What Causes Tooth Decay?

Various conditions, systemic, genetic, environmental or behavioral may increase significantly the risk of developing tooth decay. These risk factors for dental caries include the following:

Dry mouth

People with reduced salivary flow (dry mouth) or increased saliva viscosity are at a higher risk of developing tooth decay. Saliva plays a significant role in protecting teeth from cavities by neutralizing the acids that cause tooth demineralization (decay) and providing minerals to help the remineralization process. Saliva has also some antibacterial properties which can inhibit the growth of dental plaque bacteria. Dry mouth is considered one of the most common causes of tooth decay among the elderly population. Other causes of tooth decay related to reduced amount of saliva include:

• Use of medicines such as some antidepressants, antiepileptic medicines, beta-blockers etc.
• Radiotherapy can also often lower the levels of saliva production.

Low fluoride levels

Fluoride protects the teeth from dental caries in a number of ways; slowing down the enamel loss from demineralisation, enhancing the remineralization process, and inhibiting oral bacteria's ability to create acids. Lack of or lower levels of fluoride weaken the body’s shield against cavities. Possible reasons that you may not get sufficient amounts of fluoride include:

• Low fluoride concentration in local water supply
• Poor diet in foods containing fluoride (tea, milk, fish etc.)
• Not using fluoride toothpastes or mouthwash

Dental defects

People with dental defects affecting tooth structures are more prone to dental caries:

• Amelogenesis Imperfecta - A rare genetic disorder characterized by defective (poorly calcified) tooth enamel.
• Pits and fissures – teeth with deep pits, fissures or grooves that are not wide enough to be cleaned by the toothbrush’s bristles can easily trap bacteria and acids that will cause tooth decay.
• Cracked teeth – a crack on a tooth provides an entrance for bacteria and acids into the enamel
• Crowded teeth – if the teeth are crowded or misaligned they are difficult to clean. Food and bacteria can be trapped between them creating a tooth cavity.

Existing Dental Restorations

Patients who already have dental restorations because they had dental caries in the past are in higher risk of tooth decay in the future, because of several reasons:

• Sometimes the edges of dental fillings or crowns do not perfectly fit with the adjacent tooth structure providing an area for oral bacteria to adhere and grow/
• Minor cracks or gaps in the fillings may allow bacteria to enter the tooth, leading to decay from beneath the filling
• If the patient has not improved the oral care and dietary habits that led to the initial tooth cavities, the recurrence of tooth decay in the same or other teeth is highly possible.

Dental Braces

One of the main concerns when wearing dental braces is the maintenance of good oral hygiene. The areas of teeth around dental braces and under arch-wires are very difficult to clean. Many patients fail to completely remove dental plaque initiating the demineralization process of tooth decay. In most cases the amount of time wearing braces is not enough for the formation of cavities (holes in the enamel) and the damage is reversible. The most usual indication of tooth decay damage caused by braces are white spots on teeth when the braces are removed.

Gum Recession – exposed roots

The main indication of receding gums are the exposed tooth roots. The root part of a tooth is not protected by hard tooth enamel as the crown of the tooth. The root has only a thinner layer of ‘cementum’, a material softer than enamel, to cover the soft tooth material underneath (dentin). The vulnerable softer root surface can be affected by acids much easier than the rest of the tooth. This fact in combination with the difficulty of perfectly cleaning across or under the gum line, make receding gums another common cause of tooth decay (root decay).

Age

• Babies – A common cause of tooth decay in babies is baby bottle tooth decay (early childhood caries), which occurs when a child goes to sleep with a milk or juice bottle in the mouth, exposing teeth to a high sugar environment for an extended period of time.
• Elderly – The elderly are more susceptible to dental caries mainly due to the reduced flow of saliva either as a result of normal aging or as a complication of medications they have to take or systemic diseases. Gum recession that exposes vulnerable tooth roots is also common in older age. Exposed roots in combination with less saliva to neutralize acids and declining manual dexterity in toothbrushing make the elderly more susceptible to root cavities.

Systemic Diseases

Several systemic conditions may have symptoms that cause tooth decay as a complication. These usually include either reducing the levels of saliva or increasing the acidity of the mouth.

• Diabetes - People who suffer from diabetes are in increased risk of gum disease and dental caries.
• Gastroesophageal reflux disease (GERD) - GERD or acid reflux, is a condition in which the liquid acidic content of the stomach regurgitates (refluxes) into the esophagus. In some cases the acid can enter the mouth and erode the teeth surfaces.
• Cyclic vomiting syndrome – is a condition that causes recurring attacks of severe nausea and vomiting in children that can last for days.
• Respiratory conditions - such as allergic rhinitis, which cause you to breathe through your mouth, drying it out.
• Sjogren's syndrome - is an autoimmune disorder in which immune cells attack and destroy the glands that produce tears and saliva.
• LADD syndrome - Lacrimo-auriculo-dento-digital syndrome is an extremely rare genetic disorder characterized by abnormalities affecting the salivary glands.

Medicines

• Some medicines contain sugar that could promote tooth decay in the presence of dental plaque.
• Use of medicines such as some antidepressants, antiepileptic medicines, beta-blockers etc. can cause reduction of saliva production

Smoking

Smokers have a higher chance of developing tooth decay as the tobacco smoke reduces the production of saliva.

Excessive teeth whitening

Frequent home tooth bleaching or professional tooth whitening can weaken tooth enamel and make it easier for acids to cause tooth decay and cavities.

Tooth abrasion – Tooth erosion

• Acidic drinks can cause irreversible loss of minerals from the tooth enamel (tooth erosion). Brushing immediately after drinking acidic drinks can actually increase even more the level of damage.
• Aggressive brushing with a hard bristled toothbrush may damage tooth’s enamel in the long term making it more vulnerable to acids.
• Bruxism habit (teeth grinding and clenching) can damage the enamel. Acids can easier penetrate the weakened enamel and cause severe tooth decay.

Eating disorders side-effect

• Bulimia nervosa, often simply called bulimia, is an eating disorder characterised by first consuming large amounts of food and then trying to prevent the body to absorb the excess calories by self-induced vomiting, use of laxatives or excessive exercise. Vomitting associated with bulimia can be a basic cause of dental caries, due to the highly acidic environment it creates in the mouth. (acids in vomit can dissolve the tooth enamel)
• Anorexia, is another eating disorder that may also be one of the causes of tooth decay because it may interfere with saliva production.

Drug addiction

• Crystal meth – methamphetamine addicts have a combination of drug induced symptoms and behavior patterns that cause severe tooth decay and gum disease. The condition is known as ‘meth mouth’
• Heroin and other narcotics – narcotic drugs addicts are susceptible to serious decay in their teeth due to a relentless ‘sweet tooth’. These drugs stimulate an addiction to sugary soft drinks and candy which causes increased incidences of dental caries.

Female sex hormones levels

Several studies have shown that high levels and fluctuations of female estrogens are related with increased cavity rates, either inducing tooth decay directly or by dietary changes that promote dental caries.