Editing Tooth decay (section)

===Bacteria===
[[File:Streptococcus mutans 01.jpg|right|thumb|alt=Refer to caption|A [[Gram stain]] image of ''Streptococcus mutans'']]{{See also|Oral ecology}}
The most common bacteria associated with dental cavities are the mutans streptococci, most prominently ''[[Streptococcus mutans]]'' and ''[[Streptococcus sobrinus]]'', and [[Lactobacillus|lactobacilli]]. However, cariogenic bacteria (the ones that can cause the disease) are present in dental plaque, but they are usually in too low concentrations to cause problems unless there is a shift in the balance.<ref>{{Cite journal|last1=Marsh|first1=Philip D.|last2=Head|first2=David A.|last3=Devine|first3=Deirdre A.|year=2015|title=Dental plaque as a biofilm and a microbial community—Implications for treatment|url=https://www.sciencedirect.com/science/article/abs/pii/S1349007915001073|journal=Journal of Oral Biosciences|volume=57|issue=4|pages=185–191|doi=10.1016/j.job.2015.08.002|s2cid=86407760|archive-url=https://web.archive.org/web/20210829091308/https://www.sciencedirect.com/science/article/abs/pii/S1349007915001073|archive-date=29 August 2021}} [http://eprints.whiterose.ac.uk/88879/ Alt URL] {{Webarchive|url=https://web.archive.org/web/20210508033258/https://eprints.whiterose.ac.uk/88879/ |date=2021-05-08 }}</ref> This is driven by local environmental change, such as frequent sugar intake or inadequate biofilm removal (toothbrushing).<ref>{{Cite journal|last=Marsh|first=P|year=1994|title=Microbial ecology of dental plaque and its significance in health and disease|journal=Advances in Dental Research|volume=8|issue=2|pages=263–71|doi=10.1177/08959374940080022001|pmid=7865085|s2cid=32327358}}</ref> If left untreated, the [[disease]] can lead to pain, [[tooth loss]] and [[infection]].<ref>[http://www.mayoclinic.com/health/cavities/DS00896/DSECTION=7 Cavities/tooth decay] {{webarchive|url=https://web.archive.org/web/20080315144137/http://www.mayoclinic.com/health/cavities/DS00896/DSECTION%3D7 |date=2008-03-15 }}, hosted on the Mayo Clinic website. Page accessed May 25, 2008.</ref>

The mouth contains a wide variety of [[oral ecology|oral bacteria]], but only a few specific species of bacteria are believed to cause dental caries: ''Streptococcus mutans'' and ''Lactobacillus'' [[species]] among them. ''Streptococcus mutans'' are gram-positive bacteria which constitute biofilms on the surface of teeth. These organisms can produce high levels of lactic acid following [[fermentation]] of dietary sugars and are resistant to the adverse effects of low pH, properties essential for cariogenic bacteria.<ref name="Hardie1982"/> As the [[cementum]] of root surfaces is more easily demineralized than enamel surfaces, a wider variety of bacteria can cause root caries, including ''[[Lactobacillus acidophilus]]'', ''[[Actinomyces|Actinomyces spp.]]'', ''[[Nocardia spp.]]'', and ''Streptococcus mutans''. Bacteria collect around the teeth and gums in a sticky, creamy-coloured mass called [[dental plaque|plaque]], which serves as a [[biofilm]]. Some sites collect plaque more commonly than others, for example, sites with a low rate of salivary flow (molar fissures). Grooves on the [[Occlusion (dentistry)|occlusal]] surfaces of [[molar (tooth)|molar]] and [[premolar]] teeth provide microscopic retention sites for plaque bacteria, as do the interproximal sites. Plaque may also collect above or below the [[gingiva]], where it is referred to as supra- or sub-gingival plaque, respectively.

These bacterial strains, most notably ''S. mutans'', can be inherited by a child from a caretaker's [[kiss]] or through feeding [[premastication|pre-masticated]] food.<ref>{{citation |journal=Pediatric Dentistry|date=Sep–Oct 2008 |volume=30 |number=5 |pages=375–87 |title=Association of mutans streptococci between caregivers and their children |last1=Douglass |first1=JM |last2=Li |first2=Y |last3=Tinanoff |first3=N.|pmid=18942596 }}</ref>