Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
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. 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 the rate
of salivary flow initially, but declines as the flavoring
is lost from the gum (Dawes and Macpherson, 1992).
A Key ingredient of baking soda, NaHCO 3 , 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 increase, but unlike the flow
rate, it remains elevated after 15 minutes of stimulation
(Dawes 1969). The objective of this study was to
measure the rate of salivary flow and the pH produced
during a 30 minutes periods of chewing bicarbonatecontaining
gum and to compare the results with a 30
minutes period of chewing non-bicarbonate-containing
gum as the standard.
Materials and Methods
The experiment was tested on 12 volunteers (6
males, 5 females) aged 18 - 25 years, who fulfilled the
inclusion criteria, which is described below, 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, or not wearing orthodontics
appliances nor having an allergy to the ingredients of
the chewing gum. Prior collection period, participants
were instructed to refrain from consuming any food or
drink at least 1 hour prior 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 that contained sodium
bicarbonate (Orbit White). Both gums are
manufactured by the Wrigley Company Ltd, Chicago,
IL 60611. Both pieces of gum were similar in volume
and mass. The average volumes and masses of the
experimental and control gum pellets were 1.3 cm 3 and
1.4 cm 3 ; 1.54g and 1.58 g respectively. During
investigation, each gum was unmarked and
indistinguishable to the test subject.
Subjects were seated comfortable in the lab room
and allowed to roam around the lab. Both unstimulated
and stimulated whole mouth saliva collection were
monitored for a total collection period of 1 hour and 20
minutes. The volume of saliva and pH measurements
were taken with a 10-mL graduated cylinder 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 minute
period. During collection intervals, participants were
asked to dribble their saliva into a plastic funnel.
During the non-collection period, subjects were
allowed to 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 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 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 allowed
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 9 am to 1 pm.
There was one sample taken separately on November
3, 2009 at 12 - 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.
Megastat, a free Excel’s Add-ins, was used to calculate
ANOVA values. Salivary flow and pH data within each
of the control and experimental group were analyzed
with a single-factor ANOVA. Post-Hoc analysis,
pairwise t-tests, were calculated when (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).
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Saddleback Journal of Biology
Spring 2010