Maxillofacial Surgery
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BIOPSIES
Biopsies are usually performed to undertake microscopic examination of a lesion for diagnostic purposes. Any lesions that persist for more than 14 days despite the removal/absence of a potential irritant should be investigated. In the case of FNA, CT or ultrasound can be used to guide the clinician to the correct tissue.
For incisional and excisional biopsies, a sharp scalpel blade will modify the tissue sample the least. A surgical site is designed for optimal closure and healing. You should avoid injection of local anesthesia directly into the lesion (would cause distortion). Proper specimen processing requires that the tissue be placed in 10% formalin (4% formaldehyde) in a volume at least 20 times that of the tissue removed. The tissue sample should be fully submerged and not stuck to the sides of the container.
- Incisional – removes a representative proportion of a highly suspicious lesion and includes normal tissue. Used for larger lesions that may be difficult to remove because of size or hazardous location.
- Excisional – removed the entire lesion, usually with at least 2mm normal tissue margin. Can double as treatment. Often used for lesions less than 1cm that are thought to be benign.
- Aspiration – use of a needle to sample the contents of a lesion. Final needle aspiration (FNA).
- Punch – often used for full thickness skin specimens using a 3-4mm diameter circular blade.
- Frozen section – or cryosection, usually not as good as formalin fixed tissue processing.
- Exfoliative – not a substitute for a conventional biopsy but can be used as an early detection/screening system for malignant tumors (Pap smear/test).
- Brush biopsy – scraping away, similar to exfoliative.
Oral ulcers are relatively common and usually caused by trauma, healing within 2 weeks. Any ulcer that lasts longer than 2 weeks should be biopsied. A biopsy should be considered for pigmented lesions, or lesions that enlarge suddenly. Aspiration of a central bony lesion is used to rule out vascular lesions.
ORAL EXOSTOSES (TORI)
Also known as exostoses, tori (singular: torus, exostosis) are benign bony outgrowths most often found in the center line of the palate and lingual surface of the body of the mandible. Usually unremarkable, tori may interfere with speech, trap food, impede prostheses, and can lead to ulceration from trauma to thin overlying mucosa. Removal is simple and can be done under local or general anesthesia. It should not be removed en masse to prevent entry into the nasal cavity. Tori are usually segmented and removed (a chisel/osteotome is useful). A stent is usually fabricated for palatal tori and inserted after the removal to support the flap and prevent hematoma formation.
SIALOLITHIASIS
A siololith is a calcificied mass that forms in the salivary gland or duct. The submandibular gland (and Wharton’s duct) is the most commonly affected (85%), then the parotid, sublingual, and minor salivary glands. Signs and symptoms include erythema, pain and swelling of the affected gland and duct, mosty around meal time when salivary flow is stimulated.
A full blockage will prevent salivary flow. Purulent discharge and lymphadenopathy may be seen if the area becomes infected. Infections, dehydration, Sjogren’s syndrome, foreign bodies, and high levels of calcium can contribute to siololith formation. Small stones may be helped out by increasing salivary flow or masaged free. Sialoendoscopy (small endoscope) can be used. Surgical removal is generally curative, though with persistent calculus formation removal of the entire gland may be necessary.
Recall the parotid glands are the largest major salivary gland, entirely serous in secretion, and drains via the Stenson duct which crosses from the anterior border of the masseter muscle and pierces the buccinator muscle around the maxillary second molar.
The von Ebner glands are also purely serous. The submandibular glands drains via the Wharton duct which travels along the floor of the mouth, over the sublingual glands. It is a mixed (serous and mucous) gland, predominantly mucous. The submandibular glands wrap around the posterior surface of the mylohyoid muscle. The sublingual glands sit superior to the mylohyoid muscle and is a mixed salivary gland, predominantly secreting mucus. It is connected to many small (Rivian) ducts, which occasionally fuse to form a single main excretory (Bartholin’s) duct.
CLEFT LIP AND PALATE
Cleft lip (CL) and Cleft Palate (CP) are the most common craniofacial defects (1/700 births) resulting from a failure in fusion of the frontonasal (medial nasal) process and maxillary process in the first trimester around 5-8 weeks in utero (CL 5-6 weeks, CP 6-8 weeks).
Remember the first branchial arch (mandibular arch) gives rise to the maxilla, mandible, Meckel’s cartilage, incus, malleus, muscles of mastication and the anterior belly of the digastric muscle.
CL and CP accounts for half of all facial cleft defects, CL is more common in males and more often seen unilaterally on the left side. CP is more common in females. The fusion of the lip, alveolar ridge, and palate can be involved, affecting speech, feeding, swallowing and aesthetics. CL & CP can occur unilaterally, often a birth defect that isn’t associated with a syndrome, or bilaterally, linked to Stickler’s, Vander Woude’s, and DiGeorge syndrome. There are four classes of CL:
- Class I: Unilateral notching of vermillion not extending to the lip.
- Class II: Class I but involving the lip, not to the floor of the nose.
- Class III: Class II but extending into the floor of the nose.
- Class IV: Any bilateral cleft of the lip.
There are four classes of CP
- Class I: only the soft palate is involved.
- Class II: the soft palate and hard palate are involved, but not the alveolar processes.
- Class III: the soft palate, hard palate and alveolar process on one side of the premaxilla.
- Class IV: the soft palate, hard palate and alveolar process on both sides of the premaxilla.
Unrepaired cleft lip comes with significant social stigma. CL is repaired 10 weeks after birth, CP 9-18 months after birth. CL is reviewed around age 5. Then another pharyngeal flap surgery or pharyngoplasty 3-5 years later, alveolar reconstruction at 6-9 years (based on dental development), and orthognathic surgery at 14-18 years (14-16 for girls, 16-18 for boys).
CYSTS AND TUMORS
The goal of treatment would be to accurately diagnose and remove the pathology, then reestablish form, function and esthetics.
Odontogenic keratocysts tend to be more aggressive and have higher rates of recurrence than other fissural or odontogenic cysts.
Recall neoplasia nomenclature:
- Carcinoma – malignant neoplasm of epithelial origin.
- Sarcoma – tumor from supportive and connective tissues such as bone, tendons, cartilage, muscles and fat.
- Myeloma – neoplasm that originates from plasma cells of bone marrow.
- Leukemia – cancers of the bone marrow, often producing immature white blood cells.
- Lymphoma – neoplasm from lymph glands, lymph nodes, lymph vessels or lymph organs. Lymphomas are subclassified as either Hodgkin lymphoma (Reed-Sternberg cells present) or Non-Hodgkin lymphoma.
A neoplasm could contain cellular contents from more than one source.
SURGICAL TREATMENT
Cysts and cyst-like lesions are commonly treated by either enucleation, marsupialization, or surgical removal. Tumors will show great variation in origin, size, anatomical location, duration, clinical behavior, and response to treatment. Based on these factors, enucleation, curettage, resection, chemotherapy or radiotherapy may be selected.
Enucleation involves shelling out the lesion without it rupturing, removing the entire cyst. A full thickness mucoperiosteal flap is raised, bone removed as necessary, and the entire cyst is extracted. The wound can be packed, and the margins sutured.
Enucleation does not sacrifice surrounding structures and can be combined with curettage, the removal of the cyst as well as some (1-2mm) surrounding bone which may contain remnants of the cystic cellular lining. This is preferred for lesions like odontogenic keratocysts which have a tendency to recur after enucleation.
Marsupialization involves creating a surgical window into the wall of the cystic lesion, followed by decompression and evacuation of the cyst contents. This window is often left open which allows the cyst to shrink and for bony infill. The window is usually prevented from closing with some sort of plug.
Marsupialization is preferred when enucleation would damage adjacent structures. It is however an open lesion that needs extra care (at home oral care, monitoring). Marsupialization may be used with dentigerous cysts to avoid tooth extraction.
The two treatment options are sometimes combined, marsupialization followed by a second enucleation procedure. Enucleation and/or curettage is suggested for most odontogenic tumors. Resection is reserved for invasive tumors with a tendency to recur.
Resection can be classified as:
- Marginal – resection of a tumor without the disruption of the continuity of the bone. In mandibular surgery, the teeth, alveolar bone and body may be removed, leaving the inferior border of the mandible. The lost bone is reconstructed.
- Partial thickness – resection of a full thickness portion of the jaw. Can vary from a small section to hemimandibulectomy. Jaw continuity is disrupted.
- Total – removing all the involved bone e.g maxillectomy or mandibulectomy.
- Composite – resection of the tumor with bone, adjacent soft tissues, and contiguous lymph nodes. Composite resections are most commonly used with malignant tumors. Significant functional and cosmetic loss. Usually involves neck dissection.
Marginal or partial resection is recommended for Ameloblastoma, Calcifying epithelial odontogenic tumor, Myxoma, Ameloblastic odontoma, Squamous odontogenic tumor, Benign fibroma, and Hemangioma.
Composite resection is recommended for Malignant ameloblastoma, Ameloblastic fibrosarcoma, Ameloblastic odontosarcoma, Primary intraosseous carcinoma, Fibrosarcoma, Osteosarcoma, Chondrosarcoma, Ewing’s sarcoma, Lymphomas, Intraosseous salivary gland malignancies, Neurofibrosarcoma, and Carcinoma that involves the jaw.
