Bacteria and poor dental hygiene practices are often listed as causes for cavities and tooth decay. While this is true in many individuals, some people find that despite their best efforts at brushing and no matter how frequently they floss, they still are left with cavities. Researchers at the University of Zurich have found a possible explanation for this, and it starts in the DNA.
Specifically, Swiss scientists at the Centre of Dental Medicine and the Institute of Molecular Life Sciences have found that it starts in the DNA gene complex that is the foundation for the formation of tooth enamel. Tooth enamel is the hard, bony white substance that covers the tooth. It is the hardest substance in the body, and it serves to protect the sensitive, living parts of the tooth from bacteria and food debris during chewing.
These researchers examined mice with enamel protein mutations and found that three of these mutations are responsible for sending incorrect signals in the WNT signaling pathway. This pathway allows genes to respond to stimuli and activate the cells they are intended to be. When the stimulus to activate does not arrive as it should, cells become malformed or do not form at all. It is an important function for the growth of cells, and pathway mutations are responsible for diseases and even disorders that cause physical malformations. In this study, researchers found that all of the mice examined with this enamel protein mutation, enamel deformities did exist.
Such enamel deformities include soft enamel and enamel that is structurally weak compared to normal tissue. When the enamel is soft or weak, decay-causing bacteria easily begin eating away at the tissue. Cavities form and patients, despite their best attempts at oral hygiene, are left needing restorations to stop further decay from damaging the teeth. These restorative treatments traditionally include fillings, root canals and crowns, and in many cases come along with a whole new set of concerns.
"Traditional restorations fail for several reasons," Dr. Steven P. Rogers, a Grant’s Pass, Oregon, dentist. said.
One of these reasons is that decay-causing bacteria are not fully eradicated at the time of treatment, and some slip under the restoration, causing further decay from the inside out. Another reason is the traditional restorations simply do not function like normal enamel. This stress causes repairs to move, crack or fall out, which may lead to complete tooth loss.
"Materials like metal amalgam do not bond with the tooth’s enamel, and every time force is exerted on that restoration through normal actions like biting and chewing, it creates stress," Rogers said. "The risk of restoration should not be losing your teeth."
Rogers practices biomimetic dentistry, a method that uses materials that are similar to tooth enamel to restore areas decay. These materials tightly bond with the tooth, sealing out decay-causing bacteria. The tooth is left stronger, and biomimetic restorations have been known to last considerably longer than traditional restorations.
"The average expected lifespan of a traditional dental crown is about five years," Rogers said. "Biomimetic restorations have been going strong for over a decade."
Rogers is excited about the findings of this Swiss study, and any study that leads to innovations in treating tooth decay.
"The more that science can uncover about why tooth decay occurs allows research to refine better methods and products to help in the treating, and hopefully stopping, tooth decay," he said.
In the meantime, Rogers encourages patients to continue to practice good dental hygiene by brushing at least twice per day, and flossing at least once per day.