NEET MDS Synopsis
COMPOSITE RESINS -Reaction
Dental Materials
COMPOSITE RESINS
Reaction
Free radical polymerization
Monomers + initiator. + accelerators-+ polymer molecules
Initiators-start polymerization by decomposing and reacting with monomer
Accelerators-speed up initiator decomposition
Amines used for accelerating self –curing systems
Light used for accelerating light-curing systems
Retarders or inhibitors-prevent premature polymerization
The Skeleton of the Nose
AnatomyThe Skeleton of the Nose
The immovable bridge of the nose, the superior bony part of the nose, consists of the nasal bones, the frontal processes of the maxillae, and the nasal part of the frontal bones.
The movable cartilaginous part consists of five main cartilages and a few smaller ones.
The U-shaped alar nasal cartilages are free and movable.
They dilate and constrict the external nares when the muscles acting on the external nose contract.
The Nasal Cavities
The nasal cavities are entered through the anterior nares or nostrils.
They open into the nasopharynx through the choanae.
The Roof and Floor of the Nasal Cavity
The roof is curved and narrow, except at the posterior end.
The floor is wider than the roof.
It is formed from the palatine process of the maxilla and the horizontal plate of the palatine bone.
The Walls of the Nasal Cavity
The medial wall is formed by the nasal septum; it is usually smooth.
The lateral wall is uneven owing to the three longitudinal, scroll-shaped elevations, called the conchae (L. shells) or turbinates (L. shaped like a top).
These elevations are called the superior, middle and inferior conchae according to their position.
The superior and middle conchae are parts of the ethmoid bone, whereas the inferior conchae are separate bones.
The inferior and middle conchae project medially and inferiorly, producing air passageways called the inferior and middle meatus (L. passage). Note: the plural of "meatus" is the same as the singular.
The short superior conchae conceal the superior meatus.
The space posterosuperior to the superior concha is called the sphenoethmoidal recess.
Zygomatic Bone Reduction
General SurgeryZygomatic Bone Reduction
When performing a reduction of the zygomatic bone, particularly in the
context of maxillary arch fractures, several key checkpoints are used to assess
the success of the procedure. Here’s a detailed overview of the important
checkpoints for both zygomatic bone and zygomatic arch reduction.
Zygomatic Bone Reduction
Alignment at the Sphenozygomatic Suture:
While this is considered the best checkpoint for assessing the
reduction of the zygomatic bone, it may not always be the most practical
or available option in certain clinical scenarios.
Symmetry of the Zygomatic Arch:
Importance: This is the second-best checkpoint and
serves multiple purposes:
Maintains Interzygomatic Distance: Ensures that
the distance between the zygomatic bones is preserved, which is
crucial for facial symmetry.
Maintains Facial Symmetry and Aesthetic Balance:
A symmetrical zygomatic arch contributes to the overall aesthetic
appearance of the face.
Preserves the Dome Effect: The prominence of
the zygomatic arch creates a natural contour that is important for
facial aesthetics.
Continuity of the Infraorbital Rim:
A critical checkpoint indicating that the reduction is complete. The
infraorbital rim should show no step-off, indicating proper alignment
and continuity.
Continuity at the Frontozygomatic Suture:
Ensures that the junction between the frontal bone and the zygomatic
bone is intact and properly aligned.
Continuity at the Zygomatic Buttress Region:
The zygomatic buttress is an important structural component that
provides support and stability to the zygomatic bone.
Zygomatic Arch Reduction
Click Sound:
The presence of a click sound during manipulation can indicate
proper alignment and reduction of the zygomatic arch.
Symmetry of the Arches:
Assessing the symmetry of the zygomatic arches on both sides of the
face is crucial for ensuring that the reduction has been successful and
that the facial aesthetics are preserved.
Amoxicillin
Pharmacology
Amoxicillin
a moderate-spectrum
β-lactam antibiotic used to treat bacterial infections caused by susceptible
Mode of action Amoxicillin acts by inhibiting the synthesis of bacterial cell walls. It inhibits cross-linkage between the linear peptidoglycan polymer chains that make up a major component of the cell wall of Gram-positive bacteria. microorganisms. It is usually the drug of choice within the class because it is better absorbed, following oral administration, than other beta-lactam antibiotics. Amoxicillin is susceptible to degradation by β-lactamase-producing bacteria, and so is often given clavulanic acid.
Microbiology Amoxicillin is a moderate-spectrum antibiotic active against a wide range of Gram-positive, and a limited range of Gram-negative organisms
Susceptible Gram-positive organisms : Streptococcus spp., Diplococcus pneumoniae, non β-lactamase-producing Staphylococcus spp., and Streptococcus faecalis.
Susceptible Gram-negative organisms Haemophilus influenzae, Neisseria gonorrhoeae, Neisseria meningitidis, Escherichia coli, Proteus mirabilis and Salmonella spp.
Resistant organisms Penicillinase producing organisms, particularly penicillinase producing Staphylococcus spp. Penicillinase-producing N. gonorrhoeae and H. influenzae are also resistant
All strains of Pseudomonas spp., Klebsiella spp., Enterobacter spp., indole-positive
Proteus spp., Serratia marcescens, and Citrobacter spp. are resistant.
The incidence of β-lactamase-producing resistant organisms, including E. coli, appears to be increasing.
Amoxicillin and Clavulanic acid Amoxicillin is sometimes combined with clavulanic acid, a β-lactamase inhibitor, to increase the spectrum of action against
Gram-negative organisms, and to overcome bacterial antibiotic resistance mediated through β-lactamase production.
Classifications of epidemiologic research
Public Health Dentistry
Classifications of epidemiologic research
1. Descriptive research —involves description, documentation, analysis, and interpretation of data to evaluate a current event or situation
a. incidence—number of new cases of a specific disease within a defined population over a period of time
b. Prevalence—number of persons in a population affected by a condition at any one time
c. Count—simplest sum of disease: number of cases of disease occurrence
d. Proportion—use of a count with the addition of a denominator to determine prevalence:
does not include a time dimension: useful to evaluate prevalence of caries in schoolchildren or tooth loss in adult populations
e. Rate— uses a standardized denominator and includes a time dimension. for example. the number of deaths of newborn infants within first year of life per 1000 births
2. Analytical research—determines the cause of disease or if a causal relationship exists between a factor and a disease
a. Prospective study—planning of the entire study is completed before data are collected and analyzed; population is followed through time to determine which members develop the disease; several hypotheses may be tested at on time
b. Cohort study—individuals are classified into groups according to whether or not they pos- sess a particular characteristic thought to be related to the condition of interest; observations occur over time to see who develops dis ease or condition
c. Retrospective study— decision to carry out an investigation using observations or data that have been collected in the past; data may be incomplete or in a manner not appropriate for study
d. Cross-sectional study— study of subgroups of individuals in a specific and limited time frame to identify either initially to describe current status or developmental changes in the overall group from the perspective of what is typical in each subgroup
e. Longitudinal study—investigation of the same group of individuals over an extended period of time to identify a change or devel opment in that group
3. Experimental research—used when the etiology of the disease is established and the researcher wishes to determine the effectiveness of altering some factor or factors; deliberate applying or withholding of the supposed cause of a condition and observing the result
SPECIAL SOMATIC AFFERENT (SSA) PATHWAYS
Physiology
SPECIAL SOMATIC AFFERENT (SSA) PATHWAYS
Hearing
The organ of Corti with its sound-sensitive hair cells and basilar membrane are important parts of the sound transducing system for hearing. Mechanical vibrations of the basilar membrane generate membrane potentials in the hair cells which produce impulse patterns in the cochlear portion of the vestibulocochlear nerve (VIII)
Special somatic nerve fibers of cranial nerve VIII relay impulses from the sound receptors (hair cells) in the cochlear nuclei of the brainstem
These are bipolar neurons with cell bodies located in the spiral ganglia of the cochlea.
Vestibular System
The vestibulocochlear nerve serves two quite different functions.
The cochlear portion, conducts sound information to the brain,
The vestibular portion conducts proprioceptive information.
It is the central neural pathways
Special somatic afferent fibers from the hair cells of the macula utriculi and macula sacculi conduct information into the vestibular nuclei on the ipsilateral side of the pons and medulla.
These are bipolar neurons with cell bodies located in the vestibular ganglion.
Some of the fibers project directly into the ipsilateral cerebellum to terminate in the uvula, flocculus, and nodulus, but most enter the vestibular nuclei and synapse there.
Vision
The visual system receptors are the rods and cones of the retina.
Special somatic afferent fibers of the optic nerve (II) conduct visual signals into the brain
Fibers from the lateral (temporal) retina of either eye terminate in the lateral geniculate body on the same side of the brain as that eye.
SSA II fibers from the medial (nasal) retina of each eye cross over in the optic chiasm to terminate in the contralateral lateral geniculate body.
Area 17 is the primary visual area, which receives initial visual signals.
Neurons from this area project into the adjacent occipital cortex (areas 18 and 19) which is known as the secondary visual area. It is here that the visual signal is fully evaluated.
The visual reflex pathway involving the pupillary light reflex - in which the pupils constrict when a light is shined into the eyes and dilate when the light is removed.
Some SSA II fibers leave the optic tract before reaching the lateral geniculates, terminating in the superior colliculi instead.
From here, short neurons project to the EdingerWestphal nucleus (an accessory nucleus of III) in the midbrain, which serves as the origin of the preganglionic parasympathetic fibers of the oculomotor nerve (GVE III).
The GVE III fibers in turn project to the ciliary ganglia, from which arise the postganglionic fibers to the sphincter muscles of the iris, which constrict the pupils.
Graves disease
General Pathology
Graves disease
Graves disease is an organ-specific autoimmune disorder that results in thyrotoxicosis due to overstimulation of the thyroid gland by autoantibodies.
- It is the most common form of thyrotoxicosis, females being affected more than males by 8: 1.
- It is usually associated with a diffuse enlargement of the thyroid.
Pathogenesis
IgG-type immunoglobulins bind to TSH membrane receptors and cause prolonged stimulation of the thyroid, lasting for as long as 12 hours
(cf. 1 hour for TSH). The autoantibody binds at a site different to the hormone-binding locus and is termed the TSH-receptor autoantibody (TRAb); 95% of Graves’ disease patients are positive for TRAbs
Gross features
- The thyroid gland is diffusely and moderately enlarged
- It is usually smooth, soft, and congested
Histologically
- the gland shows diffuse hypertrophy and hyperplasia of acinar epithelium, reduction of stored colloid and local accumulations of lymphocytes with lymphoid follicle formation.
Clinical features
- Exophthalmos (protrusion of the eyeballs in their sockets)—due to the infiltration of orbital tissues by fat, mucopolysaccharides and lymphocytes. May cause compression of the optic nerve, hence blindness. However, only about 5% of Graves’ patients show signs of exophthalmos.
- Thyroid acropachy—enlargement of fingernails.
- Pretibial myxoedema—accumulation of mucoproteins in the deep dermis of the skin.
Treatment is as for thyrotoxicosis.
Psychosocial Traits and Skills
PedodonticsAge-Related Psychosocial Traits and Skills for 2- to 5-Year-Old Children
Understanding the psychosocial development of children aged 2 to 5 years is
crucial for parents, educators, and healthcare providers. This period is marked
by significant growth in motor skills, social interactions, and language
development. Below is a breakdown of the key traits and skills associated with
each age group within this range.
Two Years
Motor Skills:
Focused on gross motor skills, such as running and jumping.
Sensory Exploration:
Children are eager to see and touch their environment, engaging in
sensory play.
Attachment:
Strong attachment to parents; may exhibit separation anxiety.
Play Behavior:
Tends to play alone and rarely shares toys or space with others
(solitary play).
Language Development:
Limited vocabulary; beginning to form simple sentences.
Self-Help Skills:
Starting to show interest in self-help skills, such as dressing or
feeding themselves.
Three Years
Social Development:
Less egocentric than at two years; begins to show a desire to please
others.
Imagination:
Exhibits a very active imagination; enjoys stories and imaginative
play.
Attachment:
Continues to maintain a close attachment to parents, though may
begin to explore social interactions with peers.
Four Years
Power Dynamics:
Children may try to impose their will or power over others, testing
boundaries.
Social Interaction:
Participates in small social groups; begins to engage in parallel
play (playing alongside peers without direct interaction).
Expansive Period:
Reaches out to others; shows an interest in making friends and
socializing.
Independence:
Demonstrates many independent self-help skills, such as dressing and
personal hygiene.
Politeness:
Begins to understand and use polite expressions like "thank you" and
"please."
Five Years
Consolidation:
Undergoes a period of consolidation, where skills and behaviors
become more deliberate and refined.
Pride in Possessions:
Takes pride in personal belongings and may show attachment to
specific items.
Relinquishing Comfort Objects:
Begins to relinquish comfort objects, such as a blanket or
thumb-sucking, as they gain confidence.
Cooperative Play:
Engages in cooperative play with peers, sharing and taking turns,
which reflects improved social skills and emotional regulation.