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Sugar is added to food for a multitude of functions: fermentation, preservation, physical and chemical, and also to satisfy the consumer’s preference for sweetness. Unfortunately, sugar consumption is also a main aetiological factor for dental caries. The relationship between sugar and caries was established in the latter half of the 19th century. Many factors influence this relationship: the availability of sugar for bacterial digestion, the presence of acidogenic bacteria in the plaque on teeth, and the ability of fluoride and saliva to counteract bacteria and acids. The importance of the frequency of administering sugars over the amount has been demonstrated in various studies in humans. Through guidelines, world and national health organizations advocate the reduction of sugar consumption to below 10E% (daily dietary energy percentage consumption per capita), but voluntary implementation on an individual basis is difficult for many, and maybe more compulsory strategies that aim to reduce both the amount and frequency of sugar intake are needed.

Non-restorative cavity control (NRCC) is a 3-part treatment option for dentine cavities in the primary dentition, for root carious lesions and cavitated coronal smooth surface lesions. The first part is that the patient's oral hygiene procedure/habits improve and involve the exposed dentine. For this, it may be necessary to expose the cavity (second part) so that it is accessible for the toothbrush (the lesion exposure method). As long as the dentine carious lesion is diagnosed as active or there is increased risk that carious lesion activity will recur, it is advisable to support the treatment with a 38% silver diamine fluoride (SDF) or a 5% sodium fluoride (NaF) varnish therapy (third part). NRCC has advantages over traditional restorative therapy as it avoids the stress and fear initiation that often results from invasive restorative therapy. It avoids a futile or detrimental repeat restorative cycle when cavity outlines have to be designed in caries active areas and it increases awareness of people's own responsibility for oral health and the quality of the oral hygiene procedure. NRCC has been advocated, particularly in primary dentitions, for patients or parents/carers who are able to accept responsibility for the disease and commit to remedial action including diet modification and regular, frequent toothbrushing with a fluoride toothpaste. It should not be used when immediate invasive action is required such as in the case of pain, infection, or sepsis. Professionals who choose NRCC commit themselves to being critical regarding their educational qualities and to commence a cycle of quality improvement.

Previous studies have shown that Streptococcus oligofermentans inhibits the growth of cariogenic Streptococcus mutans in biofilms in vitro and is considered a probiotic candidate for caries prevention. This study aimed to examine the effects of various environmental factors on the competition between S. oligofermentans and S. mutans in a dual-species biofilm model. Single or dual S. oligofermentans and S. mutans biofilms were grown in a 96-well active attachment model for 48 h. Several growth conditions were examined in the model, namely: S. oligofermentans was inoculated 24 h before S. mutans or vice versa; the growth medium was supplemented with 0.2% sucrose or 0.4% glucose; biofilms were grown under a constantly neutral pH or pH-cycling condition, which included 8 h of neutral pH and 16 h of pH 5.5. The 48-h biofilms were examined for viable cell counts and lactic acid and hydrogen peroxide production ability. When S. oligofermentans was inoculated first, it clearly inhibited the growth of S. mutans and reduced the biofilm lactic acid production by up to 8-fold through hydrogen peroxide production, independently of sugar supply and pH conditions. When S. mutans was inoculated first, the level of inhibition by S. oligofermentans varied depending on the sugar supply and pH conditions. Thus, the inhibition efficacy of S. oligofermentans against S. mutans in dual-species biofilms is influenced by environmental factors. This study provides practical information on how to maximize the efficacy of S. oligofermentans.