NEET MDS Lessons
Oral and Maxillofacial Surgery
Vestibuloplasty
Vestibuloplasty is a surgical procedure aimed at deepening the vestibule of the oral cavity, which is the space between the gums and the inner lining of the lips and cheeks. This procedure is particularly important in prosthodontics and oral surgery, as it can enhance the retention and stability of dentures by increasing the available denture-bearing area.
Types of Vestibuloplasty
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Vestibuloplasty (Sulcoplasty or Sulcus Deepening Procedure):
- This procedure involves deepening the vestibule without the addition of bone. It is primarily focused on modifying the soft tissue to create a more favorable environment for denture placement.
- Indications:
- Patients with shallow vestibules that may compromise denture retention.
- Patients requiring improved aesthetics and function of their prostheses.
- Technique:
- The procedure typically involves the excision of the mucosa and submucosal tissue to create a deeper vestibule.
- The soft tissue is then repositioned to allow for a deeper sulcus, enhancing the area available for denture support.
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Labial Vestibular Procedure (Transpositional Flap Vestibuloplasty or Lip Switch Procedure):
- This specific type of vestibuloplasty involves the transposition of soft tissue from the inner aspect of the lip to a more favorable position on the alveolar bone.
- Indications:
- Patients with inadequate vestibular depth who require additional soft tissue coverage for denture support.
- Cases where the labial vestibule is shallow, affecting the retention of dentures.
- Technique:
- A flap is created from the inner lip, which is then mobilized and repositioned to cover the alveolar ridge.
- This procedure increases the denture-bearing area by utilizing the soft tissue from the lip, thereby enhancing the retention and stability of the denture.
- The flap is sutured into place, and the healing process allows for the integration of the new tissue position.
Benefits of Vestibuloplasty
- Increased Denture Retention: By deepening the vestibule and increasing the denture-bearing area, patients often experience improved retention and stability of their dentures.
- Enhanced Aesthetics: The procedure can improve the overall appearance of the oral cavity, contributing to better facial aesthetics.
- Improved Function: Patients may find it easier to eat and speak with well-retained dentures, leading to improved quality of life.
Considerations and Postoperative Care
- Healing Time: Patients should be informed about the expected healing time and the importance of following postoperative care instructions to ensure proper healing.
- Follow-Up: Regular follow-up appointments may be necessary to monitor healing and assess the need for any adjustments to the dentures.
- Potential Complications: As with any surgical procedure, there are risks involved, including infection, bleeding, and inadequate healing. Proper surgical technique and postoperative care can help mitigate these risks.
Champy Technique of Fracture Stabilization
The Champy technique, developed by Champy et al. in the mid-1970s, is a method of fracture stabilization that utilizes non-compression monocortical miniplates applied as tension bands. This technique is particularly relevant in the context of mandibular fractures and is based on biomechanical principles that optimize the stability and healing of the bone.
Key Principles of the Champy Technique
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Biomechanical Considerations:
- Tensile and Compressive Stresses: Biomechanical studies have shown that tensile stresses occur in the upper border of the mandible, while compressive stresses are found in the lower border. This understanding is crucial for the placement of plates.
- Bending and Torsional Forces: The forces acting on the mandible primarily produce bending movements. In the symphysis and parasymphysis regions, torsional forces are more significant than bending moments.
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Ideal Osteosynthesis Line:
- Champy et al. established the "ideal osteosynthesis line" at the base of the alveolar process. This line is critical for the effective placement of plates to ensure stability during the healing process.
- Plate Placement:
- Anterior Region: In the area between the mental foramina, a subapical plate is placed, and an additional plate is positioned near the lower border of the mandible to counteract torsional forces.
- Posterior Region: Behind the mental foramen, the plate is applied just below the dental roots and above the inferior alveolar nerve.
- Angle of Mandible: The plate is placed on the broad surface of the external oblique ridge.
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Tension Band Principle:
- The use of miniplates as tension bands allows for the distribution of forces across the fracture site, enhancing stability and promoting healing.
Treatment Steps
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Reduction:
- The first step in fracture treatment is the accurate reduction of the fracture fragments to restore normal anatomy.
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Stabilization:
- Following reduction, stabilization is achieved using the Champy technique, which involves the application of miniplates in accordance with the biomechanical principles outlined above.
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Maxillomandibular Fixation (MMF):
- MMF is often used as a standard method for both reduction and stabilization, particularly in cases where additional support is needed.
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External Fixation:
- In cases of atrophic edentulous mandibular fractures, extensive soft tissue injuries, severe communication, or infected fractures, external fixation may be considered.
Classification of Internal Fixation Techniques
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Absolute Stability:
- Rigid internal fixation methods, such as compression plates, lag screws, and the tension band principle, fall under this category. These techniques provide strong stabilization but may compromise blood supply to the bone.
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Relative Stability:
- Techniques such as bridging, biologic (flexible) fixation, and the Champy technique are classified as relative stability methods. These techniques allow for some movement at the fracture site, which can promote healing by maintaining blood supply to the cortical bone.
Biologic Fixation
- New Paradigm:
- Biologic fixation represents a shift in fracture treatment philosophy, emphasizing that absolute stability is not always beneficial. Allowing for some movement at the fracture site can enhance blood supply and promote healing.
- Improved Blood Supply:
- Not pressing the plate against the bone helps maintain blood supply to the cortical bone and prevents the formation of early temporary porosity, which can be detrimental to healing.
Le Fort I Fracture
- A horizontal fracture that separates the maxilla from the nasal and zygomatic bones. It is also known as a "floating maxilla."
Signs and Symptoms:
- Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
- Disturbed Occlusion: Malocclusion due to displacement of the maxilla.
- Mobility of the Maxilla: The maxilla may move independently of the rest of the facial skeleton.
- Nasal Bleeding: Possible epistaxis due to injury to the nasal mucosa.
- CSF Rhinorrhea: If there is a breach in the dura mater, cerebrospinal fluid may leak from the nose.
Le Fort II Fracture
- A pyramidal fracture that involves the maxilla, nasal bones, and the zygomatic bones. It is characterized by a fracture line that extends from the nasal bridge to the maxilla and zygomatic arch.
Signs and Symptoms:
- Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
- Diplopia: Double vision due to involvement of the orbital floor and potential muscle entrapment.
- Enophthalmos: Posterior displacement of the eyeball within the orbit.
- Restriction of Globe Movements: Limited eye movement due to muscle entrapment.
- Disturbed Occlusion: Malocclusion due to displacement of the maxilla.
- Nasal Bleeding: Possible epistaxis.
- CSF Rhinorrhea: If the dura is torn, cerebrospinal fluid may leak from the nose.
Le Fort III Fracture
- A craniofacial disjunction fracture that involves the maxilla, zygomatic bones, and the orbits. It is characterized by a fracture line that separates the entire midface from the skull base.
Signs and Symptoms:
- Bilateral Periorbital Edema and Ecchymosis: Swelling and bruising around the eyes (Raccoon eyes).
- Orbital Dystopia: Abnormal positioning of the orbits, often with an antimongoloid slant.
- Diplopia: Double vision due to muscle entrapment or damage.
- Enophthalmos: Posterior displacement of the eyeball.
- Restriction of Globe Movements: Limited eye movement due to muscle entrapment.
- Disturbed Occlusion: Significant malocclusion due to extensive displacement of facial structures.
- CSF Rhinorrhea: If there is a breach in the dura mater, cerebrospinal fluid may leak from the nose or ears (CSF otorrhea).
- Bleeding Over Mastoid Process (Battle’s Sign): Bruising behind the ear may indicate a skull base fracture.
Nasogastric Tube (Ryles Tube)
A nasogastric tube (NG tube), commonly referred to as a Ryles tube, is a medical device used for various purposes, primarily involving the stomach. It is a long, hollow tube made of polyvinyl chloride (PVC) with one blunt end and multiple openings along its length. The tube is designed to be inserted through the nostril, down the esophagus, and into the stomach.
Description and Insertion
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Structure: The NG tube has a blunt end that is inserted into the nostril, and it features multiple openings to allow for the passage of fluids and air. The open end of the tube is used for feeding or drainage.
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Insertion Technique:
- The tube is gently passed through one of the nostrils and advanced through the nasopharynx and into the esophagus.
- Care is taken to ensure that the tube follows the natural curvature of the nasal passages and esophagus.
- Once the tube is in place, its position must be confirmed before any feeds or medications are administered.
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Position Confirmation:
- To check the position of the tube, air is pushed into the tube using a syringe.
- The presence of air in the stomach is confirmed by auscultation with a stethoscope, listening for the characteristic "whoosh" sound of air entering the stomach.
- Only after confirming that the tube is correctly positioned in the stomach should feeding or medication administration begin.
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Securing the Tube: The tube is fixed to the nose using sticking plaster or adhesive tape to prevent displacement.
Uses of Nasogastric Tube
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Nutritional Support:
- Enteral Feeding: The primary use of a nasogastric
tube is to provide nutritional support to patients who are unable to
take oral feeds due to various reasons, such as:
- Neurological conditions (e.g., stroke, coma)
- Surgical procedures affecting the gastrointestinal tract
- Severe dysphagia (difficulty swallowing)
- Enteral Feeding: The primary use of a nasogastric
tube is to provide nutritional support to patients who are unable to
take oral feeds due to various reasons, such as:
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Gastric Lavage:
- Postoperative Care: NG tubes can be used for gastric lavage to flush out blood, fluids, or other contents from the stomach after surgery. This is particularly important in cases where there is a risk of aspiration or when the stomach needs to be emptied.
- Poisoning: In cases of poisoning or overdose, gastric lavage may be performed using an NG tube to remove toxic substances from the stomach. This procedure should be done promptly and under medical supervision.
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Decompression:
- Relieving Distension: The NG tube can also be used to decompress the stomach in cases of bowel obstruction or ileus, allowing for the removal of excess gas and fluid.
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Medication Administration:
- The tube can be used to administer medications directly into the stomach for patients who cannot take oral medications.
Considerations and Complications
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Patient Comfort: Insertion of the NG tube can be uncomfortable for patients, and proper technique should be used to minimize discomfort.
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Complications: Potential complications include:
- Nasal and esophageal irritation or injury
- Misplacement of the tube into the lungs, leading to aspiration
- Sinusitis or nasal ulceration with prolonged use
- Gastrointestinal complications, such as gastric erosion or ulceration
Submasseteric Space Infection
Submasseteric space infection refers to an infection that occurs in the submasseteric space, which is located beneath the masseter muscle. This space is clinically significant in the context of dental infections, particularly those arising from the lower third molars (wisdom teeth) or other odontogenic sources. Understanding the anatomy and potential spread of infections in this area is crucial for effective diagnosis and management.
Anatomy of the Submasseteric Space
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Location:
- The submasseteric space is situated beneath the masseter muscle, which is a major muscle involved in mastication (chewing).
- This space is bordered superiorly by the masseter muscle and inferiorly by the lower border of the ramus of the mandible.
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Boundaries:
- Inferior Boundary: The extension of an abscess or infection inferiorly is limited by the firm attachment of the masseter muscle to the lower border of the ramus of the mandible. This attachment creates a barrier that can restrict the spread of infection downward.
- Anterior Boundary: The forward spread of infection beyond the anterior border of the ramus is restricted by the anterior tail of the tendon of the temporalis muscle, which inserts into the anterior border of the ramus. This anatomical feature helps to contain infections within the submasseteric space.
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Posterior Boundary: The posterior limit of the submasseteric space is generally defined by the posterior border of the ramus of the mandible.
Clinical Implications
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Sources of Infection:
- Infections in the submasseteric space often arise from odontogenic
sources, such as:
- Pericoronitis associated with impacted lower third molars.
- Dental abscesses from other teeth in the mandible.
- Periodontal infections.
- Infections in the submasseteric space often arise from odontogenic
sources, such as:
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Symptoms:
- Patients with submasseteric space infections may present with:
- Swelling and tenderness in the area of the masseter muscle.
- Limited mouth opening (trismus) due to muscle spasm or swelling.
- Pain that may radiate to the ear or temporomandibular joint (TMJ).
- Fever and systemic signs of infection in more severe cases.
- Patients with submasseteric space infections may present with:
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Diagnosis:
- Diagnosis is typically made through clinical examination and imaging studies, such as panoramic radiographs or CT scans, to assess the extent of the infection and its relationship to surrounding structures.
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Management:
- Treatment of submasseteric space infections usually involves:
- Antibiotic Therapy: Broad-spectrum antibiotics are often initiated to control the infection.
- Surgical Intervention: Drainage of the abscess may be necessary, especially if there is significant swelling or if the patient is not responding to conservative management. Incision and drainage can be performed intraorally or extraorally, depending on the extent of the infection.
- Management of the Source: Addressing the underlying dental issue, such as extraction of an impacted tooth or treatment of a dental abscess, is essential to prevent recurrence.
- Treatment of submasseteric space infections usually involves:
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.
Sagittal Split Osteotomy (SSO)
Sagittal split osteotomy (SSO) is a surgical procedure used to correct various mandibular deformities, including mandibular prognathism (protrusion of the mandible) and retrognathism (retraction of the mandible). It is considered one of the most versatile osteotomies for addressing discrepancies in the position of the mandible relative to the maxilla.
Overview of the Procedure
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Indications:
- Mandibular Prognathism: In cases where the mandible is positioned too far forward, SSO can be used to setback the mandible, improving occlusion and facial aesthetics.
- Mandibular Retrognathism: For patients with a retruded mandible, the procedure allows for advancement of the mandible to achieve a more balanced facial profile and functional occlusion.
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Surgical Technique:
- The procedure involves making a sagittal split in the ramus and posterior body of the mandible. This is typically performed through an intraoral approach, which minimizes external scarring.
- The osteotomy creates two segments of the mandible: the proximal segment (attached to the maxilla) and the distal segment (which can be repositioned).
- Depending on the desired outcome, the distal segment can be either advanced or set back to achieve the desired occlusal relationship and aesthetic result.
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Cosmetic Considerations:
- The intraoral approach used in SSO helps to avoid visible scarring on the face, making it a highly cosmetic procedure.
- The broader bony contact between the osteotomized segments promotes better healing and stability, which is crucial for achieving long-term results.
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Healing and Recovery:
- The procedure typically results in good healing due to the increased surface area of contact between the bone segments.
- Postoperative care includes monitoring for complications, managing pain, and ensuring proper oral hygiene to prevent infection.
Advantages of Sagittal Split Osteotomy
- Versatility: SSO can be used to correct a wide range of mandibular discrepancies, making it suitable for various clinical scenarios.
- Cosmetic Outcome: The intraoral approach minimizes external scarring, enhancing the aesthetic outcome for patients.
- Stability: The broad bony contact between the segments ensures good stability and promotes effective healing.
- Functional Improvement: By correcting occlusal discrepancies, SSO can improve chewing function and overall oral health.
Considerations and Potential Complications
- Nerve Injury: There is a risk of injury to the inferior alveolar nerve, which can lead to temporary or permanent numbness in the lower lip and chin.
- Malocclusion: If not properly planned, there is a risk of postoperative malocclusion, which may require further intervention.
- Infection: As with any surgical procedure, there is a risk of infection at the surgical site.