NEET MDS Lessons
Oral and Maxillofacial Surgery
Fixation of Condylar Fractures
Condylar fractures of the mandible can be challenging to manage due to their location and the functional demands placed on the condylar region. Various fixation techniques have been developed to achieve stable fixation and promote healing. Below is an overview of the different methods of fixation for condylar fractures, including their advantages, disadvantages, and indications.
1. Miniplate Osteosynthesis
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Overview:
- Miniplate osteosynthesis involves the use of condylar plates and screw systems designed to withstand biochemical forces, minimizing micromotion at the fracture site.
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Primary Bone Healing:
- Under optimal conditions of stability and fracture reduction, primary bone healing can occur, allowing new bone to form along the fracture surface without the formation of fibrous tissue.
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Plate Placement:
- High condylar fractures may accommodate only one plate with two screws above and below the fracture line, parallel to the posterior border, providing adequate stability in most cases.
- For low condylar fractures, two plates may be required. The posterior plate should parallel the posterior ascending ramus, while the anterior plate can be angulated across the fracture line.
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Mechanical Advantage:
- The use of two miniplates at the anterior and posterior borders of the condylar neck restores tension and compression trajectories, neutralizing functional stresses in the condylar neck.
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Research Findings:
- Studies have shown that the double mini plate method is the only system able to withstand normal loading forces in cadaver mandibles.
2. Dynamic Compression Plating
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Overview:
- Dynamic compression plating is generally not recommended for condylar fractures due to the oblique nature of the fractures, which can lead to overlap of fragment ends and loss of ramus height.
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Current Practice:
- The consensus is that treatment is adequate with miniplates placed in a neutral mode, avoiding the complications associated with dynamic compression plating.
3. Lag Screw Osteosynthesis
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Overview:
- First described for condylar fractures by Wackerbauer in 1962, lag screws provide a biomechanically advantageous method of fixation.
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Mechanism:
- A true lag screw has threads only on the distal end, allowing for compression when tightened against the near cortex. This central placement of the screw enhances stability.
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Advantages:
- Rapid application of rigid fixation and close approximation of fractured parts due to significant compression generated.
- Less traumatic than miniplates, as there is no need to open the joint capsule.
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Disadvantages:
- Risk of lateralization and rotation of the condylar head if the screw is not placed centrally.
- Requires a steep learning curve for proper application.
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Contraindications:
- Not suitable for cases with loss of bone in the fracture gap or comminution that could lead to displacement when compression is applied.
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Popular Options:
- The Eckelt screw is one of the most widely used lag screws in current practice.
4. Pin Fixation
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Overview:
- Pin fixation involves the use of 1.3 mm Kirschner wires (K-wires) placed into the condyle under direct vision.
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Technique:
- This method requires an open approach to the condylar head and traction applied to the lower border of the mandible. A minimum of three convergent K-wires is typically needed to ensure stability.
5. Resorbable Pins and Plates
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Overview:
- Resorbable fixation devices may take more than two years to fully resorb. Materials used include self-reinforced poly-L-lactide screws (SR-PLLA), polyglycolide pins, and absorbable alpha-hydroxy polyesters.
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Indications:
- These materials are particularly useful in pediatric patients or in situations where permanent hardware may not be desirable.
Sjögren's Syndrome and Sialography
Sjögren's syndrome is an autoimmune disorder characterized by the destruction of exocrine glands, particularly the salivary and lacrimal glands, leading to dry mouth (xerostomia) and dry eyes (keratoconjunctivitis sicca). One of the diagnostic tools used to evaluate the salivary glands in patients with Sjögren's syndrome is sialography.
Sialography Findings in Sjögren's Syndrome
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Sialectasis: In sialography, Sjögren's syndrome is often associated with sialectasis, which refers to the dilation of the salivary gland ducts. This occurs due to the inflammatory changes and damage to the ductal system.
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"Cherry Blossom" Appearance: The sialographic findings in Sjögren's syndrome can produce a characteristic appearance described as:
- "Cherry Blossom" or "Branchless Fruit Laden Tree": This appearance is due to the presence of many large dye-filled spaces within the salivary glands. The pattern resembles the branches of a tree laden with fruit, where the dye fills the dilated ducts and spaces, creating a striking visual effect.
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Mechanism: The appearance is thought to result from the dye passing through weakened or damaged salivary gland ducts, which are unable to properly transport saliva due to the underlying pathology of the syndrome. The inflammation and fibrosis associated with Sjögren's syndrome lead to ductal obstruction and dilation.
Clinical Significance
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Diagnosis: The characteristic sialographic appearance can aid in the diagnosis of Sjögren's syndrome, especially when combined with clinical findings and other diagnostic tests (e.g., labial salivary gland biopsy).
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Management: Understanding the changes in the salivary glands can help guide management strategies for patients, including the use of saliva substitutes, medications to stimulate saliva production, and regular dental care to prevent complications associated with dry mouth.
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
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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.
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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.
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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
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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.
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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.
- It is crucial not to make the incision directly over the torus.
Incising over the torus can lead to:
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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.
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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.
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Follow-Up:
- Regular follow-up appointments are necessary to monitor healing and assess for any potential complications, such as infection or delayed healing.
Ludwig's Angina
Ludwig's angina is a serious, potentially life-threatening cellulitis or connective tissue infection of the submandibular space. It is characterized by bilateral swelling of the submandibular and sublingual areas, which can lead to airway obstruction. The condition is named after the German physician Wilhelm Friedrich Ludwig, who provided a classic description of the disease in the early 19th century.
Historical Background
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Coining of the Term: The term "Ludwig's angina" was first coined by Camerer in 1837, who presented cases that included a classic description of the condition. The name honors W.F. Ludwig, who had described the features of the disease in the previous year.
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Etymology:
- The word "angina" is derived from the Latin word "angere," which means "to suffocate" or "to choke." This reflects the potential for airway compromise associated with the condition.
- The name "Ludwig" recognizes the contributions of Wilhelm Friedrich Ludwig to the understanding of this medical entity.
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Ludwig's Personal Connection: Interestingly, Ludwig himself died of throat inflammation in 1865, which underscores the severity of infections in the head and neck region.
Clinical Features
Ludwig's angina typically presents with the following features:
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Bilateral Swelling: The most characteristic sign is bilateral swelling of the submandibular area, which can extend to the sublingual space. This swelling may cause the floor of the mouth to elevate.
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Pain and Tenderness: Patients often experience pain and tenderness in the affected area, which may worsen with movement or swallowing.
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Dysphagia and Dysarthria: Difficulty swallowing (dysphagia) and changes in speech (dysarthria) may occur due to swelling and discomfort.
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Airway Compromise: As the swelling progresses, there is a risk of airway obstruction, which can be life-threatening. Patients may exhibit signs of respiratory distress.
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Systemic Symptoms: Fever, malaise, and other systemic signs of infection may be present.
Etiology
Ludwig's angina is most commonly caused by infections that originate from the teeth, particularly the second or third molars. The infection can spread from dental abscesses or periodontal disease into the submandibular space. The most common pathogens include:
- Streptococcus species
- Staphylococcus aureus
- Anaerobic bacteria
Diagnosis and Management
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Diagnosis: Diagnosis is primarily clinical, based on the characteristic signs and symptoms. Imaging studies, such as CT scans, may be used to assess the extent of the infection and to rule out other conditions.
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Management:
- Airway Management: Ensuring a patent airway is the top priority, especially if there are signs of respiratory distress.
- Antibiotic Therapy: Broad-spectrum intravenous antibiotics are initiated to target the likely pathogens.
- Surgical Intervention: In cases of significant swelling or abscess formation, surgical drainage may be necessary to relieve pressure and remove infected material.
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
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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.
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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.
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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.
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Anteriorly:
- Pterygomandibular Raphe: This fibrous band connects the pterygoid muscles and serves as the anterior boundary of the space.
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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:
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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.
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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.
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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.
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
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Composition: Gelfoam is made from gelatin and has a sponge-like structure.
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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.
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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.
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Absorption: Gelfoam is absorbed by the body through phagocytosis, typically within a few weeks.
2. Oxycel
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Composition: Oxycel is made from oxidized cellulose.
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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.
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Limitations:
- The acid produced can inhibit epithelialization, making Oxycel unsuitable for use over epithelial surfaces.
3. Surgical (Oxycellulose)
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Composition: Surgical is a glucose polymer-based sterile knitted fabric created through the controlled oxidation of regenerated cellulose.
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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.
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Application:
- Surgical can be applied dry or soaked in thrombin solution, providing flexibility in its use.
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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
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Composition: Fibrin glue is a biological adhesive that contains thrombin, fibrinogen, factor XIII, and aprotinin.
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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.
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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.
Trigeminal Neuralgia
Trigeminal neuralgia (TN) is a type of orofacial neuralgia characterized by severe, paroxysmal pain that follows the anatomical distribution of the trigeminal nerve (cranial nerve V). It is often described as one of the most painful conditions known, and understanding its features, triggers, and patterns is essential for effective management.
Features of Trigeminal Neuralgia
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Anatomical Distribution:
- Trigeminal neuralgia follows the distribution of the trigeminal
nerve, which has three main branches:
- V1 (Ophthalmic): Supplies sensation to the forehead, upper eyelid, and parts of the nose.
- V2 (Maxillary): Supplies sensation to the cheeks, upper lip, and upper teeth.
- V3 (Mandibular): Supplies sensation to the lower lip, chin, and lower teeth.
- Pain can occur in one or more of these dermatomes, but it is typically unilateral.
- Trigeminal neuralgia follows the distribution of the trigeminal
nerve, which has three main branches:
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Trigger Zones:
- Patients with trigeminal neuralgia often have specific trigger zones on the face. These are areas where light touch, brushing, or even wind can provoke an episode of pain.
- Stimulation of these trigger zones can initiate a paroxysm of pain, leading to sudden and intense discomfort.
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Pain Characteristics:
- The pain associated with trigeminal neuralgia is described as:
- Paroxysmal: Occurs in sudden bursts or attacks.
- Excruciating: The pain is often severe and debilitating.
- Sharp, shooting, or lancinating: Patients may describe the pain as electric shock-like.
- Unilateral: Pain typically affects one side of the face.
- Intermittent: Attacks can vary in frequency and duration.
- The pain associated with trigeminal neuralgia is described as:
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Latency and Refractory Period:
- Latency: This refers to the short time interval between the stimulation of the trigger area and the onset of pain. It can vary among patients.
- Refractory Period: After an attack, there may be a refractory period during which further stimulation does not elicit pain. This period can vary in length and is an important aspect of the pain cycle.
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Pain Cycles:
- Paroxysms of pain often occur in cycles, with each cycle lasting for weeks or months. Over time, these cycles may become more frequent, and the intensity of pain can increase with each attack.
- Patients may experience a progressive worsening of symptoms, leading to more frequent and severe episodes.
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Psychosocial Impact:
- The unpredictable nature of trigeminal neuralgia can significantly impact a patient's quality of life, leading to anxiety, depression, and social withdrawal due to fear of triggering an attack.
Management of Trigeminal Neuralgia
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Medications:
- Anticonvulsants: Medications such as carbamazepine and oxcarbazepine are commonly used as first-line treatments to help control pain.
- Other Medications: Gabapentin, pregabalin, and baclofen may also be effective in managing symptoms.
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Surgical Options:
- For patients who do not respond to medication or experience
intolerable side effects, surgical options may be considered. These can
include:
- Microvascular Decompression: A surgical procedure that relieves pressure on the trigeminal nerve.
- Rhizotomy: A procedure that selectively destroys nerve fibers to reduce pain.
- For patients who do not respond to medication or experience
intolerable side effects, surgical options may be considered. These can
include:
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Alternative Therapies:
- Some patients may benefit from complementary therapies such as acupuncture, physical therapy, or biofeedback.