Bad teeth are hereditary: myth or reality?

Bad teeth are hereditary: myth or reality?

For centuries people have held the idea that bad teeth are inherited from parents. We have often heard expressions like „already my mother and grandmother had bad teeth“. Dentists refuse to believe these stories. According to a popular theory, only bacteria cause caries. When people hear this from the dentist, they feel guilty. Patients listen to the doctor’s admonitions and recommendations humbly, trying not to blush, but the situation in the mouth still stubbornly fails to improve. Sometimes we see people whose oral hygiene is pretty bad, but teeth are perfectly healthy. So, is it really possible that genes and heredity have no role at all?

Medihub asked the experts what to believe and what not to

One of the best-known scientists in Estonia who has studied caries, professor at the University of Tartu, Reet Mändar said that dental caries is as old as mankind. „Caries is the decay of hard dental tissue, resulting from the activity of bacteria,“ explained professor Mändar. She added that besides famous caries-related bacteria Streptococcus mutans and Streptococcus sobrinus, other acid-producing bacteria affect the process of tooth decay as well.

Useful bacteria help to fight off caries-causing microbes

Professor Mändar emphasized that people have plenty of harmless microbes in the mouth that make up the normal oral microbiota or microflora: „Every person has at least 50–100 different bacterial species living in the mouth and altogether, 700–1000 species have been identified from the oral cavity, most of them being useful or harmless.“ The professor pointed out an amazing fact that some of the bacteria living in the mouth help to fight off caries-causing bad microbes. „A newborn baby gets a set of healthy microbes from his or her mother’s birth canal,“ explained professor Mändar. She added that useful bacteria colonize the child’s mucous membrane lining the oral cavity, start to multiply and later help to fight off caries-related bacteria.

Antibiotics harm the bacteria that fight caries

It means that a fierce battle is being waged in the mouth between different microbes. The defence forces, consisting of good bacteria, fight against foreign invaders and caries-causing microbes. The competition and fight between bacteria makes it even more difficult to determine what exactly causes caries. Professor Mändar brought out some additional possible reasons for having caries, including the effect of antibiotics on good anticaries bacteria: „Other risk factors include decreased salivation, immune deficiency, smoking, a diet rich in sugar, and antibiotics.” The professor mentioned breast-feeding mothers as a separate risk group for getting caries: „The levels of calcium and minerals may decrease in the mother’s organism and that promotes tooth decay.“

Kerti Alev, the CEO of MediKeep: „Dentists tend to stigmatize patients.“

The creator and CEO of the MediKeep application Kerti Alev, who is also an avid protagonist of personal medicine (treatments based on genetic information), helped to bring light on the possible relationship between genes and caries. According to the CEO of MediKeep, this is a long-debated topic: „Dentists tend to stigmatize patients by telling them to just improve their oral hygiene.“ Understandably, the patient feels frustrated and even angry at the doctor. „After all, the patient eats and brushes his or her teeth just as often as the neighbor, but still has caries, while the neighbor enjoys healthy teeth,“ added Alev, explaining a common problem.

Genetic testing will become an integral part of dentistry

According to Kerti Alev, several studies have been conducted, showing that besides bacteria and hygiene, the resistance to caries is dependent on other factors as well. „Several caries-related genes have been identified, most notably CXCR2, AAMP and CXCR1,” said Kerti Alev. „The development of caries is dependent on the strength of tooth enamel, intensity of salivation and content of saliva, and the effectiveness of the immune system; these factors, in their own turn, are genetically determined,“ added Alev. The CEO of MediKeep is convinced that in the future, genetic testing will become an integral part of dental treatment. „This is the essence of personal medicine: based on the genetic profile, a treatment plan and, if necessary, an aggressive prevention plan are drawn up,“ explained Alev.

The president of the Estonian Dental Association: „In reality, bad eating habits are inherited, not bad teeth.“

Doctor Marek Vink, the president of the Estonian Dental Association, explained what dentists think about the topic. The properties of saliva and hard tissues are certainly dependent on genetics, he said, however, in case of having caries, the role of genes is only 20%, and environment- and lifestyle-related factors make up about 70%. „That is why dentists choose not to stress the role of genetics. The myth that everbody in our family has bad teeth can be busted by showing that actually bad eating habits are inherited, not bad teeth,“ explained Marek Vink.

5–10% of people don’t have caries despite bad habits

President Marek Vink added a personal remark that he has been waiting for years for a doctoral student to emerge who would match e-health dental cards and gene donor databases in order to  study what promotes and prevents caries. The president of the dental asociation also brought out an interesting fact that helps to explain why the patients are not equal: „About 5–10% of people have healthy caries-free teeth regardless of what they do.“ However, added Vink, these fortunate few tend to lose their otherwise very healthy teeth due to parodontitis that leads to the falling out of teeth.

The role of genes must not be entirely forgotten

Proper oral hygiene, diet and bacteria are certainly the most important factors affecting the risk of caries, however, the role of genes must not be forgotten as well. Accusing patients of bad hygiene only is an excessive generalization and stigmatization. Hopefully this article helps to start a discussion and spread information.

Contact with the caries-causing bacteria should be postponed as long as possible

Apparently, in the near future, the achievements of genetics and personal medicine will not be available for everyone. Therefore, we have to concentrate on those simple activities that protect us against caries: brushing teeth both in the morning and in the evening, consuming sufficient liquid, following a healthy diet, neutralizing the acidity in the mouth with chewing gum, and using toothpaste with fluoride. It is also very important to postpone infecting children with caries-causing bacteria as long as possible. Thus, sharing a spoon with the child and the practice of cleaning the soother by means of inserting it into your own mouth should certainly be avoided. Breast-feeding mothers must follow a healthy diet and see that they get enough minerals, vitamins and calcium.

For those who have a deeper interest in the topic, here’s the list of references:

  1. GWAS Catalog: https://www.ebi.ac.uk/gwas/search?query=dental%20caries
  2. SNPedia: https://www.snpedia.com/index.php/Dental_caries
  3. Novel caries loci in children and adults implicated by genome-wide analysis of families. https://www.ncbi.nlm.nih.gov/pubmed/29859070
  4. Evidence of a contribution of genetic factors to dental caries risk. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3267319/
  5. A Major Gene Effect Controls Resistance to Caries. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3318028/
  6. Genetic factors affecting dental caries risk: https://www.ncbi.nlm.nih.gov/pubmed/25721273
  7. GWAS of dental caries patterns in the permanent dentition. https://www.ncbi.nlm.nih.gov/pubmed/?term=23064961#
  8. The Caries Microbiome: Implications for Reversing Dysbiosis. https://www.ncbi.nlm.nih.gov/pubmed/29355414
  9. Risk factors for dental problems: Recommendations for oral health in infancy.
    https://www.ncbi.nlm.nih.gov/pubmed/28899616
  10. Effect of erythritol and xylitol on dental caries prevention in children. https://www.ncbi.nlm.nih.gov/pubmed/24852946