Classification of cysts by origin
All maxillofacial cysts are broadly divided into two major groups depending on the source of epithelial formation:
1. Odontogenic (tooth-related)
- Radicular (periapical) — the absolute leader in frequency.
- Follicular — develop from the follicle of an unerupted tooth.
- Tooth-containing.
- Subperiosteal.
- Residual.
2. Non-odontogenic (not related to tooth formation) These include lesions arising from the remnants of embryonic ducts and clefts:
- Nasopalatine (incisive canal cysts);
- Globulomaxillary;
- Nasoalveolar (nasolabial);
- Primary (keratocysts);
- Eruption cysts.
Pathogenesis of radicular cyst
A radicular cyst forms against the background of chronic inflammation, most often in granulomatous periodontitis. This process consists of a clear sequence of stages:
- Formation of the fibrous capsule. Frequent exacerbations of inflammation and impaired local blood flow in the granuloma attract fibroblasts. They actively synthesize collagen, surrounding the granuloma with a dense fibrous capsule.
- Epithelialization. In the remission phase, epithelium proliferates inside the formed capsule, gradually replacing the granulation tissue.
- Formation of the lining. Epithelial islands merge to form a continuous inner layer of the capsule.
- Accumulation of secretion. Epithelial cells begin to produce fluid. Initially, a transitional form arises — cystogranuloma, which transforms into a full-fledged radicular cyst as fluid accumulates.
- Increase in size. Growth is slow. Intracystic hydrostatic pressure becomes higher than intraosseous pressure.
- Bone resorption. Due to constant pressure, the surrounding bone tissue atrophies.
- Subperiosteal transformation. If the bone thins until a defect forms, the lesion continues to grow underneath the periosteum.
Pathomorphology and clinical presentation
The wall of the formed cyst consists of dense connective tissue on the outside and an epithelial lining on the inside (usually stratified squamous non-keratinizing epithelium). Due to periodic inflammation, part of the epithelium may undergo necrosis, which is why it is often detected only focally upon histology. A characteristic marker is the presence of cholesterol, formed during the breakdown of lipid-containing cells.
Clinical manifestations directly depend on the size:
- Small cysts are asymptomatic and become an accidental radiographic finding.
- Lesions larger than 3 cm cause dental arch deformation and bulging of the jaw wall.
Specific symptoms are determined by localization. In the mandible, compression of the neurovascular bundle can provoke Vincent's sign — paresthesia (numbness) of the lower lip. When the lesion grows from the maxilla towards the piriform aperture, a specific protrusion forms in the inferior nasal meatus — Gerber's ridge.
Suppuration of the cyst drastically changes the clinical picture: intoxication and pain appear, and complications develop in the form of periostitis, osteomyelitis, or sinusitis.
Relationship with the maxillary sinus
The anatomical proximity of the roots of maxillary premolars and molars to the maxillary sinus leads to its frequent involvement in the process. The growing cyst gradually thins the bony partition. Three scenarios are possible:
- The lesion simply abuts the unaltered floor of the sinus.
- The sinus floor is displaced: the bone thins and domes into the sinus.
- The cyst penetrates into the sinus: the bony septum completely disappears. A domelike soft tissue shadow is visible on the radiograph, and the sinus itself is reduced to a slit-like space.
Briefly: answers to topical questions
What radiographic features are characteristic of a radicular cyst of the jaw?
A radicular cyst of the jaw is characterized by specific radiographic manifestations depending on its localization and effect on surrounding tissues. When growing in the area of the upper lateral incisor, the root is separated from the palate by a thin plate, and the cyst grows toward the palate. In the region of premolars and molars, it often grows toward the maxillary sinus. Ingrowth into the sinus leads to deformation and disappearance of the bone layer: the cyst may abut the sinus, displace its floor with thinning and domelike displacement of the bony wall, or penetrate inward with the formation of a domelike soft tissue shadow against the background of the sinus, which turns into a slit-like space.
How does a follicular cyst differ from a radicular one?
A follicular cyst differs from a radicular one in its origin, source of formation, and radiographic picture. It develops from the dental sac or enamel organ of an unerupted tooth as a result of a disturbance in dental bud development. While a radicular cyst is associated with a chronic inflammatory process around the root of the tooth, the lining of a follicular cyst attaches strictly at the cementoenamel junction of the causative tooth. On the radiograph of a follicular cyst, the crown of the unerupted tooth is clearly determined within the cavity, and the root of the tooth is always located outside the cyst.
What surgical treatment methods are used for jaw cysts?
Treatment of jaw cysts is surgical and includes two main types of surgical intervention. The first method is cystectomy — a surgical procedure consisting of the complete radical removal of the cyst lining followed by primary closure of the surgical wound. This method is used primarily for cysts whose size does not exceed 3 cm. The second main method is cystotomy, in which the cystic cavity is communicated with the oral vestibule, turning it into an accessory cavity in the mouth. Cystotomy is indicated for large maxillary cysts growing into the maxillary sinus, extensive mandibular cysts with the threat of a pathological fracture, as well as in mixed dentition.
From which specific embryonic structures do globulomaxillary cysts form?
The provided educational materials lack information on the specific embryonic structures from which globulomaxillary cysts form. The text only indicates that non-odontogenic cysts and fissural cysts are associated with impaired facial embryogenesis.
To easily remember the groups of odontogenic cysts, use the mnemonic: Radicular, Follicular, Tooth-containing, Subperiosteal, Residual.
Class and exam questions
What is Gerber's ridge?
This is a characteristic bulge in the inferior nasal meatus, which is identified during rhinoscopy if the maxillary cyst grows toward the pyriform aperture.
Why does cholesterol form inside a radicular cyst?
Cholesterol crystals appear as a result of the breakdown of lipid-rich cellular structures against the background of a chronic inflammatory process.
What happens to bone tissue as the lesion grows?
The pressure of the intracystic fluid exceeds intraosseous pressure. This constant mechanical impact leads to atrophy of the surrounding bone tissue.
What else to study on this topic
- Histological variants of the epithelial lining structure (columnar, ciliated epithelium).
- Differential diagnosis of a radicular cyst and a cystogranuloma.
- Features of the clinical oral examination when a cyst is localized on the palate.
- Surgical tactics for suppuration and the development of sinusitis.
- Manifestations and diagnosis of the subperiosteal form of a cyst.
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