NEET MDS Synopsis
Lip Bumper
OrthodonticsLip Bumper
A lip bumper is an orthodontic appliance designed to create
space in the dental arch by preventing the lips from exerting pressure on the
teeth. It is primarily used in growing children and adolescents to manage dental
arch development, particularly in cases of crowding or to facilitate the
eruption of permanent teeth. The appliance is typically used in the lower arch
but can also be adapted for the upper arch.
Indications for Use
Crowding:
To create space in the dental arch for the proper alignment of
teeth, especially when there is insufficient space for the eruption of
permanent teeth.
Anterior Crossbite:
To help correct anterior crossbites by allowing the anterior teeth
to move into a more favorable position.
Eruption Guidance:
To guide the eruption of permanent molars and prevent them from
drifting mesially, which can lead to malocclusion.
Preventing Lip Pressure:
To reduce the pressure exerted by the lips on the anterior teeth,
which can contribute to dental crowding and misalignment.
Space Maintenance:
To maintain space in the dental arch after the premature loss of
primary teeth.
Design and Features
Components:
The lip bumper consists of a wire framework that is typically made
of stainless steel or other durable materials. It includes:
Buccal Tubes: These are attached to the molars
to anchor the appliance in place.
Arch Wire: A flexible wire that runs along the
buccal side of the teeth, providing the necessary space and support.
Lip Pad: A soft pad that rests against the
lips, preventing them from exerting pressure on the teeth.
Customization:
The appliance is custom-fitted to the patient’s dental arch to
ensure comfort and effectiveness. Adjustments can be made to accommodate
changes in the dental arch as treatment progresses.
Mechanism of Action
Space Creation:
The lip bumper creates space in the dental arch by pushing the
anterior teeth backward and allowing the posterior teeth to erupt
properly. The lip pad prevents the lips from applying pressure on the
anterior teeth, which can help maintain the space created.
Guiding Eruption:
By maintaining the position of the molars and preventing mesial
drift, the lip bumper helps guide the eruption of the permanent molars
into their proper positions.
Facilitating Growth:
The appliance can also promote the growth of the dental arch,
allowing for better alignment of the teeth as they erupt.
Transient structures during tooth development
Dental Anatomy
Transient structures during tooth development
Enamel knot: Thickening of the internal dental epithelium at the center of the dental organ.
Enamel cord: Epithelial proliferation that seems to divide the dental organ in two.
Review the role of these two structures
Enamel niche: It is an artifact that is produced during section of the tissue. It occurs because the dental organ is a sheet of proliferating cells rather than a single strand. It looks like a concavity that contains ectomesenchyme.
Multiple sclerosis
General Pathology
Multiple sclerosis
a. A demyelinating disease that primarily affects myelin (i.e. white matter). This affects the conduction of electrical impulses along the axons of nerves. Areas of demyelination are known as plaques.
b. The most common demyelinating disease.
c. Onset of disease usually occurs between ages 20 and 50; slightly more common in women.
d. Disease can affect any neuron in the central nervous system, including the brainstem and spinal cord. The optic nerve (vision) is commonly affected.
Role of Coenzymes
Biochemistry
Role of Coenzymes
The functional role of coenzymes is to act as transporters of chemical groups from one reactant to another.
Ex. The hydride ion (H+ + 2e-) carried by NAD or the mole of hydrogen carried by FAD;
The amine (-NH2) carried by pyridoxal phosphate
Acute pericarditis
General Pathology
Acute pericarditis
1. Characterized by inflammation of the pericardium.
2. Causes include:
a. Viral infection.
b. Bacterial infection, including Staphylococcus, Pneumococcus.
c. Tuberculosis.
d. MI.
e. Systemic lupus erythematosus.
f. Rheumatic fever.
3. Signs and symptoms include:
a. Pericardial friction rub on cardiac auscultation.
b. Angina.
c. Fever.
4. Consequences include constrictive pericarditis,which results from fusion and scarring of the pericardium. This may lead to the restriction of ventricular expansion, preventing the heart chambers from filling normally.
Thrombolytic Agents
Pharmacology
Thrombolytic Agents:
Tissue Plasminogen Activator (t-PA, Activase)
t-PA is a serine protease. It is a poor plasminogen activator in the absence of fibrin. t-PA binds to fibrin and activates bound plasminogen several hundred-fold more rapidly than it activates plasminogen in the circulation.
Streptokinase (Streptase)
Streptokinase is a protein produced by β-hemolytic streptococci. It has no intrinsic enzymatic activity, but forms a stable noncovalent 1:1 complex with plasminogen. This produces a conformational change that exposes the active site on plasminogen that cleaves a peptide bond on free plasminogen molecules to form free plasmin.
Urokinase (Abbokinase)
Urokinase is isolated from cultured human cells.Like streptokinase, it lacks fibrin specificity and therefore readily induces a systemic lytic state. Like t-PA, Urokinase is very expensive.
Contraindications to Thrombolytic Therapy:
• Surgery within 10 days, including organ biopsy, puncture of noncompressible vessels, serious trauma, cardiopulmonary resuscitation.
• Serious gastrointestinal bleeding within 3 months.
• History of hypertension (diastolic pressure >110 mm Hg).
• Active bleeding or hemorrhagic disorder.
• Previous cerebrovascular accident or active intracranial bleeding.
Aminocaproic acid:
Aminocaproic acid prevents the binding or plasminogen and plasmin to fibrin. It is a potent inhibitor for fibrinolysis and can reverse states that are associated with excessive fibrinolysis.
Graded Contractions and Muscle Metabolism
PhysiologyGraded Contractions and Muscle Metabolism
The muscle twitch is a single response to a single stimulus. Muscle twitches vary in length according to the type of muscle cells involved. .
Fast twitch muscles such as those which move the eyeball have twitches which reach maximum contraction in 3 to 5 ms (milliseconds). [superior eye] and [lateral eye] These muscles were mentioned earlier as also having small numbers of cells in their motor units for precise control.
The cells in slow twitch muscles like the postural muscles (e.g. back muscles, soleus) have twitches which reach maximum tension in 40 ms or so.
The muscles which exhibit most of our body movements have intermediate twitch lengths of 10 to 20 ms.
The latent period, the period of a few ms encompassing the chemical and physical events preceding actual contraction.
This is not the same as the absolute refractory period, the even briefer period when the sarcolemma is depolarized and cannot be stimulated. The relative refractory period occurs after this when the sarcolemma is briefly hyperpolarized and requires a greater than normal stimulus
Following the latent period is the contraction phase in which the shortening of the sarcomeres and cells occurs. Then comes the relaxation phase, a longer period because it is passive, the result of recoil due to the series elastic elements of the muscle.
We do not use the muscle twitch as part of our normal muscle responses. Instead we use graded contractions, contractions of whole muscles which can vary in terms of their strength and degree of contraction. In fact, even relaxed muscles are constantly being stimulated to produce muscle tone, the minimal graded contraction possible.
Muscles exhibit graded contractions in two ways:
1) Quantal Summation or Recruitment - this refers to increasing the number of cells contracting. This is done experimentally by increasing the voltage used to stimulate a muscle, thus reaching the thresholds of more and more cells. In the human body quantal summation is accomplished by the nervous system, stimulating increasing numbers of cells or motor units to increase the force of contraction.
2) Wave Summation ( frequency summation) and Tetanization- this results from stimulating a muscle cell before it has relaxed from a previous stimulus. This is possible because the contraction and relaxation phases are much longer than the refractory period. This causes the contractions to build on one another producing a wave pattern or, if the stimuli are high frequency, a sustained contraction called tetany or tetanus. (The term tetanus is also used for an illness caused by a bacterial toxin which causes contracture of the skeletal muscles.) This form of tetanus is perfectly normal and in fact is the way you maintain a sustained contraction.
Treppe is not a way muscles exhibit graded contractions. It is a warmup phenomenon in which when muscle cells are initially stimulated when cold, they will exhibit gradually increasing responses until they have warmed up. The phenomenon is due to the increasing efficiency of the ion gates as they are repeatedly stimulated. Treppe can be differentiated from quantal summation because the strength of stimulus remains the same in treppe, but increases in quantal summation
Length-Tension Relationship: Another way in which the tension of a muscle can vary is due to the length-tension relationship. This relationship expresses the characteristic that within about 10% the resting length of the muscle, the tension the muscle exerts is maximum. At lengths above or below this optimum length the tension decreases.
Coccidioidomycosis
General Pathology
Coccidioidomycosis (Valley Fever; San Joaquin Fever)
A disease caused by the fungus Coccidioides immitis, usually occurring in a primary form as an acute benign asymptomatic or self-limited respiratory infection, occasionally disseminating to cause focal lesions in skin, subcutaneous tissues, lymph nodes, bones, liver, kidneys, meninges, brain, or other tissues.
Primary coccidioidomycosis is usually asymptomatic, but nonspecific respiratory symptoms resembling influenza or acute bronchitis sometimes occur or, less often, acute pneumonia or pleural effusion. Symptoms, in decreasing order of frequency, include fever, cough, chest pain, chills, sputum production, sore throat, and hemoptysis.
Progressive disseminated coccidioidomycosis may develop a few weeks, months, or occasionally years after primary infections,, is more common in men than women and is more likely to occur in association with HIV infection, immunosuppressive therapy
Symptoms often are nonspecific, including low-grade fever, anorexia, weight loss, and weakness. Extensive pulmonary involvement may cause progressive cyanosis, dyspnea, and discharge of mucopurulent or bloody sputum. Extrapulmonary lesions are usually focal, involving one or more tissue sites in bones, joints, skin, subcutaneous tissues, viscera, brain, or meninges. Draining sinus tracts sometimes connect deeper lesions to the skin. Localized extrapulmonary lesions often become chronic and recur frequently, sometimes long after completion of seemingly successful antifungal therapy.