endodontics

1. oral surgery
oral medicine
oral pathology
With sections on oral and maxillofacial radiology
and endodontics
oral surgery
Editor:
ROBERT B. SHIRA, DDS
School of Dental Medicine
Tufts University
I Kneeland Street
Boston, Massachusetts 0211I
Recurrence of keratocysts and decompression
treatment
A long-term follow-up of forty-four cases
Niels Br#ndum, DDS, DOS,a and Vagn Juhl Jensen,MD,b Odense,Denmark
Recurrence was found in eight cases (18%) in a group of 44 patients (22 male) with odontogenic
keratocysts treated at the Department of Oral Surgery and Oral Medicine, Odense University Hospital, from
197 1 to 1983. All these recurrences were found in cysts with parakeratotic, thin, bandlike epithelium with
palisade-like basal cells (Forssell group la). In 12 large cysts the use of a polyethylene drainage tube
implanted at cystotomy and biopsy some months before primary cystectomy resulted in considerable
reduction in the cystic lumen and also in alteration of the thin, fragile cystic epithelium into thick, solid
cystic epithelium with no adhesion to the adjoining structures. No recurrence was seen in these 12 patients
after an observation period of between 7 and 17 years. The decompression treatment seems to reduce the
tendency to recurrence of the odontogenic keratocyst, which is far more important than the advantages to
the surgeon of surgical simplicity and safety, and to the patient of less discomfort and pain.
(ORALSURCORALMEDORALPATHOL~~~~;~~:~~~-9)
The recurrence rate of odontogenic keratocysts
(OKCs)’ has been high since the first thorough inves-
tigation of these cysts was reported in 1963.2 Recur-
rence has been described as late as 37 years after pri-
mary cystectomy.3 It has been suggested that recur-
rence is a consequence of technical difficulties in
radical cystectomy, because of the cobweblike cystic
epithelium or because of the localization of the cyst
to inaccessible sites or to adhesions. Attempts have
been made to reduce this high recurrence rate by im-
proved surgical techniques, such as removal of super-
adjacent mucosa, smoothing of the osseouswall of the
cystic cavity, resection of neighboring parts of the
mandible, tanning of the epithelial lining of the cyst
with Carnoy’s solution, cryotherapy, and marsupia-
*Department of Oral Surgery and Oral Medicine.
bDepartment of Oral Pathology.
7/12/31010
lization.4-‘0 A follow-up period of at least 5 years is
advisable because most recurrences develop within
the first 5 years of the initial cystectomy.5y l1
The aim of the present investigation has been to
carry out a long-term follow-up of cases of OKCs
treated at the Department of Oral Surgery and Oral
Medicine, Odense University Hospital, with special
attention given to the relationship between recur-
rence, histologic findings, and surgical technique.
MATERIAL AND METHODS
A total of 51 patients with OKC were treated dur-
ing the period from 1971 to 1983. Two patients with
metaplasia of the OKC developing into ameloblas-
toma were excluded, aswere five with nevoid basal cell
carcinoma syndrome, which carries an increased ten-
dency toward recurrence. i2*13 Thus 44 patients re-
mained: 22 females with a mean age of 47 years
(range 9 to 87 years) and 22 males with a mean age
265

2. 266 Br#ndum and Jensen ORAL SURG ORAL MED ORAL PATHOL
September I99 I
Fig. 1. Endof polyethylenetubeisexpandedby heating
abovespirit lamp.
of 43 years (range 18 to 76 years). The male/female
ratio was thus 1:1.
In 32 cases the diagnosis of OKC was based on a
biopsy taken from material obtained by primary cys-
tectomy. Twelve OKCs were diagnosed at cystotomy
and biopsy of large cysts in connection with insertion
of a polyethylene drainage tube for decompression.
All 44 cysts were classified histopathologically ac-
cording to Forssell groups I to V.14
The Forssell grouping is as follows:
la. Thin, bandlikeparakeratoticcyst epithelium;basal
cellsarecuboidalor columnar,accentuated,andpal-
isade-like
Ib. Epitheliumcomposedmainlyof basalcelllayeronly;
basalcellsaccentuated
II. Orthokeratoticcyst epitheliumwith distinctstratum
granulosum;accentuationof basalcells is not pro-
nounced
III. Cyst epitheliumexhibitingareasof orthokeratiniza-
tion andnonkeratinization
Fig. 2. Collarismoldedbypressingtheheatedtip against
coldglassplate.
Fig. 3. Polyethylenedrainagetubesproducedin various
lengthsandwith varying anglesof collars.
IV. Parakeratoticcyst epitheliumresemblingthe oral
mucousmembrane
V. Cystepitheliumthinandparakeratotic;basalcellsnot
accentuated
Our standard treatment has been primary cystectomy
with smoothing of the osseous wall of the cavity; this
wasemployed in 32 cases.One of these casesrequired
electrocauterization to arrest bleeding from the man-
dibular canal.
A polyethylene drainage tube is inserted in large
follicular or residual cysts as a routine procedure in
connection with cystotomy and biopsy before cystec-
tomy is done. This results in decompression and a
subsequent reduction in the size of the cystic cavity.i5
In 12 cases where biopsy showed OKC, a drainage
tube was inserted 1 to 14 months (mean 10 months)
before primary cystectomy.
The drainage tubes are produced from small lengths
of polyethylene tubing (outer diameter 2.3 mm,
lumen 1.6 mm) by heating the ends in a spirit lamp
(Fig. 1) and then pressing them against a cold glass
plate, thus making a collar at both ends (Fig. 2). Such

3. Keratocyst recurrence and decompression 267Volume 72
Number 3
6 ,’
II
5 I
50 60 70 60
Years
Fig. 4. Distribution of OKCs accordingto ageandsex.
Number
16.
la lb 2 3 4 5
Forssell groups
Fig. 5. Distribution of OKCs according to sex and
Forssellgroup.
Fig. 6. Polyethylenedrainagetubein upperfrontal re-
gion,kept in positionby collars.
tubes can be produced in various lengths and with the
collars at varying angles (Fig. 3). The tube selected
for a particular case should be as short as possible. It
is kept in place by means of the collars. The tube is
introduced through an incision in the mucosal flap
that is elevated to gain access to the cyst for cysto-
tomy and biopsy. After the sutures in the mucosal flap
are removed 5 to 8 days after cystotomy, the patient
is instructed to flush the cavity daily through the tube
with a 0.1% solution of chlorhexidine gluconate until
cystectomy can be carried out; this is done with a
normal syringe and a thin blunt hypodermic needle.
The reduction in the size of the cystic cavity was
assessedby radiologic follow-up every 4 months. The
optimal time for cystectomy and removal of the
drainage tube was determined from the radiologic re-
ductiqn in the cystic lumen.
All patients were seen annually for a clinical and
radiologic follow-up after the first reexamination 9
months after the cystectomy. All data were comput-
erized.
RESULTS
Forssell group Ia comprised 27 patients (14 male);
group Ib was not represented in the material. Forssell
group II included five patients (three male); group III
Fig. 7. Orthopantogram of 21-year-old man showing
OKC in left angularandramusregions.
contained one female, whereas group IV included
three patients (one male); and group V comprised
eight patients (four male). The distribution of OKCs
according to age and sex is shown in Fig. 4; Fig. 5
shows the distribution according to sex and Forssell
group.
Recurrence of OKC occurred in 8 of the 32 patients
treated with primary cystectomy (two men in the age
group 40 to 49 years, and six females, one aged 15
years, two from the age group 40 to 49 years, and
three from the age group 50 to 59 years). Recurrence
occurred only in Forssell group Ia (i.e., the group with
thin parakeratotic cyst epithelium with palisade-like
basal cells).
Of a total of 54 OKCs, 44 (82%) were found in the
mandible, of which 27 were in the ramus and angular
regions (61%) and 17 in the mandibular body (39%).
Ten OKCs (18%) were seen in the upper jaw, of which
seven were in the frontal and canine regions (70%),
and three in the molar region (30%).
All eight recurrences were observed in the mandi-
ble (seven in the angular and ramus regions and one
in the premolar region). Seven of the eight recur-
rences were solitary, and one multiple; three were

4. ORALSURG ORALMEDORAL PATHOL
September1991
Fig. 8. Orthopantogramof samepatient 10monthsafter
insertionof drainagetube, revealingmarkedreductionin
cysticlumen.
Fig. 10. Biopsyin connectionwith cystectomyand re-
movalof tube10monthsafter biopsyin Fig.9,demonstrat-
ing considerablechangein histologicfeatures.Cystcould
not longerbeclassifiedasForssellgroupIa.
Fig. 9. Biopsyin connectionwith cystotomyanddrain-
ageof OKC showninFig.5,displayingOKC Forssellgroup
Ia.
unilobular and five multilobular. Of all 44 cases of
OKC, 37 were solitary and 7 were multiple, and 26
were unilobular and 18 multilobular. The maximum
radiographic diameter was 15 mm in one case (pre-
molar region), 20 to 49 mm in three cases, and more
than 50 mm in four cases. In six of seven casesof re-
currence in the lower third molar region, the ramus
and/or the body of the mandible were involved at pri-
mary cystectomy. Osseous perforation on the lingual
side of the ramus was present in four cases, adhesions
to the content of the mandibular canal in three, and
adhesions to soft tissue in three others. Biopsies taken
from patients with recurrence showed no histologic
alteration in six cases, whereas two casesrecurred as
Forssell group IV and group V, respectively. Recur-
rence was observed in seven patients during the first
2 years of observation and in one patient after 5 years.
Three patients were subjected to reoperation twice;
two of these had involvement of the mandibular canal
and persistent postoperative paresthesia of the lower
lip developed.
A polyethylene drainage tube was inserted after
biopsy, according to the method of Nielsen15 (Fig. 6)
in 12 cases; primary cystectomy was performed on
these patients only after radiographic reduction in the
cystic lumen (Figs. 7 and 8). No recurrence was seen
in these 12 patients during an observation period of
between 7 and 17 years. In the cases shown in Figs.
7 and 8, the cystic epithelium had undergone pro-
nounced histologic change (Figs. 9 and 10). The de-
compression took 1 to 14 months (mean 10 months),
and the largest diameter of the cystic lumen wasmore
than 50 mm in five casesand between 15 and 45 mm
(mean 40 mm) in the remaining seven at the time
when the drainage tube was inserted. Biopsy of the
cystotomy material showed nine cases of Forssell
group Ia, and one in each of groups II, IV, and V.
Forssell group Ia was not found in the cystectomy
material. In four of the nine casesof Forssell group Ia
at cystectomy, the cystectomy material could no
longer be classified as OKC.
Cysts with rapid increase in size showed a corre-
sponding rapid reduction in the cystic lumen after
drainage. However, the actual reduction in the lumi-
nal diameter did not occur as rapidly as that demon-
strated by radiography.
It is noteworthy that the patients had little incon-
venience from the tube, and none had difficulty in the
routine flushing. Therefore cystectomy and removal
of the tube could wait until considerable radiographic
reduction in the size of the cyst had occurred.
Forty-three of the patients were followed for 7 to 19
years (mean 9 years). One patient was followed for
only 22 months before moving from the catchment
area.
DISCUSSION
In the present investigation agreement was good
with other studies with respect to age; most studies

5. Volume 72
Number 3
have shown a marked prevalence of OKC in the age
groups 20 to 29, and 40 to 59 years. There is also
agreement asto the frequent localization of the OKC
to the angular and ramus regions of the mandible.* I, I3
The sex ratio in the current investigation differed
somewhat from that reported in other studies, all
of which have shown a slight male predomi-
nance 4-6,9-l 1, 13
It is remarkable that all the recurrences occurred
in cysts with parakeratotic thin bandlike epithelium
with palisade-like basal cells (Forssell group Ia) and
that all were located in the mandible (seven in the an-
gular and ramus regions and one in the premolar re-
gion). It is also remarkable that the recurrences
occurred three times as often in women as in men (fe-
male/male ratio 6:2).
The frequency of recurrence in 27 OKC cysts with
parakeratotic, thin, bandlike epithelium with pali-
sade-like basal cells was 30% (8/27), whereas the rate
in the whole material was only 18% (8/44).
As in other studies, we found that the recurrence of
OKC is most likely to occur in cases requiring com-
plicated surgery (i.e., in those cases where the OKC
is situated in the angular and ramus regions with in-
volvement of the mandibular canal and/or with
adhesions to soft tissue through osseousperforation).
The change in the histologic features of the cystic
epithelium after the insertion of a drainage tube is
similar to that occurring after inflammation.16
The increased epithelial depth observed after de-
compression facilitated cystectomy, especially when
the latter was performed after a marked reduction in
the cystic lumen. The reduction in the size of the cyst
resulted in achieving a safe distance to the mandibu-
lar canal or other previously involved structures. Thus
postoperative complications were avoided without
difficulty. Finally, the tendency toward recurrence
was reduced or even eliminated entirely, because it
was often possible to remove the cyst in toto.i3
CONCLUSION
The recurrence of OKC is most likely to occur in
parakeratotic OKCs with thin, bandlike epithelium
with palisade-like basal cells (Forssell group Ia). The
use of a polyethylene drain inserted at cystotomy and
biopsy in larger cysts of various types gave a number
of advantages to the surgeon and few inconveniences
to the patient.
1. The diagnosis of OKC (with particular refer-
ence to Forssell group Ia) versus non-OKC can
be established by means of cystotomy or biopsy.
2. The procedure is advantageous for the patient,
because the treatment can be carried out in two
sessions of minor surgery with the patient under
local anesthesia. For the surgeon the method
simplifies the surgical procedure of removing
Keratocyst recurrence and decompression 269
3.
solid coherent cystic tissue with no adhesions
from a minor cavity, instead of removing cob-
weblike, fragile cystic tissue with adhesions to
adjoining structures in a cavity with difficult ac-
cessand entailing the risk of damage to adjoin-
ing structures and the possibility of spontaneous
fracture of the jaw.
Decompression of larger cysts appears to reduce
the tendency to recurrence of OKC.
We thank the staff of the Departmentof Oral Surgery
andOral Medicine,aswelloftheDepartmentofPathology,
OdenseUniversity Hospital,for helpand advice;wealso
thankLiseHansen,MSc, FunenCounty MedicalComput-
ingDepartment,OdenseUniversity Hospital,for thedata
processing.
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Reprint requests:
N. Brdndum, DDS, DOS
Department of Oral Surgery and Oral Medicine
Odense University Hospital
DK-5000 Odense C, Denmark