Custom-made 3D printed subperiosteal implant for restoration of
severe atrophic jaw: a case report
In the last decades, considerable progress has been made in the field of
oral implantology, regarding endosseous implants, especially through the
changes brought by the digital revolution. Although their versatility
and predictability has been proven over time through clinical studies
and follow-ups, endosseous implants have certain limitations, mainly
given by the patients’ perspectives: the general state of health, bone
supply, long osseointegration time, etc. Well-designed subperiosteal
implants have been reported to function successfully for many years and
came as an alternative to endoseous implants. The analog method of
inserting subperiosteal implants has been widely discussed and used over
time, and represents a well-defined protocol. However, the first
surgical time, that of taking impression of the residual bone field,
caused problems for the clinicians as follows: the trauma inflicted to
the patient was greater as he was subjected to two surgical
interventions instead of one(first for the impression of the bone and
second for the insertion of the implant), the grip contraction of the
impression material creates the possibility that the implant doesn’t fit
to the bone. Digital technology comes into our hands in order to solve
this unpleasant situations, offering the possibility to design the
future implant on the CBCT scan of the patient long before the surgery
itself.
This case report reviews the design characteristics of 3D printed
superiosteal implants, step by step procedure and its particularities
compared with the analog method, the anatomy of the areas upon which the
implants rest in the maxillae, based on recent research perfomed in
Romania, in collaboration with AB Dental International (1).
Introduction
The use of endosseous dental implants to replace missing teeth has been
a very predictable solution for many years and is now one of the most
common techniques in dental rehabilitation. However, sufficient bone
quantity and quality is required for implantation. In cases of severe
bone resorption, bone regeneration techniques, zygomathic implants,
nerve lateralization and sinus lift surgeries were proposed, but
unfortunatelly these methods require more advanced surgical procedures,
which may result in higher complication rates, morbidity, and longer
treatment times.
Subperiosteal implants were first developed in Sweden at the beginning
of 1940’s and have been used ever since, with a decrease in popularity
with the invention of the first endoseous implants by Branemark.
Subperiosteal implants were custom-made based on an impression obtained
in the stage I surgery and inserted below the periosteum and stabilised
to the bone with mini-screws, then covered by the mucosa in the stage II
surgery. Thus, the pacient was subject to two surgeries at an interval
of 21 days. The subperiosteal implants were made of cobalt-chrome or
titanium alloys and were connected to the prosthesis using transmucosal
abutments that emerged into the oral cavity. Their replacement or
decrease in use was due to the complexity of the production process, the
imperfect fit of the implant caused by relative instability of the
impression material, the wide range of complications (2).
Different protocols have been proposed lately for subperiosteal
implants, especially the ones 3D printed, but infortunately romanian
clinicians need to collaborate with abroad factories or laboratories in
order to treat these cases. Here, the authors present their experience
with an innovative design of a customized subperiosteal implant
manufactured by AB Dental International based on the CBCT scan of the
patient.
Case history/examination
A 58 years old male patient with severe maxillary athrophy was referred
to the clinic due to complaints of inappropriate masticatory and
aesthetic function. He reported a mixed tooth-implant supported
maxillary rehabilitation with five implants and two teeth which failed 3
years ago after more that 15 years of use due to peri-implantitis and
mobility. Ever since, our patient has been wearing a removable acrylic
denture. The pacient denied smoking habits or relevant systemic
diseases. In order to decide whether he is a valid candidate for a
subperiosteal implant or not, the patient was passed through the entire
selection process which included: general examination, clinical local
examination of the oral mouth, laboratory analysis and radiographs. The
pre-operative laboratory analysis were slightly modified with a high
value of the PDW (Platelet Distribution Width) which can indicate anemia
or an infection in the body. Clinical examination [Fig. 1(a)](12)
and orthopatomography [Fig. 1(b)](12) indicated a combined
horizontal and vertical severe osseous atrophy, confirmed through
cone-beam computed tomography (CBCT) [Fig. 2](12).
Note : In some areas, due to the severe bone atrophy, oro-sinusal
communications covered only by the mucosa were evident on the CBCT scan,
in which case the patient’s removable denture functioned as a protective
„shield”.
The cone-beam computed tomography has confirmed an inflamtion of the
sinus mucosa due to odontal causes (infections associated with the
previous teeth) and the severe lack of alveolar bone in all the
maxillary regions that could be seen in the preliminary radiographs. The
highest points of the residual bone were found, firstly, as it can be
observed on the CBCT, in the third molars region both sides [Fig. 2(a)
and 2(b)](12) with dimensions ranging between 2.4 and 7.2 mm in height
and 6.6 and 10.2 mm in width in the first quadran and between 4.8 and
10.2 mm in height and 5.4 and 9.6 mm in width in the second quadran.
Implant placement in the posterior region of the maxilla, the distal
area of the maxillary alveolar process, which corresponds most
frequently to the position of the third molar, has been suggested by
many authors as an alternative to bone grafting. The posterior maxillary
region typically has type III or IV bone quality, consisting of thin
cortical bone and low-density trabecular bone. Primary stability is
adversely affected by this. Due to inadequate primary locking, as well
as short implants having unfavourable biomechanics, this region tends to
have low success rates. Therefore, clinicians face a challenge in
rehabilitating this area (3).
The second area where we could measure some significant alveolar bone is
the second molars region both sides [Fig. 3(a) and 3(b)](12) with
dimensions ranging between 2.1 and 2.7 mm in height and 10.8 mm width in
the first quadran and between 3.0 and 3.9 mm in height and 9.3 and 9.9
mm in width in the second quadran.
As it can be observed in the CBCT scan, in the first molars region both
sides, the residual alveolar bone height is either less that 3.0 mm or
unsignificant [Fig. 3(a), Fig. 4(a)](12), making implant placement
without lateral window sinus lift impossible. In the first quadran, it
is important to notice the abcence of the cortical vestibular bone and
the oral comunication with the maxillary sinus, closed only by the
mucosa (an where we previously mentioned that patient’s removable
denture functioned as a protective “shield”).
As it can be observed in the figures above [Fig 4, Fig. 5 and Fig.
6](12), the other areas of alveolar bone have no significant
dimensions that could be useful for a complete implant-prosthetic
rehabilitation. Thus, the possible initial treatment plan proposed was
bilateral window sinus lifting with delayed implant placement after 8 –
10 months from the initial surgery and guided bone regeneration for
vertical and horizontal deficiency in the frontal area. During these 8
– 10 months of healing, the patient was to be only aesthetically
rehabilitated with a removable prosthesis and the prognosis was
reserved. Because he has high functional and aesthetic requests, and due
to the fact that he has already been edentulous for 3 years by now, we
had to find a more appropriate treatment solution.