Management of a Coronally Advanced Lingual Flap in Regenerative Osseous Surgery: A Case Series Introducing a Novel Technique

Abstract

One of the crucial factors in the success of guided bone regeneration procedures is the correct management of the soft tissues. This allows for stable primary wound closure without tension, which can result in premature exposure of the augmentation area, jeopardizing the final outcome. The use of vertical and periosteal incisions to passivate buccal and lingual flaps in the posterior mandible is often limited by anatomical factors. This paper reports on a series of 69 consecutive cases introducing a novel surgical technique to release and advance the lingual flap coronally in a safe and predictable manner.

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The International Journal of Periodontics & Restorative Dentistry
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Volume 31, Number 5, 2011
505
Management of a Coronally Advanced
Lingual Flap in Regenerative Osseous
Surgery: A Case Series Introducing a
Novel Technique
Marco Ronda, MD, DDS*
Claudio Stacchi, DDS, MSc**
The effectiveness of guided bone
regeneration (GBR) procedures
to promote horizontal and verti-
cal bone regeneration has been
well documented.1–9 Moreover, the
stability of regenerated bone and
its favorable response under func-
tional loading have been demon-
strated.10–13 The ideal goal of this
therapy has shifted from regener-
ating sufcient bone to place im-
plants to reconstructing hard and
soft tissues similar to the prepatho-
logic condition. Vertical GBR is a
technique with great potential, but
it is very demanding for surgical
skills. The careful management of
the soft tissues is key to the success:
Obtaining and maintaining primary
closure of the ap during healing is
necessary to prevent contamination
and infection of the membrane, an
event that always compromises
the augmentation procedure.14,15
Maintaining closure of the ap over
nonresorbable membranes is even
more challenging when compared
to other augmentation procedures
(eg, bone grafting, split crest tech-
niques) because expanded polytet-
rauoroethylene separates the ap
One of the crucial factors in the success of guided bone regeneration
procedures is the correct management of the soft tissues. This allows for
stable primary wound closure without tension, which can result in premature
exposure of the augmentation area, jeopardizing the nal outcome. The
use of vertical and periosteal incisions to passivate buccal and lingual aps
in the posterior mandible is often limited by anatomical factors. This paper
reports on a series of 69 consecutive cases introducing a novel surgical
technique to release and advance the lingual ap coronally in a safe and
predictable manner. (Int J Periodontics Restorative Dent 2011;31:505–513.)
*Private Practice, Genova, Italy.
** Contract Professor, Department of Biomedicine, University of Trieste, Trieste, Italy.
Correspondence to: Dr Marco Ronda, Piazza Brignole 3/8, 16122 Genova, Italy;
fax: +39 010 583435; email: mronda@panet.it.
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The International Journal of Periodontics & Restorative Dentistry
506
from the underlying periosteal vas-
cularization, depriving it of an im-
portant blood supply. Numerous
studies have suggested a variety
of clinical protocols for the man-
agement of soft tissues.16–21 In this
paper, a novel technique for the
coronal displacement of the lingual
ap is described and its clinical ef-
cacy to obtain and maintain pri-
mary closure on the augmentation
area for the entire healing period
evaluated.
Method and materials
Fifty-two patients requiring dental
implants in the posterior mandi-
ble were enrolled in this study. Of
these, 38 (73.1%) were women and
14 (26.9%) were men, with an age
range from 25 to 79 years (mean,
50.9 ± 12.1 years). Twenty patients
were light smokers (38.5%) and
32 were not smokers (61.5%). The
inclusion criteria were mandibu-
lar partial edentulism (Applegate-
Kennedy Class I or II) involving the
premolar/molar area and an as-
sociated presence of crestal bone
height < 7 mm coronal to the man-
dibular canal. General exclusion
criteria were acute myocardial in-
farction within the past 6 months,
uncontrolled coagulation disorders
or metabolic diseases, radiotherapy
to the head or neck region within
the past 24 months, treatment with
intravenous bisphosphonates, psy-
chologic or psychiatric problems,
heavy smoking (> 10 cigarettes/
day), and alcohol or drug abuse.
The local exclusion criterion was the
presence of uncontrolled periodon-
tal disease. All patients signed a
written informed consent form.
At the initial visit, all subjects
underwent clinical examination
with periapical and panoramic ra-
diographs. A prosthetic evalua-
tion with a diagnostic wax-up was
accomplished, and a computed
tomography (CT) scan with a tem-
plate was created to plan implant
surgery. A total of 69 sites in the
posterior mandible were treated by
insertion of dental implants associ-
ated with vertical bone augmenta-
tion procedures.
Surgical protocol
All surgeries and postoperative visits
were conducted by a single opera-
tor. Under local anesthesia (4% ar-
ticaine with epinephrine 1:100,000;
Septanest, Ogna), a full-thickness
crestal incision was performed in
the keratinized tissue from the dis-
tal surface of the more distal tooth
to the retromolar pad, continuing
the incision in the mandibular ra-
mus for 1 cm, and nishing with a
releasing incision on its lateral sur-
face. To preserve the lingual nerve
when approaching the second mo-
lar area, the blade was inclined ap-
proximately 45 degrees with the tip
in a vestibular direction, and the ex-
ternal oblique ridge was used as a
marker for the incision going distally
and buccally, bearing in mind that
the ramus of the mandible ares
up laterally and posteriorly. When
there was a tooth still present pos-
terior to the augmentation area,
the incision continued 5 mm distal
from it before performing the re-
leasing incision.
The ap design was continued
intrasulcularly on both vestibular
and lingual sides of the mesial por-
tion of the ap. Buccally, it involved
two teeth before nishing with a
vertical hockey stick releasing inci-
sion.22 Lingually, it involved one
tooth to the gingival zenith and
then continued horizontally in a
mesial direction for 1 cm in the
kera tinized tissue. A full-thickness
vestibular ap was elevated and,
after isolating the mental nerve, re-
leased with a longitudinal perioste-
al incision avoiding the mental
foramen area. This slight horizontal
cut, performed using a new blade,
was extended from the distal to the
mesial releasing incisions covering
the entire length of the ap. On the
lingual side, a full-thickness muco-
periosteal ap was elevated until
reaching the mylohyoid line. Then,
using a blunt instrument (eg, a
Pritchard elevator), it was localized
a connective tissue band continu-
ing with the epimysium of the my-
lohyoid muscle (Fig 1). This band,
usually located in the rst molar
area, is 1 to 2 cm wide in a mesio-
distal direction and is inserted into
the inner part of the lingual ap ap-
proximately 5 mm from the crest in
an apical direction. The blunt in-
strument was inserted below the
connective band, and, with gentle
traction in the coronal direction,
this muscular insertion was de-
tached from the lingual ap (Figs 2
and 3). The vertical augmentation
procedure was then performed
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Volume 31, Number 5, 2011
507
using a titanium-reinforced ex-
panded polytetrauoroethylene
Gore-Tex membrane (W.L. Gore)
with a composite bone graft. The
grafting material consisted of a 1:1
mixture of mineralized bone al-
lograft (Puros, Zimmer) and autog-
enous bone harvested from the
external oblique ridge with bone
scrapers (Safescraper, Meta).
The implant site prepara-
tions were made using twist drills
and nalized in the last portion
over the mandibular canal with an
OT4 piezoelectric insert (Piezosur-
Fig 1 Cross-sectional anatomical drawing of the rst molar region showing the insertion of the mylohyoid muscle into the lingual ap and
its relations with other anatomical structures of the area.
Fig 2 Detachment of the mylohyoid muscle insertion from the lin-
gual ap was accomplished by applying gentle traction with a blunt
instrument in a coronal direction.
Fig 3 Cross-sectional anatomical drawing of the rst molar region
representing the situation after detachment of the muscular inser-
tion from the lingual ap.
Muscular insertion into the lingual ap
Mylohyoid muscle
Sublingual gland
Wharton duct
Lingual nerve
Hypoglossus nerve
Lingual artery
Submandibular gland
Facial artery
Submandibular lymphnode
Facial vein
Lingual vein
Muscular insertions
after detachment
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The International Journal of Periodontics & Restorative Dentistry
508
gery, Mectron). Implants were then
placed (Spline Twist and Tapered
Screw-Vent, Zimmer) and left to pro-
trude from the original bone level
for the amount of planned vertical
regeneration (Fig 4). After multiple
perforations of the cortical bone,
performed using an OP5 piezo-
electric insert, the composite graft
was positioned and the membrane
was adapted and xed with lingual
and buccal xation tacks (Micropin,
Omnia). The mucoperiosteal aps
were tested for their passivity and
their capability to be displaced to
cover the augmentation area com-
pletely. A double line of suturing
was performed: Horizontal mattress
sutures were used for close contact
between the inner connective por-
tions of the aps, then multiple in-
terrupted sutures (Gore-Tex CV5,
W.L. Gore) followed (Fig 5).
Amoxicillin/clavulanate potas-
sium (875 + 125 mg) and ibuprofen
(600 mg) were prescribed twice a
day for 1 week. Patients were also
instructed to rinse twice a day with
a 0.2% chlorhexidine solution and
to avoid mechanical plaque remov-
al in the surgical area until sutures
were removed. Sutures were re-
moved 10 to 12 days after surgery.
Postsurgical visits were scheduled
at 15-day intervals to check the
course of healing and to verify pri-
mary wound closure in the postop-
erative period. Successful primary
closure was dened as complete
coverage of the membrane for at
least 6 months after the augmen-
tation procedure. Any membrane
exposure was considered a loss of
primary closure and a failure for the
aims of this study.
Statistical analysis
The chi-square test was performed
to analyze nonparametric data
obtained in this study (SPSS 16.0,
IBM).
Fig 4 Implants inserted in place and left to protrude 8 mm from
the original bone level. The membrane is already xed on the lin-
gual side and some cortical perforations are visible.
Fig 5 Primary closure of the aps over the augmentation area with
two lines of sutures.
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Volume 31, Number 5, 2011
509
Results
A total of 69 consecutive vertical
GBR procedures were performed in
this study, with the contextual inser-
tion of 187 implants. The amount
of required vertical regeneration
around implants ranged from 1.1 to
12 mm (mean, 5.2 ± 1.8 mm). The
distribution of the surgical sites by
maximum amount of vertical re-
generation required per site is sum-
marized in Table 1. There were no
dropouts during the entire observa-
tion period. Coronal displacement
of the aps was sufcient to obtain
a complete and passive coverage in
all 69 augmented sites. During the
postoperative period, there were
no recorded hemorrhagic prob-
lems or neurosensory changes. No
evidence of adverse local or sys-
temic side effects was observed in
65 sites throughout the study; in 4
sites, although primary closure of
the aps was perfectly maintained,
there were signs of infection in the
augmented zone (swelling and pu-
rulent exudate) during the rst 2
weeks after surgery. In these cases,
membranes and implants were im-
mediately removed (overall failure
rate, 5.8%). Three of the 4 unsuc-
cessful sites were in smokers (11.1%
failure in the smokers group, 2.4% in
the nonsmokers group). The higher
failure rate in the smokers group re-
sulted in a statistically signicant dif-
ference (P < .001).
No membrane exposure was
observed in any patient during the
entire healing period (Fig 6). Six
months after surgery, the mem-
branes were removed, and im-
plants were connected with healing
abutments (Figs 7 and 8).
Discussion
GBR procedures have evolved
greatly over the last 15 years, al-
lowing for predictable implant
placement in horizontally and ver-
tically augmented ridges.7–13 The
success of this technique is depen-
dent on strict observation of the
surgical protocols. A crucial factor
is to achieve and maintain primary
closure of the aps for the entire
healing period. Flap management
has to fulll two main requirements:
It must allow for complete and pas-
sive coverage of the augmented
zone without any residual tension,
and it must be safe for the adjacent
anatomical structures.
The handling of the soft tissues
has been analyzed in numerous
studies,17–24 but most of them are
focused on the management of the
Table 1 Distribution of surgical sites by amount of vertical
augmentation required
Vertical regeneration No. of sites
< 3 mm 0
3–6 mm 42
6.1–9 mm 24
> 9 mm 3
Total 69
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The International Journal of Periodontics & Restorative Dentistry
510
palatal ap. Coronal displacement
of the lingual ap, essential to GBR
in the posterior mandible, has been
well described7–9,22: After full-
thickness elevation beyond the my-
lohyoid line, a slight mesiodistal in-
cision of the periostium was
performed to advance the ap cor-
onally. This technique is very effec-
tive but, in unexperienced hands,
could be potentially harmful for the
delicate anatomical structures of
the oor of the mouth. The surgical
technique of the coronally ad-
vanced lingual ap presented in
this study is fundamentally based
on the separation of the lingual ap
and the underlying muscular struc-
tures in the molar area. From anato-
my, it is known that the most
posterior portion of the mylohyoid
muscle arises from the lingual tuber-
osity, just below the retromolar pad.
Further, in the molar region, it is lo-
cated very close to the attachment
of the mucous membrane to the
mandible; in the premolar region,
the attachment drops suddenly to a
lower level, giving a distinct step in
the line of origin.25 These anatomi-
cal factors suggest that the close
contact between the mylohyoid
muscle and the lingual ap in the
molar area is an important limitation
in obtaining coronal displacement.
For this reason, the detachment of
the mylohyoid insertion in the molar
zone allows the lingual ap addition-
al extended movement in the coro-
nal direction, enhancing its mobility
greatly (Fig 9). The separation be-
tween the muscle and ap was ob-
tained using a blunt instrument by
applying gentle traction force in a
coronal direction to the connective
tissue, continuing with the epimy-
sium of the mylohyoid muscle with-
out endangering local anatomical
Fig 6 (left) At 6 months, primary closure was perfectly
maintained, and soft tissues appeared healthy.
Fig 7 At removal, the membrane was stable and perfectly adher-
ent to the crest. The regenerated tissue covered the implants, lling
the space delimited by the membrane completely.
Fig 8 Occlusal view of the implants with healing abut-
ments; the height and thickness of the crest were restored
satisfactorily.
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Volume 31, Number 5, 2011
511
Fig 9a Coronal displacement of a lingual ap measured in the mesial
portion after full-thickness elevation until the mylohyoid line (10 mm).
Fig 9b Coronal displacement of the same ap measured in the distal
portion after full-thickness elevation until the mylohyoid line (15 mm)
Fig 9c Detachment of the muscular insertion from the ap obtained
with gentle traction in the coronal direction using a blunt instrument.
Fig 9d Enhancement in coronal displacement of the ap measured
in the mesial portion (19 mm) after detachment of the muscular inser-
tion. Compare to Fig 9a (baseline).
Fig 9e Measurement of coronal advancement obtained in the distal
portion of the ap (29 mm) after detachment of the muscular inser-
tion. Compare to Fig 9b (baseline).
a
c
b
d
e
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The International Journal of Periodontics & Restorative Dentistry
512
structures (eg, lingual nerve, lingual
artery, sublingual gland). Further-
more, with this technique, the lin-
gual ap is elevated only until the
mylohyoid line and not beyond, as
proposed previously,22 providing ad-
ditional protection to the underlying
anatomical structures.
Primary closure of the ap was
maintained in all cases considered
in this study. The four early infec-
tions were likely a result of intra-
operative contamination of the
composite bone graft with bacteria
present in saliva.26 Moreover, the
data seem to conrm, in accor-
dance with the literature,27–29 that
smoking could be a signicant risk
factor that can jeopardize the out-
come of regenerative procedures.
Conclusions
In this case series, the authors in-
troduce a novel technique to cor-
onally advance the lingual ap in
regenerative surgery. In the cases
considered, the proposed surgical
management of the lingual ap re-
sulted in a 100% success rate in the
maintenance of soft tissue primary
closure for a period of 6 months
postoperatively. Moreover, this sur-
gical approach allows for safe dis-
placement of the lingual ap. The
use of blunt instruments and the
elevation limited to the mylohy-
oid line minimize the possibility of
potential damages to the delicate
anatomical structures of the oor of
the mouth.
Acknowledgments
The authors wish to thank Prof Massimo Si-
mion for his precious teaching and sharing
his broad experience and knowledge in the
eld of regenerative techniques. In addition,
grateful thanks are extended to Mrs Laura
Grusovin for her anatomical drawings.
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