Wednesday, May 9, 2012
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Friday, April 6, 2012
splinting of teeth
Splinting:
It is defined as the joining of two or more teeth with a rigid unit by means of fixed or removable restorations.
Splint :
It is defined as an appliance used for immobilization of injured or diseased parts.
Requirements of an Ideal Splint:
It should allow direct application in the mouth without delay due to laboratory procedures.
It should not traumatize the tooth during application.
It should immobilize the injured tooth in a normal position.
It should provide adequate fixation throughout the entire period of immobilization.
It should neither damage the gingiva nor predispose to caries.
It should not interfere with occlusion.
It should not interfere with endodontic treatment.
It should fulfill aesthetic demands.
What are the different Types of Splints:
Fixed Splints
Removable Splints
For detailed information of Types of Splinting Click here - “Types of Dental Splints”
·
What are the Objectives Of Splinting:
It provides rest .
For redirection of forces : Forces of occlusion are redirected in a more axial direction over all the teeth included in the splint .
For redistribution of forces: Redistribution ensures that forces do not exceed adaptive capacity .
To preserve arch integrity: Splinting restores proximal contacts reducing food impaction & consequent breakdown .
Restoration of functional stability: Restores a functional occlusion , stabilizes the mobile teeth & increases masticatory comfort .
Psychologic well being: Gives the patient comfort from mobile teeth thereby giving him the sense of well being .
Indications:
It is used in the treatment of dento-alveolar & mandibular fractures .
It stabilizes moderate to advanced tooth mobility that cannot be reduced by other means .
It stabilizes teeth after acute dental trauma .Ex: Subluxation .
Contraindications:
Insufficient number of firm or sufficiently firm teeth to stabilize mobile teeth .
Prior occlusal adjustment cannot be done on teeth with occlusal trauma or occlusal interference .
Patients who don’t maintain good oral hygiene.
What are the Objectives Of Splinting:
It provides rest .
For redirection of forces : Forces of occlusion are redirected in a more axial direction over all the teeth included in the splint .
For redistribution of forces: Redistribution ensures that forces do not exceed adaptive capacity .
To preserve arch integrity: Splinting restores proximal contacts reducing food impaction & consequent breakdown .
Restoration of functional stability: Restores a functional occlusion , stabilizes the mobile teeth & increases masticatory comfort .
Psychologic well being: Gives the patient comfort from mobile teeth thereby giving him the sense of well being .
Indications:
It is used in the treatment of dento-alveolar & mandibular fractures .
It stabilizes moderate to advanced tooth mobility that cannot be reduced by other means .
It stabilizes teeth after acute dental trauma .Ex: Subluxation .
Contraindications:
Insufficient number of firm or sufficiently firm teeth to stabilize mobile teeth .
Prior occlusal adjustment cannot be done on teeth with occlusal trauma or occlusal interference .
Patients who don’t maintain good oral hygiene.
bacteria
Archaebacteria and
Eubacteria
Bacteria are of immense importance
because of their rapid growth, reproduction, and mutation rates, as well as,
their ability to exist under adverse conditions.
The oldest fossils known, nearly
3.5 billion years old, are fossils of bacteria-like organisms.
Bacteria can be autotrophs or
hetertrophs.
Those that are classified as autotrophs
are either photosynthetic, obtaining energy from sunlight or chemosynthetic, breaking down
inorganic substances for energy .
Bacteria classified as heterotrophs
derive energy from breaking down complex organic compounds in the
environment. This includes saprobes,
bacteria that feed on decaying material and organic wastes, as well as
those that live as parasites, absorbing nutrients from living organisms.
Depending on the species, bacteria
can be aerobic which means they require oxygen to live
or
anaerobic which means oxygen
is deadly to them.
Archaebacteria
Methanogens
These
Archebacteria are anaerobes. They make methane (natural gas) as a
waste product. They are found in swamp sediments, sewage, and in buried
landfills. In the future, they could be used to produce methane as a byproduct
of sewage treatment or landfill operation.
Halophiles
These
are salt-loving Archaebacteria that grow in places like the Great Salt Lake of
Utah or salt ponds on the edge of San Francisco Bay. Large numbers of certain
halophiles can turn these waters a dark pink. Pink halophiles contain a pigment
very similar to the rhodopsin in the human retina. They use this visual pigment
for a type of photosynthesis that does not produce oxygen. Halophiles are
aerobes, however, and perform aerobic respiration.
Thermophiles
These
are Archaebacteria from hot springs and other high temperature environments.
Some can grow above the boiling temperature of water. They are anaerobes,
performing anaerobic respiration.
Thermophiles are interesting because they contain genes for
heat-stable enzymes that may be of great value in industry and medicine. An
example is taq polymerase, the gene for which was isolated from a collection of
Thermus aquaticus in a Yellowstone Park hot spring. Taq polymerase is
used to make large numbers of copies of DNA sequences in a DNA sample. It is
invaluable to medicine, biotechnology, and biological research. Annual sales of
taq polymerase are roughly half a billion dollars.
Eubacteria
Cyanobacteria
This is
a group of bacteria that includes some that are single cells and some that are
chains of cells. You may have seen them as "green slime" in your
aquarium or in a pond.
Cyanobacteria can do "modern photosynthesis",
which is the kind that makes oxygen from water. All plants do this kind of
photosynthesis and inherited the ability from the cyanobacteria.
Bacteria are often maligned as the
causes of human and animal disease.
However, certain bacteria, the actinomycetes, produce antibiotics such
as streptomycin and nocardicin.
Other Bacteria live symbiotically
in the guts of animals or elsewhere in their bodies.
For example, bacteria in your gut
produce vitamin K which is essential to blood clot formation.
Still other Bacteria live on the
roots of certain plants, converting nitrogen into a usable form.
Bacteria put the tang in yogurt and
the sour in sourdough bread.
Saprobes help to break down dead
organic matter.
Bacteria make up the base of the
food web in many environments.
Bacteria are prokaryotic and
unicellular.
Bacteria have cell walls.
Bacteria have circular DNA called plasmids
Bacteria can be anaerobes or
aerobes.
Bacteria are heterotrophs or autotrophs.
Bacteria are awesome!
Bacteria can reproduce sexually by conjugation
or asexually by binary fission.
Endospore
Bacteria can survive unfavorable
conditions by producing an endospore.
Shapes of Bacteria
Penicillin kills bacteria by making
holes in their cell walls. Unfortunately, many bacteria have developed
resistance to this antibiotic.
The Gram stain, which
divides most clinically significant bacteria into two main groups, is the first
step in bacterial identification.
Bacteria stained purple are Gram + -
their cell walls have thick petidoglycan and
teichoic acid.
Bacteria stained pink are Gram – their
cell walls have have thin peptidoglycan and
lipopolysaccharides with no teichoic acid.
The Gram stain has four steps:
1. crystal violet, the primary
stain: followed by
2. iodine, which acts as a mordant
by forming a crystal violet-iodine complex, then
3. alcohol, which decolorizes,
followed by
4. safranin, the counterstain.
Is this gram stain positive or
negative?
Identify the bacteria.
Identify the bacteria.
Gram staining tests the bacterial
cell wall's ability to retain crystal violet dye during solvent
treatment.
Safranin is added as a mordant to
form the crystal violet/safranin complex in order to render the dye
impossible to remove.
Ethyl-alcohol solvent acts as a
decolorizer and dissolves the lipid layer from gram-negative cells. This
enhances leaching of the primary stain from the cells into the surrounding
solvent.
Ethyl-alcohol will dehydrate the thicker
gram-positive cell walls, closing the pores as the cell wall shrinks.
For this reason, the diffusion of
the crystal violet-safranin staining is inhibited, so the bacteria remain
stained.
tetanus
Tetanus
Brief history of disease
5th century BC: Hippocrates first described
the disease
1884: Carle and Rattone discovered the etiology
(cause/origin of disease)
p
Produced tetanus by injecting pus from a
fatal human case
p
Nicolaier was able to do the same by
injecting soil samples into animals
1889: Kitasato isolated the organism from
human victim, showed that it could produce disease when injected into animals.
Reported that toxin could be neutralized by specific antibodies.
1897: Nocard demonstrated the protective
effect of passively transferred antitoxin Ã
used in WWI
1924: Descombey developed tetanus toxoid for active
immunization Ã
used in WWII
Causative agent
Clostridium tetani
Morphology & Physiology
Relatively
large, Gram-positive, rod-shaped bacteria
Spore-forming, anaerobic.
Found in soil, especially
heavily-manured soils, and in the intestinal tracts and feces of various
animals.
Strictly fermentative mode of
metabolism.
Virulence & Pathogenicity
Not pathogenic to humans and
animals by invasive infection but by the production of a potent protein toxin
tetanus toxin or tetanospasmin
The second exotoxin produced is
tetanolysin—function not known.
Tetanus toxin
Produced when spores germinate
and vegetative cells grow after gaining access to wounds. The organism
multiplies locally and symptoms appear remote from the infection site.
One of the three most poisonous
substances known on a weight basis, the other two being the toxins of botulism
and diphtheria.
n
Tetanus toxin is produced in vitro in amounts
up to 5 to 10% of the bacterial weight.
n
Estimated lethal human dose of Tetanospamin =
2.5 nanograms/kg body
Because the toxin has a specific affinity for
nervous tissue, it is referred to as a neurotoxin. The toxin has no known
useful function to C. tetani.
Initially binds to peripheral nerve terminals
Transported within the axon and across
synaptic junctions until it reaches the central nervous system.
Becomes rapidly fixed to gangliosides at the
presynaptic inhibitory motor nerve endings, then taken up into the axon by
endocytosis.
Methods of
transmission
C. tetani can live for
years as spores in animal feces and soil. As soon as it enters the human body
through a major or minor wound and the conditions are anaerobic, the spores
germinate and release the toxins.
Tetanus may follow burns, deep
puncture wounds, ear or dental infections, animal bites, abortion.
Only the growing bacteria can
produce the toxin.
It is the only vaccine-preventable
disease that is infectious but not contagious from person to person.
Symptoms
Tetanic
seizures (painful, powerful bursts of muscle contraction)
if
the muscle spasms affect the larynx or chest wall, they may cause asphyxiation
stiffness
of jaw (also called lockjaw)
stiffness
of abdominal and back muscles
contraction
of facial muscles
fast
pulse
fever
sweating
Types of tetanus:
local, cephalic, generalized, neonatal
Incubation
period: 3-21 days, average 8 days.
Uncommon types:
Local
tetanus: persistent muscle contractions in the same anatomic area as the
injury, which will however subside after many weeks; very rarely fatal; milder
than generalized tetanus, although it could precede it.
Cephalic
tetanus: occurs with ear infections or following injuries of the head;
facial muscles contractions.
Most
common types:
Generalized tetanus
-
descending pattern: lockjaw à stiffness of neck à difficulty swallowing à rigidity of abdominal
and back muscles.
-
Spasms continue for 3-4 weeks, and recovery can
last for months
-
Death occurs when spasms interfere with
respiration.
Neonatal tetanus:
-
Form of generalized tetanus that occurs in
newborn infants born without protective passive immunity because the mother is
not immune.
-
Usually occurs through infection of the unhealed
umbilical stump, particularly when the stump is cut with an unsterile
instrument.
Methods
of diagnosis
Based
on the patient’s account and physical findings that are characteristic of the
disease.
Diagnostic
studies generally are of little value, as cultures of the wound site are
negative for C. tetani two-thirds of the time.
n When
the culture is positive, it confirms the diagnosis of tetanus
Tests
that may be performed include the following:
n Culture
of the wound site (may be negative even if tetanus is present)
n Tetanus
antibody test
n Other
tests may be used to rule out meningitis, rabies, strychnine poisoning, or
other diseases with similar symptoms.
Clinical
treatment
If
treatment is not sought early, the disease is often fatal.
The
bacteria are killed with antibiotics, such as penicillin or
tetracycline; further toxin production is thus prevented.
The
toxin is neutralized with shots of tetanus immune globulin, TIG.
Other
drugs may be given to provide sedation, relax the muscles and relieve pain.
Due
to the extreme potency of the toxin, immunity does not result after the disease.
Method
of prevention - immunization
A
person recovering from tetanus should begin active immunization with tetanus
toxoid (Td) during convalescence.
The
tetanus toxoid is a formalin-inactivated toxin, with an efficiency of approx.
100%.
The
DTaP vaccine includes tetanus, diphteria and pertussis toxoids; it is routinely
given in the US during childhood. After 7 years of age, only Td needs to be
administered.
Because
the antitoxin levels decrease over time, booster immunization shots are needed
every 10 years.
What else can be
done?
Remove
and destroy the source of the toxin through surgical exploration and cleaning
of the wound (debridement).
Bedrest
with a nonstimulating environment (dim light, reduced noise, and stable
temperature) may be recommended.
Sedation
may be necessary to keep the affected person calm.
Respiratory
support with oxygen, endotracheal tube, and mechanical ventilation may be
necessary.
points on pharmacology
1drug used in cysticercosis :- prazequental
2 most vunerable period of pregnancy for the causation of foetal malformation is:- 19-55 days
3 a patient on digoxine should not be given qunidine because it displaces digoxin from its protein binding site
4 potassium sparing diurtics are contraindicated because they can causes hyperkelimia which may causes cardiac depression
5 stage lll plane 3 general anesthesia surgery is done
6 phenothiazine causes extrapyramidal symtoms
7 the rate of injection of IV. valium is 1ml/min
8 doxacurium a recently introduse muscle relaxant has longest duration of action
9
piroxicame is rapidly and completly absorb entrohepatic cycling occure
plasma t1/2 is long nearly 2 days single daily adminstration is
sufficient .
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