NEET MDS Synopsis
Bases
Conservative DentistryBases in Restorative DentistryBases are an essential component in restorative dentistry, serving as a
thicker layer of material placed beneath restorations to provide additional
protection and support to the dental pulp and surrounding structures. Below is
an overview of the characteristics, objectives, and types of bases used in
dental practice.
1. Characteristics of BasesA. Thickness
Typical Thickness: Bases are generally thicker than
liners, typically ranging from 1 to 2 mm. Some bases may be
around 0.5 to 0.75 mm thick.
B. Functions
Thermal Protection: Bases provide thermal insulation to
protect the pulp from temperature changes that can occur during and after
the placement of restorations.
Mechanical Support: They offer supplemental mechanical
support for the restoration by distributing stress on the underlying dentin
surface. This is particularly important during procedures such as amalgam
condensation, where forces can be applied to the restoration.
2. Objectives of Using BasesThe choice of base material and its application depend on the Remaining
Dentin Thickness (RDT), which is a critical factor in determining the
need for a base:
RDT > 2 mm: No base is required, as there is sufficient
dentin to protect the pulp.
RDT 0.5 - 2 mm: A base is indicated, and the choice of
material depends on the restorative material being used.
RDT < 0.5 mm: Calcium hydroxide (Ca(OH)₂) or Mineral
Trioxide Aggregate (MTA) should be used to promote the formation of
reparative dentin, as the remaining dentin is insufficient to provide
adequate protection.
3. Types of BasesA. Common Base Materials
Zinc Phosphate (ZnPO₄): Known for its good mechanical
properties and thermal insulation.
Glass Ionomer Cement (GIC): Provides thermal protection
and releases fluoride, which can help in preventing caries.
Zinc Polycarboxylate: Offers good adhesion to tooth
structure and provides thermal insulation.
B. Properties
Mechanical Protection: Bases distribute stress
effectively, reducing the risk of fracture in the restoration and protecting
the underlying dentin.
Thermal Insulation: Bases are poor conductors of heat
and cold, helping to maintain a stable temperature at the pulp level.
Ankylosing spondylitis
Orthopaedics
- Ankylosing spondylitis or AS, is a form of arthritis that primarily affects the spine, although other joints can become involved.
- It causes inflammation of the spinal joints (vertebrae) that can lead to severe, chronic pain and discomfort.
- Most people with AS have an antigen called HLA-B27
- Ankylosing spondylitis (AS) is a chronic, multisystem inflammatory disorder involving primarily the sacroiliac joints and the axial skeleton.
Key components of the patient history that suggest AS include the following:
• Insidious onset of low back pain - The most common symptom
• Onset of symptoms before age 40 years
• Presence of symptoms for more than 3 months
• Symptoms worse in the morning or with inactivity
• Improvement of symptoms with exercise
Complications
- AS can cause pain and inflammation in other parts of your body.
- Eyes. About 40% of people with AS have an eye problem called uveitis. It’s a painful inflammation that can blur your vision and make you sensitive to bright light.
- Heart valve. It’s not common, but AS can enlarge the aorta, the largest artery in your body. This can change the shape of the aortic valve, which can allow blood to leak back into your heart.
- Cancer. A large study found that people with AS are more likely to get certain types of cancers. They include bone and prostate cancers in men and colon cancer in women, as well as blood-related cancers in both sexes.
Agents Used for Sedation in Children
PedodonticsAgents Used for Sedation in Children
Nitrous Oxide (N₂O)
Type: Gaseous agent
Description: Commonly used for conscious sedation
in pediatric dentistry. It provides anxiolytic and analgesic effects,
making dental procedures more tolerable for children.
Benzodiazepines
Examples:
Diazepam: Used for its anxiolytic and sedative
properties.
Midazolam: Frequently utilized for its rapid
onset and short duration of action.
Barbiturates
Description: Sedative-hypnotics that can be used
for sedation, though less commonly in modern practice due to the
availability of safer alternatives.
Chloral Hydrate
Description: A sedative-hypnotic agent used for its
calming effects in children.
Narcotics
Examples:
Meperidine: Provides analgesia and sedation.
Fentanyl: A potent opioid used for sedation and
pain management.
Antihistamines
Examples:
Hydroxyzine: An anxiolytic and sedative.
Promethazine (Phenergan): Used for sedation and
antiemetic effects.
Chlorpromazine: An antipsychotic that can also
provide sedation.
Diphenhydramine: An antihistamine with sedative
properties.
Dissociative Agents
Example:
Ketamine: Provides dissociative anesthesia,
analgesia, and sedation. It is particularly useful in emergency
settings and for procedures that may cause significant discomfort.
Time for tooth development
Dental Anatomy
Time for tooth development
Entire primary dentition initiated between 6 and 8 weeks of embryonic development.
Successional permanent teeth initiated between 20th week in utero and 10th month after birth Permanent molars between 20th week in utero (first molar) and 5th year of life (third molar)
Necrotizing Sialometaplasia
Oral and Maxillofacial SurgeryNecrotizing Sialometaplasia
Necrotizing sialometaplasia is an inflammatory lesion that
primarily affects the salivary glands, particularly the minor salivary glands.
It is characterized by necrosis of the glandular tissue and subsequent
metaplastic changes. The exact etiology of this condition remains unknown, but
several factors have been suggested to contribute to its development.
Key Features
Etiology:
The precise cause of necrotizing sialometaplasia is not fully
understood. However, common suggested causes include:
Trauma: Physical injury to the salivary glands
leading to ischemia (reduced blood flow).
Acinar Necrosis: Death of the acinar cells (the
cells responsible for saliva production) in the salivary glands.
Squamous Metaplasia: Transformation of
glandular epithelium into squamous epithelium, which can occur in
response to injury or inflammation.
Demographics:
The condition is more commonly observed in men, particularly in
their 5th to 6th decades of life (ages 50-70).
Common Sites:
Necrotizing sialometaplasia typically affects the minor
salivary glands, with common locations including:
The palate
The retromolar area
The lip
Clinical Presentation:
The lesion usually presents as a large ulcer or an ulcerated
nodule that is well-demarcated from the surrounding normal
tissue.
The edges of the lesion often show signs of an inflammatory
reaction, which may include erythema and swelling.
Management:
Conservative Treatment: The management of
necrotizing sialometaplasia is generally conservative, as the lesion is
self-limiting and typically heals on its own.
Debridement: Gentle debridement of the necrotic
tissue may be performed using hydrogen peroxide or saline to promote
healing.
Healing Time: The lesion usually heals within 6
to 8 weeks without the need for surgical intervention.
Miscellaneous Non-Neoplastic Diseases - Erythema multiforme
General Pathology
Erythema multiforme is a hypersensitivity reaction to an infection (Mycoplasma), drugs or various autoimmune diseases.
- probable immunologic disease
- lesions vary from erythematous macules, papules, or vesicles.
- papular lesions frequently look like a target with a pale central area.
- extensive erythema multiforme in children is called Stevens-Johnson syndrome, where there is extensive skin and mucous membrane involvement with fever and respiratory symptoms.
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.
Myocardial infarction (MI)—heart attack
General Pathology
Myocardial infarction (MI)—heart attack
A. Ischemia versus MI: Ischemia is a reversible mismatch between the supply and demand of oxygen. Infarction
is an irreversible mismatch that results in cell death caused by the lack of blood flow (oxygenation). For instance, chest pain caused by ischemia can be relieved by administering nitroglycerin (a vasodilator) to the patient. If the patient has an MI, the pain will not be relieved with nitroglycerin.
1. MIs most commonly occur when a coronary artery is occluded by a thrombus generated in an atherosclerotic artery.
2. Symptoms include:
a. Chest pain, shortness of breath.
b. Diaphoresis (sweating), clammy hands.
c. Nausea, vomiting.
3. Consequences:
a. Death (one third of patients).
b. Arrhythmias (most common immediate cause of death).
c. Congestive heart failure.
d. Myocardial rupture, which may result in death from cardiac tamponade.
e. Thrombus formation on infarcted tissue; may result in systemic embolism.