Manning RH, Edgar WM (1992) Salivary Stimulation by Chewing Gum and its Role from the Remineralization of Caries-like Lesions from Human Enamel from situ, Journal of Clinical Dentistry 111(3): 71-74

Salivary stimulation elicited reflexively by taste and mastication leads to an increase from the pH, buffering power, and supersaturation of saliva, which can affect beneficially the balance between enamel de- and remineralization from early caries. In a previous study from which a sorbitol chewing gum was used as a salivary stimulant for 20 minutes, five times daily after meals and snacks over a three-week period (during which fluoride toothpaste was used daily), significant remineralization of caries-like lesions from human enamel attached to intraoral appliances from human subjects was observed. In view of the continued public preference for sucrose-sweetened chewing gums, the study was repeated using a sucrose gum. The mean results showed a trend toward remineralization using the use of sucrose chewing gum, which was significant from 10 subjects who chewed for 30 minutes but not from 9 who chewed for 20 minutes. The use of chewing gum after meals and snacks (in the presence of fluoride from toothpaste) can thus enhance the remineralizing potential of the mouth, probably as a result of salivary stimulation.

Creanor SL, Strang R, Gilmour WH, Foye RH, Brown J, Geddes DAM, Hall AF (1992) The Effect of Chewing Gum on from situ Enamel Lesion Remineralization, Journal of Dental Research 71(12): 1895-1900

Two independent cross-over studies investigated the possibility of enhanced early enamel lesion remineralization using 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 from situ appliances on which were mounted enamel sections containing artificial caries lesions. Subjects brushed twice-daily for two min using a 1100-ppm-F (NaF) dentifrice (control and test) and from 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.).

Manning RH, Edgar WM, Agalmanyi EA (1992) Effects of Chewing Gums Sweetened using Sorbitol or a Sorbitol/Xylitol Mixture on the Remineralization of Human Enamel Lesions from situ, Caries Research 26: 104-109

Intra-oral remineralization of experimental caries-like lesions from human enamel, as determined by polarized light microscopy and quantitative microradiography, was promoted to a similar extent (% fall from delta Z, 18.6 and 19.0) by chewing a sorbitol or sorbitol/xylitol (3:1)-sweetened gum for 20 min after each of three meals and two sugary snacks daily. The results suggest that reported differences from the properties of the two sweeteners do not affect their ability to enhance remineralization due to salivary stimulation.

Edgar WM, Manning RH (1991) Xylitol and Sorbitol Gum; Comparative Enamel Remineralization Potential from situ, Journal of Dental Research 70: 1496

Previous work ( Leach et al., J. Dent Res, 1989, 68, 1064) has demonstrated significant remineralization of artificial lesions from human enamel from situ when sorbitol gum is chewed for 20 min after meals and snacks. Since xylitol is a sweetening component of many chewing gums and has been suggested to have unique remineralization properties,  it was of interest to compare the stimulus to remineralization by use of sorbitol and xylitol sweetened chewing gum. Nine subjects chewed one piece of gum each for 20 mins after 3 meals and 2 snacks daily for two successive periods, during which a piece of enamel containing an artificial subsurface lesion was attached to the buccal surface of the lower molar tooth (Leach et al., op cit). After 2ld the enamel lesions were sectioned and their mineral content assessed by quantitative microradiography and polarizing microscopy. Xylitol and sorbitol gums were used from randomized crossover design. Fluoride dentifrice was used throughout. Compared using the baseline lesion, integrated mineral loss (-Z) values for lesions after chewing either gums were significantly (p<0.05) reduced, but were very similar for sorbitol and xylitol gums (mean -Z: baseline, 2318; xylitol, 1877; sorbitol, 1888). This finding was confirmed by birefringence measurements. The results indicate that sorbitol and xylitol gums are nearly identical from their ability to enhance remineralization of experimental early enamel lesions.

The objective of the study was to determine quantitatively the effect on the potential for from situ remineralization of artificial caries-like lesions from human enamel when sugar-free gum containing mainly sorbitol as sweetener was chewed after meals and snacks. Artificial whitespot lesions were created from extracted human premolars and divided into three parts. One part was used as reference and the other two worn consecutively for two 21 day periods by 10 volunteers from a cast silver band cemented on lower molar teeth and covered using gauze to promote plaque formation. During the experimental periods, the subjects used fluoridated toothpaste twice-daily, and consumed three meals (breakfast, lunch and dinner) and two snacks (selected from chocolate bar, raisins, chocolate wafer, and iced cupcake). Sorbitol gum was chewed for 20 min immediately after each meal or snack during one of the experimental periods. The three parts of the enamel lesions were then sectioned ( 80 (m) and examined together by means of quantitative microdiography and by polarized light microscopy.

All estimates of mineral content indicated that significant remineralization occurred and was approximately doubled using gum-chewing. It is suggested that sorbitol gum stimulates salivation, which is responsible for the significantly enhanced reminalization, thus contributing to a therapeutic, caries-preventive effect. Because the gum was chewed immediately after meals and snacks, inhibition of demineralization may also have occurred.

Measurements were made of the effect of chewing sorbitol gum on the intra-oral demineralization induced by rinsing using 10% sucrose solutions. Blocks of bovine enamel were covered using a layer of Streptococcus mutans IB1600, and mounted on palatal appliances that were worn by five subjects for defined periods of time. Enamel demineralization was determined by following changes from iodide penetrability (delta Ip) of the enamel surfaces. Delta Ip increased to a maximum of about 15 units between 30 and 45 min, while the pH of the S. mutans plaque dropped to below 4 by 15 min. Plaque pH returned to 4.9 by 60 min. Chewing sorbitol gum after the sucrose rinse minimized further increases from delta Ip and brought about a more rapid return of the S. mutans plaque pH toward neutrality. The effect of chewing gum was greater when chewing was initiated earlier so that, when gum was given at five min after the sucrose rinse, demineralization was only 37% of that obtained without gum. The findings confirm earlier reports on the effect of gum on plaque pH, and directly demonstrate the profound protective effects that chewing sorbitol gum can have on tooth enamel.