Why Is BSSO Considered a Standardized Technique in Orthognathic Surgery?
Orthognathic surgery is a vast field in modern-day dentistry and oral surgery that primarily involves the surgical correction of the components of the facial skeleton. This is to restore the proper anatomy as well as functionality in all dental patients with dentofacial (refers to both the dental and facial structures, implying a connection or relationship between the teeth and the face) or skeletal abnormalities. The bilateral sagittal split osteotomy is a major surgery used frequently by oral surgeons in the correction of most dentofacial abnormalities. This technique has its roots and has been in practice ever since the late 1800s. However, it did not reach acceptance amongst many oral surgeons in the past until several modern-day modifications were suggested in the 1960s and 1970s. Changes made to a common dental procedure called the sagittal split osteotomy have been recognized as the best way to correct issues with the teeth and jaw. These changes are known as BSSO, which stands for bilateral sagittal split osteotomy. With modern improvements in dental tools and techniques, this updated procedure is now considered a much safer and reliable choice. It can help prevent dental and facial problems from coming back and fix issues like crooked teeth or improper bites.
What Are the Indications of BSSO?
Bilateral sagittal split osteotomy (BSSO) is frequently recommended or preferred for correcting issues with the mandible, or lower jaw, in patients. This procedure may be conducted alone or in conjunction with upper jaw surgery. Major indications for BSSO include:
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Excess horizontal or mandibular or lower jaw protrusion.
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Deficiency in the mandibular or lower jaw structure.
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Severe facial asymmetry.
Moreover, BSSO, known as mandibular advancement, remains a popular choice for advancing the lower jaw. Surgeons utilize this technique to achieve mild to moderate corrections in lower jaw deformities.
What Are the Factors Influencing Surgical Outcomes of the BSSO Technique?
When considering the implementation of BSSO for an individual patient, there are several factors that the surgeon will take into account for recommending or performing modifications. These factors may include the position of the mandibular foramen, which is crucial for jaw sensations due to the course of the lingual nerve, and the path of the inferior alveolar nerve in the mandible. Additionally, the presence of lower or mandibular third molars, if any, and the direction and extent of movement required for the distal segments during surgery are also important considerations.
Furthermore, other factors influencing the decision to modify BSSO for a patient include the overall facial aesthetics, occlusal relationships, airway considerations, and the presence of any pre-existing dental or skeletal abnormalities. The surgeon will also assess the patient's medical history, dental health, and any potential risks associated with the procedure. Additionally, patient preferences and expectations play a significant role in tailoring the surgical approach to ensure optimal outcomes and patient satisfaction.
What Are the Steps of BSSO Performed by the Oral and Maxillofacial Surgeon?
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The patient is firstly placed in a supine position (refers to lying flat on one's back with the face and torso facing upward) on the operating table.
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The nasotracheal intubation (a medical procedure in which a breathing tube is inserted through the nostril and advanced into the trachea to establish an airway for mechanical ventilation) is usually performed first and the patient is prepared by the surgeon after draping for the intraoral procedure.
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The surgeon must have a clear visual or broad vision of the entire face and neck within the operating field. The Bilateral inferior alveolar nerve blocks are administered by the dentist or the oral surgeon using a short-acting local anesthetic and vasoconstrictor (a substance or agent that causes the constriction or narrowing of blood vessels, leading to a decrease in blood flow to the affected area).
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These anesthetics can be further supplemented by using a long-acting anesthetic toward the end of the procedure, which can also aid in effective pain management for the patient.
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The bilateral inferior alveolar nerve blocks are infiltrated into the submucosa anteriorly in the segments of the buccal vestibule in the oral cavity and along the ascending ramus in the jaw.
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Intraoral landmarks that need to be identified by the surgeon clearly for giving the intraoral incisions are the anterior border of the mandibular or lower jaw ramus and the external oblique ridge.
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The oral and maxillofacial surgeon or dental operator usually takes the utmost care to maintain the level of surgical dissection subperiosteally (refers to a surgical technique or maneuver that occurs beneath the periosteum, which is the dense fibrous membrane covering the surface of bones)
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Adequate retraction is done during surgery to prevent soft tissue damage prevent minor intraoperative hemorrhages (refer to the escape of blood from a ruptured blood vessel, leading to bleeding either internally or externally) that can be controlled usually by using methods of electrocautery, pressure, or specific vasoconstrictive agents.
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The tissue mucosa is usually incised using the electrocautery and the approach would be to the inferior and lateral part of the external oblique ridge, which continues laterally usually into the vestibule of the first molar. The mandible is placed in its desired position during the osteotomy (a surgical procedure involving the cutting or reshaping of bone tissue) procedure and takes the aid of a prefabricated splint usually.
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The two segments of the lower jaw are fixated according to the surgeon's preference on either of the lower jaw sides using commonly a miniplate with three holes at the osteotomy. During the placement of the fixation, it is ensured that the lower condyle remains well established within the fossa.
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Once the inner segments are thoroughly ensured that they are well-fixed, the patient's occlusion is checked and should be deemed satisfactory by the operator or surgeon.
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The incisions are then subsequently closed with absorbable sutures after performing a irrigation and achieving effective hemostasis (a process by which bleeding is stopped or controlled, usually through the constriction of blood vessels, and the formation of blood clots).
What Precautions Should the Operator Take to Avoid Postoperative Complications?
Care should be taken by the surgeon to prevent complications associated with BSSO, such as bleeding from injury to the inferior alveolar or masseteric arteries, jaw fractures, and avascular necrosis (refers to the death of bone tissue due to a lack of blood supply, leading to the deterioration and collapse of the affected bone). Specific attention should be paid to the positioning of proximal segments to avoid such complications, especially in individuals with a history of temporomandibular joint (TMJ) issues.
Furthermore, the surgeon must exercise caution to minimize the risk of injury to the inferior alveolar nerve. The incidence of nerve transection (refers to the complete severing or cutting of a nerve, leading to loss of its function) is typically reported to be between two to three percent in patients, with long-term neurologic deficits (impairments or abnormalities in the functioning of the nervous system, which can include sensory, motor, or cognitive functions) or alterations in jaw sensation occurring in ten to thirty percent of cases. However, with advancements in screw fixation techniques, postoperative complications related to lingual nerve injuries have declined over the years. Currently, the risk of lingual nerve injury following BSSO is considered a very uncommon complication.
Conclusion:
In conclusion, the modernized version of the common orthognathic jaw surgery procedure, bilateral sagittal split osteotomy (BSSO), remains the gold standard for correcting most dentofacial and mandibular deformities. Dental or maxillofacial surgeons must begin with a comprehensive assessment of the patient's dental and medical history. Moreover, addressing dentofacial deformities, particularly those affecting the lower jaw, demands a practitioner's thorough understanding. This includes familiarity with the indications, contraindications, and common post-surgical complications associated with BSSO.
