NEET MDS Synopsis
The defecation reflex
PhysiologyThe defecation reflex:
As a result of the mass movements, pressure is exerted on the rectum and on the internal anal sphincter, which is smooth muscle, resulting in its involuntary relaxation. Afferent impulses are sent to the brain indicating the need to defecate. The external sphincter is voluntary muscle and is controlled by the voluntary nervous system. This sphincter is relaxed along with contraction of the rectal and abdominal muscles in the defecation reflex
Distraction Techniques
PedodonticsDistraction Techniques in Pediatric Dentistry
Distraction is a valuable technique used in pediatric dentistry to help
manage children's anxiety and discomfort during dental procedures. By diverting
the child's attention away from the procedure, dental professionals can create a
more positive experience and reduce the perception of pain or discomfort.
Purpose of Distraction
Divert Attention: The primary goal of distraction is to
shift the child's focus away from the dental procedure, which may be
perceived as unpleasant or frightening.
Reduce Anxiety: Distraction can help alleviate anxiety
and fear associated with dental visits, making it easier for children to
cooperate during treatment.
Enhance Comfort: Providing a break or a moment of
distraction during stressful procedures can enhance the overall comfort of
the child.
Techniques for Distraction
Storytelling:
Engaging the child in a story can capture their attention and
transport them mentally away from the dental environment.
Stories can be tailored to the child's interests, making them more
effective.
Counting Teeth:
Counting the number of teeth loudly can serve as a fun and
interactive way to keep the child engaged.
This technique can also help familiarize the child with the dental
procedure.
Repetitive Statements of Encouragement:
Providing continuous verbal encouragement can help reassure the
child and keep them focused on positive outcomes.
Phrases like "You're doing great!" or "Just a little longer!" can be
effective.
Favorite Jokes or Movies:
Asking the child to recall a favorite joke or movie can create a
light-hearted atmosphere and distract them from the procedure.
This technique can also foster a sense of connection between the
dentist and the child.
Audio-Visual Aids:
Utilizing videos, cartoons, or music can provide a visual and
auditory distraction that captures the child's attention.
Headphones with calming music or engaging videos can be particularly
effective during procedures like local anesthetic administration.
Application in Dental Procedures
Local Anesthetic Administration: Distraction techniques
can be especially useful during the administration of local anesthetics,
which may cause discomfort. Engaging the child in conversation or using
visual aids can help minimize their focus on the injection.
Example calculations of maximum local anesthetic doses for a 15-kg child
Pharmacology
Example calculations of maximum local anesthetic doses for a 15-kg child
Articaine
5 mg/kg maximum dose × 15 kg = 75 mg
4% articaine = 40 mg/mL
75 mg/(40 mg/mL) = 1.88 mL
1 cartridge = 1.8 mL
Therefore, 1 cartridge is the maximum
Lidocaine
7 mg/kg × 15 kg = 105 mg
2% lidocaine = 20 mg/mL
105 mg/(20 mg/mL) = 5.25 mL
1 cartridge = 1.8 mL
Therefore, 2.9 cartridges is the maximum
Mepivacaine
6.6 mg/kg × 15 kg = 99 mg
3% mepivacaine = 30 mg/mL
99 mg/(30 mg/mL) = 3.3 mL
1 cartridge = 1.8 mL
Therefore, 1.8 cartridges is the maximum.
Prilocaine
8 mg/kg × 15 kg = 120 mg
4% prilocaine = 40 mg/mL
120 mg/(40 mg/mL) = 3 mL
1 cartridge = 1.8 mL
Therefore, 1.67 cartridges is the maximum
Condensers/pluggers
Conservative DentistryCondensers/pluggers are instruments used to deliver the forces of compaction
to the underlying restorative material. There are
several methods for the application of these forces:
1.
Hand pressure: use of this method alone is contraindicated
except in a few situations like adapting the first piece of gold to
the convenience or point angles and where the line of force will not permit
use of other methods. Powdered golds are also
known to be better condensed with hand pressure. Small condenser points of
0.5 mm in diameter are generally
recommended as they do not require very high forces for their manipulation.
2.
Hand malleting: Condensation by hand malleting is a team work
in which the operator directs the condenser and moves it
over the surface, while the assistant provides rhythmic blows from the
mallet. Long handled condensers and leather faced
mallets (50 gms in weight) are used for this purpose. The technique allows
greater control and the condensers can be
changed rapidly when required. However, with the introduction of mechanical
malleting, use of this method has decreased
considerably.
3.
Automatic hand malleting: This method utilizes a spring loaded
instrument that delivers the desired force once the spiral
spring is released. (Disadvantage is that the blow descends very rapidly even
before full pressure has been exerted on the
condenser point.
4.
Electric malleting (McShirley electromallet): This instrument
accommodates various shapes of con-denser points and has a
mallet in the handle itself which remains dormant until wished by the
operator to function. The intensity or amplitude
generated can vary from 0.2 ounces to 15 pounds and the frequency can range
from 360-3600 cycles/minute.
5.
Pneumatic malleting (Hollenback condenser): This is the most
recent and satisfactory method first developed by
Dr. George M. Hollenback. Pneumatic mallets consist of vibrating nit
condensers and detachable tips run by
compressed air. The air is carried through a thin rubber tubing attached to
the hand piece. Controlling the air
pressure by a rheostat nit allows adjusting the frequency and amplitude of
condensation strokes. The construction
of the handpiece is such that the blow does not fall until pressure is placed
on the condenser point. This continues
until released. Pneumatic mallets are available with both straight and angled
for handpieces.
Antibiotic protocol for prevention of endocarditis from dental procedures
Oral Medicine
Antibiotic protocol for prevention of endocarditis from dental procedures
Local or no anaesthesia
- Oral amoxicillin 3 g 1 hour before procedure
- if allergic to penicillin or have had more than a single dose in previous month: oral clindamycin 600 mg 1 hour beforeprocedure
- patients who have had endocarditis: amoxicillin and gentamycin, as under general anaesthesia
General anaesthesia: no special risk
- Amoxicillin 1 g intravenous at induction, then oral amoxicillin 500 mg 6 hours later
- oral amoxicillin 3 g 4 hours before induction then oral amoxicillin 3 g as soon as possible after procedure
- oral amoxicillin 3 g and oral probenecid 1 g 4 hours before procedure
General anaesthesia: special risk
- Patients with a prosthetic valve or who have had endocarditis are at special risk
- Amoxicillin 1 g and gentomycin 120 mg both intravenous at induction, then oral amoxicillin 500 mg 6 hours later
General anaesthesia: penicillin not suitable
- Patients who are allergic to penicillin or who have received more than a single dose of a penicillin in the previous month need different antibiotic cover
- Vancomycin 1 g intravenous over at least 100 minutes then intravenous gentamycin 120 mg at induction or 15 minutes before procedure
- teicoplanin 400 mg and gentamycin 120 mg both intravenous at induction or 15 minutes before procedure
- clindamycin 300 mg intravenous over at least 10 minutes at induction or 15 minutes before procedure then oral or
intravenous clindamycin 150 mg 6 hours later
Meperidine
Pharmacology
Meperidine (Demerol)
Meperidine is a phenylpiperidine and has a number of congeners. It is mostly effective in the CNS and bowel
Produces analgesia, sedation, euphoria and respiratory depression.
Less potent than morphine, 80-100 mg meperidine equals 10 mg morphine.
Shorter duration of action than morphine (2-4 hrs).
Meperidine has greater excitatory activity than does morphine and toxicity may lead to convulsions.
Meperidine appears to have some atropine-like activity.
Does not constrict the pupils to the same extent as morphine.
Does not cause as much constipation as morphine.
Spasmogenic effect on GI and biliary tract smooth muscle is less pronounced than that produced by morphine.
Not an effective antitussive agent.
In contrast to morphine, meperidine increases the force of oxytocin-induced contractions of the uterus.
Often the drug of choice during delivery due to its lack of inhibitory effect on uterine contractions and its relatively short duration of action.
It has serotonergic activity when combined with monoamine oxidase inhibitors, which can produce serotonin toxicity (clonus, hyperreflexia, hyperthermia, and agitation)
Adverse reactions to Meperidine
• Generally resemble a combination of opiate and atropine-like effects.
- respiratory depression, - tremors, - delirium and possible convulsions, - dry mouth
• The presentation of mixed symptoms (stupor and convulsions) is quite common in addicts taking large doses of meperidine.
Fillers in Conservative Dentistry
Conservative DentistryFillers in Conservative Dentistry
Fillers play a crucial role in the formulation of composite resins used
in conservative dentistry. They are inorganic materials added to the organic
matrix to enhance the physical and mechanical properties of the composite. The
size and type of fillers significantly influence the performance of the
composite material.
1. Types of Fillers Based on Particle Size
Fillers can be categorized based on their particle size, which affects
their properties and applications:
Macrofillers: 10 - 100 µm
Midi Fillers: 1 - 10 µm
Minifillers: 0.1 - 1 µm
Microfillers: 0.01 - 0.1 µm
Nanofillers: 0.001 - 0.01 µm
2. Composition of Fillers
The dispersed phase of composite resins is primarily made up of
inorganic filler materials. Commonly used fillers include:
Silicon Dioxide
Boron Silicates
Lithium Aluminum Silicates
A. Silanization
Filler particles are often silanized to enhance bonding between the
hydrophilic filler and the hydrophobic resin matrix. This process improves
the overall performance and durability of the composite.
3. Effects of Filler Addition
The incorporation of fillers into composite resins leads to several
beneficial effects:
Reduces Thermal Expansion Coefficient: Enhances
dimensional stability.
Reduces Polymerization Shrinkage: Minimizes the
risk of gaps between the restoration and tooth structure.
Increases Abrasion Resistance: Improves the wear
resistance of the restoration.
Decreases Water Sorption: Reduces the likelihood
of degradation over time.
Increases Tensile and Compressive Strengths:
Enhances the mechanical properties, making the restoration more durable.
Increases Fracture Toughness: Improves the ability
of the material to resist crack propagation.
Increases Flexural Modulus: Enhances the stiffness
of the composite.
Provides Radiopacity: Allows for better
visualization on radiographs.
Improves Handling Properties: Enhances the
workability of the composite during application.
Increases Translucency: Improves the aesthetic
appearance of the restoration.
4. Alternative Fillers
In some composite formulations, quartz is partially replaced with heavy
metal particles such as:
Zinc
Aluminum
Barium
Strontium
Zirconium
A. Calcium Metaphosphate
Recently, calcium metaphosphate has been explored as a filler due
to its favorable properties.
B. Wear Considerations
These alternative fillers are generally less hard than traditional
glass fillers, resulting in less wear on opposing teeth.
5. Nanoparticles in Composites
Recent advancements have introduced nanoparticles into composite
formulations:
Nanoparticles: Typically around 25 nm in size.
Nanoaggregates: Approximately 75 nm, made from
materials like zirconium/silica or nano-silica particles.
A. Benefits of Nanofillers
The smaller size of these filler particles results in improved
surface finish and polishability of the restoration, enhancing both
aesthetics and performance.
Gingiva
Dental Anatomy
Gingiva
The connection between the gingiva and the tooth is called the dentogingival junction. This junction has three epithelial types: gingival, sulcular, and junctional epithelium. These three types form from a mass of epithelial cells known as the epithelial cuff between the tooth and the mouth.
Much about gingival formation is not fully understood, but it is known that hemidesmosomes form between the gingival epithelium and the tooth and are responsible for the primary epithelial attachment. Hemidesmosomes provide anchorage between cells through small filament-like structures provided by the remnants of ameloblasts. Once this occurs, junctional epithelium forms from reduced enamel epithelium, one of the products of the enamel organ, and divides rapidly. This results in the perpetually increasing size of the junctional epithelial layer and the isolation of the remenants of ameloblasts from any source of nutrition. As the ameloblasts degenerate, a gingival sulcus is created.