NEET MDS Synopsis
COMPOSITE RESINS - Finishing and Polishing
Dental Materials
Finishing and Polishing
Remove oxygen-inhibited layer .Use stones or carbide burs for gross reduction.Use highly fluted carbide burs or special diamonds for fine reduction.Use aluminum oxide strips or disks for finishing. Use fine aluminum oxide finishing pastes. Microfills develop smoothest finish because of small size of filler particles
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.
Dental Calculus
Periodontology
Dental Calculus
Dental calculus, also known as tartar, is a hard deposit that forms on teeth
due to the mineralization of dental plaque. Understanding the composition and
crystal forms of calculus is essential for dental professionals in diagnosing
and managing periodontal disease.
Crystal Forms in Dental Calculus
Common Crystal Forms:
Dental calculus typically contains two or more crystal forms. The
most frequently detected forms include:
Hydroxyapatite:
This is the primary mineral component of both enamel and
calculus, constituting a significant portion of the calculus
sample.
Hydroxyapatite is a crystalline structure that provides
strength and stability to the calculus.
Octacalcium Phosphate:
Detected in a high percentage of supragingival calculus
samples (97% to 100%).
This form is also a significant contributor to the bulk of
calculus.
Other Crystal Forms:
Brushite:
More commonly found in the mandibular anterior region of the
mouth.
Brushite is a less stable form of calcium phosphate and may
indicate a younger calculus deposit.
Magnesium Whitlockite:
Typically found in the posterior areas of the mouth.
This form may be associated with older calculus deposits and can
indicate changes in the mineral composition over time.
Variation with Age:
The incidence and types of crystal forms present in calculus can
vary with the age of the deposit.
Younger calculus deposits may have a higher proportion of brushite,
while older deposits may show a predominance of hydroxyapatite and
magnesium whitlockite.
Clinical Significance
Understanding Calculus Formation:
Knowledge of the crystal forms in calculus can help dental
professionals understand the mineralization process and the conditions
under which calculus forms.
Implications for Treatment:
The composition of calculus can influence treatment strategies. For
example, older calculus deposits may be more difficult to remove due to
their hardness and mineral content.
Assessment of Periodontal Health:
The presence and type of calculus can provide insights into a
patient’s oral hygiene practices and periodontal health. Regular
monitoring and removal of calculus are essential for preventing
periodontal disease.
Research and Development:
Understanding the mineral composition of calculus can aid in the
development of new dental materials and treatments aimed at preventing
calculus formation and promoting oral health.
Dental Plaque
PeriodontologyDental Plaque
Dental plaque is a biofilm that forms on the surfaces of teeth and is
composed of a diverse community of microorganisms. The development of dental
plaque occurs in stages, beginning with primary colonizers and progressing to
secondary colonization and plaque maturation.
Primary Colonizers
Timeframe:
Acquired within a few hours after tooth cleaning or exposure.
Characteristics:
Predominantly gram-positive facultative microbes.
Key Species:
Actinomyces viscosus
Streptococcus sanguis
Adhesion Mechanism:
Primary colonizers adhere to the tooth surface through specific
adhesins.
For example, A. viscosus possesses fimbriae that bind to
proline-rich proteins in the dental pellicle, facilitating initial
attachment.
Secondary Colonization and Plaque Maturation
Microbial Composition:
As plaque matures, it becomes predominantly populated by
gram-negative anaerobic microorganisms.
Key Species:
Prevotella intermedia
Prevotella loescheii
Capnocytophaga spp.
Fusobacterium nucleatum
Porphyromonas gingivalis
Coaggregation:
Coaggregation refers to the ability of different species and genera
of plaque microorganisms to adhere to one another.
This process occurs primarily through highly specific stereochemical
interactions of protein and carbohydrate molecules on cell surfaces,
along with hydrophobic, electrostatic, and van der Waals forces.
Plaque Hypotheses
Specific Plaque Hypothesis:
This hypothesis posits that only certain types of plaque are
pathogenic.
The pathogenicity of plaque depends on the presence or increase of
specific microorganisms.
It predicts that plaque harboring specific bacterial pathogens leads
to periodontal disease due to the production of substances that mediate
the destruction of host tissues.
Nonspecific Plaque Hypothesis:
This hypothesis maintains that periodontal disease results from the
overall activity of the entire plaque microflora.
It suggests that the elaboration of noxious products by the entire
microbial community contributes to periodontal disease, rather than
specific pathogens alone.
TRICYCLIC ANTIDEPRESSANTS
Pharmacology
TRICYCLIC ANTIDEPRESSANTS
e.g. amitriptyline, imipramine, nortriptyline
Belong to first generation antidepressants
ACTION:
Inhibit 5-HT(5-hydroxytryptamine) and norepinephrine reuptake
slow clearance of norepinephrine & 5-HT from the synapse
enhance norepinephrine & 5-HT neuro-transmission
MODE OF ACTIONMODE OF ACTION
TCAs also block
– muscarinic acetylcholine receptors
– histamine receptors
– 5-HT receptors
– α1 adrenoceptors
Onset of antidepressant activity takes 2-3 weeks
PHARMACOKINETICS
- Readily absorbed from the gastro-intestinal tract
- Bind strongly to plasma albumin
- Has a large volume of distribution(as a result of binding to extravascular tissues)
- Undergo liver CYP metabolism into biologically active metabolites
- These metabolites are inactivated via glucuronidation and excreted in urine
ADVERSE DRUG REACTIONS
Antimuscarinic - dry mouth, blurred vision, constipation and urinary retention
Antihistamine – drowsiness
adrenoceptor blockage(+/- central effect) postural hypotension
Reduce seizure threshold
Testicular enlargement, gynaecomastia, galactorrhoea
AV-conduction blocks and cardiac arrhythmias
TOXICITY
- Fatal in toxicity
- Most important toxic effect is, slowing of depolarisation of the cardiac action potential by blocking fast sodium channels ("quinidine-like" effect)
- delays propagation of depolarisation through both myocardium and conducting tissue
- prolongation of the QRS complex and the PR/QT intervals
- predisposition to cardiac arrhythmias
DRUG INTERACTIONS
Pharmacodynamic:
– ↑ sedation with antihistamines, alcohol
– ↑ antimuscarinic effects with anticholinergics– ↑ antimuscarinic effects with anticholinergics
– Hypertension and arrhythmias with MAOIs- should be given at least 14 days apart
Pharmacokinetic (via altering CYP metabolism)
– ↓ plasma concentration of TCA by- carbamazepine, rifampicin
– ↑ plasma concentration of TCA by- cimetidine, calcium channel blockers,fluoxetine
OTHER CLINICAL USES OF AMITRIPTYLINE
- Treatment of nocturnal enuresis in children
- Treatment of neuropathic pain
- Migraine prophylaxis
Muscles of the Tongue
Anatomy
The tongue is divided into halves by a medial fibrous lingual septum that lies deep to the medial groove.
In each half of the tongue there are four extrinsic and four intrinsic muscles.
The lingual muscles are all supplied by the hypoglossal nerve (CN XII).
The only exception is palatoglossus, which is supplied by the pharyngeal branch of the vagus nerve, via the pharyngeal plexus.
Flucloxacillin
Pharmacology
Flucloxacillin, important even now for its resistance to beta-lactamases produced by bacteria such as Staphylococcus species. It is still no match for MRSA (Methicillin Resistant Staphylococcus aureus).
The last in the line of true penicillins were the antipseudomonal penicillins, such as ticarcillin, useful for their activity against Gram-negative bacteria
TRACHEOSTOMY TUBES
Surgery
TYPES OF TRACHEOSTOMY TUBE
A tracheostomy tube may be metallic or nonmetallic
Metallic Tracheostomy Tube
Metallic tubes are formed from the alloy of silver, copper and phosphorus
Example Jackson’s Tracheostomy tube.
Has an inner and an outer tube.The inner tube is longer than the outer one so that secretions and crusts formed in it can be removed and the tube reinserted after cleaning without difficulty. However, they do not have a cuff and cannot produce an airtight seal.
Advantages of a double lumen tracheostomy tube are easy to remove,clean and replace inner cannula.
Inner cannula should be removed and cleaned as and when indicated for the first 3 days. Outer tube, unless blocked or displaced, should not be removed for 3-4 days to allow a track to be formed when tube placement will be easy.
Nonmetallic Tracheostomy Tube
Can be of cuffed or noncuffed variety, e.g. rubber and PVC tubes.
Cuffed Tracheostomy Tubes
Pediatric tubes do not have a cuff.
Cuffed tubes are used in situation where positive pressure ventilation is required, or when the airway is at risk from aspiration. (In unconscious patient or when patient is on respiration).
The cuff should be deflated every 2 hours for 5 mins to present pressure damage to the trachea.
Uncuffed Tracheostomy Tubes
It is suitable for a patient who has returned to the ward from a prolonged stay in intensive care and requires physiotherapy and suction via trachea.
This type of tube is not suitable for patients who are unable to swallow due to incompetent laryngeal reflexes, and aspiration of oral or gastric contents is likely to occur.
An uncuffed tube is advantageous in that it allows the patient to breathe around it in the event of the tube becoming blocked. Patients can also speak with an uncuffed tube.
Important
Nonmetallic Tracheostomy Tube - Cuffed tubes are used in situation where positive pressure ventilation is required, or when the airway is at risk from aspiration. (In unconscious patient or when patient is on respiration).
Metallic Tracheostomy Tube -Metallic tubes are formed from the alloy of silver, copper and phosphorus .
Example Jackson’s Tracheostomy tube.
Advantages of a double lumen tracheostomy tube are easy to remove,clean and replace inner cannula.