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 symptoms of gingivitis are somewhat non-specific and manifest in the gum tissue as the classic signs of inflammation:

- Swollen gums

- Bright red or purple gums

- Gums that are tender or painful to the touch

- Bleeding gums or bleeding after brushing and/or flossing

- Bad breath (halitosis)

Additionally, the stippling that normally exists in the gum tissue of some individuals will often disappear and the gums may appear shiny when the gum tissue becomes swollen and stretched over the inflamed underlying connective tissue. The accumulation may also emit an unpleasant odor. When the gingiva are swollen, the epithelial lining of the gingival crevice becomes ulcerated and the gums will bleed more easily with even gentle brushing, and especially when flossing.

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.

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.

Gingivitis is a non-destructive disease that occurs around the teeth. The most common form of gingivitis, and the most common form of periodontal disease overall, is in response to bacterial biofilms (also called plaque) that is attached to tooth surfaces, termed "plaque-induced gingivitis".

While some cases of gingivitis never progress to periodontitis, data indicates that periodontitis is always preceded by gingivitis.

Gingivitis is reversible with good oral hygiene; however, without treatment, gingivitis can progress to periodontitis, in which the inflammation of the gums results in tissue destruction and bone resorption around the teeth. Periodontitis can ultimately lead to tooth loss. The term means "inflammation of the gum tissue".

Increased sensitivity to stimuli, specifically hot and cold, is a common symptom of pulpitis. A prolonged throbbing pain may be associated with the disease. However, pulpitis can also occur without any pain.

A person experiencing caries may not be aware of the disease. The earliest sign of a new carious lesion is the appearance of a chalky white spot on the surface of the tooth, indicating an area of demineralization of enamel. This is referred to as a white spot lesion, an incipient carious lesion or a "microcavity". As the lesion continues to demineralize, it can turn brown but will eventually turn into a cavitation ("cavity"). Before the cavity forms, the process is reversible, but once a cavity forms, the lost tooth structure cannot be regenerated.

A lesion that appears dark brown and shiny suggests dental caries were once present but the demineralization process has stopped, leaving a stain. Active decay is lighter in color and dull in appearance.

As the enamel and dentin are destroyed, the cavity becomes more noticeable. The affected areas of the tooth change color and become soft to the touch. Once the decay passes through enamel, the dentinal tubules, which have passages to the nerve of the tooth, become exposed, resulting in pain that can be transient, temporarily worsening with exposure to heat, cold, or sweet foods and drinks. A tooth weakened by extensive internal decay can sometimes suddenly fracture under normal chewing forces. When the decay has progressed enough to allow the bacteria to overwhelm the pulp tissue in the center of the tooth, a toothache can result and the pain will become more constant. Death of the pulp tissue and infection are common consequences. The tooth will no longer be sensitive to hot or cold, but can be very tender to pressure.

Dental caries can also cause bad breath and foul tastes. In highly progressed cases, an infection can spread from the tooth to the surrounding soft tissues. Complications such as cavernous sinus thrombosis and Ludwig angina can be life-threatening.

Early childhood caries (ECC), also known as "baby bottle caries," "baby bottle tooth decay" or "bottle rot," is a pattern of decay found in young children with their deciduous (baby) teeth. The teeth most likely affected are the maxillary anterior teeth, but all teeth can be affected. The name for this type of caries comes from the fact that the decay usually is a result of allowing children to fall asleep with sweetened liquids in their bottles or feeding children sweetened liquids multiple times during the day.

Another pattern of decay is "rampant caries", which signifies advanced or severe decay on multiple surfaces of many teeth. Rampant caries may be seen in individuals with xerostomia, poor oral hygiene, stimulant use (due to drug-induced dry mouth), and/or large sugar intake. If rampant caries is a result of previous radiation to the head and neck, it may be described as radiation-induced caries. Problems can also be caused by the self-destruction of roots and whole tooth resorption when new teeth erupt or later from unknown causes.

Children at 6–12 months are at increased risk of developing dental caries. For other kids aged 12–18 months, dental caries develop on primary teeth and approximately twice yearly for permanent teeth.

There are two types of TR. "Type 1" lesions are focal defects often caused by local inflammation. "Type 2" lesions are characterized by a generalized loss of root radiopacity on a dental radiograph. The definitive cause of type 2 TRs is unknown, but histologically destruction of the cementum and other mineralized tissue of the tooth root by odontoclasts is seen. It occurs secondary to the loss of the protective covering of the root (the periodontal ligaments) and possibly to a stimulus such as periodontal disease and the release of cytokines, leading to odontoclast migration. However, FORLs can develop in the absence of inflammation. The natural inhibition to root resorption provided by the lining of the root may be altered by increased amounts of Vitamin D, in cats supplied by their diet.

Abrasion is a pathological, non-carious tooth loss that most commonly affects the premolars and canines. Abrasion frequently presents at the cemento-enamel junction and can be caused by many contributing factors, all with the ability to affect the tooth surface in varying degrees.

Sources of abrasion may arise from oral hygiene habits such as toothbrushes, toothpicks, floss, and dental appliance or may arise from other habits such as nail biting, chewing tobacco or another object. Abrasion can also occur from the type of dentifrice being utilized as some have more abrasive qualities such as whitening toothpastes.

The appearance may vary depending on the aetiology of abrasion, however most commonly presents in a V-shaped caused by excessive lateral pressure whilst tooth-brushing. The surface is shiny rather than carious, and sometimes the ridge is deep enough to see the pulp chamber within the tooth itself.

In order for successful treatment of abrasion to occur, the aetiology first needs to be identified and ceased, e.g. overzealous brushing. Once this has occurred subsequent treatment may involve the changes in oral hygiene or toothpaste, application of fluoride to reduce sensitivity or the placement of a restoration to aid in reducing the progression of further tooth loss.

Acute periapical periodontitis, also termed acute apical periodontitis, acute periradicular periodontitis, or symptomatic periapical periodontitis.

Pulpitis is inflammation of dental pulp tissue. The pulp contains the blood vessels the nerves and connective tissue inside a tooth and provides the tooth’s blood and nutrients. Pulpitis is mainly caused by bacteria infection which itself is a secondary development of caries (tooth decay). It manifests itself in the form of a toothache.

Opacities due to MIH can be quite visible especially on anterior teeth which could present as a problem aesthetically. Patients frequently claim aesthetic discomfort when anterior teeth are involved. The discoloured appearance of the anterior teeth could also have negative effects on a child’s psychological development and self-esteem.

The lesions that appear in teeth affected with MIH can present as opacities that vary from white to yellow-brown. They are usually asymmetrical in appearance, with a sharp demarcation that distinguishes between normal and affected enamel. The lesions usually do not involve the cervical third of affected teeth.

The radiographic features of periapical inflammatory lesions vary depending on the time course of the lesion. Because very early lesions

may not show any radiographic changes, diagnosis of these lesions relies solely on the clinical symptoms . More chronic lesions may show lytic (radiolucent) or sclerotic (radiopaque) changes, or both.

Dentin hypersensitivity (abbreviated to DH, or DHS, and also termed sensitive dentin, dentin sensitivity, cervical sensitivity, and cervical hypersensitivity) is dental pain which is sharp in character and of short duration, arising from exposed dentin surfaces in response to stimuli, typically thermal, evaporative, tactile, osmotic, chemical or electrical; and which cannot be ascribed to any other dental disease.

A degree of dentin sensitivity is normal, but pain is not usually experienced in everyday activities like drinking a cooled drink. Therefore, although the terms "dentin sensitivity" and "sensitive dentin" are used interchangeably to refer to dental hypersensitivity, the latter term is the most accurate.

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.

Acid erosion often coexists with abrasion and attrition. Abrasion is most often caused by brushing teeth too hard.

Any frothing or swishing acidic drinks around the mouth increases the risk of acid erosion.

The pain is sharp and sudden, in response to an external stimulus. The most common trigger is cold, with 75% of people with hypersensitivity reporting pain upon application of a cold stimulus. Other types of stimuli may also trigger pain in dentin hypersensitivity, including:

- Thermal – hot and cold drinks and foods, cold air, coolant water jet from a dental instrument.

- Electrical – electric pulp testers.

- Mechanical–tactile – dental probe during dental examination, periodontal scaling and root planing, toothbrushing.

- Osmotic – hypertonic solutions such as sugars.

- Evaporation – air blast from a dental instrument.

- Chemical – acids, e.g. dietary, gastric, acid etch during dental treatments.

The frequency and severity with which the pain occurs are variable.

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.

The reported symptoms are very variable, and frequently have been present for many months before the condition is diagnosed. Reported symptoms may include some of the following:

- Sharp pain when biting on a certain tooth, which may get worse if the applied biting force is increased. Sometimes the pain on biting occurs when the food being chewed is soft with harder elements, e.g. seeded bread.

- "Rebound pain" i.e. sharp, fleeting pain occurring when the biting force is released from the tooth, which may occur when eating fibrous foods.

- Pain when grinding the teeth backward and forward and side to side.

- Sharp pain when drinking cold beverages or eating cold foods, lack of pain with heat stimuli.

- Pain when eating or drinking sugary substances.

- Sometimes the pain is well localized, and the individual is able to determine the exact tooth from which the symptoms are originating, but not always.

If the crack propagates into the pulp, irreversible pulpitis, pulpal necrosis and periapical periodontitis may develop, with the respective associated symptoms.

Dental fluorosis (also termed mottled enamel) is an extremely common disorder, characterized by hypomineralization of tooth enamel caused by ingestion of excessive fluoride during enamel formation.

It appears as a range of visual changes in enamel causing degrees of intrinsic tooth discoloration, and, in some cases, physical damage to the teeth. The severity of the condition is dependent on the dose, duration, and age of the individual during the exposure. The "very mild" (and most common) form of fluorosis, is characterized by small, opaque, "paper" white areas scattered irregularly over the tooth, covering less than 25% of the tooth surface. In the "mild" form of the disease, these mottled patches can involve up to half of the surface area of the teeth. When fluorosis is moderate, all of the surfaces of the teeth are mottled and teeth may be ground down and brown stains frequently "disfigure" the teeth. Severe fluorosis is characterized by brown discoloration and discrete or confluent pitting; brown stains are widespread and teeth often present a corroded-looking appearance.

People with fluorosis are relatively resistant to dental caries (tooth decay caused by bacteria), although they may be of cosmetic concern. In moderate to severe fluorosis, teeth are physically damaged.

In dentistry, calculus or tartar is a form of hardened dental plaque. It is caused by precipitation of minerals from saliva and gingival crevicular fluid (GCF) in plaque on the teeth. This process of precipitation kills the bacterial cells within dental plaque, but the rough and hardened surface that is formed provides an ideal surface for further plaque formation. This leads to calculus buildup, which compromises the health of the gingiva (gums). Calculus can form both along the gumline, where it is referred to as supragingival ("above the gum"), and within the narrow sulcus that exists between the teeth and the gingiva, where it is referred to as subgingival ("below the gum").

Calculus formation is associated with a number of clinical manifestations, including bad breath, receding gums and chronically inflamed gingiva. Brushing and flossing can remove plaque from which calculus forms; however, once formed, it is too hard and firmly attached to be removed with a toothbrush. Calculus buildup can be removed with ultrasonic tools or dental hand instruments (such as a periodontal scaler).

The two main classification systems are described below. Others include the tooth surface fluorosis index (Horowitz et al. 1984), which combines Deans index and the TF index; and the fluorosis risk index (Pendrys 1990), which is intended to define the time at which fluoride exposure occurs, and relates fluorosis risk with tooth development stage.

Internal resorption may sometimes follow dental trauma (although in other cases it appears unrelated). This is where the dentin is resorbed and replaced instead by hyperplastic, vascular pulp tissue. As this process starts to approach the external surface of the tooth, a pink hue of this replacement pulp tissue may become visible through the remaining overlying tooth substance. This appearance is sometimes termed "pink tooth of Mummery".