1. Outcome and quality of life after individual computer-assisted reconstruction
of the midface
1. Outcome and quality of life after individual computer-assisted reconstruction
of the midface
The midface is not only the anatomical center of the face but it is the framework
structure and basic precondition for exercising the identity of an individual. Here,
important senses like vision and smelling are localized as well as functions like
chewing and air passage. It represents a multifunctionality for an anatomical region
with regard to structure and design. If the anatomical integrity of the midface is
impaired due to congenital or acquired deformities, not only the function is
disturbed for the individual but also massively the quality of life [1]. This is an important statement that obliges
to perform particular quality management prior to every surgical intervention in the
area of the midface. In this context, computer assistance may be suitable to make
reconstructive interventions of the midface more predictable, more transparent, and
more verifiable and thus associated with lower risk [2]
[3]. Digital planning
possibilities integrating different surface and volume data including modern
additive production techniques for biomodel and implant manufacturing and
intraoperative support of real and virtual 3D volume data application by means of
navigation as well as intraoperative outcome securing due to 3D volume dataset
assessment with 3D C-arm cone beam tomography have been implemented in modern
midfacial reconstruction and represent new standards for medical care [4]
[5]
[6]
[7]
[8]
[9].
However, an implementation of new technology must always be considered with the
background of clinical significance: the limitations for treatment success are
rarely defined by the technology itself but moreover by clinical reasons like for
example motor impairment, scars, lack of tissue. Thus, the clinician has the immense
responsibility to assess and define the balance of what is theoretically feasible
and what can in fact be achieved. The generation of young surgeons as well as the
more experienced ones have nowadays the unprecedented chance to see and understand
complex reconstructions from the individual three-dimensionality – in all
treatment phases, i. e. the pre-, intra-, and postoperative course [10]. Thus, also the term of quality control has
a completely new dimension and finally allows to create evidence of every individual
case. This means that the term of evidence-based medicine may get a new,
real-surgery, and patient-related perspective [3]
[11].
In the following chapters, the modern options of patient-specific reconstructions
of
the midface including patient-specific implants that have been planned and produced
by means of computer assistance (CAD/CAM) for reconstruction will be
described. In this context, also paradigm shifts will become apparent like for
example the aspect that reconstructions of the orbit must be dimensionally stable
leading to the fact that bioresorbable materials need particular justification [12]
[13]; or
that the unimpaired chewing function of the centrally and/or laterally
ablated midface may be restored by means of a single-time surgery with a primarily
functionally stable, multivector screw retained patient-specific implant [14].
2. Posttraumatic reconstruction of the midface
2. Posttraumatic reconstruction of the midface
In the context of reconstruction of posttraumatic defects, the difference must be
made between primary and secondary reconstruction. Furthermore, there is the
difference between isolated orbital defects and combined orbital and midfacial
defects [8, 10]. Generally, the following
statement is true: Reconstruction is the more difficult the later it is performed
and the more complex the individual trauma pattern is. Quality and methods of
three-dimensional imaging have led to an enormous step forward so that generally no
limitations exist in our healthcare system. In particular spiral CT technology (CT)
and cone beam tomography (CBCT) must be mentioned in the context of midfacial
trauma. Modern CBCT is often superior to CT scan with regard to diagnostics for hard
tissue because metallic artifacts are less negatively overlying compared to CT
diagnostics [14]
[15]. If soft tissue has to be evaluated like for example with regard to
intraorbital bleeding, contrast-enhanced CT scan must certainly be preferred [16]
[17].
The clinically more important problem in traumatology that has to be resolved
imperatively is that 3D datasets should basically have the quality allowing a
digital planning process as integral element [18]. Therefore, traumatology is mentioned as field of indication because
it has the highest requirements with regard to the factor of time in the
chronological treatment course. Hereby, radiologists should know abou what a 3D
dataset may be able to contribute to the treatment beyond diagnostics; and the
surgeons are responsible to explain to the diagnosticians that and which therapeutic
consequences are developed from the 3D datasets. In short, computer-assisted
planning with virtual models and additive manufacturing of 3D biomodels, navigation,
robotics are only possible when the volume data are exported in the DICOM format and
meet the requirements regarding slice thickness and the scanned volume for possible
subsequent applications of technologies. Fortunately, nearly every CT and CBCT
device is nowadays able to perform this. Moreover, the specifications for scanning
with regard to the midface are rather simple, i. e. the alignment of the
object to be scanned in the neutral zero position, axial scan direction, layer
thickness of less than 1 mm. However, in reality these scan and/or
DICOM exportation requirements are not met in about 50% of external dataset
transmission. Thus new 3D volume datasets have to be created – which could
be avoided. In this context, still a lot of information has to be passed on [19].
Based on different areas of indication, modern computer-assisted procedures for
reconstructions of the midface will be presented in the following chapters.
2.1 Primary posttraumatic reconstruction of the midface
2.1 Primary posttraumatic reconstruction of the midface
Due to a fall, an older female patient suffered from right-sided posttraumatic
orbital defect that comprised the sagittal as well as the transversal dimension of
the entire orbital floor. [Fig. 1] shows the
extended defect that involved the transition zone between medial orbital wall and
orbital floor. The justification for the application of patient-specific implants
could be focused over the years on the following indications:
Fig. 1 Posttraumatic defect of the orbital floor on the right side in
coronal sequence a as well as oblique-sagittal sequence b with
subtotal extension of the defect of 25.5 mm seen in CBT.
*transition zone; arrow: posterior ledge.
There is a necessity of dimensionally stable reconstruction in cases of loss of the
so-called key areas of the orbit, those are the anterior 10 mm of the
orbital floor (“postentry zone”, measured from the infraorbital rim
in posterior direction in the paramedian oblique-sagittal plane), the posterior
medial bulge, the region between the posterior wall of the maxillary sinus and the
posterior ledge, the posterior third of the orbital floor, the transition zone
between the medial orbital wall and the orbital floor, or a change of the
lentil-shape-contour of the inferior rectus muscle in the coronal layer to a round
formation as indication for an opening of the periorbita as well as enophthalmos or
hypoglobus. In all mentioned defect constellations of the internal orbit,
patient-specific implants are favored that have the perfect shape and include
elements of functionalization and preventive design. These implants have been
developed by the author’s research group and aim at providing clinically
relevant for intraoperative use as well as allowing the automated alignment of the
STL files of the patient-specific implants in the volume dataset for intraoperative
navigation so that the navigation control may be performed in a pointer-based and
trajectory-based way. This workflow is ensured for IPS Implants® (KLS Martin
Group, Tuttlingen, Germany) in combination with the iPlan® software
(Brainlab, Munich, Germany). In addition, anatomical extensions may be added to
these implants in order to provide further stabilization. A round, circular edging
(thickness of 0.5 mm) allows the atraumatic interaction of the implant with
neighboring tissue of the implant that has only 0.3 mm in its center in the
adequately dissected orbit. In the posterior third of the orbit, a clear curvature
of the implant geometry is found diverging from the area near the optic canal,
shaped like an inverted snow shovel. Multiple slit openings lead to a reduction of
the biomaterial and further for drainage in cases of retrobulbar hematoma. This kind
of implant includes the experience of 30 years of reconstructive orbital surgery and
turned out to avoid the classic mistakes of orbital reconstruction. Fixation at or
behind the infraorbital rim is possible by means of one or two mini-screws measuring
1.2, 1.3, or 1.5 mm in diameter. If needed, fixation may also be performed
at the anterior latero-orbital side ([Fig.
2]).
Fig. 2 Patient-specific implant for reconstruction of the right orbita
(KLS Martin Group, Tuttlingen, Germany) with several functionalizations.
Arrows: trajectories for intraoperative navigation; ǂpreventive
design with caudally angulated dorsal support (inverted snow shovel);
*reconstruction of the posterior medial bulge.
Approaches for orbital reconstruction may generally be smaller, however, they have
to
meet the requirements of sufficient dissection. The authors have acquired excellent
results mainly with the inferior transconjunctival retroseptal approach for the
reconstruction of the orbital floor and the caudal parts of the lateral and medial
orbital wall ([Fig 3]) – in
exceptional cases, canthotomy may be performed for a better overview. If the median
orbital wall has to be reconstructed until the inferior part of the anterior skull
base, additionally the median transconjunctival approach is recommended from trans-
or retrocaruncular direction. Superior parts of the lateral orbital wall and the
lateral area of the orbital roof may be safely treated via the superior lateral
blepharoplasty approach. Eyebrow incision should no longer be applied.
Fig. 3 Clinical pictures of an inferior, transconjunctival,
retroseptal approach. Incision at least 10 mm dorsally to the eyelid
a; exposition of the orbital floor b with fracture zone
(arrows). Intraoperative imaging by means of CBCT after insertion of the
implant in coronal c and diagonal-sagittal paramedian d
sequence.
2.2 Secondary posttraumatic reconstruction of the orbit and the midface
2.2 Secondary posttraumatic reconstruction of the orbit and the midface
Secondary reconstructions have the advantage of a longer time for planning and
preparation. The orbit and the midface are the most challenging regions for
secondary reconstructions because the interaction only of the orbit is associated
with 50% of the 12 cranial nerves. The complexity is defined by the
anatomical and functional deficit and becomes even more difficult because of often
high expectations in the sense of restitutio ad integrum which in cases of
secondary corrections is nearly impossible. Only the best possible improvement of
the condition can be aimed at that has to be balanced between realistic outcomes and
the patient’s expectations.
After primary treatment of severe injury with midfacial and orbital fractures several
months ago, [Fig. 4] shows the radiological
analogue findings of the clinically apparent deformity of the female patient. In the
context of primary treatment, reposition of the midfacial structures had been
performed with insertion of bioresorbable material and also the reconstruction of
the internal orbita, however, all these structures are now in the fixed stage of
apparent malposition and thus inadequately treated. Clinically, a hypoglobus with
massive enophthalmos on the right imposes as well as massive retrusion of the right
prominence of the right side. Together with the patient the decision was made to
correct the outer frame for adequate reconstruction of the midface and the orbit in
the same session. This included the recontouring of the right orbit. With the
clinical information and the assessment of the tissue situation, the planning
requirements are transmitted to the industrial partner so that preoperatively ideal
patient-specific implants can be digitally planned and manufactured computer
assistance. Exemplarily, some screenshots from the planning view are displayed that
show the implant for the external frame as well as the planned functionalized
multi-wall implant for the right orbit with aforementioned preventive design [Fig. 4]. Both implants define separately and in
combination the correct position of the malar bone that has to be corrected. The
infrared-based navigation was performed intraoperatively for control of the drilling
direction and anchoring in the area of the lateral skull base. Pointer-based
navigation and trajectory-based navigation were applied in order to verify the
correct dissection as well as the implant position in relation to the neighboring
structures.
Fig. 4 Planning of a secondary correction of the malar bone with
segmentation of the bone healed in malposition a, which is
repositioned b, as well as a patient-specific implant (PSI) for
definition of the ideal position d and another PSI for orbital
reconstruction based on the now volume-enhanced new situation e.
Preoperative CBCT c with malposition of the malar bone and
postoperative f after correction.
The surgical access was performed for the orbit via the transconjunctival retroseptal
approach, for the lateral frame the transoral and pre-auricular approach on the
right side was chosen.
The major need of the patient, namely the correction of the facial deformity
including the malposition of the globe with diplopia was met. The orbital volume
enlargement was additionally corrected by means of titanium spacers ([Fig. 5]). Furthermore, ENT surgeons performed
opening and stenting of the right nasofrontal duct.
Fig. 5 CBCT of the patient from [fig.
4] before orbital reconstruction a+c with an extended
orbital defect and after reconstruction b+d by means of
patient-specific orbital implant as well as titanium spacers for volume
augmentation.
This case report reveals the enormous contribution to quality management due to
computer-assistance at three different stages of treatment: preoperative,
intraoperative, and postoperative.
3. Growth-related acquired deformity of the orbit and the midface
3. Growth-related acquired deformity of the orbit and the midface
Due to an inflammatory disease of the right maxillary sinus with surgical treatment
in early childhood, the adult patient showed the clinical picture of a complex
facial asymmetry induced by growth disorder of the midface with retrusion of the
right malar bone, an orbital asymmetry with hypoglobus and right-sided enophthalmos
as well as an occlusal cant ([Fig. 6]).
Radiologically, the bony walls of the maxillary sinus were thickened. Primarily, the
assessment and association of the asymmetry to the anatomical structures had to be
performed. The transition zone between the medial wall and the right orbital floor
was shifted in caudal direction, the orbital volume was enlarged on the right side
in comparison to the non-affected contralateral side.
Fig. 6 Preoperative CBCT of a female patient with midfacial deformity
in axial a and coronal plane b with hypoplastic right
maxillary sinus (star) as well as reactive increase of density of the
surrounding bone (arrow) and clearly backshifted prominence of right malar
bone.
The result of the interactive imaging analysis between surface and volume data and
the correlation to the clinically assessable asymmetry led to the following
treatment plan. In two sessions, first the lateral midface and the right orbit
should be reconstructed and symmetrized. In a second intervention, bimaxillary
orthognatic surgery was planned in order to correct the central midface and the
mandible. While the midfacial deformity caused the patient’s major
suffering, the jaws were not the leading problem so that corrective osteotomy was
finally not performed. However, in order not to spoil this option for the future,
the orbital and midfacial reconstruction had to be planned in that way that later
Le
Fort I osteotomy was possible without jeopardizing the outcome of the first
intervention.
For the orbit and also for the external midfacial skeleton, two independent
patient-specific implants were planned that could be inserted independently from
each other in case of complications. Furthermore, a two-part PEEK
(polyetheretherketon) implant for the near-nerve augmentation in the area of the
malar bone was chosen in order to surgically realize the contour and volume effect
around the area near the infraorbital nerve with low risk and to achieve less heat
conduction of the material. For correction of the globe position, however, an IPS
implant® (KLS Martin Group, Tuttlingen, Germany) was manufactured for the
orbit in a laser melting process that was fixed independently from the PEEK implant
([Fig. 7]). Both implant types could be
inserted in the planned target position only via the transoral approach and the
retroseptal transconjunctial approach. Postoperatively, diplopia was observed for
some weeks that disappeared in the visual field as well as in direct vision.
Fig. 7 Planning a of a reconstruction for the patient from
[fig. 6] by means of
patient-specific orbital implant as well as two-part PEEK implant.
Intraoperative situation b with preservation of the infraorbital
nerve (arrow).
4. Defects of the maxilla and midface
4. Defects of the maxilla and midface
Dental implantology is one of the major achievements of modern maxillofacial and
dental surgery that is mainly based on the implantation of an alloplastic foreign
body into the existing bone. If the conditions are unfavorable regarding bone
situation and quality combined with negatively enhancing biomechanical stress with
regard to an increased atrophy, all conventional procedures of pre-implantological
bone transplantation with subsequent application of conventional dental implants are
limited. This situation becomes worse when additional general diseases and
medication as well as irradiation or impaired immune system, tissue defects and
replacement complicate the basic condition.
Conventional therapy strategies also include the classic external sinus lift by means
of an osteoplasty in the alveolar recess, which already may lead to a complex
disease and that usually heals without complication if autogenous bone is used in
cases of maxillary sinusitis. The widespread application of so-called bone
replacement materials of self-proclaimed implantologists in often uncontrolled ways
may lead to serious inflammations and thus additional loss of bone and tissue.
The problem of unfavorable biomechanical stress in cases of severe atrophy in form
of
a Angle class III relation is one of the biggest challenges for the weak and
atrophic maxilla and was the origin of a new treatment strategy where
computer-assisted planning with innovations in biomedical technology achieved a new
approach in form of the patient-specific implants (individual patient-specific
solution [IPS] implants® Preprosthetic, KLS Martin Group, Tuttlingen,
Germany). Furthermore, it is a preventive treatment response because conventional
procedures were often characterized by an enormous invasiveness or represented a
biologically inadequate approach for already incurable or hardly treatable patients
because they were too old, too sick, or already pre-injured. In this context,
“preventive” means that this procedure that has been newly developed
by the authors leaves out for example the maxillary sinus and internal midfacial
structures and merely rests on the remaining bone-structures in combination with a
rigidly multivector screw retention. This procedure is not competitive to dental
implantology but it may be a crucial line-extension for those cases where the
invasiveness of classic pre-implantological interventions is considered as
inadequate. Apart from this, the conventional strategies are associated with a
treatment protocol that takes about one year. So all conventional strategies have
to
be considered critically and even more at risk with regard to the target, the more
unfavorable the above-mentioned skeletal relationship is in direction of an Angle
class III. Here, only the zygomatic-implant must be mentioned as possible
alternative for the atrophic maxilla, however, it has basic design weaknesses
because the anchoring is off-site in the zygoma – which is generally
positive – but the implant axis is in direct neighborhood or even in the
passage through the maxillary sinus. If anterior teeth remain in the mandible, the
treatment of the extremely atrophic maxilla requires particularly stable conditions.
This consideration is not at all limited to old patients but already e. g.,
in young patients suffering from syndromic diseases associated with teeth loss or
also compromise-afflicted singularly conservative orthodontic compensation attempts
in cases of e. g., patients with severe cleft palate and limited maxillary
growth, complex biomechanically lip and induced teeth and subsequent bone loss may
be observed early. In these cases, at least the intact mandibular situation must be
considered as causal for a decompensation mechanism due to an unequal or overload
of
the anterior maxillary region that may lead to extremely atrophic maxillae already
in middle-aged patients. A particular challenge is the combination of maxillary
weakness due to severe atrophy with additional ablation of maxillary parts and
surrounding soft tissue as a consequence of radical surgery after malignant
diseases, sometimes combined with adjuvant radio- and/or chemotherapy with
at the same time fully dentated mandible. Regarding the planning process for
computer-assisted production of an IPS implant® Preprosthetic, there is
generally no difference to the otherwise typical planning of dental implant
treatment. This means that the planning may be performed in an analogue, digital,
or
even combined analogue/digital way. Mainly in cases of non-defined maxillary
relation and occlusal height, a radiopaque wax setup should be performed and be an
integral part of the pretherapeutic scan volume either in CBCT or CT scan. If
preoperative situations are present as 3D datasets based on plaster models, these
data may be integrated in the planning dataset. The number of pillars and their
alignment have to be defined in order to design their digital connection to the
basic framework.
[Fig. 8] shows the clinical condition of a
84-year-old female patient after multiple surgical interventions with scarring and
tissue reaction on the uncontrolled insertion of inadequate quantities of bone
substitutes in the massively atrophic maxilla as well as the maxillary sinus on both
sides. Diagnostic CBCT allowed the analysis of the bone and displayed the massively
dislocated radiodense bone substitute in both maxillary sinuses so that first this
material had to be comprehensively removed.
Fig. 8 Patient with insufficient intraoral situation for prosthesis
placement after augmentation elsewhere with bone substitutes. Intraoral
situation a and CBT b with depiction of the bone replacement
material (arrows).
Preexisting oroantral fistulas in the bilateral dental areas healed consequently.
The
patient did not want new attempts of pre-implantological augmentations. Also, for
the mandible, the disturbing concept of the previous treatment became obvious in
form of very rigid anchoring of the dental prosthesis with completely malpositioned
dental implant axes with regard to the already weakened maxilla, i. e., by
lifting the implant shoulders in labial direction, the biomechanical stress was
additionally negatively enhanced for the extremely atrophic maxilla ([Fig. 9]).
Fig. 9 CBCT in sagittal layer of the patient from [fig. 8] with unfavorable Angle class
III relation (arrow) as well as peri-implant bone loss (*).
The decision was made for the treatment alternative by means of an
IPS-Implants® Preprosthetic for the extremely atrophic maxilla that was
maximally disadvantaged due to the foreign material. [Fig. 10] shows the situation after removal of
the infected bone substitute with ventilated maxillary sinuses as well as a splint
for backwards planning worn in the context of 3D scan.
Fig. 10 CBCT in coronal layer of the patient from [figs. 8] and [9] after removal of the bone
replacement material a as well as orthopantomography b after
insertion of a patient-specific framework implant (IPS-Implants®
Preprosthetic, KLS Martin Group, Tuttlingen, Germany). Clinical situation
after healing with telescopes c and definitive dentures in situ
d.
Treatment was performed in one single session by means of an IPS-Implants®
Preprosthetic which is possible as an outpatient procedure due to the less invasive
approach. In contrast to conventional augmentative procedures, this implant can be
loaded immediately which is a great advantage in particular for older patients who
shun complex multistage treatment concepts.
4.1 Cleft lip and palate related midfacial defects
4.1 Cleft lip and palate related midfacial defects
[Fig. 11] shows a large anterior oronasal
fistula after loss of the premaxilla in the context of primary intervention
performed elsewhere. In [Fig. 11b], the
computer-assisted planning for reconstruction by means of an IPS-Implants®
Preprosthetic shows the new unfavorable skeletal Angle class III relation. In the
interactive viewer of the case designer, different planning stages are displayed
from different views by including soft tissue information based on the scanned
edentulous maxilla model, the scanned prosthetic wax setup for the planned maxillary
denture, the planned occlusion level, and the framework implant with necessary bone
resection. The design of the IPS-Implants® Preprosthetic allows an important
protrusion of the pillars in order to compensate the position of the clearly
backwards located maxilla compared to the skeletal mandible. The surgery itself is
performed on an outpatient basis and allows the rehabilitation of complex maxillary
defects within one day which would be impossible for conventional protocols that
take at least one year – with associated severe morbidity.
Fig. 11 Patient with extended residual cleft a and
prosthetically unfavorable Angle class III relation b. Digital
backwards planning of prosthetic rehabilitation c including the soft
tissue situation d with patient-specific framework implant
e+f (IPS-Implants® Preprosthetic, KLS Martin Group,
Tuttlingen, Germany).
According to the case presentation in [Fig.
11], the functionalized and preventive design for the IPS-Implants®
Preprosthetic must be particularly mentioned which means that a clear positioning
is
given that may be supported by additional three-dimensional landmarks that may be
designed for the individual implant like small stabilizers, arms, or flunges around
anatomical structures. In the maxilla, mainly the middle and lateral midfacial
pillars around the piriform aperture or the alveolar zygomatic crest are used. The
thickness of the framework basis can be designed in a tapered way to the palpable
edge, the use of 1.5 or 2.0 mm non-locking or also locking osteosynthesis
screws is possible. The basic principle is the primarily stable osteosynthesis
performed remote from the pillar passages.
For better protection of the buccal soft tissue against the framework implant posts,
sheathing of the pillar passages in the posterior area by means of the buccal fat
pad shifted in anterior direction turned out to be beneficial for the atrophic
maxilla. Furthermore, in cases of a very irregular alveolar ridge, the limited
removal of crestal parts of the alveolar ridge may be justified so that an improved
congruence between the bottom of the implant and the receiver region may be achieved
([Fig. 12a]). This resection may be
planned digitally in advance and transferred into an individual 3D resection
template that is then used immediately prior to insertion of the
IPS-Implants® Preprosthetic for modification of the alveolar ridge. Of
course, the IPS-Implants® Preprosthetic may be combined with conventional
dental implants. The provisional prosthetic treatment for the IPS-Implants®
Preprosthetic is performed with application of a simple metal bar that serves as
quality management tool for checking the parallelism of the single pillars of the
IPS-Implants® Preprosthetics at the time of surgical intervention. In the
further course it may be used together with a matrix for anchoring a bar-supported
temporary prosthesis.
Fig. 12 Intraoperative situation of the patient from [fig. 11] with patient-specific template
a as well as coverage of the framework implant c with
buccal fat pad b. Postoperative situation after insertion of the
implant in OPT d and clinically e as well as after
implementation of the dentures f.
Despite simultaneous or delayed restoration with e. g. soft and hard tissue
transplantation, the maxillary tissue loss is generally a challenge for the
treatment strategy of dental rehabilitation, which can only be considered as being
successful when finally also a biologically adequate dental rehabilitation can be
achieved. Outstanding microsurgical reconstruction that do neither functionally nor
anatomically achieve the sufficient separation of the biological units and also the
restoration of a bony basis that cannot bear any implant, are biologically
inadequate and have to be rated as reconstruction failure since they are measured
with the above-mentioned parameters. Regarding treatment in our healthcare system
that allows implant-supported dental rehabilitation for tumor-related maxilla
ablation, always bone reconstruction in cases of partially, hemi- or completely
maxillectomized patients has to be performed based on prosthetic backwards planning
in order to find a planning approach for a later successful implant-supported
prosthetic rehabilitation. However, there is an enormous gap between clinical
reality and quality management that is required for these reconstructive
interventions.
4.2 Postablative maxillary and midfacial defects
[Fig. 13] shows the clinical situation of a
multilocular melanoma of the maxilla. According to the recommendations of the
interdisciplinary tumor board, immune therapy and irradiation of the patient were
performed in addition to radical resection (maxillectomy). After pathohistological
confirmation of the R0 resection stage and exclusively for separation of anatomical
units and for preservation of the perioral, oral, and oropharyngeal competence, the
intraoral microsurgical soft tissue reconstruction by means of a microvascular
anastomosed latissimus dorsi flap ([Fig. 13c])
was performed as delayed primary reconstruction. [Fig. 13d] illustrates the postablatively found class III relation with
adequately present mandibular dentition. Without massive bone transplantation, an
implant-supported prosthetic treatment would not have been possible. However, for
the patient this meant possible donor site morbidities at the bone graft harvesting
sites (iliac crest, scapula, or fibula) as well as an overall rehabilitation time
of
about one year beside an inpatient treatment including intensive care.
Fig. 13 Patient with multilocular melanoma of the maxilla a+b
as well as after maxillectomy and reconstruction by means of a microvascular
anastomosed latissimus dorsi flap c. Delayed primary reconstruction
by means of a digitally planned d patient-specific framework implant
e and definitive treatment with coverdenture f.
Instead, an IPS-Implants® Preprosthetic was early inserted secondarily in the
context of an outpatient intervention with first provisional prosthetic treatment
and full primary functional stability and thus unlimited biomechanical stress
possibilities. In particular the intraoperative view ([Fig. 13e]) reveals the complex anchoring in the
bony central and lateral midface as well as the one-piece implant with widely
protruded posts. [Fig. 13f] shows the clinical
site with the definitive prosthetic treatment supported by the transorally inserted
implant with a removable bar-supported palate-free coverdenture.
Fig. 14 Computed tomography a of a patient after midfacial
ablation and adjuvant therapy because of an adenoidcystic carcinoma.
Secondary reconstruction by means of a patient-specific framework implant
(IPS-Implants Preprosthetic, KLS Martin Group, Tuttlingen, Germany). Digital
planning b with anchoring in the area of the left-sided zygomatic
arch. The arrow shows optional screw holes for anchoring in the lateral
midface. Patient-specific implant c on a stereolithography model.
Intraoral situation after implant insertion and microvascular anastomosed
tissue transfer d with telescope-supported prosthesis e.
In case of later secondary treatment of maxilla and midface for oncologic patients,
the therapy sequelae of tissue loss, xerostomia, irradiation, scarring have to be
considered even more critically. This matter is illustrated in a patient who
underwent curative irradiation after ablation without performing primary restoration
of the ablated midface and maxilla. Temporarily, the patient was treated with a
multi-piece obturator for the missing central midfacial structures. The left
maxillary dentition was found in the osteonecrotic bone of the centrolateral
maxillary alveolar process and the bony midface. The two-stage reconstruction
concept consisted of separating anatomical units, the extraoral soft tissue and the
intraoral soft tissue, while especially the lip competence should be preserved and
the oral and oropharyngeal competence should be restored. However, due to the
complete soft palate loss, restitutio ad integrum was not completely possible
for the velopharyngeal area.
The necrotic bone was removed from the left midface and it was covered by means of
a
microvascular latissimus dorsi flap that wasanastomosed on the left side cervically,
the central maxillary and midfacial defects were obliterated. By means of an
ipsilateral preauricularly anastomosed microvascular radial forearm flap, the
pre-reconstructed horizontal unit – with separation of the oral from the
nasal cavity and the paranasal sinuses – was separated from the vertical
unit consisting of upper lip and cheek. Between the separation borders created in
this way, the later pillar passages of the IPS-Implants® Preprosthetic were
planned. After healing of at least three months, the one-piece framework implant
could be inserted in a functionally stable way and provisionally equipped with
dentures. The definitive prosthetic treatment was performed on telescopes with
modular coverdenture.
The difficulty of an implant-supported dental rehabilitation of the maxilla is not
only defined by the remaining maxillary bone or the bone quality but moreover by the
clinically based assessment of the integrity and adequate separation of anatomical
units of the bony maxilla including the surrounding and neighboring soft tissue
structures in relation to the individual functional and anatomical mandibular
circumstances. Only the overall assessment represents the basis for qualified
therapy decisions of the individual patient. It is generally true that the more a
mandible goes in direction of an Angle class III with regard to biomechanics and
skeleton, the more biomechanically stable the overall concept has to be for the
affected maxilla and the neighboring midface. In this context, the advantage of
primarily functionally stable patient-specific framework implants is seen for the
dental rehabilitation of patients with extreme maxillary atrophy or conditions after
maxillary ablation because these frameworks – despite higher efforts for the
treating physicians – represent the most modern and rapid form of
mechanically immediately usable dental rehabilitation for the patient. Even tumor
patients consider them as highly positive with regard to their quality of life.
Conclusion
Modern possibilities of interactive imaging analysis based
on standardized volume datasets optimally created for diagnostics and exported in
DICOM format, have the high potential to support all reconstructive measures in the
midface, independently from the indication, in all treatment stages [20]. It is the task of the treating disciplines
to know about these treatment options in order to use them for the benefit of the
individual patient, depending on the indication. In this way, significant
improvements of the quality of life may be achieved for indications in the areas of
oncology, traumatology, acquired or congenital malformations, and severe atrophies
[21].
