NEET MDS Shorts
33756
Dental Materials
Sodium chloride is an accelerator up to about 2% of the hemihydrates, but at a higher concentration, it acts as a retarder. Sodium sulphate has its maximum acceleration effect at approximately 3.4%; at greater concentrations, it becomes a retarder. Citrates. acetates and borates generally retard the reaction.
The most commonly used accelerator is potassium sulphate. It is particularly effective in concentrations higher than 2% since the reaction product. which seems to be syngenite (K,Ca[SO4].H1O) crystallizes rapidly. Many soluble sulphates act as accelerators, whereas powdered gypsum (calcium sulphate dehydrate) accelerates the setting rate, because the
particles act as nuclei of crystallization.
30682
ProsthodonticsLateral throat form occupied by retromylohyoid flange in lower denture should be large, one-half inch.
66235
General PathologyDiverticulitis is characterized by left lower quadrant pain, fever, and leukocytosis, especially in elderly patients.
97626
Orthodontics
SOLUTION If heavy pressure is applied to a tooth, pain develops almost immediately as the PDL is literally crushed. If appropriate orthodontic force is applied, the patient feels little or nothing immediately. Several hours later, however, pain usually appears. The patient feels a mild aching sensation, and the teeth are quite sensitive to pressure, so that biting a hard object hurts. The pain typically lasts for 2 to 4 days, and then disappears until the orthodontic appliance is reactivated. At that point, a similar cycle may recur, but for almost all patients, the pain associated with the initial activation of the appliance is the most severe.
There is no excuse for using force levels for orthodontic tooth movement that produce immediate pain of this type.
10327
RadiologyZonography is a type of panoramography.
10061
Oral PathologyChronic sinusitis is the most common extraoral cause of halitosis. Infected sinuses produce purulent discharge that drains into the oral cavity, causing bad breath. While diabetes, alcohol, and indigestion can cause halitosis, chronic sinusitis is more prevalent.
59933
Oral Surgery
Local anaesthetics act by blocking voltage‑gated sodium
channels, preventing depolarization and conduction of nerve impulses.
The sensitivity of different nerve fibres depends on their diameter,
myelination, and conduction velocity. Type B fibres Small, myelinated preganglionic autonomic fibres. Moderately sensitive to local anaesthetics. Type C fibres Smallest, unmyelinated fibres. Carry dull, aching pain and temperature sensations. Most sensitive to local anaesthetics because
of their small diameter and lack of myelin. Type A‑delta fibres Small, thinly myelinated fibres. Carry sharp, pricking pain. Less sensitive than Type C fibres but more sensitive than
larger A‑alpha fibres. Fibres supplying muscle spindles (Type A‑alpha fibres) Large, heavily myelinated fibres. Conduct proprioception and motor signals. Least sensitive to local anaesthetics due to
their large diameter and thick myelin sheath. Local anaesthetics preferentially block small,
unmyelinated fibres first (Type C), followed by small myelinated fibres
(Type B, A‑delta). Large myelinated fibres (A‑alpha) are blocked last. This
explains why pain sensation is lost before motor function during local
anaesthesia.
72066
RadiologyThe base of the skull can be viewed by both Towne's projection and Submentovertex.
90257
Dental Materials
86589
RadiologyThe reflecting layer used in intensifying screens is titanium oxide & magnesium carbonate.