Perio Reports Vol. 25, No. 3 |
Perio Reports provides easy-to-read research summaries on topics of specific
interest to clinicians. Perio Reports research summaries will be included in each
issue to keep you on the cutting edge of dental hygiene science.
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Four Steps to Identify Early Salivary Gland Hypofunction
The importance of saliva to oral and overall health is
often overlooked by those outside the dental profession.
Saliva is important for protection of hard and soft tissues,
enamel mineralization and remineralization and digestion.
Xerostomia is the subjective feeling of dr y mouth and
hyposalivation is the objective measure of salivary flow.
Aging is not responsible for reduced salivary flow, but the
medications taken by the elderly do cause xerostomia.
The following four steps help clinicians detect early signs
of salivary gland hypofunction. First, ask questions about
dry mouth with a visual analog scale for scoring: Do you
have too much or too little saliva in your mouth? Do you
have difficulty swallowing? Does your mouth feel dry while
eating? Do you sip liquids to help swallow dry foods?
Second, review medical history and body systems. Sjogren’s
syndrome, rheumatoid arthritis, scleroderma, hypothyroidism,
depression and eating disorders all impact salivary flow.
Tobacco, alcohol and drug use will all affect salivary flow.
Third, complete a thorough clinical evaluation. How
does the patient appear to you? Examine and palpate the
salivary ducts. Are they enlarged or tender? Can you elicit
saliva with palpation? Does the saliva pool? Visually check
oral tissues for dryness. Use a tongue blade against the buccal
mucosa to test for dryness. Check hard tissues for caries.
Look at the lips for signs of dr y, chapped or fissured appearance.
Is the tongue dry, er ythematous, lobulated or fissured?
Fourth, based on findings of the first three steps, further
diagnostic tests may be needed. These tests range from
measuring salivary flow to surgical biopsy
of a salivary gland.
Clinical Implications: Several clinical
steps provide valuable information in
detecting salivary gland hypofunction.
Navazesh, M.: How Can Oral Health Care Providers Determine if Patients
Have Dry Mouth? JADA 134: 613-620. 2003.
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Measuring Saliva in Clinical Practice
Biomarkers in saliva provide diagnostic information on
oral, ovarian and breast cancer; HIV infection; Sjogren’s
Syndrome; and dental caries and periodontal disease. Saliva
is also used to measure alcohol and illegal drug use and nicotine
and cotinine levels associated with tobacco use.
Physiologic changes associated with pregnancy and depression
can also be detected in saliva.
Saliva collection can be from one or a mixture of glands
and stimulated or unstimulated. Major salivary glands provide
90 percent of saliva, with minor glands providing the remaining
10 percent. Whole saliva is contaminated with food,
micro-organisms and gingival crevicular fluid and consists of
99 percent water and one percent proteins and salts. Total
daily output is between 0.5 liters and 1.5 liters. Minor salivary
glands provide lubrication and protection for mucosal tissues.
Unstimulated saliva is primarily from the submandibular
glands and is both serous and mucous in nature. Stimulated
saliva is from the parotid gland primarily and is completely
serous in nature. The sublingual gland contribution to either
stimulated or unstimulated saliva is minimal.
Reduced salivary flow negatively impacts the quality of
life by causing difficulty with speaking, eating, swallowing
and tasting. Objective measures are needed to accurately
determine xerostomia. Salivary flow is simulated with gum
base, paraffin wax, rubber bands and citric acid, and is collected
by the patient spitting all saliva into a collection
cup. Unstimulated salivary flow is collected from the mouth
by having the patient tip his or her head forward and with an
open mouth, allowing all salvia to run out of the mouth and
into the collection container.
Clinical Implications: Dental practices have a variety of clinical means to measure salivary flow.
Navazesh, M., Kumar, S.: Measuring Salivary Flow: Challenges and Opportunities. JADA 139; (suppl 2): 35S-40S, 2008.
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Salivary Flow Rates in the Elderly
Dry mouth is reported by elderly patients, but is
not necessarily related to hyposalivation. Subjective
feelings of dryness are reported in some who have
normal salivary flow rates.
Researchers at the University of Helsinki in
Helsinki, Finland, evaluated a group of 368 elderly
people. This was a subgroup of a larger medical study
of the elderly. Both stimulated and unstimulated salivary
samples were collected from the group, however,
some of the subjects showed signs
of motor and cognitive impairment
so samples were collected
from 60 subjects for each of the
saliva tests. They were also interviewed
and asked 14 questions
about oral dryness and dryness of
the throat, eyes, nose and skin.
Of this group, 46 percent
complained of some oral dryness.
Continuous dry mouth was
reported by 12 percent of the
group. Others reported dry mouth in the morning
(36 percent), during the day (19 percent) and in the
evening (16 percent). Common complaints were
dryness while speaking, taste impairment, difficulty
swallowing dry foods and dry lips. Extra-oral dryness
was reported for dry eyes and dry skin. More
women than men reported dry mouth symptoms.
Waking up at night to drink was reported by 34
percent. It was not just water that they drank, but also
juice, soft drinks, milk and beer. This may be a significant
factor in caries risk among the elderly. Those
taking medications also reported more oral dryness.
Mouth breathing causes evaporation of saliva, leading
to dry mouth and increasing risk of caries.
Clinical Implications: Look for dry mouth more
frequently in women, those who mouth breathe
and those who take medications.
Narhi, T.: Prevalence of Subjective Feelings of Dry Mouth in the Elderly. J Dent Res 73(1):
20-25, 1994..
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Clinical Signs that Predict Low Salivary Flow Rates
Salivary gland hypofunction leads to several problems
including caries, periodontitis, mucositis, angular cheilitis
and altered taste. “Dry mouth” was first described in the literature
in 1868 and xerostomia in 1889. It wasn’t until 1967
that standardized methods for measuring
salivary flow rates were introduced in a study
of 50 patients with xerostomia. In 1987 it
was reported that questions about dry
mouth helped identify those who needed
further salivary tests.
Researchers at the University of
Pennsylvania School of Dental Medicine
designed a study to compare subjects with
and without normal salivary flow. The group
consisted of 23 men and 48 women ranging
in age from 19 to 82 years, the average being
52 years. Subjects underwent the tests three times at different
times during the day, to take into account the influence
of circadian rhythm. A total of 64 measures were taken on
each patient, each time. Measurements were taken for lip
dryness, buccal mucosa dryness, salivary pooling, salivary
gland palpitation, tongue, periodontal tissues and total
DMFT. Salvia collection included stimulated and unstimulated
whole saliva. Additionally, saliva samples were collected
from right and left parotid glands.
A diagnosis of salivary gland hypofunction relies on salivary
flow rate measures. This study demonstrated that other
measures could reliably predict those who will have salivary
hypofunction, but not the cause of the hypofunction.
Together lip dryness, buccal mucosa dryness, salivary gland
palpation for flow and DMFT scores successfully identified
those with low salivary flow test scores.
Clinical Implications: Together, checking dryness of the
lips and buccal mucosa, total DMFT and absence of
saliva with gland palpitation are accurate signs of salivary
gland dysfunction.
Navazesh, M, Christensen, C., Brightman, V.: Clinical Criteria for the Diagnosis of Salivary Gland
Hypofunction. J Dent Res 71 (7): 1363-1369, 1992.
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Salivary Clearance of Sugar from the Mouth
Salivary clearance of sugar from the mouth is
important for reducing risk of dental caries. Previous
researchers studied the changes in the total volume
of saliva secreted in response
to 2mL of acid held in
the mouth for one minute.
What they were unable to
determine was if the salivary
flow rate changed during
the exposure to the acid.
Researchers at the
University of Manitoba in
Winnipeg, Canada devised
a method to measure flow
rate changes in saliva when
the subject was exposed to sugar, sodium chloride or
citric acid. Twelve young adults, six men and six
women participated in this study. Saliva flowed from
the subject’s mouth into a funnel beaker that sat on
a balance that measured each 0.01mL increase in the
salivary flow rate.
The three test tastes were introduced in a fluid
state and removed immediately over an exposure
time of three minutes, followed by a washout period
using only water until salivary flow rate stabilized. A
rest period of five minutes was allowed between
tests. A high and a low concentration were tested for
each taste, providing six tests per subject.
The delay between the taste stimulation and
maximum salivary flow rate was 9.4 seconds. From
this point, the flow rate half-life was determined to
be 11 seconds even though the taste stimulation
continued for three minutes. There were no statistically
significant differences in salivary flow rates
between the three tastes tested. Regarding sugar,
taste adaptation reduces salivary flow rates, thus
slowing clearance of the sugar.
Clinical Implications: These findings show full salivary
clearance of sugar takes 25 to 45 minutes.
Dawes, C., Wantanabe, S.: The Effect of Taste Adaptation on Salivary Flow Rate and
Salivary Sugar Clearance. J Dent Res 66(3): 740-744, 1987.
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The Importance of Saliva in Preventing Caries
Enamel will demineralize at a pH of 5.5, dentin at a pH
of six. Plaque pH drops below 5.5 within three minutes of
exposure to sucrose, flour or other fermentable carbohydrates.
Saliva is responsible for returning the plaque pH to a
level that does not lead to enamel demineralization. Reduced
salivary flow results in a great drop in plaque pH and a longer
recovery time. Besides neutralizing the acids produced in
plaque biofilm, saliva has the ability to remineralize enamel
or dentin that has been demineralized. In 1966 Dr. Backer
Dirks reported on 70 seven-year-old children with a total of
72 white spots lesions that were monitored over eight years.
Of these lesions, nine progressed to cavitation, 26 were
arrested and unchanged and 37, more than half, were remineralized
and no longer detectable clinically.
The increased prominence of sugar- and flour-containing
foods is a risk for dental caries, but food alone is not responsible.
Stimulated saliva is instrumental in elevating the pH of
plaque. Saliva contains bicarbonate and the concentration
increases with prolonged stimulation of salivary flow, favoring
elevation of the pH and remineralization of enamel
rather than demineralization.
Several studies demonstrate the value of chewing sugarless
gum after meals to stimulate salivary flow and elevate
plaque pH. Sorbitol-sweetened chewing gums are not always
better than no-gum groups but have been reported to reduce
caries from zero to 20 percent while xylitol-sweetened gums
reduce caries 43 to 71 percent, depending on dose and daily
frequency, three versus five exposures each day. Stimulation
of salivary flow from gum chewing plus xylitol reduces caries
rates significantly.
CClinical Implications: Stimulating salivary flow after eating can reduce the incidence of dental caries.
Stookey, G.: The Effect of Saliva on Dental Caries. JADA 139: 11S-17S, 2008. |