NEET MDS Synopsis
Causes of sudden loss of consciousness and collapse
General Medicine
• Simple faint
• Diabetic collapse secondary to hypoglycaemia
• Epileptic seizure
• Anaphylaxis
• Cardiac arrest
• Stroke
• Adrenal crisis
Distal Shoe Space Maintainer
PedodonticsDistal Shoe Space Maintainer
The distal shoe space maintainer is a fixed appliance used in pediatric
dentistry to maintain space in the dental arch following the early loss or
removal of a primary molar, particularly the second primary molar, before the
eruption of the first permanent molar. This appliance helps to guide the
eruption of the permanent molar into the correct position.
Indications
Early Loss of Second Primary Molar:
The primary indication for a distal shoe space maintainer is the
early loss or removal of the second primary molar prior to the eruption
of the first permanent molar.
It is particularly useful in the maxillary arch, where bilateral
space loss may necessitate the use of two appliances to maintain proper
arch form and space.
Contraindications
Inadequate Abutments:
The presence of multiple tooth losses may result in inadequate
abutments for the appliance, compromising its effectiveness.
Poor Patient/Parent Cooperation:
Lack of cooperation from the patient or parent can hinder the
successful use and maintenance of the appliance.
Congenitally Missing First Molar:
If the first permanent molar is congenitally missing, the distal
shoe may not be effective in maintaining space.
Medical Conditions:
Certain medical conditions, such as blood dyscrasias, congenital
heart disease (CHD), rheumatic fever, diabetes, or generalized
debilitation, may contraindicate the use of a distal shoe due to
increased risk of complications.
Limitations/Disadvantages
Overextension Risks:
If the distal shoe is overextended, it can cause injury to the
permanent tooth bud of the second premolar, potentially leading to
developmental issues.
Underextension Risks:
If the appliance is underextended, it may allow the molar to tip
into the space or over the band, compromising the intended space
maintenance.
Epithelialization Prevention:
The presence of the distal shoe may prevent complete
epithelialization of the extraction socket, which can affect healing.
Eruption Path Considerations:
Ronnermann and Thilander (1979) discussed the path of eruption,
noting that drifting of teeth occurs only after eruption through the
bone covering. The lower first molar typically erupts occlusally to
contact the distal crown surface of the primary molar, using that
contact for uprighting. Isolated cases of ectopic eruption should be
considered when evaluating the eruption path.
Enzyme Kinetics
Biochemistry
Enzyme Kinetics
Enzymes are protein catalysts that, like all catalysts, speed up the rate of a chemical reaction without being used up in the process. They achieve their effect by temporarily binding to the substrate and, in doing so, lowering the activation energy needed to convert it to a product.
The rate at which an enzyme works is influenced by several factors, e.g.,
the concentration of substrate molecules (the more of them available, the quicker the enzyme molecules collide and bind with them). The concentration of substrate is designated [S] and is expressed in unit of molarity.
the temperature. As the temperature rises, molecular motion - and hence collisions between enzyme and substrate - speed up. But as enzymes are proteins, there is an upper limit beyond which the enzyme becomes denatured and ineffective.
the presence of inhibitors.
competitive inhibitors are molecules that bind to the same site as the substrate - preventing the substrate from binding as they do so - but are not changed by the enzyme.
noncompetitive inhibitors are molecules that bind to some other site on the enzyme reducing its catalytic power.
pH. The conformation of a protein is influenced by pH and as enzyme activity is crucially dependent on its conformation, its activity is likewise affected.
The study of the rate at which an enzyme works is called enzyme kinetics.
HORMONES
Biochemistry
HORMONES
A hormone is a chemical that acts as a messenger transmitting a signal from one cell to another. When it binds to another cell which is the target of the message, the hormone can alter several aspects of cell function, including cell growth, metabolism, or other function.
Hormones can be classified on three primary ways as following:
1. Autocrine: An autocrine hormone is one that acts on the same cell that released it.
2. Paracrine: A paracrine hormone is one that acts on cells which are nearby relative to the cell which released it. An example of paracrine hormones includes growth factors, which are proteins that stimulate cellular proliferation and differentiation.
3. Endocrine: An endocrine hormone is one that is released into the bloodstream by endocrine glands. The receptor cells are distant from the source. An example of an endocrine hormone is insulin, which is released by the pancreas into the bloodstream where it regulates glucose uptake by liver and muscle cells.
Urine excretion
Physiology
Concentration versus diluting urine
Kidney is a major route for eliminating fluid from the body to accomplish water balance. Urine excretion is the last step in urine formation. Everyday both kidneys excrete about 1.5 liters of urine.
Depending on the hydrated status of the body, kidney either excretes concentrated urine ( if the plasma is hypertonic like in dehydrated status ) or diluted urine ( if the plasma is hypotonic) .
This occurs thankful to what is known as countercurrent multiplying system, which functions thankfully to establishing large vertical osmotic gradient .
To understand this system, lets review the following facts:
1. Descending limb of loop of Henle is avidly permeable to water.
2. Ascending limb of loop of Henly is permeable to electrolytes , but impermeable to water. So fluid will not folow electrolytes by osmosis.and thus Ascending limb creates hypertonic interstitium that will attract water from descending limb.
Pumping of electrolytes
3. So: There is a countercurrent flow produced by the close proximity of the two limbs.
Juxtamedullary nephrons have long loop of Henle that dips deep in the medulla , so the counter-current system is more obvious and the medullary interstitium is always hypertonic . In addition, peritubular capillaries in the medulla are straigh ( vasa recta) in which flow is rapid and rapidly reabsorb water maintaining hypertonic medullary interstitium.
In distal tubules water is diluted. If plasma is hypertonic, this will lead to release of ADH by hypothalamus, which will cause reabsorption of water in collecting tubules and thus excrete concentrated urine.
If plasma is hypotonic ADH will be inhibited and the diluted urine in distal tubules will be excreted as diluted urine.
Urea contributes to concentrating and diluting of urine as follows:
Urea is totally filtered and then 50% of filtrated urea will be reabsorbed to the interstitium, this will increase the osmolarity of medullary interstitium ( becomes hypertonic ). Those 50% will be secreted in ascending limb of loop of Henle back to tubular fluid to maintain osmolarity of tubular fluid. 55% of urea in distal nephron will be reabsorbed in collecting ducts back to the interstitium ( under the effect of ADH too) . This urea cycle additionally maintain hypertonic interstitium.
Oral Habits
PedodonticsClassification of Oral Habits
Oral habits can be classified based on various criteria, including their
nature, impact, and the underlying motivations for the behavior. Below is a
detailed classification of oral habits:
1. Based on Nature of the Habit
Obsessive Habits (Deep Rooted):
International or Meaningful:
Examples: Nail biting, digit sucking, lip biting.
Masochistic (Self-Inflicting):
Examples: Gingival stripping (damaging the gums).
Unintentional (Empty):
Examples: Abnormal pillowing, chin propping.
Non-Obsessive Habits (Easily Learned and Dropped):
Functional Habits:
Examples: Mouth breathing, tongue thrusting, bruxism (teeth
grinding).
2. Based on Impact
Useful Habits:
Habits that may have a positive or neutral effect on oral health.
Harmful Habits:
Habits that can lead to dental issues, such as malocclusion,
gingival damage, or tooth wear.
3. Based on Author Classifications
James (1923):
a) Useful Habits
b) Harmful Habits
Kingsley (1958):
a) Functional Oral Habits
b) Muscular Habits
c) Combined Habits
Morris and Bohanna (1969):
a) Pressure Habits
b) Non-Pressure Habits
c) Biting Habits
Klein (1971):
a) Empty Habits
b) Meaningful Habits
Finn (1987):
I. a) Compulsive Habits
b) Non-Compulsive Habits
II. a) Primary Habits
4. Based on Functionality
Functional Habits:
Habits that serve a purpose, such as aiding in speech or feeding.
Dysfunctional Habits:
Habits that disrupt normal oral function or lead to negative
consequences.
Microbes in Periodontics
PeriodontologyMicrobes in Periodontics
Bacteria Associated with Periodontal Health
Primary Species:
Gram-Positive Facultative Bacteria:
Streptococcus:
S. sanguis
S. mitis
A. viscosus
A. naeslundii
Actinomyces:
Beneficial for maintaining periodontal health.
Protective or Beneficial Bacteria:
Key Species:
S. sanguis
Veillonella parvula
Corynebacterium ochracea
Characteristics:
Found in higher numbers at inactive periodontal sites (no
attachment loss).
Low numbers at sites with active periodontal destruction.
Prevent colonization of pathogenic microorganisms (e.g., S.
sanguis produces peroxide).
Clinical Relevance:
High levels of C. ochracea and S. sanguis are
associated with greater attachment gain post-therapy.
Microbiology of Chronic Plaque-Induced Gingivitis
Composition:
Roughly equal proportions of:
Gram-Positive: 56%
Gram-Negative: 44%
Facultative: 59%
Anaerobic: 41%
Predominant Gram-Positive Species:
S. sanguis
S. mitis
S. intermedius
S. oralis
A. viscosus
A. naeslundii
Peptostreptococcus micros
Predominant Gram-Negative Species:
Fusobacterium nucleatum
Porphyromonas intermedia
Veillonella parvula
Haemophilus spp.
Capnocytophaga spp.
Campylobacter spp.
Pregnancy-Associated Gingivitis:
Increased levels of steroid hormones and P. intermedia.
Chronic Periodontitis
Key Microbial Species:
High levels of:
Porphyromonas gingivalis
Bacteroides forsythus
Porphyromonas intermedia
Campylobacter rectus
Eikenella corrodens
Fusobacterium nucleatum
Actinobacillus actinomycetemcomitans
Peptostreptococcus micros
Treponema spp.
Eubacterium spp.
Pathogenic Mechanisms:
P. gingivalis and A. actinomycetemcomitans can
invade host tissue cells.
Viruses such as Epstein-Barr Virus-1 (EBV-1) and human
cytomegalovirus (HCMV) may contribute to bone loss.
Localized Aggressive Periodontitis
Microbiota Characteristics:
Predominantly gram-negative, capnophilic, and anaerobic rods.
Almost all localized juvenile periodontitis (LJP) sites harbor A.
actinomycetemcomitans, which can comprise up to 90% of the total
cultivable microbiota.
Degrees of Mental Disability
PedodonticsDegrees of Mental Disability
Mental disabilities are often classified based on the severity of cognitive
impairment, which can be assessed using various intelligence scales, such as the
Wechsler Intelligence Scale and the Stanford-Binet Scale. Below is a detailed
overview of the degrees of mental disability, including IQ ranges and
communication abilities.
1. Mild Mental Disability
IQ Range: 55-69 (Wechsler Scale) or 52-67 (Stanford-Binet
Scale)
Description:
Individuals in this category may have some difficulty with academic
skills but can often learn basic academic and practical skills.
They typically can communicate well enough for most communication
needs and may function independently with some support.
They may have social skills that allow them to interact with peers
and participate in community activities.
2. Moderate Mental Disability
IQ Range: 40-54 (Wechsler Scale) or 36-51
(Stanford-Binet Scale)
Description:
Individuals with moderate mental disability may have significant
challenges in academic learning and require more support in daily
living.
Communication skills may be limited; they can communicate at a basic
level with others but may struggle with more complex language.
They often need assistance with personal care and may benefit from
structured environments and support.
3. Severe or Profound Mental Disability
IQ Range: 39 and below (Severe) or 35 and below
(Profound)
Description:
Individuals in this category have profound limitations in cognitive
functioning and adaptive behavior.
Communication may be very limited; some may be mute or communicate
only in grunts or very basic sounds.
They typically require extensive support for all aspects of daily
living, including personal care and communication.