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

Axial Compression in Bone Fixation

Axial compression refers to a surgical technique used in the fixation of fractured bones, where the bony ends are brought into close proximity, minimizing the inter-fragmentary gap. This technique is crucial for achieving stable fixation and promoting optimal healing of fractures, particularly in the context of internal fixation using plates and screws.

Key Concepts of Axial Compression

  1. Close Proximity of Bony Ends:

    • In axial compression, the fractured ends of the bone are aligned closely together, which is essential for effective healing. The minimal inter-fragmentary gap allows for direct contact between the bone surfaces, facilitating the healing process.
  2. Functional Dynamic Forces:

    • During normal activities, such as chewing (masticatory function), dynamic forces are generated. These forces can create stress at the fracture site, which must be countered by the static forces provided by the fixation devices (plates and screws).
  3. Static Forces from Plates and Screws:

    • The stability of the fracture fixation relies on the ability of the plates and screws to provide sufficient static forces to counteract the dynamic forces generated during function. This is critical for maintaining the alignment of the fracture and preventing displacement.
  4. Plate and Screw Specifications:

    • Plate Thickness: Plates with a thickness of 2 mm are commonly used, as they provide adequate strength and stability while minimizing soft tissue irritation.
    • Screw Specifications: Bi-cortical screws with a diameter of 2.7 mm are typically employed. These screws engage both cortices of the bone, enhancing stability and fixation strength.
  5. Principle of Inclined Plane:

    • The design of the holes in the plate and the head of the screws operates on the principle of an inclined plane. This design allows for the application of compressive forces when the screws are tightened, effectively drawing the bony fragments together.
    • As the screws are tightened, they create a compressive force that helps to stabilize the fracture and maintain the alignment of the bone fragments.

Advantages of Axial Compression

  • Enhanced Stability: By minimizing the inter-fragmentary gap and providing strong static forces, axial compression enhances the stability of the fracture fixation.
  • Promotes Healing: Close approximation of the bony ends facilitates the healing process by allowing for direct contact and reducing the risk of non-union or malunion.
  • Functional Restoration: Effective axial compression allows patients to regain function more quickly, as the fixation can withstand the dynamic forces generated during normal activities.

Indications for PDL Injection

  1. Primary Indications:

    • Localized Anesthesia: Effective for one or two mandibular teeth in a quadrant.
    • Isolated Teeth Treatment: Useful for treating isolated teeth in both mandibular quadrants, avoiding the need for bilateral inferior alveolar nerve blocks.
    • Pediatric Dentistry: Minimizes the risk of self-inflicted injuries due to residual soft tissue anesthesia.
    • Contraindications for Nerve Blocks: Safe alternative for patients with conditions like hemophilia where nerve blocks may pose risks.
    • Diagnostic Aid: Can assist in the localization of mandibular pain.
  2. Advantages:

    • Reduced risk of complications associated with nerve blocks.
    • Faster onset of anesthesia for localized procedures.

Contraindications and Complications of PDL Injection

  1. Contraindications:

    • Infection or Severe Inflammation: Risks associated with injecting into infected or inflamed tissues.
    • Presence of Primary Teeth: Discuss the findings by Brannstrom and associates regarding enamel hypoplasia or hypomineralization in permanent teeth following PDL injections in primary dentition.
  2. Complications:

    • Potential for discomfort or pain at the injection site.
    • Risk of damage to surrounding structures if not administered correctly.
    • Discussion of the rare but serious complications associated with PDL injections.
  3. Management of Complications:

    • Strategies for minimizing risks and managing complications if they arise.

Approaches to the Oral Cavity in Oral Cancer Treatment

In the management of oral cancer, surgical approaches are tailored to the location and extent of the lesions. The choice of surgical technique is crucial for achieving adequate tumor resection while preserving surrounding structures and function. Below are the primary surgical approaches used in the treatment of oral cancer:

1. Peroral Approach

  • Indication: This approach is primarily used for small, anteriorly placed lesions within the oral cavity.
  • Technique: The surgeon accesses the lesion directly through the mouth without external incisions. This method is less invasive and is suitable for superficial lesions that do not require extensive resection.
  • Advantages:
    • Minimal morbidity and scarring.
    • Shorter recovery time.
  • Limitations: Not suitable for larger or posterior lesions due to limited visibility and access.

2. Lip Split Approach

  • Indication: This approach is utilized for posteriorly based lesions in the gingivobuccal complex and for performing marginal mandibulectomy.
  • Technique: A vertical incision is made through the lip, allowing for the elevation of a cheek flap. This provides better access to the posterior aspects of the oral cavity and the mandible.
  • Advantages:
    • Improved access to the posterior oral cavity.
    • Facilitates the removal of larger lesions and allows for better visualization of the surgical field.
  • Limitations: Potential for cosmetic concerns and longer recovery time compared to peroral approaches.

3. Pull-Through Approach

  • Indication: This technique is particularly useful for lesions of the tongue and floor of the mouth, especially when the posterior margin is a concern for peroral excision.
  • Technique: The lesion is accessed by pulling the tongue or floor of the mouth forward, allowing for better exposure and resection of the tumor while ensuring adequate margins.
  • Advantages:
    • Enhanced visibility and access to the posterior margins of the lesion.
    • Allows for more precise excision of tumors located in challenging areas.
  • Limitations: May require additional incisions or manipulation of surrounding tissues, which can increase recovery time.

4. Mandibulotomy (Median or Paramedian)

  • Indication: This approach is indicated for tongue and floor of mouth lesions that are close to the mandible, particularly when achieving a lateral margin of clearance is critical.
  • Technique: A mandibulotomy involves making an incision through the mandible, either in the midline (median) or slightly off-center (paramedian), to gain access to the oral cavity and the lesion.
  • Advantages:
    • Provides excellent access to deep-seated lesions and allows for adequate resection with clear margins.
    • Facilitates reconstruction if needed.
  • Limitations: Higher morbidity associated with mandibular manipulation, including potential complications such as nonunion or malocclusion.

Classification of Mandibular Fractures

Mandibular fractures are common injuries that can result from various causes, including trauma, accidents, and sports injuries. Understanding the classification and common sites of mandibular fractures is essential for effective diagnosis and management. Below is a detailed overview of the classification of mandibular fractures, focusing on the common sites and patterns of fracture.

General Overview

  • Weak Points: The mandible has specific areas that are more susceptible to fractures due to their anatomical structure. The condylar neck is considered the weakest point and the most common site of mandibular fractures. Other common sites include the angle of the mandible and the region of the canine tooth.

  • Indirect Transmission of Energy: Fractures can occur due to indirect forces transmitted through the mandible, which may lead to fractures of the condyle even if the impact is not directly on that area.

Patterns of Mandibular Fractures

  1. Fracture of the Condylar Neck:

    • Description: The neck of the condyle is the most common site for mandibular fractures. This area is particularly vulnerable due to its anatomical structure and the forces applied during trauma.
    • Clinical Significance: Fractures in this area can affect the function of the temporomandibular joint (TMJ) and may lead to complications such as malocclusion or limited jaw movement.
  2. Fracture of the Angle of the Mandible:

    • Description: The angle of the mandible is the second most common site for fractures, typically occurring through the last molar tooth.
    • Clinical Significance: Fractures in this region can impact the integrity of the mandible and may lead to displacement of the fractured segments. They can also affect the function of the muscles of mastication.
  3. Fracture in the Region of the Canine Tooth:

    • Description: The canine region is another weak point in the mandible, where fractures can occur due to trauma.
    • Clinical Significance: Fractures in this area may involve the alveolar process and can affect the stability of the canine tooth, leading to potential complications in dental alignment and occlusion.

Additional Classification Systems

Mandibular fractures can also be classified based on various criteria, including:

  1. Location:

    • Symphyseal Fractures: Fractures occurring at the midline of the mandible.
    • Parasymphyseal Fractures: Fractures located just lateral to the midline.
    • Body Fractures: Fractures occurring along the body of the mandible.
    • Angle Fractures: Fractures at the angle of the mandible.
    • Condylar Fractures: Fractures involving the condylar process.
  2. Type of Fracture:

    • Simple Fractures: Fractures that do not involve the surrounding soft tissues.
    • Compound Fractures: Fractures that communicate with the oral cavity or skin, leading to potential infection.
    • Comminuted Fractures: Fractures that result in multiple fragments of bone.
  3. Displacement:

    • Non-displaced Fractures: Fractures where the bone fragments remain in alignment.
    • Displaced Fractures: Fractures where the bone fragments are misaligned, requiring surgical intervention for realignment.

  • Gow – Gates landmarks:
    • Corner of mouth
    • Disto – palatal cusp of maxillary 2nd molar
    • Neck of condyle
    • Extraoral: Lower border of tragus
  • Laryngeal mask airway (LMA): Supraglottic device
  • Tracheostomy incision: 4–5 cm below cricoid cartilage
  • Common tracheostomy complications:
    • Peri – op: Anterior jugular vein injury
    • Late: Innominate artery fistula

Common Causes in Oral Surgery

  • Tongue displacement: Loss of muscle tone, posterior collapse
  • Blood/debris: From surgical procedures
  • Edema: Post-operative swelling, allergic reactions
  • Foreign bodies: Gauze, tooth fragments, instruments
  • Laryngospasm: Reflex closure of vocal cords
  • Bronchospasm: Lower airway constriction

Signs of Airway Compromise

Early Signs

  • Stridor: Inspiratory (upper airway), expiratory (lower airway)
  • Increased respiratory effort: Accessory muscle use
  • Anxiety/agitation: Hypoxemia, hypercarbia
  • Voice changes: Hoarseness, muffled speech
  • Cyanosis: Central (lips, tongue) vs peripheral

Late Signs (Impending Respiratory Arrest)

  • Bradycardia: From severe hypoxemia
  • Hypotension: Cardiovascular compromise
  • Altered consciousness: Confusion, somnolence
  • Paradoxical breathing: Chest-abdomen dyscoordination
  • Silent chest: Absent air movement despite effort

Mandibular 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

  1. 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.
  2. 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.
  3. 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

  1. 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.
  2. 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.
  3. 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.
  4. 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.
  5. Follow-Up:

    • Regular follow-up appointments are necessary to monitor healing and assess for any potential complications, such as infection or delayed healing.

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