NEET MDS Synopsis
Diphenoxylate
Pharmacology
Diphenoxylate (present in Lomotil)
A meperidine congener
Not absorbed very well at recommended doses.
Very useful in the treatment of diarrhea.
Nutrition and tooth development
Dental Anatomy
Nutrition and tooth development
As in other aspects of human growth and development, nutrition has an effect on the developing tooth. Essential nutrients for a healthy tooth include calcium, phosphorus, fluoride, and vitamins A, C, and D. Calcium and phosphorus are needed to properly form the hydroxyapatite crystals, and their levels in the blood are maintained by Vitamin D. Vitamin A is necessary for the formation of keratin, as Vitamin C is for collagen. Fluoride is incorporated into the hydroxyapatite crystal of a developing tooth and makes it more resistant to demineralization and subsequent decay.
Deficiencies of these nutrients can have a wide range of effects on tooth development. In situations where calcium, phosphorus, and vitamin D are deficient, the hard structures of a tooth may be less mineralized. A lack of vitamin A can cause a reduction in the amount of enamel formation. Fluoride deficency causes increased demineralization when the tooth is exposed to an acidic environment, and also delays remineralization. Furthermore, an excess of fluoride while a tooth is in development can lead to a condition known as fluorosis.
Nitrous Oxide
Pharmacology
Nitrous Oxide (N2O)
MAC 100%, blood/gas solubility ratio 0.47
- An inorganic gas., low solubility in blood, but greater solubility than N2
- Inflammable, but does support combustion.
- Excreted primarily unchanged through the lungs.
- It provides amnesia and analgesia when administered alone.
- Does not produce muscular relaxation.
- Less depressant to both the cardiovascular system and respiratory system than most of the other inhalational anesthetics.
- Lack of potency and tendency to produce anoxia are its primary limitations.
- The major benefit of nitrous oxide is its ability to reduce the amount of the secondary anesthetic agent that is necessary to reach a specified level of anesthesia.
Anterior Crossbite
OrthodonticsAnterior Crossbite
Anterior crossbite is a dental condition where one or more
of the upper front teeth (maxillary incisors) are positioned behind the lower
front teeth (mandibular incisors) when the jaws are closed. This misalignment
can lead to functional issues, aesthetic concerns, and potential wear on the
teeth. Correcting anterior crossbite is essential for achieving proper occlusion
and improving overall dental health.
Methods to Correct Anterior Crossbite
Acrylic Incline Plane:
Description: An acrylic incline plane is a
removable appliance that can be used to guide the movement of the teeth.
It is designed to create a ramp-like surface that encourages the
maxillary incisors to move forward.
Mechanism: The incline plane helps to reposition
the maxillary teeth by providing a surface that directs the teeth into a
more favorable position during function.
Reverse Stainless Steel Crown:
Description: A reverse stainless steel crown can be
used in cases where the anterior teeth are significantly misaligned.
This crown is designed to provide a stable and durable solution for
correcting the crossbite.
Mechanism: The crown can be adjusted to help
reposition the maxillary teeth, allowing them to move into a more normal
relationship with the mandibular teeth.
Hawley Retainer with Recurve Springs:
Description: A Hawley retainer is a removable
orthodontic appliance that can be modified with recurve springs to
correct anterior crossbite.
Mechanism: The recurve springs apply gentle
pressure to the maxillary incisors, tipping them forward into a more
favorable position relative to the mandibular teeth. This appliance is
comfortable, easily retained, and predictable in its effects.
Fixed Labial-Lingual Appliance:
Description: A fixed labial-lingual appliance is a
type of orthodontic device that is bonded to the teeth and can be used
to correct crossbites.
Mechanism: This appliance works by applying
continuous forces to the maxillary teeth, tipping them forward and
correcting the crossbite. It may include a vertical removable arch for
ease of adjustment and recurve springs to facilitate movement.
Vertical Removable Arch:
Description: This appliance can be used in
conjunction with other devices to provide additional support and
adjustment capabilities.
Mechanism: The vertical removable arch allows for
easy modifications and adjustments, helping to jump the crossbite by
repositioning the maxillary teeth.
SPECIAL VISCERAL AFFERENT (SVA) PATHWAYS
Physiology
SPECIAL VISCERAL AFFERENT (SVA) PATHWAYS
Taste
Special visceral afferent (SVA) fibers of cranial nerves VII, IX, and X conduct signals into the solitary tract of the brainstem, ultimately terminating in the nucleus of the solitary tract on the ipsilateral side.
Second-order neurons cross over and ascend through the brainstem in the medial lemniscus to the VPM of the thalamus.
Thalamic projections to area 43 (the primary taste area) of the postcentral gyrus complete the relay.
SVA VII fibers conduct from the chemoreceptors of taste buds on the anterior twothirds of the tongue, while SVA IX fibers conduct taste information from buds on the posterior one-third of the tongue.
SVA X fibers conduct taste signals from those taste cells located throughout the fauces.
Smell
The smell-sensitive cells (olfactory cells) of the olfactory epithelium project their central processes through the cribiform plate of the ethmoid bone, where they synapse with mitral cells. The central processes of the mitral cells pass from the olfactory bulb through the olfactory tract, which divides into a medial and lateral portion The lateral olfactory tract terminates in the prepyriform cortex and parts of the amygdala of the temporal lobe.
These areas represent the primary olfactory cortex. Fibers then project from here to area 28, the secondary olfactory area, for sensory evaluation. The medial olfactory tract projects to the anterior perforated substance, the septum pellucidum, the subcallosal area, and even the contralateral olfactory tract.
Both the medial and lateral olfactory tracts contribute to the visceral reflex pathways, causing the viscerosomatic and viscerovisceral responses.
Digital Radiology
Radiology
Digital Radiology
Advances in computer and X-ray technology now permit the use of systems that employ sensors in place of X-ray ?lms (with emulsion). The image is either directly or indirectly converted into a digital representation that is displayed on a computer screen.
DIGITAL IMAGE RECEPTORS
- charged coupled device (CCD) used
- Pure silicon divided into pixels.
- Electromagnetic energy from visible light or X-rays interacts with pixels to create an electric charge that can be stored.
- Stored charges are transmitted electronically and create an analog output signal and displayed via digital converter (analog to digital converter).
ADVANTAGES OF DIGITAL TECHNIQUE
Immediate display of images.
Enhancement of image (e.g., contrast, gray scale, brightness).
Radiation dose reduction up to 60%.
Major disadvantage: High initial cost of sensors. Decreased image resolution and contrast as compared to D speed ?lms.
DIRECT IMAGING
- CCD or complementary metal oxide semiconductor (CMOS) detector used that is sensitive to electromagnetic radiation.
- Performance is comparable to ?lm radiography for detection of periodontal lesions and proximal caries in noncavitated teeth.
INDIRECT IMAGING
- Radiographic ?lm is used as the image receiver (detector).
- Image is digitized from signals created by a video device or scanner that views the radiograph.
Sensors
STORAGE PHOSPHOR IMAGING SYSTEMS
Phosphor screens are exposed to ionizing radiation which excites BaFBR:EU+2 crystals in the screen storing the image.
A computer-assisted laser then promotes the release of energy from the crystals in the form of blue light.
The blue light is scanned and the image is reconstructed digitally.
ELECTRONIC SENSOR SYSTEMS
X-rays are converted into light which is then read by an electronic sensor such as a CCD or CMOS.
Other systems convert the electromagnetic radiation directly into electrical impulses.
Digital image is created out of the electrical impulses.
Periodontium
Dental Anatomy
The periodontium consists of tissues supporting and investing the tooth and includes cementum, the periodontal ligament (PDL), and alveolar bone.
Parts of the gingiva adjacent to the tooth also give minor support, although the gingiva is Not considered to be part of the periodontium in many texts. For our purposes here, the groups Of gingival fibers related to tooth investment are discussed in this section.
Drugs used in Parasitology Treatment
Pharmacology
Amphotericin B: Naegleria fowleri, Leishmania donovani
Metronidazole: Giardia lamblia, Trichomona vaginalis, Entamoeba hystolytica
Nitazoxanide: Cryptosporidium
Bendazoles or Pyrantel Pamoate: Enterobius vermicularis, Ascaris lumbricoides, Ancylostoma duodenale, Necator americanus (ne M atodes)
Mebendazole: Toxocara canis
Albendazole: Strongyloides stercolaris, Toxocara canis, neurocysticercosis, Echinococcus granulosus.
Paziquantel: Taenia solium, Schistosoma, Diphylobotrium latum, Clonorchis (P latyhelminthes)
Pyrimethamine + Sulfadiazine: Toxoplasma gondii
Suramin: Trypanosma bruceii (blood borne)
Melarsoprol: Trypanosoma bruceii (CNS)
Nifurtimox or Benznidazole: Trypanosoma cruzi
Quinidine (IV): severe Plasmodium infx
Mefloquine or Atovaquone/Proguanil: Plasmodium resistant
Atovaquone + Azythromycin: Babesia
Diethylcarbamazine (DEC): Loa loa, Wucheria bancrofti
Ivermectin: Onchocerca volvulus, Strongyloides stercolaris
Sodium stibogluconate (Pentavalent Antimony): Leishmania donovani
Cloroquine: Plasmodium falciparum, Plasmodium malariae
Cloroquine + Primaquine: Plasmodium ovale, Plasmodium vivax