Tooth decay or cavities is one of the most common human diseases. While in adults it is periodontal disease, the main cause of tooth loss in children and young people is cavities. t is a process of destruction of the hard tissues of the tooth (enamel and dentin) caused by the action of bacteria that exist in the mouth.
Below, we explain what cavities are, their causes and risk factors, how you can prevent them, the available treatments, and why it’s important to treat them early to avoid consequences for your overall health.
1) What is tooth decay?
Tooth decay is a multifactorial infectious disease caused by bacteria present in the mouth. These bacteria (mainlyStreptococcus mutans, among others) are part of dental plaque and feed on the sugars we eat.In their metabolism they produce acids capable of gradually demineralizing and destroying tooth enamel. The initial result is the appearance of a small lesion on the tooth (white spot or incipient cavity) which, if left untreated, can progress to a cavity increasingly deeper into the tooth structure. Once the decay penetrates the enamel and reaches the dentin (the softer inner layer), its progress accelerates. If the process is not stopped in time, the infection can invade the dental pulp (the nerve), causing the typical intense toothache. In advanced stages, caries can cause nerve necrosis and form an abscess in the root, putting the tooth at risk and even requiring extraction.
1A) Who is affected by tooth decay?
It is important to note that cavities can affect people of all ages in very young children, the so-calledearly childhood cariesthebaby bottle tooth decay, an aggressive cavity that affects baby teethIn older adults, receding gums can expose the roots of the teeth, which lack enamel and are more susceptible to decay (root caries). Untreated tooth decay is extremely prevalent worldwide: according to theWorld Health Organization, constitutes the most common health disorder in the population, affecting billions of people. In fact, it is estimated that practically 100% of adults develop cavities at some point in their lives, and between 60% and 90% of children are also affected. Despite its frequency, it is important to remember that it is a disease largely preventable with good habits.
2) Symptoms of tooth decay
In their initial stages, caries is usually silent and does not cause any noticeable symptoms. As the enamel loses minerals, a slight, opaque whitish stain may be noticeable on the surface of the tooth (an early lesion). However, when caries progresses and forms a deeper cavity, various symptoms and warning signs begin to appear:
- Dental sensitivity– Mild discomfort or pain when consuming food or drinks sweet, cold or hot, due to the exposure of the underlying dentin. It is common to feel a small cramp or twinge on the affected tooth by drinking, for example, very cold water or sweets.
- Toothache– Dental pain more intense and persistent which may appear spontaneously or when chewing. It indicates that the decay has reached near the pulp or has invaded it. Toothache can range from moderate to very severe and even disabling, often worse at night.
- Visible cavity or dark spot– In already developed caries, a hole on the tooth or a brownish-black stain on its surface. These lesions often retain food and are rough to the touch of the tongue.
- Infection and abscess– If the caries reaches the nerve and bacteria infect the pulp, a cavity can form dental abscess (phlegmon). An abscess is a collection of pus in the bone or gum next to the tooth, and causes severe pain, facial swelling, and even fever in some cases, the gum around the tooth may be red and very sensitive to the touch.
Not all of these symptoms appear simultaneously; for example, it’s possible to have cavities in several teeth without pain (only detectable by the dentist), or to experience pain at an advanced stage without having noticed any prior sensitivity. When caries is suspected – for example, if you notice a tooth decay, localized pain, or increased sensitivity – you should go to the dentist as soon as possible. Early diagnosis through clinical examination and X-rays makes caries easier to treat, before it causes further damage.

3) Causes and factors that influence the development of dental caries
Caries is a process multifactorial and knowing these causes can help you work on preventing them. For it to appear, several factors must coincide: a susceptible dental surface, the bacteria adequate, the sugary substrates that they feed them and the time enough to cause damage. Below we analyze the main risk factors or elements that influence the development of cavities:
3A) The quality of the enamel
The tooth enamel is the hardest layer of the tooth (in fact, it is the hardest tissue in the entire human body). However, its resistance varies from person to person. Genetics, nutrition during tooth formation and other factors determine the enamel quality and its ability to resist acid attack from bacteria. Weaker or thinner enamel will be more prone to developing cavities.
3Aa) Baby teeth are more prone to developing cavities
For example, baby teeth have thinner, more porous enamel, which explains why they are more vulnerable to rapid cavities in childhood.
3Ab) Fluoride increases the strength of tooth enamel
Likewise, the presence of fluoride in the enamel structure increases its strength; therefore, a lack of fluoride during tooth development can result in less resistant enamel and a greater predisposition to cavities.
In summary, strong and well-mineralized teeth will tolerate acids better, while teeth with defective or poorly mineralized enamel are more easily damaged.
3B) At the dental plaque
The dental plaque or bacterial plaque is that film sticky white-yellowish that continually forms on our teeth. It is composed of millions of bacteria mixed with food debris and saliva components. If we don’t remove plaque in time through oral hygiene, bacteria proliferate in it and produce acids that begin to demineralize the enamel- Plaque tends to accumulate especially in the fissures of the molars, between the teeth and near the gum.poor hygienefavors its accumulation; on the contrary,Brushing properly after meals and flossing removes plaque before it causes damage.Plaque that remains stuck to teeth for a long time eventually hardens and turns into tartar (dental calculus), which can no longer be removed by brushing and continues to harbor bacteria. Therefore, the prolonged presence of plaque It’s a key factor in the formation of cavities. A clean mouth is unlikely to develop active cavities, while in a mouth with abundant plaque, bacteria will wreak havoc on the enamel.
3C) Cariogenic foods
3Ca) Fermentable carbohydrates
The diet plays a fundamental role in the development of cavities. Plaque bacteria primarily metabolize fermentable carbohydrates (sugars and starches) to obtain energy. In doing so, they generate acids that demineralize the tooth. Therefore, a diet rich in sugars promotes the development of cavities, while a low-sugar diet significantly reduces the risk. It’s not just the amount of sugar that matters, but also the frequency with which it is consumed and the consistency of your food. Additionally, choosing healthier foods—vegetables, proteins, low-acid fresh fruits, and sugar-free dairy products—helps protect your teeth.

3Cb) Sticky foods
Eating sticky sweets between meals is especially harmful: for example, candies, jelly beans, pastries, chocolate, cookies, sugary soft drinks, etc., are highly cariogenic foods. These types of foods provide a constant substrate for bacteria.
3Cc) The frequency with which sugar is ingested
Every time we eat sugar, in the next 20 minutes bacteria produce acid that attacks the enamel. If we pick frequently, we chain acid attacks one after another, the tooth doesn’t have time to recover. However, by limiting sugar consumption to main meals (and brushing afterward), we give saliva and fluoride a chance to remineralize the enamel.
3D) Salivary flow
The saliva is the great natural ally of our oral health. It performs several protective functions: it neutralizes the acids produced after food intake, provides minerals (calcium, phosphate) that help remineralize the enamel and contains antibacterial components. When saliva production decreases, teeth are less protected against cavities. Situations such as xerostomia (pathological dry mouth), dehydration, habitual mouth breathing, or certain medications that reduce salivary flow significantly increase the risk of cavities. At night, for example, we secrete less saliva, which explains why bacteria have a free hand to act during sleep. Hence the importance of brushing before bed: it’s the time of day when we most need to keep our mouths clean, as we’ll have many hours with little saliva and without eating anything (which lowers the mouth’s pH). Under normal conditions, saliva buffers acids after eating in about 20-30 minutes and facilitates the repair of damaged enamel. But if saliva is lacking, the pH can remain low for longer and demineralization progresses. In conclusion, an adequate salivary flow protects against cavities, while dry mouth aggravates them. Drinking water frequently, stimulating salivation (for example, by chewing sugar-free gum), and medically treating xerostomia when present are important measures to keep cavities at bay.
In short, the appearance of caries requires the conjunction of the above factors. To this we can add a fourth factor, time unhygienic. The good news is that all these factors are modifiable except for genetics. We can act with prevention measures such as diet, plaque control, strengthening enamel with fluoride, and taking care of salivation, greatly reducing the likelihood of developing cavities.

4) How to prevent tooth decay
Although caries is widespread, Its prevention is relatively simple If we consistently adopt healthy habits. The keys to prevention can be summarized in five points: rigorous oral hygiene, fluoride use, proper nutrition, professional measures (such as sealants), and regular checkups. We explain each aspect below:
4A) Maintain proper dental hygiene
Maintain a good oral hygiene It is the most effective preventive measure against cavities. The objective is prevent the accumulation of bacterial plaque on the teeth, since, as we saw, plaque is the direct cause of enamel demineralization. To achieve this, it is recommended brush your teeth after each main meal (at least twice a day, in the morning and especially before going to bed) using a toothpaste with fluoride.Brushing should be done with thecorrect technique, during 2-3 minutes, making sure to clean all surfaces of each tooth. It is important to use a brush in good condition (change it every 3 months approx.) and don’t forget the language and the gum line. In addition to brushing, it is essential clean between teeth daily with dental floss or interdental brushes, since cavities often start in spaces where a toothbrush can’t reach. If you are prone to cavities or have many restorations, your dentist may also recommend using a mouthwash with fluoride at night. Maintaining these hygiene habits greatly reduces the presence of plaque and therefore reduces the incidence of caries In people with a high predisposition, the use of other aids such as oral irrigators or more frequent professional dental cleanings may even be considered. In summary, Clean teeth are unlikely to decay Consistent brushing and flossing, along with fluoride toothpaste, is the first line of defense against cavities.
4B) Don’t forget to floss!
The use of dental floss Prevents the appearance of interproximal caries and helps keep our gums healthy. This helps remove food debris and bacteria that may accumulate between your teeth. It’s also important to keep your tongue clean, as it’s where the largest number of bacteria in the mouth accumulate. You can do this with a toothbrush or special devices such as tongue scrapers.
4C) The importance of fluoride
The most notable function of fluoride is its ability to help prevent demineralization of tooth enamel. Numerous studies have shown that fluoride strengthens tooth enamel.and makes it more resistant to acid attack produced by bacterial plaque. Fluoride is incorporated into the enamel structure (during tooth formation and also topically afterward) forming fluorapatite crystals, which are harder and less soluble than the original hydroxyapatite. Thus, teeth treated with fluoride show less demineralization under the same acid attack. Furthermore, fluoride promotes remineralization of the initial damaged areas: it attracts calcium and phosphate towards the incipient lesions of the enamel, helping to repair them before cavities form. It even has a antibacterial effect at high concentrations, inhibiting bacterial enzymes and reducing acid production. Therefore, regular use of fluoride can stop and even reverse early caries before it moves forward.
4Ca) Main sources of fluoride
In practice, the main sources of fluoride are: fluoride toothpastes (minimum 1000 ppm fluoride ion for children and 1450 ppm for adults), the fluoride mouthwashes (for weekly or daily use as directed), the drinking water (in some cities the running water is fluoridated naturally or artificially) and the gels or varnishes fluoride applied by the dentist periodically. Although in some cases it is advisable to increase fluoride intake, the amount contained in tap water is usually sufficient.It’s important to follow professional recommendations regarding the amount of fluoride, especially for children, to maximize its benefits and avoid excesses. In short, Fluoride strengthens teeth and prevents cavities– is a safe and effective ally when used properly.
4D) Maintain a proper diet
The type of diet is key in the development of cavities, since sugars and carbohydrates are precisely the food for bacteria. Following a cariogenic diet, that is, one where there is a frequent consumption of sweets and carbohydrates will promote the appearance of cavities and vice versa, eating a varied diet rich in fruits, vegetables, fiber, meats, and fish will prevent cavities. However, the most important way to prevent cavities is to brush your teeth after every meal.
4E) Dental sealing of pits and fissures
The pit and fissure sealantsThey are an excellent preventive method,especially in children and adolescentsThey consist of a thin layer of resin that the dentist applies tocoat and seal the rough surfaces of grinding wheels, where bacteria and food debris often lodge. By sealing deep fissures, a physical barrier is created that prevents plaque from penetrating and forming cavities in these vulnerable grooves. The placement of sealants isfast, painless and non-invasiveFirst, the tooth surface is cleaned and prepared with a special solution, then the liquid resin is applied to the fissures and hardened with light (photopolymerization). The result is a hard, virtually invisible coating that can last for years.
4Ea) Dental sealing of pits and fissures
Several studies have shown that children with sealants on their permanent molars presentmuch fewer cavitiesthan unsealed teeth. Therefore, it is recommended to seal newly erupted permanent molars (usually around 6-7 years of age for the first molars and 11-13 years for the second molars), and high-risk baby teeth can also be sealed. Dental sealantssignificantly reduce the appearance of cavitieson the occlusal surfaces of molars, making them a very useful preventive tool. Consult with your pediatric dentist about this measure; it’s often part of pediatric preventive dentistry programs. At Clínica Pardiñas, we routinely apply sealants to young patients with great effectiveness.
4F) Visiting the dentist regularly prevents the appearance of cavities
Go to the dentist periodically It is another key element in preventing and controlling cavities. A dental checkup is recommended at least once a year (preferably two) even when there is no discomfort. During these visits, the dentist will thoroughly examine your teeth, gums, and plaque residue, and may detect early cavities before they produce symptoms. Identifying a cavity early allows it to be treated with a small filling, preventing it from spreading to deeper layers. In addition, during the consultation, the professional will perform a professional dental cleaning If necessary, removing tartar and plaque buildup in difficult areas that brushing can’t reach. This prophylaxis helps keep teeth free of bacterial deposits, making it difficult for new cavities to form. Your dentist may also apply preventive treatments During checkups, such as concentrated fluoride varnishes on teeth at higher risk, or filling in small cracks before they damage the tooth. On the other hand, checkups are opportunities to receive personalized hygiene and dietary instructions, and to evaluate other factors (tooth position, quality of previous fillings, mouthwash use, etc.). In children and adolescents, regular visits allow for monitoring tooth eruption and applying sealants at the appropriate time.

5) Treatments for tooth decay
Following preventive measures can help control the onset of cavities, but if they have developed, intervention is necessary. Treatment for cavities will depend on their level of development and, therefore, whether or not the dental nerve can be restored fillings, inlays and root canals are the most common treatments for tooth decay.
5A) The filling or obturation
He dental filling (also calledobturationthecomposite restoration) is the most common and conservative solution for treating cavities that have not reached the nerve. The procedure consists of remove all decayed tissue of the tooth using rotary instruments (bur) or manual methods, and then fill the resulting cavity with a biocompatible material that restores the tooth’s shape and function.
5Aa) Materials used in dental fillings
Nowadays, the material of choice is usually the composite resin (composite), a tooth-colored polymer that chemically bonds to enamel and dentin. There are also silver amalgam fillings (a mercury alloy that is increasingly becoming obsolete for aesthetic, health, and environmental reasons) and other materials such as glass ionomer in certain cases. A composite filling is placed in layers, each layer hardening with halogen light, until the tooth’s anatomy is reconstructed. Finally, it is polished smooth and fits the bite. Fillings are quick (in a single session) and preserve most of the healthy tooth. However, when decay is very extensive and has destroyed a large part of the dental crown,a direct filling may be may not be enough.
5Ab) Caution, fillings may fail!
Although it is a common treatment and is usually carried out successfully, it can also fail. A poorly performed dental filling can be a major source of debris accumulation. Food and plaque can accumulate, which can cause cavities to form beneath the filling or leaks. In this case, the filling must be redone, removing the remaining caries and maintaining proper contact with the adjacent tooth.
5B) Dental inlays/onlays
When the destruction of the tooth is too large for a conventional filling, but there is still enough healthy structure and we want to avoid a full crown, the alternative is a dental inlay. Inlays (also known by their English namesinlay and onlay, depending on its length). They are restorations indirect: They are custom-made in the laboratory or using CAD/CAM technology, and then cementan into the tooth cavity, fitting like a puzzle piece. In other words, instead of gradually placing the material into the tooth (as with a filling), the dentist first takes a mold or digital scan of the cavity once the cavity is removed and creates a solid piece to replace the missing portion.
5Ba) Inlays
The inlays are used for cavities within the cusps of the tooth (like wide fillings but they do not cover the tips).
5Bb) Onlays
The onlays cover at least one damaged dental cusp.
5Bc) Overlays
There is also the overlay that covers the entire masticatory surface without becoming a complete crown.
The inlays can be of porcelain (ceramic), of resin the one of air (the latter are no longer used for aesthetic reasons). They offer great durability, a precise fit, and preserve more healthy teeth than a crown. They are recommended for molars or premolars with extensive cavities but with the nerve still alive. The procedure typically involves two sessions: in the first, the decay is removed and an impression is taken, placing a temporary filling; and in the second, the final inlay is fitted and cemented. This type of restoration preserves dental structure better than a crown and restores functionality with high accuracy. At Clínica Pardiñas, we perform porcelain inlays with excellent aesthetic and functional results.
5C) Endodontics
When an advanced cavity has affected the pulp and the damage is irreversible, the treatment to be performed would beendodonticsIn this procedure, the nerve of the tooth is “killed”and it consists precisely inremove the infected pulp, disinfect the inside of the root canals and seal them hermetically with a filling material.First, all infected material is removed from the tooth. Then, a series of files of varying lengths and widths are used to remove all infected material from the roots. The area is irrigated with disinfectant fluid and dried. Finally, the roots and interior of the tooth are sealed with various materials. In some cases, the destruction of the tooth is so extensive that once the root canal treatment is completed, the tooth may be very weak, requiring an inlay or crown.
5D) The dental crown
When the destruction of the tooth by caries is very extensive – for example, if less than 50% of the original healthy crown remains – restorative treatment is likely to include a dental crown. A crown (or cap) is a tooth-shaped covering that is placed over the entire remaining natural tooth.To do this, the dentist first wear and size the affected tooth giving it a conical shape and reducing its size, then taking a mold and making a custom crown (of porcelain, zirconium, metal-porcelain or other material) which then cement over the carved tooth, covering it completely. Crowns restore the tooth’s shape, function, and aesthetics and, very importantly, protect the weakened tooth from fractures or new cavities, since they isolate it from the oral environment.
5Da) The dental crown in very advanced caries
In cases of very advanced caries, after performing root canal treatment, it is common to reconstruct the dental stump with a post and then place a crown. In fact, the crown is usually thelast phaserehabilitation of a severely destroyed tooth: first the caries is removed (and a root canal is performed if there is pulp infection), then the base is rebuilt and finally covered with a crown. A well-fitting crown can prolong the life of a damaged tooth for many years. Depending on the case, your dentist will recommend one type of crown or another (all-ceramic, metal-ceramic, zirconium, etc.), prioritizing strength in the posterior teeth and aesthetics in the anterior teeth.
5Db) Types of dental crowns
Keep in mind that this is the most extensive treatment within dental conservation; if a tooth is so destroyed that even a crown is not viable, then the only alternative is extraction and subsequent replacement (implant or bridge). That’s why the idea is avoid reaching these extremes through the prevention and early treatment of caries.

6) The consequences of caries and its influence on general health
Once caries penetrates the enamel, its progress is unstoppable since dentin, the structure beneath the enamel, is much more fragile, symptoms may appear, ranging from sensitivity, mild pain, or discomfort to severe, debilitating pain, accompanied by abscesses and even fever.We tend to think of cavities as a problem located “only in the mouth,” but the reality is that a poor oral health affects the entire body. A tooth decay that is not treated in time can trigger infections and other complications that go beyond the affected tooth. In fact, OMS warns that oral diseases (mainly caries and periodontal disease), despite being preventable, represent a heavy health burden in many countries and can cause pain, discomfort, infection, and even death in extreme cases.
6A) Chronic pain and nutritional impairment
A tooth with advanced caries causes pain when chewing and prevents us from eating normally. This can lead to nutritional problems, weight loss, or digestive disorders due to insufficient chewing. In children, chronic toothache affects their concentration at school and their quality of life; in adults, it can impair work performance and overall well-being.
6B) Severe infections and abscesses
When the decay reaches the nerve and forms an abscess, the infection can spread from the tooth to the surrounding tissues and even to other parts of the body. An untreated dental abscess can progress to facial cellulitis (diffuse infection of the face or neck) and, in rare cases, even lead to serious complications such as a generalized infection. There are documented cases of patients, including children, who have suffered hospitalizations and even deaths due to an infection caused by a cavity that wasn’t treated in time. Therefore, a dental infection should never be underestimated: it’s important to seek emergency medical attention if there’s facial swelling, difficulty swallowing, or fever associated with a diseased tooth.
6C) Bacterial endocarditis
Oral bacteria can enter the bloodstream through bleeding gums or injuries, especially if there is inflammation and poor hygiene. In people with certain preexisting heart conditions, these circulating microorganisms can lodge in the heart valves and cause ainfective endocarditis, a serious disease. Traditionally, endocarditis has been associated more with periodontal disease, but aheavily infected cavity with abscesscould act as a septic focus as well.
6D) Relationship with diabetes
Numerous studies have shown a bidirectional relationship between diabetes and periodontal health, which also affects cavities. Patients withdiabetes mellitusPoorly controlled periodontal disease is more prone to infections, including rampant cavities and gum disease. In turn, the presence of chronic oral infections can make blood sugar control difficult for diabetics. The inflammation and bacteria associated with periodontal disease and advanced cavities act as an additional stress on the body, worsening insulin resistance. Therefore, maintaining a healthy mouth is especially important for people with diabetes, as healthy gums and teeth help keep metabolic disease under better control, and vice versa
6E) Complications in pregnancy
Pregnant women with poor oral health, including severe cavities and gum disease, may have an increased risk of premature birth or low birth weight baby. According to some research, the hypothesis is that chronic infections and inflammation in the mother (e.g., periodontitis aggravated by caries and poor hygiene) release systemic inflammatory mediators that can trigger preterm delivery. While more evidence is needed in this field, gynecologists and dentists recommend that pregnant women take extreme care of their oral health. Treatments such as fillings or even root canals are safe during pregnancy and preferable to leaving active foci of infection.
6F) Pulpitis, a common cause of toothache
Pulpitis is an inflammation of the dental pulp or nerve, which is the vascular and nervous component inside the tooth. This inflammation causes pain when exposed to stimuli such as cold, heat, pressure, and chewing, although in some cases it can trigger continuous pain. Reversible pulpitis is defined as when the nerve can recover after treatment, and irreversible pulpitis is defined as when it can no longer recover.
7) Caries treatment in A Coruña
As you can see, tooth decay is a very common disease, but it’s easily preventable and repairable. If you live in A Coruña or another Galician city, at Clínica Pardiñas we are specialists in the subject and will be happy to help you. If not, we hope these tips can help. Wherever you’re from, don’t forget to bring proper hygiene and diet and visiting your dentist regularly. Your oral health will thank you.




