Perio Reports Vol. 26, 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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How Many Times Do You Swallow Every Hour?
Swallowing frequency varies widely among individuals.
Exactly what initiates the swallowing reflex is unknown. It
might be related to the amount of saliva accumulating or
when saliva reaches specific receptors. The absolute size of
the oral cavity will influence how much saliva accumulates
and how soon it reaches receptors. Measuring how often
someone swallows is difficult as the person knows the swallows
are being measured and they become more aware of
them and perhaps bias the results.
Researchers at the University of Minnesota evaluated
128 first-year dental students to determine the relationship
between saliva flow and frequency of swallowing. The group
consisted of 76 males and 52 females. A microphone was
taped to the neck, near the larynx, to record swallowing
noises. Subjects were asked to sit quietly and read for 30
minutes and push a button every time they noticed themselves
swallowing.
To estimate saliva volume swallowed, subjects were
asked to swallow and then hold the saliva in their mouth for
their par ticular average time between swallows and then
expectorate all the saliva into a tube. This was repeated four
times for each individual.
The average number of swallows per hour was 122, with
a range of swallows per hour from 18 to 400 – quite a wide
variation. Saliva flow was greater in males compared to
females. Those who swallowed frequently had high flow
rates with small saliva volumes. Those who waited a long
time between swallows had low flow rates with high volume.
Clinical Implications: The number of
times a person swallows each day depends
on saliva flow and volume.
Rudney, J., Ji, Z., Larson, C.: The Prediction of Saliva Swallowing Frequency
in Humans from Estimates of Salivary Flow Rate and the Volume of Saliva
Swallowed. Arciv Oral Biol 40:(6) 507-512, 1995.
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How a Person Swallows Impacts Dentofacial Development
There is much debate in the orthodontic community
about the influence of the tongue on facial development.
Some believe the tongue muscle function influences bone
and jaw development while others believe the tongue merely
adapts to the genetically predetermined oral environment by
changing swallowing and speech patterns to fit. If the tongue
muscle does in fact exert forces on bone through abnormal
swallowing patterns, this should be taken into consideration
before beginning orthodontic treatment, to prevent relapse.
Researcher in Taipei, Taiwan evaluated 112 adults during
swallowing to determine the impact on dentofacial morphology.
They used computer-aided ultrasonography, cephalometreic
radiography and study models. The cushion scanning
technique (CST) used a framework that the patient leaned
his/her forehead against and a cushion under the chin and on
the front of the throat that did not interfere with swallowing.
Swallowing was divided into five phases, depending on
which part of the tongue was in contact with the palate.
Swallowing was done with saliva only.
There was significant correlation between tongue movements
during swallowing and the structure of the face and
jaw. Swallowing for a longer time when the back of the
tongue contacted the palate, the end of swallowing, led to
increased arch length and increased palatal depth.
Despite significant correlations, they failed to show a
cause-and-effect relationship between swallowing and dentofacial
form. More factors need to be considered together with
swallowing, including genetics, other forces from the lips and
cheeks, resistance of the teeth and alveolar arch and resting
posture of the tongue.
Clinical Implications: The relationship between the teeth, tongue, bone and development is both complex and inconclusive.
Cheng, C., Peng, C., Chiou, H., Tsai, C.: Dentofacial Morphology and Tongue Function During Swallowing. Am J Orthod Dentofacial Orthop 122: 491-9, 2002.
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Maxillary Lip-tie Can Impede Breastfeeding
Breastfeeding requires that the infant can successfully latch
onto mother’s breast. The primary oral condition preventing
this is ankyloglossia or tongue-tie. Another area to be checked
is the attachment of the upper lip to the maxillary gingival tissues.
Historically this has had several names: labial frenum,
median labial frenum and maxillary labial frenum.
The attachment of the upper lip to the anterior maxillary
arch is loose connective tissue. It is not attached to bone and
there is no muscle within this
tissue. In severe cases, this
frenum is attached around the
maxillary arch and into the
incisive papilla.
The lip-tie restricts movement
of the upper lip and can
make latching onto the breast
difficult for the infant. To
latch on properly, the infant
must be able to suckle both the nipple and the areola. Taking
only the nipple into the mouth may be painful for the mother
and cause irritation to the nipple tissue. The baby’s lips and
cheeks are part of creating a good seal to allow adequate milk
to be suckled from the breast. The nipple must be positioned at
the junction of the hard and soft palates, otherwise the gum
pads of the infant compress the nipple. Loud clicking sounds
means the infant is sucking in air.
Various degrees of lip-tie and tongue-tie exist, some slight
and others severe. When breastfeeding problems arise and the
infant fails to thrive, the labial and lingual frenums should be
checked and surgically corrected to allow for comfortable and
effective breastfeeding.
Clinical Implications: Both tongue-tie and lip-tie will interfere
with successful breastfeeding.
Kotlow, L.: Diagnosing and Understanding the Maxillary Lip-tie (Superior Labial, the Maxillary Labial
Frenum) as it Relates to Breastfeeding. J of Human Lactation 29(4): 1-7, 2013.
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Maxillary Frenums Linked to Caries in
Breastfeeding Infants
In years past, first dental
visits for children were at age
three, and now the Academy
of Pediatric Dentistry recommends
seeing children by
their first birthday or within
six months of the first tooth
erupting. Children, as young
as six months, can develop early infant dental caries.
In 1977 it was reported that infants exclusively
breastfeeding, sleeping next to the mother and
engaging in at-will nursing developed caries on the
anterior teeth. Lower anterior teeth are protected
from caries formation in infants as the normally
functioning tongue will rest over these teeth.
While rare, breastfeeding-induced dental caries
is associated with a tight maxillary frenum.
Immediately after nursing, inspection of the maxillary
teeth will show evidence of retained milk. The
tight maxillary frenum is also seen in cases of early
childhood caries when there is no history of breastfeeding
or sleeping with a bottle.
A pediatric dentist, evaluated 350 infants from
newborns to three year olds and developed a classification
system for maxillary frenums. Class I is little
or no frenum attachment. Class II is a frenum
attachment at or above the mucogingival margin.
Class III is at or into the interproximal space
between the central incisors. Class IV is a frenum
that wraps around to the lingual, attaching to
palatal tissue.
Caries is most often associated with frenums of
Class III and IV. Revision of the maxillary frenum
can be done in the dental office using a laser.
Clinical Implications: Both maxillary and lingual
frenums should be checked in newborns
and when teeth erupt.
Kotlow, L.: The Influence of the Maxillary Frenum on the Development and Pattern of
Dental Caries on the Anterior Teeth in Breastfeeding Infants: Prevention, Diagnosis, and
Treatment. J Human Lactation 26: 304-308, 2010.
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Swallowing Air Causes Problems for Newborns
When a newborn is unable to breastfeed due to
inadequate latching onto the breast, problems arise.
Clicking sounds and nipple pain may indicate inadequate
attachment to the breast. This can lead to failure
to thrive, prolonged or frequent
breastfeeding with poor milk transfer,
colic and reflux. Problems for
the mother include plugged ducts,
pain, flattened, compressed or
injured nipples and mastitis.
Aerophagia, directly translated
from Greek means to “eat air.”
Infants experiencing problems with
breastfeeding often swallow air. This causes abdominal
distention, belching and flatulence. Colic, crying
and screaming frequently for long periods of time,
can happen in an otherwise healthy baby. Reflux or
GERD are also seen in infants, producing intense
pain and discomfort.
Tight maxillary lip-ties and ankyloglossia can be
the cause of some of these problems. These tight
attachments of lip and tongue can prevent successful
breastfeeding, leading to the infant swallowing air and
not getting enough milk.
More than 50 infants were treated with revisions
of lip-tie and tongue-tie resulting in a significant
reduction or total elimination of the symptoms of
reflux. Many of the infants had suffered for several
months, as had their parents being unable to console
their newborn babies. Physicians recommended a battery
of tests and prescribed medications for the
infants. In some cases, breast milk was blamed for the
problems, but switching to a bottle formula did not
resolve the symptoms. Surgical revision of these lipand
tongue-ties allowed for successful latching on and
breastfeeding.
Clinical Implications: Infants suffering from colic
or reflux symptoms may benefit from a dental
examination to check for lip-tie and tongue-tie.
Kotlow, L.: Infant Reflux and Aerophagia Associated with the Maxillary Lip-tie and
Ankyloglossia (Tongue-tie). Clinical Lactation 2(4):25-29, 2011.
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Horizontal Brushing for Deciduous Teeth
Toothbrushing or the lack thereof is considered a caries
risk factor. Toothbrushing effectiveness is determined by both
frequency and technique. Several techniques are taught to
children. The scrubbing technique involves simple horizontal,
vertical or circular movements. More complex movements are
taught in the Bass technique or the roll method. National and
international dental associations make varying recommendations
for method and frequency on their websites.
Researchers in Paris, France performed a systematic
review of randomized controlled studies of toothbrushing
effectiveness based on method and frequency. Plaque scores
were the measurement used to determine effectiveness. Of
534 articles that appeared in their search, they identified six
studies to include in their analysis.
Two studies focused on deciduous teeth and consistently
showed the horizontal technique superior to the roll technique.
This was true when either the child or the parent did
the brushing. In mixed dentition, the horizontal technique is
more effective performed by the parent rather than the child.
In late mixed dentition, there was no difference between
three toothbrushing methods: horizontal, Bass and roll.
None of the studies measured the effect of frequency.
When dental association websites were analyzed, the
U.S. and European sites did not recommend a particular
toothbrushing method, but did recommend twice-daily
brushing. France recommends the horizontal method for
those under six years of age, an intermediate method for ages
six to eight and the roll method for those over nine years of
age. In New Zealand, the Bass method is recommended in
general and the horizontal method for children.
Clinical Implication: The horizontal scrub method works best for children, with modifications of the Bass method for
permanent dentition.
Muller-Bolla, M., Courson, F.: Toothbrushing Methods to Use in Children: A Systematic Review. Oral Health Prev Dent 11: 341-347, 2013.
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