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1. TechniqueTips
80 DentalUpdate January 2018
Technique Tips: The Use of a Novel Primary
Impression Technique in a Patient with Microstomia
The prevalence of edentulous patients has
decreased in Western society. The Adult
Dental Health Survey determined that the
level of edentulism reduced from 13% to 6%
between 1998 and 2009.1
There appears to
be a changing pattern in oral health status
as patients are retaining their natural teeth
for longer, meaning that dentists are no
longer making the same number of complete
dentures as our predecessors, and may be
becoming deskilled. Therefore, when faced
with complex patients requiring complete
denture construction, dentists may feel out of
their comfort zone and in need of improved
knowledge and skills.
Microstomia describes a
reduction of oral aperture,2
which may
be congenital or acquired. It may be a
consequence of conditions including
post-surgical and radiotherapy, trismus,
cleft lip and palate, trauma, scleroderma,
temporomandibular joint disorder, Plummer-
Vinson’s syndrome, oral submucous
fibrosis or damage to the muscles of
mastication.3
Microstomia makes all
dental treatment more difficult, especially
during prosthodontic impression taking,
and prosthesis construction may even be
rendered impossible. Alternative techniques
include modifications to small stock trays by
sectioning, or using children’s stock trays.4
This report describes the
prosthetic management of a patient suffering
from extensive post-surgical circumoral
stenosis and acquired microstomia which
rendered denture construction extremely
challenging. An innovative strategy was
required for recording primary impressions,
when the smallest stock trays available
were too large to fit intra-orally. Impression
compound was adapted to an articulator bite
fork to record a primary upper impression.
Case report
A 75-year-old female attended as
a new patient requesting upper and lower
complete dentures. Her expectations of
treatment were the restoration of function
and aesthetics and reduction of saliva
drooling.
The patient had an initial
diagnosis of a basal cell carcinoma (BCC) at
the inner canthus of her right eye 22 years
previously. This was surgically removed,
eliminating her tear duct. Over the next 20
years she experienced not only a recurrence
of the original BCC, but also a further 11
BCCs affecting both right and left temples,
lips, neck, back and legs. On each occasion
she underwent surgery to remove the BCC.
In November 2014, she was diagnosed with
11 BCCs simultaneously, and underwent 7
months of chemotherapy. In August 2015,
she underwent further facial surgery. She
is a life-long non-smoker, rarely drinks
alcohol and had no other relevant medical
history or history of excessive sun exposure
to account for the numerous BCCs. After
further consideration of the patient’s
unexplained multiple BCCs, perhaps this is a
case of Gorlin-Goltz syndrome. Gorlin-Goltz
syndrome is also known as Nevoid Basal Cell
Carcinoma syndrome and comprises a rare
genetic predisposition to BCCs.5
The patient had been edentulous
for several decades, with a history of wearing
complete dentures. However, she was unable
to wear dentures since her initial surgery
in 2014 as her microstomia meant she was
unable to insert them.
On examination, extra-orally,
she had post-surgical oral stenosis, deficient
nasal septum and incompetent lips (Figure 1).
Intra-orally she was edentulous with acquired
microstomia. The maximum vertical mouth
opening was measured to be 22 mm (Figure
2), compared to the average maximum
mouth opening of 41 mm for females.4
Figure
3 shows the patient’s atrophic lower alveolar
ridge and labial sulcus.
On attempting to record primary
impressions, even the smallest stock tray
available was too large for her mouth.
Impression compound was subsequently
adapted around the bite fork of an articulator
and was successfully used to record a
preliminary impression. Functional extension
of the compound was defined in the sulci by
gentle border moulding as the soft tissues
were very tender. Border moulding was
challenging due to severe fibrosis. Impression
compound was preferable to alginate due to
improved control of flow and ability to make
minor adjustments. The impression consisted
of multiple placement of compound with
selective warming to pick up detail and
correct errors. The metal bite fork held heat
and consequently the compound remained
fluid (malleable) for longer. It needed to
be in the mouth for longer to cool and
become firm. Also the fork provided a base
but no lateral support, so border moulding
was more complex than with a stock tray.
In terms of inserting the bite fork into the
patient’s mouth, one arm was placed in,
then the other was rotated in to try to avoid
lip contact that would cause a distortion in
the compound. Figure 4 shows the primary
casts that were constructed from the primary
impressions.
The laboratory subsequently
constructed upper and lower close-fitting
special trays and major impressions were
recorded using greenstick compound
and zinc oxide eugenol. The remainder of
treatment followed the usual stages and the
patient was fitted with dentures.
Given the patient’s post-surgical
stenosis, atrophic maxilla and atrophic
labial sulcus, a Class III incisor relationship
was deemed most appropriate. At try-in,
Figure 1. Extra-oral view of the patient. Figure 2. Maximum mouth opening.

2. January 2018 DentalUpdate 81
TechniqueTips
the upper centre-line matched the midline
of her nasal philtrum. Given the patient’s
asymmetrical face, it was felt to be more
appropriate to adjust the centre-line to
match the LL1−LL2, rather than LL1−LR1, in
order to improve the overall aesthetics of
the dentures. At the next try-in, the patient
expressed high approval with both the fit
and aesthetics of these dentures, so the
fitting proceeded. After the fit stage, the
patient remained very pleased, vocalizing
that the dentures had greatly improved her
aesthetics. The patient was reviewed after
one month and a small part of the lower
denture was eased anteriorly coinciding with
an area of gingival hyperplasia.
The patient was last reviewed
nine months later and reported no problems
apart from a recurrence of BCC (Figure 5).
Overall, she was very satisfied with the
aesthetic and functional result and reported
an improved quality of life. However, she also
reported that her BCC has returned, and she
is awaiting a further course of chemotherapy.
Discussion
This case highlights the
difficulties in managing patients with
microstomia. Microstomia can cause
difficulties during every stage of prosthetic
construction. It was decided to use the bite
fork compound technique; an alternative
technique would have been to use sectional
trays to create a preliminary impression.
However, this technique poses the challenge
involved in relocating the sectional trays
outside the mouth.6
In severe cases of
microstomia, patients can struggle with
the relatively simple tasks of denture
insertion and removal. In this case, the
patient suffered from transient discomfort
when stretching her skin on insertion and
removal of impressions, registration blocks
and the final dentures.
This was a challenging
prosthodontic case, given that the smallest
stock impression tray was too large to
fit intra-orally. It was eventually decided
that the only option, aside from a split
tray technique, was to use the bite fork
innovatively from an articulator with
impression compound to construct a
unique preliminary impression tray which
was suitable for this patient. This worked
well and consideration of this technique is
recommended when a similar situation is
encountered.
After further consideration
of the patient’s unexplained multiple
BCC, perhaps this is a case of Gorlin-Goltz
syndrome.
Conclusion
With the challenges associated
with microstomia, it is important to use
resources already available innovatively to
treat these patients, and ultimately provide
satisfactory dentures. This technique is
both a practical and inexpensive solution,
attractive in modern dentistry as it may
improve both quality of patient care and
cost-effectiveness. We therefore suggest
that, in cases where small stock trays are
too large to fit in patients’mouths, this
compound and bite fork technique is
considered to construct special trays.
Acknowledgements
The authors would like to thank
Mr Andrew Corry, Mr Andrew Fletcher and
Professor David Wilson for their support and
guidance with this case.
Full photo consent for publication
was obtained from the patient.
References
1. Fuller E, Steele J, Watt R, Nuttall N. Oral
Health and Function: A Report from the
Adult Dental Health Survey 2009. The
Health and Social Care Information
Centre, 2011: pp7−8.
2. Garnett MJ, Nohl FS, Barclay SC.
Management of patients with
reduced oral aperture and mandibular
hypomobility (trismus) and implications
for operative dentistry. Br Dent J 2008;
204: 125−131.
3. Kumar KA, Bhat V, Nandini VV, Nair KC.
Preliminary impressions in microstomia
patients: an innovative technique.
J Indian Prosthodont Soc 2013; 13: 52−55.
4. Satpathy A, Guijjari AK. Complete
denture in a microstomia patient.
J Clin Diagn Res 2015; 9: 16−18.
5. Hug AJ, Bogwitz M, Gorelik A, Winship
IM, White SM, Trainer AH. A cohort study
of Gorlin syndrome with emphasis on
standardized phenotyping and quality
of life assessment. Intern Med J 2017;
doi: 10.1111/imj.13429. [Epub ahead of
print].
6. Kumar KA, Bhat V, Nair KC, Suresh R.
Preliminary impression techniques
for microstomia patients. J Indian
Prosthodont Soc 2016; 16: 229−233.
Figure 3. Atrophic lower alveolar ridge and labial
sulcus. Figure 4. Primary casts.
Figure 5. The dentures after nine months, along
with a recurrence of BCC.
Victoria Wilson, BDS, MFDS RCS(Ed), GDP, Select Dental Care, 127 Borough Road, Middlesbrough, TS1 3AN; School of Dental Sciences,
Newcastle University and Janice Ellis, BDS(Hons), FDS RCS(Ed), PhD, ILTM, PGCE, Prosthodontic Consultant, School of Dental Sciences,
Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4BW, UK.