Saddleback Journal of Biology - Saddleback College

Fall 2009 Biology 3B Paper
Results
Salivary pH. The presence of bicarbonate in
chewing gum had a pronounced effect on the
stimulated pH (Figure 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). 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, while control group reached
its peak during 4-6 min. 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 group.
The mean stimulated salivary pH values were
significantly greater at all times than the unstimulated
salivary pH (Post-Hoc, pairwise t-test, 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). The results for the
stimulated salivary pH are shown in Figure 1.
Salivary flow rates. The presence of bicarbonate in
chewing gum did not have an effect on the salivary
8.50
8.30
8.10
7.90
H
p 7.70
ry
a 7.50
liv
a 7.30
S
7.10
6.90
6.70
6.50
Control
Bicarb
-5 0 5 10 15 20 25 30
Time (min)
Figure 1. Salivary pH (Mean ± S.D.) obtained over a 30
minute period during chewing of either control gum (black
circles) or experimental gum (white diamonds), preceded by a
flow rates. (Figure 2) The mean unstimulated salivary
flow rates were 0.99 ± 0.37 mL/minutes for the control
gum and 0.86 ± 0.43 mL/minutes 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).The
peak salivary flows occurred in the first minute after
the onset of chewing, were 2.48 ± 0.80 mL/minutes 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). 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.
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 sodium bicarbonate group. Post hoc
comparisons between unstimulated and stimulated
interval at 15-20 min and 25-30 min, showed no
significant differences of salivary flow rates (pairwise
t-tests, 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 (twotailed
t-tests, P > 0.05). The results for the stimulated
salivary flows are shown in Figure 2.
3.0
)
in
m
/
L
(m
2.0
w
lo
F
ry
a
liv 1.0
a
S
0.0
Control
Bicarb
-5 0 5 10 15 20 25 30
Time (min)
Figure 2. Salivary flow rates (Mean ± S.D. mL/minute)
achieved over a 30 minutes period during chewing of either
control gum (black circles) or experimental gum (white
diamonds), preceded by a 2 minute collection of
Discussion
The experiment showed that while bicarbonate and
standard gums were equally effective in stimulating
salivary flow, the pH of the saliva was higher 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 less than those
reported for some other studies, but this may reflect
individual and procedural variations. 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).
118
Saddleback Journal of Biology
Spring 2010