Chewing gum and dental health--a review

In vitro remineralization assessment of enamel subsurface lesions using different percentages of surface reaction-type pre-reacted glass-ionomer containing gum-based material

OBJECTIVE

To identify the remineralization activity of enamel subsurface lesions using different percentages of surface pre-reacted glass-ionomer (S-PRG) filler containing gum-base material.

METHODS

Gum extracts from gum-base materials containing 0wt%, 5wt%, and 10wt% S-PRG filler were prepared as GE0, GE5, and GE10, respectively. A total of 50 bovine enamel specimens were used, and the polished enamel surface of a 3 × 3 mm2 window area was exposed. The specimens were then subjected to a demineralization solution for seven days to create a subsurface enamel lesion. Remineralization was then conducted for seven days using a protocol whereby the specimens were immersed three times a day in prepared gum extracts (0wt%, 5wt%, and 10wt%) and artificial saliva of pH 7 (Control) for 20 min at 37 °C. Thereafter, remineralization assessment was performed by using Swept Source Optical Coherence Tomography (SS-OCT) and micro-computed tomography (μCT). Surface morphology and elemental analysis were conducted by scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS).

RESULTS

The depths of the demineralized lesions in the GE5 and GE10 groups were significantly lower than those of the Control and the GE0 groups. SEM observations of the enamel surface morphology of the GE5 and GE10 groups indicated remineralization with S-PRG filler-related elements present.

CONCLUSION

The GE5 and GE10 S-PRG filler containing gum-base materials showed significantly improved surface remineralization and reduced demineralization of the enamel lesions. EDS analysis suggested that the released ions from the S-PRG filler might be responsible for surface remineralization.

CLINICAL SIGNIFICANCE

The S-PRG filler containing gum-base material may have a significant remineralization effect and improve the surface morphology of enamel subsurface lesions.

A Comparative Evaluation of Xylitol Chewing Gum and a Combination of IgY + Xylitol Chewable Tablet on Salivary Streptococcus mutans Count in Children: A Double-blind Randomized Controlled Trial

Aim

The study was designed for evaluation and comparison of the efficacy of Xylitol chewing gum and a combination of IgY + Xylitol chewable tablet (Nodecay ^TM) against the “salivary Streptococcus mutans ” count in children.

Materials and methods

About 120 children belonging to 6-12 years age-group were enrolled into this “double-blind randomized control clinical trial” according to the selection criteria. They were randomly assigned to three groups of 40 each: Group I-Xylitol chewing gum, Group II-IgY + Xylitol Chewable tablet (Nodecay ^TM), and Group III-Control. Children in all the groups had to chew the gum/tablet twice daily for 5 minutes during the 15-day period. The salivary samples at baseline, 15 days, 1, 2, and 3 months were inoculated on mitis salivarius bacitracin agar with potassium tellurite medium and the number of colony-forming units (CFUs) of Streptococcus mutans were determined. The data obtained was subjected to statistical analysis.

Result

There was a “significant” difference in the number of “S. mutans CFUs” amongst the three groups at 15 days, 1st month, 2nd month, 3rd month with highest levels of S. mutans CFUs in Group III-Control and least in Group II-IgY + Xylitol (Nodecay^TM).

Conclusion

The combination of IgY + Xylitol (Nodecay^TM) when administered for 15 days had significant efficacy against “S. mutans” when compared to Xylitol and control group.

Clinical significance

Passive immunization with immunoglobulin Y is known not only to decrease the S. mutans count but also confers extended immunity by preventing recolonization of the tooth surface by persistence of the antibodies in saliva.

How to cite this article

Jain RL, Tandon S, Rai TS, et al. A Comparative Evaluation of Xylitol Chewing Gum and a Combination of IgY + Xylitol Chewable Tablet on Salivary Streptococcus mutans Count in Children: A Double-blind Randomized Controlled Trial. Int J Clin Pediatr Dent 2022;15(S-2):S212-S220.

Effect of encapsulation and wall material on the probiotic survival and physicochemical properties of synbiotic chewing gum: study with univariate and multivariate analyses

Nowadays, there is an increasing tendency toward using probiotics in different food systems. In this work, probiotic survival, texture features and sensory properties of synbiotic chewing gum containing encapsulated probiotic organisms (Lactobacillus reuteri) were studied. Probiotics were encapsulated using alginate, inulin (0-1%) and lecithin (0-1%). Storage trials showed that, unlike control, the viability of the probiotic in encapsulated samples was retained after 21 days. Probiotic survival was increased by increasing of inulin and lecithin in cell walls. Samples containing encapsulated organisms had different texture parameters compared to the control. Sensory panelists liked the chewing gum with encapsulated lactobacilli. Thus, chewing gum has been shown to be an excellent food for delivery of probiotic lactobacilli. Principal component analysis (PCA) allowed discriminating among probiotics survival and chewing gum specialties. Partial least squares regression (PLSR) models were applied to find out the relationships between sensory and instrumental data.

The potential benefits of sugar-free chewing gum on the oral health and quality of life of older people living in the community: a randomized controlled trial

OBJECTIVES

To determine the effects of prescribing sugar-free chewing gum on the oral health and quality of life of dentate older people living in the community and attending for routine dental care.

METHODS

A randomized controlled trial was conducted on 186 older people who were not regular chewers of gum, (aged 60 years and over with ≥ 6 teeth) recruited from primary care clinics. Participants were randomly allocated to a gum-chewing group (chewing xylitol-containing gum twice a day for 15 min; n = 95) or a control group (no gum; n = 91). Both groups were examined at baseline and at the end of the study (6 months later). The primary outcome measure for the study was increased in stimulated saliva flow rate. Secondary measures included improvements in Plaque and Gingival Indices, and self-perceived change in oral health.

RESULTS

The retention rate for the study was 78.5% (n = 146 at follow-up); reported compliance with the protocol was 84% (ranged between 12% and 100%). There was no significant change in the saliva flow of the gum-chewing group (1.20-1.17 ml/min), while the control group experienced an increase in flow rate (1.06-1.32 ml/min; P = 0.001). The gum-chewing group, however, demonstrated significant improvement in Plaque and Gingival Index scores over the control group. For the Plaque Index, the mean scores (±SD) were 0.29 (±0.29) and 0.56 (±0.46) for the gum-chewing group and control groups, respectively (P < 0.001), at the second examination, which remained significant after controlling for age and saliva flow rate. For the Gingival Index, the scores were 0.73 (±0.30) and 0.92 (±0.32), respectively (P < 0.001), which persisted after controlling for age. A significantly higher proportion of participants in the gum-chewing group perceived that their oral health had improved during the study period in comparison with the control group (40% cf 21%; P = 0.016).

CONCLUSIONS

Prescription of sugar-free chewing gum to dentate older people living in the community and attending routine dental services was not associated with a significant increase in stimulated saliva flow. There were, however, significant improvements in Plaque and Gingival Index scores, and in self-perceived oral health.

Sugar-free chewing gum and dental caries: a systematic review

Objective:

To appraise existing evidence for a therapeutic / anti-cariogenic effect of sugar-free chewing gum for patients.

Method:

9 English and 2 Portuguese databases were searched using English and Portuguese keywords. Relevant articles in English, German, Portuguese and Spanish were included for review. Trials were excluded on lack of randomisation, control group, blinding and baseline data, drop out rate >33%, no statistical adjustment of baseline differences and no assessment of clinically important outcomes. Reviews were excluded on lack of information, article selection criteria, search strategy followed, search keywords, searched databases or lack of study-by-study critique tables. In cases of multiple reports from the same study, the report covering the longest period was included. Two reviewers independently reviewed and assessed the quality of accepted articles.

Results:

Thirty-nine articles were included for review. Thirty were excluded and 9 accepted. Of the 9 accepted, 2 trials of reasonable and good evidence value did not demonstrate any anti-cariogenic effect of sugar-free chewing gum. However, 7 articles, with 1 of strong, and 6 of good evidence value, demonstrated anti-cariogenic effects of chewing Sorbitol, Xylitol or Sorbitol/Xylitol gum. This effect can be ascribed to saliva stimulation through the chewing process, particularly when gum is used immediately after meals; the lack of sucrose and the inability of bacteria to metabolize polyols into acids.

Conclusion:

The evidence suggests that sugar-free chewing gum has a caries-reducing effect. Further well-designed randomised trials are needed to confirm these findings.

Prevalence of OME Is Reduced in Young Children Using Chewing Gum

OBJECTIVE

The present study investigates a possible relationship between use of chewing gum and otitis media with effusion (OME) in children. Chewing obviously activates jaw movements, increases salivary flow, and, by the way, the rate of swallowing and the rate of activations of peritubal muscles and tubal openings. Chewing also requires nasal respiration, thus preventing mouth breathing.

DESIGN

Cross-sectional study: 1756 children (2 to 6 yr of age), apparently in good health and visiting different Dutch child health centers in the region of Utrecht were examined between September 1999 and April 2002. OME was diagnosed by combined tympanometry and otoscopy. The criterion for OME was unilateral or bilateral type B tympanogram, according to Jerger. The parents had to fill out a questionnaire with a question pertaining to the chewing habits of their child.

RESULTS

Logistic regression points out that age and season as well as chewing gum-consuming habits significantly influence the prevalence of OME. The strongest effects are age (OME becomes less frequent with age) and season (OME occurs less when climate is more favorable), but -- ceteris paribus -- a child consuming daily or at least weekly chewing gum shows significantly less chance for OME than a child who seldom consumes or consumes no chewing gum (p = 0.023).

CONCLUSIONS

In the case of regular use of chewing gum, the probability of having OME in children is reduced by 40%. It seems plausible that children with immature oral motorics do not like chewing gum.

The use of sorbitol- and xylitol-sweetened chewing gum in caries control

BACKGROUND

The author compared the caries-inhibitory action of sorbitol- and xylitol-sweetened chewing gum and assessed the role of these products in caries prevention.

TYPES OF STUDIES REVIEWED

The author reviewed studies including randomized field trials with substantial numbers of participants and observational studies. He did not review case studies. He found studies through a MEDLINE search and by hand searching.

RESULTS

When compared with sugar-sweetened gum, sorbitol-sweetened gum had low cariogenicity [corrected] when it was chewed no more than three times per day. Xylitol-sweetened gum was noncariogenic in all of the protocols tested. Some studies claimed that xylitol-sweetened gum had an anticariogenic effect, though these claims need further study. There also is good evidence that when mothers of infants and young children chew xylitol-sweetened gum, it will block transmission of mutans streptococci from mother to child.

CLINICAL IMPLICATIONS

The evidence is strong enough to support the regular use of xylitol-sweetened gum as a way to prevent caries, and it can be promoted as a public-health preventive measure. Chewing xylitol-sweetened gum, especially for patients who like chewing gum, can be fitted readily into a regimen that includes frequent fluoride exposure, good oral hygiene and regular dental appointments.

Functional tubal therapy for persistent otitis media with effusion in children: myth or evidence?

Otitis media with effusion (OME), a form of inflammatory middle ear disease, is a common reason for young children to visit their family doctor and to have surgery. Tubal dysfunction plays a major role in the pathogenesis. In case of persistent OME, there seems to be a logical rationale for a favourable effect on the tubal dysfunction of a functional active motoric approach combined with behavioral changes (hygiene), and as a consequence for a therapeutic effect on the middle ear disease. The basic principles of this functional treatment are: active ventilation of the middle ear, correction of immature and undesirable deviant mouth habits, increasing swallowing frequency, activating jaw and palate movements, and encouraging the use of chewing gum. The bases for this functional therapy are critically analysed, and it may be concluded that all of these principles rely upon evidence based physiological mechanisms. However, the limited available clinical data from the literature are reviewed, and appear as methodologically weak. The results of an own prospective randomized pilot study comparing functional treatment with watchful waiting may be considered encouraging, since a borderline significance level was reached with a small amount of subjects.

The efficacy of a fluoride chewing gum on salivary fluoride concentration and plaque pH in children

OBJECTIVES

The purpose of this study was therefore to study the influence of different chewing times on the salivary F concentration and on the recovery of plaque pH directly after a sucrose rinse on both the chewing and the non-chewing side.

METHODS

For this purpose, one piece of sugar free chewing gum was chewed to 10 healthy subjects (aged 8-10 years, 5 male and 5 female children). Subjects refrained from toothbrushing for 3 days. On the fourth day, they rinsed for 1 min with 10 microl of a 10% sucrose solutions. After 8 min, chewing gum was given and started to chew for either 5, 10, 20, 30, 45 min or control (sucrose rinse). Thus, altogether six test sessions were repeated at one week intervals. Measurements of F concentration in saliva and pH of approximal plaque were carried out at two contralateral sites for up to 60 min.

RESULTS

Higher salivary F concentrations were found on the chewing side than on the non-chewing side (expressed as) (p<0.05). But, the difference between the chewing and the non-chewing side was not obvious for the plaque pH (expressed as AUC) (p>0.05). Therefore, this study showed that: (1) the F concentrations in saliva after chewing a F containing chewing gum had only small numerical differences among the various chewing times, with the exception for 5 min. All chewing time periods showed statistically significant differences between chewing and non-chewing side. (2) The prolonged chewing time increased the plaque pH recovery after a sucrose rinse (p<0.05) but there was no statistically significant difference on both of the chewing and non-chewing side (p>0.05).

CONCLUSION

The results of this study indicated that a prolonged chewing time was favorable to the plaque pH recovery after a sucrose rinse and, to a certain extent, to the salivary fluoride concentration. Also it was shown that the F concentration in saliva was strongly dependent on which side the subject chewed on.

The oral environment: the challenge for antimicrobials in oral care products

For any antibacterial/ anti-plaque system from an oral care product to be effective, it must firstly be delivered and retained at relevant sites in the oral cavity and secondly, remain active within the chosen formulation to successfully target the biofilm cells within dental plaque. This must include inhibition of the growth and metabolism of relevant organisms associated with disease. This review will concentrate on understanding the environmental conditions in which such oral care products must work and summarise the activity within the oral cavity of the main antibacterial and anti-plaque agents in common oral care products, namely chlorhexidine, essential oils, metal salts and Triclosan. Routes to further enhance the activity of these products, together with the use of relatively novel formats such as confectionery products to provide added consumer oral health benefits will be considered.

Salivary flow rate and pH during prolonged gum chewing in humans

Gum chewing for 20 min causes an increase in salivary flow rate and salivary pH. Most people chew gum for longer than 20 min, and our aim was to determine how whole mouth salivary flow rate and pH might adapt during prolonged gum chewing. Resting saliva was collected over 5 min; gum-stimulated saliva was collected at intervals during 90 min, chewing a single pellet (1.5 g) of mint-flavoured, sugar-free gum (n = 19). Subjects chewed at their own preferred rate and style. Both salivary flow rate and pH were increased above resting levels for the entire 90 min. The salivary flow was significantly greater (anovaP < 0.05) than resting flows up to 55-min chewing. The saliva pH remained significantly higher (P < 0.0001) than the resting pH even after 90-min chewing. When the experiment was repeated with the gum pellets replaced at 30 and 60 min (n = 9), similar increases in salivary flow rate and pH were found. In the latter experiment, there was no evidence of any cumulative effects on flow or pH. The persistent increase in salivary pH in particular could be beneficial to oral and dental health.

The efficacy of two prototype chewing gums for the removal of extrinsic tooth stain

AIM

To compare the potential efficacy of two prototype chewing gums in extrinsic stain removal on natural teeth.

SETTING

Dental school clinics.

DESIGN

Double-blind, two groups, parallel design.

PARTICIPANTS

76 adult volunteers (32m, 44f, mean age: 20.6 years old).

METHODS

Oral hard and soft tissue health was examined. The subjects were randomly assigned to use either Product A (without active ingredients) or Product B (with active ingredients). Each subject was asked to brush their teeth for one minute twice daily (mornings and nights) and chew the gums supplied for 15 min (2 dragees each time), three times daily, once after each meal (breakfast, lunch and dinner) for the entire four-week duration. Dental stain assessment was made on the 12 incisors using the Lobene Stain Index (LSI).

RESULTS

The overall difference between the stain scores after 4-weeks' use of the chewing gums was statistically significant (p<0.01) for both test Product A (10.84) and Product B (7.77) with regard to the mean baseline stain scores (21.57). This difference represented a 48% reduction in stain scores for those subjects using Product A, while the reduction was 64% for the subjects using Product B.

CONCLUSIONS

The results of this in vivo study suggest that chewing gums with and without active ingredients have potential effect on stain removal after regular use for one month.

Sorbitol compared with xylitol in prevention of dental caries

OBJECTIVE

To summarize published data on the comparative efficacy of sorbitol and xylitol for prevention of dental caries.

DATA SOURCES

Published double-blind comparative trials, using sorbitol and xylitol products, identified by MEDLINE (January 1966-December 1998) and International Pharmaceutical Abstracts (January 1970-December 1998) searches.

DATA SYNTHESIS

Clinical trials generally used sorbitol and xylitol gums, which patients chewed three to five times daily for 20-40 months. Xylitol was superior to sorbitol in two longer, secondary dentition trials (30-63% reductions), but not in two primary dentition trials.

CONCLUSIONS

The data suggest that xylitol-containing gums may provide superior efficacy in reducing caries rates in high-risk populations.

In situ de- and remineralisation of enamel in response to sucrose chewing gum with fluoride or non-fluoride dentifrices

OBJECTIVES

Enhancement of the remineralisation of artificial enamel lesions has been observed in an intraoral model whether subjects chewed gum sweetened with a non-cariogenic sweetener such as sorbitol [1-3] or sucrose [4] after meals or snacks, and with use of a conventional (1500 ppm F) fluoride dentifrice. Since most of the clinical surveys which have shown the potential cariogenicity of sucrose chewing gum [5] were conducted before use of fluoridated dentifrices became widespread, the effect of fluoride dentifrice on de- and remineralisation of artificial lesions in enamel in response to chewing sucrose-sweetened gum has been examined with the aim of attempting to resolve this apparent discrepancy.

METHODS

Subjects wore an intraoral device bearing an enamel lesion and chewed one piece of sucrose gum for 20 min after each of three meals and two snacks daily for two 3-week periods, during which they used a dentifrice containing either 0 or 1500 ppm F in a double-blind, cross-over design. Measurement of the mineral content of the lesions was determined by microradiography or polarised light microscopy.

RESULTS

It was found that remineralisation tended to occur with 1500 ppm F dentifrice, but demineralisation with non-F dentifrice; the difference in enamel mineral content between the two periods was significant (P < 0.05).

CONCLUSIONS

The results indicate that the potential cariogenicity of sucrose-containing chewing gum may indeed be negated by the use of a conventional fluoride dentifrice.

The effect of chewing sugar-free gum after meals on clinical caries incidence

To determine the effect of chewing sugar-free gum on caries incidence, the authors conducted a randomized clinical study. A total of 1,402 children in Puerto Rico, in grades 5 through 7 at baseline, completed the study. They were randomized by classroom into a control group or chewing gum group; those in the gum group were instructed to chew sugar-free gum for 20 minutes after each of three meals a day. Clinical and radiographic evaluations were performed at baseline and after two and three years. The results show that all subjects and high-risk subjects, respectively, in the gum group developed 7.9 percent and 11.0 percent fewer decayed, missing or filled surfaces than subjects in the control group. Based on these findings, the authors concluded that chewing sorbitol-based sugar-free gum after eating significantly reduces the incidence of dental caries.

Caries prevention in the 21st century

While the incidence of caries has decreased during the past 50 years because of the introduction of water fluoridation and fluoride toothpastes, it is still widespread. Improved therapies, using topical treatments to replace lost calcium and phosphate minerals from early carious lesions, will reduce the need for surgical intervention in the future. Early caries detection techniques currently being developed will allow dentists to maximize the usefulness of these treatments.

Effect of three months' frequent use of sugar-free chewing gum with and without urea on calculus formation

Studies on the relationship between gum-chewing and calculus formation have produced contradictory results, and it is not clear whether frequent use of chewing gum promotes or inhibits calculus formation. Also, little is known about whether the addition of a small amount of urea to the chewing gum influences calculus formation. The aim of this investigation was to study the effect of sugar-free chewing gum--with and without urea--on calculus formation and some associated clinical variables. Three three-month periods were studied in a double-blind, crossover design, during which the subjects: (1) chewed 5 pieces/day of a sugar-free, urea-containing chewing gum (20 mg urea/piece); (2) chewed 5 pieces/day of a sugar-free, non-urea-containing gum; or (3) performed no gum-chewing. Twenty-nine persons, all calculus-formers, participated. They were scored for calculus at mesio-lingual, lingual, and disto-lingual sites on the 6 anterior mandibular teeth according to the Volpe-Manhold index. Plaque and gingival bleeding index, stimulated salivary secretion rate and buffer capacity, resting plaque pH, mutans streptococci in saliva and plaque, and lactobacilli in saliva were also determined. No differences in calculus formation were found among the 3 periods. The resting plaque pH was higher after the period with urea-containing gum than after the period with non-urea-containing gum and the no-gum period (p < 0.05). A slight increase in stimulated salivary secretion rate was found after the 2 gum periods (p < 0.05). The plaque and gingival bleeding indices decreased, while resting plaque pH and salivary buffer capacity increased throughout the entire study (p < 0.05). No significant differences in prevalence of the acidogenic micro-organisms were found among the test periods. The main conclusion from this study is that three months' frequent use of sugar-free chewing gum--with or without urea--neither promotes nor inhibits calculus formation.

Relation between saliva flow and flavor release from chewing gum

The objective of this study was to investigate whether or not parotid saliva flow is a significant determinant of flavor release from chewing gum. Cherry-flavored gum with 3 concentrations of citric acid (0.5, 1, and 2%) acting as a sialagogue was evaluated for sweetness and cherry flavor in duplicate by 13 subjects, using a computerized system for simultaneous time-intensity (TI) measurements and unilateral collection of parotid saliva. With increased acidity in the gum, maximum intensity of, and area under, the cherry flavor curve increased (p < 0.001), whereas total duration of sweetness decreased (p < 0.05). Large interindividual differences were found for parotid saliva flow in response to chewing gum. Mean unilateral parotid saliva flows in response to stimulation with water and gum with 0.5, 1, and 2% citric acid were 0.07, 0.30, 0.36, and 0.44 g/min, respectively. There was a significant positive correlation between saliva flow and time to reach maximum intensity of sweetness (p < 0.05) and of cherry flavor (p < 0.01), with "high-flow" subjects taking longer to reach maximum intensity than "low-flow" subjects for both attributes. We conclude that parotid saliva flow may affect the rate of flavor release, but not how much nor for how long flavor is released.

The use of low-tack chewing gum for individuals wearing orthodontic appliances

A clinical study was carried out to determine the acceptability of a sugar-free, low-tack chewing gum by orthodontic patients undergoing fixed appliance treatment. Twenty-five orthodontic and 25 non-orthodontic control subjects were questioned on their preference between regular-tack and low-tack chewing gum. The orthodontic subjects showed a strong preference for the low-tack gum compared with the regular-tack gum. It was concluded that low-tack, sugar-free chewing gum can be used by orthodontic patients to increase saliva flow, with the potential to promote remineralization and help reduce white spot lesion formation related to fixed orthodontic appliances. This gum should also be of value in patients being treated for xerostomia who are wearing a partial denture.

Gum chewing and jaw muscle fatigue and pains

To study possible associations between gum chewing and fatigue and pains in the jaw muscles, eight healthy adults performed prolonged idling, prolonged unilateral chewing of gum, and brief vigorous clenching of the teeth (MVC). Through surface electromyography (EMG), the authors monitored the cumulative (microV.s) as well as the average rates (microV.s-1) of contractile activities in the right and left masseter muscles. During 10 min of idling there was an absence of muscle fatigue and muscle pains when the EMG rates of the right and left masseter muscles were 2% and 3%, respectively, of those required to elicit isometric muscle pains through MVC. During 10 min of right-sided gum chewing at a rate of 1.2 Hz, the majority of subjects (75%) experienced weak jaw muscle fatigue-not jaw muscle pains-when the EMG rates of the right and left masseter muscles were 38% and 19%, respectively, of those required to elicit isometric pains through MVC. In comparison with 10 min of idling, the weak muscle fatigue of 10 min of unilateral gum chewing appeared when the total contractile activities of the right and left masseter muscles were increased by 1664% and 519%, respectively. It seemed as if prolonged unilateral gum chewing and previous pain-releasing MVC caused some sensitization of muscle nociceptors which, in turn, aggravated subsequent isometric jaw muscle pains elicited through MVC. Even though the right masseter muscle was the most frequent site of clinical fatigue and pains, the authors found no evidence supporting the theoretical foundation of the myofascial pain/dysfunction syndrome.

The site-specificity of supragingival calculus deposition on the lingual surfaces of the six permanent lower anterior teeth in humans and the effects of age, sex, gum-chewing habits, and the time since the last prophylaxis on calculus scores

The hypotheses to be tested were: (i) that chewing sugar-free gum frequently and for long periods would be associated with higher amounts of supragingival calculus, and (ii) that there would be no site-specificity of calculus deposition on the lingual surfaces of the 6 lower anterior teeth. Subjects, 436 in Glasgow and 191 in Winnipeg, were scored for calculus at mesial, lingual, and distal sites on the lingual surface of each of the 6 lower anterior teeth, by the Volpe-Manhold method. They also answered questions on the time since the last prophylaxis, the frequency of gum chewing, the type of gum chewed, and the length of a typical gum-chewing episode. A subset (233) of the Glasgow subjects were scaled and re-scored for calculus 3 months later. When the data for the logarithmic transformations of the initial calculus scores were subjected to stepwise multiple-regression analysis, the only factor which correlated significantly with initial calculus scores in both cities was the time since the last prophylaxis. In the Glasgow subjects scored 3 months after a prophylaxis, there was a negative correlation between chewing sugar-free gum and calculus scores, whereas in the Winnipeg subjects, age and the chewing of sucrose-containing and sugar-free gum were positively correlated with calculus scores. Thus, the results were contradictory with respect to the first-tested hypothesis. The calculus distribution patterns were very similar in the subset of Glasgow subjects and the Winnipeg subjects, with the amounts on the lateral incisors and canines averaging 70.2% and 44.5%, respectively, of those on the central incisors. Thus, the second hypothesis was disproved.

Computer modeling of the effects of chewing sugar-free and sucrose-containing gums on the pH changes in dental plaque associated with a cariogenic challenge at different intra-oral sites

Variation in salivary access to different intra-oral sites is an important factor in the site-dependence of dental caries. This study explored, theoretically, how access is modified by chewing sugar-free and sugar-containing gums. A finite difference computer model, described elsewhere, was used. This allowed for diffusion and/or reaction of substrate, acid product, salivary buffers, and fixed-acid groups. Site-dependent saliva/plaque exchange was modeled in terms of a 100-microns-thick salivary film covering the plaque (a) flowing directly from the salivary ducts, (b) flowing from the intra-oral salivary pool, or (c) exchanging with the pool. Computed flow-velocities or rates of exchange were based on previous intra-oral measurements. The model was also tested against an in vitro study conducted by two of the authors. In addition, the three proposed models of saliva/plaque interaction were compared, and the effect of salivary film thickness investigate. Results suggested that: (1) although sugar-free gum chewed during a cariogenic challenge causes a rapid rise in plaque pH, sucrose-containing gums cause the pH, after a temporary rise resulting from increased salivary flow, to stay low for an extended period; (2) the computer model reproduced in vitro tests reasonably well; (3) although the three models of the plaque/saliva interaction start from different assumptions, two lead to closely related predictions; and (4) increasing the assumed salivary film thickness by a large amount (e.g., from 50 to 200 microns) caused no change in modeled Stephan curves, as long as these changes were accompanied by appropriate reductions in film velocity, in accord, theoretically, with the practical clearance data.

The effects of chewing frequency and duration of gum chewing on salivary flow rate and sucrose concentration

On ten separate occasions, unstimulated saliva was collected from 12 adults and then eight samples of saliva over a 20-min period while chewing, in random order, 3 g of either Wrigley's Spearmint chewing-gum or gum-base at frequencies of 35, 50, 70, 90, or 130 chews/min. With both stimuli, flow rates peaked in the first minute of stimulation and then fell with time. A repeated-measures analysis of variance showed that for both the gum and the gum-base, flow rates were independent of chewing frequency, except during the first minute with the chewing-gum. The gum elicited a significantly higher flow rate over the first 4 min of chewing, while the base elicited a significantly higher flow rate over the 8-20-min period of chewing. The sucrose concentration in saliva was also independent of chewing frequency. The salivary sucrose concentration peaked during the second minute of chewing (mean +/- SE = 424.7 +/- 20.0 mM) and the concentration then fell progressively with time. However, sucrose was still being released into saliva during the 15-20 min period of chewing (12.6 +/- 0.8 mM). Gum-base which had been chewed without access to saliva was softer than unchewed base but showed no change in filler content or a reduction in the average molecular weight. The decrease in hardness of the chewed gum-base may have resulted from improved mixing of heterogeneous phases and increased dispersion of plasticizing agents.

Food components and caries

For many decades, sugars have been the dietary constituents receiving the most attention in relation to their effects on dental caries. Frequently, however, there is little relationship between the amount of sugar in a food and its ability to induce caries. Therefore, it is clear that constituents in the diet can influence the ability of plaque to lower the pH of sugar solutions. For instance, replacing sugar in foods with xylitol, sorbitol, saccharin, or aspartame may lead to a reduction in the incidence of dental caries. All these sugar substitutes are non-cariogenic, and some may possess cariostatic properties. The presence of arginine-rich proteins in the diet may provide a ready source of this amino acid, which is the substrate for the arginine deiminase pathway which can result in a rapid elevation of plaque pH values. Proline can act as an acceptor for protons from lactate in the Stickland reaction. This is a major but much-neglected metabolic pathway in dental plaque. The presence of fat in experimental diets has been shown to affect their cariogenicity. The effects have been ascribed to enhanced clearance of sugars from the mouth. It is also conceivable that several fatty acids express a potent antibacterial effect. The presence of calcium and phosphorus has been shown to influence the cariogenicity of foods; the effect, however, is restricted to the food containing the minerals. Evidence suggests that pyridoxine (vitamin B6) may exert a cariostatic effect by enhancing decarboxylation activity in dental plaque. It is clear that sugar alone is not the sole determinant of whether food is cariogenic. Furthermore, myriad substances may hinder or enhance the caries-promoting properties of sugars in the diet.

Saliva stimulation and caries prevention

The protective role of saliva is demonstrated by the rampant caries seen in human subjects with marked salivary hypofunction, and in desalivated animals. In normal cases, however, the relationship between saliva flow and coronal or root caries experience is doubtful, and to examine the concept that stimulation of saliva might have protective effects against caries, one must look beyond a simple correlation between caries and flow rate. Protective properties of saliva which increase on stimulation include salivary clearance, buffering power, and degree of saturation with respect to tooth mineral. These benefits are maximized when saliva is stimulated after the consumption of fermentable carbohydrates, by reducing the fall in plaque pH leading to demineralization and by increasing the potential for remineralization. Plaque acid production is neutralized, and experimental lesions in enamel are remineralized, when gum is chewed to stimulate saliva after a carbohydrate intake. The pH-raising effects are more easily explained by the buffering action of the stimulated saliva than by clearance of carbohydrates. The remineralization action depends upon the presence of fluoride. These findings suggest that the protective actions of saliva can be mobilized by appropriate salivary stimulation, and that in addition to established procedures such as tooth cleaning and fluoride regimens, eating patterns which lead to saliva stimulation to increase the potential for saliva protection might be included in recommendations for caries prevention. Confirmation of this concept in clinical tests is required.

Diet patterns and caries

Few dietary studies have been designed to investigate the effects of intake patterns of food items upon the environment of the teeth. This brief review considers evidence about the effects of choice, combination, and sequence of ingested food and drink upon the pH of human dental plaque in vivo. A series of three studies, which were designed to investigate some of the intra-oral biological events associated with cariogenicity during various eating patterns, are discussed. The principal findings show that if a "meal" includes an item which contains carbohydrate such as sucrose, glucose, or fructose which is rapidly fermented by the acidogenic microorganisms in dental plaque, there will be rapid acid production and the plaque pH will fall. However, other items eaten immediately before, during, or after the consumption of the sugary item can influence the plaque pH. If the non-sugary item stimulates saliva, it will have a pH-raising effect. The remineralizing potential may be enhanced if, for instance, calcium or fluoride is released from the food. However, if one sugary item is followed by another, the demineralizing potential may be enhanced. The results of these experiments are discussed in the context of our current understanding of the dynamics of the carious process. Recent preliminary experiments suggest that other factors, such as the individual subject's speed of consumption, may also affect the cariogenic potential of the oral environment.

Cariologic aspects of xylitol and its use in chewing gum: a review

Several studies indicate that xylitol is not metabolized to acids either in pure cultures of oral microorganisms in vitro or in dental plaque in vivo. Chronic consumption of xylitol-sweetened chewing gum resulted in reduction of dental plaque, suppression of mutans streptococci, and reduced adhesiveness of plaque. So far, four field studies with regimens including chewing gum and other xylitol-containing products and four clinical trials have been carried out. All of the latter studies showed that a daily intake of two to three pieces of xylitol gum resulted in a defined reduction of caries. There are indications that regular and prolonged use of xylitol chewing gum may have a caries-preventive effect.

Effects on whole saliva of chewing gums containing calcium phosphates

To evaluate chewing gums as a vehicle to increase salivary mineral saturation levels and enhance salivation, monocalcium phosphate monohydrate (MCPM) and an equimolar mixture of tetracalcium phosphate (TTCP) with dicalcium phosphate anhydrous (DCPA) were chosen as experimental chewing gum additives. Each of eight subjects chewed a commercial sugarless bubble gum (control) for 16 min or the same gum to which 5 wt% of MCPM or the TTCP-DCPM mixture had been added. The saliva samples collected every 2 min were analyzed for weight, pH, and total calcium (Ca) and phosphate (P) concentrations. Both experimental gums were found to increase significantly the Ca and P concentrations of saliva during the 16-minute period even more than with a previously evaluated gum that contained dicalcium phosphate dihydrate. The degree of saturation of tooth mineral was significantly increased by both experimental gums, with the greater increase being produced by the TTCP-DCPA gum. The MCPM gum produced a significantly greater saliva flow and a lower salivary pH than did the control and TTCP-DCPA gums. The results suggest that the experimental gums may be useful for promoting remineralization in general and for inducing salivation in xerostomic patients.

An in vitro stimulation of the effects of chewing sugar-free and sugar-containing chewing gums on pH changes in dental plaque

The objective of these studies was to simulate the effect of chewing sugar-free and sucrose-containing chewing gums on the return of the pH to neutrality after exposure to sucrose of plaque located on the buccal (BLM) and lingual (LLM) surfaces of the lower molar teeth. In study 1, a 0.5-mm-deep artificial plaque containing Streptococcus oralis cells was exposed to 10% sucrose for one min, and a 0.1-mm-thick film of sucrose-free artificial saliva was then flowed over the plaque surface at the unstimulated salivary film velocities previously found at the BLM and LLM sites. At the time of the pH minimum (pH 4-5), one of three conditions was simulated: (a) a no-gum-chewing control, or chewing for 20 min on either (b) a sugar-free gum or (c) a sucrose-containing gum. The recovery of the plaque pH to resting values was rapid during simulation of chewing a sugar-free gum (SFG), much slower with the no-gum control, and even slower with simulation of chewing a sucrose-containing gum (SCG). The pH recovery was slower with the BLM than the LLM plaque. In study 2, the BLM plaque was exposed to a 2% sucrose solution for 20 min under stimulated salivary conditions, to simulate the consumption of a meal, followed by one of conditions (a), (b), or (c) described above. The pH recovery with simulation of chewing a SCG was faster than with the no-gum control, but much slower than with the SFG simulation.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of chewing-gum stick size and duration of chewing on salivary flow rate and sucrose and bicarbonate concentrations

The objectives were to determine (1) the relations between salivary flow rate and the sample weights of chewing-gum and gum base, (2) whether any reduction in salivary flow rate with duration of chewing is due to a reduction in hardness of gum base with chewing, and (3) the sucrose and bicarbonate concentrations in saliva elicited by different weights of chewing-gum containing sucrose. Ten subjects chewed, for 20 min, samples of 1, 2, 3, 6 and 9 g of gum base and of a sucrose-containing chewing-gum. With each sample, salivary flow rates peaked initially and then fell to a relatively constant value. Flow rates during the periods of 1-2 and 15-20 min were linearly related to the logarithm of sample weight. With the chewing-gum samples, virtually all the sucrose was released into the saliva during the 20 min of chewing, with peak concentrations (201-666 mM) at 1-2 min, and bicarbonate concentrations were higher with the 9-g than the 3-g samples. Six subjects chewed 3 g of gum base and within 45 min the weight of base had increased to 122% of the original, presumably due to the uptake of saliva. The hardness of gum base was determined at 21 and 36 degrees C, 21 and 36 degrees C after it had been chewed, and 21 degrees C after it had been chewed without exposure to saliva, and gave Brinell values of 0.277, 0.038, 0.022, 0.002 and 0.061, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of chewing gum use on in situ enamel lesion remineralization

Two independent cross-over studies investigated the possibility of enhanced early enamel lesion remineralization with the use of chewing gum. The first study involved a sorbitol-containing chewing gum, and the second, which had an identical protocol, tested a sucrose-containing chewing gum. In each study, 12 volunteers wore in situ appliances on which were mounted enamel sections containing artificial caries lesions. Subjects brushed twice daily for two min with a 1100-ppm-F (NaF) dentifrice (control and test) and in the test phase chewed five sticks of gum per day for 20 min after meals and snacks. Microradiographs of the enamel lesions were made at baseline and at the end of the seven-week experimental period. In the sugar-free gum study, the weighted mean total mineral loss (delta z) difference [(wk7-wk0) x (-1)] was 788 vol.% min. x micron for the gum, corresponding to remineralization of 18.2%, vs. the control value of 526 vol.% min. x micron, 12.1% remineralization (p = 0.07). There were no significant differences for the surface-zone (p = 0.20) and lesion-body (p = 0.28) values. In the sucrose-containing gum study, the delta z difference was 743 vol.% min. x micron for the gum, corresponding to a remineralization of 18.3%, vs. the control value of 438 vol.% min. x micron, 10.8% remineralization (p = 0.08). The surface-zone values were not significantly different (p = 0.55). For the lesion body, however, the sucrose-containing gum value of 6.11 vol.% min. was significantly different (p = 0.01) from that of the control (2.81 vol.% min.).

Intra-oral models to assess cariogenicity: evaluation of oral fluoride and pH

The main purpose of this paper is to review the various methods used for evaluation of fluoride retention in saliva, plaque, and enamel following application of topical anti-caries treatments such as F dentifrices and F mouthwashes. Such methods monitor delivery of fluoride to the site of action, the mouth, and so can be regarded as assessing potential for treatment action. It is concluded that intra-oral fluoride measurements are appropriate to support bioequivalence claims for anti-caries treatments, provided that particular chosen methods have been calibrated against clinical data. Studies purporting to show superiority are of interest mechanistically, but links to caries are not sufficiently understood to define superiority claims. A wide variety of methods has been used for determination of the fluoride content of enamel. Of these, well-established methods such as the micro-drill and acid-etch procedures are appropriate for routine comparative testing, whereas sophisticated instrumental techniques such as SIMS are more appropriate for detailed mechanistic studies. Intra-oral pH measurements are also relevant to many topical treatments. Single-site determinations in plaque are preferred, but for comparative studies non-specific determinations may be adequate.

Teeth for the future

The main dietary influences on teeth are, with the exception of ingested fluoride, local rather than systemic. The frequent use of carbohydrates which can be rapidly fermented by dental plaque micro-organisms is the major factor in dental decay. Sweetened and/or highly acidic soft drinks or medicines sweetened with sugars may damage the teeth. Similarly infant's comforters also have their dangers if they provide prolonged exposure of the teeth to cariogenic conditions. Although dental caries is primarily a disease of children many adults still develop new lesions and adults who have lost gingival tissue through periodontal disease may develop root surface caries. Pathological conditions of the oral mucosa can arise from nutritional disorders or inappropriate dietary habits. Health education is most effective when it carries a positive message so encouraging patients to eat the right kind of tasty snacks and to round off meals with sugar-free products or a modicum of cheese should in healthier eating without conflicting with general health guidelines.