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Oral and Maxillofacial Surgery - NEETMDS- courses
Oral and Maxillofacial Surgery

  • Snoring: Partial airway obstruction
  • Apnea: No airflow > 10 seconds
  • Hypopnea: > 2/3 decrease in tidal volume
  • Apnea – Hypopnea Index (AHI):
    [ \text{AHI} = \frac{\text{Apneas + Hypopneas}}{\text{Total sleep time}} \times 60 ]
  • UPPP surgery: Enlarges airway in anterosuperior & lateral directions
  • Passavant’s ridge: Superior pharyngeal constrictor contraction

  • Pediatric mandibular fractures: Greenstick, esp. condyle
  • TMJ ankylosis signs in child:
    • Limited mouth opening
    • Prominent antegonial notch
    • Elongated coronoid
    • Short ramus
    • Bony bridging
    • Fullness on affected side

Sutures

Sutures are an essential component of oral surgery, used to close wounds, secure grafts, and stabilize tissues after surgical procedures. The choice of suture material and sterilization methods is critical for ensuring effective healing and minimizing complications. Below is a detailed overview of suture materials, specifically focusing on catgut and its sterilization methods.

Types of Suture Materials

  1. Absorbable Sutures: These sutures are designed to be broken down and absorbed by the body over time. They are commonly used in oral surgery for soft tissue closure where long-term support is not necessary.

    • Catgut: A natural absorbable suture made from the intestinal mucosa of sheep or cattle. It is widely used in oral surgery due to its good handling properties and ability to promote healing.
  2. Non-Absorbable Sutures: These sutures remain in the body until they are removed or until they eventually break down. They are used in situations where long-term support is needed.

Catgut Sutures

Sterilization Methods: Catgut sutures must be properly sterilized to prevent infection and ensure safety during surgical procedures. Two common sterilization methods for catgut are:

  1. Gamma Radiation Sterilization:

    • Process: Catgut sutures are sterilized using gamma radiation, typically at a dose of 2.5 mega-rads. This method effectively kills bacteria and other pathogens without compromising the integrity of the suture material.
    • Preservation: After sterilization, catgut sutures are preserved in a solution of 2.5 percent formaldehyde and denatured absolute alcohol. This solution helps maintain the sterility of the sutures while preventing degradation.
    • Packaging: The sutures are stored in spools or foils to protect them from contamination until they are ready for use.
  2. Chromic Acid Method:

    • Process: In this method, catgut sutures are immersed in a solution containing 20 percent chromic acid and five parts of 8.5 percent glycerin. This process not only sterilizes the sutures but also enhances their durability.
    • Benefits: The chromic acid treatment helps to secure a longer stay in the pack, meaning that the sutures can maintain their strength and integrity for a more extended period before being used. This is particularly beneficial in surgical settings where sutures may need to be stored for some time.

Characteristics of Catgut Sutures

  • Absorbability: Catgut sutures are absorbable, typically losing their tensile strength within 7 to 14 days, depending on the type (plain or chromic).
  • Tensile Strength: They provide good initial tensile strength, making them suitable for various surgical applications.
  • Biocompatibility: Being a natural product, catgut is generally well-tolerated by the body, although some patients may have sensitivities or allergic reactions.
  • Handling: Catgut sutures are easy to handle and tie, making them a popular choice among surgeons.

Applications in Oral Surgery

  • Soft Tissue Closure: Catgut sutures are commonly used for closing incisions in soft tissues of the oral cavity, such as after tooth extractions, periodontal surgeries, and mucosal repairs.
  • Graft Stabilization: They can also be used to secure grafts in procedures like guided bone regeneration or soft tissue grafting.

Hemostatic Agents

Hemostatic agents are critical in surgical procedures to control bleeding and promote wound healing. Various materials are used, each with unique properties and mechanisms of action. Below is a detailed overview of some commonly used hemostatic agents, including Gelfoam, Oxycel, Surgical (Oxycellulose), and Fibrin Glue.

1. Gelfoam

  • Composition: Gelfoam is made from gelatin and has a sponge-like structure.

  • Mechanism of Action:

    • Gelfoam does not have intrinsic hemostatic properties; its hemostatic effect is primarily due to its large surface area, which comes into contact with blood.
    • When Gelfoam absorbs blood, it swells and exerts pressure on the bleeding site, providing a scaffold for the formation of a fibrin network.
  • Application:

    • Gelfoam should be moistened in saline or thrombin solution before application to ensure optimal performance. It is essential to remove all air from the interstices to maximize its effectiveness.
  • Absorption: Gelfoam is absorbed by the body through phagocytosis, typically within a few weeks.

2. Oxycel

  • Composition: Oxycel is made from oxidized cellulose.

  • Mechanism of Action:

    • Upon application, Oxycel releases cellulosic acid, which has a strong affinity for hemoglobin, leading to the formation of an artificial clot.
    • The acid produced during the wetting process can inactivate thrombin and other hemostatic agents, which is why Oxycel should be applied dry.
  • Limitations:

    • The acid produced can inhibit epithelialization, making Oxycel unsuitable for use over epithelial surfaces.

3. Surgical (Oxycellulose)

  • Composition: Surgical is a glucose polymer-based sterile knitted fabric created through the controlled oxidation of regenerated cellulose.

  • Mechanism of Action:

    • The local hemostatic mechanism relies on the binding of hemoglobin to oxycellulose, allowing the dressing to expand into a gelatinous mass. This mass acts as a scaffold for clot formation and stabilization.
  • Application:

    • Surgical can be applied dry or soaked in thrombin solution, providing flexibility in its use.
  • Absorption: It is removed by liquefaction and phagocytosis over a period of one week to one month. Unlike Oxycel, Surgical does not inhibit epithelialization and can be used over epithelial surfaces.

4. Fibrin Glue

  • Composition: Fibrin glue is a biological adhesive that contains thrombin, fibrinogen, factor XIII, and aprotinin.

  • Mechanism of Action:

    • Thrombin converts fibrinogen into an unstable fibrin clot, while factor XIII stabilizes the clot. Aprotinin prevents the degradation of the clot.
    • During wound healing, fibroblasts migrate through the fibrin meshwork, forming a more permanent framework composed of collagen fibers.
  • Applications:

    • Fibrin glue is used in various surgical procedures to promote hemostasis and facilitate tissue adhesion. It is particularly useful in areas where traditional sutures may be challenging to apply.

Pterygomandibular Space is an important anatomical area in the head and neck region, particularly relevant in dental and maxillofacial surgery. Understanding its boundaries, contents, and clinical significance is crucial for procedures such as local anesthesia, surgical interventions, and the management of infections. Here’s a detailed overview of the pterygomandibular space:

Boundaries of the Pterygomandibular Space

  1. Laterally:

    • Medial Surface of the Ramus of the Mandible: This boundary is formed by the inner aspect of the ramus, which provides a lateral limit to the space.
  2. Medially:

    • Lateral Surface of the Medial Pterygoid Muscle: The medial boundary is defined by the lateral aspect of the medial pterygoid muscle, which is a key muscle involved in mastication.
  3. Posteriorly:

    • Deep Portion of the Parotid Gland: The posterior limit of the pterygomandibular space is formed by the deep part of the parotid gland, which is significant in terms of potential spread of infections.
  4. Anteriorly:

    • Pterygomandibular Raphe: This fibrous band connects the pterygoid muscles and serves as the anterior boundary of the space.
  5. Roof:

    • Lateral Pterygoid Muscle: The roof of the pterygomandibular space is formed by the lateral pterygoid muscle. The space just below this muscle communicates with the pharyngeal spaces, which is clinically relevant for the spread of infections.

Contents of the Pterygomandibular Space

The pterygomandibular space contains several important structures:

  1. Nerves:

    • Lingual Nerve: This nerve provides sensory innervation to the anterior two-thirds of the tongue and is closely associated with the inferior alveolar nerve.
    • Mandibular Nerve (V3): The third division of the trigeminal nerve, which supplies sensory and motor innervation to the lower jaw and associated structures.
  2. Vessels:

    • Inferior Alveolar Artery: A branch of the maxillary artery that supplies blood to the lower teeth and surrounding tissues.
    • Mylohyoid Nerve and Vessels: The mylohyoid nerve, a branch of the inferior alveolar nerve, innervates the mylohyoid muscle and the anterior belly of the digastric muscle.
  3. Connective Tissue:

    • Loose Areolar Connective Tissue: This tissue provides a supportive framework for the structures within the pterygomandibular space and allows for some degree of movement and flexibility.

Clinical Significance

  • Local Anesthesia: The pterygomandibular space is a common site for administering local anesthesia, particularly for inferior alveolar nerve blocks, which are essential for dental procedures involving the lower jaw.
  • Infection Spread: Due to its anatomical connections, infections in the pterygomandibular space can spread to adjacent areas, including the parotid gland and the pharyngeal spaces, necessitating careful evaluation and management.
  • Surgical Considerations: Knowledge of the boundaries and contents of this space is crucial during surgical procedures in the mandible and surrounding areas to avoid damaging important nerves and vessels.

Alcohols as Antiseptics

Ethanol and isopropyl alcohol are commonly used as antiseptics in various healthcare settings. They possess antibacterial properties and are effective against a range of microorganisms, although they have limitations in their effectiveness against certain pathogens.

Mechanism of Action

  • Antibacterial Activity: Alcohols exhibit antibacterial activity against both gram-positive and gram-negative bacteria, including Mycobacterium tuberculosis.
  • Protein Denaturation: The primary mechanism by which alcohols exert their antimicrobial effects is through the denaturation of proteins. This disrupts cellular structures and functions, leading to cell death.

Effectiveness and Recommendations

  1. Contact Time:

    • According to Spaulding (1939), for alcohol to achieve maximum effectiveness, it must remain in contact with the microorganisms for at least 10 minutes. This extended contact time is crucial for ensuring adequate antimicrobial action.
  2. Concentration:

    • Solutions of 70% alcohol are more effective than higher concentrations (e.g., 90% or 100%). The presence of water in the 70% solution enhances the denaturation process of proteins, as reported by Lawrence and Block (1968). Water acts as a co-solvent, allowing for better penetration and interaction with microbial cells.

  • Subdural hemorrhage: Due to cortical vessel disruption or brain laceration.
  • Hypertensive intracranial bleed: Most common site is putamen.
  • Skin graft survival (48 hrs): Via plasma imbibition.
  • Necrotizing fasciitis: Rapid bacterial infection sparing muscle.
  • Psammoma bodies: Seen in papillary carcinoma.
  • Follicular carcinoma treatment: Hemithyroidectomy.
  • Nitroglycerin sublingual route: Ensures fast absorption & action.
  • LeFort I osteotomy blood supply: Maintained by ascending pharyngeal artery.
  • Sequestrum in osteomyelitis: Appears more radiopaque.

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