NEET MDS Synopsis
Celecoxib
Pharmacology
Celecoxib
is a highly selective COX-2 inhibitor and primarily inhibits this isoform of cyclooxygenase, whereas traditional NSAIDs inhibit both COX-1 and COX-2. Celecoxib is approximately 10-20 times more selective for COX-2 inhibition over COX-1.
Being a sulphonamide can cause skin rash & hypersensitivity rxn., occasional oedema& HT.
Indication
Osteoarthritis ( 100‐200mg BID ) , rheumatoid arthritis, dysmenorrhea, acute gouty attacks, acute musculoskeletal pain.
Anchorage
OrthodonticsAnchorage in orthodontics refers to the resistance to unwanted tooth movement
during orthodontic treatment. It is a critical concept that helps orthodontists
achieve desired tooth movements while preventing adjacent teeth or the entire
dental arch from shifting. Proper anchorage is essential for effective treatment
planning and execution, especially in complex cases where multiple teeth need to
be moved simultaneously.
Types of Anchorage
Absolute Anchorage:
Definition: This type of anchorage prevents any
movement of the anchorage unit (the teeth or structures providing
support) during treatment.
Application: Used when significant movement of
other teeth is required, such as in cases of molar distalization or when
correcting severe malocclusions.
Methods:
Temporary Anchorage Devices (TADs): Small
screws or plates that are temporarily placed in the bone to provide
stable anchorage.
Extraoral Appliances: Devices like headgear
that anchor to the skull or neck to prevent movement of certain
teeth.
Relative Anchorage:
Definition: This type allows for some movement of
the anchorage unit while still providing enough resistance to achieve
the desired tooth movement.
Application: Commonly used in cases where some
teeth need to be moved while others serve as anchors.
Methods:
Brackets and Bands: Teeth can be used as
anchors, but they may move slightly during treatment.
Class II or Class III Elastics: These can be
used to create a force system that allows for some movement of the
anchorage unit.
Functional Anchorage:
Definition: This type utilizes the functional
relationships between teeth and the surrounding structures to achieve
desired movements.
Application: Often used in conjunction with
functional appliances that guide jaw growth and tooth positioning.
Methods:
Functional Appliances: Such as the Herbst or
Bionator, which reposition the mandible and influence the growth of
the maxilla.
Factors Influencing Anchorage
Tooth Position: The position and root morphology of the
anchorage teeth can affect their ability to resist movement.
Bone Quality: The density and health of the surrounding
bone can influence the effectiveness of anchorage.
Force Magnitude and Direction: The amount and direction
of forces applied during treatment can impact the stability of anchorage.
Patient Compliance: Adherence to wearing appliances as
prescribed is crucial for maintaining effective anchorage.
Clinical Considerations
Treatment Planning: Proper assessment of anchorage
needs is essential during the treatment planning phase. Orthodontists must
determine the type of anchorage required based on the specific movements
needed.
Monitoring Progress: Throughout treatment,
orthodontists should monitor the anchorage unit to ensure it remains stable
and that desired tooth movements are occurring as planned.
Adjustments: If unwanted movement of the anchorage unit
occurs, adjustments may be necessary, such as changing the force system or
utilizing additional anchorage methods.
CNS PROTECTION
Physiology
CNS PROTECTION
- Bones of the Skull Frontal, Temporal, Parietal, Sphenoid, Occipital
- Cranial Meninges Dura mater, Arachnoid Space, Pia mater
- Cerebrospinal Fluid
Secreted by Chroid Plexi in Ventricles
Circulation through ventricles and central canal
Lateral and Median apertures from the 4th ventricle into the subarachnoid space
Arachnoid villi of the superior sagittal sinus return CSF to the venous circulation
Hydrocephalic Condition, blockage of the mesencephalic aqueduct, backup of CSF, Insertion of a shunt to drain the excess CSF
Other Antidepressants
Pharmacology
Serotonin-norepinephrine reuptake inhibitors(SNRIs)
e.g. venlafaxine and duloxetine
- Inhibit the reuptake of both 5-HT and norepinephrine
- Has a more favourable adverse effect profile than TCAs
Norepinephrine reuptake inhibitor
e.g. bupropion, reboxetine
Monoamine receptor antagonists
e.g. mirtazapine, trazodone, mianserin
Piezosurgery
Oral and Maxillofacial SurgeryPiezosurgery
Piezosurgery is an advanced surgical technique that utilizes
ultrasonic vibrations to cut bone and other hard tissues with precision. This
method has gained popularity in oral and maxillofacial surgery due to its
ability to minimize trauma to surrounding soft tissues, enhance surgical
accuracy, and improve patient outcomes. Below is a detailed overview of the
principles, advantages, applications, and specific uses of piezosurgery in oral
surgery.
Principles of Piezosurgery
Ultrasonic Technology: Piezosurgery employs ultrasonic
waves to create high-frequency vibrations in specially designed surgical
tips. These vibrations allow for precise cutting of bone while preserving
adjacent soft tissues.
Selective Cutting: The ultrasonic frequency is tuned to
selectively cut mineralized tissues (like bone) without affecting softer
tissues (like nerves and blood vessels). This selectivity reduces the risk
of complications and enhances healing.
Advantages of Piezosurgery
Strength and Durability of Tips:
Piezosurgery tips are made from high-quality materials that are
strong and resistant to fracture. This durability allows for extended
use without the need for frequent replacements, making them
cost-effective in the long run.
Access to Difficult Areas:
The design of piezosurgery tips allows them to reach challenging
anatomical areas that may be difficult to access with traditional
surgical instruments. This is particularly beneficial in complex
procedures involving the mandible and maxilla.
Minimized Trauma:
The ultrasonic cutting action produces less heat and vibration
compared to traditional rotary instruments, which helps to preserve the
integrity of surrounding soft tissues and reduces postoperative pain and
swelling.
Enhanced Precision:
The ability to perform precise cuts allows for better control during
surgical procedures, leading to improved outcomes and reduced
complications.
Reduced Blood Loss:
The selective cutting action minimizes damage to blood vessels,
resulting in less bleeding during surgery.
Applications in Oral Surgery
Piezosurgery has a variety of applications in oral and maxillofacial surgery,
including:
Osteotomies:
LeFort I Osteotomy: Piezosurgery is particularly
useful in performing pterygoid disjunction during LeFort I osteotomy.
The ability to precisely cut bone in the pterygoid region allows for
better access and alignment during maxillary repositioning.
Intraoral Vertical Ramus Osteotomy (IVRO): The
lower border cut at the lateral surface of the ramus can be performed
with piezosurgery, allowing for precise osteotomy while minimizing
trauma to surrounding structures.
Inferior Alveolar Nerve Lateralization:
Piezosurgery can be used to carefully lateralize the inferior alveolar
nerve during procedures such as bone grafting or implant placement,
reducing the risk of nerve injury.
Bone Grafting:
Piezosurgery is effective in harvesting bone grafts from donor
sites, as it allows for precise cuts and minimal damage to surrounding
tissues. This is particularly important in procedures requiring
autogenous bone grafts.
Implant Placement:
The technique can be used to prepare the bone for dental implants,
allowing for precise osteotomy and reducing the risk of complications
associated with traditional drilling methods.
Sinus Lift Procedures:
Piezosurgery is beneficial in sinus lift procedures, where precise
bone cutting is required to elevate the sinus membrane without damaging
it.
Tumor Resection:
The precision of piezosurgery makes it suitable for resecting tumors
in the jaw while preserving surrounding healthy tissue.
Mefenamic acid
Pharmacology
Mefenamic acid
Analgesic, anti‐inflammatory properties less effective than aspirin
Short half‐lives, should not be used for longer than one week and never in pregnancy and in children.
Enhances oral anticoagulants
Used to treat pain, including menstrual pain. It decreases inflammation (swelling) and uterine contractions.
Aplasticanaemia and pancytopenia
General Pathology
Aplasticanaemia and pancytopenia.
Aplastic anaemia is a reduction in all the formed elements of blood due to marrow hypoplasia.
Causes
- Primary or Idiopathic.
- Secondary to :
1 Drugs :
Antimetabolites and antimitotic agents.
Antiepileptics.
Phenylbutazone.
Chloramphenicol.
2 Industrial chemicals.
Benzene.
DDT and other insecticides.
TNT (used in explosives).
3 Ionising radiation
- Familial aplasia
Pancytopenia (or reduction in the formed elements of blood) can be caused by other conditions also like:
-Subleukaemic acute leukaemia.
-Megaloblastic anaemia
-S.L.E.
-hypersplenism.
-Marrow infiltration by lymphomas metastatic deposits, tuberculosis, myeloma etc
Features:
- Anaemia.
- Leucopenia upper respiratory infections.
- Thrombocytopenis :- petechiae and bruising.
Blood picture:
- Normocytic normochromic anaemia with minimal anisopoikilocytosis in aplastic anaemia. Other causes of pancytopenia may show varying degrees of anisopoikilocytosis
- Neutropenia with hypergranulation and high alkaline phosphatase.
- Low platelet counts
Bone marrow:
- Hypoplastic (may have patches of norm cellular or hyper cellular marrow) which may -> dry tap. .
- Increase in fat cells , fibroblasts , reticulum cells, lymphocytes and plasma cells
- Decrease in precursors of all three-Series.
- Underlying cause if any, of pancytopenia may be seen
Reaction of Acrylic Resins
Dental Materials
Reaction
PMMA powder makes mixture viscous for manipulation before curing. Chemical accelerators cause decomposition of benzoyl peroxide into free radicals that initiate polymerization of monomer
New PMMA is formed into a matrix that surrounds PMMA powder. Linear shrinkage of 5% to 7% during setting. but dimensions of appliances are not critical