Most cysts are discovered as a chance finding on routine dental radiography. On an x-ray, cysts appear as radiolucent (dark) areas with radiopaque (white) borders. Cysts are usually unilocular, but may also be multilocular. Sometimes aspiration is used to aid diagnosis of a cystic lesion, e.g. fluid aspirate from a radicular cyst may appear straw colored and display shimmering due to cholesterol content. Almost always, the cyst lining is sent to a pathologist for histopathologic examination after it has been surgically removed. This means that the exact diagnosis of the type of cyst is often made in retrospect.

A non-vital tooth is necessary for the diagnosis of a periapical cyst, meaning the nerve has been removed by root canal therapy. Oral examination of the surrounding intraoral anatomical structures should be palpated to identify the presence of bone expansion or displacement of tooth roots as well as crepitus noises during examination, indicating extensive bone damage. Bulging of the buccal or lingual cortical plates may be present. Age of occurrence in the patient, the location of the cyst, the edges of cystic contours, and the impact that the cyst has on adjacent structures must all be considered for proper diagnosis.

Several lesions can appear similarly in radiographic appearance. Intraoral X-rays or a 3-D cone beam scan of the affected area can be used to obtain radiological images and confirm diagnosis of cysts in the periapical area. Circular or ovoid radiolucency surrounding the root tip of approximately 1-1.5 cm in diameter is indicative of the presence of a periapical cyst. The border of the cyst is seen as a narrow opaque margin contiguous with the lamina dura. In cysts that are actively enlarging, peripheral areas of the margin may not be present. Periapical cysts have a characteristic unilocular shape on radiographs. There is also a severe border of cortication between the cyst and surrounding bone. Pseudocysts, on the other hand, have a fluid filled cavity but are not lined by epithelium, therefore they have a less severe and more blurred border between the fluid and bony surroundings.

Resorption of the roots of affected teeth may also be observed as the absence of portions of normal root structures.

Infected cysts will produce a positive percussion test on the affected tooth as well as a negative response to the pulp test. There may also be visible swelling in the overlying soft tissues. The affected tooth may also exhibit discoloration.

a nuclear imaging method to evaluate any degenerative and/or arthritic changes in the joints; to detect bone diseases and tumors; to determine the cause of bone pain or inflammation. This test is to rule out other cysts (which are quite unusual)

The prognosis depends upon the type, size and location of a cyst. Most cysts are entirely benign, and some may require no treatment. Rarely, some cystic lesions represent locally aggressive tumors that may cause destruction of surrounding bone if left untreated. This type of cyst are usually removed with a margin of healthy bone to prevent recurrence of new cysts. If a cyst expands to a very large size, the mandible may be weakened such that a pathologic fracture occurs.

Epidermoid cysts are usually diagnosed when a person notices a bump on their skin and seeks medical attention. The definitive diagnosis is made after excision by a pathologist based on microscopic appearance of a cystic lesion lined by cornified epithelium containing lamellated keratin without calcifications. They can also be seen as isointense lesions on MRI or hyperintensities on FLAIR.

No treatment is required, but neoplastic processes (metastatic maliganancy to the submandibular lymph nodes and/or salivary gland tumours) should be ruled out. This is usually done with clinical exam and imaging. Very rarely, since the defect contains salivary gland tissue, salivary gland tumors can occur within an established defect but there is likely no difference in the risk of neoplasia in salivary gland tissue at other sites.

CT scans use x-rays and computer technology to produce accurate axial, coronal, and sagittal images. CT scans are more detailed than x-rays because they can create images that show fat, muscles, organs, and bones.

Treatment ranges from simple enucleation of the cyst to curettage to resection. For example, small radicular cyst may resolved after successful endodontic ("root-canal") treatment. Because of high recurrence potential and aggressive behaviour, curettage is recommended for keratocyst. However, the conservative enucleation is the treatment of choice for most odontogenic cysts. The removed cyst must be evaluated by pathologist to confirm the diagnosis, and to rule out other neoplastic lesions with similar clinical or radiographic features (e.g., cystic or solid ameloblastoma, central mucoepidermoid carcinoma). There are cysts, e.g. buccal bifurcation cyst with self-resolation nature, in which close observation can be employed unless the cyst is infected and symptomatic.

Stafne's defect is usually discovered by chance during routine dental radiography. Radiographically, it is a well-circumscribed, monolocular, round, radiolucent defect, 1–3 cm in size, usually between the inferior alveolar nerve (IAN) and the inferior border of the posterior mandible between the molars and the angle of the jaw. It is one of the few radiolucent lesions that can occur below the IAN. The border is well corticated and it will have no effect on the surrounding structures. Computed tomography (CT) will show a shallow defect through the medial cortex of the mandible with a corticated rim and no soft tissue abnormalities, with the exception of a portion of the submandibular gland. Neoplasms, such as metastatic squamous cell carcinoma to the submandibular lymph nodes or a salivary gland tumour, could create a similar appearance but rarely have such well defined borders and can usually be palpated in the floor of the mouth or submandibular triangle of the neck as a hard mass. CT and clinical exam is typically sufficient to distinguish between this and a Stafne defect. The Stafne defect also tends to not increase in size or change in radiographic appearance over time (hence the term "static bone cyst"), and this can be used to help confirm the diagnosis. Tissue biopsy is not usually indicated, but if carried out, the histopathologic appearance is usually normal salivary gland tissue. Sometimes attempted biopsy of Stafne defects reveals an empty cavity (possibly because the gland was displaced at the time of biopsy), or other contents such as blood vessels, fat, lymphoid or connective tissues. Defects of the anterior lingual mandible may require biopsy for correct diagnosis at this unusual location. The radiolucent defect here may be superimposed on the lower anterior teeth and be mistaken for an odontogenic lesion. Sometimes the defect may interrupt the contour of the lower border of the mandible, and may be palpable. Sialography may be sometimes used to help demonstrate the salivary gland tissue within the bone.

Nabers probe is used to check for furcation involvement clinically. Recently, cone beam computerised technology (CBCT) has also be used to detect furcation. Periapical and interproximal intraoral radiographs can help diagnosing and locating the furcation. The location and severity of furcation should be recorded in patient’s notes.

Only multirooted teeth have furcation. Therefore, upper first premolar, maxillary and mandibular molars may be involved.

Upper premolars have one buccal and one palatal root. Furcation involvement should be checked from the mesial and the distal aspects of the tooth.

Maxillary molars have three roots, a mesio-buccal root, disto-buccal root and a palatal root. Thus, check for furcation from buccal, mesio-palatal and disto-palatal aspects.

Mandibular molars have one mesial and one distal root, and so, check for involvement from buccal and lingual aspects.

Nasopalatine duct cysts usually present as asymptomatic palatal swellings, but they may rarely be accompanied by pain and/or purulent discharge. The cysts are generally treated by .

A dentigerous cyst or follicular cyst is an odontogenic cyst - thought to be of developmental origin - associated with the crown of an unerupted (or partially erupted) tooth. The cyst cavity is lined by epithelial cells derived from the reduced enamel epithelium of the tooth forming organ. Regarding its pathogenesis, it has been suggested that the pressure exerted by an erupting tooth on the follicle may obstruct venous flow inducing accumulation of exudate between the reduced enamel epithelium and the tooth crown.

In addition to the developmental origin, some authors have suggested that periapical inflammation of non-vital deciduous teeth in proximity to the follicles of unerupted permanent successors may be a factor for triggering this type of cyst formation.

Histologically a normal dental follicle is lined by enamel epithelium, whereas a dentigerous cyst is lined by non-keratinized stratified squamous epithelium. Since the dentigerous cyst develops from follicular epithelium it has more potential for growth, differentiation and degeneration than a radicular cyst. Occasionally the wall of a dentigerous cyst may give rise to a more ominous mucoepidermoid carcinoma. Due to the tendency for dentigerous cysts to expand rapidly, they may cause pathological fractures of jaw bones.

On Fine needle aspiration, thin straw colored fluid is seen.

The usual radiographic appearance is that of a well-demarcated radiolucent lesion attached at an acute angle to the cervical area of an unerupted tooth. The border of the lesion may be radiopaque. The radiographic differentiation between a dentigerous cyst and a normal dental follicle is based merely on size. Radiographically, a dentigerous cyst should always be differentiated from a normal dental follicle. Dentigerous cysts are the most common cysts with this radiographic appearance. Radiographically the cyst appears unilocular with well defined margins and often sclerotic borders but sometimes it may be multilocular in appearance and may also have a continuous cystic membrane. Infected cysts show ill-defined margins. Follicular space more than 3mm is to be considered a dentigerous cyst.

Radiographically there are three types of dentigerous cyst, namely the Central type, Lateral type and the Circumferential type.

The most common location of dentigerous cysts are the Mandibular 3rd Molars and the Maxillary Canines, and they rarely involve deciduous teeth and are occasionally associated with odontomas.

A dentigerous cyst is often treated by excision of the cyst along with the extraction of the associated tooth.

In case of a large cyst marsupialization is done.

The standard treatment of COC is enucleation and curettage (E&C). Recurrence following E&C is rare.

The infected tissue of the periapical cyst must be entirely removed, including the epithelium of the cyst wall; otherwise a relapse is likely to occur. Root canal treatment should be performed on the tooth if it is determined that previous therapy was unsuccessful. Removal of the necrotic pulp and the inflamed tissue as well as proper sealing of the canals and an appropriately fitting crown will allow the tooth to heal under uninfected conditions.

Surgical options for previously treated teeth that would not benefit from root canal therapy include cystectomy and cystostomy. This route of treatment is recommended upon discovery of the cyst after inadequate root canal treatment. A cystectomy is the removal of a cyst followed by mucosa and wound closure to reduce chances of cyst regeneration. This type of treatment is more ideal for small cysts.

A cystostomy is recommended for larger cysts that compromise important adjacent anatomy. The cyst is tamponaded to allow for the cyst contents to escape the bone. Over time, the cyst decreases in size and bone regenerates in the cavity space.

Marsupialization could also be performed, which involves suturing the edges of the gingiva surrounding the cyst to remain open. The cyst then drains its contents and heal without being prematurely closed. The end result is the same as the cystostomy, bone regeneration. For both a cystostomy and marsupialization, root resectioning may also be required in cases where root resorption has occurred.

Sebaceous cysts generally do not require medical treatment. However, if they continue to grow, they may become unsightly, painful, infected, or all of the above.

Diagnosis of a thyroglossal duct cyst requires a medical professional, and is usually done by a physical examination. It is important to identify whether or not the thyroglossal cyst contains any thyroid tissue, as it can define the degree of cyst that is being dealt with.

Diagnostic procedures for a thyroglossal cyst include:

Clinical features can be found in the subhyoid portion of the tract and 75% present as midline swellings. The remainder can be found as far lateral as the lateral tip of the hyoid bone.

Typically, the cyst will move upwards on protrusion of the tongue, given its attachment to the embryonic duct, as well as on swallowing, due to attachment of the tract to the foramen caecum.

Cysts can be removed by excision.

In case of fronto-ethmoidal epidermoid cysts, surgical resection appears to be the mainstay of treatment; however, the extent of resection is dictated by adherence of the tumor capsule to the surrounding vital structures.

Hydrogen peroxide gel (HO) was previously recommended for cyst treatment, particularly those on body piercings. However the gel cannot adequately permeate the cyst and was not found to be effective. Hydrogen peroxide is no longer recommended for wound care by doctors as it can damage the healing tissues.

On body piercings, self treatment with a hot saline soak to help drain the cyst and the use of an antibacterial or medicated talcum powder (Use of talc is no longer recommended due to recently discovered associations with multiple cancers.) to help dry out the bump and reduce bacterial proliferation is generally recommended until medical advice can be obtained. Piercings, however, are more likely to be victims of hypertrophic scarring than a cyst. Cheek piercings seem to be the piercing most prone to cysts due to the possible interruption of saliva ducts.

Recurrence rate of solid form of tumour is lower than classic form.

Surgical excision of the lesion is done, and depending upon the clinical circumstances, this may or may not involve removal of the involved tooth. With incomplete removal, recurrence is common; some surgeons advocate curettage after extraction of teeth to decrease the overall rate of recurrence.

Surgical excision of a sebaceous cyst is a simple procedure to completely remove the sac and its contents.

There are three general approaches used: traditional wide excision, minimal excision, and punch biopsy excision.

The typical outpatient surgical procedure for cyst removal is to numb the area around the cyst with a local anaesthetic, then to use a scalpel to open the lesion with either a single cut down the center of the swelling, or an oval cut on both sides of the centerpoint. If the cyst is small, it may be lanced instead. The person performing the surgery will squeeze out the keratin surrounding the cyst, then use blunt-headed scissors or another instrument to hold the incision wide open while using fingers or forceps to try to remove the cyst intact. If the cyst can be removed in one piece, the "cure rate" is 100%. If, however, it is fragmented and cannot be entirely recovered, the operator may use curettage (scraping) to remove the remaining exposed fragments, then burn them with an electro-cauterization tool, in an effort to destroy them in place. In such cases the cyst may recur. In either case, the incision is then disinfected and, if necessary, the skin is stitched back together over it. A scar will most likely result.

An infected cyst may require oral antibiotics or other treatment before or after excision. If pus has already formed then incision and drainage should be done along with avulsion of cyst wall with proper antibiotics coverage.

An approach involving incision, rather than excision, has also been proposed.

A pilonidal cyst can resemble a dermoid cyst, a kind of teratoma (germ cell tumor). In particular, a pilonidal cyst in the gluteal cleft can resemble a sacrococcygeal teratoma. Correct diagnosis is important because all teratomas require complete surgical excision, if possible without any spillage, and consultation with an oncologist.

Ganglion cysts are diagnosed easily, as they are visible and pliable to touch.

Radiographs in AP and lateral views should be obtained to exclude any more serious underlying pathology. Ultrasonography (US) may be used to increase diagnostic confidence in clinically suspected lesions or to depict cysts, because intratendinous ganglia are readily distinguished from extratendinous ganglia during dynamic ultrasonography, as microscopically, ganglionic cysts are thin-walled cysts containing clear, mucinous fluid.

Small unilocular lesions have been successfully treated with enucleation and curettage followed by chemical bone cautery. Multilocular tumors exhibit a 25% recurrence rate and, therefore, must be treated more aggressively. In the case of a multilocular myxoma, resection of the tumor with a generous portion of surrounding bone is required. Because of the gelatinous nature of the tumor, it is crucial for the surgeon to remove the lesion intact so as to further reduce the risk of recurrence.

Unilocular radiolucency may be seen and mutilocular also, and mixed too .irregular calcifications may be seen in some cases.