NEET MDS Lessons
Oral and Maxillofacial Surgery
- Minimum platelet count for surgery: 75,000/cu mm
- Absolute contraindication: Platelets < 50,000/cu mm
- Blood unit volume: 450 mL
- PRBC effect: ↑ Hb by 1 g/dL, ↑ Hct by 3%
- Warfarin patient: Check INR & PT before extraction
- Normal PT: 11–14 seconds
Postoperative Airway Obstruction
Causes
- Hematoma: Expanding neck hematoma
- Edema: Laryngeal or facial swelling
- Vocal cord paralysis: Recurrent laryngeal nerve injury
- Foreign body: Gauze, blood clots
Management
- Assessment: Rapid evaluation of obstruction level
- Position: Sitting up if conscious, stable
- Suction: Remove blood/debris if visible
- Medications: Steroids for edema, epinephrine for anaphylaxis
- Definitive: Secure airway if conservative measures fail
Anaphylaxis
Recognition
- Rapid onset: Minutes after exposure
- Skin: Urticaria, angioedema
- Respiratory: Bronchospasm, laryngeal edema
- Cardiovascular: Hypotension, tachycardia
Treatment
- Epinephrine: 0.3-0.5mg IM (1:1000)
- Airway: May need emergency surgical airway
- Fluids: Aggressive IV resuscitation
- Antihistamines: H1 and H2 blockers
- Steroids: Prevent biphasic reaction
Laryngospasm
Triggers
- Stimulation: Light anesthesia, secretions
- Irritants: Blood, gastric contents
- Medications: Propofol, succinylcholine
Treatment
- Positive pressure: Gentle bag-mask ventilation
- Larson's maneuver: Pressure at laryngospasm notch
- Succinylcholine: 0.25-0.5 mg/kg if severe
- Intubation: May be necessary if persistent
| Instrument | Use |
|---|---|
| Moons probe | Elevate mucoperiosteum |
| Hemostatic forceps | Control small vessel bleeding |
| Mouth props | Keep mouth open (metal/rubber) |
| Mouth gags | Used under GA (Doyen’s, Fergusson’s) |
| Heister’s jaw stretcher | For trismus |
| Curettes (Lucas) | Remove debris, cysts, tumors |
| Lister’s sinus forceps | Open abscess (Hilton’s method) |
| Rongeur forceps | Remove bone |
| Chisels | Unibeveled; bone removal |
Hockey Stick or London Hospital Elevator
The Hockey Stick Elevator, also known as the London Hospital Elevator, is a dental instrument used primarily in oral surgery and tooth extraction procedures. It is designed to facilitate the removal of tooth roots and other dental structures.
Design and Features
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Blade Shape: The Hockey Stick Elevator features a straight blade that is angled relative to the shank, similar to the Cryer’s elevator. However, unlike the Cryer’s elevator, which has a triangular blade, the Hockey Stick Elevator has a straight blade with a convex surface on one side and a flat surface on the other.
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Working Surface:
- The flat surface of the blade is the working surface and is equipped with transverse serrations. These serrations enhance the instrument's grip and contact with the root stump, allowing for more effective leverage during extraction.
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Appearance: The instrument resembles a hockey stick, which is how it derives its name. The distinctive shape aids in its identification and use in clinical settings.
Principles of Operation
- Lever and Wedge Principle:
- The Hockey Stick Elevator operates on the same principles as the Cryer’s elevator, utilizing the lever and wedge principle. This means that the instrument can be used to apply force to the tooth or root, effectively loosening it from the surrounding bone and periodontal ligament.
- Functionality:
- The primary function of the Hockey Stick Elevator is to elevate and luxate teeth or root fragments during extraction procedures. It can be particularly useful in cases where the tooth is impacted or has a curved root.
Cryosurgery
Cryosurgery is a medical technique that utilizes extreme rapid cooling to freeze and destroy tissues. This method is particularly effective for treating various conditions, including malignancies, vascular tumors, and aggressive tumors such as ameloblastoma. The process involves applying very low temperatures to induce localized tissue destruction while minimizing damage to surrounding healthy tissues.
Mechanism of Action
The effects of rapid freezing on tissues include:
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Reduction of Intracellular Water:
- Rapid cooling causes water within the cells to freeze, leading to a decrease in intracellular water content.
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Cellular and Cell Membrane Shrinkage:
- The freezing process results in the shrinkage of cells and their membranes, contributing to cellular damage.
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Increased Concentrations of Intracellular Solutes:
- As water is removed from the cells, the concentration of solutes (such as proteins and electrolytes) increases, which can disrupt cellular function.
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Formation of Ice Crystals:
- Both intracellular and extracellular ice crystals form during the freezing process. The formation of these crystals can puncture cell membranes and disrupt cellular integrity, leading to cell death.
Cryosurgery Apparatus
The equipment used in cryosurgery typically includes:
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Storage Bottles for Pressurized Liquid Gases:
- Liquid Nitrogen: Provides extremely low temperatures of approximately -196°C, making it highly effective for cryosurgery.
- Liquid Carbon Dioxide or Nitrous Oxide: These gases provide temperatures ranging from -20°C to -90°C, which can also be used for various applications.
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Pressure and Temperature Gauge:
- This gauge is essential for monitoring the pressure and temperature of the cryogenic gases to ensure safe and effective application.
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Probe with Tubing:
- A specialized probe is used to direct the pressurized gas to the targeted tissues, allowing for precise application of the freezing effect.
Treatment Parameters
- Time and Temperature: The specific time and temperature used during cryosurgery depend on the depth and extent of the tumor being treated. The clinician must carefully assess these factors to achieve optimal results while minimizing damage to surrounding healthy tissues.
Applications
Cryosurgery is applied in the treatment of various conditions, including:
- Malignancies: Used to destroy cancerous tissues in various organs.
- Vascular Tumors: Effective in treating tumors that have a significant blood supply.
- Aggressive Tumors: Such as ameloblastoma, where rapid and effective tissue destruction is necessary.
- Normal clotting time: 8 – 15 minutes.
- Platelet – rich plasma (1 unit): Raises platelet count by 7,000 – 10,000/μL.
- Fresh frozen plasma (150 mL): Contains 200 μ factors VIII & IX, 400 mg fibrinogen.
- Cryoprecipitate: Contains factors VIII, XIII, vWF, fibrinogen.
- DIC marker: Elevated D – dimers.
- Hemophilia factor levels: Majority have < 5%.
- Surgery in hemophilia: Raise factor levels to 50 – 75%.
Dry Socket (Alveolar Osteitis)
Dry socket, also known as alveolar osteitis, is a common complication that can occur after tooth extraction, particularly after the removal of mandibular molars. It is characterized by delayed postoperative pain due to the loss of the blood clot that normally forms in the extraction socket.
Key Features
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Pathophysiology:
- After a tooth extraction, a blood clot forms in the socket, which is essential for healing. In dry socket, this clot is either dislodged or dissolves prematurely, exposing the underlying bone and nerve endings.
- The initial appearance of the clot may be dirty gray, and as it disintegrates, the socket may appear gray or grayish-yellow, indicating the presence of bare bone without granulation tissue.
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Symptoms:
- Symptoms of dry socket typically begin 3 to 5 days after
the extraction. Patients may experience:
- Severe pain in the extraction site that can radiate to the ear, eye, or neck.
- A foul taste or odor in the mouth due to necrotic tissue.
- Visible empty socket with exposed bone.
- Symptoms of dry socket typically begin 3 to 5 days after
the extraction. Patients may experience:
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Local Therapy:
- Management of dry socket involves local treatment to alleviate pain
and promote healing:
- Irrigation: The socket is irrigated with a warm sterile isotonic saline solution or a dilute solution of hydrogen peroxide to remove necrotic material and debris.
- Application of Medications: After irrigation, an obtundent (pain-relieving) agent or a topical anesthetic may be applied to the socket to provide symptomatic relief.
- Management of dry socket involves local treatment to alleviate pain
and promote healing:
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Prevention:
- To reduce the risk of developing dry socket, patients are often
advised to:
- Avoid smoking and using straws for a few days post-extraction, as these can dislodge the clot.
- Follow postoperative care instructions provided by the dentist or oral surgeon.
- To reduce the risk of developing dry socket, patients are often
advised to: