Cavities: Symptoms, Causes & Cavity Fillings

What Are Cavity Fillings?

Dental fillings, also referred to as cavity fillings, are most commonly used to fill minor dental cavities (decaying teeth). Before the filling is placed, a portion of the decaying tooth is removed. Then your dentist fills the cavity with a tooth-colored or metal dental restoration.

There are many uses for cavity fillings. For example, the restorations close the spaces in teeth where bacteria and food particles can enter, which prevents the progression of the decay. Fillings also repair broken, chipped, or worn-down teeth.

Types of Dental Caries (Cavities)

Dental caries, also called carious lesions, is the process that results in tooth cavitation. Incipient lesions are considered “microcavities.” These lesions are limited to enamel only, so they can be "stopped" without a dental filling.

The lesions create chalky white spots on the surfaces of teeth. These white spots turn dark brown or black over time, which is the earliest sign of cavity formation (tooth decay).

There are six different classes of dental caries that result in cavitation, including:

class i cavity

Class I

These carious lesions form in the fissures and pits of teeth, which is why they are called “pit-and-fissure lesions.” They typically occupy the biting surfaces of posterior (back) teeth and the grooves on the top and bottom molars.

class ii cavity

Class II

These lesions occupy the interproximal surfaces of posterior teeth (in between). This includes premolars and molars.

class iii cavity

Class III

These lesions occupy the interproximal surfaces of anterior teeth (in between). This includes incisors and canines, but not the biting edges of the teeth.

class v cavity

Class V

These lesions are found on the gum line of both anterior and posterior teeth. Plaque buildup on the gums is common, which may result in white spots on teeth.

class vi cavity

Class VI

These lesions form on the cusp tips of premolars, molars, and the incisal (biting) edge of incisors and canines.

If cavities are left untreated, tooth loss can occur.

Symptoms of Cavities

Small cavities usually do not cause any symptoms, which is why consistent dental evaluations with x-rays are necessary to catch them early. If a small cavity isn’t filled in time, it will get larger and symptoms typically begin to develop. Although, by the time the symptoms are noticeable by the patient, the cavity is past the point of being fixed with just a filling. Common symptoms of big cavities include:

  • Toothache — recurring tooth pain or pain that occurs without any cause.
  • Tooth Sensitivity — Sharp pain in the tooth caused by thermal stimulation, such as eating or drinking something cold, hot, or sweet.
  • Tooth Holes — once the cavity has developed, noticeable holes typically appear on the tooth.
  • Dark Stains — white spots caused by carious lesions develop into brownish or black spots over time.
  • X-rays — sometimes cavities aren’t noticeable on the surface. If tooth pain or sensitivity is present, a dentist will take an x-ray to check for decay. Dentists also check for cavities during routine check-ups and teeth cleanings every six months.
poor diet

What Causes Cavities?

Plaque formation is the leading cause of cavities. Plaque forms due to the long-term buildup of food particles, oral bacteria, acid, and saliva.

The high acidity content in the plaque attacks the tooth enamel, causing holes and dark spots on teeth. If plaque is left untreated it can turn into hardened dental plaque, also called tartar, which is difficult to remove. The earlier a cavity is caught, the easier it is to treat. Common causes of cavities and plaque buildup include:

Dietary Habits

The primary cause of cavities is from foods and drinks high in sugar, including fruit juices and candy. White starches, such as pasta, bread, chips, and crackers can even cause cavities over time due to their high carbohydrate levels (sugars). Mouth bacteria feed off of simple sugars, which eventually converts into acid plaque.


Smoking itself doesn't cause cavities. Tobacco's main role in cavity formation is the fact that it causes dry mouth, which allows for greater plaque buildup. Over time, smoking can also create dark stains on the teeth. Dentists recommend smokers to avoid acidic foods and drinks that can cause worse stains, such as coffee, soda, and tea. The combination of sugary foods (mentioned above), acidic liquids, and dry mouth can lead to enamel breakdown and cavity formation.

Medications and Dry Mouth

Dry mouth occurs when the salivary glands in the mouth cannot make enough saliva, which is typically caused by some medications. Over time, dry mouth often results in cavity formation. Medications that lead to dry mouth include:

  • Antihistamines
  • Antidepressants
  • Sedatives
  • Pain Medications
  • Parkison’s Disease Medications
  • High Blood Pressure Medications
  • Antacids
  • Decongestants

Poor Oral Hygiene Practices

Brushing twice a day, flossing every day, and rinsing with mouthwash regularly are essential for cavity prevention. Visiting the dentist every six months for teeth cleanings and yearly x-rays is also essential. Doing so allows dentists to catch cavities early and prevent further decay with treatment.

cavity filling

Types of Direct Dental Fillings

There are three main types of direct cavity fillings available, which are restorations made inside of the mouth during one office visit. Direct filling types include:


Composite is a tooth-colored, adhesive bonding material made of glasslike filler particles and acrylic resin. Composites are the most common restorative material for cavity fillings, broken teeth, and chipped teeth. This material fills cavities in posterior teeth (premolars and molars).

  • Advantages — The main advantage of composite fillings is that they are tooth-colored and blend seamlessly with natural teeth. They are relatively strong, durable, and the most aesthetically pleasing direct dental filling available.
  • Disadvantages — Even though composite fillings are strong and durable, they are more susceptible to recurrent cavities than amalgam fillings. Composite restorations last up to five years, while amalgam or silver restorations last 10 to 15 years.


Amalgam is an alloy (mixture) of mercury with silver, tin, and copper. The amount of each element in amalgam varies because there are many different types of alloys. Mercury in dental amalgam is not toxic, strong, and more stable than methyl mercury. Amalgam fillings usually restore posterior teeth (premolars and molars).

  • Advantages — Amalgam fillings last 5-10 years longer than composite restorations. This is because they are the strongest and most durable direct fillings on the market today. Lastly, amalgam dental fillings are also the cheapest restoration available.
  • Advantages — Despite the many advantages of amalgam restorations, they are not as aesthetically pleasing as composite fillings. Although, amalgam restorations are not visible if they repair back molars.

Glass Ionomer Fillings

There are two types of glass ionomer fillings:

  • Conventional Glass Ionomer (CGIs) fillings are another tooth-colored restoration made of polymerizable acids and ion-leachable glass particles. The restoration also releases fluoride, which helps prevent future cavities. Although, glass ionomer is not as durable as amalgam or composite.
  • Resin-Modified Glass Ionomer (RMGI’s) fillings are similar to conventional glass ionomers, but with more strength and added acrylic resins. RMGI’s are typically used to restore primary teeth (baby teeth). They are tooth-colored but not as versatile and aesthetic as composite resins.

Types of Indirect Dental Fillings

Indirect dental fillings are made outside of the mouth, typically in a dental laboratory. They are custom made for each patient depending on their needs, tooth structure, and severity of tooth decay.

Indirect restorations fill cavities that are too large for a simple dental filling (direct filling) and take two office visits to complete.

Types of indirect fillings include:

  • Porcelain fillings are tooth-colored restorations that mimic the function and color of natural teeth. The color of porcelain and natural teeth are almost identical. The fillings are also strong and less likely to fracture than composite fillings. They are ideal for patients who want a long-lasting restoration with aesthetics at the forefront.
  • Gold fillings are the strongest indirect fillings available. They protect weakened teeth cusps caused by trauma, decay, or deep cavities. Unlike composite and porcelain fillings, gold restorations are not aesthetically pleasing. However, they are less prone to damage over time.
dentist appointment

Which Dental Specialists Fill Cavities?

General dentists, family dentists, and pediatric dentists are the main providers of dental fillings for children and adults. They also specialize in other dental care procedures and treatments, including teeth cleanings, restorations, and sealants.

teeth whitening

Treatment Cost & Insurance

The cost of a dental filling depends on the type and the dentist’s location. Since fillings are used to treat cavities, decay, or trauma-related dental conditions, part or most of the procedure is covered by a good dental insurance policy. The prices below reflect procedure costs without insurance:

Amalgam (Silver) Filling
$50-$200 (per tooth)
Composite Filling
$90-$300 (per tooth)
Glass Ionomers
$90-$300 (per tooth)
Indirect Gold or Porcelain Filling
$500-$4500 (per tooth)

Looking for affordable dental care? Save money on common dental services — including teeth cleanings, x-rays, and restorative treatments — today. Learn More


Lygre, David G. General, Organic, and Biological Chemistry. John Wiley, 2003.

Hollins, Carole. Basic Guide to Dental Procedures. John Wiley & Sons, Inc., 2015.

Syrbu, John DDS. The Complete Pre-Dental Guide to Modern Dentistry. 2013.

American Dental Association (ADA), Tackling tooth decay. 2013.

Updated on: May 22, 2020
Alyssa Hill
Medically Reviewed: September 11, 2019
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Lara Coseo