Efficacy (efficiency) of Bicarbonate-containing Chewing Gum on the Salivary Flow and pH in Humans
Alvin Jogasuria and Eric Taysom
Department of Biological Sciences
Saddleback College
Mission Viejo, California 92692
Chewing gum increases salivary flow by gustatory and mechanical stimuli. The aim of this present study was (this study was) to compare the effect of bicarbonate chewing gum with the standard gum. Mouth saliva was collected from 12 participants who fulfilled inclusion criteria and gave verbal informed consent. Gum stimulated saliva was collected at various intervals during 30 min period of chewing (insert “either”) bicarbonate or standard gum. Salivary volume and pH were measured for each sample and subjected to single-factor ANOVA and paired t-tests. The mean stimulated flow rates were greater than the unstimulated flow rates at all times; however, the differences were only significant up to 10 min. The peak salivary flows for the control group were (The control group’s peak salivary flows were) 2.48 ± 0.80 mL/min and 2.42 ± 1.18 mL/min for the bicarbonate gum. The peak salivary pH values occurred later than (after) the peak salivary flow and were 7.70 ± 0.34 for the control gum and 8.00 ± 0.33 for the bicarbonate gum. Throughout the experiment, the pH of the bicarbonate gum-stimulated saliva was higher than the pH of the saliva evoked by chewing the standard control gum (two-tailed t-tests, P ≤ 0.05). Both gums were effective in stimulating salivary flows (insert “however”), the pH of the saliva was greater with the bicarbonate gum. The higher salivary pH achieved with chewing bicarbonate gum may have important oral health implications and prevention of dental caries. (Rephrase this. It’s a weird ending to an abstract. This kind of statement should be more towards the beginning, referring to why you decided to begin this study.)
Introduction
Saliva has an important role in maintaining oral health. Saliva accomplishes its mechanical cleaning and protective functions through various physical and biochemical mechanisms. Saliva also has a buffer capacity (insert “,”) which neutralizes acids in the mouth. The carbonic acid and bicarbonate system is the most important buffer in stimulated saliva due to its higher concentration (Legier-Vargas 1995). The values of the bicarbonates in saliva may serve as parameters for determining the caries risk patients and allow dentists to take appropriate measures to prevent caries formation. Chewing gum is one convenient way to increase salivary flow. It has been well known that both gum chewing and sodium bicarbonate are beneficial to oral health and the two have been combined in a bicarbonate containing gum. Chewing gum increases salivary flow in two ways. (Insert “:” instead of a period and lowercase “it”. Insert “, and” after the upcoming citation and lowercase “it” again) It increases flow by gustatory (taste) and mechanical (mastication) stimuli (Legier-Vargas 1995). It also increases salivary and plaque pH, and chewing gum can provide an innovation for delivering medicaments such as chlorohexidine, enzymes, fluoride and whitening agents (Dawes and Macpherson, 1992). It has been shown that chewing flavored gum will increase rate of salivary flow initially, but declines (insert “that rate”) as the flavoring is lost from the gum (Dawes and Macpherson, 1992).
(insert “The” and lowercase “key”) Key ingredient of baking soda, NaHCO3, was used originally in toothpaste as an abrasive (Legier-Vargas 1995), but now it can be used to act as a base by neutralizing plaque acid (Dawes 1997). Chewing bicarbonate gum would be expected to increase salivary pH as bicarbonate ions leach out from the gum. After the onset of chewing bicarbonate gum, the pH of the saliva would increases (increase), but unlike the flow rate, it remains elevated after 15 min of stimulation (Dawes 1969). The objective of this present study was to measure the rate of salivary flow and the pH produced during a 30 min periods (period) of chewing bicarbonate-containing gum and to compare the results with a 30 min period of chewing non-bicarbonate-containing gum as the standard (control).
Materials and Methods
The experiments were tested on 12 volunteers (7 males, 5 females) aged 17 - 25 years (you shouldn’t have any minors in your study), who fulfilled these inclusion criteria and were able to give verbal informed consent. Eligible volunteers had to be non-smokers and have no significant oral or systemic disease; not taking any medication that interfere with saliva production; not under physician's care; not wearing orthodontics appliances nor having an allergy to the ingredients of the chewing gum (Use a “:” after “disease” and commas after each criteria). Prior (insert “to the”) collection period, participants were instructed to refrain from consuming any food or drink at least 1 hr (one hour) prior (insert “to the”) investigation and to abstain from alcoholic beverages for the previous 12 hours.
Two types of chewing gum purchased from a local grocery store were used in this experiment. The control gum was sugar-free, wintermint-flavored (regular Orbit) and the experimental gum was sugar-free, spearmint-flavored gum, bicarbonate containing gum (Orbit White). Both gum (gums) are manufactured by the Wrigley Company Ltd, Chicago, IL 60611. Both pellets were similar in volume and mass. The average volumes and masses of the experimental and control gum pellets were 1.3 and 1.4 cm3; 1.54 and 1.58 g. During investigation, each gum was unmarked and indistinguishable to the test subject.
Subjects were seated comfortably in the lab room and allowed to roam around the lab. Both unstimulated and stimulated whole mouth saliva collection process were monitored for a total collection period of 1 hr and 20 m. (huh?) The volume of saliva and pH measurements were taken with (insert”a”) 10-mL graduated cylinder (insert “with”) plastic funnel attachments and PASCO High Precision pH probe instruments (Pasco Scientific, Roseville, CA). Gum stimulated saliva was collected at intervals of 0-1, 1-2, 2-4, 4-6, 7-10, 15-20, and 25-30 minutes. Unstimulated saliva was collected over a 2 min period. During collection intervals, participants were asked to dribble their saliva into a plastic funnel. During the non-collection period, subjects were allowed to swallowed (swallow) their saliva. Measurements of the salivary volume and pH were taken immediately after the collection period to avoid time-based pH changes. Within 10 seconds after collection of the sample, the volume was obtained by measuring to the top of the meniscus using the graduations on the graduated cylinder, with accuracies up to 0.1 mL. The pH was then measured using (insert “a”) pH probe calibrated at the factory for a pH slope of -0.059 mV per pH unit and zero at a pH of 7, with accuracies of 1.0 pH unit or better may (to) be expected.
The same protocol was then repeated for the second gum sample. It was done on the same day after a 20 minutes break period. Break period will allow (insert “the”) subject's salivary flow rates and pH to return to the basal levels. Each subject was tested on the same day rather than on separate days in order to avoid possible effects of circadian rhythms in salivary flow rate (Dawes 1992). The investigation was performed at the Saddleback College Biology Lab, Mission Viejo, CA. The samples (n=11) were collected on November 6, 2009, with appointments started from (starting at) 9 (9:00) am to (and continuing until) 1 pm (1:00 pm). There was one sample taken separately on November 3, 2009 at 12 - 1:20 pm (12:00 pm until 1:20 pm).
Measurements were entered into a database (Microsoft Excel, 2007) and analyzed by the General Linear Model of ANOVA using a single factor design. MegaStats, a free Excel's (Excel) Add-ins, was used to calculate (insert “the”) ANOVA values. Salivary flow and pH data within each of the control and experimental group were analyzed with (insert “a”) single-factor ANOVA. Post-Hoc analysis, pairwise t-tests, were calculated when P ≤ 0.05 (p≤0.05). Two-tailed paired t-tests were used to compare the stimulated flow and pH data of the control group and the experimental group. Differences were considered significant at P ≤ 0.05 (p≤0.05).
Results
Salivary flow rates. The presence of bicarbonate in chewing gum didn't (did not) have an effect on the salivary flow rates. The mean unstimulated salivary flow rates were 0.99 ± 0.37 mL/min for the control gum and 0.86 ± 0.43 mL/min for the bicarbonate gum. There were no significant differences between the unstimulated salivary flow rates between the two types of gum (two-tailed t-test, P = 0.1974, P 0.05 (p=0.1974, p>0.05)). The peak salivary flows occurred in the first minute after the onset of chewing, (insert a period after “chewing” and then continue with “Their values…”) were 2.48 ± 0.80 mL/min for the control gum and 2.42 ± 1.18 mL/min for the bicarbonate gum. There were no significant differences between the stimulated salivary flow rate of the control and bicarbonate gum (two-tailed t-tests, P = 0.8760, P > 0.05 (p=0.8760, p>0.05)). The mean stimulated flow rates for the bicarbonate gum and control gum were greater than the unstimulated flow rates at all times; (,) however, the differences were only significant up to 10 min (minutes). Analysis of variance indicated significance among stimulated and unstimulated data set within the groups, p= 4.19 × 10-6 for the control group and p= 1.17 × 10-6 for the bicarb(onate) group. Post hoc comparisons between unstimulated and stimulated interval at 15-20 min (minutes) and 25-30 min (minutes), showed no significant differences of salivary flow rates (pairwise t-tests, P > 0.05 (p>0.05)). Finally, there were no significant differences between the salivary flows evoked by the two types of gum at any of the time intervals (two-tailed t-tests, P > 0.05 (p>0.05)). The results for the stimulated salivary flows are shown in Figure 2.
Salivary pH. The presence of bicarbonate in chewing gum had a pronounced effect on the stimulated pH (Fig(ure) 1). The mean unstimulated salivary pH was 6.94 ± 0.42 for the control gum and 6.97 ± 0.28 for the bicarbonate gum. As with the flow rates, there were no significant differences between the two sets of unstimulated salivary pH values between the control and bicarbonate gum (two-tailed t-test, P = 0.8298, P 0.05 (p=0.8298, p>0.05)). The peak salivary pH values occurred later than the peak salivary flow and were 7.70 ± 0.34 for the control gum and 8.00 ± 0.33 for the bicarbonate gum. The peak pH for the bicarbonate group occurred two minutes earlier after onset of chewing, during 2-4 min (minutes), while control group reached its peak during 4-6 min (minutes). Analysis of variance indicated significance among the unstimulated and stimulated data sets within the groups, p= 1.20 × 10-3 for the control group and p= 6.37 × 10-11 for the bicarb(onate) group. The mean stimulated salivary pH values were significantly greater at all time(s) than the unstimulated salivary pH (Post-Hoc, pairwise t-test, P ≤ 0.05 (p≤0.05)). Throughout the experiment, the pH of the bicarbonate gum-stimulated saliva was higher than the pH of the saliva evoked by chewing the standard control gum (two-tailed t-tests, P ≤ 0.05 (p≤0.05)). The results for the stimulated salivary pH are shown in Figure 1.
Discussion
The experiments (This experiment) showed that while bicarbonate and standard gums were equally effective in stimulating salivary flow, the pH of the saliva was greater with the bicarbonate gum. The mean salivary flows for both types of gum and the mean pH response for the standard gum confirm findings previously reported (Dawes 1992). The peak salivary flow rates recorded in the present experiments were rather were rather (insert “much” or “far”) less than those reported for some other studies, but this may reflect individual and procedural variations. The amount of gum chewed (one pellet) was smaller than has been used in many previous studies, but the single pellet was chosen as it would represent the worst (insert “-“) case experimental scenario (why?). However, in the view of the participants, this was a realistic test of natural chewing conditions. In addition, participants were allowed to chew gum at their own, preferred rate, rather than having the chewing with a metronome. This lack of control of the chewing frequency should not have unduly influenced the results, as it has been shown that salivary flow rates are affected more by the mass of the gum sample than chewing frequency (Rosenhack, et al., 1993; Dawes and Puckett, 1995).
The peak pH of bicarbonate-stimulated saliva was greater than that produced by chewing the standard gum at all times. It represents a decrease in the hydrogen ion concentration of the whole mouth saliva, thus yields greater pH value. The salivary bicarbonate concentration is known to increase with increasing flow rate (Dawes 1969). The bicarbonate concentration of gum-stimulated saliva has been reported to increase from an unstimulated value around 4mM to a peak of 15mM when chewing a 3(no space, “3g” or “3 gram”) g gum sample (Rosenhack, et al, 1993). The latter study increase the bicarbonate concentration was very similar to the increase in salivary pH observed in the present experiment. It is thus likely that the rise in salivary pH was linked to an increase in salivary bicarbonate concentrations. The bicarbonate gum pellets contain 3% sodium bicarbonate, and it is most likely that the additional increase in salivary pH with the bicarbonate gum was due to bicarbonate ions leaching out from the gum. As this reservoir diminishes with time, the differences in pH of the saliva stimulated by each gum will decreases. The rate at which (insert “the”) gum(’s) ingredients enter the saliva has been estimated by measuring the salivary sucrose levels in participants chewing sucrose-containing gum (Rosenhack, et.al., 1993). It was found that most of the sucrose was lost over 10-15min(minutes), depending on the size of the sample (Rosenhack, et.al., 1993). These data are not consistent with the time course of the salivary pH changes induced by chewing bicarbonate gum in the present experiment (Fig(ure).1). This study presents new findings that the bicarbonate chewing gum delayed the lost of bicarbonate by approximately 10 min(utes), over 20-25 min(ute) interval(s). The higher salivary pH achieved with chewing bicarbonate gum, compared to a standard, sugar-free gum, may (why “may”? you should end on a strong note, this is not a strong concluding sentence) have important oral health implications.