NEET MDS Synopsis
Comparison of Fatty acid synthesis and b-oxidation pathways
Biochemistry
b Oxidation Pathway
Fatty Acid Synthesis
pathway location
mitochondrial matrix
cytosol
acyl carriers (thiols)
Coenzyme-A
phosphopantetheine (ACP) & cysteine
electron acceptors/donor
FAD & NAD+
NADPH
hydroxyl intermediate
L
D
2-C product/donor
acetyl-CoA
malonyl-CoA (& acetyl-CoA)
AGE CHANGES of the Periodontal Ligament (PDL)
Dental Anatomy
AGE CHANGES
Progressive apical migration of the dentogingival junction.
Toothbrush abrasion of the area can expose dentin that can cause root caries and tooth mobility.
Histology of the alveolar bone
Near the end of the 2nd month of fetal life, mandible and maxilla form a groove that is opened toward the surface of the oral cavity.
As tooth germs start to develop, bony septa form gradually. The alveolar process starts developing strictly during tooth eruption.
The alveolar process is the bone that contains the sockets (alveoli) for the teeth and consists of
a) outer cortical plates
b) a central spongiosa and
c) bone lining the alveolus (bundle bone)
The alveolar crest is found 1.5-2.0 mm below the level of the CEJ.
If you draw a line connecting the CE junctions of adjacent teeth, this line should be parallel to the alveolar crest. If the line is not parallel, then there is high probability of periodontal disease.
Bundle Bone
The bundle bone provides attachment to the periodontal ligament fibers. It is perforated by many foramina that transmit nerves and vessels (cribiform plate). Embedded within the bone are the extrinsic fiber bundles of the PDL mineralized only at the periphery. Radiographically, the bundle bone is the lamina dura. The lining of the alveolus is fairly smooth in the young but rougher in the adults.
Clinical considerations
Resorption and regeneration of alveolar bone
This process can occur during orthodontic movement of teeth. Bone is resorbed on the side of pressure and opposed on the site of tension.
Osteoporosis
Osteoporosis of the alveolar process can be caused by inactivity of tooth that does not have an antagonist
MAXILLARY FIRST BICUSPID
Dental Anatomy
MAXILLARY FIRST BICUSPID (PREMOLARS)
It is considered to be the typical bicuspid. (The word "bicuspid" means "having two cusps.")
Facial: The buccal surface is quite rounded and this tooth resembles the maxillary canine. The buccal cusp is long; from that cusp tip, the prominent buccal ridge descends to the cervical line of the tooth.
Lingual: The lingual cusp is smaller and the tip of that cusp is shifted toward the mesial. The lingual surface is rounded in all aspects.
Proximal: The mesial aspect of this tooth has a distinctive concavity in the cervical third that extends onto the root. It is called variously the mesial developmental depression, mesial concavity, or the 'canine fossa'--a misleading description since it is on the premolar. The distal aspect of the maxillary first permanent molar also has a developmental depression. The mesial marginal developmental groove is a distinctive feature of this tooth.
Occlusal: There are two well-defined cusps buccal and lingual. The larger cusp is the buccal; its cusp tip is located midway mesiodistally. The lingual cusp tip is shifted mesially. The occlusal outline presents a hexagonal appearance. On the mesial marginal ridge is a distinctive feature, the mesial marginal developmental groove.
Contact Points;The distal contact area is located more buccal than is the mesial contact area.
Root Surface:-The root is quite flat on the mesial and distal surfaces. In about 50 percent of maxillary first bicuspids, the root is divided in the apical third, and when it so divided, the tips of the facial and lingual roots are slender and finely tapered.
Cells Of The Exudate
General Pathology
Cells Of The Exudate
Granulocytes (Neutrophils, eosinophils, and basophils)
Monocytes (and tissue macrophages)
Lymphocytes
Neutrophils (polymorphs).
Characteristics
(1) Cell of acute inflammation.
(2) Actively motile.
(3) Phagocytic.
(4) Respond to chemotactic agents like.
Complement products.
Bacterial products.
Tissue breakdown
Lysosomal enzymes of other polymorphs
Functions
(1) Phagocytosis and intracellular digestion of bacteria.
(2) Exocytosis of lysosomal enzymes to digest dead tissue as the first step in the process of repair.
Eosinophils
Characteristics
(I) Cell of allergjc and immunologic inflammation.
(2) Motile and phagocytic but less so than a neutrophil.
(3) Response to chemotaxis similar to neutrophil. In addition, it is also responsive to antigens and antigen-antibody complexes.
(4) Steroids cause depletion of eosinophils.
Functions
(1) Contain most of the lysosomal enzymes that polymorphs have
(2) control of Histamine release and degradation in inflammation
Basophils (and mast cells)
Characteristics
(1) Contain coarse metachromatic granules.
(2) Contain, histamine and proteolytic enzymes
Functions
Histamine: release which causes some of the changes of inflammation and allergic
reactions. .
Monocytes .
Blood monocytes form a component of. the mononuclear phagocytic system (MPS), the other being tissue macrophages The tissue macrophages may be :
(a) Fixed phagocytic. cells:
Kuffer cell of liver.
Sinusoidal lining cells of spleen and lymph nodes.
Pleural and peritoneal macrophages
Alveolar macrophages.
Microglial cells.
(b) Wandering macrophages or tissue histiocytes.
The tissue histiocytes are derived from blood monocytes.
Characteristics
.(1)Seen in inflammation of some duration, as they -outlive polymorphs.
(2) Actively phagocytic and motile.
(3) Fuse readily to from giant cells in certain situations.
Function
(1) Phagocytosis.
(2) Lysosomal enzyme secretion.
(3) Site of synthesis of some components of complement.
(4) Antigen handling and processing before presenting it to the Immune competent cell.
(5) Secretion of lysosyme and interferon.
Giant cells can be
(A) Physiological
Syncytiotrophoblast, megakatyocytes, striated muscle, osteoclast.
(B) Pathological:
Foreign body: in the presence of particulate foreign matter like talc, suture material etc. and in certain infections_e g fungal.
Langhan's type: a variant of foreign body giant cell seen in tuberculosis.
Touton type in lipid rich situations like Xanthomas, lipid granulomas etc.
(iv) Aschoff cell in rheumatic carditis.
(v) Tumour gjant cells e.g. Reid-Sternberg cell in Hodgkin's Lymphoma, giant cells in any malignancy.
Lymphocytes and Plasma cells
These are the small mononuclear cell comprising the immune system
They are less motile than_macrophages and neutrophils and are seen in chronic inflammation and immune based diseases.
Aminoglycoside
Pharmacology
Aminoglycoside
Aminoglycosides are a group of antibiotics that are effective against certain types of bacteria. They include amikacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, streptomycin, and tobramycin. Those which are derived from Streptomyces species
Aminoglycosides work by binding to the bacterial 30S ribosomal subunit, causing misreading of t-RNA, leaving the bacterium unable to synthesize proteins vital to its growth.
Aminoglycosides are useful primarily in infections involving aerobic, Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. Streptomycin was the first effective drug in the treatment of tuberculosis, though the role of aminoglycosides such as streptomycin and amikacin have been eclipsed (because of their toxicity and inconvenient route of administration) except for multiple drug resistant strains.
Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis.
Because of their potential for ototoxicity and renal toxicity, aminoglycosides are administered in doses based on body weight. Blood drug levels and creatinine are monitored during the course of therapy.
There is no oral form of these antibiotics: they are generally administered intravenously, though some are used in topical preparations used on wounds.
Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses.
Mandibular Tori
Oral and Maxillofacial SurgeryMandibular Tori
Mandibular tori are bony growths that occur on the mandible,
typically on the lingual aspect of the alveolar ridge. While they are often
asymptomatic, there are specific indications for their removal, particularly
when they interfere with oral function or prosthetic rehabilitation.
Indications for Removal
Interference with Denture Construction:
Mandibular tori may obstruct the proper fitting of full or partial
dentures, necessitating their removal to ensure adequate retention and
comfort.
Ulceration and Slow Healing:
If the mucosal covering over the torus ulcerates and the wound
exhibits extremely slow healing, surgical intervention may be required
to promote healing and prevent further complications.
Interference with Speech and Deglutition:
Large tori that impede normal speech or swallowing may warrant
removal to improve the patient's quality of life and functional
abilities.
Surgical Technique
Incision Placement:
The incision should be made on the crest of the ridge if
the patient is edentulous (without teeth). This approach allows for
better access to the torus while minimizing trauma to surrounding
tissues.
If there are teeth present in the area, the incision should be made
along the gingival margin. This helps to preserve the
integrity of the gingival tissue and maintain aesthetics.
Avoiding Direct Incision Over the Torus:
It is crucial not to make the incision directly over the torus.
Incising over the torus can lead to:
Status Line: Leaving a visible line on the
traumatized bone, which can affect aesthetics and function.
Thin Mucosa: The mucosa over the torus is
generally very thin, and an incision through it can result in
dehiscence (wound separation) and exposure of the underlying bone,
complicating healing.
Surgical Procedure:
After making the appropriate incision, the mucosal flap is elevated
to expose the underlying bone.
The torus is then carefully removed using appropriate surgical
instruments, ensuring minimal trauma to surrounding tissues.
Hemostasis is achieved, and the mucosal flap is repositioned and
sutured back into place.
Postoperative Care:
Patients may experience discomfort and swelling following the
procedure, which can be managed with analgesics.
Instructions for oral hygiene and dietary modifications may be
provided to promote healing and prevent complications.
Follow-Up:
Regular follow-up appointments are necessary to monitor healing and
assess for any potential complications, such as infection or delayed
healing.
Chemical Mediators In Inflammation
General Pathology
Chemical Mediators In Inflammation
Can be classified as :
A. Neurogenic
Also called the Triple Response of Lewis. It involves neurogenic vasodilatation of arterioles due to antidromic axon reflex arc. The constituents of the response are:
1. arteriolar vasoconstriction followed by
2. arteriolar vasodilatation
3. swelling
B. Chemical
1. Amines: Histamine and 5 hydroxytryptamine. Released from platelets and mast cells.
Actions: Immediate and short lived.
Dilatation of arterioles.
Increased capillary premeability.
Kinins: Bradykinin and kallidin These are present in inactive from and are activated by kinin forming proteases
Actions:
Arteriolar dilatation.
Increased vascular permeability
Pain
Kinin forming proteases Plasmin and Kallikrein. Present as inactive precursors.
Cleavage products of complement C3a und C5a are called anaphylatoxins
Actions:
Histamine release from mast cells
Chemotaxis (also C567 )
Enhance phagocytosis.
Polymorph components
Cationic: proteins which cause
Increased permeability
Histamine release.
Chemotaxis of monocytes
Neutral proteases which:
Cleave C3 and C5 to active form
Convert Kininogen to Kinin
Increase permeability.
Acid proteases which liberate leucokinins
Slow reacting. substance of anaphylaxis: (SRS-A) is a lipid released from mast cell.
Action --Increases vascular permeability
Prostaglandins: E1 + E2 .
Platelets are rich source
Action:
Platelets are a rich source.
Vasodilatation.
Increased permeability.
Pain.
VIII. Miscellaneous: like
Tissue lactic acid.
Bacterial toxins.
DISINFECTION AND STERILIZATION
General Microbiology
DISINFECTION AND STERILIZATION
• Sterilization is the best destruction or com removal_of all forms of micro organisms.
• Disinfection is the destruction of many microorganisms but usually the b spores.
• Antisepsis is the destruction or inhibition of microorganisms in living tissues thereby limiting or preventing the harmful effect of infection.
• Astatic Agent would only inhibit the growth of microorganisms (bacteriostatic, fungistatic, sporostatic).
• Acidal agent would kill the microorganism (bactericidal. virucidal, fungicidal)
• Sterilants are the chemicals which under controlled conditions can kill sporinQ bacteria.