NEET MDS Synopsis
Recurrent Aphthous Ulcers
Pedodontics
Recurrent Aphthous Ulcers (Canker Sores)
Overview of Recurrent Aphthous Ulcers (RAU)
Definition:
Recurrent aphthous ulcers, commonly known as canker sores, are painful
ulcerations that occur on the unattached mucous membranes of the mouth.
They are characterized by their recurrent nature and can significantly
impact the quality of life for affected individuals.
Demographics:
RAU is most prevalent in school-aged children and young adults, with a
peak incidence between the ages of 10 and 19 years.
It is reported to be the most common mucosal disorder across various
ages and races globally.
Clinical Features
Characteristics:
RAU is defined by recurrent ulcerations on the moist mucous membranes of
the mouth.
Lesions can be discrete or confluent, forming rapidly in certain areas.
They typically feature:
A round to oval crateriform base.
Raised, reddened margins.
Significant pain.
Types of Lesions:
Minor Aphthous Ulcers:
Usually single, smaller lesions that heal without scarring.
Major Aphthous Ulcers (RAS):
Larger, more painful lesions that may take longer to heal and can
leave scars.
Also referred to as periadenitis mucosa necrotica recurrens or
Sutton disease.
Herpetiform Ulcers:
Multiple small lesions that can appear in clusters.
Duration and Healing:
Lesions typically persist for 4 to 12 days and heal uneventfully, with
scarring occurring only rarely and usually in cases of unusually large
lesions.
Epidemiology
Prevalence:
The condition occurs approximately three times more frequently in white
children compared to black children.
Prevalence estimates of RAU range from 2% to 50%, with most estimates
falling between 5% and 25%. Among medical and dental students, the
estimated prevalence is between 50% and 60%.
Associated Conditions
Systemic Associations:
RAS has been linked to several systemic diseases, including:
PFAPA Syndrome: Periodic fever, aphthous stomatitis,
pharyngitis, and adenitis.
Behçet Disease: A systemic condition characterized by
recurrent oral and genital ulcers.
Crohn's Disease: An inflammatory bowel disease that can
present with oral manifestations.
Ulcerative Colitis: Another form of inflammatory bowel
disease.
Celiac Disease: An autoimmune disorder triggered by gluten.
Neutropenia: A condition characterized by low levels of
neutrophils, leading to increased susceptibility to infections.
Immunodeficiency Syndromes: Conditions that impair the
immune system.
Reiter Syndrome: A type of reactive arthritis that can
present with oral ulcers.
Systemic Lupus Erythematosus: An autoimmune disease that
can cause various oral lesions.
MAGIC Syndrome: Mouth and genital ulcers with inflamed
cartilage.
Clinical Signs and Their Significance
Oral and Maxillofacial SurgeryClinical Signs and Their Significance
Understanding various clinical signs is crucial for diagnosing specific
conditions and injuries. Below are descriptions of several important signs,
including Battle sign, Chvostek’s sign, Guerin’s sign, and Tinel’s sign, along
with their clinical implications.
1. Battle Sign
Description: Battle sign refers to ecchymosis
(bruising) in the mastoid region, typically behind the ear.
Clinical Significance: This sign is indicative of a
posterior basilar skull fracture. The bruising occurs due to the
extravasation of blood from the fracture site, which can be a sign of
significant head trauma. It is important to evaluate for other associated
injuries, such as intracranial hemorrhage.
2. Chvostek’s Sign
Description: Chvostek’s sign is characterized by the
twitching of the facial muscles in response to tapping over the area of the
facial nerve (typically in front of the ear).
Clinical Significance: This sign is often observed in
patients who are hypocalcemic (have low calcium levels). The twitching
indicates increased neuromuscular excitability due to low calcium levels,
which can lead to tetany and other complications. It is commonly assessed in
conditions such as hypoparathyroidism.
3. Guerin’s Sign
Description: Guerin’s sign is the presence of
ecchymosis along the posterior soft palate bilaterally.
Clinical Significance: This sign is indicative of
pterygoid plate disjunction or fracture. It suggests significant trauma to
the maxillofacial region, often associated with fractures of the skull base
or facial skeleton. The presence of bruising in this area can help in
diagnosing the extent of facial injuries.
4. Tinel’s Sign
Description: Tinel’s sign is a provocative test where
light percussion over a nerve elicits a distal tingling sensation.
Clinical Significance: This sign is often interpreted
as a sign of small fiber recovery in regenerating nerve sprouts. It is
commonly used in the assessment of nerve injuries, such as carpal tunnel
syndrome or after nerve repair surgeries. A positive Tinel’s sign indicates
that the nerve is healing and that sensory function may be returning.
Membrane Potential
PhysiologyMembrane Potential
Membrane potentials will occur across cell membranes if
1) there is a concentration gradient of an ion
2) there is an open channel in the membrane so the ion can move from one side to the other
The Sodium Pump Sets Up Gradients of Na and K Across Cell Membranes
All cells have the Na pump in their membranes
Pumps 3 Nas out and 2 Ks in for each cycle
Requires energy from ATP
Uses about 30% of body's metabolic energy
This is a form of active transport- can pump ions "uphill", from a low to a high concentration
This produces concentration gradients of Na & K across the membrane
Typical concentration gradients:
In mM/L
Out mM/L
Gradient orientation
Na
10
150
High outside
K
140
5
High inside
The ion gradients represent stored electrical energy (batteries) that can be tapped to do useful work
The Na pump is of ancient origin, probably originally designed to protect cell from osmotic swelling
Inhibited by the arrow poisons ouabain and digitalis
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.
Mechanical properties
Dental Materials
Mechanical properties
1. Resolution of forces
Uniaxial (one-dimensional) forces-compression, tension, and shear
Complex forces-torsion, flexion. And diametral
2. Normalization of forces and deformatations
Stress
Applied force (or material’s resistance to force) per unit area
Stress-force/area (MN/m2)
Strain
Change in length per unit of length because of force
Strain-(L- Lo)/(Lo); dimensionless units
3. Stress-strain diagrams
Plot of stress (vertical) versus strain (horizontal)
Allows convenient comparison of materials
Different curves for compression, tension, and shear
Curves depend on rate of testing and temperature
4. Analysis of curves
Elastic behavior
Initial response to stress is elastic strain
Elastic modulus-slope of first part of curve and represents stiffness of material or the resistance to deformation under force
Elastic limit (proportional limit)- stress above which the material no longer behaves totally elastically
Yield strength-stress that is an estimate of the elastic limit at 0.002 permanent strain
Hardness-value on a relative scale that estimates the elastic limit in terms of a material’s resistance to indentation (Knoop hardness scale, Diamond pyramid, Brinnell, Rockwell hardness scale, Shore A hardness scale, Mohs hardness scale
Resilience-area under the stress strain curve up to the elastic limit (and it estimates the total elastic energy that can be absorbed before the onset of plastic deformation)
Elastic and plastic behavior
Beyond the stress level of the elastic limit, there is a combination of elastic and plastic strain
Ultimate strength-highest stress reached before fracture; the ultimate compressive strength is greater than the ultimate shear strength and the ultimate tensile strength
Elongation (percent elongation)- percent change in length up to the point of fracture = strain x 100%
Brittle materials-<5% elongation at fracture
Ductile materials->5% elongation at fracture
Toughness-area under the stress strain curve up to the point of fracture (it estimates the total energy absorbed up to fracture)
Time-dependent behavior
the faster a stress is applied, the more likely a material is to store the energy elastically and not plastically
Creep-strain relaxation
Stress relaxation
Biologic Width
Conservative DentistryBiologic Width and Drilling Speeds
In restorative dentistry, understanding the concepts of biologic width and
the appropriate drilling speeds is essential for ensuring successful outcomes
and maintaining periodontal health.
1. Biologic Width
Definition
Biologic Width: The biologic width is the area of soft
tissue that exists between the crest of the alveolar bone and the gingival
margin. It is crucial for maintaining periodontal health and stability.
Dimensions: The biologic width is ideally approximately
3 mm wide and consists of:
1 mm of Connective Tissue: This layer provides
structural support and attachment to the tooth.
1 mm of Epithelial Attachment: This layer forms a
seal around the tooth, preventing the ingress of bacteria and other
irritants.
1 mm of Gingival Sulcus: This is the space between
the tooth and the gingiva, which is typically filled with gingival
crevicular fluid.
Importance
Periodontal Health: The integrity of the biologic width
is essential for the health of the periodontal attachment apparatus. If this
zone is compromised, it can lead to periodontal inflammation and other
complications.
Consequences of Violation
Increased Risk of Inflammation: If a restorative
procedure violates the biologic width (e.g., by placing a restoration too
close to the bone), there is a higher likelihood of periodontal
inflammation.
Apical Migration of Attachment: Violation of the
biologic width can cause the attachment apparatus to move apically, leading
to loss of attachment and potential periodontal disease.
2. Recommended Drilling Speeds
Drilling Speeds
Ultra Low Speed: The recommended speed for drilling
channels is between 300-500 rpm.
Low Speed: A speed of 1000 rpm is also considered low
speed for certain procedures.
Heat Generation
Minimal Heat Production: At these low speeds, very
little heat is generated during the drilling process. This is crucial for:
Preventing Thermal Damage: Low heat generation
reduces the risk of thermal damage to the tooth structure and
surrounding tissues.
Avoiding Pulpal Irritation: Excessive heat can lead
to pulpal irritation or necrosis, which can compromise the health of the
tooth.
Cooling Requirements
No Cooling Required: Because of the minimal heat
generated at these speeds, additional cooling with water or air is typically
not required. This simplifies the procedure and reduces the complexity of
the setup.
Eosinopenia
General Pathology
Eosinopenia:
Causes
-Corticoid effect (Cushing's syndrome or therapy).
-Stress.
Applegate's Classification for edentulous arches
ProsthodonticsApplegate's Classification is a system used to categorize edentulous
(toothless) arches in preparation for denture construction. The classification
is based on the amount and quality of the remaining alveolar ridge, the
relationship of the ridge to the residual ridges, and the presence of undercuts.
The system is primarily used in the context of complete denture prosthodontics
to determine the best approach for achieving retention, stability, and support
for the dentures.
Applegate's Classification for edentulous arches:
1. Class I: The alveolar ridge has a favorable arch form and sufficient height
and width to provide adequate support for a complete denture without the need
for extensive modifications. This is the ideal scenario for denture
construction.
2. Class II: The alveolar ridge has a favorable arch form but lacks the
necessary height or width to provide adequate support. This may require the use
of denture modifications such as flanges to enhance retention and support.
3. Class III: The ridge lacks both height and width, and there may be undercuts
or excessive resorption. In this case, additional procedures such as ridge
augmentation or the use of implants might be necessary to improve the foundation
for the denture.
4. Class IV: The ridge has an unfavorable arch form, often with significant
resorption, and may require extensive surgical procedures or adjuncts like
implants to achieve a functional and stable denture.
5. Class V: This is the most severe classification where the patient has no
residual alveolar ridge, possibly due to severe resorption, trauma, or surgical
removal. In such cases, the creation of a functional and stable denture may be
highly challenging and might necessitate advanced surgical procedures and/or the
use of alternative prosthetic options like over-dentures with implant support.
It's important to note that this classification is a guide, and individual
patient cases may present with a combination of features from different classes
or may require customized treatment plans based on unique anatomical and
functional requirements.