NEET MDS Synopsis
THROMBOSIS
General Pathology
THROMBOSIS
Pathogenesis (called Virchow's triad):
1. Endothelial* Injury ( Heart, Arteries)
2. Stasis
3. Blood Hypercoagulability
- Endothelial cells are special type of cells that cover the inside surface of blood vessels and heart.
CONTRIBUTION OF ENDOTHELIAL CELLS TO COAGULATION
Intact endothelial cells maintain liquid blood flow by:
1- inhibiting platelet adherence
2- preventing coagulation factor activation
3- lysing blood clots that may form.
Endothelial cells can be stimulated by direct injury or by various cytokines that are produced during inflammation.
Endothelial injury results in:
1- expression of procoagulant proteins (tissue factor and vWF)→ local thrombus formation.
2- exposure of underlying vWF and basement membrane collagen → platelet aggregation and thrombus formation.
RESPONSE OF VASCULAR WALL CELLS TO INJURY( PATHOLOGIC EFFECT OF VASCULAR HEALING)
Injury to the vessel wall results in a healing response, involving:
- Intimal expansion (proliferating SMCs and newly synthesized ECM). This involves signals from ECs, platelets, and macrophages; and mediators derived from coagulation and complement cascades.
- luminal stenosis & blockage of vascular flow
Causes of Endothelial injury
1. Valvulitis
2. MI
3. Atherosclerosis
4. Traumatic or inflammatory conditions
5. Increased Blood Pressure
6. Endotoxins
7. Hypercholesterolemia
8. Radiation
9. Smoking
Stasis
- Stasis is a major factor in venous thrombi
- Normal blood flow is laminar (platelets flow centrally in the vessel lumen, separated from the endothelium by a slower moving clear zone of
plasma)
- Stasis and turbulence cause the followings:
Disuption of normal blood flow
prevent dilution of activated clotting factor
retard inflow of clotting factor inhibitor
promote endothelial cell injury
Causes of Stasis
1. Atherosclerosis
2. Aneurysms
3. Myocardial Infarction ( Non-cotractile fibers)
4. Mitral valve stenosis (atrial dilation)
5. Hyper viscosity syndromes (PCV and Sickle Cell anemia)
Hypercoagulability
A. Genetic (primary):
- mutations in the factor V gene and the prothrombin gene are the most common
B. Acquired (secondary):
- multifactorial and more complicated
- causes include: Immobilization, MI, AF, surgery, fracture, burns, Cancer, Prosthetic cardiac valves
MORPHOLOGY OF THROMBI
Can develop anywhere in the CVS (e.g., in cardiac chambers, valves, arteries, veins, or capillaries).
Arterial or cardiac thrombi→ begin at sites of endothelial injury; and are usually superimposed on an atherosclerotic plaque.
Venous thrombi → occur at sites of stasis. Most commonly the veins of the lower extremities (90%)
Thrombi are focally attached to the underlying vascular surface; arterial and venous thrombi both tend to propagate toward the heart.
→ The propagating portion of a thrombus is poorly attached → fragmentation and embolus formation
LINES OF ZAHN
Thrombi can have grossly (and microscopically) apparent laminations called lines of Zahn; these represent pale platelet and fibrin layers alternating with darker erythrocyte-rich layers.
Such lines are significant in that they represent thrombosis of flowing blood.
Mural thrombi = Thrombi occurring in heart chambers or in the aortic lumen.
Causes: -Abnormal myocardial contraction (e.g. arrhythmias, dilated cardiomyopathy, or MI) -endomyocardial injury (e.g. myocarditis, catheter trauma)
Vegetations ->Thrombi on heart valves
1- Bacterial or fungal blood-borne infections - (infective endocarditis,).
2- Non-bacterial thrombotic endocarditis occur on sterile valves.
Fate of thrombi
1. Propagation → Thrombi accumulate additional platelets and fibrin, eventually causing vessel obstruction
2. Embolization → Thrombi dislodge or fragment and are transported elsewhere in the vasculature
3. Dissolution → Thrombi are removed by fibrinolytic activity (Usually in recent thrombi)
4. Organization and recanalization → Thrombi induce inflammation and fibrosis. - recanalization (re-establishing some degree of flow) - Organization = ingrowth of endothelial cells, smooth cells and fibroblasts into the fibrin rich thrombus.
5. Superimposed infection (Mycotic aneurysm)
Venous thrombi → most common in veins of the legs
a. Superficial: e.g. Saphenous veins. - can cause local congestion, swelling, pain, and tenderness along the course of the involved vein, but they rarely embolize
a. Deep: e.g. Popliteal, Femoral and iliac vein. - more serious because they may embolize - can occur with stasis or hypercoagulable states
Causes of disease
General Pathology
Causes of disease
The causes of disease Diseases can be caused by either environmental factors, genetic factors or a combination of the two.
A. Environmental factors
Environmental causes of disease are many and are classified into:
1. Physical agents
2. Chemicals
3. Nutritional deficiencies & excesses
4. Infections & infestations
5. Immunological factors
6. Psychogenic factors
1. Physical agents
These include trauma, radiation, extremes of temperature, and electric power. These agents
apply excess physical energy, in any form, to the body.
2. Chemicals
With the use of an ever-increasing number of chemical agents such as drugs,
3. Nutritional deficiencies and excesses
Nutritional deficiencies may arise as a result of poor supply, interference with absorption, inefficient transport within the body, or defective utilization. It may take the form of deficiency.
4. Infections and infestations
Viruses, bacteria, fungi, protozoa, and metazoa all cause diseases. They may do so by causing cell destruction directly as in virus infections (for example poliomyelitis) or protozoal infections (for example malaria).
5. Immunological factors
A. Hypersensitivity reaction
This is exaggerated immune response to an antigen. For example, bronchial asthma can occur due to exaggerated immune response to the harmless pollen.
B. Immunodeficiency
This is due to deficiency of a component of the immune system which leads to increased susceptibility to different diseases. An example is AIDS.
C. Autoimmunity
This is an abnormal (exaggerated) immune reaction against the self antigens of the host. Therefore, autoimmunity is a hypersensitivity reaction against the self antigens. 4
6. Psychogenic factors
The mental stresses imposed by conditions of life, particularly in technologically advanced
communities, are probably contributory factors in some groups of diseases.
B. Genetic Factors
These are hereditary factors that are inherited genetically from parents.
Sampling methods in Public Health Dentistry
Public Health DentistrySampling methods are crucial in public health dentistry as they enable
researchers and practitioners to draw conclusions about the oral health of a
population based on a smaller, more manageable subset of individuals. This
approach is cost-effective, time-saving, and statistically valid. Here are the
most commonly used sampling methods in public health dentistry with their
applications:
1. Simple Random Sampling: This is the most basic form of
probability sampling, where each individual in the population has an equal
chance of being selected. It involves the random selection of subjects from a
complete list of all individuals (sampling frame). This method is applied when
the population is homogeneous and the sample is expected to be representative of
the entire population.
It is useful in studies that aim to determine prevalence of dental caries or
periodontal disease in a community, assess the effectiveness of oral health
programs, or evaluate the need for dental services.
2. Stratified Random Sampling: This technique involves dividing
the population into strata (subgroups) based on relevant characteristics such as
age, gender, socioeconomic status, or geographic location. Random samples are
then drawn from each stratum. This method ensures that the sample is more
representative of the population by reducing sampling error.
It is often used when the population is heterogeneous, and there is a
need to analyze the data separately for each subgroup to understand the impact
of different variables on oral health.
Applications:
Oral Health Disparities: Stratified sampling can be
used to ensure representation from different socioeconomic groups when
studying access to dental care.
Age-Specific Studies: In research focusing on pediatric
dental health, stratified sampling can help ensure that children from
various age groups are adequately represented.
3. Cluster Sampling: In this method, the population is divided
into clusters (e.g., schools, neighborhoods, or dental clinics) and a random
sample of clusters is selected. All individuals within the chosen clusters are
included in the study. This approach is useful when the population is widely
dispersed, and it reduces travel and data collection costs. It is often applied
in community-based dental health surveys and epidemiological studies.
Applications:
School-Based Dental Programs: Cluster sampling can be
used to select schools within a district to assess the oral health status of
children, where entire schools are chosen rather than individual students.
Community Health Initiatives: In evaluating the
effectiveness of community dental health programs, clusters (e.g.,
neighborhoods) can be selected to represent the population.
4. Systematic Sampling: This technique involves selecting every
nth individual from the sampling frame, where n is the sampling interval. It is
a probability sampling method that can be used when the population has some
order or pattern. For instance, in a school-based dental health survey, students
from every third grade might be chosen to participate.
This method is efficient for large populations and can be representative if
the sampling interval is appropriate.
Applications:
Community Health Assessments: Systematic sampling can
be used to select households for surveys on oral hygiene practices, where
every 10th household is chosen from a list of all households in a
neighborhood.
Patient Records Review: In retrospective studies,
systematic sampling can be applied to select patient records at regular
intervals to assess treatment outcomes.
5. Multi-stage Sampling: This is a combination of different
sampling methods where the population is divided into smaller and smaller
clusters in each stage. It is particularly useful for large-scale studies where
the population is not easily accessible or when the study requires detailed data
from various levels (e.g., national to local levels).
For example, in a multi-stage design, a random sample of states might
be selected in the first stage, followed by random samples of counties within
those states, and then schools within the selected counties.
Applications in Public Dental Health:
National Oral Health Surveys: Researchers may first
randomly select states or regions (clusters) and then randomly select dental
clinics or households within those regions to assess the prevalence of
dental diseases or access to dental care.
Community Health Assessments: In a large city,
researchers might select neighborhoods as the first stage and then sample
residents within those neighborhoods to evaluate oral health behaviors and
access to dental services.
Program Evaluation: Multi-stage sampling can be used to
evaluate the effectiveness of community dental health programs by selecting
specific program sites and then sampling participants from those sites.
6. Convenience Sampling: Although not a probability sampling method,
convenience sampling is often used in public health dentistry due to practical
constraints. It involves selecting individuals who are readily available and
willing to participate. While this method may introduce bias, it is useful for
pilot studies, exploratory research, or when the goal is to obtain preliminary
data quickly and inexpensively. It is important to be cautious when generalizing
findings from convenience samples to the broader population.
Applications:
Pilot Studies: Convenience sampling can be used in
preliminary studies to gather initial data on dental health behaviors among
easily accessible groups, such as dental clinic patients.
Focus Groups: In qualitative research, convenience
sampling may be used to gather opinions from dental patients who are readily
available for discussion.
7. Quota Sampling: This is a non-probability sampling method
where the researcher sets quotas for specific characteristics of the population
(e.g., age, gender) and then recruits individuals to meet those quotas. It is
often used in surveys where it is crucial to have a representative sample
regarding certain demographic variables.
However, it may not be as statistically robust as probability sampling
methods and can introduce bias if the quotas are not met correctly.
Applications in Public Dental Health:
Targeted Surveys: Researchers can use quota sampling to
ensure that specific demographic groups (e.g., children, elderly, low-income
individuals) are adequately represented in surveys assessing oral health
knowledge and behaviors.
Program Evaluation: In evaluating community dental
health programs, quota sampling can help ensure that participants reflect
the diversity of the target population, allowing for a more comprehensive
understanding of program impact.
Focus Groups: Quota sampling can be used to assemble
focus groups for qualitative research, ensuring that participants represent
various perspectives based on predetermined characteristics relevant to the
study.
8. Purposive (Judgmental) ampling: In this approach,
participants are selected based on specific criteria that the researcher
believes are important for the study. This method is useful for studies that
require in-depth understanding, such as qualitative research or when studying a
rare condition. It is essential to ensure that the sample is diverse enough to
provide a comprehensive perspective.
Applications:
Expert Interviews: In studies exploring dental policy
or public health initiatives, purposive sampling can be used to select key
informants, such as dental professionals or public health officials.
Targeted Health Interventions: When studying specific
populations (e.g., individuals with disabilities), purposive sampling
ensures that the sample includes individuals who meet the criteria.
9. Snowball Sampling: This is a non-probability method where
initial participants are selected based on the researcher's judgment and then
asked to refer others with similar characteristics. It is often used in studies
involving hard-to-reach populations, such as those with rare oral conditions or
specific behaviors.
While it can provide valuable insights, the sample may not be representative
of the broader population.
Applications :
Studying Marginalized Groups: Researchers can use
snowball sampling to identify and recruit individuals from marginalized
communities (e.g., homeless individuals, low-income families) to assess
their oral health needs and barriers to accessing dental care.
Behavioral Research: In studies examining specific
behaviors (e.g., smoking and oral health), initial participants can help
identify others who share similar characteristics or experiences,
facilitating data collection from a relevant population.
Qualitative Research: Snowball sampling can be
effective in qualitative studies exploring the experiences of individuals
with specific dental conditions or those participating in community dental
health programs.
10. Time-Space Sampling: This technique is used to study
populations that are not fixed in place, such as patients attending a dental
clinic during specific hours. Researchers select random times and days and then
include all patients who visit the clinic during those times in the sample.
This method can be useful for assessing the representativeness of
clinic-based studies.
Applications
Mobile Populations: Researchers can use time-space
sampling to assess the oral health of populations that may not have a fixed
residence, such as migrant workers or individuals living in temporary
housing.
Event-Based Sampling: Public health campaigns or dental
health fairs can be used as time-space sampling points to recruit
participants for surveys on oral health behaviors and access to care.
Community Outreach: Time-space sampling can help
identify individuals attending community events or clinics to gather data on
their oral health status and service utilization.
The choice of sampling method in public health dentistry depends on the research
question, the population's characteristics, the available resources, and the
desired level of generalizability. Probability sampling methods are generally
preferred for their scientific rigor, but non-probability methods may be
necessary under certain circumstances. It is essential to justify the chosen
method and consider its limitations when interpreting the results.
Manipulation of Acrylic Resins
Dental Materials
Manipulation
Mixture of powder and liquid is painted onto working cast to create shape for acrylic appliance à After curing of mixture, the shape and fit are adjusted by grinding with burrs and stones with a slow-speed handpiece .Acrylic dust is irritating to epithelial tissues of nasopharynx and skin and may produce allergic dermatitis or other reactions. Grinding may heat polymer to temperatures that depolymerize and release monomer vapor. which may be an irritant
Nail Biting Habits
OrthodonticsNail Biting Habits
Nail biting, also known as onychophagia, is one of the most
common habits observed in children and can persist into adulthood. It is often
associated with internal tension, anxiety, or stress. Understanding the
etiology, clinical features, and management strategies for nail biting is
essential for addressing this habit effectively.
Etiology
Emotional Problems:
Persistent nail biting may indicate underlying emotional issues,
such as anxiety, stress, or tension. It can serve as a coping mechanism
for dealing with these feelings.
Psychosomatic Factors:
Nail biting can be a psychosomatic response to stress or emotional
discomfort, manifesting physically as a way to relieve tension.
Successor of Thumb Sucking:
For some children, nail biting may develop as a successor to thumb
sucking, particularly as they transition from one habit to another.
Clinical Features
Dental Effects:
Crowding: Nail biting can contribute to dental
crowding, particularly if the habit leads to changes in the position of
the teeth.
Rotation: Teeth may become rotated or misaligned
due to the pressure exerted during nail biting.
Alteration of Incisal Edges: The incisal edges of
the anterior teeth may become worn down or altered due to repeated
contact with the nails.
Soft Tissue Changes:
Inflammation of Nail Bed: Chronic nail biting can
lead to inflammation and infection of the nail bed, resulting in
redness, swelling, and discomfort.
Management
Awareness:
The first step in management is to make the patient aware of their
nail biting habit. Understanding the habit's impact on their health and
appearance can motivate change.
Addressing Emotional Factors:
It is important to identify and treat any underlying emotional
issues contributing to the habit. This may involve counseling or therapy
to help the individual cope with stress and anxiety.
Encouraging Outdoor Activities:
Engaging in outdoor activities and physical exercise can help reduce
tension and provide a positive outlet for stress, potentially decreasing
the urge to bite nails.
Behavioral Modifications:
Nail Polish: Applying a bitter-tasting nail polish
can deter nail biting by making the nails unpalatable.
Light Cotton Mittens: Wearing mittens or gloves can
serve as a physical reminder to avoid nail biting and can help break the
habit.
Positive Reinforcement:
Encouraging and rewarding the individual for not biting their nails
can help reinforce positive behavior and motivate them to stop.
The Palate
AnatomyThe Palate
The palate forms the arched roof of the mouth and the floor of the nasal cavities.
The palate consists of two regions: the anterior 2/3 or bony part, called the hard palate, and the mobile posterior 1/3 or fibromuscular part, known as the soft palate.
The Hard Palate
The anterior bony part of the palate is formed by the palatine process of the maxillae and the horizontal plates of the palatine bones.
Anteriorly and laterally, the hard palate is bounded by the alveolar processes and the gingivae.
Posteriorly, the hard palate is continuous with the soft palate.
The incisive foramen is the mouth of the incisive canal.
This foramen is located posterior to the maxillary central incisor teeth.
This foramen is the common opening for the right and left incisive canals.
The incisive canal and foramen transmit the nasopalatine nerve and the terminal branches of the sphenopalatine artery.
Medial to the third molar tooth, the greater palatine foramen pierces the lateral border of the bony palate.
The greater palatine vessels and nerve emerge from this foramen and run anteriorly into two grooves on the palate.
The lesser palatine foramen transmits the lesser palatine nerve and vessels.
This runs to the soft palate and adjacent structures.
Use of local anesthetics during pregnancy
Pharmacology
Use of local anesthetics during pregnancy
Local anesthetics (injectable)
Drug FDA category
Articaine C
Bupivacaine C
Lidocaine B
Mepivacaine C
Prilocaine B
Vasoconstrictors
Epinephrine 1:200,000 or 1:100,000 C (higher doses)
Levonordefrin 1:20,000 Not ranked
Local anesthetics (topical)
Benzocaine C
Lidocaine B
Dental Terminology
Dental Anatomy
Dental Terminology.
Cusp: a point or peak on the occlusal surface of molar and premolar teeth and on the incisal edges of canines.
Contact: a point or area where one tooth is in contact (touching) another tooth
Cingulum: a bulge or elevation on the lingual surface of incisors or canines. It makes up the bulk of the cervical third of the lingual surface. Its convexity mesiodistally resembles a girdle encircling the lingual surface at the cervical.
Fissure: A linear fault that sometimes occurs in a developmental groove by incomplete or imperfect joining of the lobes. A pit is usually found at the end of a developmental groove or a place where two fissures intersect.
Lobe: one of the primary centers of formation in the development of the crown of the tooth.
Mamelon: A lobe seen on anterior teeth; any one of three rounded protuberances seen on the unworn surfaces of freshly erupted anterior teeth.
Ridge: Any linear elevation on the surface of a tooth. It is named according to its location or form. Examples are buccal ridges, incisal ridges, marginal ridges, and so on.
Marginal ridges are those rounded borders of enamel which form the margins of the surfaces of premolars and molars, mesially and distally, and the mesial and distal margins of the incisors and canines lingually.
Triangular ridges are those ridges which descend from the tips of the cusps of molars and premolars toward the central part of the occlusal surface. Transverse ridges are created when a buccal and lingual triangular ridge join.
Oblique ridges are seen on maxillary molars and are a companion to the distal oblique groove.
Cervical ridges are the height of contour at the gingival, on certain deciduous and permanent teeth.
Fossa: An irregular, rounded depression or concavity found on the surface of a tooth. A lingual fossa is found on the lingual surface of incisors. A central fossa is found on the occlusal surface of a molar. They are formed by the converging of ridges terminating at a central point in the bottom of a depression where there is a junction of grooves
Pit: A small pinpoint depression located at the junction of developmental grooves or at the terminals of these groops. A central pit is found in the central fossa on the occlusal surfaces of molars where developmental grooves join. A pit is often the site of the onset of Dental caries
Developmental groove: A sharply defined, narrow and linear depression formed during tooth development and usually separating lobes or major portions of a tooth.
A supplemental groove is also a shallow linear depression but it is usually less distinct and is more variable than a developmental groove and does not mark the junction of primary parts of a tooth.
Buccal and lingual grooves are developmental grooves found on the buccal and lingual surfaces of posterior teeth.
Tubercle: A small elevation produced by an extra formation of enamel. These occur on the marginal ridges of posterior teeth or on the cingulum of anterior teeth. These are deviations from the typical form.
Interproximal space: The triangular space between the adjacent teeth cervical to the contact point. The base of the triangle is the alveolar bone; the sides are the proximal surfaces of the adjacent teeth.
Sulcus:-An elongated valley or depression in the surface of a tooth formed by the inclines of adjacent cusp or ridges.
Embrasures: When two teeth in the same arch are in contact, their curvatures adjacent to the contact areas form spillway spaces called embrasures. There are three embrasures:
(1) Facial (buccal or labial)
(2) Occlusal or incisal
(3) Lingual
(NOTE: there are three embrasures; the fourth potential space is the interproximal space ).