbulent one .
Turbulent blood flow is a result of stenotic ( narrowed ) valves or blood vessels , insufficient valves , roughened vessels` wall or endocardium , and many diseases . The turbulent blood flow causes noisy murmurs inside or outside the heart.
Heart sounds ( especially first and second sounds ) are mainly a result of closure of the valves of the heart . While the third sound is a result of vibration of ventricular wall and the leaflets of the opened AV valves after rapid inflow of blood from the atria to ventricles .
Third heart sound is physiologic in children but pathological in adults.
The four heart sound is a result of the atrial systole and vibration of the AV valves , due to blood rush during atrial systole . It is inaudible neither in adults nor in children . It is just detectable by the phonocardiogram .
Characteristic of heart sounds :
1. First heart sound (S1 , lub ) : a soft and low pitch sound, caused by closure of AV valves.Usually has two components ( M1( mitral ) and T1 ( tricuspid ). Normally M1 preceads T1.
2. Second heart sound ( S2 , dub) : sharp and high pitch sound . caused by closure of semilunar valves. It also has two components A2 ( aortic) and P2 ( pulmonary) . A2 preceads P2.
3. Third heart sound (S3) : low pitched sound.
4. Fourth heart sound ( S4) very low pitched sound.
As we notice : the first three sounds are related to ventricular activity , while the fourth heart sound is related to atrial activity.
Closure of valves is not the direct cause for heart sounds , but sharp blocking of blood of backward returning of blood by the closing valve is the direct cause.
Frenectomy and Frenotomy
Pedodontics
Frenectomy and Frenotomy
A frenectomy is
a surgical procedure that involves the complete excision of the frenum and its
periosteal attachment. This procedure is typically indicated when large, fleshy
frenums are present and may interfere with oral health or function.
Indications for Frenectomy
The decision to perform a frenectomy or frenotomy should be based on the ability
to maintain gingival health and the presence of specific clinical conditions.
The following are key indications for treating a high frenum:
Persistent Gingival Inflammation:
A high frenum attachment associated with an area of persistent gingival
inflammation that has not responded to root planing and good oral
hygiene practices.
Progressive Recession:
A frenum associated with an area of gingival recession that is
progressive, indicating that the frenum may be contributing to the loss
of attached gingiva.
Midline Diastema:
A high maxillary frenum that is associated with a midline diastema (gap
between the central incisors) that persists after the complete eruption
of the permanent canines.
Mandibular Lingual Frenum:
A mandibular lingual frenum that inhibits the tongue from making contact
with the maxillary central incisors, potentially interfering with the
child’s ability to articulate sounds such as /t/, /d/, and /l/.
If the child has sufficient range of motion to raise the tongue to the
roof of the mouth, surgery may not be indicated. Most children typically
develop the ability to produce these sounds after the age of 6 or 7, and
speech therapy may be recommended if issues persist.
Surgical Considerations
Keratinized Gingiva:
If a high frenum is associated with an area of no or minimal keratinized
gingiva, a vestibular extension or graft may be used to augment the
surgical procedure. This is important for ensuring stable long-term
results.
Frenotomy vs. Frenectomy:
In cases where a frenotomy or frenectomy does not create stable
long-term results, alternative approaches may be considered. Bohannan
indicated that if there is an adequate band of attached gingiva, high
frenums and vestibular depth do not pose significant problems.
Standard Approach:
The use of surgical procedures to eliminate the frenum pull is
considered a standard approach when indicated. The goal is to improve
gingival health and function while minimizing the risk of recurrence.
Drugs Used in Diabetes -Glitazones
Pharmacology
Glitazones (thiazolidinediones)
Thiazolidinediones, also known as the "-glitazones"
pioglitazone
rosiglitazone
Mechanism
bind to nuclear receptors involved in transcription of genes mediating insulin sensitivity
peroxisome proliferator-activating receptors (PPARs)
↑ insulin sensitivity in peripheral tissue
↓ gluconeogenesis
↑ insulin receptor numbers
↓ triglycerides
Clinical use
type II DM
as monotherapy or in combination with other agents
contraindicated in CHF
associated with increased risk of MI (in particular rosiglitazone)
Digit Sucking and Infantile Swallow
PedodonticsDigit Sucking and Infantile Swallow
Introduction to Digit Sucking
Digit sucking is a common behavior observed in infants and young children. It
can be categorized into two main types based on the underlying reasons for the
behavior:
Nutritive Sucking
Definition: This type of sucking occurs during
feeding and is essential for nourishment.
Timing: Nutritive sucking typically begins in the
first few weeks of life.
Causes: It is primarily associated with feeding
problems, where the infant may suck on fingers or digits as a substitute
for breastfeeding or bottle-feeding.
Non-Nutritive Sucking
Definition: This type of sucking is not related to
feeding and serves other psychological or emotional needs.
Causes: Non-nutritive sucking can arise from
various psychological factors, including:
Hunger
Satisfying the innate sucking instinct
Feelings of insecurity
Desire for attention
Examples: Common forms of non-nutritive sucking
habits include:
Thumb or finger sucking
Pacifier sucking
Non-Nutritive Sucking Habits (NMS Habits)
Characteristics: Non-nutritive sucking habits are often
comforting for children and can serve as a coping mechanism in stressful
situations.
Implications: While these habits are generally normal
in early childhood, prolonged non-nutritive sucking can lead to dental
issues, such as malocclusion or changes in the oral cavity.
Infantile Swallow
Definition: The infantile swallow is a specific pattern
of swallowing observed in infants.
Characteristics:
Active contraction of the lip musculature.
The tongue tip is positioned forward, making contact with the lower
lip.
Minimal activity of the posterior tongue and pharyngeal musculature.
Posture: The tongue-to-lower lip contact is so
prevalent in infants that it often becomes their resting posture. This can
be observed when gently moving the infant's lip, causing the tongue tip to
move in unison, suggesting a strong connection between the two.
Developmental Changes: The sucking reflex and the
infantile swallow typically diminish and disappear within the first year of
life as the child matures and develops more complex feeding and swallowing
patterns.
Spruing Technique
Dental Materials
I . Procedure for single casting :
A 2.5 mm sprue former is recommended
for molar crowns 2.0 mm for premolars & partial coverage crowns .
II . Procedure for multiple casting :
Each unit is joined to a runner bar .
A single sprue feeds the runner bar
4 . SPRUE FORMER DIRECTION
Sprue Should be directed away from the delicate parts of the pattern
It should not be at right angles to a flat surface .(leads to turbulance porosity .)
Ideal angulation is 45 degrees .
5 . SPRUE FORMER LENGTH
Depends on the length of casting ring .. Length of the Sprue former should be such that it keeps the wax pattern about 6 to 8 mm away from the casting ring. Sprue former should be no longer than 2 cm. The pattern should be placed as close to the centre of the ring as possible.
Significance
Short Sprue Length:
The gases cannot be adequately vented to permit the molten alloy to fill the ring completelyleading to Back Pressure Porosity.
Long Sprue Length:
Fracture of investment, as mold will not withstand the impact force of the entering molten alloy.
Top of wax should be adjusted for :
6 mm for gypsum bonded investments .
3 -4 mm for phosphate bonded investments .
TYPES OF SPRUES
I . - Wax . II . Solid
- Plastic . Hollow
- Metal .
Finger Rests in Dental Instrumentation
PeriodontologyFinger Rests in Dental Instrumentation
Use of finger rests is essential for providing stability and control during
procedures. A proper finger rest allows for more precise movements and reduces
the risk of hand fatigue.
Importance of Finger Rests
Stabilization: Finger rests serve to stabilize the hand
and the instrument, providing a firm fulcrum that enhances control during
procedures.
Precision: A stable finger rest allows for more
accurate instrumentation, which is crucial for effective treatment and
patient safety.
Reduced Fatigue: By providing support, finger rests
help reduce hand and wrist fatigue, allowing the clinician to work more
comfortably for extended periods.
Types of Finger Rests
Conventional Finger Rest:
Description: The finger rest is established on the
tooth surfaces immediately adjacent to the working area.
Application: This is the most common type of finger
rest, providing direct support for the hand while working on a specific
tooth. It allows for precise movements and control during
instrumentation.
Cross Arch Finger Rest:
Description: The finger rest is established on the
tooth surfaces on the other side of the same arch.
Application: This technique is useful when working
on teeth that are not directly adjacent to the finger rest. It provides
stability while allowing access to the working area from a different
angle.
Opposite Arch Finger Rest:
Description: The finger rest is established on the
tooth surfaces of the opposite arch (e.g., using a mandibular arch
finger rest for instrumentation on the maxillary arch).
Application: This type of finger rest is
particularly beneficial when accessing the maxillary teeth from the
mandibular arch, providing a stable fulcrum while maintaining visibility
and access.
Finger on Finger Rest:
Description: The finger rest is established on the
index finger or thumb of the non-operating hand.
Application: This technique is often used in areas
where traditional finger rests are difficult to establish, such as in
the posterior regions of the mouth. It allows for flexibility and
adaptability in positioning.
Rickets and Osteomalacia
General Pathology
Rickets and Osteomalacia
Rickets in growing children and osteomalacia in adults are skeletal diseases with worldwide distribution. They may result from
1. Diets deficient in calcium and vitamin D
2. Limited exposure to sunlight (in heavily veiled women, and inhabitants of northern climates with scant sunlight)
3. Renal disorders causing decreased synthesis of 1,25 (OH)2-D or phosphate depletion
4. Malabsorption disorders.
Although rickets and osteomalacia rarely occur outside high-risk groups, milder forms of vitamin D deficiency (also called vitamin D insufficiency) leading to bone loss and hip fractures are quite common in the elderly.
Whatever the basis, a deficiency of vitamin D tends to cause hypocalcemia. When hypocalcemia occurs, PTH production is increased, that ultimately leads to restoration of the serum level of calcium to near normal levels (through mobilization of Ca from bone & decrease in its tubular reabsorption) with persistent hypophosphatemia (through increase renal exretion of phosphate); so mineralization of bone is impaired or there is high bone turnover.
The basic derangement in both rickets and osteomalacia is an excess of unmineralized matrix. This complicated in rickets by derangement of endochondral bone growth.
The following sequence ensues in rickets:
1. Overgrowth of epiphyseal cartilage with distorted, irregular masses of cartilage
2. Deposition of osteoid matrix on inadequately mineralized cartilage
3. Disruption of the orderly replacement of cartilage by osteoid matrix, with enlargement and lateral expansion of the osteochondral junction
4. Microfractures and stresses of the inadequately mineralized, weak, poorly formed bone
5. Deformation of the skeleton due to the loss of structural rigidity of the developing bones
Gross features
• The gross skeletal changes depend on the severity of the disease; its duration, & the stresses to which individual bones are subjected.
• During the nonambulatory stage of infancy, the head and chest sustain the greatest stresses. The softened occipital bones may become flattened. An excess of osteoid produces frontal bossing. Deformation of the chest results from overgrowth of cartilage or osteoid tissue at the costochondral junction, producing the "rachitic rosary." The weakened metaphyseal areas of the ribs are subject to the pull of the respiratory muscles and thus bend inward, creating anterior protrusion of the sternum (pigeon breast deformity). The pelvis may become deformed.
• When an ambulating child develops rickets, deformities are likely to affect the spine, pelvis, and long bones (e.g., tibia), causing, most notably, lumbar lordosis and bowing of the legs .
• In adults the lack of vitamin D deranges the normal bone remodeling that occurs throughout life. The newly formed osteoid matrix laid down by osteoblasts is inadequately mineralized, thus producing the excess of persistent osteoid that is characteristic of osteomalacia. Although the contours of the bone are not affected, the bone is weak and vulnerable to gross fractures or microfractures, which are most likely to affect vertebral bodies and femoral necks.
Microscopic features
• The unmineralized osteoid can be visualized as a thickened layer of matrix (which stains pink in hematoxylin and eosin preparations) arranged about the more basophilic, normally mineralized trabeculae.