NEET MDS Lessons
Oral and Maxillofacial Surgery
Basic Principles of Treatment of a Fracture
The treatment of fractures involves a systematic approach to restore the normal anatomy and function of the affected bone. The basic principles of fracture treatment can be summarized in three key steps: reduction, fixation, and immobilization.
1. Reduction
Definition: Reduction is the process of restoring the fractured bone fragments to their original anatomical position.
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Methods of Reduction:
- Closed Reduction: This technique involves
realigning the bone fragments without direct visualization of the
fracture line. It can be achieved through:
- Reduction by Manipulation: The physician uses manual techniques to manipulate the bone fragments into alignment.
- Reduction by Traction: Gentle pulling forces are applied to align the fragments, often used in conjunction with other methods.
- Closed Reduction: This technique involves
realigning the bone fragments without direct visualization of the
fracture line. It can be achieved through:
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Open Reduction: In some cases, if closed reduction is not successful or if the fracture is complex, an open reduction may be necessary. This involves surgical exposure of the fracture site to directly visualize and align the fragments.
2. Fixation
Definition: After reduction, fixation is the process of stabilizing the fractured fragments in their normal anatomical relationship to prevent displacement and ensure proper healing.
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Types of Fixation:
- Internal Fixation: This involves the use of devices such as plates, screws, or intramedullary nails that are placed inside the body to stabilize the fracture.
- External Fixation: This method uses external devices, such as pins or frames, that are attached to the bone through the skin. External fixation is often used in cases of open fractures or when internal fixation is not feasible.
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Goals of Fixation: The primary goals are to maintain the alignment of the bone fragments, prevent movement at the fracture site, and facilitate healing.
3. Immobilization
Definition: Immobilization is the phase during which the fixation device is retained to stabilize the reduced fragments until clinical bony union occurs.
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Duration of Immobilization: The length of the immobilization period varies depending on the type of fracture and the bone involved:
- Maxillary Fractures: Typically require 3 to 4 weeks of immobilization.
- Mandibular Fractures: Generally require 4 to 6 weeks of immobilization.
- Condylar Fractures: Recommended immobilization period is 2 to 3 weeks to prevent temporomandibular joint (TMJ) ankylosis.
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Maxillectomy
Maxillectomy is a surgical procedure involving the resection of the maxilla (upper jaw) and is typically performed to remove tumors, treat severe infections, or address other pathological conditions affecting the maxillary region. The procedure requires careful planning and execution to ensure adequate access, removal of the affected tissue, and preservation of surrounding structures for optimal functional and aesthetic outcomes.
Surgical Access and Incision
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Weber-Fergusson Incision:
- The classic approach to access the maxilla is through the Weber-Fergusson incision. This incision provides good visibility and access to the maxillary region.
- Temporary Tarsorrhaphy: The eyelids are temporarily closed using tarsorrhaphy sutures to protect the eye during the procedure.
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Tattooing for Aesthetic Alignment:
- To achieve better cosmetic results, it is recommended to tattoo the vermilion border and other key points on both sides of the incision with methylene blue. These points serve as guides for alignment during closure.
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Incision Design:
- The incision typically splits the midline of the upper lip but can be modified for better cosmetic outcomes by incising along the philtral ridges and offsetting the incision at the vermilion border.
- The incision is turned 2 mm from the medial canthus of the eye. Intraorally, the incision continues through the gingival margin and connects with a horizontal incision at the depth of the labiobuccal vestibule, extending back to the maxillary tuberosity.
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Continuation of the Incision:
- From the maxillary tuberosity, the incision turns medially across the posterior edge of the hard palate and then turns 90 degrees anteriorly, several millimeters to the proximal side of the midline, crossing the gingival margin again if possible.
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Incision to Bone:
- The incision is carried down to the bone, except beneath the lower eyelid, where the orbicularis oculi muscle is preserved. The cheek flap is then reflected back to the tuberosity.
Surgical Procedure
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Extraction and Elevation:
- The central incisor on the involved side is extracted, and the gingival and palatal mucosa are elevated back to the midline.
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Deepening the Incision:
- The incision extending around the nose is deepened into the nasal cavity. The palatal bone is divided near the midline using a saw blade or bur.
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Separation of Bone:
- The basal bone is separated from the frontal process of the maxilla using an osteotome. The orbicularis oculi muscle is retracted superiorly, and the bone cut is extended across the maxilla, just below the infraorbital rim, into the zygoma.
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Maxillary Sinus:
- If the posterior wall of the maxillary sinus has not been invaded by the tumor, it is separated from the pterygoid plates using a pterygoid chisel.
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Specimen Removal:
- The entire specimen is removed by severing the remaining attachments with large curved scissors placed behind the maxilla.
Postoperative Considerations
- Wound Care: Proper care of the surgical site is essential to prevent infection and promote healing.
- Rehabilitation: Patients may require rehabilitation to address functional issues related to speech, swallowing, and facial aesthetics.
- Follow-Up: Regular follow-up appointments are necessary to monitor healing and assess for any complications or recurrence of disease.
Osteomyelitis of the Jaw (OML)
Osteomyelitis of the jaw (OML) is a serious infection of the bone that can lead to significant morbidity if not properly diagnosed and treated. Understanding the etiology and microbiological profile of OML is crucial for effective management. Here’s a detailed overview based on the information provided.
Historical Perspective on Etiology
- Traditional View: In the past, the etiology of OML was primarily associated with skin surface bacteria, particularly Staphylococcus aureus. Other bacteria, such as Staphylococcus epidermidis and hemolytic streptococci, were also implicated.
- Reevaluation: Recent findings indicate that S. aureus is not the primary pathogen in cases of OML affecting tooth-bearing bone. This shift in understanding highlights the complexity of the microbial landscape in jaw infections.
Microbiological Profile
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Common Pathogens:
- Aerobic Streptococci:
- α-Hemolytic Streptococci: Particularly Streptococcus viridans, which are part of the normal oral flora and can become pathogenic under certain conditions.
- Anaerobic Streptococci: These bacteria thrive in low-oxygen environments and are significant contributors to OML.
- Other Anaerobes:
- Peptostreptococcus: A genus of anaerobic bacteria commonly found in the oral cavity.
- Fusobacterium: Another group of anaerobic bacteria that can be involved in polymicrobial infections.
- Bacteroides: These bacteria are also part of the normal flora but can cause infections when the balance is disrupted.
- Aerobic Streptococci:
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Additional Organisms:
- Gram-Negative Organisms:
- Klebsiella, Pseudomonas, and Proteus species may also be isolated in some cases, particularly in chronic or complicated infections.
- Specific Pathogens:
- Mycobacterium tuberculosis: Can cause osteomyelitis in the jaw, particularly in immunocompromised individuals.
- Treponema pallidum: The causative agent of syphilis, which can lead to specific forms of osteomyelitis.
- Actinomyces species: Known for causing actinomycosis, these bacteria can also be involved in jaw infections.
- Gram-Negative Organisms:
Polymicrobial Nature of OML
- Polymicrobial Disease: Established acute OML is
typically a polymicrobial infection, meaning it involves multiple types of
bacteria. The common bacterial constituents include:
- Streptococci (both aerobic and anaerobic)
- Bacteroides
- Peptostreptococci
- Fusobacteria
- Other opportunistic bacteria that may contribute to the infection.
Clinical Implications
- Sinus Tract Cultures: Cultures obtained from sinus tracts in the jaw may often be misleading. They can be contaminated with skin flora, such as Staphylococcus species, which do not accurately represent the pathogens responsible for the underlying osteomyelitis.
- Diagnosis and Treatment: Understanding the polymicrobial nature of OML is essential for effective diagnosis and treatment. Empirical antibiotic therapy should consider the range of potential pathogens, and cultures should be interpreted with caution.
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.
Marsupialization
Marsupialization, also known as decompression, is a surgical procedure used primarily to treat cystic lesions, particularly odontogenic cysts, by creating a surgical window in the wall of the cyst. This technique aims to reduce intracystic pressure, promote the shrinkage of the cyst, and encourage bone fill in the surrounding area.
Key Features of Marsupialization
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Indication:
- Marsupialization is indicated for large cystic lesions that are not
amenable to complete excision due to their size, location, or proximity
to vital structures. It is commonly used for:
- Odontogenic keratocysts
- Dentigerous cysts
- Radicular cysts
- Other large cystic lesions in the jaw
- Marsupialization is indicated for large cystic lesions that are not
amenable to complete excision due to their size, location, or proximity
to vital structures. It is commonly used for:
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Surgical Technique:
- Creation of a Surgical Window:
- The procedure begins with the creation of a window in the wall of the cyst. This is typically done through an intraoral approach, where an incision is made in the mucosa overlying the cyst.
- Evacuation of Cystic Content:
- The cystic contents are evacuated, which helps to decrease the intracystic pressure. This reduction in pressure is crucial for promoting the shrinkage of the cyst and facilitating bone fill.
- Suturing the Cystic Lining:
- The remaining cystic lining is sutured to the edge of the oral mucosa. This can be done using continuous sutures or interrupted sutures, depending on the surgeon's preference and the specific clinical situation.
- Creation of a Surgical Window:
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Benefits:
- Pressure Reduction: By decreasing the intracystic pressure, marsupialization can lead to the gradual reduction in the size of the cyst.
- Bone Regeneration: The procedure promotes bone fill in the area previously occupied by the cyst, which can help restore normal anatomy and function.
- Minimally Invasive: Compared to complete cyst excision, marsupialization is less invasive and can be performed with less morbidity.
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Postoperative Care:
- Patients may experience some discomfort and swelling following the procedure, which can be managed with analgesics.
- Regular follow-up appointments are necessary to monitor the healing process and assess the reduction in cyst size.
- Oral hygiene is crucial to prevent infection at the surgical site.
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Outcomes:
- Marsupialization can be an effective treatment for large cystic lesions, leading to significant reduction in size and promoting bone regeneration. In some cases, if the cyst does not resolve completely, further treatment options, including complete excision, may be considered.
Temporomandibular Joint (TMJ) Ankylosis
Definition: TMJ ankylosis is a condition characterized by the abnormal fusion of the bones that form the temporomandibular joint, leading to restricted movement of the jaw. This fusion can be either fibrous (non-bony) or bony, resulting in varying degrees of functional impairment.
Etiology
TMJ ankylosis can result from various factors, including:
- Trauma: Fractures or injuries to the jaw can lead to the development of ankylosis, particularly if there is associated soft tissue damage.
- Infection: Conditions such as osteomyelitis or septic arthritis can lead to inflammation and subsequent ankylosis of the joint.
- Congenital Conditions: Some individuals may be born with anatomical abnormalities that predispose them to ankylosis.
- Systemic Diseases: Conditions like rheumatoid arthritis or ankylosing spondylitis can affect the TMJ and lead to ankylosis.
- Previous Surgery: Surgical interventions in the area, such as those for cleft lip and palate, can sometimes result in scar tissue formation and ankylosis.
Pathophysiology
- Fibrous Ankylosis: In this type, fibrous tissue forms between the articulating surfaces of the joint, leading to limited movement. The joint surfaces remain intact but are functionally immobilized.
- Bony Ankylosis: This more severe form involves the formation of bone between the joint surfaces, resulting in complete loss of joint mobility. This can occur due to chronic inflammation or trauma.
Clinical Features
- Restricted Jaw Movement: Patients typically present with limited mouth opening (trismus), which can severely affect eating, speaking, and oral hygiene.
- Facial Asymmetry: Over time, the affected side of the face may appear smaller or less developed due to lack of movement and muscle atrophy.
- Pain and Discomfort: Patients may experience pain in the jaw, face, or neck, particularly during attempts to open the mouth.
- Difficulty with Oral Functions: Eating, swallowing, and speaking can become challenging due to limited jaw mobility.
- Clicking or Popping Sounds: In some cases, patients may report sounds during jaw movement, although this is less common in complete ankylosis.
Diagnosis
Diagnosis of TMJ ankylosis typically involves:
- Clinical Examination: Assessment of jaw movement, facial symmetry, and pain levels.
- Imaging Studies:
- X-rays: Can show joint space narrowing or bony fusion.
- CT Scans: Provide detailed images of the bone structure and can help assess the extent of ankylosis.
- MRI: Useful for evaluating soft tissue involvement and the condition of the articular disc.
Treatment
The management of TMJ ankylosis often requires surgical intervention, especially in cases of significant functional impairment. Treatment options include:
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Surgical Options:
- Arthroplasty: This procedure involves the removal of the ankylosed tissue and reconstruction of the joint. It can be performed as gap arthroplasty (creating a gap between the bones) or interpositional arthroplasty (placing a material between the joint surfaces).
- Osteotomy: In cases of severe deformity, osteotomy may be performed to realign the jaw.
- TMJ Replacement: In severe cases, a total joint replacement may be necessary.
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Postoperative Care:
- Physical Therapy: Post-surgical rehabilitation is crucial to restore function and improve range of motion. Exercises may include gentle stretching and strengthening of the jaw muscles.
- Pain Management: Analgesics and anti-inflammatory medications may be prescribed to manage postoperative pain.
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Long-term Management:
- Regular Follow-up: Patients require ongoing monitoring to assess joint function and detect any recurrence of ankylosis.
- Oral Hygiene: Maintaining good oral hygiene is essential, especially if mouth opening is limited.
Prognosis
The prognosis for patients with TMJ ankylosis varies depending on the severity of the condition, the type of surgical intervention performed, and the patient's adherence to postoperative rehabilitation. Many patients experience significant improvement in jaw function and quality of life following appropriate treatment.
Frenectomy- Overview and Techniques
A frenectomy is a surgical procedure that involves the removal of a frenum, which is a thin band of fibrous tissue that connects the lip or tongue to the underlying alveolar mucosa. This procedure is often performed to address issues related to abnormal frenal attachments that can cause functional or aesthetic problems.
Key Features of Frenal Attachment
- A frenum consists of a thin band of fibrous tissue and a few muscle fibers, covered by mucous membrane. It serves to anchor the lip or tongue to the underlying structures.
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Common Locations:
- Maxillary Midline Frenum: The most commonly encountered frenum, located between the central incisors in the upper jaw.
- Lingual Frenum: Found under the tongue; its attachment can vary in length and thickness among individuals.
- Maxillary and Mandibular Frena: These can also be present in the premolar and molar areas, potentially affecting oral function and hygiene.
Indications for Frenectomy
- Functional Issues: An overly tight or thick frenum can restrict movement of the lip or tongue, leading to difficulties in speech, eating, or oral hygiene.
- Aesthetic Concerns: Prominent frena can cause spacing issues between teeth or affect the appearance of the smile.
- Orthodontic Considerations: In some cases, frenectomy may be performed prior to orthodontic treatment to facilitate tooth movement and prevent relapse.
Surgical Techniques
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Z-Plasty Procedure:
- Indication: Used when the frenum is broad and the vestibule (the space between the lip and the gums) is short.
- Technique: This method involves creating a Z-shaped incision that allows for the repositioning of the tissue, effectively lengthening the vestibule and improving the functional outcome.
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V-Y Incision:
- Indication: Employed for lengthening a localized area, particularly when the frenum is causing tension or restriction.
- Technique: A V-shaped incision is made, and the tissue is then sutured in a Y configuration, which helps to lengthen the frenum and improve mobility.
Postoperative Care
- Pain Management: Patients may experience discomfort following the procedure, which can be managed with analgesics.
- Oral Hygiene: Maintaining good oral hygiene is crucial to prevent infection at the surgical site.