Oral Health, Wrigleys

Oral health benefits of sugarfree gum

Abstract

The use of sugar-free gum provides a proven anti-caries benefit, but other oral health effects are less clearly elucidated. Chewing sugar-free chewing gum promotes a strong flow of stimulated saliva, which helps to provide a number of dental benefits: first, the higher flow rate promotes more rapid oral clearance of sugars; second, the high pH and buffering capacity of the stimulated saliva help to neutralise plaque pH after a sugar challenge; and, lastly, studies have shown enhanced remineralisation of early caries-like lesions and ultimately prospective clinical trials have shown reduced caries incidence in children chewing sugar-free gum.

This paper reviews the scientific evidence for these functional claims and discusses other benefits, including plaque and extrinsic stain reduction, along with the possibility of adding specific active agents, including fluoride, antimicrobials, urea and calcium phosphates, to enhance these inherent effects. The evidence for a specific effect of xylitol as a caries-therapeutic agent is also discussed.

In conclusion, it is asserted that chewing gum has a place as an additional mode of dental disease prevention to be used in conjunction with the more traditional preventive methods.

Introduction

The oral health, particularly caries-reducing, benefits of sugar-free chewing gums have been well documented in many studies and reviews (1-6). In addition, chewing gum is increasingly being viewed as a delivery system for active agents that could potentially provide direct oral care benefits. The purpose of this paper is to provide an overview of the use of chewing gum as an adjunct to other oral health prevention strategies, reviewing the scientific support for these claims, along with some insights into the chewing gum industry, allowing the interested dental practitioner to stay informed and to be able to answer patients’ questions as they arise.

Use of active agents in chewing gums

Imfeld reviewed the literature on dental benefits of chewing gum in 1999 and concluded that chewing gum was a feasible delivery system for a number of therapeutic agents (4). Despite this, there are a number of factors that potentially limit the incorporation of pharmaceutically active products into chewing gum, including consistency of release, regulatory constraints and consumer acceptance.

Release and formulation issues

Traditional chewing gum is a blend of gum base, flavourings and colourings, preservatives, sweeteners and softeners. The gum base component is a mix of high molecular weight polymers, rubbers and other substances, which facilitates prolonged chewing, but also gives gum a lipophilic character, which can limit release of hydrophobic compounds.

During chewing, gum is hydrated and softened by saliva, and the soluble components, such as the bulk sweeteners, are mostly released within the first five minutes, whereas strongly lipophilic substances release more slowly, with extended chewing releasing less than 50% of the loaded amount, limiting the ability of gum to deliver precisely metered dosages of highly lipophilic active ingredients. In addition to release concerns, the stability of actives or ingredients during processing and shelf life needs to be confirmed. Therefore it is crucial, when formulating chewing gum with active ingredients, to understand the factors that could influence release of actives and to monitor the kinetics of release of the product, and pharmacokinetics where appropriate, to determine uptake. The best approach to monitoring the release of actives would be to compare loading levels to levels remaining in the gum cud after different periods of chewing, and preferably also in saliva, to determine the mass balance over the duration of the chewing period.

Regulatory issues

Chewing gum is regulated as a food by the US Food and Drug Administration, European Union (EU) food law and most other regulatory agencies around the world. As such, most commercial chewing gum is made according to food good manufacturing practices (GMP) and the marketing, distribution and sales of the product are regulated accordingly. Depending on the country or region, it may be possible to have gum regulated as cosmetic, over-the-counter drug, prescription drug, or medical device for specific formulations or claims. The addition of fluoride, chlorhexidine or other actives with undisputed efficacy against oral diseases would require that the product be manufactured to drug GMP in factories certified for this type of production, with rigorous monitoring by the relevant local regulatory agencies.

Although all of this is possible, and there are examples of medicated chewing gums containing active agents such as aspirin and nicotine, most chewing gum is sold as a food or confection, with a price structure and business model that relies on low cost and high volume. Similarly, it is possible for a product to be classified as a drug, depending on the claims made, while approved disease risk reduction claims may be allowable for some foods, in many cases the mere mention of a therapeutic effect (for example, plaque reduction) would drive the product into the drug category. Since 2007, companies or organisations wishing to make a health claim on food products sold in the EU have been required to submit scientific dossiers of supporting evidence to the European Food Safety Authority (EFSA). This is a rigorous review process intended to protect consumers from being exposed to misleading or fraudulent health claims associated with specific foods. Claims are allowed pertaining to three general categories under EU law:

1. Article 13.1 claims, referring to the role of a nutrient or other substance in the growth, development and function of the body, based on generally accepted scientific evidence

2. Article 13.5 claims, referring to the role of a nutrient or other substance in the growth, development and functions of body, based on newly developed scientific evidence and/or proprietary data and

3. Article 14 claims, referring to disease risk reduction or children’s development/health.

To date, six chewing gum-specific claims have received positive opinions, while six others have not been approved (Table 1).

While these regulations dictate what consumer claims can currently be made, there is a general understanding that health professionals, with more in-depth understanding of the science, can interpret the impact of other benefits. For example, most dentists would agree that a reduction in oral Mutans Streptococcus (MS) counts would be a positive oral health outcome, but without direct evidence that such an isolated effect would have an impact on caries incidence, this would not be an allowable claim under EFSA regulations.

Table 1: Chewing gum claims reviewed by the European Food Safety Authority, as of September 2012: Article 13(1) – health claims pertaining to the effects of nutrients or other substances in the growth, development and functions of the body; and, Article 14 claims – reduction of disease risk claims and claims referring to children’s development and health. For precise working on claims, refer to EFSA website – www.efsa.europe.eu/.

Approved

Not approved

Sugar-free chewing gum contributes to the neutralisation of plaque acids

Sugar-free chewing gum reduces plaque formation

Sugar-free chewing gum contributes to the maintenance of tooth mineralisation

Sugar-free chewing gum sweetened with xylitol helps to reduce plaque

Sugar-free chewing gum contributes to the reduction of oral dryness

Sugar-free chewing gum sweetened with xylitol is good for the health of the ears

Sugar-free chewing gums with carbamide neutralises plaque acids more effectively than sugar- free chewing gums without carbamide

Sugar-free chewing gum with pyro- and triphosphates reduces calculus formation

Chewing gum sweetened with 100% xylitol has been shown to reduce dental plaque. High content/level of dental plaque is a risk factor in the development of caries in children (Article 14)

Sugar-free chewing gum with calcium phosphoryl oligosaccharides  helps to maintain tooth mineralisation

Sugar-free chewing gum with fluoride increases the resistance of enamel to acid attacks and the rate of remineralisation (based on delivering 0.75mg F per day; number of servings/day not stipulated)

Gum Periobalance lozenge and chewing gum with the active ingredient Lactobacillureuteri rebalances the oral microflora and improves oral health

Consumer acceptance

While most consumers purchase and chew gum for the enjoyment of an affordable, pleasurable, sensory experience, the addition of specific and supportable health benefits, particularly around the established oral health benefits of saliva stimulation and plaque pH neutralisation, provides them with an additional reason to chew. However, consumer research has consistently shown that a pleasant sensory experience is non-negotiable and most consumers will not chew a product with an unpleasant flavour, oral side effect, aftertaste, or that adversely affects taste perception. Likewise, there are two other aspects of the consumer experience that need to be considered; namely, cost and believability. While consumers may not want to pay too much for a pack of gum, if a product with associated health claims does not come at a premium price, they may not believe the claims.

Chewing gum as a drug delivery system offers some attractive consumer benefits, such as portability, relatively rapid onset of action, and ability to swallow easily without water. Specific powdered gum formulations are commercially available to allow the pharmaceutical industry to manufacture gum using existing tableting technology as an alternative product form. Selected pharmaceutical ingredients can simply be incorporated into the product, or encapsulated in suitable carrier systems as required if stability, taste or compatibility with the gum matrix are problematic. For some drugs oral mucosal absorption could allow more rapid uptake and pharmacokinetic studies of both nicotine and caffeine gums suggest that this pathway results in relatively rapid (and in the case of nicotine, prolonged) plasma levels being reached by bypassing the stomach and first pass liver metabolism (7, 8). However, the added benefits of using chewing gum as a pharmaceutical delivery system are only realisable as long as the organoleptic properties of the product encourage patient compliance with dosing.

While chewing gum may not be an ideal drug delivery system for general or systemic health, the fact that it is consumed in such a way that the product is in contact with the oral tissues for a prolonged period provides the possibility of pursuing specific topical benefits of chewing gum actives on the mouth and dental hard tissues. These could include prevention or removal of biofilm, improved remineralisation or caries protection, anti-gingivitis or other effects.

These benefits will be summarised in the remainder of this article.

Non-specific benefits of chewing sugar-free gum: Oral clearance and saliva stimulation, plaque pH neutralisation

The major benefits of sugar-free chewing gum are mediated through oral physiology: Stimulation of the salivary glands to produce a strong flow of saliva (a 10-12 fold increase over unstimulated saliva) is elicited by a combination of masticatory and gustatory stimuli (9). Although saliva flow rates are highest during the first five to seven minutes of chewing, when the sweeteners and flavour release is maximal, a twofold increase in flow rate (over unstimulated flow) is maintained for as long as the gum continues to be chewed (10).

One of the immediate short-term effects of this enhanced saliva flow is the increased clearance of sugars and food debris from the oral cavity (11). The higher flow rate, pH and buffer capacity of stimulated saliva further help to neutralise acids found in the mouth and, in particular, help to raise the plaque pH, accelerating the recovery phase of the Stephan curve (12, 13). The short-term neutralisation of plaque pH out of the demineralisation danger zone can also be supplemented by medium-term benefits, as it has been shown that frequent chewing increases baseline (unstimulated) saliva flow rate and increases the resting plaque pH and subsequent ability of the plaque to form acid from sugar (14, 15). Some studies have suggested that chewing gum is better tolerated than artificial saliva for symptomatic relief of xerostomia (16, 17).

Remineralisation and clinical caries reduction

In addition to the pH neutralising effect, the increased rate of delivery of soluble calcium and phosphate ions from the stimulated saliva helps to remineralise surface enamel lesions, as shown in a number of in situ remineralisation studies (18-21). Finally, clinical studies conducted in children who chewed gum at least three times daily for two or three years show that they have significantly lower rates of decay than children who do not chew gum (22-24). Furthermore, these caries-reducing effects have been confirmed by systematic reviews (2, 5 and 25). Indeed, the American Dental Association has recently provided clinical guidelines for the use of sucrose-free polyol chewing gums in highcaries- risk children and adults (25).

Extrinsic stain reduction

Chewing gum can reduce extrinsic tooth stain, either by removing existing stain or inhibiting its formation (26), while the addition of specific active agents (typically polyphosphates) may provide additional efficacy (27, 28). However, it should be noted that these types of claims are cosmetic and do not directly affect oral health, and the magnitude of the effect is small compared to chair-side or over-the-counter bleaching therapies. On the other hand, accelerated oral clearance of staining agents such as tea or coffee, by chewing gumstimulated saliva, could conceivably reduce the formation of extrinsic stain over time and help to prolong the benefits of a dental prophylaxis. Interestingly, chewing gum has been found to counteract the short-term sensitivity associated with professionally applied bleaching treatments (29), although the mechanism of this effect is not clear. On a related note, some orthodontists use chewing gum to help distract patients from the discomfort associated with placement or tightening of bands or appliances. This effect was confirmed in a recent study that measured patients’ responses on the impact of the fixed orthodontic treatment and found that those who chewed gum reported decreased intensity of pain 24 hours after the treatment (30).

Effects on plaque and gingivitis

There is evidence that regular use of chewing gum, in conjunction with normal oral hygiene procedures, provides a slight, but significant, reduction in plaque scores (31-33), although one other study did not show this effect (34). In addition, two of these studies showed effects on inflammatory parameters, such as bleeding score or gingival index (32, 33).

Interestingly, the EFSA did not approve claims on plaque reduction from chewing gum, although this may be due to the fact that the submission did not effectively distinguish between studies that looked at chewing with or without normal oral hygiene. While there is evidence from some studies that chewing gum in the absence of other routine oral hygiene measures can reduce plaque accumulation, it has been argued that most of the reduction occurs at occlusal sites and is therefore not relevant to prevention of gingivitis (35). A recent systematic review concluded that chewing sugar-free gum provides a small but significant reduction in plaque scores when used as an adjunct to normal plaque control measures (36). Therefore, any claims regarding effects of sugar-free gum without actives on plaque should be interpreted only as a potential adjunctive effect, not intended to substitute chewing gum as an alternative to regular brushing and flossing.

Active agents for remineralisation/caries

There have been many attempts to improve the inherent remineralising effect of chewing gum-stimulated saliva through the addition of specific active ingredients. These actives include: specific polyols, urea, fluoride, established antimicrobial agents (such as chlorhexidine, CPC or Triclosan), enzymes, natural bioactives (including antioxidants and various polyphenols), probiotics and calcium salts, including calcium phosphates and novel calcium substances, such as casein phosphopeptide-amorphous calcium phosphate (CPP-ACP).

Specific polyol effects – is xylitol a magic ingredient?

Sugar-free gums are usually sweetened with polyol (sugar alcohol) sweeteners, such as sorbitol, mannitol, xylitol or maltitol and blends of these are used to provide the required physical processing, cost and organoleptic properties of the final product.

These polyols have all been certified as safe for teeth by appropriate plaque pH testing; thus, while their inherent sweetness helps to stimulate saliva, their rate of metabolism and acid production by the oral (plaque) bacteria is slow and does not cause an effective drop in the plaque pH, so the net effect is an increase in the plaque pH.

There has been considerable research to test whether certain polyols show superior efficacy. One specific example is xylitol, a five-carbon polyol sugar, which cannot be metabolised by the acid-forming bacteria in the dental plaque. Although in theory this should confer some advantage for xylitol as a sweetening agent, clinical data confirming the superior efficacy of xylitol over other polyols in chewing gum for prevention of plaque, reduction of plaque acidogenicity, and decreased caries incidence are contradictory. Table 2 is a summary of chewing gum studies that allows for direct comparisons between xylitol and other polyol (predominantly sorbitol) sweeteners. To summarise, there is no difference between polyols on short-term plaque pH neutralisation (37), while chronic usage of xylitol was shown to reduce plaque acidogenicity in two studies (38, 39), but not in another two (40, 41). There appears to be a more consistent effect of xylitol gums on suppressing salivary MS counts (42, 43), while one recent study showed suppression of plaque MS from caries-prone interdental sites (44). On the other hand, in situ remineralisation studies have not found any significant differences in the amount of mineral found in the enamel samples after chewing with sorbitol- or xylitol/sorbitol-sweetened gums (21, 40). A total of four double-blind caries clinical trials of xylitol chewing gum versus other polyol- (sorbitol) sweetened gums have been conducted. Three showed no differences between xylitol and sorbitol gums in terms of new caries development (23, 45, 46), while one study showed an advantage for the xylitol-sweetened gums (47). Thus, despite the impression that xylitol may confer specific dental health advantages over other polyol sugars, the clinical evidence for this is equivocal. Similarly, previous reviews on the topic have provided mixed conclusions, in some cases favourable (1), in others equivocal (2) and in other cases negative (48-50). Since the efficacious dose range for xylitol consumption has been determined to be 6-10g per day based on data showing suppression of salivary Streptococcus mutans counts (51), it is possible that some of the studies showing no superiority of xylitol over other polyolsweetened gums failed to provide the required dosage. Indeed, of the previously mentioned caries clinical trials, only two achieved this minimum dosage (46, 47). Thus, the evidence is that xylitol in chewing gum may help to reduce salivary MS counts and, in some cases, slightly reduce plaque acidogenicity, but the clinical data for a superior remineralisation or caries-reducing effect are not consistent. Notably, the EFSA has only approved one xylitol claim for chewing gum, which is that chewing gum sweetened with 100% xylitol may reduce caries risk in children.

Interestingly, erythritol, a four-carbon polyol sugar, has been shown to be as effective, if not more effective, than xylitol in reducing caries-associated factors. After six months of six-times-daily use of erythritol tablets, saliva and plaque levels of Streptococcus mutans were reduced, and clinical plaque scores were also lower in the erythritol and xylitol groups (52), although whether this is a specific effect of the polyol itself remains to be confirmed.

Fluoride chewing gum

Fluoride has been added to chewing gum and claims for its use in chewing gum have been approved by the EFSA. However, relatively few studies have been conducted on the remineralisation effect of fluoride-containing gums and most of these were in small groups who also used fluoride-free dentifrices (53, 54). A larger (N=15) in situ remineralisation study, which also specifically excluded use of fluoride dentifrice, failed to show an overall difference in remineralisation parameters between fluoride-containing and placebo gums (55).

Thus, despite the positive review by the EFSA, the present evidence does not support a clear anti-caries benefit of putting small amounts of fluoride in chewing gum, and regulatory and safety concerns further weaken this position.

Table 2: Overview of design anresults of studies that have compared xylitol in chewing gum directly to other polyol sweeteners.

Study

Type of study

Groups

Experimental design*

Summary of findings

Aguirre-Zero 199338

Plaque pH

No gum, Sucrose gum, Sorbitol gum, Xylitol gum

N=10; two weeks’ gum use, 5x daily; Plaque pH response to sucrose measured after treatments

Decreased plaque pH response to sucrose after two weeks’ xylitol gum

Söderling 198939

Plaque pH

Sucrose gum, Sorbitol gum, Xylitol gum, Sorbitol/xylitol gum

N=7; two weeks’ gum use, 5x daily; plaque pH response to sucrose measured following pre-rinse with polyol solution corresponding to gum group

Decreased plaque in xylitol groups; minimum plaque pH to sucrose higher in xylitol groups

Park 199537

Plaque pH

Five commercial gums with different sweeteners, no gum and paraffin

N=8; plaque pH response to sucrose measure followed by chewing one of five gums

All sugar-free gums raise plaque pH after sucrose rinse – no differences are under pH curve between groups

Wennerholm 199440

Plaque pH In situ remineralisation

Xylitol gum, Sorbitol gum, 50:50 xyl:sorb, 25:75 xyl:sorb

N=17; 25 days’ gum use, 12x daily; plaque pH response to sucrose and sorbitol; salivary and plaque MS; enamel mineral content

No differences in plaque pH response to sucrose; plaque pH response to sorbitol decreased with increasing xylitol gum content; no differences in mineral loss between groups

Scheie 199841

Plaque quantity and acids

Xylitol gum, Xylitol/sorbitol gum, Sucrose gum

N=30; 33 days’ gum use, 5x daily; plaque collected, analysed for quantity and ex vivo acid production

No differences between groups in plaque quantity or acidogenic potential

Hildebrandt 200042

Oral MS counts

No gum, Sorbitol gum, Xylitol gum

N=46-48; three months’ gum use, 3x daily, following two weeks’ CHX treatment; salivary MS counts measured before and after treatments

Xylitol gum helped to maintain suppression of salivary MS, significantly lower than control or sorbitol gum

Manning 199221

In situ remineralisation

Xylitol gum, 25:75 xyl:sorb gum

N=9; two weeks’ gum use, 5x daily; enamel mineral content

No differences in mineral gain (remineralisation)

Campus 200943

Plaque pH Salivary MS

Polyol blends: xylitol gum (50%); no xylitol

N=204; six months’ gum use, 5x daily; salivary MS and plaque pH response to sucrose at baseline, one, three and six months, and three months after cessation

Higher pH minimum after sucrose rinse at three and six months, xylitol vs. control gum; lower salivary MS at three and six months

Söderling 201144

Total salivary bacteria, LB and MS; plaque MS

Xylitol gum, Sorbitol gum

N=12; four weeks’ gum with crossover

Xylitol gum reduced plaque MS counts from caries-prone (interdental) sites; no other effects noted

Kandelman 199045

Clinical caries study

No gum, Low xylitol gum, High xylitol gum

N=274; age eight to nine; two years’ gum use, 3x daily (school days only)

Both xylitol groups had lower DMFS increment than control, with no differences between gum groups

Machiulskene 200123

Clinical caries study

No gum, Control gum (HIS) Xylitol gum, Sorbitol gum (sorbitol gum with urea)

N=432; age nine to 14; three years’ gum use, 5x daily

Two-year DMFS increments significantly lower in sorbitol group; three-year DMFS increments showed no differences between control, xylitol and sorbitol groups; sorbitol/urea gum group had higher increment than other gum groups

Mäkinen 199547

Clinical caries study

Nine groups: control; four xylitol gums; two xylitol/sorbitol gums; sorbitol gum; sucrose gum

N=1135; age 10; 40 months’ gum use, 3-5x daily

Sorbitol gum reduced caries rates, but not as effectively as xylitol gums, with the xylitol pellet gum consumed five times daily being significantly better than any other gum

Mäkinen 199646

Clinical caries study

Seven groups: control; two xylitol gums (stick, pellet); two xylitol/sorbitol groups (pellets, low and high xylitol:sorbitol ratios); two sorbitol gums (stick, pellet)

N-427; age six; 24 months’ gum use, 5x daily

All gums reduced caries incidence; 100% xylitol pellet gum was most effective, sorbitol stick least; otherwise there were no differences between the groups

* Wheindicated, N refers to number of subjects at end of study, and age is age at study initiation; MS = Mutans Streptococci; LB = lactobacilli.

Calcium and phosphate salts

Other approaches to improving the inherent anti-caries effect of sugar-free gums have focused on the use of suitable calcium or calcium phosphate salts to supplement the natural calcium and phosphate levels of saliva, raising the level of saturation of the immediate tooth environment with respect to these ions to aid remineralisation (56, 57). Calcium lactate added to chewing gum has also been shown to provide an enhanced remineralisation benefit (58, 59).

The clinical evidence for a superior remineralising/anti-caries effect of casein-calcium conjugates, such as CPP-ACP, has previously been reviewed (60-63). Based on these reviews there is still no scientific consensus that CPP-ACP provides superior remineralisation benefits in a chewing gum delivery system, and the published in situ chewing gum studies have, for the most part, relied on a methodology that has been criticised (62). Therefore, while CPP-ACP shows promise as a remineralising agent in topical pastes, creams and rinses (60, 63), its efficacy in chewing gum requires confirmation by independent research groups (61).

Urea (carbamide)

Urea has been approved by the EFSA for claims that it helps to neutralise plaque pH more effectively than regular sugar-free gum, although the clinical research findings on the addition of this ingredient to chewing gum are equivocal. Some studies showed that urea-containing gums helped to neutralise plaque pH more effectively than placebo gum (64, 65), while others found no differences in terms of either plaque pH response after sugar challenge or extent of remineralisation in subjects who chewed either urea or placebo gums for four weeks (55, 66). Finally, a three-year clinical intervention study showed no benefit of chewing gum with urea compared to either sorbitol, xylitol or non-polyol gums (23); in terms of raw DMFS data, the urea gum group had significantly higher caries increments than all other groups, except the no gum group.

Antimicrobials

Chlorhexidine, Triclosan, CPC

A number of studies of chlorhexidine (CHX) gum and plaque/gingivitis have been undertaken and most have demonstrated significant plaque and gingivitis-reducing effects of the CHX gums (67, 68). However, as described earlier, there may be regulatory and consumer acceptance issues with marketing a chewing gum with a strong antimicrobial agent, especially one where there is a known taste issue. Therefore, CHX gums may be indicated for certain highrisk groups, but they would not be available as over-the-counter gum products for the general public. Similar concerns exist for other known antimicrobial agents, such as Triclosan and CPC, while there is also concern about long-term antimicrobial usage affecting the commensal oral and gut flora.

Natural antimicrobials

Magnolia bark extract

Magnolia bark extract (MBE) is a natural extract and traditional Chinese medicine, consisting mainly of the phenolic isomers magnolol and honokiol.

Following the finding that MBE reduces salivary bacterial counts (69), we showed significant reduction of in vitro biofilm growth with this active, as well as in vivo reduction of salivary Mutans Streptococci and plaque following longer term gum usage (70-72). More recently, MBE gum reduced oral MS counts and plaque acidogenic response to a sucrose rinse in 40 subjects after 30 days, chewing three times a day to deliver 11.9mg MBE/day, compared to either xylitol or non-xylitol control gums (73). These results suggest a synergistic effect between MBE and xylitol, as the daily xylitol intake from the gum vehicle was a sub-optimal 2.2g/day.

Other natural substances and probiotics

It is beyond the scope of this paper to provide a comprehensive review of all the natural ingredients that have been tested in chewing gums, but a recent review provides an excellent starting point for determining the potential of such actives to provide a clinical benefit from chewing gum (74). Many of these actives are antimicrobial and have the potential to inhibit biofilm formation and/or activity (for example by inhibiting S. mutans glucosyl transferase), but there are few, if any, clinical studies to confirm that any of these have a caries-preventive benefit.

Probiotic therapy has the potential to provide oral health benefits, through modulation or suppression of oral pathogens, although chewing gum studies are rare and few of these have determined an end point directly relevant to caries. One such study measured salivary counts of lactobacilli and S. mutans in subjects who consumed probiotic gum, xylitol gum, xylitol gum with probiotic, or placebo for three weeks (75). While both probiotic and xylitol gum groups showed significant reductions in S. mutans scores, the combination of probiotics and xylitol had no effect, suggesting a negative interaction between the two. Recent EFSA opinions on probiotics for systemic health in general have not been favourable and the oral health claim for L. reuteri was also not approved.

Potential negative effects of chewing gum

It is worth acknowledging that there are some concerns over chewing gum use, including its potential to be a choking hazard in young children, be subject to littering, exert a laxative effect and to contribute to temporo-mandibular dysfunction (TMD). Therefore, consumers should be reminded not to give gum to children younger than school age and to dispose of chewed gum responsibly. Although a significant part of our research and development programme focuses on creating a gum base that is less adhesive and/or more degradable if improperly disposed, even with technical advances, the most effective and the only total solution to littered gum is for people to dispose of their used gum responsibly by putting it in a bin. The laxative threshold of most polyol sweeteners used in gum is typically more than 15g/day, which would require consumption of 10 or more sticks of chewing gum per day to achieve. In fact, this effect has been used to help bowel function recovery following abdominal surgery (76). Despite limited evidence that chewing gum is a causative agent of TMD or jaw muscle pain (77), the prudent practitioner should probably avoid recommending chewing gum for patients suffering from these conditions.

Conclusions

As mentioned earlier, the scientific evidence supporting the non-specific benefits of chewing sugar-free gum has been reviewed and endorsed by the EFSA. Traditionally, preventive dentistry has focused on sugar restriction, plaque removal/oral hygiene, fluoride usage, fissure sealants and education. More recently, these approaches have been modified by improved diagnostic methods to allow early identification of disease, together with an accurate assessment of disease activity.

There is an opportunity for chewing gum to be considered as another preventive modality to provide an additional layer of prevention by helping to maintain the oral ecology in high and lower risk individuals and populations. While it is not the intention of this article to provide clinical guidelines for the use of sugar-free chewing gum, the informed practitioner should be able to accurately answer his or her patients’ questions regarding this topic and be able to provide appropriate guidance about this as a possible home use adjunct to the normal oral care regimen, especially in high-risk patients. It is this author’s contention that chewing sugar-free gum provides scientifically and clinically proven oral health benefits that complement other aspects of usual oral care regimens. While chewing gum may not be a treatment for oral diseases, by helping to generate a healthy flow of saliva, it may help to offset the perturbations in the oral ecology that lead to clinical disease states.

References

Please contact seb.evans@fmc.co.uk for a list of references.

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