NEET MDS Synopsis
FUNDAMENTALS OF INJECTION TECHNIQUE
Pharmacology
FUNDAMENTALS OF INJECTION TECHNIQUE
There are 6 basic techniques for achieving local anesthesia of the structures of the oral cavity:
1. Nerve block
2. Field block
3. Infiltration/Supraperiosteal
4. Topical
5. Periodontal ligament (PDL)
6. Intraosseous
Nerve block- Nerve block anesthesia requires local anesthetic to be deposited in close proximity to a nerve trunk. This results in the blockade of nerve impulses distal to this point. It is also important to note that arteries and veins accompany these nerves and can be damaged. To be effective, the local anesthetic needs to pass only through the nerve membrane to block nerve conduction Field block/Infiltration/Supraperiosteal - Field block, infiltration and supraperiosteal injection techniques, rely on the ability of local anesthetics to diffuse through numerous structures to reach the nerve or nerves to be anesthetized:
- Periosteum
- Cortical bone
- Cancellous bone
- Nerve membrane
Topical - Topical anesthetic to be effective requires diffusion through mucous membranes and nerve membrane of the nerve endings near the tissue surface
PDL/Intraosseous - The PDL and intraosseous injection techniques require diffusion of local anesthetic solution through the cancellous bone (spongy) to reach the dental plexus of nerves innervating the tooth or teeth in the immediate area of the injection. The local anesthetic then diffuses through the nerve membrane
Thiopental
Pharmacology
Thiopental
- A barbiturate that is generally used to induce anesthesia.
- The temporal course of effects from induction to recovery depends almost entirely upon progressive redistribution.
- Metabolic degradation or excretion during anesthesia is negligible, except in the case of methohexital.
- The barbiturates produce minimal analgesia.
- Respiratory depression may be pronounced.
- Cardiac output is reduced while total peripheral resistance is increased.
- It does not sensitize the heart to catecholamines.
- It may cause bronchiospasm, especially in asthmatics.
- It is contraindicated in acute intermittent porphyria.
Weak Acids and pKa
Biochemistry
Weak Acids and pKa
• The strength of an acid can be determined by its dissociation constant, Ka.
• Acids that do not dissociate significantly in water are weak acids.
• The dissociation of an acid is expressed by the following reaction: HA = H+ + A- and the dissociation constant Ka = [H+ ][A- ] / [HA]
• When Ka < 1, [HA] > [H+ ][A- ] and HA is not significantly dissociated. Thus, HA is a weak acid when ka < 1.
• The lesser the value of Ka, the weaker the acid.
• Similar to pH, the value of Ka can also be represented as pKa.
• pKa = -log Ka.
• The larger the pKa, the weaker the acid.
• pKa is a constant for each conjugate acid and its conjugate base pair.
• Most biological compounds are weak acids or weak bases.
Types of Crying
PedodonticsTypes of Crying
Obstinate Cry:
Characteristics: This cry is loud, high-pitched,
and resembles a siren. It often accompanies temper tantrums, which may
include kicking and biting.
Emotional Response: It reflects the child's
external response to anxiety and frustration.
Physical Manifestation: Typically involves a lot of
tears and convulsive sobbing, indicating a high level of distress.
Frightened Cry:
Characteristics: This cry is not about getting what
the child wants; instead, it arises from fear that overwhelms the
child's ability to reason.
Physical Manifestation: Usually involves small
whimpers, indicating a more subdued response compared to the obstinate
cry.
Hurt Cry:
Characteristics: This cry is a reaction to physical
discomfort or pain.
Physical Manifestation: It may start with a single
tear that runs down the child's cheek without any accompanying sound or
resistance, indicating a more internalized response to pain.
Compensatory Cry
Characteristics:
This type of cry is not a traditional cry; rather, it is a sound
that the child makes in response to a specific stimulus, such as the
sound of a dental drill.
It is characterized by a constant whining noise rather than the
typical crying sounds associated with distress.
Physical Manifestation:
There are no tears or sobs associated with this cry. The child
does not exhibit the typical signs of emotional distress that
accompany other types of crying.
The sound is directly linked to the presence of the stimulus
(e.g., the drill). When the stimulus stops, the whining also ceases.
Emotional Response:
The compensatory cry may indicate a child's attempt to cope with
discomfort or fear in a situation where they feel powerless or
anxious. It serves as a way for the child to express their
discomfort without engaging in more overt forms of crying.
Theory of Object Relations
PedodonticsMargaret S. Mahler’s Theory of Object Relations
Overview of Mahler’s Theory
Margaret S. Mahler's theory of object relations focuses on the development of
personality in early childhood through the understanding of the child's
relationship with their primary caregiver. Mahler proposed that this development
occurs in three main stages, each characterized by specific psychological
processes and milestones.
Stages of Childhood Development
Normal Autistic Phase (0 – 1 Year):
Description: This phase is characterized by a state
of half-sleep and half-wakefulness. Infants are primarily focused on
their internal needs and experiences.
Key Features:
The infant is largely unaware of the external environment and
caregivers.
The primary goal during this phase is to achieve equilibrium
with the environment, establishing a sense of basic security and
comfort.
Normal Symbiotic Phase (3 – 4 Weeks to 4 – 5 Months):
Description: In this phase, the infant begins to
develop a slight awareness of the caregiver, but both the infant and
caregiver remain undifferentiated in their relationship.
Key Features:
The infant experiences a sense of oneness with the caregiver,
relying on them for emotional and physical needs.
There is a growing recognition of the caregiver's presence, but
the infant does not yet see themselves as separate from the
caregiver.
Separation-Individualization Phase (5 to 36 Months):
This phase is crucial for the development of a sense of self and
independence. It is further divided into four subphases:
a. Differentiation (5 – 10 Months):
Description: The infant begins to recognize the
distinction between themselves and the caregiver.
Key Features:
Increased awareness of the caregiver's presence and the
environment.
The infant may start to explore their surroundings while still
seeking reassurance from the caregiver.
b. Practicing Period (10 – 16 Months):
Description: During this period, the child actively
practices their emerging mobility and independence.
Key Features:
The child explores the environment more freely, often moving
away from the caregiver but returning for comfort.
This stage is marked by a sense of exhilaration as the child
gains new skills.
c. Rapprochement (16 – 24 Months):
Description: The child begins to seek a balance
between independence and the need for the caregiver.
Key Features:
The child may exhibit ambivalence, wanting to explore but also
needing the caregiver's support.
This phase is characterized by emotional fluctuations as the
child navigates their growing autonomy.
d. Consolidation and Object Constancy (24 – 36 Months):
Description: The child develops a more stable sense
of self and an understanding of the caregiver as a separate entity.
Key Features:
The child achieves object permanence, recognizing that the
caregiver exists even when not in sight.
This phase solidifies the child's ability to maintain emotional
connections with the caregiver while exploring independently.
Merits of Mahler’s Theory
Applicability to Children: Mahler's theory provides
valuable insights into the emotional and psychological development of
children, particularly in understanding the dynamics of attachment and
separation from caregivers.
Demerits of Mahler’s Theory
Lack of Comprehensiveness: While Mahler's theory offers
important perspectives on early childhood development, it is not considered
a comprehensive theory. It may not account for all aspects of personality
development or the influence of broader social and cultural factors.
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
Hepatitis Summary
General Pathology
Summary
Hepatitis A → ssRNA → Picornavirus → Oral–anal
Hepatitis B → dsDNA → Hepadnavirus → Sexual contact , Blood (needles), Perinatal
Hepatitis C → ssRNA → Flavivirus → Sexual contact , Blood (needles)
Hepatitis D → ssRNA → Deltavirus → Sexual contact, Blood (needles)
Hepatitis E → ssRNA → Calicivirus → Oral–anal
Polyprotic Acids
Biochemistry
Polyprotic Acids
• Some acids are polyprotic acids; they can lose more than one proton.
• In this case, the conjugate base is also a weak acid.
• For example: Carbonic acid (H2CO3 ) can lose two protons sequentially.
• Each dissociation has a unique Ka and pKa value.
Ka1 = [H+ ][HCO3 - ] / [H2CO3]
Ka2 = [H+ ][CO3 -2 ] / [HCO3- ]
Note: (The difference between a weak acid and its conjugate base differ is one hydrogen)