Periapical cysts begin as asymptomatic and progress slowly. Subsequent infection of the cyst causes swelling and pain. Initially, the cyst swells to a round hard protrusion, but later on the body resorbs some of the cyst wall, leaving a softer accumulation of fluid underneath the mucous membrane.

Larger cysts may cause bone expansion or displace roots. Discoloration of the affected tooth may also occur. Patient will present negative results to electric and ice test of the affected tooth but will be sensitive to percussion. Surrounding gingival tissue may experience lymphadenopathy. The alveolar plate may exhibit crepitus when palpated.

Periapical cysts exist in two structurally distinct classes:

Periapical true cysts - cysts containing cavities entirely surrounded in epithelial lining. Resolution of this type of cyst requires surgical treatment such as a cystectomy.

Periapical pocket cysts - epithelium lined cavities that have an opening to the root canal of the affected tooth. Resolution may occur after traditional root canal therapy.

Periapical cysts comprise approximately 75% of the types of cysts found in the oral region. The ratio of individuals diagnosed with periapical cysts is 3:2 male to female, as well as individuals between 20 and 60 years old. Periapical cysts occur worldwide.

Types of Periapical cysts:

Apical: 70%

Lateral: 20%

Residual: 10%

This type of classification is based on the amount of impacted tooth that is covered with the mandibular ramus. It is known as the Pell and Gregory classification, classes 1, 2, and 3.

Clinical signs of TRs are often minimal since the discomfort can be minor. However, some authors have described discomfort while chewing, anorexia, dehydration, weight loss, and tooth fracture. The lower third premolar is the most commonly affected tooth.

Classifications enable the oral surgeon to determine the difficulty in removal of the impacted tooth. The primary factor determining the difficulty is accessibility, which is determined by adjacent teeth or other structures that impair access or delivery pathway. The majority of classification schemes are based on analysis on a radiograph. The most frequently considered factors are discussed below.

The main types of dental abscess are:

- Periapical abscess: The result of a chronic, localized infection located at the tip, or apex, of the root of a tooth.

- Periodontal abscess: begins in a periodontal pocket (see: periodontal abscess)

- Gingival abscess: involving only the gum tissue, without affecting either the tooth or the periodontal ligament (see: periodontal abscess)

- Pericoronal abscess: involving the soft tissues surrounding the crown of a tooth (see: Pericoronitis)

- Combined periodontic-endodontic abscess: a situation in which a periapical abscess and a periodontal abscess have combined (see: Combined periodontic-endodontic lesions).

Impacted wisdom teeth without a communication to the mouth, that have no pathology associated with the tooth and have not caused tooth resorption on the blocking tooth rarely have symptoms. In fact, only 12% of impacted wisdom teeth are associated with pathology.

When wisdom teeth communicate with the mouth, the most common symptom is localized pain, swelling and bleeding of the tissue overlying the tooth. This tissue is called the operculum and the disorder called pericoronitis which means inflammation around the crown of the tooth. Low grade chronic periodontitis commonly occurs on either the wisdom tooth or the second molar, causing less obvious symptoms such as bad breath and bleeding from the gums. The teeth can also remain asymptomatic (pain free), even with disease. As the teeth near the mouth during normal development, people sometimes report mild pressure of other symptoms similar to teething.

The term asymptomatic means that the person has no symptoms. The term asymptomatic should not be equated with absence of disease. Most diseases have no symptoms early in the disease process. A pain free or asymptomatic tooth can still be infected for many years before pain symptoms develop.

The pain is continuous and may be described as extreme, growing, sharp, shooting, or throbbing. Putting pressure or warmth on the tooth may induce extreme pain. The area may be sensitive to touch and possibly swollen as well. This swelling may be present at either the base of the tooth, the gum, and/or the cheek, and sometimes can be reduced by applying ice packs.

An acute abscess may be painless but still have a swelling present on the gum. It is important to get anything that presents like this checked by a dental professional as it may become chronic later.

In some cases, a tooth abscess may perforate bone and start draining into the surrounding tissues creating local facial swelling. In some cases, the lymph glands in the neck will become swollen and tender in response to the infection. It may even feel like a migraine as the pain can transfer from the infected area. The pain does not normally transfer across the face, only upwards or downwards as the nerves that serve each side of the face are separate.

Severe aching and discomfort on the side of the face where the tooth is infected is also fairly common, with the tooth itself becoming unbearable to touch due to extreme amounts of pain.

The lateral periodontal cyst is a non-inflammatory developmental cyst that arises from the epithelial post-functional dental lamina, which is a remnant from odontogenesis. It is more common in middle-aged males. Usually asymptomatic, it presents as a regular well-corticated radiolucency on the side of a mandibular canine or premolar root. Histologically, the cyst appears similar to the gingival cyst of the adult, having a non-keratinized squamous epithelial lining. The involved tooth is usually vital and has no indication for root canal treatment unless the signs of non-vital or necrotic pulpal tissue were confirmed. The cysts arise from epithelial rest cells in the periodontal ligament, although it is unknown whether from the cell rests of Malassez, reduced enamel epithelium or dental lamina remnants, and are generally treated by surgical enucleation.

Feline Tooth Resorption (TR) is a syndrome in cats characterized by resorption of the tooth by odontoclasts, cells similar to osteoclasts. TR has also been called "feline odontoclastic resorption lesion" (FORL), neck lesion, cervical neck lesion, cervical line erosion, feline subgingival resorptive lesion, feline caries, or feline cavity. It is one of the most common diseases of domestic cats, affecting up to two-thirds. TRs have been seen more recently in the history of feline medicine due to the advancing ages of cats, but 800-year-old cat skeletons have shown evidence of this disease. Purebred cats, especially Siamese and Persians, may be more susceptible.

TRs clinically appear as erosions of the surface of the tooth at the gingival border. They are often covered with calculus or gingival tissue. It is a progressive disease, usually starting with loss of cementum and dentin and leading to penetration of the pulp cavity. Resorption continues up the dentinal tubules into the tooth crown. The enamel is also resorbed or undermined to the point of tooth fracture. Resorbed cementum and dentin is replaced with bone-like tissue.

All teeth are classified as either developing, erupted (into the mouth), embedded (failure to erupt despite lack of blockage from another tooth) or impacted. An impacted tooth is one that fails to erupt due to blockage from another tooth.

Wisdom teeth develop between the ages of 14 and 25, with 50% of root formation completed by age 16 and 95% of all teeth erupted by the age of 25. However, tooth movement can continue beyond the age of 25.

Impacted wisdom teeth are classified by the direction and depth of impaction, the amount of available space for tooth eruption. and the amount of soft tissue or bone (or both) that covers them. The classification structure helps clinicians estimate the risks for impaction, infections and complications associated with wisdom teeth removal. Wisdom teeth are also classified by the presence (or absence) of symptoms and disease.

One review found that 11% of teeth will have evidence of disease and are symptomatic, 0.6% will be symptomatic but have no disease, 51% will be asymptomatic but have disease present and 37% will be asymptomatic and have no disease.

Impacted wisdom teeth are often described by the direction of their impaction (forward tilting, or mesioangular being the most common), the depth of impaction and the age of the patient as well as other factors such as pre-existing infection or the presence of pathology. Of these predictors, age correlates best with extraction difficulty and complications during wisdom teeth removal rather than the orientation of the impaction.

Another classification system often taught in U.S. dental schools is known as "Pell and Gregory Classification". This system includes a horizontal and vertical component to classify the location of third molars (predominately applicable to mandibular third molars): the third molar's relationship to the occlusal plane being the vertical or "x-component" and to the anterior border of the ramus being the horizontal or "y-component". Vertically, Class A impaction is one in which the occlusal surface of the impacted tooth is level or nearly level with the occlusal plane and the cervical line of the adjacent second molar.

There are four types of abscesses that can involve the periodontal tissues:

1. Gingival abscess—a localized, purulent infection involves only the soft gum tissue near the marginal gingiva or the interdental papilla.

2. Periodontal abscess—a localized, purulent infection involving a greater dimension of the gum tissue, extending apically and adjacent to a periodontal pocket.

3. Pericoronal abscess—a localized, purulent infection within the gum tissue surrounding the crown of a partially or fully erupted tooth. Usually associated with an acute episode of pericoronitis around a partially erupted and impacted mandibular third molar (lower wisdom tooth).

4. combined periodontal/endodontic abscess

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.

Acute pericoronitis (i.e. sudden onset and short lived, but significant, symptoms) is defined as "varying degrees of inflammatory involvement of the pericoronal flap and adjacent structures, as well as by systemic complications." Systemic complications refers to signs and symptoms occurring outside of the mouth, such as fever, malaise or swollen lymph nodes in the neck.

The botryoid odontogenic cyst is a multi-compartmentalized variant of the lateral periodontal cyst. It is similar to the lateral periodontal cyst in all its features except that its polycystic nature is often evident through its multilocular pattern on radiographs.

Gingival and periodontal pockets are dental terms indicating the presence of an abnormal depth of the gingival sulcus near the point at which the gingival tissue contacts the tooth.

Repair with cementum or dentin occurs after partial root resorption, fusing the tooth with the bone. It may occur following dental trauma, especially occlusal trauma, or after periapical periodontitis caused by pulp necrosis. Ankylosis itself is not a reason to remove a permanent tooth, however teeth which must be removed for other reasons are made significantly more difficult to remove if they are ankylosed.

Pericoronitis may also be chronic or recurrent, with repeated episodes of acute pericoronitis occurring periodically. Chronic pericoronitis may cause few if any symptoms, but some signs are usually visible when the mouth is examined.

Ankylosis of deciduous teeth ("submerged teeth") may rarely occur. The most commonly affected tooth is the mandibular (lower) second deciduous molar. Partial root resorption first occurs and then the tooth fuses to the bone. This prevents normal exfoliation of the deciduous tooth and typically causes impaction of the permanent successor tooth. As growth of the alveolar bone continues and the adjacent permanent teeth erupt, the ankylosed deciduous tooth appears to submerge into the bone, although in reality it has not changed position. Treatment is by extraction of the involved tooth, to prevent malocclusion, periodontal disturbance or dental caries.

In the early stages, periodontitis has very few symptoms, and in many individuals the disease has progressed significantly before they seek treatment.

Symptoms may include:

- Redness or bleeding of gums while brushing teeth, using dental floss or biting into hard food (e.g., apples) (though this may occur even in gingivitis, where there is no attachment loss)

- Gum swelling that recurs

- Spitting out blood after brushing teeth

- Halitosis, or bad breath, and a persistent metallic taste in the mouth

- Gingival recession, resulting in apparent lengthening of teeth. (This may also be caused by heavy-handed brushing or with a stiff toothbrush.)

- Deep pockets between the teeth and the gums (pockets are sites where the attachment has been gradually destroyed by collagen-destroying enzymes, known as collagenases)

- Loose teeth, in the later stages (though this may occur for other reasons, as well)

Patients should realize gingival inflammation and bone destruction are largely painless. Hence, people may wrongly assume painless bleeding after teeth cleaning is insignificant, although this may be a symptom of progressing periodontitis in that patient.

The "severity" of disease refers to the amount of periodontal ligament fibers that have been lost, termed "clinical attachment loss". According to the American Academy of Periodontology, the classification of severity is as follows:

- Mild: of attachment loss

- Moderate: of attachment loss

- Severe: ≥ of attachment loss

Gingival cyst of adult is a rare condition. The incidence is less than 0.5%. It is formed from the rests of dental lamina. It is found in the soft tissues on the buccal and labial portions of the jaw. It usually occurs on the facial gingiva as a single small flesh colored swelling, sometimes with a bluish hue due to the cystic fluid. Sometimes, it may occur in cluster, either unilaterally or bilaterally or on the lingual surface of the alveolar process. It is most commonly seen in the canine and premolar regions of the mandible, and are sometimes confused with lateral periodontal cysts. It is not normally problematic, but when it grows larger, it can cause some discomfort. It can be removed by simple surgical excision. They are developed late in life, generally up to the sixth decade of age.

Odontogenic cysts have histologic origins in the cells of the dental structures. Some are inflammatory while others are developmental.

- Radicular cyst is the most common (up to two thirds of all cysts of the jaws). This inflammatory cyst originated from a reaction to dental pulp necrosis.

- Dentigerous cyst, the second most prevalent cyst, is associated with the crown of non-erupted tooth.

- Odontogenic keratocyst, which now is considered as tumor, and therefore called "Keratocystic odontogenic tumor". This lesion may be associated with the Nevoid basal cell carcinoma syndrome.

- Buccal bifurcation cyst which appears in the buccal bifurcation region of the mandibular first molars in the second half of the first decade of life.

- Eruption cyst; a small cyst in the gingiva as a tooth erupts, forming from the degenerating dental follicle

- Primordial cyst; previous thought to be a unique entity. Most primordial cysts have proven to be Keratocystic odontogenic tumors

- Orthokeratinized odontogenic cyst; a variant of the Keratocystic odontogenic tumor

- Gingival cyst of the newborn; an inclusion cyst from remanents of the dental lamina on a newborn gingiva

- Gingival cyst of the adult; a soft tissue variant of the lateral periodontal cyst

- Lateral periodontal cyst; a non-inflammatory cyst (vs a radicular cyst) on the side of a tooth derived from remanents of the dental lamina

- Calcifying odontogenic cyst; a rare lesion with cystic and neoplastic features and significant diversity in presentation, histology and prognosis

- Glandular odontogenic cyst; cyst with respiratory like epithelial lining and the potential for recurrence with characteristics similar to a central variant of low-grade mucoepidermoid carcinoma

Botryoid odontogenic cyst is a variant of the lateral periodontal cyst. It is more often found in middle-aged and older adults, and the teeth more likely affected are mandibular (lower) canines and premolars. On radiographs, the cyst appears "grape-like". Often patients with this condition are symptomatic.

Cysts rarely cause any symptoms, unless they become secondarily infected. The signs depend mostly upon the size and location of the cyst. If the cyst has not expanded beyond the normal anatomical boundaries of the bone, then there will be no palpable lump outside or inside the mouth. The vast majority of cysts expand slowly, and the surrounding bone has time to increase its density around the lesion, which is the body's attempt to isolate the lesion. Cysts that have expanded beyond the normal anatomic boundaries of a bone are still often covered with a thin layer of new bone. At this stage, there may be a sign termed "eggshell cracking", where the thinned cortical plate cracks when pressure is applied. A lump may be felt, which may feel hard if there is still bone covering the cyst, or fluctuant if the cyst has eroded through the bone surrounding it. A cyst may become acutely infected, and discharge into the oral cavity via a sinus. Adjacent teeth may be loosened, tilted or even moved bodily. Rarely, roots of teeth are resorbed, depending upon the type of cyst. The inferior alveolar nerve runs through the mandible and supplies sensation to the lower lip and chin. As most cysts expand slowly, there will be no altered sensation (anesthesia or paraesthesia), since the inferior alveolar canal is harmlessly enveloped or displaced over time. More aggressive cysts, or acute infection of any cyst may cause altered sensation.