NEET MDS Synopsis
MAXILLARY FIRST BICUSPID
Dental Anatomy
MAXILLARY FIRST BICUSPID (PREMOLARS)
It is considered to be the typical bicuspid. (The word "bicuspid" means "having two cusps.")
Facial: The buccal surface is quite rounded and this tooth resembles the maxillary canine. The buccal cusp is long; from that cusp tip, the prominent buccal ridge descends to the cervical line of the tooth.
Lingual: The lingual cusp is smaller and the tip of that cusp is shifted toward the mesial. The lingual surface is rounded in all aspects.
Proximal: The mesial aspect of this tooth has a distinctive concavity in the cervical third that extends onto the root. It is called variously the mesial developmental depression, mesial concavity, or the 'canine fossa'--a misleading description since it is on the premolar. The distal aspect of the maxillary first permanent molar also has a developmental depression. The mesial marginal developmental groove is a distinctive feature of this tooth.
Occlusal: There are two well-defined cusps buccal and lingual. The larger cusp is the buccal; its cusp tip is located midway mesiodistally. The lingual cusp tip is shifted mesially. The occlusal outline presents a hexagonal appearance. On the mesial marginal ridge is a distinctive feature, the mesial marginal developmental groove.
Contact Points;The distal contact area is located more buccal than is the mesial contact area.
Root Surface:-The root is quite flat on the mesial and distal surfaces. In about 50 percent of maxillary first bicuspids, the root is divided in the apical third, and when it so divided, the tips of the facial and lingual roots are slender and finely tapered.
Bone Healing: Primary vs. Secondary Intention
Oral and Maxillofacial SurgeryBone Healing: Primary vs. Secondary Intention
Bone healing is a complex biological process that can occur through different
mechanisms, primarily classified into primary healing and secondary
healing (or healing by secondary intention). Understanding these
processes is crucial for effective management of fractures and optimizing
recovery.
Secondary Healing (Callus Formation)
Secondary healing is characterized by the
formation of a callus, which is a temporary fibrous tissue that bridges the
gap between fractured bone fragments. This process is often referred to as
healing by secondary intention.
Mechanism:
When a fracture occurs, the body initiates a healing response that
involves inflammation, followed by the formation of a soft callus
(cartilaginous tissue) and then a hard callus (bony tissue).
The callus serves as a scaffold for new bone formation and provides
stability to the fracture site.
This type of healing typically occurs when the fractured fragments
are approximated but not rigidly fixed, allowing for some movement at
the fracture site.
Closed Reduction: In cases where closed reduction is
used, the fragments are aligned but may not be held in a completely stable
position. This allows for the formation of a callus as the body heals.
Primary Healing (Direct Bone Union)
Primary healing occurs when the fractured
bone fragments are compressed against each other and held in place by rigid
fixation, such as with bone plates and screws. This method prevents the
formation of a callus and allows for direct bone union.
Mechanism:
In primary healing, the fragments are in close contact, allowing for
the migration of osteocytes and the direct remodeling of bone without
the intermediate formation of a callus.
This process is facilitated by rigid fixation, which stabilizes the
fracture and minimizes movement at the fracture site.
The healing occurs through a process known as Haversian
remodeling, where the bone is remodeled along lines of stress,
restoring its structural integrity.
Indications for Primary Healing:
Primary healing is typically indicated in cases of:
Fractures that are surgically stabilized with internal fixation
devices (e.g., plates, screws).
Fractures that require precise alignment and stabilization to
ensure optimal healing and function.
Group A Streptococcus
General Pathology
Group A Streptococcus
- scarlet fever usually begins as a Streptococcal pharyngitis/tonsillitis and then develops an erythematous rash beginning on the trunk and limbs with eventual desquamation.
- rash is due to elaboration of erythrogenic toxin by the organism
- face is usually spared, but, if involved there is a characteristic circumoral pallor and the tongue becomes bright red, thus the term "strawberry tongue".
- post-streptococcal immune complex glomerulonephritis is a possible sequela of scarlet fever.
- Dick test is a skin test that evaluates immunity against scarlet fever; no response indicates immunity (anti-toxin antibodies present); erythema indicates no immunity.
- impetigo due to Streptococcus pyogenes is characterized by honey colored, crusted lesions, while those with a predominantly bullous pattern are primarily due to Staphylococcus aureus.
- cellulitis with lymphangitis ("red streaks") is characteristic of Streptococcus pyogenes.
- hyaluronidase is a spreading factor that favors the spread of infection throughout the subcutaneous tissue unlike Staphylococcus aureus which generates coagulase to keep the pus confined.
- erysipelas refers to a raised, erythematous ("brawny edema"), hot cellulitis, usually on the face that commonly produces septicemia, if left untreated.
Pathogens Implicated in Periodontal Diseases
PeriodontologyPathogens Implicated in Periodontal Diseases
Periodontal diseases are associated with a variety of pathogenic
microorganisms. Below is a list of key pathogens implicated in different forms
of periodontal disease, along with their associations:
General Pathogens Associated with Periodontal Diseases
Actinobacillus actinomycetemcomitans:
Strongly associated with destructive periodontal disease.
Porphyromonas gingivalis:
A member of the "black pigmented Bacteroides group" and a
significant contributor to periodontal disease.
Bacteroides forsythus:
Associated with chronic periodontitis.
Spirochetes (Treponema denticola):
Implicated in various periodontal conditions.
Prevotella intermedia/nigrescens:
Also belongs to the "black pigmented Bacteroides group" and is
associated with several forms of periodontal disease.
Fusobacterium nucleatum:
Plays a role in the progression of periodontal disease.
Campylobacter rectus:
These organisms include members of the new genus Wolinella and are
associated with periodontal disease.
Principal Bacteria Associated with Specific Periodontal Diseases
Adult Periodontitis:
Porphyromonas gingivalis
Prevotella intermedia
Bacteroides forsythus
Campylobacter rectus
Refractory Periodontitis:
Bacteroides forsythus
Porphyromonas gingivalis
Campylobacter rectus
Prevotella intermedia
Localized Juvenile Periodontitis (LJP):
Actinobacillus actinomycetemcomitans
Capnocytophaga
Periodontitis in Juvenile Diabetes:
Capnocytophaga
Actinobacillus actinomycetemcomitans
Pregnancy Gingivitis:
Prevotella intermedia
Acute Necrotizing Ulcerative Gingivitis (ANUG):
Prevotella intermedia
Intermediate-sized spirochetes
Stimulants
Pharmacology
Stimulants:
Amphetamines: amphetamine is a substrate of serotonin and NE uptake transporters so in cytoplasm, it competes for transport into storage vesicles → ↑ [ ] in cytoplasm then excess amines bind to membrane transporter and are transported out of cell
Drugs:
a. Dextroamphetamine: psychomotor stimulant (↓ fatigue), short-term weight loss, prevents narcolepsy
b. Methylphenidate (Ritalin): prevents narcolepsy, treatment for ADD and ADHD
c. Methamphetamine: psychomotor stimulant, abused widely (cheap, easy to make)
Side effects:
a. CNS: euphoria, anxiety, agitation, delirium, paranoia, panic, suicidal/homicidal impulses, psychoses, tolerance (develops rapidly to most CNS effects), physical dependence (not clinically relevant)
b. CV: headache, chills, arrhythmias and HTN (may be fatal)
TCI -Target Controlled Infusion
Pharmacology
TCI -Target Controlled Infusion
TCI is an infusion system which allows the anaesthetist to select the target blood concentration required for a particular effect and then to control depth of anaesthesia by adjusting the requested target concentration
Mechanism
Instead of setting ml/h or a dose rate (mg/kg/h), the pump can be programmed to target a required blood concentration.
• Effect site concentration targeting is now included for certain pharmacokinetic models.
• The pump will automatically calculate how much is needed as induction and maintenance to maintain that concentration.
Herpetic Gingivostomatitis
PedodonticsHerpetic Gingivostomatitis
Herpetic gingivostomatitis is an infection of the oral cavity caused by the
herpes simplex virus (HSV), primarily HSV type 1. It is characterized by
inflammation of the gingiva and oral mucosa, and it is most commonly seen in
children.
Etiology and Transmission
Causative Agent: Herpes simplex virus (HSV).
Transmission: The virus is communicated through
personal contact, particularly via saliva. Common routes include:
Direct contact with an infected individual.
Transmission from mother to child, especially during the neonatal
period.
Epidemiology
Prevalence: Studies indicate that antibodies to HSV are
present in 40-90% of individuals across different populations, suggesting
widespread exposure to the virus.
Age of Onset:
The incidence of primary herpes simplex infection increases after 6
months of age, peaking between 2 to 5 years.
Infants under 6 months are typically protected by maternal
antibodies.
Clinical Presentation
Incubation Period: 3 to 5 days following exposure to
the virus.
Symptoms:
General Symptoms: Fever, headache, malaise, and
oral pain.
Oral Symptoms:
Initial presentation includes acute herpetic gingivostomatitis,
with the gingiva appearing red, edematous, and inflamed.
After 1-2 days, small vesicles develop on the oral mucosa, which
subsequently rupture, leading to painful ulcers with diameters of
1-3 mm.
Course of the Disease
Self-Limiting Nature: The primary herpes simplex
infection is usually self-limiting, with recovery typically occurring within
10 days.
Complications: In severe cases, complications may
arise, necessitating hospitalization or antiviral treatment.
Treatment
Supportive Care:
Pain management with analgesics for fever and discomfort.
Ensuring adequate hydration through fluid intake.
Topical anesthetic ointments may be used to facilitate eating and
reduce pain.
Severe Cases:
Hospitalization may be required for severe symptoms or
complications.
Antiviral agents (e.g., acyclovir) may be administered in severe
cases or for immunocompromised patients.
Recurrence of Herpetic Infections
Reactivation: Recurrent herpes simplex infections are
due to the reactivation of HSV, which remains dormant in nerve tissue after
the primary infection.
Triggers for Reactivation:
Mucosal injuries (e.g., from dental treatment).
Environmental factors (e.g., sunlight exposure, citrus fruits).
Location of Recurrence: Recurrent infections typically
occur at the same site as the initial infection, commonly manifesting as
herpes labialis (cold sores).
Cranial Nerves
Physiology
There Are 12 Pairs of Cranial Nerves
The 12 pairs of cranial nerves emerge mainly from the ventral surface of the brain
Most attach to the medulla, pons or midbrain
They leave the brain through various fissures and foramina of the skull
Nerve
Name
Sensory
Motor
Autonomic
Parasympathetic
I
Olfactory
Smell
II
Optic
Vision
III
Oculomotor
Proprioception
4 Extrinsic eye muscles
Pupil constriction
Accomodation
Focusing
IV
Trochlear
Proprioception
1 Extrinsic eye muscle (Sup.oblique)
V
Trigeminal
Somatic senses
(Face, tongue)
Chewing
VI
Abducens
Proprioception
1 Extrinsic eye muscle (Lat. rectus)
VII
Facial
Taste
Proprioception
Muscles of facial expression
Salivary glands
Tear glands
VIII
Auditory
(Vestibulocochlear)
Hearing, Balance
IX
Glossopharyngeal
Taste
Blood gases
Swallowing
Gagging
Salivary glands
X
Vagus
Blood pressure
Blood gases
Taste
Speech
Swallowing Gagging
Many visceral organs
(heart, gut, lungs)
XI
Spinal acessory
Proprioception
Neck muscles:
Sternocleidomastoid
Trapezius
XII
Hypoglossal
Proprioception
Tongue muscles
Speech
Many of the functions that make us distinctly human are controlled by cranial nerves: special senses, facial expression, speech.
Cranial Nerves Contain Sensory, Motor and Parasympathetic Fibers