The effect of gum chewing on xerostomia and salivary flow rate in elderly and medically compromised subjects: a systematic review and meta-analysis.

BACKGROUND: Xerostomia negatively affects quality of life. Symptoms include oral dryness; thirst; difficulty speaking, chewing, and swallowing food; oral discomfort; mouth soft tissue soreness and infections; and rampant tooth decay. The objective of this systematic review and meta-analysis was to investigate if gum chewing is an intervention that results in objective improvements in salivary flow rates and subjective relief from xerostomia. METHOD: We searched electronic databases including Medline, Scopus, Web of Science, Embase, Cochrane Library (CDSR and Central), Google Scholar and the citations of review papers (last searched 31/03/23). The study populations included: 1) elderly people with xerostomia (> 60 years old, any gender, and severity of xerostomia), and 2) medically compromised people with xerostomia. The intervention of interest was gum chewing. Comparisons included gum chewing vs. no gum chewing. The outcomes included salivary flow rate, self-reported xerostomia, and thirst. All settings and study designs were included. We conducted a meta-analysis on studies where measurements of unstimulated whole salivary flow rate for both a gum chewing, and no gum chewing intervention (daily chewing of gum for two weeks or longer) were reported. We assessed risk of bias using Cochrane's RoB 2 and ROBINS-I tools. RESULTS: Nine thousand six hundred and two studies were screened and 0.26% (n = 25) met the inclusion criteria for the systematic review. Two of the 25 papers had a high overall risk of bias. Of the 25 papers selected for the systematic review, six met the criteria to be included in the meta-analysis which confirmed a significant overall effect of gum on saliva flow outcomes compared to control (SMD = 0.44, 95% CI: 0.22-0.66; p = 0.00008; I2 = 46.53%). CONCLUSIONS: Chewing gum can increase unstimulated salivary flow rate in elderly and medically compromised people with xerostomia. Increasing the number of days over which gum is chewed increases the improvement in the rate of salivation. Gum chewing is linked with improvements in self-reported levels of xerostomia (although it is noted that no significant effects were detected in five of the studies reviewed). Future studies should eliminate sources of bias, standardise methods to measure salivary flow rate, and use a common instrument to measure subjective relief from xerostomia. STUDY REGISTRATION: PROSPERO CRD42021254485.

Self-perceived mouthfeel and physico-chemical surface effects after chewing gums containing sorbitol and Magnolia bark extract.

The European Food Safety Authority recognizes the contribution of sugar-free chewing gum to oral health through increased salivation, clearance of food debris, and neutralization of biofilm pH. Magnolia bark extract is a gum additive shown to reduce the prevalence of bad-breath bacteria but its effects on self-perceived mouthfeel are unknown. This paper aims to relate the effects of sorbitol-containing chewing gum, with and without Magnolia bark extract, on tooth-surface hydrophobicity and salivary-film composition with self-perceived mouthfeel. In a crossover clinical trial, volunteers chewed sorbitol-containing gum, with or without Magnolia bark extract added, three times daily during a 4-wk time period. A subset of volunteers also chewed Parafilm as a mastication control. Oral moistness and tooth smoothness were assessed using questionnaires, and intra-oral water-contact angles were measured before, immediately after, and 60 min after, chewing. Simultaneously, saliva samples were collected, placed on glass slides, and the compositions of the adsorbed film were measured using X-ray photoelectron spectroscopy. Chewing of gum, regardless of whether or not it contained Magnolia bark extract, improved self-perceived mouthfeel up to 60 min, concurrent with a more hydrophilic tooth surface and an increased amount of O1s electrons bound at 532.6 eV in salivary films. Chewing of Parafilm affected neither tooth-surface hydrophobicity nor salivary-film composition. Accordingly, adsorption of sorbitol, rather than the presence of Magnolia bark extract or increased salivation, is responsible for improved self-perceived mouthfeel.

Potential benefits of chewing gum for the delivery of oral therapeutics and its possible role in oral healthcare.

INTRODUCTION: Over the years, chewing gum has developed from a candy towards an oral health-promoting nutraceutical. This review summarizes evidence for the oral health benefits of chewing gum, emphasizing identification of active ingredients in gum that facilitate prevention and removal of oral biofilm. AREAS COVERED: Chewing of sugar-free gum yields oral health benefits that include clearance of food debris, reduction in oral dryness, increase of biofilm pH and remineralization of enamel. These basic effects of chewing gum are attributed to increased mastication and salivation. Active ingredients incorporated in chewing gums aim to expand these effects to inhibition of extrinsic tooth stain and calculus formation, enhanced enamel remineralization, reduction of the numbers of bacteria in saliva and amount of oral biofilm, neutralization of biofilm pH, and reduction of volatile sulfur compounds. EXPERT OPINION: Evidence for oral-health benefits of chewing gum additives is hard to obtain due to their relatively low concentrations and rapid wash-out. Clinical effects of gum additives are overshadowed by effects of increased mastication and salivation due to the chewing of gum and require daily chewing of gum for prolonged periods of time. Future studies on active ingredients should focus on specifically targeting pathogenic bacteria, whilst leaving the healthy microbiome unaffected.

Extracellular Glycoside Hydrolase Activities in the Human Oral Cavity.

Carbohydrate availability shifts when bacteria attach to a surface and form biofilm. When salivary planktonic bacteria form an oral biofilm, a variety of polysaccharides and glycoproteins are the primary carbon sources; however, simple sugar availabilities are limited due to low diffusion from saliva to biofilm. We hypothesized that bacterial glycoside hydrolase (GH) activities would be higher in a biofilm than in saliva in order to maintain metabolism in a low-sugar, high-glycoprotein environment. Salivary bacteria from 13 healthy individuals were used to grow in vitro biofilm using two separate media, one with sucrose and the other limiting carbon sources to a complex carbohydrate. All six GHs measured were higher in vitro when grown in the medium with complex carbohydrate as the sole carbon source. We then collected saliva and overnight dental plaque samples from the same individuals and measured ex vivo activities for the same six enzymes to determine how oral microbial utilization of glycoconjugates shifts between the planktonic phase in saliva and the biofilm phase in overnight dental plaque. Overall higher GH activities were observed in plaque samples, in agreement with in vitro observation. A similar pattern was observed in GH activity profiles between in vitro and ex vivo data. 16S rRNA gene analysis showed that plaque samples had a higher abundance of microorganisms with larger number of GH gene sequences. These results suggest differences in sugar catabolism between the oral bacteria located in the biofilm and those in saliva.

Allyl isothiocyanate from mustard seed is effective in reducing the levels of volatile sulfur compounds responsible for intrinsic oral malodor.

Oral malodor is a major social and psychological issue that affects general populations. Volatile sulfur compounds (VSCs), particularly hydrogen sulfide (H2S) and methyl mercaptan (CH3SH), are responsible for most oral malodor. The objectives for this study were to determine whether allyl isothiocyanate (AITC) at an organoleptically acceptable level can eliminate VSCs containing a free thiol moiety and further to elucidate the mechanism of action and reaction kinetics. The study revealed that gas chromatograph with a sulfur detector demonstrated a good linearity, high accuracy and sensitivity on analysis of VSCs. Zinc salts eliminate the headspace level of H2S but not CH3SH. AITC eliminates both H2S and CH3SH via a nucleophilic addition reaction. In addition, a chemical structure-activity relationship study revealed that the presence of unsaturated group on the side chain of the isothiocyanate accelerates the elimination of VSCs.

Chewing gum containing allyl isothiocyanate from mustard seed extract is effective in reducing volatile sulfur compounds responsible for oral malodor.

PURPOSE: To evaluate the in vivo effect of chewing gum containing allyl isothiocyanate alone, and in combination with zinc salts on reduction of the level of volatile sulfur compounds responsible for oral malodor. METHODS: 15 healthy volunteers between the ages of 20-50 chewed either an experimental gum or a placebo gum for 12 minutes. Their mouth air was analyzed for volatile sulfur compounds by a gas chromatograph at baseline, immediately after chewing, and at 60, 120 and 180 minutes after treatment. RESULTS: The study revealed that allyl isothiocyanate, a constituent of mustard seed extract, can effectively reduce the concentration of volatile sulfur compounds in mouth air. Chewing gum containing 0.1% zinc lactate and 0.01% of allyl isothiocyanate eliminated 89%, 55.5%, 48% and 24% of the total VSC concentration immediately after chewing and at 1, 2, and 3 hours after chewing, respectively.

Assessment of chewing sugar-free gums for oral debris reduction: a randomized controlled crossover clinical trial.

PURPOSE: To assess the oral debris removal efficacy of two commercial sugar-free chewing gums, based on a newly developed oral debris scoring system. METHODS: A randomized, examiner-blinded, three-arm crossover study was conducted, with a 1-week washout period between the crossover phases. 42 healthy adults were randomly assigned to sugar-free stick gum (Wrigley's Extra Freshmint), sugar-free pellet gum (Wrigley's Extra Fruit) or no-gum chewing groups. Subjects consumed a single chocolate cookie, and were examined at baseline, and at 2-, 5-, and 10-minute time points with or without gum-chewing treatment. Primary outcome measures were oral debris scores on the occlusal surface, interproximal and gingival margin areas. The entire test procedure was repeated on two subsequent visits. RESULTS: The baseline conditions in the three groups did not differ significantly. Chewing either stick gum or pellet gum resulted in significantly lower oral debris scores (P < 0.0001) compared to the control (no-gum) treatment for all intraoral sites, while no significant difference was observed between the two chewing gum groups. Intra-examiner repeatability of the new scoring criteria was high throughout the study (Kappa > 0.90).

The oral health benefits of chewing gum.

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.

Health benefits of saliva: a review.

OBJECTIVE: The aim is to present a review of the literature on human saliva composition, flow rates and some of the health benefits of saliva, with emphasis on studies from our laboratory that have looked at effects of age and age-related diseases on saliva output and composition. DATA: Saliva influences oral health both through its non-specific physico-chemical properties, as well as through more specific effects. The proline-rich proteins, statherin and the histatins are salivary proteins that influence calcium phosphate chemistry, initial plaque formation and candida infection. Increases or decreases in mastication may affect saliva output. Our cross-sectional studies of saliva in a large population-based study cohort (N=1130) indicate that there is an age-related decline in saliva output for unstimulated whole, stimulated parotid, unstimulated submandibular/sublingual and stimulated submandibular/sublingual saliva, as well as some compositional alterations in anti-microbial and other proteins. Some of these alterations also appear to be specific for certain age-related medical conditions, such as diabetes mellitus. CONCLUSIONS: These studies and data presented confirm the importance of saliva in maintaining a healthy oral environment; the practitioner is encouraged to consider saliva output and medical conditions that may compromise it as part of routine dental treatment planning.